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Rasal KD, Mohapatra S, Kumar PV, K SR, Asgolkar P, Acharya A, Dey D, Shinde S, Vasam M, Kumar R, Sundaray JK. DNA Methylation Profiling of Ovarian Tissue of Climbing Perch (Anabas testudienus) in Response to Monocrotophos Exposure. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2023; 25:1123-1135. [PMID: 37870741 DOI: 10.1007/s10126-023-10264-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/17/2023] [Indexed: 10/24/2023]
Abstract
Epigenetic modifications like DNA methylation can alter an organism's phenotype without changing its DNA sequence. Exposure to environmental toxicants has the potential to change the resilience of aquatic species. However, little information is available on the dynamics of DNA methylation in fish gonadal tissues in response to organophosphates. In the present work, reduced-representation bisulfite sequencing was performed to identify DNA methylation patterns in the ovarian tissues of Anabas testudienus exposed to organophosphates, specifically monocrotophos (MCP). Through sequencing, an average of 41,087 methylated cytosine sites were identified and distributed in different parts of genes, i.e., in transcription start sites (TSS), promoters, exons, etc. A total of 1058 and 1329 differentially methylated regions (DMRs) were detected as hyper-methylated and hypo-methylated in ovarian tissues, respectively. Utilizing whole-genome data of the climbing perch, the DMRs, and their associated overlapping genes revealed a total of 22 genes within exons, 45 genes at transcription start sites (TSS), and 218 genes in intergenic regions. Through gene ontology analysis, a total of 16 GO terms particularly involved in ovarian follicular development, response to oxidative stress, oocyte maturation, and multicellular organismal response to stress associated with reproductive biology were identified. After functional enrichment analysis, relevant DMGs such as steroid hormone biosynthesis (Cyp19a, 11-beta-HSD, 17-beta-HSD), hormone receptors (ar, esrrga), steroid metabolism (StAR), progesterone-mediated oocyte maturation (igf1ar, pgr), associated with ovarian development in climbing perch showed significant differential methylation patterns. The differentially methylated genes (DMGs) were subjected to analysis using real-time PCR, which demonstrated altered gene expression levels. This study revealed a molecular-level alteration in genes associated with ovarian development in response to chemical exposure. This work provides evidence for understanding the relationship between DNA methylation and gene regulation in response to chemicals that affect the reproductive fitness of aquatic animals.
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Affiliation(s)
- Kiran D Rasal
- ICAR-Central Institute of Freshwater Aquaculture, Bhubaneswar, 751 002, Odisha, India
- ICAR-Central Institute of Fisheries Education, Mumbai, 400 061, Maharashtra, India
| | - Sujata Mohapatra
- ICAR-Central Institute of Freshwater Aquaculture, Bhubaneswar, 751 002, Odisha, India
| | - Pokanti Vinay Kumar
- ICAR-Central Institute of Fisheries Education, Mumbai, 400 061, Maharashtra, India
| | - Shasti Risha K
- ICAR-Central Institute of Fisheries Education, Mumbai, 400 061, Maharashtra, India
| | - Prachi Asgolkar
- ICAR-Central Institute of Fisheries Education, Mumbai, 400 061, Maharashtra, India
| | - Arpit Acharya
- ICAR-Central Institute of Fisheries Education, Mumbai, 400 061, Maharashtra, India
| | - Diganta Dey
- ICAR-Central Institute of Fisheries Education, Mumbai, 400 061, Maharashtra, India
| | - Siba Shinde
- ICAR-Central Institute of Fisheries Education, Mumbai, 400 061, Maharashtra, India
| | - Manohar Vasam
- ICAR-Central Institute of Freshwater Aquaculture, Bhubaneswar, 751 002, Odisha, India
| | - Rajesh Kumar
- ICAR-Central Institute of Freshwater Aquaculture, Bhubaneswar, 751 002, Odisha, India
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Cediel-Ulloa A, Lindner S, Rüegg J, Broberg K. Epigenetics of methylmercury. Neurotoxicology 2023; 97:34-46. [PMID: 37164037 DOI: 10.1016/j.neuro.2023.05.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 05/03/2023] [Accepted: 05/05/2023] [Indexed: 05/12/2023]
Abstract
PURPOSE OF REVIEW Methylmercury (MeHg) is neurotoxic at high levels and particularly affects the developing brain. One proposed mechanism of MeHg neurotoxicity is alteration of the epigenetic programming. In this review, we summarise the experimental and epidemiological literature on MeHg-associated epigenetic changes. RECENT FINDINGS Experimental and epidemiological studies have identified changes in DNA methylation following in utero exposure to MeHg, and some of the changes appear to be persistent. A few studies have evaluated associations between MeHg-related changes in DNA methylation and neurodevelopmental outcomes. Experimental studies reveal changes in histone modifications after MeHg exposure, but we lack epidemiological studies supporting such changes in humans. Experimental and epidemiological studies have identified microRNA-related changes associated with MeHg; however, more research is needed to conclude if these changes lead to persistent and toxic effects. SUMMARY MeHg appears to interfere with epigenetic processes, potentially leading to persistent changes. However, observed associations of mercury with epigenetic changes are as of yet of unknown relevance to neurodevelopmental outcomes.
