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Meyer, Joel

Overview:

Dr. Meyer studies the effects of toxic agents and stressors on human and wildlife health. He is particularly interested in understanding the mechanisms by which environmental agents cause DNA damage, the molecular processes that organisms employ to protect prevent and repair DNA damage, and genetic differences that may lead to increased or decreased sensitivity to DNA damage. Mitochondrial DNA damage and repair, as well as mitochondrial function in general, are a particular focus. He studies these effects in the nematode Caenorhabditis elegans, in cell culture, and collaboratively in other laboratory model organisms as well as in human populations in the USA and globally.

Positions:

Associate Professor of Environmental Genomics in the Division of Environmental Sciences and Policy

Environmental Sciences and Policy
Nicholas School of the Environment

Associate Professor in the Department of Civil and Environmental Engineering

Civil and Environmental Engineering
Pratt School of Engineering

Faculty Network Member of The Energy Initiative

Duke University Energy Initiative
Institutes and Provost's Academic Units

Affiliate, Duke Global Health Institute

Duke Global Health Institute
Institutes and Provost's Academic Units

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

B.S. 1992

B.S. — Juniata College

Ph.D. 2003

Ph.D. — Duke University

News:

Grants:

GW150184 Mitochondrial dysfunction and Gulf War Illness

Administered By
Environmental Sciences and Policy
AwardedBy
United States Army Medical Research Acquisition Activity
Role
Principal Investigator
Start Date
September 15, 2016
End Date
September 14, 2019

Role of Mitochondrial CYP2E1 in Chemical Exposure-Driven Neurodegeneration

Administered By
Environmental Sciences and Policy
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
August 01, 2016
End Date
July 31, 2019

Are mitochondria a major target of antimicrobial silver nanoparticles?

Administered By
Environmental Sciences and Policy
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
March 01, 2017
End Date
February 28, 2019

Cooperative Program in Nanomaterials Hazard and Exposure Assessment Traineeships (NanoHEAT)

Administered By
Pratt School of Engineering
AwardedBy
Environmental Protection Agency
Role
Mentor
Start Date
December 01, 2015
End Date
November 30, 2018

Center for Environmental Implications of Nanotechnology

Administered By
Pratt School of Engineering
AwardedBy
National Science Foundation
Role
Investigator
Start Date
October 01, 2008
End Date
August 31, 2018

Duke University Program in Environmental Health

Administered By
Environmental Sciences and Policy
AwardedBy
National Institute of Environmental Health Sciences
Role
Mentor
Start Date
July 01, 2013
End Date
June 30, 2018

Genetic sensitivity to mitochondrial toxicity

Administered By
Environmental Sciences and Policy
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
May 01, 2016
End Date
April 30, 2018

REU Site: Research Experiences for Undergraduates in Environmental Implications of Nanotechnology

Administered By
Pratt School of Engineering
AwardedBy
National Science Foundation
Role
Mentor
Start Date
May 01, 2014
End Date
April 30, 2018

The Role of Mitochondrial DNA Damage in Neurodegeneration

Administered By
Environmental Sciences and Policy
AwardedBy
National Institutes of Health
Role
Principal Investigator
Start Date
August 16, 2011
End Date
April 30, 2017

Fluoride and human health: Assessing novel biomarkers in detecting bone disorder

Administered By
Earth and Ocean Sciences
AwardedBy
National Institutes of Health
Role
Collaborator
Start Date
April 20, 2015
End Date
March 31, 2017

REU Site: Research Experience for Undergraudates on Environmental Implications of Nanotechnology at Duke, Carnegie Mello

Administered By
Pratt School of Engineering
AwardedBy
National Science Foundation
Role
Mentor
Start Date
July 15, 2010
End Date
October 31, 2014

COPAS BIOSORT Worm Sorter

Administered By
Neurology, Headache and Pain
AwardedBy
National Institutes of Health
Role
Collaborator
Start Date
December 01, 2009
End Date
December 09, 2010
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Publications:

Effects of methyl and inorganic mercury exposure on genome homeostasis and mitochondrial function in Caenorhabditis elegans.

Mercury toxicity mechanisms have the potential to induce DNA damage and disrupt cellular processes, like mitochondrial function. Proper mitochondrial function is important for cellular bioenergetics and immune signaling and function. Reported impacts of mercury on the nuclear genome (nDNA) are conflicting and inconclusive, and mitochondrial DNA (mtDNA) impacts are relatively unknown. In this study, we assessed genotoxic (mtDNA and nDNA), metabolic, and innate immune impacts of inorganic and organic mercury exposure in Caenorhabditis elegans. Genotoxic outcomes measured included DNA damage, DNA damage repair (nucleotide excision repair, NER; base excision repair, BER), and genomic copy number following MeHg and HgCl2 exposure alone and in combination with known DNA damage-inducing agents ultraviolet C radiation (UVC) and hydrogen peroxide (H2O2), which cause bulky DNA lesions and oxidative DNA damage, respectively. Following exposure to both MeHg and HgCl2, low-level DNA damage (∼0.25 lesions/10kb mtDNA and nDNA) was observed. Unexpectedly, a higher MeHg concentration reduced damage in both genomes compared to controls. However, this observation was likely the result of developmental delay. In co-exposure treatments, both mercury compounds increased initial DNA damage (mtDNA and nDNA) in combination with H2O2 exposure, but had no impact in combination with UVC exposure. Mercury exposure both increased and decreased DNA damage removal via BER. DNA repair after H2O2 exposure in mercury-exposed nematodes resulted in damage levels lower than measured in controls. Impacts to NER were not detected. mtDNA copy number was significantly decreased in the MeHg-UVC and MeHg-H2O2 co-exposure treatments. Mercury exposure had metabolic impacts (steady-state ATP levels) that differed between the compounds; HgCl2 exposure decreased these levels, while MeHg slightly increased levels or had no impact. Both mercury species reduced mRNA levels for immune signaling-related genes, but had mild or no effects on survival on pathogenic bacteria. Overall, mercury exposure disrupted mitochondrial endpoints in a mercury-compound dependent fashion.

Authors
Wyatt, LH; Luz, AL; Cao, X; Maurer, LL; Blawas, AM; Aballay, A; Pan, WKY; Meyer, JN
MLA Citation
Wyatt, LH, Luz, AL, Cao, X, Maurer, LL, Blawas, AM, Aballay, A, Pan, WKY, and Meyer, JN. "Effects of methyl and inorganic mercury exposure on genome homeostasis and mitochondrial function in Caenorhabditis elegans." DNA repair (February 13, 2017).
PMID
28242054
Source
epmc
Published In
DNA Repair
Publish Date
2017
DOI
10.1016/j.dnarep.2017.02.005

Biogas Stoves Reduce Firewood Use, Household Air Pollution, and Hospital Visits in Odisha, India.

Traditional cooking using biomass is associated with ill health, local environmental degradation, and regional climate change. Clean stoves (liquefied petroleum gas (LPG), biogas, and electric) are heralded as a solution, but few studies have demonstrated their environmental health benefits in field settings. We analyzed the impact of mainly biogas (as well as electric and LPG) stove use on social, environmental, and health outcomes in two districts in Odisha, India, where the Indian government has promoted household biogas. We established a cross-sectional observational cohort of 105 households that use either traditional mud stoves or improved cookstoves (ICS). Our multidisciplinary team conducted surveys, environmental air sampling, fuel weighing, and health measurements. We examined associations between traditional or improved stove use and primary outcomes, stratifying households by proximity to major industrial plants. ICS use was associated with 91% reduced use of firewood (p < 0.01), substantial time savings for primary cooks, a 72% reduction in PM2.5, a 78% reduction in PAH levels, and significant reductions in water-soluble organic carbon and nitrogen (p < 0.01) in household air samples. ICS use was associated with reduced time in the hospital with acute respiratory infection and reduced diastolic blood pressure but not with other health measurements. We find many significant gains from promoting rural biogas stoves in a context in which traditional stove use persists, although pollution levels in ICS households still remained above WHO guidelines.

Authors
Lewis, JJ; Hollingsworth, JW; Chartier, RT; Cooper, EM; Foster, WM; Gomes, GL; Kussin, PS; MacInnis, JJ; Padhi, BK; Panigrahi, P; Rodes, CE; Ryde, IT; Singha, AK; Stapleton, HM; Thornburg, J; Young, CJ; Meyer, JN; Pattanayak, SK
MLA Citation
Lewis, JJ, Hollingsworth, JW, Chartier, RT, Cooper, EM, Foster, WM, Gomes, GL, Kussin, PS, MacInnis, JJ, Padhi, BK, Panigrahi, P, Rodes, CE, Ryde, IT, Singha, AK, Stapleton, HM, Thornburg, J, Young, CJ, Meyer, JN, and Pattanayak, SK. "Biogas Stoves Reduce Firewood Use, Household Air Pollution, and Hospital Visits in Odisha, India." Environmental science & technology 51.1 (January 2017): 560-569.
PMID
27785914
Source
epmc
Published In
Environmental Science & Technology
Volume
51
Issue
1
Publish Date
2017
Start Page
560
End Page
569
DOI
10.1021/acs.est.6b02466

Arsenite Uncouples Mitochondrial Respiration and Induces a Warburg-Like Effect in Caenorhabditis elegans.

Authors
Luz, AT; Godebo, TR; Bhatt, DP; Ilkayeva, OR; Maurer, LL; Hirschey, MD; Meyer, JN
MLA Citation
Luz, AT, Godebo, TR, Bhatt, DP, Ilkayeva, OR, Maurer, LL, Hirschey, MD, and Meyer, JN. "Arsenite Uncouples Mitochondrial Respiration and Induces a Warburg-Like Effect in Caenorhabditis elegans." Toxicological sciences : an official journal of the Society of Toxicology 154.1 (November 2016): 195-.
PMID
27794142
Source
epmc
Published In
Toxicological Sciences (Elsevier)
Volume
154
Issue
1
Publish Date
2016
Start Page
195
DOI
10.1093/toxsci/kfw185

Distinctive adaptive response to repeated exposure to hydrogen peroxide associated with upregulation of DNA repair genes and cell cycle arrest.

Many environmental and physiological stresses are chronic. Thus, cells are constantly exposed to diverse types of genotoxic insults that challenge genome stability, including those that induce oxidative DNA damage. However, most in vitro studies that model cellular response to oxidative stressors employ short exposures and/or acute stress models. In this study, we tested the hypothesis that chronic and repeated exposure to a micromolar concentration of hydrogen peroxide (H2O2) could activate DNA damage responses, resulting in cellular adaptations. For this purpose, we developed an in vitro model in which we incubated mouse myoblast cells with a steady concentration of ~50μM H2O2 for one hour daily for seven days, followed by a final challenge of a 10 or 20X higher dose of H2O2 (0.5 or 1mM). We report that intermittent long-term exposure to this oxidative stimulus nearly eliminated cell toxicity and significantly decreased genotoxicity (in particular, a >5-fold decreased in double-strand breaks) resulting from subsequent acute exposure to oxidative stress. This protection was associated with cell cycle arrest in G2/M and induction of expression of nine DNA repair genes. Together, this evidence supports an adaptive response to chronic, low-level oxidative stress that results in genomic protection and up-regulated maintenance of cellular homeostasis.

Authors
Santa-Gonzalez, GA; Gomez-Molina, A; Arcos-Burgos, M; Meyer, JN; Camargo, M
MLA Citation
Santa-Gonzalez, GA, Gomez-Molina, A, Arcos-Burgos, M, Meyer, JN, and Camargo, M. "Distinctive adaptive response to repeated exposure to hydrogen peroxide associated with upregulation of DNA repair genes and cell cycle arrest." Redox biology 9 (October 2016): 124-133.
PMID
27479053
Source
epmc
Published In
Redox Biology
Volume
9
Publish Date
2016
Start Page
124
End Page
133
DOI
10.1016/j.redox.2016.07.004

Intracellular trafficking pathways in silver nanoparticle uptake and toxicity in Caenorhabditis elegans.

We used the nematode Caenorhabditis elegans to study the roles of endocytosis and lysosomal function in uptake and subsequent toxicity of silver nanoparticles (AgNP) in vivo. To focus on AgNP uptake and effects rather than silver ion (AgNO3) effects, we used a minimally dissolvable AgNP, citrate-coated AgNPs (CIT-AgNPs). We found that the clathrin-mediated endocytosis inhibitor chlorpromazine reduced the toxicity of CIT-AgNPs but not AgNO3. We also tested the sensitivity of three endocytosis-deficient mutants (rme-1, rme-6 and rme-8) and two lysosomal function deficient mutants (cup-5 and glo-1) as compared to wild-type (N2 strain). One of the endocytosis-deficient mutants (rme-6) took up less silver and was resistant to the acute toxicity of CIT-AgNPs compared to N2s. None of those mutants showed altered sensitivity to AgNO3. Lysosome and lysosome-related organelle mutants were more sensitive to the growth-inhibiting effects of both CIT-AgNPs and AgNO3. Our study provides mechanistic evidence suggesting that early endosome formation is necessary for AgNP-induced toxicity in vivo, as rme-6 mutants were less sensitive to the toxic effects of AgNPs than C. elegans with mutations involved in later steps in the endocytic process.

Authors
Maurer, LL; Yang, X; Schindler, AJ; Taggart, RK; Jiang, C; Hsu-Kim, H; Sherwood, DR; Meyer, JN
MLA Citation
Maurer, LL, Yang, X, Schindler, AJ, Taggart, RK, Jiang, C, Hsu-Kim, H, Sherwood, DR, and Meyer, JN. "Intracellular trafficking pathways in silver nanoparticle uptake and toxicity in Caenorhabditis elegans." Nanotoxicology 10.7 (September 2016): 831-835.
PMID
26559224
Source
epmc
Published In
Nanotoxicology (Informa)
Volume
10
Issue
7
Publish Date
2016
Start Page
831
End Page
835
DOI
10.3109/17435390.2015.1110759

Effects of reduced mitochondrial DNA content on secondary mitochondrial toxicant exposure in Caenorhabditis elegans.

The mitochondrial genome (mtDNA) is intimately linked to cellular and organismal health, as demonstrated by the fact that mutations in and depletion of mtDNA result in severe mitochondrial disease in humans. However, cells contain hundreds to thousands of copies of mtDNA, which provides genetic redundancy, and creates a threshold effect in which a large percentage of mtDNA must be lost prior to clinical pathogenesis. As certain pharmaceuticals and genetic mutations can result in depletion of mtDNA, and as many environmental toxicants target mitochondria, it is important to understand whether reduced mtDNA will sensitize an individual to toxicant exposure. Here, using ethidium bromide (EtBr), which preferentially inhibits mtDNA replication, we reduced mtDNA 35-55% in the in vivo model organism Caenorhabditis elegans. Chronic, lifelong, low-dose EtBr exposure did not disrupt nematode development or lifespan, and induced only mild alterations in mitochondrial respiration, while having no effect on steady-state ATP levels. Next, we exposed nematodes with reduced mtDNA to the known and suspected mitochondrial toxicants aflatoxin B1, arsenite, paraquat, rotenone or ultraviolet C radiation (UVC). EtBr pre-exposure resulted in mild sensitization of nematodes to UVC and arsenite, had no effect on AfB1 and paraquat, and provided some protection from rotenone toxicity. These mixed results provide a first line of evidence suggesting that reduced mtDNA content may sensitize an individual to certain environmental exposures.

Authors
Luz, AL; Meyer, JN
MLA Citation
Luz, AL, and Meyer, JN. "Effects of reduced mitochondrial DNA content on secondary mitochondrial toxicant exposure in Caenorhabditis elegans." Mitochondrion 30 (September 2016): 255-264.
PMID
27566481
Source
epmc
Published In
Mitochondrion
Volume
30
Publish Date
2016
Start Page
255
End Page
264
DOI
10.1016/j.mito.2016.08.014

From the Cover: Arsenite Uncouples Mitochondrial Respiration and Induces a Warburg-like Effect in Caenorhabditis elegans.

Millions of people worldwide are chronically exposed to arsenic through contaminated drinking water. Despite decades of research studying the carcinogenic potential of arsenic, the mechanisms by which arsenic causes cancer and other diseases remain poorly understood. Mitochondria appear to be an important target of arsenic toxicity. The trivalent arsenical, arsenite, can induce mitochondrial reactive oxygen species production, inhibit enzymes involved in energy metabolism, and induce aerobic glycolysis in vitro, suggesting that metabolic dysfunction may be important in arsenic-induced disease. Here, using the model organism Caenorhabditis elegans and a novel metabolic inhibition assay, we report an in vivo induction of aerobic glycolysis following arsenite exposure. Furthermore, arsenite exposure induced severe mitochondrial dysfunction, including altered pyruvate metabolism; reduced steady-state ATP levels, ATP-linked respiration and spare respiratory capacity; and increased proton leak. We also found evidence that induction of autophagy is an important protective response to arsenite exposure. Because these results demonstrate that mitochondria are an important in vivo target of arsenite toxicity, we hypothesized that deficiencies in mitochondrial electron transport chain genes, which cause mitochondrial disease in humans, would sensitize nematodes to arsenite. In agreement with this, nematodes deficient in electron transport chain complexes I, II, and III, but not ATP synthase, were sensitive to arsenite exposure, thus identifying a novel class of gene-environment interactions that warrant further investigation in the human populace.

Authors
Luz, AL; Godebo, TR; Bhatt, DP; Ilkayeva, OR; Maurer, LL; Hirschey, MD; Meyer, JN
MLA Citation
Luz, AL, Godebo, TR, Bhatt, DP, Ilkayeva, OR, Maurer, LL, Hirschey, MD, and Meyer, JN. "From the Cover: Arsenite Uncouples Mitochondrial Respiration and Induces a Warburg-like Effect in Caenorhabditis elegans." Toxicological sciences : an official journal of the Society of Toxicology 152.2 (August 2016): 349-362.
Website
http://hdl.handle.net/10161/12419
PMID
27208080
Source
epmc
Published In
Toxicological Sciences (Elsevier)
Volume
152
Issue
2
Publish Date
2016
Start Page
349
End Page
362
DOI
10.1093/toxsci/kfw093

In Vivo Determination of Mitochondrial Function Using Luciferase-Expressing Caenorhabditis elegans: Contribution of Oxidative Phosphorylation, Glycolysis, and Fatty Acid Oxidation to Toxicant-Induced Dysfunction.

Mitochondria are a target of many drugs and environmental toxicants; however, how toxicant-induced mitochondrial dysfunction contributes to the progression of human disease remains poorly understood. To address this issue, in vivo assays capable of rapidly assessing mitochondrial function need to be developed. Here, using the model organism Caenorhabditis elegans, we describe how to rapidly assess the in vivo role of the electron transport chain, glycolysis, or fatty acid oxidation in energy metabolism following toxicant exposure, using a luciferase-expressing ATP reporter strain. Alterations in mitochondrial function subsequent to toxicant exposure are detected by depleting steady-state ATP levels with inhibitors of the mitochondrial electron transport chain, glycolysis, or fatty acid oxidation. Differential changes in ATP following short-term inhibitor exposure indicate toxicant-induced alterations at the site of inhibition. Because a microplate reader is the only major piece of equipment required, this is a highly accessible method for studying toxicant-induced mitochondrial dysfunction in vivo. © 2016 by John Wiley & Sons, Inc.

Authors
Luz, AL; Lagido, C; Hirschey, MD; Meyer, JN
MLA Citation
Luz, AL, Lagido, C, Hirschey, MD, and Meyer, JN. "In Vivo Determination of Mitochondrial Function Using Luciferase-Expressing Caenorhabditis elegans: Contribution of Oxidative Phosphorylation, Glycolysis, and Fatty Acid Oxidation to Toxicant-Induced Dysfunction." Current protocols in toxicology 69 (August 2016): 25.8.1-25.8.22.
PMID
27479364
Source
epmc
Published In
Current Protocols in Toxicology
Volume
69
Publish Date
2016
Start Page
25.8.1
End Page
25.8.22
DOI
10.1002/cptx.10

Antagonistic Growth Effects of Mercury and Selenium in Caenorhabditis elegans Are Chemical-Species-Dependent and Do Not Depend on Internal Hg/Se Ratios.

The relationship between mercury (Hg) and selenium (Se) toxicity is complex, with coexposure reported to reduce, increase, and have no effect on toxicity. Different interactions may be related to chemical compound, but this has not been systematically examined. Our goal was to assess the interactive effects between the two elements on growth in the nematode Caenorhabditis elegans, focusing on inorganic and organic Hg (HgCl2 and MeHgCl) and Se (selenomethionine, sodium selenite, and sodium selenate) compounds. We utilized aqueous Hg/Se dosing molar ratios that were either above, below, or equal to 1 and measured the internal nematode total Hg and Se concentrations for the highest concentrations of each Se compound. Observed interactions were complicated, differed between Se and Hg compounds, and included greater-than-additive, additive, and less-than-additive growth impacts. Biologically significant interactions were only observed when the dosing Se solution concentration was 100-25,000 times greater than the dosing Hg concentration. Mitigation of growth impacts was not predictable on the basis of internal Hg/Se molar ratio; improved growth was observed at some internal Hg/Se molar ratios both above and below 1. These findings suggest that future assessments of the Hg and Se relationship should incorporate chemical compound into the evaluation.