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Affiliation(s)
- Andrea Cediel-Ulloa
- Department of Organism Biology, Uppsala University, Kåbovägen 4, 752 36 Uppsala, Sweden
| | - Sabrina Lindner
- Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Joëlle Rüegg
- Department of Organism Biology, Uppsala University, Kåbovägen 4, 752 36 Uppsala, Sweden
| | - Karin Broberg
- Division of Occupational and Environmental Medicine, Department of Laboratory Medicine, Lund University, Lund, Sweden; Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
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Tian S, Sun W, Sun X, Yue Y, Jia M, Huang S, Zhou Z, Li L, Diao J, Yan S, Zhu W. Intergenerational reproductive toxicity of parental exposure to prothioconazole and its metabolite on offspring and epigenetic regulation associated with DNA methylation in zebrafish. ENVIRONMENT INTERNATIONAL 2023; 173:107830. [PMID: 36805811 DOI: 10.1016/j.envint.2023.107830] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/22/2023] [Accepted: 02/13/2023] [Indexed: 06/18/2023]
Abstract
Prothioconazole (PTC) is a widely used agricultural fungicide, and its parent and metabolite prothioconazole-desthio (dPTC) have been detected in diverse environmental media. This study was aimed at investigating the gender-dependent effects on adult zebrafish reproduction and intergenerational effects on offspring development following parental exposure to PTC and dPTC. The results showed that after the adult zebrafish (F0) was exposed to 0.5 and 10 μg/L PTC and dPTC for 21 days, the fertility and gametogenesis of female zebrafish were decreased more significantly than that of male zebrafish. After that, three fecundity tests were conducted in the exposure period to explore the development endpoints of F1 embryos/larvae without further treatment with PTC and dPTC exposure. However, PTC and dPTC exposure did lead to abnormal development of F1 embryos, including delayed hatching, shortened body length, abnormal development and significant changes in locomotor behavior. These changes were related to the abnormal expression of sex hormones and the regulation of DNA methylation in F0 fish. In a word, the results of this study showed that parental PTC and dPTC interference have sex-dependent reproductive toxicity on F0 zebrafish, which may be passed on to the next generation through epigenetic modification involving DNA methylation, resulting in alternations in growth phenotype of offspring.
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Affiliation(s)
- Sinuo Tian
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Wei Sun
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Xiaoxuan Sun
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Yifan Yue
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Ming Jia
- Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Shiran Huang
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Zhiqiang Zhou
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Li Li
- College of Plant Protection, Shanxi Agricultural University, Taiyuan 030031, China
| | - Jinling Diao
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China
| | - Sen Yan
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China; Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China.
| | - Wentao Zhu
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing 100193, China.
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Ke T, Tinkov AA, Skalny AV, Santamaria A, Rocha JBT, Bowman AB, Chen W, Aschner M. Epigenetics and Methylmercury-Induced Neurotoxicity, Evidence from Experimental Studies. TOXICS 2023; 11:toxics11010072. [PMID: 36668798 PMCID: PMC9860901 DOI: 10.3390/toxics11010072] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/08/2023] [Accepted: 01/10/2023] [Indexed: 05/14/2023]
Abstract
MeHg is an environmental neurotoxin that can adversely affect the development of the nervous system. The molecular integrity of chromatin in the nucleus is an important target of MeHg. Low levels of MeHg trigger epigenetic mechanisms that may be involved in long-lasting and transgenerational neurotoxicity after exposure. Emerging evidence has shown that these mechanisms include histone modification, siRNA, and DNA methylation. The MeHg-induced inhibition of neurodifferentiation and neurogenesis are mechanistically associated with epigenetic alterations in critical genes, such as neurotrophin brain-derived neurotrophic factor (BDNF). Further, MeHg exposure has been shown to alter the activity and/or expression of the upstream regulators of chromatin structure, including histone deacetylases (HDACs) and DNA methyltransferase (DNMTs), which may trigger permanent alterations in histone modifications and DNA methylation. MeHg-exposure also alters several species of miRNA that are associated with neurodevelopment. Genetic studies in the C. elegans model of MeHg-induced toxicity proposes a potential interplay between exogenous RNAi and antioxidant defense. In this review, we discuss the molecular basis for MeHg exposure-induced alterations in chromatin structure and the roles of histone modifications, siRNA, and DNA methylation in MeHg-induced neurotoxic effects.
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Affiliation(s)
- Tao Ke
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Correspondence: (T.K.); (M.A.)
| | - Alexey A. Tinkov
- World-Class Research Center “Digital Biodesign and Personalized Healthcare”, IM Sechenov First Moscow State Medical University (Sechenov University), 119435 Moscow, Russia
- Laboratory of Ecobiomonitoring and Quality Control, Yaroslavl State University, 150003 Yaroslavl, Russia
- Department of Medical Elementology, RUDN University, 117198 Moscow, Russia
| | - Anatoly V. Skalny
- World-Class Research Center “Digital Biodesign and Personalized Healthcare”, IM Sechenov First Moscow State Medical University (Sechenov University), 119435 Moscow, Russia
- Department of Medical Elementology, RUDN University, 117198 Moscow, Russia
| | - Abel Santamaria
- Laboratorio de Aminoácidos Excitadores/Laboratorio de Neurofarmacología Molecular y Nanotecnología, Instituto Nacional de Neurología y Neurocirugía, Mexico City 14269, Mexico
| | - Joao B. T. Rocha
- Departamento de Bioquímica e Biologia Molecular, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria 97105-900, RS, Brazil
| | - Aaron B. Bowman
- School of Health Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Wen Chen
- Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Correspondence: (T.K.); (M.A.)
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Lu K, Liang XF, Liu T, Cai W, Zhuang W, Zhang Y, Bibi A. DNA methylation of pck1 might contribute to the programming effects of early high-carbohydrate diets feeding to the glucose metabolism across two generations in zebrafish (Danio rerio). FISH PHYSIOLOGY AND BIOCHEMISTRY 2022; 48:1619-1633. [PMID: 36481836 DOI: 10.1007/s10695-022-01149-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 11/19/2022] [Indexed: 06/17/2023]
Abstract
The purpose of this study is to assess the effects of early high-carbohydrate stimulus on glucose metabolism in zebrafish (Danio rerio) over two generations and explore the mechanisms that explain those nutritional programming effects via epigenetic modifications. The larvae were delivered a high-carbohydrate diet (53.66%) that was used as an early nutritional stimulus from the first feeding to the end of the yolk sac (FF) and 5 days after yolk-sac exhaustion (YE). The larvae (F0) and their offspring (F1) were then both fed the control diet (22.69%) until adulthood (15 weeks), and they were challenged with a high-carbohydrate diet (35.36%) at the 16th week. The results indicated that early stimulus immediately raised the mRNA levels of genes involved in glycolysis and gluconeogenesis. At the end of F0 challenge, both treatment groups decreased the plasma glucose levels, increased the expression levels of glucokinase (gck), and inhibited the mRNA during gluconeogenesis. When challenged in F1, the glucose levels were lower in FF (F1), and the mRNA levels of phosphoenolpyruvate carboxykinase 1 (pck1) were decreased in FF (F1) and YE (F1). Besides, in both experimental groups (F0 and F1), the CpG island of pck1 maintained lower levels of hypermethylated expression from F0 adult, 24 h post-fertilization embryo, to F1 adult. In conclusion, these results indicated that an early high-carbohydrate stimulus could significantly reprogram glucose metabolism in adult zebrafish, that those modifications could be partially transmitted to the next generation, and that the DNA methylation of pck1 might work as a stable epigenetic marker to contribute to those processes.
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Affiliation(s)
- Ke Lu
- College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No.1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China
- Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, 430070, China
| | - Xu-Fang Liang
- College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No.1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China.
- Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, 430070, China.
| | - Tong Liu
- College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No.1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China
- Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, 430070, China
| | - Wenjing Cai
- College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No.1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China
- Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, 430070, China
| | - Wuyuan Zhuang
- College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No.1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China
- Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, 430070, China
| | - Yanpeng Zhang
- College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No.1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China
- Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, 430070, China
| | - Asima Bibi
- College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, No.1, Shizishan Street, Hongshan District, Wuhan, 430070, Hubei Province, China
- Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan, 430070, China
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Pan J, Li X, Liu H, Wang C, Xu S, Xu B, Deng Y, Yang T, Liu W. Exploring the molecular mechanisms underlie the endoplasmic reticulum stress-mediated methylmercury-induced neuronal developmental damage. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 245:114099. [PMID: 36152427 DOI: 10.1016/j.ecoenv.2022.114099] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 09/01/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Methylmercury (MeHg) is a ubiquitous environmental pollutant, which can cross the placenta and blood brain barrier, thus affecting fetal growth and development. Although previous studies have demonstrated that MeHg induces endoplasmic reticulum (ER) stress in rat cerebral cortex and primary neurons, the role of ER stress in MeHg-induced neurodevelopmental toxicity remains unclear. Here, we used ICR pregnant mice and hippocampal neurons cells (HT22 cells) to investigate the molecular mechanism by which MeHg exposure during pregnancy affects neurodevelopment. We found that prenatal MeHg exposure caused developmental delay in offspring, accompanied with ER stress, cell apoptosis, cell cycle arrest and abnormal DNA methylation. Then, we used ER stress specific inhibitor 4-PBA and CHOP siRNA to investigate the role of ER stress on HT22 cells damage caused by MeHg. The results showed that 4-PBA pretreatment restored MeHg-induced axonal shortening and alleviated apoptosis, cell cycle arrest and DNA methylation. At the same time, the activation of CHOP/c-Jun/GADD45A signaling pathway was inhibited, and the interaction between CHOP and c-Jun was weakened. In addition, CHOP siRNA reduced the expression of c-Jun and GADD45A, and relieved DNA methylation levels to some extent. In summary, our study suggested that ER stress induced by MeHg mediated cell apoptosis and cell cycle arrest, and may affect DNA methylation through activation of CHOP/c-Jun/GADD45A signaling pathway, thus leading to neuronal damage.