Authors
Wyatt, LH; Diringer, SE; Rogers, LA; Hsu-Kim, H; Pan, WK; Meyer, JN
MLA Citation
Wyatt, LH, Diringer, SE, Rogers, LA, Hsu-Kim, H, Pan, WK, and Meyer, JN. "Antagonistic Growth Effects of Mercury and Selenium in Caenorhabditis elegans Are Chemical-Species-Dependent and Do Not Depend on Internal Hg/Se Ratios." Environmental science & technology 50.6 (March 3, 2016): 3256-3264.
Website
http://hdl.handle.net/10161/12421
PMID
26938845
Source
epmc
Published In
Environmental Science & Technology
Volume
50
Issue
6
Publish Date
2016
Start Page
3256
End Page
3264
DOI
10.1021/acs.est.5b06044

PCR-Based Analysis of Mitochondrial DNA Copy Number, Mitochondrial DNA Damage, and Nuclear DNA Damage.

Because of the role that DNA damage and depletion play in human disease, it is important to develop and improve tools to assess these endpoints. This unit describes PCR-based methods to measure nuclear and mitochondrial DNA damage and copy number. Long amplicon quantitative polymerase chain reaction (LA-QPCR) is used to detect DNA damage by measuring the number of polymerase-inhibiting lesions present based on the amount of PCR amplification; real-time PCR (RT-PCR) is used to calculate genome content. In this unit, we provide step-by-step instructions to perform these assays in Homo sapiens, Mus musculus, Rattus norvegicus, Caenorhabditis elegans, Drosophila melanogaster, Danio rerio, Oryzias latipes, Fundulus grandis, and Fundulus heteroclitus, and discuss the advantages and disadvantages of these assays.

Authors
Gonzalez-Hunt, CP; Rooney, JP; Ryde, IT; Anbalagan, C; Joglekar, R; Meyer, JN
MLA Citation
Gonzalez-Hunt, CP, Rooney, JP, Ryde, IT, Anbalagan, C, Joglekar, R, and Meyer, JN. "PCR-Based Analysis of Mitochondrial DNA Copy Number, Mitochondrial DNA Damage, and Nuclear DNA Damage." Current protocols in toxicology 67 (February 2016): 20.11.1-20.11.25.
Website
http://hdl.handle.net/10161/12422
PMID
26828332
Source
epmc
Published In
Current Protocols in Toxicology
Volume
67
Publish Date
2016
Start Page
20.11.1
End Page
20.11.25
DOI
10.1002/0471140856.tx2011s67

Mitochondrial DNA damage induced autophagy, cell death, and disease.

Mammalian mitochondria contain multiple small genomes. While these organelles have efficient base excision removal of oxidative DNA lesions and alkylation damage, many DNA repair systems that work on nuclear DNA damage are not active in mitochondria. What is the fate of DNA damage in the mitochondria that cannot be repaired or that overwhelms the repair system? Some forms of mitochondrial DNA damage can apparently trigger mitochondrial DNA destruction, either via direct degradation or through specific forms of autophagy, such as mitophagy. However, accumulation of certain types of mitochondrial damage, in the absence of DNA ligase III (Lig3) or exonuclease G (EXOG), can directly trigger cell death. This review examines the cellular effects of persistent damage to mitochondrial genomes and discusses the very different cell fates that occur in response to different kinds of damage.

Authors
Van Houten, B; Hunter, SE; Meyer, JN
MLA Citation
Van Houten, B, Hunter, SE, and Meyer, JN. "Mitochondrial DNA damage induced autophagy, cell death, and disease." Frontiers in bioscience (Landmark edition) 21 (January 2016): 42-54. (Review)
Website
http://hdl.handle.net/10161/12423
PMID
26709760
Source
epmc
Published In
Frontiers in bioscience : a journal and virtual library
Volume
21
Publish Date
2016
Start Page
42
End Page
54
DOI
10.2741/4375

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition).

Authors
Klionsky, DJ; Abdelmohsen, K; Abe, A; Abedin, MJ; Abeliovich, H; Acevedo Arozena, A; Adachi, H; Adams, CM; Adams, PD; Adeli, K; Adhihetty, PJ; Adler, SG; Agam, G; Agarwal, R; Aghi, MK; Agnello, M; Agostinis, P; Aguilar, PV; Aguirre-Ghiso, J; Airoldi, EM; Ait-Si-Ali, S; Akematsu, T; Akporiaye, ET; Al-Rubeai, M; Albaiceta, GM; Albanese, C; Albani, D; Albert, ML; Aldudo, J; Algül, H; Alirezaei, M; Alloza, I; Almasan, A; Almonte-Beceril, M; Alnemri, ES; Alonso, C; Altan-Bonnet, N; Altieri, DC et al.
MLA Citation
Klionsky, DJ, Abdelmohsen, K, Abe, A, Abedin, MJ, Abeliovich, H, Acevedo Arozena, A, Adachi, H, Adams, CM, Adams, PD, Adeli, K, Adhihetty, PJ, Adler, SG, Agam, G, Agarwal, R, Aghi, MK, Agnello, M, Agostinis, P, Aguilar, PV, Aguirre-Ghiso, J, Airoldi, EM, Ait-Si-Ali, S, Akematsu, T, Akporiaye, ET, Al-Rubeai, M, Albaiceta, GM, Albanese, C, Albani, D, Albert, ML, Aldudo, J, Algül, H, Alirezaei, M, Alloza, I, Almasan, A, Almonte-Beceril, M, Alnemri, ES, Alonso, C, Altan-Bonnet, N, and Altieri, DC et al. "Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)." Autophagy 12.1 (January 2016): 1-222.
PMID
26799652
Source
epmc
Published In
Autophagy
Volume
12
Issue
1
Publish Date
2016
Start Page
1
End Page
222
DOI
10.1080/15548627.2015.1100356

A systematic review of evidence for silver nanoparticle-induced mitochondrial toxicity

Authors
Maurer, LL; Meyer, JN
MLA Citation
Maurer, LL, and Meyer, JN. "A systematic review of evidence for silver nanoparticle-induced mitochondrial toxicity." Environ. Sci.: Nano 3.2 (2016): 311-322.
Website
http://hdl.handle.net/10161/12420
Source
crossref
Published In
Environmental Science: Nano
Volume
3
Issue
2
Publish Date
2016
Start Page
311
End Page
322
DOI
10.1039/C5EN00187K

Caenorhabditis elegans as a Model for Toxic Effects of Nanoparticles: Lethality, Growth, and Reproduction.

The nematode Caenorhabditis elegans is extensively utilized in toxicity studies. C. elegans offers a high degree of homology with higher organisms, and its ease of use and relatively inexpensive maintenance have made it an attractive complement to mammalian and ecotoxicological models. C. elegans provides multiple benefits, including the opportunity to perform relatively high-throughput assays on whole organisms, a wide range of genetic tools permitting investigation of mechanisms and genetic sensitivity, and transparent bodies that facilitate toxicokinetic studies. This unit describes protocols for three nanotoxicity assays in C. elegans: lethality, growth, and reproduction. This unit focuses on how to use these well-established assays with nanoparticles, which are being produced in ever-increasing volume and exhibit physicochemical properties that require alteration of standard toxicity assays. These assays permit a broad phenotypic assessment of nanotoxicity in C. elegans, and, when used in combination with genetic tools and other assays, also permit mechanistic insight.

Authors
Maurer, LL; Ryde, IT; Yang, X; Meyer, JN
MLA Citation
Maurer, LL, Ryde, IT, Yang, X, and Meyer, JN. "Caenorhabditis elegans as a Model for Toxic Effects of Nanoparticles: Lethality, Growth, and Reproduction." Current protocols in toxicology 66 (November 2, 2015): 20.10.1-20.1025.
PMID
26523472
Source
epmc
Published In
Current Protocols in Toxicology
Volume
66
Publish Date
2015
Start Page
20.10.1
End Page
20.1025
DOI
10.1002/0471140856.tx2010s66

Seahorse Xfe 24 Extracellular Flux Analyzer-Based Analysis of Cellular Respiration in Caenorhabditis elegans.

Mitochondria are critical for their role in ATP production as well as multiple nonenergetic functions, and mitochondrial dysfunction is causal in myriad human diseases. Less well appreciated is the fact that mitochondria integrate environmental and intercellular as well as intracellular signals to modulate function. Because mitochondria function in an organismal milieu, there is need for assays capable of rapidly assessing mitochondrial health in vivo. Here, using the Seahorse XF(e) 24 Extracellular Flux Analyzer and the pharmacological inhibitors dicyclohexylcarbodiimide (DCCD, ATP synthase inhibitor), carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP, mitochondrial uncoupler), and sodium azide (cytochrome c oxidase inhibitor), we describe how to obtain in vivo measurements of the fundamental parameters [basal oxygen consumption rate (OCR), ATP-linked respiration, maximal OCR, spare respiratory capacity, and proton leak] of the mitochondrial respiratory chain in the model organism Caenorhabditis elegans.

Authors
Luz, AL; Smith, LL; Rooney, JP; Meyer, JN
MLA Citation
Luz, AL, Smith, LL, Rooney, JP, and Meyer, JN. "Seahorse Xfe 24 Extracellular Flux Analyzer-Based Analysis of Cellular Respiration in Caenorhabditis elegans." Current protocols in toxicology 66 (November 2, 2015): 25.7.1-25.715.
PMID
26523474
Source
epmc
Published In
Current Protocols in Toxicology
Volume
66
Publish Date
2015
Start Page
25.7.1
End Page
25.715
DOI
10.1002/0471140856.tx2507s66

Reducing Environmental Toxicity of Silver Nanoparticles through Shape Control.

The use of antibacterial silver nanomaterials in consumer products ranging from textiles to toys has given rise to concerns over their environmental toxicity. These materials, primarily nanoparticles, have been shown to be toxic to a wide range of organisms; thus methods and materials that reduce their environmental toxicity while retaining their useful antibacterial properties can potentially solve this problem. Here we demonstrate that silver nanocubes display a lower toxicity toward the model plant species Lolium multiflorum while showing similar toxicity toward other environmentally relevant and model organisms (Danio rerio and Caenorhabditis elegans) and bacterial species (Esherichia coli, Bacillus cereus, and Pseudomonas aeruginosa) compared to quasi-spherical silver nanoparticles and silver nanowires. More specifically, in the L. multiflorum experiments, the roots of silver nanocube treated plants were 5.3% shorter than the control, while silver nanoparticle treated plant roots were 39.6% shorter than the control. The findings here could assist in the future development of new antibacterial products that cause less environmental toxicity after their intended use.

Authors
Gorka, DE; Osterberg, JS; Gwin, CA; Colman, BP; Meyer, JN; Bernhardt, ES; Gunsch, CK; DiGulio, RT; Liu, J
MLA Citation
Gorka, DE, Osterberg, JS, Gwin, CA, Colman, BP, Meyer, JN, Bernhardt, ES, Gunsch, CK, DiGulio, RT, and Liu, J. "Reducing Environmental Toxicity of Silver Nanoparticles through Shape Control." Environmental science & technology 49.16 (August 2015): 10093-10098.
PMID
26146787
Source
epmc
Published In
Environmental Science & Technology
Volume
49
Issue
16
Publish Date
2015
Start Page
10093
End Page
10098
DOI
10.1021/acs.est.5b01711

Metabolic reprogramming and dysregulated metabolism: cause, consequence and/or enabler of environmental carcinogenesis?

Environmental contributions to cancer development are widely accepted, but only a fraction of all pertinent exposures have probably been identified. Traditional toxicological approaches to the problem have largely focused on the effects of individual agents at singular endpoints. As such, they have incompletely addressed both the pro-carcinogenic contributions of environmentally relevant low-dose chemical mixtures and the fact that exposures can influence multiple cancer-associated endpoints over varying timescales. Of these endpoints, dysregulated metabolism is one of the most common and recognizable features of cancer, but its specific roles in exposure-associated cancer development remain poorly understood. Most studies have focused on discrete aspects of cancer metabolism and have incompletely considered both its dynamic integrated nature and the complex controlling influences of substrate availability, external trophic signals and environmental conditions. Emerging high throughput approaches to environmental risk assessment also do not directly address the metabolic causes or consequences of changes in gene expression. As such, there is a compelling need to establish common or complementary frameworks for further exploration that experimentally and conceptually consider the gestalt of cancer metabolism and its causal relationships to both carcinogenesis and the development of other cancer hallmarks. A literature review to identify environmentally relevant exposures unambiguously linked to both cancer development and dysregulated metabolism suggests major gaps in our understanding of exposure-associated carcinogenesis and metabolic reprogramming. Although limited evidence exists to support primary causal roles for metabolism in carcinogenesis, the universality of altered cancer metabolism underscores its fundamental biological importance, and multiple pleiomorphic, even dichotomous, roles for metabolism in promoting, antagonizing or otherwise enabling the development and selection of cancer are suggested.

Authors
Robey, RB; Weisz, J; Kuemmerle, NB; Salzberg, AC; Berg, A; Brown, DG; Kubik, L; Palorini, R; Al-Mulla, F; Al-Temaimi, R; Colacci, A; Mondello, C; Raju, J; Woodrick, J; Scovassi, AI; Singh, N; Vaccari, M; Roy, R; Forte, S; Memeo, L; Salem, HK; Amedei, A; Hamid, RA; Williams, GP; Lowe, L; Meyer, J; Martin, FL; Bisson, WH; Chiaradonna, F; Ryan, EP
MLA Citation
Robey, RB, Weisz, J, Kuemmerle, NB, Salzberg, AC, Berg, A, Brown, DG, Kubik, L, Palorini, R, Al-Mulla, F, Al-Temaimi, R, Colacci, A, Mondello, C, Raju, J, Woodrick, J, Scovassi, AI, Singh, N, Vaccari, M, Roy, R, Forte, S, Memeo, L, Salem, HK, Amedei, A, Hamid, RA, Williams, GP, Lowe, L, Meyer, J, Martin, FL, Bisson, WH, Chiaradonna, F, and Ryan, EP. "Metabolic reprogramming and dysregulated metabolism: cause, consequence and/or enabler of environmental carcinogenesis?." Carcinogenesis 36 Suppl 1 (June 2015): S203-S231. (Review)
PMID
26106140
Source
epmc
Published In
Carcinogenesis
Volume
36 Suppl 1
Publish Date
2015
Start Page
S203
End Page
S231
DOI
10.1093/carcin/bgv037

AHR2-Mediated transcriptomic responses underlying the synergistic cardiac developmental toxicity of PAHs.

Polycyclic aromatic hydrocarbons (PAHs) induce developmental defects including cardiac deformities in fish. The aryl hydrocarbon receptor (AHR) mediates the toxicity of some PAHs. Exposure to a simple PAH mixture during embryo development consisting of an AHR agonist (benzo(a)pyrene-BaP) with fluoranthene (FL), an inhibitor of cytochrome p450 1(CYP1)--a gene induced by AHR activation--results in cardiac deformities. Exposure to BaP or FL alone at similar concentrations alters heart rates, but does not induce morphological deformities. Furthermore, AHR2 knockdown prevents the toxicity of BaP + FL mixture. Here, we used a zebrafish microarray analysis to identify heart-specific transcriptomic changes during early development that might underlie cardiotoxicity of BaP + FL. We used AHR2 morphant embryos to determine the role of this receptor in mediating toxicity. Control and knockdown embryos at 36 h post-fertilization were exposed to DMSO, 100 μg/l BaP, 500 μg/l FL, or 100 μg/l BaP + 500 μg/l FL, and heart tissues for RNA were extracted at 2, 6, 12, and 18 h-post-exposure (hpe), prior to the appearance of cardiac deformities. Data show AHR2-dependent BaP + FL effects on expression of genes involved in protein biosynthesis and neuronal development in addition to signaling molecules and their associated molecular pathways. Ca(2+)-cycling and muscle contraction genes were the most significantly differentially expressed category of transcripts when comparing BaP + FL-treated AHR2 morphant and control embryos. These differences were most prominent at 2 and 6 hpe. Therefore, we postulate that BaP + FL may affect cellular Ca(2+) levels and subsequently cardiac muscle function, potentially underlying BaP + FL cardiotoxicity.

Authors
Jayasundara, N; Van Tiem Garner, L; Meyer, JN; Erwin, KN; Di Giulio, RT
MLA Citation
Jayasundara, N, Van Tiem Garner, L, Meyer, JN, Erwin, KN, and Di Giulio, RT. "AHR2-Mediated transcriptomic responses underlying the synergistic cardiac developmental toxicity of PAHs." Toxicological sciences : an official journal of the Society of Toxicology 143.2 (February 2015): 469-481.
PMID
25412620
Source
epmc
Published In
Toxicological Sciences (Elsevier)
Volume
143
Issue
2
Publish Date
2015
Start Page
469
End Page
481
DOI
10.1093/toxsci/kfu245

Silver nanoparticle toxicity to Atlantic killifish (Fundulus heteroclitus) and Caenorhabditis elegans: a comparison of mesocosm, microcosm, and conventional laboratory studies.

The use of silver nanoparticles (AgNPs) in consumer products and industrial applications, as well as their recent detection in waste streams, has created concern about potential impacts on aquatic ecosystems. The effect of complex environmental media on AgNP toxicity was investigated using wetland mesocosms and smaller scale microcosms. Mesocosms were dosed with 2.5 mg Ag/L as gum arabic (GA)-coated AgNPs, polyvinylpyrrolidone (PVP)-coated AgNPs, or AgNO3. Water samples were taken from mesocosms 24 h after dosing for acute toxicity tests with embryos and larvae of Atlantic killifish (Fundulus heteroclitus) and the nematode Caenorhabditis elegans. Acute toxicity tests were also performed on Atlantic killifish with AgNO3, GA AgNPs, and PVP AgNPs prepared in the laboratory with similar water. For killifish embryos, mesocosm samples were much less toxic than laboratory samples for all types of silver. For larvae, in contrast, all 3 silver mesocosm treatments exhibited toxicity. Interestingly, mesocosm samples of AgNO3 were less toxic than laboratory samples; samples containing GA AgNPs were similar in toxicity, and samples containing PVP AgNPs were more toxic. For C. elegans, results were similar to killifish larvae. Results obtained from the mesocosms were not replicated on the smaller scale of the microcosms. These results indicate that environmental factors unique to the mesocosms acted differentially on AgNO3 to reduce its toxicity in a manner that does not translate to AgNPs for larval fish.

Authors
Bone, AJ; Matson, CW; Colman, BP; Yang, X; Meyer, JN; Di Giulio, RT
MLA Citation
Bone, AJ, Matson, CW, Colman, BP, Yang, X, Meyer, JN, and Di Giulio, RT. "Silver nanoparticle toxicity to Atlantic killifish (Fundulus heteroclitus) and Caenorhabditis elegans: a comparison of mesocosm, microcosm, and conventional laboratory studies." Environmental toxicology and chemistry 34.2 (February 2015): 275-282.
PMID
25393776
Source
epmc
Published In
Environmental Toxicology & Chemistry
Volume
34
Issue
2
Publish Date
2015
Start Page
275
End Page
282
DOI
10.1002/etc.2806

PCR based determination of mitochondrial DNA copy number in multiple species.

Mitochondrial DNA (mtDNA) copy number is a critical component of overall mitochondrial health. In this chapter, we describe methods for isolation of both mtDNA and nuclear DNA (nucDNA) and measurement of their respective copy numbers using quantitative PCR. Methods differ depending on the species and cell type of the starting material and availability of specific PCR reagents.

Authors
Rooney, JP; Ryde, IT; Sanders, LH; Howlett, EH; Colton, MD; Germ, KE; Mayer, GD; Greenamyre, JT; Meyer, JN
MLA Citation
Rooney, JP, Ryde, IT, Sanders, LH, Howlett, EH, Colton, MD, Germ, KE, Mayer, GD, Greenamyre, JT, and Meyer, JN. "PCR based determination of mitochondrial DNA copy number in multiple species." Methods in molecular biology (Clifton, N.J.) 1241 (January 2015): 23-38.
PMID
25308485
Source
epmc
Published In
Methods in molecular biology (Clifton, N.J.)
Volume
1241
Publish Date
2015
Start Page
23
End Page
38
DOI
10.1007/978-1-4939-1875-1_3

Mitochondrial Morphology and Fundamental Parameters of the Mitochondrial Respiratory Chain Are Altered in Caenorhabditis elegans Strains Deficient in Mitochondrial Dynamics and Homeostasis Processes.

Mitochondrial dysfunction has been linked to myriad human diseases and toxicant exposures, highlighting the need for assays capable of rapidly assessing mitochondrial health in vivo. Here, using the Seahorse XFe24 Analyzer and the pharmacological inhibitors dicyclohexylcarbodiimide and oligomycin (ATP-synthase inhibitors), carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (mitochondrial uncoupler) and sodium azide (cytochrome c oxidase inhibitor), we measured the fundamental parameters of mitochondrial respiratory chain function: basal oxygen consumption, ATP-linked respiration, maximal respiratory capacity, spare respiratory capacity and proton leak in the model organism Caenhorhabditis elegans. Since mutations in mitochondrial homeostasis genes cause mitochondrial dysfunction and have been linked to human disease, we measured mitochondrial respiratory function in mitochondrial fission (drp-1)-, fusion (fzo-1)-, mitophagy (pdr-1, pink-1)-, and electron transport chain complex III (isp-1)-deficient C. elegans. All showed altered function, but the nature of the alterations varied between the tested strains. We report increased basal oxygen consumption in drp-1; reduced maximal respiration in drp-1, fzo-1, and isp-1; reduced spare respiratory capacity in drp-1 and fzo-1; reduced proton leak in fzo-1 and isp-1; and increased proton leak in pink-1 nematodes. As mitochondrial morphology can play a role in mitochondrial energetics, we also quantified the mitochondrial aspect ratio for each mutant strain using a novel method, and for the first time report increased aspect ratios in pdr-1- and pink-1-deficient nematodes.

Authors
Luz, AL; Rooney, JP; Kubik, LL; Gonzalez, CP; Song, DH; Meyer, JN
MLA Citation
Luz, AL, Rooney, JP, Kubik, LL, Gonzalez, CP, Song, DH, and Meyer, JN. "Mitochondrial Morphology and Fundamental Parameters of the Mitochondrial Respiratory Chain Are Altered in Caenorhabditis elegans Strains Deficient in Mitochondrial Dynamics and Homeostasis Processes." PloS one 10.6 (January 2015): e0130940-.
PMID
26106885
Source
epmc
Published In
PloS one
Volume
10
Issue
6
Publish Date
2015
Start Page
e0130940
DOI
10.1371/journal.pone.0130940

Mitochondria, energetics, epigenetics, and cellular responses to stress.

Cells respond to environmental stressors through several key pathways, including response to reactive oxygen species (ROS), nutrient and ATP sensing, DNA damage response (DDR), and epigenetic alterations. Mitochondria play a central role in these pathways not only through energetics and ATP production but also through metabolites generated in the tricarboxylic acid cycle, as well as mitochondria-nuclear signaling related to mitochondria morphology, biogenesis, fission/fusion, mitophagy, apoptosis, and epigenetic regulation.We investigated the concept of bidirectional interactions between mitochondria and cellular pathways in response to environmental stress with a focus on epigenetic regulation, and we examined DNA repair and DDR pathways as examples of biological processes that respond to exogenous insults through changes in homeostasis and altered mitochondrial function.The National Institute of Environmental Health Sciences sponsored the Workshop on Mitochondria, Energetics, Epigenetics, Environment, and DNA Damage Response on 25-26 March 2013. Here, we summarize key points and ideas emerging from this meeting.A more comprehensive understanding of signaling mechanisms (cross-talk) between the mitochondria and nucleus is central to elucidating the integration of mitochondrial functions with other cellular response pathways in modulating the effects of environmental agents. Recent studies have highlighted the importance of mitochondrial functions in epigenetic regulation and DDR with environmental stress. Development and application of novel technologies, enhanced experimental models, and a systems-type research approach will help to discern how environmentally induced mitochondrial dysfunction affects key mechanistic pathways.Understanding mitochondria-cell signaling will provide insight into individual responses to environmental hazards, improving prediction of hazard and susceptibility to environmental stressors.

Authors
Shaughnessy, DT; McAllister, K; Worth, L; Haugen, AC; Meyer, JN; Domann, FE; Van Houten, B; Mostoslavsky, R; Bultman, SJ; Baccarelli, AA; Begley, TJ; Sobol, RW; Hirschey, MD; Ideker, T; Santos, JH; Copeland, WC; Tice, RR; Balshaw, DM; Tyson, FL
MLA Citation
Shaughnessy, DT, McAllister, K, Worth, L, Haugen, AC, Meyer, JN, Domann, FE, Van Houten, B, Mostoslavsky, R, Bultman, SJ, Baccarelli, AA, Begley, TJ, Sobol, RW, Hirschey, MD, Ideker, T, Santos, JH, Copeland, WC, Tice, RR, Balshaw, DM, and Tyson, FL. "Mitochondria, energetics, epigenetics, and cellular responses to stress." Environmental health perspectives 122.12 (December 2014): 1271-1278. (Review)
PMID
25127496
Source
epmc
Published In
Environmental health perspectives
Volume
122
Issue
12
Publish Date
2014
Start Page
1271
End Page
1278
DOI
10.1289/ehp.1408418

PCR based determination of mitochondrial DNA copy number in multiple species

© Springer Science+Business Media New York 2015. All rights are reserved.Mitochondrial DNA (mtDNA) copy number is a critical component of overall mitochondrial health. In this chapter, we describe methods for isolation of both mtDNA and nuclear DNA (nucDNA) and measurement of their respective copy numbers using quantitative PCR. Methods differ depending on the species and cell type of the starting material and availability of specific PCR reagents.

Authors
Rooney, JP; Ryde, IT; Sanders, LH; Howlett, EH; Colton, MD; Germ, KE; Mayer, GD; Greenamyre, JT; Meyer, JN
MLA Citation
Rooney, JP, Ryde, IT, Sanders, LH, Howlett, EH, Colton, MD, Germ, KE, Mayer, GD, Greenamyre, JT, and Meyer, JN. "PCR based determination of mitochondrial DNA copy number in multiple species." Mitochondrial Regulation: Methods and Protocols. October 11, 2014. 23-38.
Source
scopus
Publish Date
2014
Start Page
23
End Page
38
DOI
10.1007/978-1-4939-1875-1-3

Effects of 5'-fluoro-2-deoxyuridine on mitochondrial biology in Caenorhabditis elegans.

5-Fluoro-2'-deoxyuridine (FUdR) is a DNA synthesis inhibitor commonly used to sterilize Caenorhabditis elegans in order to maintain a synchronized aging population of nematodes, without contamination by their progeny, in lifespan experiments. All somatic cells in the adult nematode are post-mitotic and therefore do not require nuclear DNA synthesis. However, mitochondrial DNA (mtDNA) replicates independently of the cell cycle and thus represents a potential target for FUdR toxicity. Inhibition of mtDNA synthesis can lead to mtDNA depletion, which is linked to a number of diseases in humans. Furthermore, alterations in mitochondrial biology can affect lifespan in C. elegans. We characterized the effects of FUdR exposure on mtDNA and nuclear DNA (nucDNA) copy numbers, DNA damage, steady state ATP levels, nematode size, mitochondrial morphology, and lifespan in the germ line deficient JK1107 glp-1(q244) and PE255 glp-4(bn2) strains. Lifespan was increased very slightly by 25 μM FUdR, but was reduced by 400 μM. Both concentrations reduced mtDNA and nucDNA copy numbers, but did not change their ratio. There was no detectable effect of FUdR on mitochondrial morphology. Although both concentrations of FUdR resulted in smaller sized animals, changes to steady-state ATP levels were either not detected or restricted to the higher dose and/or later timepoints, depending on the method employed and strain tested. Finally, we determined the half-life of mtDNA in somatic cells of adult C. elegans to be between 8 and 13 days; this long half-life very likely explains the small or undetectable impact of FUdR on mitochondrial endpoints in our experiments. We discuss the relative pitfalls associated with using FUdR and germline deficient mutant strains as tools for the experimental elimination of progeny.

Authors
Rooney, JP; Luz, AL; González-Hunt, CP; Bodhicharla, R; Ryde, IT; Anbalagan, C; Meyer, JN
MLA Citation
Rooney, JP, Luz, AL, González-Hunt, CP, Bodhicharla, R, Ryde, IT, Anbalagan, C, and Meyer, JN. "Effects of 5'-fluoro-2-deoxyuridine on mitochondrial biology in Caenorhabditis elegans." Experimental gerontology 56 (August 2014): 69-76.
PMID
24704715
Source
epmc
Published In
Experimental Gerontology
Volume
56
Publish Date
2014
Start Page
69
End Page
76
DOI
10.1016/j.exger.2014.03.021

Comparative toxicity of silver nanoparticles on oxidative stress and DNA damage in the nematode, Caenorhabditis elegans.

This study examined the effects of polyvinylpyrrolidone (PVP) surface coating and size on the organismal and molecular toxicity of silver nanoparticles (AgNPs) on the nematode, Caenorhabditis elegans. The toxicity of bare AgNPs and 8 and 38 nm PVP-coated AgNPs (PVP8-AgNPs, PVP38-AgNPs) were compared. The toxicity of AgNO3 was also tested because ion dissolution and particle-specific effects are often important characteristics determining Ag nanotoxicity. Comparative toxicity across AgNO3 and the three different types of AgNPs was first evaluated using a C. elegans mortality test by a direct comparison of the LC50 values. Subsequently, mutant screening followed by oxidative stress, mitochondrial toxicity and DNA damage assays were carried out at equitoxic (LC10 and LC50) concentrations to further assess the toxicity mechanism of AgNO3 and AgNPs. AgNO3 and bare AgNPs had similar toxicities, whereas PVP coating reduced the toxicity of the AgNPs significantly. Of the PVP-AgNPs, the smaller NPs were more toxic. Different groups of mutants responded differently to AgNO3 and AgNPs, which indicates that their toxicity mechanism might be different. AgNO3 and bare AgNPs induced mitochondrial membrane damage. None of the silver materials tested caused detectable polymerase-inhibiting DNA lesions in either the nucleus or mitochondria as measured by a quantitative PCR assay, but AgNO3, bare AgNPs and PVP8-AgNPs induced oxidative DNA damage. These results show that coatings on the AgNPs surface and the particle size make a clear contribution to the toxicity of the AgNPs, and oxidative stress-related mitochondrial and DNA damage appear to be potential mechanisms of toxicity.

Authors
Ahn, J-M; Eom, H-J; Yang, X; Meyer, JN; Choi, J
MLA Citation
Ahn, J-M, Eom, H-J, Yang, X, Meyer, JN, and Choi, J. "Comparative toxicity of silver nanoparticles on oxidative stress and DNA damage in the nematode, Caenorhabditis elegans." Chemosphere 108 (August 2014): 343-352.
PMID
24726479
Source
epmc
Published In
Chemosphere
Volume
108
Publish Date
2014
Start Page
343
End Page
352
DOI
10.1016/j.chemosphere.2014.01.078

Developmental toxicity and DNA damage from exposure to parking lot runoff retention pond samples in the Japanese medaka (Oryzias latipes).

Parking lot runoff retention ponds (PLRRP) receive significant chemical input, but the biological effects of parking lot runoff are not well understood. We used the Japanese medaka (Oryzias latipes) as a model to study the toxicity of water and sediment samples from a PLRRP in Morehead City, NC. Medaka exposed in ovo to a dilution series of PLRRP water had increased odds of death before hatching, but not teratogenesis or delayed hatching. Next, we adapted a long-amplicon quantitative PCR (LA-QPCR) assay for DNA damage for use with the Japanese medaka. We employed LA-QPCR to test the hypotheses that PLRRP water and sediments would cause nuclear and mitochondrial DNA damage with and without full-spectrum, natural solar radiation. Fluoranthene with and without natural sunlight was a positive control for phototoxic polycyclic aromatic hydrocarbon-induced DNA damage. Fluoranthene exposure did not result in detectable DNA damage by itself, but in combination with sunlight caused significant DNA damage to both genomes. PLRRP samples caused DNA damage to both genomes, and this was not increased by sunlight exposure, suggesting the DNA damage was unlikely the result of PAH phototoxicity. We report for the first time that PLRRP-associated pollutants cause both nuclear and mitochondrial DNA damage, and that fluoranthene-mediated phototoxicity results in similar levels of damage to the nuclear and mitochondrial genomes. These effects may be especially significant in sensitive marine ecosystems.

Authors
Colton, MD; Kwok, KWH; Brandon, JA; Warren, IH; Ryde, IT; Cooper, EM; Hinton, DE; Rittschof, D; Meyer, JN
MLA Citation
Colton, MD, Kwok, KWH, Brandon, JA, Warren, IH, Ryde, IT, Cooper, EM, Hinton, DE, Rittschof, D, and Meyer, JN. "Developmental toxicity and DNA damage from exposure to parking lot runoff retention pond samples in the Japanese medaka (Oryzias latipes)." Marine environmental research 99 (August 2014): 117-124.
PMID
24816191
Source
epmc
Published In
Marine Environmental Research
Volume
99
Publish Date
2014
Start Page
117
End Page
124
DOI
10.1016/j.marenvres.2014.04.007

DEPDC1/LET-99 participates in an evolutionarily conserved pathway for anti-tubulin drug-induced apoptosis.

Microtubule-targeting chemotherapeutics induce apoptosis in cancer cells by promoting the phosphorylation and degradation of the anti-apoptotic BCL-2 family member MCL1. The signalling cascade linking microtubule disruption to MCL1 degradation remains however to be defined. Here, we establish an in vivo screening strategy in Caenorhabditis elegans to uncover genes involved in chemotherapy-induced apoptosis. Using an RNAi-based screen, we identify three genes required for vincristine-induced apoptosis. We show that the DEP domain protein LET-99 acts upstream of the heterotrimeric G protein alpha subunit GPA-11 to control activation of the stress kinase JNK-1. The human homologue of LET-99, DEPDC1, similarly regulates vincristine-induced cell death by promoting JNK-dependent degradation of the BCL-2 family protein MCL1. Collectively, these data uncover an evolutionarily conserved mediator of anti-tubulin drug-induced apoptosis and suggest that DEPDC1 levels could be an additional determinant for therapy response upstream of MCL1.

Authors
Sendoel, A; Maida, S; Zheng, X; Teo, Y; Stergiou, L; Rossi, C-A; Subasic, D; Pinto, SM; Kinchen, JM; Shi, M; Boettcher, S; Meyer, JN; Manz, MG; Bano, D; Hengartner, MO
MLA Citation
Sendoel, A, Maida, S, Zheng, X, Teo, Y, Stergiou, L, Rossi, C-A, Subasic, D, Pinto, SM, Kinchen, JM, Shi, M, Boettcher, S, Meyer, JN, Manz, MG, Bano, D, and Hengartner, MO. "DEPDC1/LET-99 participates in an evolutionarily conserved pathway for anti-tubulin drug-induced apoptosis." Nature cell biology 16.8 (August 2014): 812-820.
PMID
25064737
Source
epmc
Published In
Nature Cell Biology
Volume
16
Issue
8
Publish Date
2014
Start Page
812
End Page
820
DOI
10.1038/ncb3010

Response to Comment on “Sulfidation of Silver Nanoparticles: Natural Antidote to Their Toxicity”

Authors
Levard, C; Yang, X; Meyer, JN; Lowry, GV
MLA Citation
Levard, C, Yang, X, Meyer, JN, and Lowry, GV. "Response to Comment on “Sulfidation of Silver Nanoparticles: Natural Antidote to Their Toxicity”." Environmental Science & Technology 48.10 (May 20, 2014): 6051-6052.
Source
crossref
Published In
Environmental Science & Technology
Volume
48
Issue
10
Publish Date
2014
Start Page
6051
End Page
6052
DOI
10.1021/es500991r

Silver nanoparticle behavior, uptake, and toxicity in Caenorhabditis elegans: effects of natural organic matter.

Significant progress has been made in understanding the toxicity of silver nanoparticles (Ag NPs) under carefully controlled laboratory conditions. Natural organic matter (NOM) is omnipresent in complex environmental systems, where it may alter the behavior of nanoparticles in these systems. We exposed the nematode Caenorhabditis elegans to Ag NP suspensions with or without one of two kinds of NOM, Suwannee River and Pony Lake fulvic acids (SRFA and PLFA, respectively). PLFA rescued toxicity more effectively than SRFA. Measurement of total tissue silver content indicated that PLFA reduced total organismal (including digestive tract) uptake of ionic silver, but not of citrate-coated Ag NPs (CIT-Ag NPs). The majority of the CIT-Ag NP uptake was in the digestive tract. Limited tissue uptake was detected by hyperspectral microscopy but not by transmission electron microscopy. Co-exposure to PLFA resulted in the formation of NOM-Ag NP composites (both in medium and in nematodes) and rescued AgNO3- and CIT-Ag NP-induced cellular damage, potentially by decreasing intracellular uptake of CIT-Ag NPs.

Authors
Yang, X; Jiang, C; Hsu-Kim, H; Badireddy, AR; Dykstra, M; Wiesner, M; Hinton, DE; Meyer, JN
MLA Citation
Yang, X, Jiang, C, Hsu-Kim, H, Badireddy, AR, Dykstra, M, Wiesner, M, Hinton, DE, and Meyer, JN. "Silver nanoparticle behavior, uptake, and toxicity in Caenorhabditis elegans: effects of natural organic matter." Environmental science & technology 48.6 (March 10, 2014): 3486-3495.
PMID
24568198
Source
epmc
Published In
Environmental Science & Technology
Volume
48
Issue
6
Publish Date
2014
Start Page
3486
End Page
3495
DOI
10.1021/es404444n

Comparative toxicity of silver nanoparticles on oxidative stress and DNA damage in the nematode, Caenorhabditis elegans

This study examined the effects of polyvinylpyrrolidone (PVP) surface coating and size on the organismal and molecular toxicity of silver nanoparticles (AgNPs) on the nematode, Caenorhabditis elegans. The toxicity of bare AgNPs and 8 and 38nm PVP-coated AgNPs (PVP8-AgNPs, PVP38-AgNPs) were compared. The toxicity of AgNO3 was also tested because ion dissolution and particle-specific effects are often important characteristics determining Ag nanotoxicity. Comparative toxicity across AgNO3 and the three different types of AgNPs was first evaluated using a C. elegans mortality test by a direct comparison of the LC50 values. Subsequently, mutant screening followed by oxidative stress, mitochondrial toxicity and DNA damage assays were carried out at equitoxic (LC10 and LC50) concentrations to further assess the toxicity mechanism of AgNO3 and AgNPs. AgNO3 and bare AgNPs had similar toxicities, whereas PVP coating reduced the toxicity of the AgNPs significantly. Of the PVP-AgNPs, the smaller NPs were more toxic. Different groups of mutants responded differently to AgNO3 and AgNPs, which indicates that their toxicity mechanism might be different. AgNO3 and bare AgNPs induced mitochondrial membrane damage. None of the silver materials tested caused detectable polymerase-inhibiting DNA lesions in either the nucleus or mitochondria as measured by a quantitative PCR assay, but AgNO3, bare AgNPs and PVP8-AgNPs induced oxidative DNA damage. These results show that coatings on the AgNPs surface and the particle size make a clear contribution to the toxicity of the AgNPs, and oxidative stress-related mitochondrial and DNA damage appear to be potential mechanisms of toxicity. © 2014 Elsevier Ltd.

Authors
Ahn, JM; Eom, HJ; Yang, X; Meyer, JN; Choi, J
MLA Citation
Ahn, JM, Eom, HJ, Yang, X, Meyer, JN, and Choi, J. "Comparative toxicity of silver nanoparticles on oxidative stress and DNA damage in the nematode, Caenorhabditis elegans." Chemosphere 108 (January 1, 2014): 343-352.
Source
scopus
Published In
Chemosphere
Volume
108
Publish Date
2014
Start Page
343
End Page
352
DOI
10.1016/j.chemosphere.2014.01.078

Effects of 5'-fluoro-2-deoxyuridine on mitochondrial biology in Caenorhabditis elegans

5-Fluoro-2'-deoxyuridine (FUdR) is a DNA synthesis inhibitor commonly used to sterilize Caenorhabditis elegans in order to maintain a synchronized aging population of nematodes, without contamination by their progeny, in lifespan experiments. All somatic cells in the adult nematode are post-mitotic and therefore do not require nuclear DNA synthesis. However, mitochondrial DNA (mtDNA) replicates independently of the cell cycle and thus represents a potential target for FUdR toxicity. Inhibition of mtDNA synthesis can lead to mtDNA depletion, which is linked to a number of diseases in humans. Furthermore, alterations in mitochondrial biology can affect lifespan in C. elegans. We characterized the effects of FUdR exposure on mtDNA and nuclear DNA (nucDNA) copy numbers, DNA damage, steady state ATP levels, nematode size, mitochondrial morphology, and lifespan in the germ line deficient JK1107 glp-1(q244) and PE255 glp-4(bn2) strains. Lifespan was increased very slightly by 25. μM FUdR, but was reduced by 400. μM. Both concentrations reduced mtDNA and nucDNA copy numbers, but did not change their ratio. There was no detectable effect of FUdR on mitochondrial morphology. Although both concentrations of FUdR resulted in smaller sized animals, changes to steady-state ATP levels were either not detected or restricted to the higher dose and/or later timepoints, depending on the method employed and strain tested. Finally, we determined the half-life of mtDNA in somatic cells of adult C. elegans to be between 8 and 13. days; this long half-life very likely explains the small or undetectable impact of FUdR on mitochondrial endpoints in our experiments. We discuss the relative pitfalls associated with using FUdR and germline deficient mutant strains as tools for the experimental elimination of progeny. © 2014 Elsevier Inc.

Authors
Rooney, JP; Luz, AL; González-Hunt, CP; Bodhicharla, R; Ryde, IT; Anbalagan, C; Meyer, JN
MLA Citation
Rooney, JP, Luz, AL, González-Hunt, CP, Bodhicharla, R, Ryde, IT, Anbalagan, C, and Meyer, JN. "Effects of 5'-fluoro-2-deoxyuridine on mitochondrial biology in Caenorhabditis elegans." Experimental Gerontology 56 (January 1, 2014): 69-76.
Source
scopus
Published In
Experimental Gerontology
Volume
56
Publish Date
2014
Start Page
69
End Page
76
DOI
10.1016/j.exger.2014.03.021

Developmental toxicity and DNA damage from exposure to parking lot runoff retention pond samples in the Japanese medaka (Oryzias latipes)

Parking lot runoff retention ponds (PLRRP) receive significant chemical input, but the biological effects of parking lot runoff are not well understood. We used the Japanese medaka (Oryzias latipes) as a model to study the toxicity of water and sediment samples from a PLRRP in Morehead City, NC. Medaka exposed in ovo to a dilution series of PLRRP water had increased odds of death before hatching, but not teratogenesis or delayed hatching. Next, we adapted a long-amplicon quantitative PCR (LA-QPCR) assay for DNA damage for use with the Japanese medaka. We employed LA-QPCR to test the hypotheses that PLRRP water and sediments would cause nuclear and mitochondrial DNA damage with and without full-spectrum, natural solar radiation. Fluoranthene with and without natural sunlight was a positive control for phototoxic polycyclic aromatic hydrocarbon-induced DNA damage. Fluoranthene exposure did not result in detectable DNA damage by itself, but in combination with sunlight caused significant DNA damage to both genomes. PLRRP samples caused DNA damage to both genomes, and this was not increased by sunlight exposure, suggesting the DNA damage was unlikely the result of PAH phototoxicity. We report for the first time that PLRRP-associated pollutants cause both nuclear and mitochondrial DNA damage, and that fluoranthene-mediated phototoxicity results in similar levels of damage to the nuclear and mitochondrial genomes. These effects may be especially significant in sensitive marine ecosystems. © 2014 Elsevier Ltd.