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Affiliation(s)
- Jingjing Pan
- Department of Environmental Health, School of Public Health, China Medical University, China
| | - Xiaoyang Li
- Department of Environmental Health, School of Public Health, China Medical University, China
| | - Haihui Liu
- Department of Environmental Health, School of Public Health, China Medical University, China
| | - Chen Wang
- Department of Environmental Health, School of Public Health, China Medical University, China
| | - Si Xu
- Department of Environmental Health, School of Public Health, China Medical University, China
| | - Bin Xu
- Department of Environmental Health, School of Public Health, China Medical University, China
| | - Yu Deng
- Department of Environmental Health, School of Public Health, China Medical University, China
| | - Tianyao Yang
- Department of Environmental Health, School of Public Health, China Medical University, China
| | - Wei Liu
- Department of Environmental Health, School of Public Health, China Medical University, China.
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Terrazas-Salgado L, García-Gasca A, Betancourt-Lozano M, Llera-Herrera R, Alvarado-Cruz I, Yáñez-Rivera B. Epigenetic Transgenerational Modifications Induced by Xenobiotic Exposure in Zebrafish. Front Cell Dev Biol 2022; 10:832982. [PMID: 35281093 PMCID: PMC8914061 DOI: 10.3389/fcell.2022.832982] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 01/21/2022] [Indexed: 11/23/2022] Open
Abstract
Zebrafish (Danio rerio) is a well-established vertebrate model in ecotoxicology research that responds to a wide range of xenobiotics such as pesticides, drugs, and endocrine-disrupting compounds. The epigenome can interact with the environment and transform internal and/or external signals into phenotypic responses through changes in gene transcription. Environmental exposures can also generate epigenetic variations in offspring even by indirect exposure. In this review, we address the advantages of using zebrafish as an experimental animal model to study transgenerational epigenetic processes upon exposure to xenobiotics. We focused mostly on DNA methylation, although studies on post-translational modifications of histones, and non-coding RNAs related to xenobiotic exposure in zebrafish are also discussed. A revision of the methods used to study epigenetic changes in zebrafish revealed the relevance and reproducibility for epigenetics-related research. PubMed and Google Scholar databases were consulted for original research articles published from 2013 to date, by using six keywords: zebrafish, epigenetics, exposure, parental, transgenerational, and F2. From 499 articles identified, 92 were considered, of which 14 were selected as included F2 and epigenetic mechanisms. Current knowledge regarding the effect of xenobiotics on DNA methylation, histone modifications, and changes in non-coding RNAs expressed in F2 is summarized, along with key experimental design considerations to characterize transgenerational effects.
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Affiliation(s)
| | | | | | - Raúl Llera-Herrera
- Instituto de Ciencias del Mar y Limnología—Unidad Académica Mazatlán, Universidad Nacional Autónoma de México, Mazatlán, Mexico
| | - Isabel Alvarado-Cruz
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, Tucson, AZ, United States
| | - Beatriz Yáñez-Rivera
- Centro de Investigación en Alimentación y Desarrollo, A. C., Mazatlán, Mexico
- Consejo Nacional de Ciencia y Tecnología, México, Mexico
- *Correspondence: Beatriz Yáñez-Rivera,
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Pan J, Li X, Wei Y, Ni L, Xu B, Deng Y, Yang T, Liu W. Advances on the Influence of Methylmercury Exposure during Neurodevelopment. Chem Res Toxicol 2022; 35:43-58. [PMID: 34989572 DOI: 10.1021/acs.chemrestox.1c00255] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Mercury (Hg) is a toxic heavy-metal element, which can be enriched in fauna and flora and transformed into methylmercury (MeHg). MeHg is a widely distributed environmental pollutant that may be harmful to fish-eating populations through enrichment of aquatic food chains. The central nervous system is a primary target of MeHg. Embryos and infants are more sensitive to MeHg, and exposure to MeHg during gestational feeding can significantly impair the homeostasis of offspring, leading to long-term neurodevelopmental defects. At present, MeHg-induced neurodevelopmental toxicity has become a hotspot in the field of neurotoxicology, but its mechanisms are not fully understood. Some evidence point to oxidative damage, excitotoxicity, calcium ion imbalance, mitochondrial dysfunction, epigenetic changes, and other molecular mechanisms that play important roles in MeHg-induced neurodevelopmental toxicity. In this review, advances in the study of neurodevelopmental toxicity of MeHg exposure during pregnancy and the molecular mechanisms of related pathways are summarized, in order to provide more scientific basis for the study of neurodevelopmental toxicity of MeHg.