Authors
Colton, MD; Kwok, KWH; Brandon, JA; Warren, IH; Ryde, IT; Cooper, EM; Hinton, DE; Rittschof, D; Meyer, JN
MLA Citation
Colton, MD, Kwok, KWH, Brandon, JA, Warren, IH, Ryde, IT, Cooper, EM, Hinton, DE, Rittschof, D, and Meyer, JN. "Developmental toxicity and DNA damage from exposure to parking lot runoff retention pond samples in the Japanese medaka (Oryzias latipes)." Marine Environmental Research 99 (January 1, 2014): 117-124.
Source
scopus
Published In
Marine Environmental Research
Volume
99
Publish Date
2014
Start Page
117
End Page
124
DOI
10.1016/j.marenvres.2014.04.007

DEPDC1/LET-99 participates in an evolutionarily conserved pathway for anti-tubulin drug-induced apoptosis

Microtubule-targeting chemotherapeutics induce apoptosis in cancer cells by promoting the phosphorylation and degradation of the anti-apoptotic BCL-2 family member MCL1. The signalling cascade linking microtubule disruption to MCL1 degradation remains however to be defined. Here, we establish an in vivo screening strategy in Caenorhabditis elegans to uncover genes involved in chemotherapy-induced apoptosis. Using an RNAi-based screen, we identify three genes required for vincristine-induced apoptosis. We show that the DEP domain protein LET-99 acts upstream of the heterotrimeric G protein alpha subunit GPA-11 to control activation of the stress kinase JNK-1. The human homologue of LET-99, DEPDC1, similarly regulates vincristine-induced cell death by promoting JNK-dependent degradation of the BCL-2 family protein MCL1. Collectively, these data uncover an evolutionarily conserved mediator of anti-tubulin drug-induced apoptosis and suggest that DEPDC1 levels could be an additional determinant for therapy response upstream of MCL1. © 2014 Macmillan Publishers Limited. All rights reserved.

Authors
Sendoel, A; Maida, S; Zheng, X; Teo, Y; Stergiou, L; Rossi, CA; Subasic, D; Pinto, SM; Kinchen, JM; Shi, M; Boettcher, S; Meyer, JN; Manz, MG; Bano, D; Hengartner, MO
MLA Citation
Sendoel, A, Maida, S, Zheng, X, Teo, Y, Stergiou, L, Rossi, CA, Subasic, D, Pinto, SM, Kinchen, JM, Shi, M, Boettcher, S, Meyer, JN, Manz, MG, Bano, D, and Hengartner, MO. "DEPDC1/LET-99 participates in an evolutionarily conserved pathway for anti-tubulin drug-induced apoptosis." Nature Cell Biology 16.8 (January 1, 2014): 812-820.
Source
scopus
Published In
Nature Cell Biology
Volume
16
Issue
8
Publish Date
2014
Start Page
812
End Page
820
DOI
10.1038/ncb3010

Cellular toxicity associated with exposure to perfluorinated carboxylates (PFCAs) and their metabolic precursors.

The biotransformation of fluorotelomer based compounds yields saturated and unsaturated fluorotelomer aldehydes (FTALs and FTUALs, respectively) and carboxylic acids (FTCAs and FTUCAs, respectively) as intermediate metabolites that subsequently transform to perfluorinated carboxylic acids (PFCAs). Previous studies have demonstrated that the FTCAs and FTUCAs are 1 to 5 orders of magnitude more toxic than PFCAs after exposure to aquatic organisms. Additionally, FTUALs have demonstrated reactivity with proteins, which may be associated with toxicity through the inhibition of protein function. The purpose of this study was to carry out a comprehensive assessment of the relative toxicity between PFCAs and their intermediate precursor metabolites: the FTALs, FTUALs, FTCAs, and FTUCAs. Analytes were separately incubated with human liver epithelial (THLE-2) cells to assess how varying the functional group and the fluorinated chain length affects cell viability. For each analyte, dose-response EC50 values were calculated. The EC50 values for FTUCAs and FTCAs were similar, with values ranging from 22 ± 9 and 24 ± 9 μM for the 10:2 congeners to 1004 ± 20 and 1004 ± 24 μM for the 4:2 congeners, respectively. The EC50 values for the PFCAs ranged from 65 ± 41 (PFDA) to 1361 ± 146 (PFBA) μM. The range of toxicity between PFCAs and their acid precursors were similar. However, the comparative toxicity between the 6:2 and 8:2 congeners and their corresponding PFCA had toxicity thresholds that varied depending on the functional headgroup, where FTUALs ≥ FTALs > FTUCAs ≥ FTCAs > PFCAs. For all PFCAs and acid precursors, toxicity depended on the length of the fluorinated chain, where the longer chain lengths yielded greater bioaccumulation and enhanced toxicity, results which agreed with those previously reported. By contrast, FTALs and FTUALs were the most toxic of all the analytes examined, where toxicity was enhanced at shorter chain lengths, with EC50 values of 7 ± 1 μM (6:2 FTUAL) and 8.6 ± 0.8 μM (6:2 FTAL). DNA adducts were not detectable for the aldehyde precursors, using a quantitative long-range PCR method. Our data provide the first evidence that aldehyde intermediates have demonstrated toxicity in cellular systems that is more significant than PFCAs and their corresponding acid intermediates.

Authors
Rand, AA; Rooney, JP; Butt, CM; Meyer, JN; Mabury, SA
MLA Citation
Rand, AA, Rooney, JP, Butt, CM, Meyer, JN, and Mabury, SA. "Cellular toxicity associated with exposure to perfluorinated carboxylates (PFCAs) and their metabolic precursors." Chemical research in toxicology 27.1 (January 2014): 42-50.
PMID
24299273
Source
epmc
Published In
Chemical Research in Toxicology
Volume
27
Issue
1
Publish Date
2014
Start Page
42
End Page
50
DOI
10.1021/tx400317p

Quantitative PCR-based measurement of nuclear and mitochondrial DNA damage and repair in mammalian cells.

In this chapter, we describe a gene-specific quantitative PCR (QPCR)-based assay for the measurement of DNA damage, using amplification of long DNA targets. This assay has been used extensively to measure the integrity of both nuclear and mitochondrial genomes exposed to different genotoxins and has proven to be particularly valuable in identifying reactive oxygen species-mediated mitochondrial DNA damage. QPCR can be used to quantify both the formation of DNA damage as well as the kinetics of damage removal. One of the main strengths of the assay is that it permits monitoring the integrity of mtDNA directly from total cellular DNA without the need for isolating mitochondria or a separate step of mitochondrial DNA purification. Here we discuss advantages and limitations of using QPCR to assay DNA damage in mammalian cells. In addition, we give a detailed protocol of the QPCR assay that helps facilitate its successful deployment in any molecular biology laboratory.

Authors
Furda, A; Santos, JH; Meyer, JN; Van Houten, B
MLA Citation
Furda, A, Santos, JH, Meyer, JN, and Van Houten, B. "Quantitative PCR-based measurement of nuclear and mitochondrial DNA damage and repair in mammalian cells." Methods in molecular biology (Clifton, N.J.) 1105 (January 2014): 419-437.
PMID
24623245
Source
epmc
Published In
Methods in molecular biology (Clifton, N.J.)
Volume
1105
Publish Date
2014
Start Page
419
End Page
437
DOI
10.1007/978-1-62703-739-6_31

Exposure to mitochondrial genotoxins and dopaminergic neurodegeneration in Caenorhabditis elegans.

Neurodegeneration has been correlated with mitochondrial DNA (mtDNA) damage and exposure to environmental toxins, but causation is unclear. We investigated the ability of several known environmental genotoxins and neurotoxins to cause mtDNA damage, mtDNA depletion, and neurodegeneration in Caenorhabditis elegans. We found that paraquat, cadmium chloride and aflatoxin B1 caused more mitochondrial than nuclear DNA damage, and paraquat and aflatoxin B1 also caused dopaminergic neurodegeneration. 6-hydroxydopamine (6-OHDA) caused similar levels of mitochondrial and nuclear DNA damage. To further test whether the neurodegeneration could be attributed to the observed mtDNA damage, C. elegans were exposed to repeated low-dose ultraviolet C radiation (UVC) that resulted in persistent mtDNA damage; this exposure also resulted in dopaminergic neurodegeneration. Damage to GABAergic neurons and pharyngeal muscle cells was not detected. We also found that fasting at the first larval stage was protective in dopaminergic neurons against 6-OHDA-induced neurodegeneration. Finally, we found that dopaminergic neurons in C. elegans are capable of regeneration after laser surgery. Our findings are consistent with a causal role for mitochondrial DNA damage in neurodegeneration, but also support non mtDNA-mediated mechanisms.

Authors
González-Hunt, CP; Leung, MCK; Bodhicharla, RK; McKeever, MG; Arrant, AE; Margillo, KM; Ryde, IT; Cyr, DD; Kosmaczewski, SG; Hammarlund, M; Meyer, JN
MLA Citation
González-Hunt, CP, Leung, MCK, Bodhicharla, RK, McKeever, MG, Arrant, AE, Margillo, KM, Ryde, IT, Cyr, DD, Kosmaczewski, SG, Hammarlund, M, and Meyer, JN. "Exposure to mitochondrial genotoxins and dopaminergic neurodegeneration in Caenorhabditis elegans." PloS one 9.12 (January 2014): e114459-.
PMID
25486066
Source
epmc
Published In
PloS one
Volume
9
Issue
12
Publish Date
2014
Start Page
e114459
DOI
10.1371/journal.pone.0114459

The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces mitochondrial and nuclear DNA damage in Caenorhabditis elegans.

The metabolites of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) form DNA adducts in animal models. While there are many reports of formation of nuclear DNA adducts, one report also detected NNK-induced damage to the mitochondrial genome in rats. Using a different DNA damage detection technology, we tested whether this finding could be repeated in the nematode Caenorhabditis elegans. We treated N2 strain (wild-type) nematodes with NNK in liquid culture, and applied quantitative PCR to analyze NNK-induced nuclear and mitochondrial DNA (mtDNA) damage. Our results confirm that NNK causes both nuclear and mtDNA damage. However, we did not detect a difference in the level of nuclear versus mtDNA damage in C. elegans. To test whether the mtDNA damage was associated with mitochondrial dysfunction, we used a transgenic nematode strain that permits in vivo measurement of ATP levels and found lower levels of ATP in NNK-exposed animals when compared with the unexposed controls. To test whether the lower levels of ATP could be attributed to inhibition of respiratory chain components, we investigated oxygen consumption in whole C. elegans and found reduced oxygen consumption in exposed animals when compared with the unexposed controls. Our data suggest a model in which NNK exposure causes damage to both C. elegans nuclear and mitochondrial genomes, and support the hypothesis that the mitochondrial damage is functionally important in this model. These results also represent a first step in developing this genetically tractable organism as a model for assessing NNK toxicity.

Authors
Bodhicharla, R; Ryde, IT; Prasad, GL; Meyer, JN
MLA Citation
Bodhicharla, R, Ryde, IT, Prasad, GL, and Meyer, JN. "The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces mitochondrial and nuclear DNA damage in Caenorhabditis elegans." Environ Mol Mutagen 55.1 (January 2014): 43-50.
PMID
24014178
Source
pubmed
Published In
Environmental and Molecular Mutagenesis
Volume
55
Issue
1
Publish Date
2014
Start Page
43
End Page
50
DOI
10.1002/em.21815

A micro-sized model for the in vivo study of nanoparticle toxicity: what has Caenorhabditis elegans taught us?

Authors
Choi, J; Tsyusko, OV; Unrine, JM; Chatterjee, N; Ahn, J-M; Yang, X; Thornton, BL; Ryde, IT; Starnes, D; Meyer, JN
MLA Citation
Choi, J, Tsyusko, OV, Unrine, JM, Chatterjee, N, Ahn, J-M, Yang, X, Thornton, BL, Ryde, IT, Starnes, D, and Meyer, JN. "A micro-sized model for the in vivo study of nanoparticle toxicity: what has Caenorhabditis elegans taught us?." Environmental Chemistry 11.3 (2014): 227-227.
Source
crossref
Published In
Environmental Chemistry
Volume
11
Issue
3
Publish Date
2014
Start Page
227
End Page
227
DOI
10.1071/EN13187

Developmental exposure to ultraviolet C radiation results in altered energy production later in life in Caenorhabditis elegans

Authors
Rooney, JP; Bodhicharla, R; Bess, AS; Leung, MCK; Ryde, IT; Ji, AQ; Meyer, JN
MLA Citation
Rooney, JP, Bodhicharla, R, Bess, AS, Leung, MCK, Ryde, IT, Ji, AQ, and Meyer, JN. "Developmental exposure to ultraviolet C radiation results in altered energy production later in life in Caenorhabditis elegans." MITOCHONDRION 13.6 (November 2013): 922-922.
Source
wos-lite
Published In
Mitochondrion
Volume
13
Issue
6
Publish Date
2013
Start Page
922
End Page
922
DOI
10.1016/j.mito.2013.07.063

Cerium oxide nanoparticles are more toxic than equimolar bulk cerium oxide in Caenorhabditis elegans.

Engineered cerium oxide nanoparticles (CeO2 NPs) are widely used in biomedical and engineering manufacturing industries. Previous research has shown the ability of CeO2 NPs to act as a redox catalyst, suggesting potential to both induce and alleviate oxidative stress in organisms. In this study, Caenorhabditis elegans and zebrafish (Danio rerio) were dosed with commercially available CeO2 NPs. Non-nano cerium oxide powder (CeO2) was used as a positive control for cerium toxicity. CeO2 NPs suspended in standard United States Environmental Protection Agency reconstituted moderately hard water, used to culture the C. elegans, quickly formed large polydisperse aggregates. Dosing solutions were renewed daily for 3 days. Exposure of wild-type nematodes resulted in dose-dependent growth inhibition detected for all 3 days (p < 0.0001). Non-nano CeO2 also caused significant growth inhibition (p < 0.0001), but the scale of inhibition was less at equivalent mass exposures compared with CeO2 NP exposure. Some metal and oxidative stress-sensitive mutant nematode strains showed mildly altered growth relative to the wild-type when dosed with 5 mg/L CeO2 NPs on days 2 and 3, thus providing weak evidence for a role for oxidative stress or metal sensitivity in CeO2 NP toxicity. Zebrafish microinjected with CeO2 NPs or CeO2 did not exhibit increased gross developmental defects compared with controls. Hyperspectral imaging showed that CeO2 NPs were ingested but not detectable inside the cells of C. elegans. Growth inhibition observed in C. elegans may be explained at least in part by a non-specific inhibition of feeding caused by CeO2 NPs aggregating around bacterial food and/or inside the gut tract.

Authors
Arnold, MC; Badireddy, AR; Wiesner, MR; Di Giulio, RT; Meyer, JN
MLA Citation
Arnold, MC, Badireddy, AR, Wiesner, MR, Di Giulio, RT, and Meyer, JN. "Cerium oxide nanoparticles are more toxic than equimolar bulk cerium oxide in Caenorhabditis elegans." Arch Environ Contam Toxicol 65.2 (August 2013): 224-233.
PMID
23619766
Source
pubmed
Published In
Archives of Environmental Contamination and Toxicology
Volume
65
Issue
2
Publish Date
2013
Start Page
224
End Page
233
DOI
10.1007/s00244-013-9905-5

Effects of early life exposure to ultraviolet C radiation on mitochondrial DNA content, transcription, ATP production, and oxygen consumption in developing Caenorhabditis elegans

Authors
Leung, MCK; Rooney, JP; Ryde, IT; Bernal, AJ; Bess, AS; Crocker, TL; Ji, AQ; Meyer, JN
MLA Citation
Leung, MCK, Rooney, JP, Ryde, IT, Bernal, AJ, Bess, AS, Crocker, TL, Ji, AQ, and Meyer, JN. "Effects of early life exposure to ultraviolet C radiation on mitochondrial DNA content, transcription, ATP production, and oxygen consumption in developing Caenorhabditis elegans." BMC PHARMACOLOGY & TOXICOLOGY 14 (February 4, 2013).
PMID
23374645
Source
wos-lite
Published In
BMC Pharmacology
Volume
14
Publish Date
2013
DOI
10.1186/2050-6511-14-9

Effects of mutations in mitochondrial dynamics-related genes on the mitochondrial response to ultraviolet C radiation in developing Caenorhabditis elegans.

We recently found that genes involved in mitochondrial dynamics and autophagy are required for removal of UVC-induced mitochondrial DNA damage. However, drp-1 and pink-1, unlike the autophagy and fusion genes tested, were not necessary for larval development after exposure. We hypothesized that increased fusion resulting from mutations in these genes facilitated recovery of mitochondrial function. In this work, we investigated this hypothesis by studying the effects of fis-1, fis-2, drp-1 and pink-1 mutations on mitochondrial responses to UVC exposure including ATP levels, mitochondrial DNA copy number, larval development and mitochondrial morphology. Our results suggest that mutations that promote highly networked mitochondria have the capacity to lessen the effects of mitochondrial genotoxicants on the function of this organelle.

Authors
Bess, AS; Leung, MCK; Ryde, IT; Rooney, JP; Hinton, DE; Meyer, JN
MLA Citation
Bess, AS, Leung, MCK, Ryde, IT, Rooney, JP, Hinton, DE, and Meyer, JN. "Effects of mutations in mitochondrial dynamics-related genes on the mitochondrial response to ultraviolet C radiation in developing Caenorhabditis elegans." Worm 2.1 (January 1, 2013): e23763-.
PMID
24058863
Source
pubmed
Published In
Worm
Volume
2
Issue
1
Publish Date
2013
Start Page
e23763
DOI
10.4161/worm.23763

UVC-induced mitochondrial degradation via autophagy correlates with mtDNA damage removal in primary human fibroblasts.

Mitochondrial DNA (mtDNA) is more susceptible than nuclear DNA to helix-distorting damage via exposure to environmental genotoxins, partially due to a lack of nucleotide excision repair. Thus, this damage is irreparable and persistent in mtDNA in the short term. We recently found that helix-distorting mtDNA damage induced by ultraviolet C radiation (UVC) is gradually removed in Caenorhabditis elegans and that removal is dependent upon autophagy and mitochondrial dynamics. We here report the effects of UVC exposure on mitophagy, mitochondrial morphology, and indicators of mitochondrial function in mammalian cells. Exposure to UVC induced autophagy within 24 h; nonetheless, significant mitochondrial degradation was not observed until 72 h post exposure. Mitochondrial mass, morphology, and function were not significantly altered. These data further support the idea that persistent mtDNA damage is removed by autophagy and also suggest a powerful compensatory capacity for dealing with mtDNA damage.

Authors
Bess, AS; Ryde, IT; Hinton, DE; Meyer, JN
MLA Citation
Bess, AS, Ryde, IT, Hinton, DE, and Meyer, JN. "UVC-induced mitochondrial degradation via autophagy correlates with mtDNA damage removal in primary human fibroblasts." J Biochem Mol Toxicol 27.1 (January 2013): 28-41.
PMID
23132756
Source
pubmed
Published In
Journal of Biochemical and Molecular Toxicology
Volume
27
Issue
1
Publish Date
2013
Start Page
28
End Page
41
DOI
10.1002/jbt.21440

Sulfidation of silver nanoparticles: natural antidote to their toxicity.

Nanomaterials are highly dynamic in biological and environmental media. A critical need for advancing environmental health and safety research for nanomaterials is to identify physical and chemical transformations that affect the nanomaterial properties and their toxicity. Silver nanoparticles, one of the most toxic and well-studied nanomaterials, readily react with sulfide to form Ag(0)/Ag2S core-shell particles. Here, we show that sulfidation decreased silver nanoparticle toxicity to four diverse types of aquatic and terrestrial eukaryotic organisms (Danio rerio (zebrafish), Fundulus heteroclitus (killifish), Caenorhabditis elegans (nematode worm), and the aquatic plant Lemna minuta (least duckweed)). Toxicity reduction, which was dramatic in killifish and duckweed even for low extents of sulfidation (about 2 mol % S), is primarily associated with a decrease in Ag(+) concentration after sulfidation due to the lower solubility of Ag2S relative to elemental Ag (Ag(0)). These results suggest that even partial sulfidation of AgNP will decrease the toxicity of AgNPs relative to their pristine counterparts. We also show that, for a given organism, the presence of chloride in the exposure media strongly affects the toxicity results by affecting Ag speciation. These results highlight the need to consider environmental transformations of NPs in assessing their toxicity to accurately portray their potential environmental risks.