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Affiliation(s)
- Jingjing Pan
- Department of Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenbei New District, Shenyang 110122, Liaoning China
| | - Xiaoyang Li
- Department of Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenbei New District, Shenyang 110122, Liaoning China
| | - Yanfeng Wei
- Department of Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenbei New District, Shenyang 110122, Liaoning China
| | - Linlin Ni
- Department of Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenbei New District, Shenyang 110122, Liaoning China
| | - Bin Xu
- Department of Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenbei New District, Shenyang 110122, Liaoning China
| | - Yu Deng
- Department of Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenbei New District, Shenyang 110122, Liaoning China
| | - Tianyao Yang
- Department of Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenbei New District, Shenyang 110122, Liaoning China
| | - Wei Liu
- Department of Environmental Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenbei New District, Shenyang 110122, Liaoning China
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Guo CY, Tseng PW, Hwang JS, Wu GC, Chang CF. Potential role of DNA methylation of cyp19a1a promoter during sex change in protogynous orange-spotted grouper, Epinephelus coioides. Gen Comp Endocrinol 2021; 311:113840. [PMID: 34216589 DOI: 10.1016/j.ygcen.2021.113840] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 06/24/2021] [Accepted: 06/26/2021] [Indexed: 11/26/2022]
Abstract
Estrogen has a pivotal role in early female differentiation and further ovarian development. Aromatase (Cyp19a) is responsible for the conversion of androgens to estrogens in vertebrates. In teleosts, cyp19a1a and it paralog cyp19a1b are mainly expressed in the ovary and hypothalamus, respectively. Decreased plasma estrogen levels and lower cyp19a1a expression are associated with the initiation of female-to-male sex change in protogynous grouper. However, an 17α-methyltestosterone (MT)-induced the sex change from a female to a precocious male is a transient phase, and a reversible sex change (induced male-to-female) occurs after chemical withdrawal. Thus, we used this characteristic to study the epigenetic modification of cyp19a1a promoter in orange-spotted grouper. CpG-rich region with a CpG island is located on the putative regulatory region of distal cyp19a1a promoter. Our results showed that cyp19a1a promoter exhibited tissue-specific methylation status. Low methylation levels of distal cyp19a1a promoter and hypomethylated (0-40%) clones of cyp19a1a promoter region were widely observed in the ovary but not shown in testis and other tissues. In femaleness, higher numbers of hypomethylated clones of cyp19a1a promoter region were observed in the vitellogenic oocyte stage compared to the primary oocyte stage. Furthermore, decreased numbers of hypomethylated clones of cyp19a1a promoter region were associated with the maleness during the female-to-male sex change. DNA methylation inhibitor (5-aza-2'-deoxycytidine) delayed the spermatogenesis process (according to germ cell stage and numbers: by decrease of sperm and increase of spermatocytes) but did not influence the reversed sex change in MT-induced bi-directional sex change. These results suggest that epigenetic modification of cyp19a1a promoter may play an important role during the sex change in orange-spotted grouper.
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Affiliation(s)
- Chun-Yang Guo
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan; Institute of Marine Biology, National Taiwan Ocean University, Keelung, Taiwan
| | - Peng-Wei Tseng
- Doctoral Degree Program in Marine Biotechnology, National Taiwan Ocean University, Keelung, Taiwan; Doctoral Degree Program in Marine Biotechnology, Academia Sinica, Taipei, Taiwan
| | - Jiang-Shiou Hwang
- Institute of Marine Biology, National Taiwan Ocean University, Keelung, Taiwan; Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan
| | - Guan-Chung Wu
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan; Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan.
| | - Ching-Fong Chang
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan; Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan.
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Kim S, Thapar I, Brooks BW. Epigenetic changes by per- and polyfluoroalkyl substances (PFAS). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 279:116929. [PMID: 33751946 DOI: 10.1016/j.envpol.2021.116929] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/07/2021] [Accepted: 03/03/2021] [Indexed: 05/09/2023]
Abstract
Increasing studies are examining per- and polyfluoroalkyl substances (PFAS) induced toxicity and resulting health outcomes, including epigenetic modifications (e.g., DNA methylation, histone modification, microRNA expression). We critically reviewed current evidence from human epidemiological, in vitro, and animal studies, including mammalian and aquatic model organisms. Epidemiological studies identified the associations between perfluorooctane sulfonate (PFOS) or perfluorooctanoic acid (PFOA) exposure and epigenetic changes in both adult populations and birth cohorts. For in vitro studies, various cell types including neuroblasts, preadipocytes, and hepatocytes have been employed to understand epigenetic effects of PFAS. In studies with animal models, effects of early life exposure to PFAS have been examined using rodent models, and aquatic models (e.g., zebrafish) have been more frequently used in recent years. Several studies highlighted oxidative stress as a key mediator between epigenetic modification and health effects. Collectively, previous research clearly suggest involvement of epigenetic mechanisms in PFAS induced toxicity, though these efforts have primarily focused on specific PFASs (i.e. mainly PFOS and PFOA) or endpoints (i.e. cancer). Additional studies are necessary to define specific linkages among epigenetic mechanisms and related biomarkers or phenotypical changes. In addition, future research is also needed for understudied PFAS and complex mixtures. Studies of epigenetic effects elicited by individual PFAS and mixtures are needed within an adverse outcome pathways framework, which will advance an understanding of PFAS risks to public health and the environment, and support efforts to design less hazardous chemicals.
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Affiliation(s)
- Sujin Kim
- Department of Environmental Science, Baylor University, Waco, TX, 76706, USA; Institute of Biomedical Studies, Baylor University, Waco, TX, 76706, USA.
| | - Isha Thapar
- Department of Environmental Science, Baylor University, Waco, TX, 76706, USA; Honors College, Baylor University, Waco, TX, 76706, USA
| | - Bryan W Brooks
- Department of Environmental Science, Baylor University, Waco, TX, 76706, USA; Institute of Biomedical Studies, Baylor University, Waco, TX, 76706, USA.
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11
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Ding X, Sun W, Dai L, Liu C, Sun Q, Wang J, Zhang P, Li K, Yu L. Parental exposure to environmental concentrations of tris(1,3-dichloro-2-propyl)phosphate induces abnormal DNA methylation and behavioral changes in F1 zebrafish larvae. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 267:115305. [PMID: 32841905 DOI: 10.1016/j.envpol.2020.115305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 07/05/2020] [Accepted: 07/19/2020] [Indexed: 06/11/2023]
Abstract
Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) has been demonstrated to be transferred from parental animals to their offspring. However, whether parental exposure to environmental concentrations of TDCIPP show neurodevelopmental toxicity in the F1 generation and the possible underlying mechanism remain unclear. Therefore, in this study, zebrafish embryos were exposed to environmental concentrations of TDCIPP (3, 30 and 300 ng L-1) for 120 days. The effects of exposure on motor behaviors, neurotransmitter levels, DNA methylation, and gene expression of F1 larvae were investigated. Parental exposure left TDCIPP residues in F1 eggs as well as reduced body length of F1 larvae. Moreover, parental exposure significantly reduced swimming activity in F1 5 dpf larvae, although it did not significantly alter serotonin, dopamine, 3,4-dihydroxyphenylacetic acid, γ-aminobutyrate, and acetylcholine levels. Genes encoding DNA methylation transferases (dnmt3aa and dnmt1) were downregulated in F1 larvae. Reduced representation bisulfite sequencing analysis revealed 446 differentially methylated regions and enriched neuronal cell body Gene Ontology term in F1 generation. Correlation analysis between the expression of genes related to neural cell body and swimming speed indicated that solute carrier family 1 member 2b (slc1a2b) downregulation might be responsible for the inhibition of motor behaviors. Furthermore, bisulfite amplicon sequencing analysis confirmed hypermethylation of the promoter region of slc1a2b in F1 larvae following parental exposure to 300 ng L-1 TDCIPP, which might have led to significant downregulation of gene expression and, in turn, influenced the motor behaviors. These results indicate that parental exposure to environmental concentrations of TDCIPP alters DNA methylation, downregulates gene expressions and, thus inducing developmental neurotoxicity, in F1 larvae.
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Affiliation(s)
- Xisheng Ding
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wen Sun
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China
| | - Lili Dai
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, China
| | - Chunsheng Liu
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Provincial Engineering Laboratory for Pond Aquaculture, China
| | - Qian Sun
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Provincial Engineering Laboratory for Pond Aquaculture, China
| | - Jianghua Wang
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Provincial Engineering Laboratory for Pond Aquaculture, China
| | - Panwei Zhang
- China Institute of Water Resources and Hydropower Research, Beijing, 100038, China
| | - Kun Li
- China Institute of Water Resources and Hydropower Research, Beijing, 100038, China
| | - Liqin Yu
- College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Hubei Provincial Engineering Laboratory for Pond Aquaculture, China.
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12
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Shankar P, Dasgupta S, Hahn ME, Tanguay RL. A Review of the Functional Roles of the Zebrafish Aryl Hydrocarbon Receptors. Toxicol Sci 2020; 178:215-238. [PMID: 32976604 PMCID: PMC7706399 DOI: 10.1093/toxsci/kfaa143] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Over the last 2 decades, the zebrafish (Danio rerio) has emerged as a stellar model for unraveling molecular signaling events mediated by the aryl hydrocarbon receptor (AHR), an important ligand-activated receptor found in all eumetazoan animals. Zebrafish have 3 AHRs-AHR1a, AHR1b, and AHR2, and studies have demonstrated the diversity of both the endogenous and toxicological functions of the zebrafish AHRs. In this contemporary review, we first highlight the evolution of the zebrafish ahr genes, and the characteristics of the receptors including developmental and adult expression, their endogenous and inducible roles, and the predicted ligands from homology modeling studies. We then review the toxicity of a broad spectrum of AHR ligands across multiple life stages (early stage, and adult), discuss their transcriptomic and epigenetic mechanisms of action, and report on any known interactions between the AHRs and other signaling pathways. Through this article, we summarize the promising research that furthers our understanding of the complex AHR pathway through the extensive use of zebrafish as a model, coupled with a large array of molecular techniques. As much of the research has focused on the functions of AHR2 during development and the mechanism of TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) toxicity, we illustrate the need to address the considerable knowledge gap in our understanding of both the mechanistic roles of AHR1a and AHR1b, and the diverse modes of toxicity of the various AHR ligands.