Authors
Levard, C; Hotze, EM; Colman, BP; Dale, AL; Truong, L; Yang, XY; Bone, AJ; Brown, GE; Tanguay, RL; Di Giulio, RT; Bernhardt, ES; Meyer, JN; Wiesner, MR; Lowry, GV
MLA Citation
Levard, C, Hotze, EM, Colman, BP, Dale, AL, Truong, L, Yang, XY, Bone, AJ, Brown, GE, Tanguay, RL, Di Giulio, RT, Bernhardt, ES, Meyer, JN, Wiesner, MR, and Lowry, GV. "Sulfidation of silver nanoparticles: natural antidote to their toxicity." Environ Sci Technol 47.23 (2013): 13440-13448.
PMID
24180218
Source
pubmed
Published In
Environmental Science & Technology
Volume
47
Issue
23
Publish Date
2013
Start Page
13440
End Page
13448
DOI
10.1021/es403527n

UVC-Induced Mitochondrial Degradation via Autophagy Correlates with mtDNA Damage Removal in Primary Human Fibroblasts

Mitochondrial DNA (mtDNA) is more susceptible than nuclear DNA to helix-distorting damage via exposure to environmental genotoxins, partially due to a lack of nucleotide excision repair. Thus, this damage is irreparable and persistent in mtDNA in the short term. We recently found that helix-distorting mtDNA damage induced by ultraviolet C radiation (UVC) is gradually removed in Caenorhabditis elegans and that removal is dependent upon autophagy and mitochondrial dynamics. We here report the effects of UVC exposure on mitophagy, mitochondrial morphology, and indicators of mitochondrial function in mammalian cells. Exposure to UVC induced autophagy within 24 h; nonetheless, significant mitochondrial degradation was not observed until 72 h post exposure. Mitochondrial mass, morphology, and function were not significantly altered. These data further support the idea that persistent mtDNA damage is removed by autophagy and also suggest a powerful compensatory capacity for dealing with mtDNA damage. © 2012 Wiley Periodicals, Inc.

Authors
Bess, AS; Ryde, IT; Hinton, DE; Meyer, JN
MLA Citation
Bess, AS, Ryde, IT, Hinton, DE, and Meyer, JN. "UVC-Induced Mitochondrial Degradation via Autophagy Correlates with mtDNA Damage Removal in Primary Human Fibroblasts." Journal of Biochemical and Molecular Toxicology 27.1 (2013): 28-41.
Source
scival
Published In
Journal of Biochemical and Molecular Toxicology
Volume
27
Issue
1
Publish Date
2013
Start Page
28
End Page
41
DOI
10.1002/jbt.21440

Cerium oxide nanoparticles are more toxic than equimolar bulk cerium oxide in caenorhabditis elegans

Engineered cerium oxide nanoparticles (CeO2 NPs) are widely used in biomedical and engineering manufacturing industries. Previous research has shown the ability of CeO2 NPs to act as a redox catalyst, suggesting potential to both induce and alleviate oxidative stress in organisms. In this study, Caenorhabditis elegans and zebrafish (Danio rerio) were dosed with commercially available CeO2 NPs. Non-nano cerium oxide powder (CeO2) was used as a positive control for cerium toxicity. CeO 2 NPs suspended in standard United States Environmental Protection Agency reconstituted moderately hard water, used to culture the C. elegans, quickly formed large polydisperse aggregates. Dosing solutions were renewed daily for 3 days. Exposure of wild-type nematodes resulted in dose-dependent growth inhibition detected for all 3 days (p < 0.0001). Non-nano CeO 2 also caused significant growth inhibition (p < 0.0001), but the scale of inhibition was less at equivalent mass exposures compared with CeO 2 NP exposure. Some metal and oxidative stress-sensitive mutant nematode strains showed mildly altered growth relative to the wild-type when dosed with 5 mg/L CeO2 NPs on days 2 and 3, thus providing weak evidence for a role for oxidative stress or metal sensitivity in CeO2 NP toxicity. Zebrafish microinjected with CeO2 NPs or CeO 2 did not exhibit increased gross developmental defects compared with controls. Hyperspectral imaging showed that CeO2 NPs were ingested but not detectable inside the cells of C. elegans. Growth inhibition observed in C. elegans may be explained at least in part by a non-specific inhibition of feeding caused by CeO2 NPs aggregating around bacterial food and/or inside the gut tract. © 2013 Springer Science+Business Media New York.

Authors
Arnold, MC; Badireddy, AR; Wiesner, MR; Giulio, RTD; Meyer, JN
MLA Citation
Arnold, MC, Badireddy, AR, Wiesner, MR, Giulio, RTD, and Meyer, JN. "Cerium oxide nanoparticles are more toxic than equimolar bulk cerium oxide in caenorhabditis elegans." Archives of Environmental Contamination and Toxicology 65.2 (2013): 224-233.
Source
scival
Published In
Archives of Environmental Contamination and Toxicology
Volume
65
Issue
2
Publish Date
2013
Start Page
224
End Page
233
DOI
10.1007/s00244-013-9905-5

Mitochondria as a target of environmental toxicants

Enormous strides have recently been made in our understanding of the biology and pathobiology of mitochondria. Many diseases have been identified as caused by mitochondrial dysfunction, and many pharmaceuticals have been identified as previously unrecognized mitochondrial toxicants. A much smaller but growing literature indicates that mitochondria are also targeted by environmental pollutants. We briefly review the importance of mitochondrial function and maintenance for health based on the genetics of mitochondrial diseases and the toxicities resulting from pharmaceutical exposure. We then discuss how the principles of mitochondrial vulnerability illustrated by those fields might apply to environmental contaminants, with particular attention to factors that may modulate vulnerability including genetic differences, epigenetic interactions, tissue characteristics, and developmental stage. Finally, we review the literature related to environmental mitochondrial toxicants, with a particular focus on those toxicants that target mitochondrial DNA. We conclude that the fields of environmental toxicology and environmental health should focus more strongly on mitochondria. © The Author 2013.

Authors
Meyer, JN; Leung, MCK; Rooney, JP; Sendoel, A; Hengartner, MO; Kisby, GE; Bess, AS
MLA Citation
Meyer, JN, Leung, MCK, Rooney, JP, Sendoel, A, Hengartner, MO, Kisby, GE, and Bess, AS. "Mitochondria as a target of environmental toxicants." Toxicological Sciences 134.1 (2013): 1-17.
PMID
23629515
Source
scival
Published In
Toxicological Sciences (Elsevier)
Volume
134
Issue
1
Publish Date
2013
Start Page
1
End Page
17
DOI
10.1093/toxsci/kft102

Assessing different mechanisms of toxicity in mountaintop removal/valley fill coal mining-affected watershed samples using Caenorhabditis elegans.

Mountaintop removal-valley fill coal mining has been associated with a variety of impacts on ecosystem and human health, in particular reductions in the biodiversity of receiving streams. However, effluents emerging from valley fills contain a complex mixture of chemicals including metals, metalloids, and salts, and it is not clear which of these are the most important drivers of toxicity. We found that streamwater and sediment samples collected from mine-impacted streams of the Upper Mud River in West Virginia inhibited the growth of the nematode Caenorhabditis elegans. Next, we took advantage of genetic and transgenic tools available in this model organism to test the hypotheses that the toxicity could be attributed to metals, selenium, oxidative stress, or osmotic stress. Our results indicate that in general, the toxicity of streamwater to C. elegans was attributable to osmotic stress, while the toxicity of sediments resulted mostly from metals or metalloids.

Authors
Turner, EA; Kroeger, GL; Arnold, MC; Thornton, BL; Di Giulio, RT; Meyer, JN
MLA Citation
Turner, EA, Kroeger, GL, Arnold, MC, Thornton, BL, Di Giulio, RT, and Meyer, JN. "Assessing different mechanisms of toxicity in mountaintop removal/valley fill coal mining-affected watershed samples using Caenorhabditis elegans. (Published online)" PLoS One 8.9 (2013): e75329-.
PMID
24066176
Source
pubmed
Published In
PloS one
Volume
8
Issue
9
Publish Date
2013
Start Page
e75329
DOI
10.1371/journal.pone.0075329

Mechanism of silver nanoparticle toxicity is dependent on dissolved silver and surface coating in Caenorhabditis elegans.

The rapidly increasing use of silver nanoparticles (Ag NPs) in consumer products and medical applications has raised ecological and human health concerns. A key question for addressing these concerns is whether Ag NP toxicity is mechanistically unique to nanoparticulate silver, or if it is a result of the release of silver ions. Furthermore, since Ag NPs are produced in a large variety of monomer sizes and coatings, and since their physicochemical behavior depends on the media composition, it is important to understand how these variables modulate toxicity. We found that a lower ionic strength medium resulted in greater toxicity (measured as growth inhibition) of all tested Ag NPs to Caenorhabditis elegans and that both dissolved silver and coating influenced Ag NP toxicity. We found a linear correlation between Ag NP toxicity and dissolved silver, but no correlation between size and toxicity. We used three independent and complementary approaches to investigate the mechanisms of toxicity of differentially coated and sized Ag NPs: pharmacological (rescue with trolox and N-acetylcysteine), genetic (analysis of metal-sensitive and oxidative stress-sensitive mutants), and physicochemical (including analysis of dissolution of Ag NPs). Oxidative dissolution was limited in our experimental conditions (maximally 15% in 24 h) yet was key to the toxicity of most Ag NPs, highlighting a critical role for dissolved silver complexed with thiols in the toxicity of all tested Ag NPs. Some Ag NPs (typically less soluble due to size or coating) also acted via oxidative stress, an effect specific to nanoparticulate silver. However, in no case studied here was the toxicity of a Ag NP greater than would be predicted by complete dissolution of the same mass of silver as silver ions.

Authors
Yang, X; Gondikas, AP; Marinakos, SM; Auffan, M; Liu, J; Hsu-Kim, H; Meyer, JN
MLA Citation
Yang, X, Gondikas, AP, Marinakos, SM, Auffan, M, Liu, J, Hsu-Kim, H, and Meyer, JN. "Mechanism of silver nanoparticle toxicity is dependent on dissolved silver and surface coating in Caenorhabditis elegans." Environ Sci Technol 46.2 (January 17, 2012): 1119-1127.
PMID
22148238
Source
pubmed
Published In
Environmental Science & Technology
Volume
46
Issue
2
Publish Date
2012
Start Page
1119
End Page
1127
DOI
10.1021/es202417t

In vivo analysis of the ability of Caenorhabditis elegans to metabolize the human CYP3A and CYP1A2 diagnostic substrates testosterone and phenacetin

Authors
Meyer, JN
MLA Citation
Meyer, JN. "In vivo analysis of the ability of Caenorhabditis elegans to metabolize the human CYP3A and CYP1A2 diagnostic substrates testosterone and phenacetin (Accepted)." Worm Breeder's Gazette (2012). (Academic Article)
Source
manual
Published In
Worm Breeder's Gazette
Publish Date
2012

A call for fuller reporting of toxicity test data

Authors
Meyer, JN
MLA Citation
Meyer, JN. "A call for fuller reporting of toxicity test data (Accepted)." Integrated Environmental Assessment and Management (2012). (Academic Article)
PMID
23529809
Source
manual
Published In
Integrated Environmental Assessment and Management
Publish Date
2012

Analysis of DNA damage and repair in nuclear and mitochondrial DNA of animal cells using quantitative PCR

This chapter was written as a guide to using the long-amplicon quantitative PCR (QPCR) assay for the measurement of DNA damage in mammalian as well as nonmammalian species such as Caenorhabditis elegans (nematodes), Drosophila melanogaster (fruit flies), and two species of fish (Fundulus heteroclitus and Danio rerio). Since its development in the early 1990s (Kalinowski et al., Nucleic Acids Res 20:3485-3494, 1992; Salazar and Van Houten, Mutat Res 385:139-149, 1997; Yakes and Van Houten, Proc Natl Acad Sci USA 94:514-519, 1997), the QPCR assay has been widely used to measure DNA damage and repair kinetics in nuclear and mitochondrial genomes after genotoxin exposure (Yakes and Van Houten, Proc Natl Acad Sci USA 94:514-519, 1997; Santos et al., J Biol Chem 278:1728-1734, 2003; Mandavilli et al., Mol Brain Res 133:215-223, 2005). One of the main strengths of the assay is that the labor-intensive and artifact-generating step of mitochondrial isolation is not needed for the accurate measurement of mitochondrial DNA copy number and damage. Below we present the advantages and limitations of using QPCR to assay DNA damage in animal cells and provide a detailed protocol of the QPCR assay that integrates its usage in newly developed animal systems. © 2012 Springer Science+Business Media New York.

Authors
Furda, AM; Bess, AS; Meyer, JN; Houten, BV
MLA Citation
Furda, AM, Bess, AS, Meyer, JN, and Houten, BV. "Analysis of DNA damage and repair in nuclear and mitochondrial DNA of animal cells using quantitative PCR." Methods in Molecular Biology 920 (2012): 111-132.
PMID
22941600
Source
scival
Published In
Methods in molecular biology (Clifton, N.J.)
Volume
920
Publish Date
2012
Start Page
111
End Page
132
DOI
10.1007/978-1-61779-998-3-9

Human mitochondrial DNA polymerase γ exhibits potential for bypass and mutagenesis at UV-induced cyclobutane thymine dimers

Cyclobutane thymine dimers (T-T) comprise the majority of DNA damage caused by short wavelength ultraviolet radiation. These lesions generally block replicative DNA polymerases and are repaired by nucleotide excision repair or bypassed by translesion polymerases in the nucleus. Mitochondria lack nucleotide excision repair, and therefore, it is important to understand how the sole mitochondrial DNA polymerase, pol γ, interacts with irreparable lesions such as T-T. We performed in vitro DNA polymerization assays to measure the kinetics of incorporation opposite the lesion and bypass of the lesion by pol γ with a dimer-containing template. Exonuclease-deficient pol γ bypassed thymine dimers with low relative efficiency; bypass was attenuated but still detectable when using exonuclease-proficient pol γ. When bypass did occur, pol γ misincorporated a guanine residue opposite the 3′-thymine of the dimer only 4-fold less efficiently than it incorporated an adenine. Surprisingly, the pol γ exonuclease-proficient enzyme excised the incorrectly incorporated guanine at similar rates irrespective of the nature of the thymines in the template. In the presence of all four dNTPs, pol γ extended the primer after incorporation of two adenines opposite the lesion with relatively higher efficiency compared with extension past either an adenine or a guanine incorporated opposite the 3′-thymine of the T-T. Our results suggest that T-T usually stalls mitochondrial DNA replication but also suggest a mechanism for the introduction of point mutations and deletions in the mitochondrial genomes of chronically UV-exposed cells.

Authors
Kasiviswanathan, R; Gustafson, MA; Copeland, WC; Meyer, JN
MLA Citation
Kasiviswanathan, R, Gustafson, MA, Copeland, WC, and Meyer, JN. "Human mitochondrial DNA polymerase γ exhibits potential for bypass and mutagenesis at UV-induced cyclobutane thymine dimers." Journal of Biological Chemistry 287.12 (2012): 9222-9229.
PMID
22194617
Source
scival
Published In
The Journal of biological chemistry
Volume
287
Issue
12
Publish Date
2012
Start Page
9222
End Page
9229
DOI
10.1074/jbc.M111.306852

In vivo repair of alkylating and oxidative DNA damage in the mitochondrial and nuclear genomes of wild-type and glycosylase-deficient Caenorhabditis elegans

Base excision repair (BER) is an evolutionarily conserved DNA repair pathway that is critical for repair of many of the most common types of DNA damage generated both by endogenous metabolic pathways and exposure to exogenous stressors such as pollutants. Caenorhabditis elegans is an increasingly important model organism for the study of DNA damage-related processes including DNA repair, genotoxicity, and apoptosis, but BER is not well understood in this organism, and has not previously been measured in vivo. We report robust BER in the nuclear genome and slightly slower damage removal from the mitochondrial genome; in both cases the removal rates are comparable to those observed in mammals. However we could detect no deficiency in BER in the nth-1 strain, which carries a deletion in the only glycosylase yet described in C. elegans that repairs oxidative DNA damage. We also failed to detect increased lethality or growth inhibition in nth-1 nematodes after exposure to oxidative or alkylating damage, suggesting the existence of at least one additional as-yet undetected glycosylase. © 2012 Elsevier B.V.

Authors
Hunter, SE; Gustafson, MA; Margillo, KM; Lee, SA; Ryde, IT; Meyer, JN
MLA Citation
Hunter, SE, Gustafson, MA, Margillo, KM, Lee, SA, Ryde, IT, and Meyer, JN. "In vivo repair of alkylating and oxidative DNA damage in the mitochondrial and nuclear genomes of wild-type and glycosylase-deficient Caenorhabditis elegans." DNA Repair 11.11 (2012): 857-863.
PMID
22959841
Source
scival
Published In
DNA Repair
Volume
11
Issue
11
Publish Date
2012
Start Page
857
End Page
863
DOI
10.1016/j.dnarep.2012.08.002

Mitochondrial DNA-depleted A549 cells are resistant to bleomycin

Alveolar epithelial cells are considered to be the primary target of bleomycininduced lung injury, leading to interstitial fibrosis. The molecular mechanisms by which bleomycin causes this damage are poorly understood but are suspected to involve generation of reactive oxygen species and DNA damage. We studied the effect of bleomycin on mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) in human alveolar epithelial A549 cells. Bleomycin caused an increase in reactive oxygen species production, DNA damage, and apoptosis in A549 cells; however, bleomycin induced more mtDNA than nDNA damage. DNA damage was associated with activation of caspase-3, cleavage of poly(ADPribose) polymerase, and cleavage and activation of protein kinase D1 (PKD1), a newly identified mitochondrial oxidative stress sensor. These effects appear to be mtDNA-dependent, because no caspase-3 or PKD1 activation was observed in mtDNA-depleted (ρ°) A549 cells. Survival rate after bleomycin treatment was higher for A549 ρ° than A549 cells. These results suggest that A549 ρ° cells are more resistant to bleomycin toxicity than are parent A549 cells, likely in part due to the depletion of mtDNA and impairment of mitochondria-dependent apoptotic pathways.

Authors
Brar, SS; Meyer, JN; Bortner, CD; Houten, BV; II, WJM
MLA Citation
Brar, SS, Meyer, JN, Bortner, CD, Houten, BV, and II, WJM. "Mitochondrial DNA-depleted A549 cells are resistant to bleomycin." American Journal of Physiology - Lung Cellular and Molecular Physiology 303.5 (2012): L413-L424.
PMID
22773697
Source
scival
Published In
American journal of physiology. Lung cellular and molecular physiology
Volume
303
Issue
5
Publish Date
2012
Start Page
L413
End Page
L424
DOI
10.1152/ajplung.00343.2011

Mitochondrial dynamics and autophagy aid in removal of persistent mitochondrial DNA damage in Caenorhabditis elegans

Mitochondria lack the ability to repair certain helix-distorting lesions that are induced at high levels in mitochondrial DNA (mtDNA) by important environmental genotoxins and endogenous metabolites. These lesions are irreparable and persistent in the short term, but their long-term fate is unknown. We report that removal of such mtDNA damage is detectable by 48 h in Caenorhabditis elegans, and requires mitochondrial fusion, fission and autophagy, providing genetic evidence for a novel mtDNA damage removal pathway. Furthermore, mutations in genes involved in these processes as well as pharmacological inhibition of autophagy exacerbated mtDNA damage-mediated larval arrest, illustrating the in vivo relevance of removal of persistent mtDNA damage. Mutations in genes in these pathways exist in the human population, demonstrating the potential for important gene-environment interactions affecting mitochondrial health after genotoxin exposure. © 2012 The Author(s).

Authors
Bess, AS; Crocker, TL; Ryde, IT; Meyer, JN
MLA Citation
Bess, AS, Crocker, TL, Ryde, IT, and Meyer, JN. "Mitochondrial dynamics and autophagy aid in removal of persistent mitochondrial DNA damage in Caenorhabditis elegans." Nucleic Acids Research 40.16 (2012): 7916-7931.
PMID
22718972
Source
scival
Published In
Nucleic Acids Research
Volume
40
Issue
16
Publish Date
2012
Start Page
7916
End Page
7931
DOI
10.1093/nar/gks532

Involvement of autophagy and mitochondrial dynamics in determining the fate and effects of irreparable mitochondrial DNA damage

Mitochondrial DNA (mtDNA) is different in many ways from nuclear DNA. A key difference is that certain types of DNA damage are not repaired in the mitochondrial genome. What, then, is the fate of such damage? What are the effects? Both questions are important from a health perspective because irreparable mtDNA damage is caused by many common environmental stressors including ultraviolet C radiation (UVC). We found that UVC-induced mtDNA damage is removed slowly in the nematode Caenorhabditis elegans via a mechanism dependent on mitochondrial fusion, fission, and autophagy. However, knockdown or knockout of genes involved in these processes-many of which have homologs involved in human mitochondrial diseases-had very different effects on the organismal response to UVC. Reduced mitochondrial fission and autophagy caused no or small effects, while reduced mitochondrial fusion had dramatic effects. © 2012 Landes Bioscience.

Authors
Meyer, JN; Bess, AS
MLA Citation
Meyer, JN, and Bess, AS. "Involvement of autophagy and mitochondrial dynamics in determining the fate and effects of irreparable mitochondrial DNA damage." Autophagy 8.12 (2012): 1822-1823.
PMID
22929123
Source
scival
Published In
Autophagy
Volume
8
Issue
12
Publish Date
2012
Start Page
1822
End Page
1823
DOI
10.4161/auto.21741

Mitochondrial Dynamics and Autophagy Aid in Removal of Persistent Mitochondrial DNA Damage.

Authors
Bess, AS; Crocker, TL; Ryde, IT; Meyer, JN
MLA Citation
Bess, AS, Crocker, TL, Ryde, IT, and Meyer, JN. "Mitochondrial Dynamics and Autophagy Aid in Removal of Persistent Mitochondrial DNA Damage." October 2011.
Source
wos-lite
Published In
Environmental and Molecular Mutagenesis
Volume
52
Publish Date
2011
Start Page
S47
End Page
S47

Intracellular uptake and associated toxicity of silver nanoparticles in Caenorhabditis elegans.