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Affiliation(s)
- Prarthana Shankar
- Department of Environmental and Molecular Toxicology, The Sinnhuber Aquatic Research Laboratory, Oregon State University, Corvallis, Oregon 97331
| | - Subham Dasgupta
- Department of Environmental and Molecular Toxicology, The Sinnhuber Aquatic Research Laboratory, Oregon State University, Corvallis, Oregon 97331
| | - Mark E Hahn
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
| | - Robyn L Tanguay
- Department of Environmental and Molecular Toxicology, The Sinnhuber Aquatic Research Laboratory, Oregon State University, Corvallis, Oregon 97331
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13
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Bicho RC, Scott-Fordsmand JJ, Amorim MJB. Developing an epigenetics model species - From blastula to mature adult, life cycle methylation profile of Enchytraeus crypticus (Oligochaete). THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 732:139079. [PMID: 32428769 DOI: 10.1016/j.scitotenv.2020.139079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/07/2020] [Accepted: 04/26/2020] [Indexed: 06/11/2023]
Abstract
DNA methylation is an epigenetic mechanism of particular importance in developmental biology, but methylation also varies along organisms' life cycle. Recent studies have deliberated copper (Cu) exposure induced epigenetic changes in Enchytraeus crypticus, a standard species belonging to one of the most common and important genera of soil invertebrates in many ecosystems. There is however no information on how DNA methylation levels change within the life cycle of this species. We here investigate the global DNA methylation profile along the life cycle of E. crypticus and compare this to the expression of target genes involved in methylation. Results showed that after the lowest DNA methylation level at day 3 (early embryonic stage, blastula) there was an increase by day 7 (organogenesis) after which levels were maintained at days 11, 18 and 25. DNA methyltransferase associated protein 1 (DMPA1) and Methyl Binding Domain 2 (MBD2) gene expression was highest during embryo stages (3 to 7 days), then decreasing (11, 18 days) and finally unregulated in adults (25 days). Hence, we here show that DNA methylation in E. crypticus changes among the different life stages, from cocoons to adults. Such information is a key knowledge to use this endpoint and tool in an ecotoxicology context. This means that it is almost implicit that gene expression levels are age specific for a given stressor. It seems logic to recommend to always compare individuals with the same age between treatments, and to be careful when extrapolating results among life stages. Once, we understand more of these effects we may even be able to predict which life stage is more sensitive to specific stressors. An experimental design that aims to cover epigenetics of stressors in a multigenerational exposure, including transgenerational effects, should ensure the synchronous age of organisms for sampling analysis purposes.
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Affiliation(s)
- Rita C Bicho
- Department of Biology & CESAM, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Janeck J Scott-Fordsmand
- Department of Bioscience, Aarhus University, Vejlsovej 25, PO Box 314, DK-8600 Silkeborg, Denmark
| | - Mónica J B Amorim
- Department of Biology & CESAM, University of Aveiro, 3810-193 Aveiro, Portugal.
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14
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Jones ER, Simning D, Serafin J, Sepúlveda MS, Griffitt RJ. Acute exposure to oil induces age and species-specific transcriptional responses in embryo-larval estuarine fish. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 263:114325. [PMID: 32240905 DOI: 10.1016/j.envpol.2020.114325] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 02/04/2020] [Accepted: 03/02/2020] [Indexed: 06/11/2023]
Abstract
Because oil spills frequently occur in coastal regions that serve as spawning habitat, characterizing the effects of oil in estuarine fish carries both economic and environmental importance. There is a breadth of research investigating the effects of crude oil on fish, however few studies have addressed how transcriptional responses to oil change throughout development or how these responses might be conserved across taxa. To investigate these effects, we performed RNA-seq and pathway analysis following oil exposure 1) in a single estuarine species (Cyprinodon variegatus) at three developmental time points (embryos, yolk-sack larvae, free-feeding larvae), and 2) in two ecologically similar species (C. variegatus and Fundulus grandis), immediately post-hatch (yolk-sack stage). Our results indicate that C. variegatus embryos mount a diminished transcriptional response to oil compared to later stages, and that few transcriptional responses are conserved throughout development. Pathway analysis of larval C. variegatus revealed dysregulation of similar biological processes at later larval stages, including alteration of cholesterol biosynthesis pathways, cardiac development processes, and immune functions. Our cross-species comparison showed that F. grandis exhibited a reduced transcriptional response compared to C. variegatus. Pathway analysis revealed that the two species shared similar immune and cardiac responses, however pathways related to cholesterol biosynthesis exhibited a divergent response as they were activated in C. variegatus but inhibited in F. grandis. Our results suggest that examination of larval stages may provide a more sensitive estimate of oil-impacts than examination of embryos, and challenge assumptions that ecologically comparable species respond to oil similarly.
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Affiliation(s)
- Elizabeth R Jones
- Division of Coastal Sciences, School of Ocean Science and Engineering, The University of Southern Mississippi, United States; Department of Biology, Francis Marion University, United States.