Silver nanoparticles (AgNPs) are frequently used as antimicrobials. While the mechanism(s) by which AgNPs are toxic are unclear, their increasing use raises the concern that release into the environment could lead to environmental toxicity. We characterized the physicochemical behavior, uptake, toxicity (growth inhibition), and mechanism of toxicity of three AgNPs with different sizes and polyvinylpyrrolidone (PVP) or citrate coatings to the nematode Caenorhabditis elegans. We used wild-type (N2) C. elegans and strains expected to be sensitive to oxidative stress (nth-1, sod-2 and mev-1), genotoxins (xpa-1 and nth-1), and metals (mtl-2). Using traditional and novel analytical methods, we observed significant aggregation and extra-organismal dissolution of silver, organismal uptake and, in one case, transgenerational transfer of AgNPs. We also observed growth inhibition by all tested AgNPs at concentrations in the low mg/L levels. A metallothionein-deficient (mtl-2) strain was the only mutant tested that exhibited consistently greater AgNP sensitivity than wild-type. Although all tested AgNPs were internalized (passed cell membranes) in C. elegans, at least part of the toxicity observed was mediated by ionic silver. Finally, we describe a modified growth assay that permits differentiation between direct growth-inhibitory effects and indirect inhibition mediated by toxicity to the food source.

Authors
Meyer, JN; Lord, CA; Yang, XY; Turner, EA; Badireddy, AR; Marinakos, SM; Chilkoti, A; Wiesner, MR; Auffan, M
MLA Citation
Meyer, JN, Lord, CA, Yang, XY, Turner, EA, Badireddy, AR, Marinakos, SM, Chilkoti, A, Wiesner, MR, and Auffan, M. "Intracellular uptake and associated toxicity of silver nanoparticles in Caenorhabditis elegans." Aquat Toxicol 100.2 (October 15, 2010): 140-150.
PMID
20708279
Source
pubmed
Published In
Aquatic Toxicology
Volume
100
Issue
2
Publish Date
2010
Start Page
140
End Page
150
DOI
10.1016/j.aquatox.2010.07.016

The QPCR assay for analysis of mitochondrial DNA damage, repair, and relative copy number.

The quantitative polymerase chain reaction (QPCR) assay allows measurement of DNA damage in the mitochondrial and nuclear genomes without isolation of mitochondria. It also permits measurement of relative mitochondrial genome copy number. Finally, it can be used for measurement of DNA repair in vivo when employed appropriately. In this manuscript we briefly review the methodology of the QPCR assay, discuss its strengths and limitations, address considerations for measurement of mitochondrial DNA repair, and describe methodological changes implemented in recent years. We present QPCR assay primers and reaction conditions for five species not previously described in a methods article: Caenorhabditis elegans, Fundulus heteroclitus, Danio rerio, Drosophila melanogaster, and adenovirus. Finally, we illustrate the use of the assay by measuring repair of ultraviolet C radiation-induced DNA damage in the nuclear but not mitochondrial genomes of a zebrafish cell culture.

Authors
Hunter, SE; Jung, D; Di Giulio, RT; Meyer, JN
MLA Citation
Hunter, SE, Jung, D, Di Giulio, RT, and Meyer, JN. "The QPCR assay for analysis of mitochondrial DNA damage, repair, and relative copy number." Methods 51.4 (August 2010): 444-451. (Review)
PMID
20123023
Source
pubmed
Published In
Methods
Volume
51
Issue
4
Publish Date
2010
Start Page
444
End Page
451
DOI
10.1016/j.ymeth.2010.01.033

Quantifying Mitochondrial and Nuclear DNA Damage in Sentinel Species

Authors
Meyer, JN; Jung, D; Di Giulio, RT
MLA Citation
Meyer, JN, Jung, D, and Di Giulio, RT. "Quantifying Mitochondrial and Nuclear DNA Damage in Sentinel Species." August 2010.
Source
wos-lite
Published In
Environmental and Molecular Mutagenesis
Volume
51
Issue
7
Publish Date
2010
Start Page
702
End Page
702

Mitochondrial Fusion and Autophagy Aid in Removal of Helix-Distorting Mitochondrial DNA Damage

Authors
Bess, AS; Crocker, TL; Meyer, JN
MLA Citation
Bess, AS, Crocker, TL, and Meyer, JN. "Mitochondrial Fusion and Autophagy Aid in Removal of Helix-Distorting Mitochondrial DNA Damage." August 2010.
Source
wos-lite
Published In
Environmental and Molecular Mutagenesis
Volume
51
Issue
7
Publish Date
2010
Start Page
716
End Page
716

Interactome-based analysis of the transcriptomic response to dioxin in developing zebrafish Danio rerio

BACKGROUND: In order to generate hypotheses regarding the mechanisms by which 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) causes toxicity, we analyzed global gene expression changes in developing zebrafish embryos exposed to this potent toxicant in the context of a dynamic gene network. For this purpose, we also computationally inferred a zebrafish (Danio rerio) interactome based on orthologs and interaction data from other eukaryotes. METHODOLOGY/PRINCIPAL FINDINGS: Using novel computational tools to analyze this interactome, we distinguished between dioxin-dependent and dioxin-independent interactions between proteins, and tracked the temporal propagation of dioxin-dependent transcriptional changes from a few genes that were altered initially, to large groups of biologically coherent genes at later times. The most notable processes altered at later developmental stages were calcium and iron metabolism, embryonic morphogenesis including neuronal and retinal development, a variety of mitochondria-related functions, and generalized stress response (not including induction of antioxidant genes). Within the interactome, many of these responses were connected to cytochrome P4501A (cyp1a) as well as other genes that were dioxin-regulated one day after exposure. This suggests that cyp1a may play a key role initiating the toxic dysregulation of those processes, rather than serving simply as a passive marker of dioxin exposure, as suggested by earlier research. CONCLUSIONS/SIGNIFICANCE: Thus, a powerful microarray experiment coupled with a flexible interactome and multi-pronged interactome tools (which are now made publicly available for microarray analysis and related work) suggest the hypothesis that dioxin, best known in fish as a potent cardioteratogen, has many other targets. Many of these types of toxicity have been observed in mammalian species and are potentially caused by alterations to cyp1a.

Authors
Alexeyenko, A; Wassenberg, DM; Lobenhofer, EK; Yen, J; Sonnhammer, ELL; Linney, E; Meyer, JN
MLA Citation
Alexeyenko, A, Wassenberg, DM, Lobenhofer, EK, Yen, J, Sonnhammer, ELL, Linney, E, and Meyer, JN. "Interactome-based analysis of the transcriptomic response to dioxin in developing zebrafish Danio rerio." PLoS ONE 5 (2010): e10465-. (Academic Article)
Source
manual
Published In
PLoS ONE
Volume
5
Publish Date
2010
Start Page
e10465

Caenorhabditis elegans generates biologically relevant levels of genotoxic metabolites from aflatoxin B1 but not benzo[a]pyrene in vivo

There is relatively little information regarding the critical xenobiotic-metabolizing cytochrome P450 (CYP) enzymes in Caenorhabditis elegans, despite this organism's increasing use as a model in toxicology and pharmacology. We carried out experiments to elucidate the capacity of C. elegans to metabolically activate important promutagens via CYPs. Phylogenetic comparisons confirmed an earlier report indicating a lack of CYP1 family enzymes in C. elegans. Exposure to aflatoxin B1 (AFB1), which is metabolized in mammals by CYP1, CYP2, and CYP3 family enzymes, resulted in significant DNA damage in C. elegans. However, exposure to benzo[a]pyrene (BaP), which is metabolized in mammals by CYP1 family enzymes only, produced no detectable damage. To further test whether BaP exposure caused DNA damage, the toxicities of AFB1 and BaP were compared in nucleotide excision repair (NER)-deficient (xpa-1) and NER-proficient (N2) strains of C. elegans. Exposure to AFB1 inhibited growth more in xpa-1 than N2 nematodes, but the growth-inhibitory effects of BaP were indistinguishable in the two strains. Finally, a CYP-nicotinamide adenine dinucleotide phosphate reductase-deficient strain (emb-8) of C. elegans was found to be more resistant to the growth-inhibitory effect of AFB1 exposure than N2, confirming that the AFB1-mediated growth inhibition resulted from CYP-mediated metabolism. Together, these results indicate that C. elegans lacks biologically significant CYP1 family-mediated enzymatic metabolism of xenobiotics. Interestingly, we also found that xpa-1 nematodes were slightly more sensitive to chlorpyrifos than were wild type. Our results highlight the importance of considering differences between xenobiotic metabolism in C. elegans and mammals when using this alternative model in pharmaceutical and toxicological research. © The Author 2010. All rights reserved.

Authors
Leung, MCK; Goldstone, JV; Boyd, WA; Freedman, JH; Meyer, JN
MLA Citation
Leung, MCK, Goldstone, JV, Boyd, WA, Freedman, JH, and Meyer, JN. "Caenorhabditis elegans generates biologically relevant levels of genotoxic metabolites from aflatoxin B1 but not benzo[a]pyrene in vivo." Toxicological Sciences 118.2 (2010): 444-453.
PMID
20864627
Source
scival
Published In
Toxicological Sciences (Elsevier)
Volume
118
Issue
2
Publish Date
2010
Start Page
444
End Page
453
DOI
10.1093/toxsci/kfq295

Apparently normal DNA repair and transcript expression in the RB885 strain carrying an intronic deletion in the xpc-1 gene

Authors
Meyer, JN; Van Houten, B
MLA Citation
Meyer, JN, and Van Houten, B. "Apparently normal DNA repair and transcript expression in the RB885 strain carrying an intronic deletion in the xpc-1 gene." Worm Breeder's Gazette 18 (2010): 23-. (Academic Article)
Source
manual
Published In
Worm Breeder's Gazette
Volume
18
Publish Date
2010
Start Page
23

QPCR: A tool for analysis of mitochondrial and nuclear DNA damage in ecotoxicology

The quantitative PCR (QPCR) assay for DNA damage and repair has been used extensively in laboratory species. More recently, it has been adapted to ecological settings. The purpose of this article is to provide a detailed methodological guide that will facilitate its adaptation to additional species, highlight its potential for ecotoxicological and biomonitoring work, and critically review the strengths and limitations of this assay. Major strengths of the assay include very low (nanogram to picogram) amounts of input DNA; direct comparison of damage and repair in the nuclear and mitochondrial genomes, and different parts of the nuclear genome; detection of a wide range of types of DNA damage; very good reproducibility and quantification; applicability to properly preserved frozen samples; simultaneous monitoring of relative mitochondrial genome copy number; and easy adaptation to most species. Potential limitations include the limit of detection (~1 lesion per 105 bases); the inability to distinguish different types of DNA damage; and the need to base quantification of damage on a control or reference sample. I suggest that the QPCR assay is particularly powerful for some ecotoxicological studies.

Authors
Meyer, JN
MLA Citation
Meyer, JN. "QPCR: A tool for analysis of mitochondrial and nuclear DNA damage in ecotoxicology." Ecotoxicology 19.4 (2010): 804-811.
PMID
20049526
Source
scival
Published In
Ecotoxicology
Volume
19
Issue
4
Publish Date
2010
Start Page
804
End Page
811
DOI
10.1007/s10646-009-0457-4

DNA adducts of decarbamoyl mitomycin C efficiently kill cells without wild-type p53 resulting from proteasome-mediated degradation of checkpoint protein 1

The mitomycin derivative 10-decarbamoyl mitomycin C (DMC) more rapidly activates a p53-independent cell death pathway than mitomycin C (MC). We recently documented that an increased proportion of mitosene1-β-adduct formation occurs in human cells treated with DMC in comparison to those treated with MC. Here, we compare the cellular and molecular response of human cancer cells treated with MC and DMC. We find the increase in mitosene 1-β-adduct formation correlates with a condensed nuclear morphology and increased cytotoxicity in human cancer cells with or without p53. DMC caused more DNA damage than MC in the nuclear and mitochondrial genomes. Checkpoint 1 protein (Chk1) was depleted following DMC, and the depletion of Chk1 by DMC was achieved through the ubiquitin proteasome pathway since chemical inhibition of the proteasome protected against Chk1 depletion. Gene silencing of Chk1 by siRNA increased the cytotoxicity of MC. DMC treatment caused a decrease in the level of total ubiquitinated proteins without increasing proteasome activity, suggesting that DMC mediated DNA adducts facilitate signal transduction to a pathway targeting cellular proteins for proteolysis. Thus, the mitosene-1-β stereoisomeric DNA adducts produced by the DMC signal for a p53-independent mode of cell death correlated with reduced nuclear size, persistent DNA damage, increased ubiquitin proteolysis and reduced Chk1 protein. © 2010 American Chemical Society.

Authors
Boamah, EK; Brekman, A; Tomasz, M; Myeku, N; Figueiredo-Pereira, M; Hunter, S; Meyer, J; Bhosle, RC; Bargonetti, J
MLA Citation
Boamah, EK, Brekman, A, Tomasz, M, Myeku, N, Figueiredo-Pereira, M, Hunter, S, Meyer, J, Bhosle, RC, and Bargonetti, J. "DNA adducts of decarbamoyl mitomycin C efficiently kill cells without wild-type p53 resulting from proteasome-mediated degradation of checkpoint protein 1." Chemical Research in Toxicology 23.7 (2010): 1151-1162.
Website
http://hdl.handle.net/10161/4114
PMID
20536192
Source
scival
Published In
Chemical Research in Toxicology
Volume
23
Issue
7
Publish Date
2010
Start Page
1151
End Page
1162
DOI
10.1021/tx900420k

Nucleotide excision repair genes are expressed at low levels and are not detectably inducible in Caenorhabditis elegans somatic tissues, but their function is required for normal adult life after UVC exposure

We performed experiments to characterize the inducibility of nucleotide excision repair (NER) in Caenorhabditis elegans, and to examine global gene expression in NER-deficient and -proficient strains as well as germline vs. somatic tissues, with and without genotoxic stress. We also carried out experiments to elucidate the importance of NER in the adult life of C. elegans under genotoxin-stressed and control conditions. Adult lifespan was not detectably different between wild-type and NER-deficient xpa-1 nematodes under control conditions. However, exposure to 6 J/m2/day of ultraviolet C radiation (UVC) decreased lifespan in xpa-1 nematodes more than a dose of 100 J/m2/day in wild-type. Similar differential sensitivities were observed for adult size and feeding. Remarkably, global gene expression was nearly identical in young adult wild-type and xpa-1 nematodes, both in control conditions and 3 h after exposure to 50 J/m2 UVC. Neither NER genes nor repair activity were detectably inducible in young adults that lacked germ cells and developing embryos (glp-1 strain). However, expression levels of dozens of NER and other DNA damage response genes were much (5-30-fold) lower in adults lacking germ cells and developing embryos, suggesting that somatic and post-mitotic cells have a much lower DNA repair ability. Finally, we describe a refinement of our DNA damage assay that allows damage measurement in single nematodes. © 2009 Elsevier B.V.

Authors
Boyd, WA; Crocker, TL; Rodriguez, AM; Leung, MCK; Lehmann, DW; Freedman, JH; Houten, BV; Meyer, JN
MLA Citation
Boyd, WA, Crocker, TL, Rodriguez, AM, Leung, MCK, Lehmann, DW, Freedman, JH, Houten, BV, and Meyer, JN. "Nucleotide excision repair genes are expressed at low levels and are not detectably inducible in Caenorhabditis elegans somatic tissues, but their function is required for normal adult life after UVC exposure." Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis 683.1-2 (2010): 57-67.
PMID
19879883
Source
scival
Published In
Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
Volume
683
Issue
1-2
Publish Date
2010
Start Page
57
End Page
67
DOI
10.1016/j.mrfmmm.2009.10.008

Altered gene expression and DNA damage in peripheral blood cells from Friedreich's ataxia patients: Cellular model of pathology

The neurodegenerative disease Friedreich's ataxia (FRDA) is the most common autosomal-recessively inherited ataxia and is caused by a GAA triplet repeat expansion in the first intron of the frataxin gene. In this disease, transcription of frataxin, a mitochondrial protein involved in iron homeostasis, is impaired, resulting in a significant reduction in mRNA and protein levels. Global gene expression analysis was performed in peripheral blood samples from FRDA patients as compared to controls, which suggested altered expression patterns pertaining to genotoxic stress. We then confirmed the presence of genotoxic DNA damage by using a gene-specific quantitative PCR assay and discovered an increase in both mitochondrial and nuclear DNA damage in the blood of these patients (p<0.0001, respectively). Additionally, frataxin mRNA levels correlated with age of onset of disease and displayed unique sets of gene alterations involved in immune response, oxidative phosphorylation, and protein synthesis. Many of the key pathways observed by transcription profiling were downregulated, and we believe these data suggest that patients with prolonged frataxin deficiency undergo a systemic survival response to chronic genotoxic stress and consequent DNA damage detectable in blood. In conclusion, our results yield insight into the nature and progression of FRDA, as well as possible therapeutic approaches. Furthermore, the identification of potential biomarkers, including the DNA damage found in peripheral blood, may have predictive value in future clinical trials.

Authors
Haugen, AC; Prospero, NAD; Parker, JS; Fannin, RD; Chou, J; Meyer, JN; Halweg, C; Collins, JB; Durr, A; Fischbeck, K; Houten, BV
MLA Citation
Haugen, AC, Prospero, NAD, Parker, JS, Fannin, RD, Chou, J, Meyer, JN, Halweg, C, Collins, JB, Durr, A, Fischbeck, K, and Houten, BV. "Altered gene expression and DNA damage in peripheral blood cells from Friedreich's ataxia patients: Cellular model of pathology." PLoS Genetics 6.1 (2010).
Website
http://hdl.handle.net/10161/4460
PMID
20090835
Source
scival
Published In
PLoS genetics
Volume
6
Issue
1
Publish Date
2010
DOI
10.1371/journal.pgen.1000812

Dynamic zebrafish interactome reveals transcriptional mechanisms of dioxin toxicity

Background: In order to generate hypotheses regarding the mechanisms by which 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) causes toxicity, we analyzed global gene expression changes in developing zebrafish embryos exposed to this potent toxicant in the context of a dynamic gene network. For this purpose, we also computationally inferred a zebrafish (Danio rerio) interactome based on orthologs and interaction data from other eukaryotes. Methodology/Principal Findings: Using novel computational tools to analyze this interactome, we distinguished between dioxin-dependent and dioxin-independent interactions between proteins, and tracked the temporal propagation of dioxindependent transcriptional changes from a few genes that were altered initially, to large groups of biologically coherent genes at later times. The most notable processes altered at later developmental stages were calcium and iron metabolism, embryonic morphogenesis including neuronal and retinal development, a variety of mitochondria-related functions, and generalized stress response (not including induction of antioxidant genes). Within the interactome, many of these responses were connected to cytochrome P4501A (cyp1a) as well as other genes that were dioxin-regulated one day after exposure. This suggests that cyp1a may play a key role initiating the toxic dysregulation of those processes, rather than serving simply as a passive marker of dioxin exposure, as suggested by earlier research. Conclusions/Significance: Thus, a powerful microarray experiment coupled with a flexible interactome and multi-pronged interactome tools (which are now made publicly available for microarray analysis and related work) suggest the hypothesis that dioxin, best known in fish as a potent cardioteratogen, has many other targets. Many of these types of toxicity have been observed in mammalian species and are potentially caused by alterations to cyp1a. © 2010 Alexeyenko et al.

Authors
Alexeyenko, A; Wassenberg, DM; Lobenhofer, EK; Yen, J; Linney, E; Sonnhammer, ELL; Meyer, JN
MLA Citation
Alexeyenko, A, Wassenberg, DM, Lobenhofer, EK, Yen, J, Linney, E, Sonnhammer, ELL, and Meyer, JN. "Dynamic zebrafish interactome reveals transcriptional mechanisms of dioxin toxicity." PLoS ONE 5.5 (2010).
PMID
20463971
Source
scival
Published In
PloS one
Volume
5
Issue
5
Publish Date
2010
DOI
10.1371/journal.pone.0010465

Dynamic zebrafish interactome reveals transcriptional mechanisms of dioxin toxicity.

BACKGROUND: In order to generate hypotheses regarding the mechanisms by which 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) causes toxicity, we analyzed global gene expression changes in developing zebrafish embryos exposed to this potent toxicant in the context of a dynamic gene network. For this purpose, we also computationally inferred a zebrafish (Danio rerio) interactome based on orthologs and interaction data from other eukaryotes. METHODOLOGY/PRINCIPAL FINDINGS: Using novel computational tools to analyze this interactome, we distinguished between dioxin-dependent and dioxin-independent interactions between proteins, and tracked the temporal propagation of dioxin-dependent transcriptional changes from a few genes that were altered initially, to large groups of biologically coherent genes at later times. The most notable processes altered at later developmental stages were calcium and iron metabolism, embryonic morphogenesis including neuronal and retinal development, a variety of mitochondria-related functions, and generalized stress response (not including induction of antioxidant genes). Within the interactome, many of these responses were connected to cytochrome P4501A (cyp1a) as well as other genes that were dioxin-regulated one day after exposure. This suggests that cyp1a may play a key role initiating the toxic dysregulation of those processes, rather than serving simply as a passive marker of dioxin exposure, as suggested by earlier research. CONCLUSIONS/SIGNIFICANCE: Thus, a powerful microarray experiment coupled with a flexible interactome and multi-pronged interactome tools (which are now made publicly available for microarray analysis and related work) suggest the hypothesis that dioxin, best known in fish as a potent cardioteratogen, has many other targets. Many of these types of toxicity have been observed in mammalian species and are potentially caused by alterations to cyp1a.

Authors
Alexeyenko, A; Wassenberg, DM; Lobenhofer, EK; Yen, J; Linney, E; Sonnhammer, ELL; Meyer, JN
MLA Citation
Alexeyenko, A, Wassenberg, DM, Lobenhofer, EK, Yen, J, Linney, E, Sonnhammer, ELL, and Meyer, JN. "Dynamic zebrafish interactome reveals transcriptional mechanisms of dioxin toxicity." PloS one 5.5 (2010): e10465-.
Website
http://hdl.handle.net/10161/4537
Source
scival
Published In
PloS one
Volume
5
Issue
5
Publish Date
2010
Start Page
e10465
DOI
10.1371/journal.pone.0010465

The long amplicon quantitative PCR for DNA damage assay as a sensitive method of assessing DNA damage in the environmental model, Atlantic killifish (Fundulus heteroclitus).

DNA damage is an important mechanism of toxicity for a variety of pollutants, and therefore, is often used as an indicator of pollutant effects in ecotoxicological studies. Here, we adapted a PCR-based assay for nuclear and mitochondrial DNA damage for use in an important environmental model, the Atlantic killifish (Fundulus heteroclitus). We refer to this assay as the long amplicon quantitative PCR (LA-QPCR) assay. To validate this method in killifish, DNA damage was measured in liver, brain, and muscle of fish dosed with 10 mg/kg benzo[a]pyrene. This exposure caused 0.4-0.8 lesions/10 kb. We also measured DNA damage in liver and muscle tissues from killifish inhabiting a Superfund site, confirming the utility of this method for biomonitoring. In both cases, damage levels were comparable in nuclear DNA (nDNA) and mitochondrial DNA (mtDNA). Since extensive nDNA sequence data are not readily available for many environmentally relevant species, but mitochondrial genomes are frequently fully sequenced, this assay can be adapted to examine mtDNA damage in virtually any species with little development. Therefore, we argue that this assay will be a valuable tool in assessing DNA damage in ecotoxicological studies.

Authors
Jung, D; Cho, Y; Meyer, JN; Di Giulio, RT
MLA Citation
Jung, D, Cho, Y, Meyer, JN, and Di Giulio, RT. "The long amplicon quantitative PCR for DNA damage assay as a sensitive method of assessing DNA damage in the environmental model, Atlantic killifish (Fundulus heteroclitus)." Comp Biochem Physiol C Toxicol Pharmacol 149.2 (March 2009): 182-186.
PMID
18706522
Source
pubmed
Published In
Comparative Biochemistry and Physiology - Part C: Toxicology & Pharmacology
Volume
149
Issue
2
Publish Date
2009
Start Page
182
End Page
186
DOI
10.1016/j.cbpc.2008.07.007

UV disinfection of adenoviruses: Molecular indications of DNA damage efficiency

Adenovirus is a focus of the water treatment community because of its resistance to standard, monochromatic low-pressure (LP) UV irradiation. Recent research has shown that polychromatic, medium-pressure (MP) UV sources are more effective than LP UV for disinfection of adenovirus when viral inactivation is measured using cell culture infectivity assays; however, UV-induced DNA damage may be repaired during cell culture infectivity assays, and this confounds interpretation of these results. Objectives of this work were to study adenoviral response to both LP and MP UV using (i) standard cell culture infectivity assays and (ii) a PCR assay to directly assess damage to the adenoviral genome without introducing the virus into cell culture. LP and MP UV dose response curves were determined for (i) log inactivation of the virus in cell culture and (ii) UV-induced lesions per kilobase of viral DNA as measured by the PCR assay. Results show that LP and MP UV are equally effective at damaging the genome; MP UV is more effective at inactivating adenovirus in cell culture. This work suggests that the higher disinfection efficacy of MP UV cannot be attributed to a difference in DNA damage induction. These results enhance our understanding of the fundamental mechanisms of UV disinfection of viruses-especially double-stranded DNA viruses that infect humans-and improve the ability of the water treatment community to protect public health. © 2009, American Society for Microbiology. All Rights Reserved.

Authors
Eischeid, AC; Meyer, JN; Linden, KG
MLA Citation
Eischeid, AC, Meyer, JN, and Linden, KG. "UV disinfection of adenoviruses: Molecular indications of DNA damage efficiency." Applied and Environmental Microbiology 75.1 (2009): 23-28.
PMID
18978087
Source
scival
Published In
Applied and environmental microbiology
Volume
75
Issue
1
Publish Date
2009
Start Page
23
End Page
28
DOI
10.1128/AEM.02199-08

Nonadditive effects of PAHs on Early Vertebrate Development: mechanisms and implications for risk assessment.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants. Traditionally, much of the research has focused on the carcinogenic potential of specific PAHs, such as benzo(a)pyrene, but recent studies using sensitive fish models have shown that exposure to PAHs alters normal fish development. Some PAHs can induce a teratogenic phenotype similar to that caused by planar halogenated aromatic hydrocarbons, such as dioxin. Consequently, mechanism of action is often equated between the two classes of compounds. Unlike dioxins, however, the developmental toxicity of PAH mixtures is not necessarily additive. This is likely related to their multiple mechanisms of toxicity and their rapid biotransformation by CYP1 enzymes to metabolites with a wide array of structures and potential toxicities. This has important implications for risk assessment and management as the current approach for complex mixtures of PAHs usually assumes concentration addition. In this review we discuss our current knowledge of teratogenicity caused by single PAH compounds and by mixtures and the importance of these latest findings for adequately assessing risk of PAHs to humans and wildlife. Throughout, we place particular emphasis on research on the early life stages of fish, which has proven to be a sensitive and rapid developmental model to elucidate effects of hydrocarbon mixtures.

Authors
Billiard, SM; Meyer, JN; Wassenberg, DM; Hodson, PV; Di Giulio, RT
MLA Citation
Billiard, SM, Meyer, JN, Wassenberg, DM, Hodson, PV, and Di Giulio, RT. "Nonadditive effects of PAHs on Early Vertebrate Development: mechanisms and implications for risk assessment." Toxicol Sci 105.1 (September 2008): 5-23.
PMID
18156145
Source
pubmed
Published In
Toxicological Sciences (Elsevier)
Volume
105
Issue
1
Publish Date
2008
Start Page
5
End Page
23
DOI
10.1093/toxsci/kfm303

The use of c. elegans to study mitochondrial DNA damage, Fission/Fusion events and autophagy

Authors
Meyer, JN; Arrant, AE; Bernal, AJ; Leung, MC-K; Crocker, TL
MLA Citation
Meyer, JN, Arrant, AE, Bernal, AJ, Leung, MC-K, and Crocker, TL. "The use of c. elegans to study mitochondrial DNA damage, Fission/Fusion events and autophagy." August 2008.
Source
wos-lite
Published In
Environmental and Molecular Mutagenesis
Volume
49
Issue
7
Publish Date
2008
Start Page
522
End Page
522

Effects of polycyclic aromatic hydrocarbons on mitochondrial DNA damage in the killifish (Fundulus heteroclitus)

Authors
Jung, D; Meyer, JN; Di Giulio, RT
MLA Citation
Jung, D, Meyer, JN, and Di Giulio, RT. "Effects of polycyclic aromatic hydrocarbons on mitochondrial DNA damage in the killifish (Fundulus heteroclitus)." MARINE ENVIRONMENTAL RESEARCH 66.1 (July 2008): 32-32.
Source
wos-lite
Published In
Marine Environmental Research
Volume
66
Issue
1
Publish Date
2008
Start Page
32
End Page
32

Caenorhabditis elegans: An emerging model in biomedical and environmental toxicology

The nematode Caenorhabditis elegans has emerged as an important animal model in various fields including neurobiology, developmental biology, and genetics. Characteristics of this animal model that have contributed to its success include its genetic manipulability, invariant and fully described developmental program, well-characterized genome, ease of maintenance, short and prolific life cycle, and small body size. These same features have led to an increasing use of C. elegans in toxicology, both for mechanistic studies and high-throughput screening approaches. We describe some of the research that has been carried out in the areas of neurotoxicology, genetic toxicology, and environmental toxicology, as well as high-throughput experiments with C. elegans including genome-wide screening for molecular targets of toxicity and rapid toxicity assessment for new chemicals. We argue for an increased role for C. elegans in complementing other model systems in toxicological research. © The Author 2008. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved.

Authors
Leung, MCK; Williams, PL; Benedetto, A; Au, C; Helmcke, KJ; Aschner, M; Meyer, JN
MLA Citation
Leung, MCK, Williams, PL, Benedetto, A, Au, C, Helmcke, KJ, Aschner, M, and Meyer, JN. "Caenorhabditis elegans: An emerging model in biomedical and environmental toxicology." Toxicological Sciences 106.1 (2008): 5-28.
PMID
18566021
Source
scival
Published In
Toxicological Sciences (Elsevier)
Volume
106
Issue
1
Publish Date
2008
Start Page
5
End Page
28
DOI
10.1093/toxsci/kfn121

DNA damage assessment in UV-treated adenovirus

Authors
Eischeid, AC; Meyer, JN; Linden, KG
MLA Citation
Eischeid, AC, Meyer, JN, and Linden, KG. "DNA damage assessment in UV-treated adenovirus." Water Quality Technology Conference and Exposition 2008 (2008): 2968-2975.
Source
scival
Published In
Water Quality Technology Conference and Exposition 2008
Publish Date
2008
Start Page
2968
End Page
2975

Fundulus as the premier teleost model in environmental biology: opportunities for new insights using genomics.

A strong foundation of basic and applied research documents that the estuarine fish Fundulus heteroclitus and related species are unique laboratory and field models for understanding how individuals and populations interact with their environment. In this paper we summarize an extensive body of work examining the adaptive responses of Fundulus species to environmental conditions, and describe how this research has contributed importantly to our understanding of physiology, gene regulation, toxicology, and ecological and evolutionary genetics of teleosts and other vertebrates. These explorations have reached a critical juncture at which advancement is hindered by the lack of genomic resources for these species. We suggest that a more complete genomics toolbox for F. heteroclitus and related species will permit researchers to exploit the power of this model organism to rapidly advance our understanding of fundamental biological and pathological mechanisms among vertebrates, as well as ecological strategies and evolutionary processes common to all living organisms.

Authors
Burnett, KG; Bain, LJ; Baldwin, WS; Callard, GV; Cohen, S; Di Giulio, RT; Evans, DH; Gómez-Chiarri, M; Hahn, ME; Hoover, CA; Karchner, SI; Katoh, F; Maclatchy, DL; Marshall, WS; Meyer, JN; Nacci, DE; Oleksiak, MF; Rees, BB; Singer, TD; Stegeman, JJ; Towle, DW; Van Veld, PA; Vogelbein, WK; Whitehead, A; Winn, RN; Crawford, DL
MLA Citation
Burnett, KG, Bain, LJ, Baldwin, WS, Callard, GV, Cohen, S, Di Giulio, RT, Evans, DH, Gómez-Chiarri, M, Hahn, ME, Hoover, CA, Karchner, SI, Katoh, F, Maclatchy, DL, Marshall, WS, Meyer, JN, Nacci, DE, Oleksiak, MF, Rees, BB, Singer, TD, Stegeman, JJ, Towle, DW, Van Veld, PA, Vogelbein, WK, Whitehead, A, Winn, RN, and Crawford, DL. "Fundulus as the premier teleost model in environmental biology: opportunities for new insights using genomics." Comp Biochem Physiol Part D Genomics Proteomics 2.4 (December 2007): 257-286.
PMID
18071578
Source
pubmed
Published In
Comparative Biochemistry and Physiology - Part D: Genomics and Proteomics
Volume
2
Issue
4
Publish Date
2007
Start Page
257
End Page
286
DOI
10.1016/j.cbd.2007.09.001

Phototoxicity in human retinal pigment epithelial cells promoted by hypericin, a component of St. John's wort

St. John's wort (SJW), an over-the-counter antidepressant, contains hypericin, which absorbs light in the UV and visible ranges. In vivo studies have determined that hypericin is phototoxic to skin and our previous in vitro studies with lens tissues have determined that it is potentially phototoxic to the human lens. To determine if hypericin might also be phototoxic to the human retina, we exposed human retinal pigment epithelial (hRPE) cells to 10 -7 to 10-5 M hypericin. Fluorescence emission detected from the cells (λex = 488 nm; λem = 505 nm) confirmed hypericin uptake by human RPE. Neither hypericin exposure alone nor visible light exposure alone reduced cell viability. However when irradiated with 0.7 J cm-2 of visible light (λ > 400 nm) there was loss of cell viability as measured by MTS and lactate dehydrogenase assays. The presence of hypericin in irradiated hRPE cells significantly changed the redox equilibrium of glutathione and a decrease in the activity of glutathione reductase. Increased lipid peroxidation as measured by the thiobarbituric acid reactive substances assay correlated to hypericin concentration in hRPE cells and visible light radiation. Thus, ingested SJW is potentially phototoxic to the retina and could contribute to retinal or early macular degeneration. © 2007 American Society for Photobiology.

Authors
Wielgus, AR; Chignell, CF; Miller, DS; Houten, BV; Meyer, J; Hu, D-N; Roberts, JE
MLA Citation
Wielgus, AR, Chignell, CF, Miller, DS, Houten, BV, Meyer, J, Hu, D-N, and Roberts, JE. "Phototoxicity in human retinal pigment epithelial cells promoted by hypericin, a component of St. John's wort." Photochemistry and Photobiology 83.3 (2007): 706-713.
PMID
17576381
Source
scival
Published In
Photochemistry & Photobiology
Volume
83
Issue
3
Publish Date
2007
Start Page
706
End Page
713
DOI
10.1562/2006-08-09-RA-1001.x

Decline of nucleotide excision repair capacity in aging Caenorhabditis elegans

Background: Caenorhabditis elegans is an important model for the study of DNA damage and repair related processes such as aging, neurodegeneration, and carcinogenesis. However, DNA repair is poorly characterized in this organism. We adapted a quantitative polymerase chain reaction assay to characterize repair of DNA damage induced by ultraviolet type C (UVC) radiation in C. elegans, and then tested whether DNA repair rates were affected by age in adults. Results: UVC radiation induced lesions in young adult C. elegans, with a slope of 0.4 to 0.5 lesions per 10 kilobases of DNA per 100 J/m2, in both nuclear and mitochondrial targets. L1 and dauer larvae were more than fivefold more sensitive to lesion formation than were young adults. Nuclear repair kinetics in a well expressed nuclear gene were biphasic in nongravid adult nematodes: a faster, first order (half-life about 16 hours) phase lasting approximately 24 hours and resulting in removal of about 60% of the photoproducts was followed by a much slower phase. Repair in ten nuclear DNA regions was 15% and 50% higher in more actively transcribed regions in young and aging adults, respectively. Finally, repair was reduced by 30% to 50% in each of the ten nuclear regions in aging adults. However, this decrease in repair could not be explained by a reduction in expression of nucleotide excision repair genes, and we present a plausible mechanism, based on gene expression data, to account for this decrease. Conclusion: Repair of UVC-induced DNA damage in C. elegans is similar kinetically and genetically to repair in humans. Furthermore, this important repair process slows significantly in aging C. elegans, the first whole organism in which this question has been addressed. © 2007 Meyer et al.; licensee BioMed Central Ltd.

Authors
Meyer, JN; Boyd, WA; Azzam, GA; Haugen, AC; Freedman, JH; Houten, BV
MLA Citation
Meyer, JN, Boyd, WA, Azzam, GA, Haugen, AC, Freedman, JH, and Houten, BV. "Decline of nucleotide excision repair capacity in aging Caenorhabditis elegans." Genome Biology 8.5 (2007).
PMID
17472752
Source
scival
Published In
Genome Biology: biology for the post-genomic era
Volume
8
Issue
5
Publish Date
2007
DOI
10.1186/gb-2007-8-5-r70

Mitochondrial toxicity in hearts of CD-1 mice following perinatal exposure to AZT, 3TC, or AZT/3TC in combination

Antiretroviral therapies based on nucleoside reverse transcriptase inhibitors (NRTIs), like zidovudine (3′-azido-3′-deoxythymidine; AZT) and lamivudine ((-)2′,3′-dideoxy-3′-thiacytidine; 3TC), markedly reduce mother-to-child transmission of the human immunodeficiency virus (HIV). However, AZT induces damage in nuclear DNA of mice exposed in utero and postnatally, and mitochondrial DNA (mtDNA) damage has been observed in both human and mouse neonates following perinatal exposure to AZT and AZT/3TC in combination. To provide animal data modeling the NRTI-induced heart damage reported in human infants, we treated pregnant CD-1 mice throughout gestation and treated their pups by direct gavage from postnatal day (PND) 4 through PND 28 with daily doses of 150 mg/kg body weight (bw)/day AZT, 75 mg/kg bw/day 3TC, 125/62.5 mg/kg bw/day AZT/3TC, or the vehicle control. Half the pups were euthanized on PND 28; the remainder received no further dosing, and were euthanized at week 10. Heart tissue was collected, total DNA was extracted, and mtDNA copy number relative to nuclear DNA copy number, mtDNA damage, and mtDNA mutation assays were performed using PCR-based methods. Analyses revealed increases in mtDNA lesions in 4-week-old males and females treated with AZT or 3TC, but not in 10-week-old mice, suggesting that the damage resolved after treatment ceased. Interestingly, 10-week-old females treated with AZT/3TC had significant increases in mtDNA damage. Point mutations were elevated in 10-week-old females treated with AZT or AZT/3TC, but not 3TC; no increases in mutations were seen in either gender at 4 weeks of age. Our data suggest that AZT/3TC combination treatment produces greater mtDNA damage than either agent individually, and that female mice are more sensitive than males to AZT/3TC-induced mtDNA damage.

Authors
Chan, SSL; Santos, JH; Meyer, JN; Mandavilli, BS; Jr, DLC; McCash, CL; Kissling, GE; Nyska, A; Foley, JF; Houten, BV; Copeland, WC; Walker, VE; Witt, KL; Bishop, JB
MLA Citation
Chan, SSL, Santos, JH, Meyer, JN, Mandavilli, BS, Jr, DLC, McCash, CL, Kissling, GE, Nyska, A, Foley, JF, Houten, BV, Copeland, WC, Walker, VE, Witt, KL, and Bishop, JB. "Mitochondrial toxicity in hearts of CD-1 mice following perinatal exposure to AZT, 3TC, or AZT/3TC in combination." Environmental and Molecular Mutagenesis 48.3-4 (2007): 190-200.
PMID
16395692
Source
scival
Published In
Environmental and Molecular Mutagenesis
Volume
48
Issue
3-4
Publish Date
2007
Start Page
190
End Page
200
DOI
10.1002/em.20191

Quantitative PCR-based measurement of nuclear and mitochondrial DNA damage and repair in mammalian cells.

In this chapter, we describe a gene-specific quantitative polymerase chain reaction (QPCR)-based assay for the measurement of DNA damage, using amplification of long DNA targets. This assay has been extensively used to measure the integrity of both nuclear and mitochondrial genomes exposed to different genotoxins, and has proved particularly valuable in identifying reactive oxygen species-mediated mitochondrial DNA (mtDNA) damage. QPCR can be used to quantify the formation of DNA damage, as well as the kinetics of damage removal. One of the main strengths of the assay is that it permits monitoring the integrity of mtDNA directly from total cellular DNA without the need for isolating mitochondria, or a separate step of mtDNA purification. Here we discuss advantages and limitations of using QPCR to assay DNA damage in mammalian cells. In addition, we give a detailed protocol for the QPCR assay that helps facilitate its successful deployment in any molecular biology laboratory.

Authors
Santos, JH; Meyer, JN; Mandavilli, BS; Houten, BV
MLA Citation
Santos, JH, Meyer, JN, Mandavilli, BS, and Houten, BV. "Quantitative PCR-based measurement of nuclear and mitochondrial DNA damage and repair in mammalian cells." Methods in molecular biology (Clifton, N.J.) 314 (2006): 183-199.
PMID
16673882
Source
scival
Published In
Methods in molecular biology (Clifton, N.J.)
Volume
314
Publish Date
2006
Start Page
183
End Page
199

Mitochondrial localization of telomerase as a determinant for hydrogen peroxide-induced mitochondrial DNA damage and apoptosis

We have previously shown that the protein subunit of telomerase, hTERT, has a bonafide N-terminal mitochondrial targeting sequence, and that ectopic hTERT expression in human cells correlated with increase in mtDNA damage after hydrogen peroxide treatment. In this study, we show, using a loxP hTERT construct, that this increase in mtDNA damage following hydrogen peroxide exposure is dependent on the presence of hTERT itself. Further experiments using a dominant negative hTERT mutant shows that telomerase must be catalytically active to mediate the increase in mtDNA damage. Etoposide, but not methylmethanesulfate, also promotes mtDNA lesions in cells expressing active hTERT, indicating genotoxic specificity in this response. Fibroblasts expressing hTERT not only show a ∼2-fold increase in mtDNA damage after oxidative stress but also suffer a 10-30-fold increase in apoptotic cell death as assayed by Annexin-V staining, caspase-3 activation and PARP cleavage. Mutations to the N-terminal mitochondrial leader sequence causes a complete loss of mitochondrial targeting without affecting catalytic activity. Cells carrying this mutated hTERT not only have significantly reduced levels of mtDNA damage following hydrogen peroxide treatment, but strikingly also do not shown any loss of viability or cell growth. Thus, localization of hTERT to the mitochondria renders cells more susceptible to oxidative stress-induced mtDNA damage and subsequent cell death, whereas nuclear-targeted hTERT, in the absence of mitochondrial localization, is associated with diminished mtDNA damage, increased cell survival and protection against cellular senescence. © 2006 Oxford University Press.

Authors
Santos, JH; Meyer, JN; Houten, BV
MLA Citation
Santos, JH, Meyer, JN, and Houten, BV. "Mitochondrial localization of telomerase as a determinant for hydrogen peroxide-induced mitochondrial DNA damage and apoptosis." Human Molecular Genetics 15.11 (2006): 1757-1768.
PMID
16613901
Source
scival
Published In
Human Molecular Genetics
Volume
15
Issue
11
Publish Date
2006
Start Page
1757
End Page
1768
DOI
10.1093/hmg/ddl098

Synergistic developmental toxicity of polycyclic aromatic hydrocarbons: Towards a mechanistic understanding

PAH invariably occur in the environment as complex mixtures of non-substituted PAH, alkyl-PAH, and N-, S-, and O-ring substituted PAH. Recent studies with mixtures derived from pollution events in marine and estuarine systems, e.g., the Exxon Valdez oil spill in Alaska and a wood treatment facility in the Elizabeth River, VA, revealed potent developmental toxicities in fish embryos; most pronounced were cardiovascular defects. These dioxin-mediated effects are associated with the binding of dioxin to the aryl hydrocarbon receptor (AHR), although mechanisms downstream of receptor binding remain unresolved. Other experiments examined interactions between AHR agonists (BaP and β-napthoflavone) and CYP1A inhibitors (α-napthoflavone, piperonyl butoxide, fluoranthene, carbazole and dibenzothiophene); these revealed pronounced synergistic developmental toxicities between AHR agonists and CYP1A inhibitors. This contrasts with the protective effect reported for CYP1A inhibition on the developmental toxicity of dioxins. Current work with zebrafish embryos employing morpholinos to block translation of AHR2 and CYP1A mRNA are consistent with the chemical inducer/inhibitor studies. This observed synergy has important implications for accepted additive models of PAH toxicity, as systems contaminated by PAH contain both AHR agonists and CYP inhibitors. This is an abstract of a paper presented at the symposium on "Pollutant Responses in Marine Organisms" (Alessandria, Italy 6/19-23/2005).

Authors
Giulio, RD; Billiard, S; Meyer, J; Wassenberg, D; Hodson, P
MLA Citation
Giulio, RD, Billiard, S, Meyer, J, Wassenberg, D, and Hodson, P. "Synergistic developmental toxicity of polycyclic aromatic hydrocarbons: Towards a mechanistic understanding." Marine Environmental Research 62.SUPPL. 1 (2006): S45-S46.
Source
scival
Published In
Marine Environmental Research
Volume
62
Issue
SUPPL. 1
Publish Date
2006
Start Page
S45
End Page
S46
DOI
10.1016/j.marenvres.2006.04.037

Analysis of CpG methylation in the killifish CYP1A promoter.

Fundulus heteroclitus (Atlantic killifish or mummichog) inhabiting a creosote-contaminated Superfund site on the Elizabeth River (VA, USA), exhibit a lack of induction of cytochrome P4501A (CYP1A) mRNA, immunodetectable protein, and catalytic activity after exposure to typical inducers. This "refractory CYP1A phenotype" is not explained by alterations in mRNA expression of known CYP1A transcription factors. Furthermore, the refractory phenotype is lost progressively during development in laboratory-reared F1 generation fish. Thus, while heritable, the refractory CYP1A phenotype does not appear to be genetically based. To test the hypothesis that cytosine methylation at CpG sites in the promoter region of CYP1A underlies the refractory CYP1A phenotype, we employed bisulfite sequencing to compare the methylation status of CpG sites in the CYP1A promoter region of DNA from killifish from the Elizabeth River and a reference site. We examined genomic DNA both from livers of wild-caught adult killifish and from pools of F1 generation embryos raised in the laboratory. In fish from both the contaminated and the reference site, cytosine methylation was not detectable at any of the 34 CpG sites examined, including 3 that are part of putative xenobiotic response elements.

Authors
Timme-Laragy, AR; Meyer, JN; Waterland, RA; Di Giulio, RT
MLA Citation
Timme-Laragy, AR, Meyer, JN, Waterland, RA, and Di Giulio, RT. "Analysis of CpG methylation in the killifish CYP1A promoter." Comp Biochem Physiol C Toxicol Pharmacol 141.4 (August 2005): 406-411.
PMID
16257583
Source
pubmed
Published In
Comparative Biochemistry and Physiology - Part C: Toxicology & Pharmacology
Volume
141
Issue
4
Publish Date
2005
Start Page
406
End Page
411
DOI
10.1016/j.cbpc.2005.09.009

Differential display of hepatic mRNA from killifish (Fundulus heteroclitus) inhabiting a Superfund estuary.

Fundulus heteroclitus (Atlantic killifish, mummichog) from a highly contaminated site on the Elizabeth River (VA, USA) are resistant to the toxicity of sediment from the site. However, the mechanistic changes that confer resistance to the toxicity are not yet well understood. We utilized differential display to identify mRNAs that are differentially expressed in hepatic tissue of male and female killifish from the Elizabeth River environment, compared to killifish from a non-contaminated reference site, King's Creek (VA, USA). Seventy-four differentially expressed mRNAs were initially identified (including sex and population-specific differences), and 65 of these were isolated and sequenced. A reverse northern blot array constructed of these cDNAs (plus an additional 15 previously sequenced mRNAs of interest) was used to confirm and quantify expression differences. High interindividual variability was observed in mRNA expression, but multiple differentially expressed mRNAs were identified, including 11 population-specific differences occurring in both sexes, 24 population-specific differences occurring in only one sex, and 22 sex-specific differences. Many of these differentially expressed mRNAs were novel, or not previously hypothesized to play a role in response to contaminant exposure. In addition, the results indicate that the effect of contaminated sediment exposure on the expression of a large proportion of the differentially expressed mRNAs was dependent on the sex of the fish.

Authors
Meyer, JN; Volz, DC; Freedman, JH; Di Giulio, RT
MLA Citation
Meyer, JN, Volz, DC, Freedman, JH, and Di Giulio, RT. "Differential display of hepatic mRNA from killifish (Fundulus heteroclitus) inhabiting a Superfund estuary." Aquat Toxicol 73.4 (July 30, 2005): 327-341.
PMID
15916819
Source
pubmed
Published In
Aquatic Toxicology
Volume
73
Issue
4
Publish Date
2005
Start Page
327
End Page
341
DOI
10.1016/j.aquatox.2005.03.022

Mitochondrial hTERT exacerbates free-radical-mediated mtDNA damage

Telomerase is often re-activated in human cancers and is widely used to immortalize cells in culture. In addition to the maintenance of telomeres, telomerase has been implicated in cell proliferation, genomic instability and apoptosis. Here we show that human telomerase reverse transcriptase (hTERT) is targeted to the mitochondria by an N-terminal leader sequence, and that mitochondrial extracts contain telomerase activity. In seven different human cell lines, mitochondrial telomerase increases hydrogen-peroxide-mediated mitochondrial DNA damage. hTERT expression did not alter the rate of hydrogen peroxide breakdown or endogenous cellular levels. Because the damaging effects of hydrogen peroxide are mediated by divalent metal ions (Fenton chemistry), we examined the levels of bioavailable metals. In all cases, higher levels of chelatable metals were found in hTERT-expressing cells. These results suggest that mitochondrial telomerase sensitizes cells to oxidative stress, which can lead to apoptotic cell death, and imply a novel function of telomerase in mitochondrial DNA transactions. © Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland 2004.

Authors
Santos, JH; Meyer, JN; Skorvaga, M; Annab, LA; Houten, BV
MLA Citation
Santos, JH, Meyer, JN, Skorvaga, M, Annab, LA, and Houten, BV. "Mitochondrial hTERT exacerbates free-radical-mediated mtDNA damage." Aging Cell 3.6 (2004): 399-411.
PMID
15569357
Source
scival
Published In
Aging Cell
Volume
3
Issue
6
Publish Date
2004
Start Page
399
End Page
411
DOI
10.1111/j.1474-9728.2004.00124.x

A caenorhabditis elegans model of Friedreich's ataxia shows iron sensitivity, mitochondrial DNA damage, and altered gene expression.

Authors
Meyer, JN; Boyd, WA; Haugen, AC; Freedman, JH; Van Houten, B
MLA Citation
Meyer, JN, Boyd, WA, Haugen, AC, Freedman, JH, and Van Houten, B. "A caenorhabditis elegans model of Friedreich's ataxia shows iron sensitivity, mitochondrial DNA damage, and altered gene expression." 2004.
Source
wos-lite
Published In
Environmental and Molecular Mutagenesis
Volume
44
Issue
3
Publish Date
2004
Start Page
215
End Page
215

Antioxidant defenses in killifish (Fundulus heteroclitus) exposed to contaminated sediments and model prooxidants: short-term and heritable responses.

A population of killifish (Fundulus heteroclitus) inhabiting a Superfund site on the Elizabeth River (VA, USA) is tolerant of the acute toxicity of the sediments from the site; previous work suggests that this tolerance is based both on genetic adaptation and physiological acclimation. In this study, larval first- and second-generation (F1 and F2) offspring of Elizabeth River killifish were more resistant to the toxicity of t-butyl hydroperoxide (a model prooxidant) than were King's Creek (reference site) offspring, indicating a heritable tolerance of exposure to oxidative stress. In laboratory experiments designed to elucidate the mechanistic basis for this increased tolerance, we exposed laboratory-raised F1 and F2 offspring from Elizabeth River and King's Creek killifish to Elizabeth River sediments, menadione, or t-butyl hydroperoxide, and measured the following antioxidant parameters: total oxyradical scavenging capacity (TOSC); glutathione content (total and disulfide); activities of glutathione reductase (GR); glutathione peroxidase (GPx); and glutamate cysteine ligase (GCL) activities and protein levels of copper-zinc superoxide dismutase (CuZnSOD); and protein levels of manganese superoxide dismutase (MnSOD). Exposure to Elizabeth River sediments lead to consistent increases in total glutathione concentrations, GR activities, and MnSOD protein levels, and in some cases increased GPx and GCL activities, in both populations. In addition, Elizabeth River offspring (larvae) showed higher basal TOSC values, glutathione concentrations, and MnSOD protein levels. These data suggest that upregulated antioxidant defenses play a role in both short-term (physiological) and heritable (multigenerational/evolutionary) tolerance of the toxicity of these Superfund sediments. The responses of specific antioxidant parameters, including sex-specific responses in the cases of glutathione concentrations and GR activity, are also discussed.

Authors
Meyer, JN; Smith, JD; Winston, GW; Di Giulio, RT
MLA Citation
Meyer, JN, Smith, JD, Winston, GW, and Di Giulio, RT. "Antioxidant defenses in killifish (Fundulus heteroclitus) exposed to contaminated sediments and model prooxidants: short-term and heritable responses." Aquat Toxicol 65.4 (December 10, 2003): 377-395.
PMID
14568353
Source
pubmed
Published In
Aquatic Toxicology
Volume
65
Issue
4
Publish Date
2003
Start Page
377
End Page
395

Expression and inducibility of aryl hydrocarbon receptor pathway genes in wild-caught killifish (Fundulus heteroclitus) with different contaminant-exposure histories.

Wildcaught killifish from a contaminated site on the Elizabeth River (VA, USA) are refractory to induction of cytochrome P4501A (CYP1A, measured as catalytic activity and immunodetectable CYP1A protein) after exposure to typical aryl hydrocarbon receptor (AHR) agonists, as has been reported for fish from other sites highly contaminated with these compounds. In an attempt to understand the molecular basis for the lack of inducibility of CYP1A protein expression and activity in Elizabeth River killifish, we analyzed the expression of CYP1A and four other members of the AHR signal transduction pathway: AHR1, AHR2, AHR repressor (AHRR), and AHR nuclear translocator (ARNT). Gene expression was measured by cycle-optimized reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of messenger ribonucleic acid (mRNA) extracted from livers of killifish from the Elizabeth River and King's Creek (VA, USA) (reference site), 36 h after injection with beta-naphthoflavone (BNF, an AHR agonist) or corn oil (carrier control). Hepatic CYP1A mRNA was inducible in King's Creek killifish. However, in Elizabeth River killifish, no induction of CYP1A mRNA was observed, confirming and extending previous results showing no induction of CYP1A protein or catalytic activity in this population. Similarly, AHRR and AHR2 mRNA levels were induced by BNF in King's Creek but not Elizabeth River killifish. No population or treatment-related differences were observed in expression of AHR1 or ARNT mRNAs. The results reveal in Elizabeth River killifish a consistent lack of inducibility of genes that are normally inducible by AHR agonists (CYP1A, AHRR, AHR2). However, the expression of AHR1, AHR2, and AHRR in vehicle-treated fish did not differ between Elizabeth River and King's Creek killifish, suggesting that altered constitutive expression of AHRs or AHRR does not underlie the refractory CYP1A phenotype in Elizabeth River killifish.

Authors
Meyer, JN; Wassenberg, DM; Karchner, SI; Hahn, ME; Di Giulio, RT
MLA Citation
Meyer, JN, Wassenberg, DM, Karchner, SI, Hahn, ME, and Di Giulio, RT. "Expression and inducibility of aryl hydrocarbon receptor pathway genes in wild-caught killifish (Fundulus heteroclitus) with different contaminant-exposure histories." Environ Toxicol Chem 22.10 (October 2003): 2337-2343.
PMID
14551997
Source
pubmed
Published In
Environmental Toxicology & Chemistry
Volume
22
Issue
10
Publish Date
2003
Start Page
2337
End Page
2343

Heritable adaptation and fitness costs in killifish (Fundulus heteroclitus) inhabiting a polluted estuary

Adaptation to contaminants in the environment has been studied extensively in microbes, insects, and plants, and increasing evidence suggests that certain vertebrate populations as well are evolving in response to pollution. Here, we show that F1 and F2 laboratory-raised offspring of killifish (Fundulus heteroclitus, also known as mummichog) from a highly contaminated site on the Elizabeth River (Virginia, USA) are more resistant to the toxicity of Elizabeth River sediments than are offspring of reference site killifish. This resistance is more marked in the F1 than in the F2 generation, but it remains significant in the F2 generation, indicating that the resistant phenotype in the feral Elizabeth River killifish is based on both genetic and nongenetic mechanisms. In addition, both the F1 and F2 generation offspring of the Elizabeth River killifish are more susceptible to other stressors, both anthropogenic (photoenhanced toxicity) and natural (hypoxia), suggesting that the changes that have conferred resistance to the toxicity of the Elizabeth River sediments carry a cost of reduced fitness in other contexts.

Authors
Meyer, JN; Giulio, RTD
MLA Citation
Meyer, JN, and Giulio, RTD. "Heritable adaptation and fitness costs in killifish (Fundulus heteroclitus) inhabiting a polluted estuary." Ecological Applications 13.2 (2003): 490-503.
Source
scival
Published In
Ecological Applications
Volume
13
Issue
2
Publish Date
2003
Start Page
490
End Page
503

Patterns of heritability of decreased EROD activity and resistance to PCB 126-induced teratogenesis in laboratory-reared offspring of killifish (Fundulus heteroclitus) from a creosote-contaminated site in the Elizabeth River, VA, USA.

Killifish (Fundulus heteroclitus) from a highly contaminated site on the Elizabeth River are resistant to the acute toxicity and the cytochrome P4501A (CYP1A)-inducing activity of both the sediments from the site and chemically pure polycyclic aromatic hydrocarbons (PAHs). These effects are highly heritable for one generation, but heritable to a lesser degree by subsequent generations, in clean conditions in the laboratory. We show that offspring of this population of Elizabeth River killifish are also resistant to the teratogenicity and P4501A-inducing activity of PCB congener 126, a prototypical coplanar halogenated aromatic hydrocarbon (HAH). Furthermore, the pattern of greater resistance to acute toxicity and P4501A-inducing activity in the first generation and less in subsequent generations is also observed upon exposure to PCB-126.

Authors
Meyer, J; Di Giulio, R
MLA Citation
Meyer, J, and Di Giulio, R. "Patterns of heritability of decreased EROD activity and resistance to PCB 126-induced teratogenesis in laboratory-reared offspring of killifish (Fundulus heteroclitus) from a creosote-contaminated site in the Elizabeth River, VA, USA." Mar Environ Res 54.3-5 (September 2002): 621-626.
PMID
12408627
Source
pubmed
Published In
Marine Environmental Research
Volume
54
Issue
3-5
Publish Date
2002
Start Page
621
End Page
626

Cytochrome P4501A (CYP1A) in killifish (Fundulus heteroclitus): heritability of altered expression and relationship to survival in contaminated sediments.

Previous research has shown that killifish (Fundulus heteroclitus) inhabiting a creosote-contaminated site on the Elizabeth River in Virginia exhibit little induction of cytochrome P4501A (CYP1A) protein expression and activity upon exposure to typical CYP1A-inducing chemicals. We characterized the CYP1A response of first, second, and third generation laboratory-raised offspring of feral Elizabeth River killifish to exposure to sediments from the contaminated site as well as the prototypical polycyclic aromatic hydrocarbon (PAH)-type CYP1A inducers beta-naphthoflavone (BNF) and 3-methylcholanthrene (3-MC). The Elizabeth River offspring's responses were compared to those of offspring of killifish from two reference sites (King's Creek, Virginia, and Russell Creek, North Carolina). As with feral Elizabeth River killifish, the first generation embryos and larvae were refractory to CYP1A induction. However, the response observed in 3-year-old first generation adults, as well as with second and third generation fish, was much closer to that observed in reference-site fish. We suggest that the pattern of altered CYP1A response in Elizabeth River killifish, while persistent and heritable for one generation, is mostly nongenetically based. Additionally, we investigated the hypothesis that low CYP1A activity (measured as in ovo EROD activity) would correlate to increased survival in Elizabeth River sediment pore water; this hypothesis was not supported by our results.

Authors
Meyer, JN; Nacci, DE; Di Giulio, RT
MLA Citation
Meyer, JN, Nacci, DE, and Di Giulio, RT. "Cytochrome P4501A (CYP1A) in killifish (Fundulus heteroclitus): heritability of altered expression and relationship to survival in contaminated sediments." Toxicol Sci 68.1 (July 2002): 69-81.
PMID
12075112
Source
pubmed
Published In
Toxicological Sciences (Elsevier)
Volume
68
Issue
1
Publish Date
2002
Start Page
69
End Page
81

Increased sensitivity to oxidative stress in a creosote-adapted population of mummichog (Fundulus heteroclitus)

With increasing frequency, aquatic organisms inhabit regions where biochemical adaptations to contaminants are essential for survival. The resultant selection for individuals better adapted to a polluted environment may result in a population better able to survive certain stressors, but less fit in terms of other stressors. Research with F1 offspring of the mummichog Fundulus heteroclitus collected from a highly creosote-contaminated site on the Elizabeth River has explored the nature of the resistance demonstrated by this population, as well as some of the costs associated with it. F1 larvae and juveniles from the Elizabeth River were more able to survive exposure to contaminated sediments from the Elizabeth River, either in the presence or absence of UV light, than were F1 offspring of control site (York River) Fundulus. On the other hand, the Elizabeth River F1 population was more susceptible to phototoxicity as mediated by pure anthracene or fluoranthene, indicating a possible cost of adaptation. Furthermore, preliminary studies suggest that Elizabeth River Fundulus are more sensitive to another source of oxidative stress, H2O2. Ongoing studies are exploring the biochemical and genetic bases of these differences. Copyright (C) 2000 Elsevier Science Ltd.

Authors
Meyer, JN; MacLean, ED; Giulio, RTD
MLA Citation
Meyer, JN, MacLean, ED, and Giulio, RTD. "Increased sensitivity to oxidative stress in a creosote-adapted population of mummichog (Fundulus heteroclitus)." Marine Environmental Research 50.1-5 (2000): 78--.
Source
scival
Published In
Marine Environmental Research
Volume
50
Issue
1-5
Publish Date
2000
Start Page
78-

Assessment of immunotoxicology in wild populations: Review and recommendations

A heightened recognition of the immunotoxicity of many xenobiotics has sparked increased interest in studying immune system effects in wildlife. Immunotoxicological endpoints have been directly informative in assessing the health of wildlife populations themselves, and wildlife could also potentially be used as indicators of human and ecosystem health. However, the lack of standard methods and information regarding normal ranges of immune system parameters makes field assessments of wildlife immunological status difficult. Compounding this difficulty is the unfamiliarity of most wildlife toxicologists with the complex immune system and the wide array of methods available to study immunotoxicity. This restricts the number of studies carried out and further limits the growth of a wildlife immunological database. The purpose of this review is to facilitate the study of immunological endpoints by wildlife toxicologists by presenting 1) an overview of immunotoxicology from a biomedical perspective with an emphasis on the fundamentals of the immune system and the tools/assays available for measuring its function; 2) a limited review of applied immunotoxicity studies in wild fish, birds, and mammals; and 3) recommendations for expanding immunological assessments in wildlife.

Authors
Keller, JM; Meyer, JN; Mattie, M; Augspurger, T; Rau, M; Dong, J; Levin, ED
MLA Citation
Keller, JM, Meyer, JN, Mattie, M, Augspurger, T, Rau, M, Dong, J, and Levin, ED. "Assessment of immunotoxicology in wild populations: Review and recommendations." Reviews in Toxicology 3.1-4 (1999): 167-212.
Source
scival
Published In
Reviews in Toxicology
Volume
3
Issue
1-4
Publish Date
1999
Start Page
167
End Page
212
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Research Areas:

  • Abnormalities, Drug-Induced
  • Aldehydes
  • Benzopyrans
  • Calcium
  • Calibration
  • Cell Survival
  • DNA Replication
  • Dose-Response Relationship, Drug
  • Energy Metabolism
  • Fluorenes
  • Genotype
  • Half-Life
  • HeLa Cells
  • Heart
  • Heart Defects, Congenital
  • Humic Substances
  • Laboratories
  • Larva
  • Molecular Structure
  • Mutation
  • Neoplasm Proteins
  • Phosphorylation
  • Ponds
  • Proteolysis
  • Silver Nitrate
  • Solubility
  • Structure-Activity Relationship
  • Sulfides
  • Toxicity Tests
  • Transcriptome