| | - Danielle Simning
- Division of Coastal Sciences, School of Ocean Science and Engineering, The University of Southern Mississippi, United States
| | - Jenifer Serafin
- Department of Forestry and Natural Resources, Purdue University, United States
| | - Maria S Sepúlveda
- Department of Forestry and Natural Resources, Purdue University, United States
| | - Robert J Griffitt
- Division of Coastal Sciences, School of Ocean Science and Engineering, The University of Southern Mississippi, United States
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15
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Bicho RC, Roelofs D, Mariën J, Scott-Fordsmand JJ, Amorim MJB. Epigenetic effects of (nano)materials in environmental species - Cu case study in Enchytraeus crypticus. ENVIRONMENT INTERNATIONAL 2020; 136:105447. [PMID: 31924578 DOI: 10.1016/j.envint.2019.105447] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/17/2019] [Accepted: 12/24/2019] [Indexed: 06/10/2023]
Abstract
Chemical stressors can induce epigenomic changes, i.e., changes that are transferred to the next generation, even when the stressor is removed. Literature on chemical induced epigenetic effects in environmental species is scarce. We here provide the first results on epigenetic effects caused by nanomaterials with an environmental OECD standard soil model species Enchytraeus crypticus species. We assessed the epigenetic potential in terms of global DNA methylation, gene-specific methylation via bisulfite sequencing and MS-HRM (Methylation Sensitive - High Resolution Melting), and gene expression qPCR for genes involved in DNA methylation, histone modifications, non-coding RNA and stress response mechanisms). We have exposed E. crypticus in a multigenerational (MG) test design to Cu (copper oxide nanomaterials (CuO NMs) and copper salt (CuCl2)). To link possible epigenetic effects to population changes, we used exposure concentrations (ECx) that caused a 10% and 50% reduction in the reproductive output (10% and 50% are the standards for regulatory Risk Assessment), the organisms were exposed for five consecutive generations (F1-F5) plus two generations after transferring to clean media (F5-F7), 7 generations in a total of 224 days. Results showed that MG exposure to Cu increased global DNA methylation and corresponded with phenotypic effects (reproduction). Gene expression analyses showed changes in the epigenetic, stress and detoxification gene targets, depending on the generation and Cu form, also occurring in post-exposure generations, hence indicative of transgenerational effects. There were in general clear differences between organisms exposed to different Cu-forms, hence indicate nanoparticulate-specific effects.
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Affiliation(s)
- Rita C Bicho
- Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Dick Roelofs
- Department of Ecological Science, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, the Netherlands
| | - Janine Mariën
- Department of Ecological Science, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, the Netherlands
| | - Janeck J Scott-Fordsmand
- Department of Bioscience, Aarhus University, Vejlsovej 25, PO BOX 314, DK-8600 Silkeborg, Denmark
| | - Mónica J B Amorim
- Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
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16
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Methylmercury Epigenetics. TOXICS 2019; 7:toxics7040056. [PMID: 31717489 PMCID: PMC6958348 DOI: 10.3390/toxics7040056] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 10/22/2019] [Accepted: 11/05/2019] [Indexed: 12/12/2022]
Abstract
Methylmercury (MeHg) has conventionally been investigated for effects on nervous system development. As such, epigenetic modifications have become an attractive mechanistic target, and research on MeHg and epigenetics has rapidly expanded in the past decade. Although, these inquiries are a recent advance in the field, much has been learned in regards to MeHg-induced epigenetic modifications, particularly in the brain. In vitro and in vivo controlled exposure studies illustrate that MeHg effects microRNA (miRNA) expression, histone modifications, and DNA methylation both globally and at individual genes. Moreover, some effects are transgenerationally inherited, as organisms not directly exposed to MeHg exhibited biological and behavioral alterations. miRNA expression generally appears to be downregulated consequent to exposure. Further, global histone acetylation also seems to be reduced, persist at distinct gene promoters, and is contemporaneous with enhanced histone methylation. Moreover, global DNA methylation appears to decrease in brain-derived tissues, but not in the liver; however, selected individual genes in the brain are hypermethylated. Human epidemiological studies have also identified hypo- or hypermethylated individual genes, which correlated with MeHg exposure in distinct populations. Intriguingly, several observed epigenetic modifications can be correlated with known mechanisms of MeHg toxicity. Despite this knowledge, however, the functional consequences of these modifications are not entirely evident. Additional research will be necessary to fully comprehend MeHg-induced epigenetic modifications and the impact on the toxic response.
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17
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Kelsey KT, Rytel M, Dere E, Butler R, Eliot M, Huse SM, Houseman EA, Koestler DC, Boekelheide K. Serum dioxin and DNA methylation in the sperm of operation ranch hand veterans exposed to Agent Orange. Environ Health 2019; 18:91. [PMID: 31665024 PMCID: PMC6819394 DOI: 10.1186/s12940-019-0533-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/01/2019] [Indexed: 05/09/2023]
Abstract
BACKGROUND Exposure to the herbicide Agent Orange during the Vietnam War was widespread and is associated with numerous adverse health outcomes. A continuing concern of veterans is the possibility that exposure to the dioxin-containing herbicide might induce adverse reproductive outcomes. We sought to assess whether exposure to Agent Orange in Vietnam was associated with changes in DNA methylation in sperm in a subset of Vietnam veterans who participated in the Air Force Health Study (AFHS). METHODS We studied 37 members of the AFHS chosen to have no, low, medium or high exposure to Agent Orange, based upon serum dioxin levels obtained during a series of examinations. DNA from stored semen was extracted and DNA methylation assessed on the Illumina 450 K platform. RESULTS Initial epigenome-wide analysis returned no loci that survived control for false discovery. However, the TEAD3 gene had four different CpG sites that showed loss of DNA methylation associated with dioxin exposure. Analysis assessing regional DNA methylation changes revealed 36 gene regions, including the region of the imprinted gene H19 to have altered DNA methylation associated with high exposure compared to the low exposure group. Additional comparison of our data with sperm DNA methylation data from Russian boys exposed to dioxin found an additional 5 loci that were altered in both studies and exhibited a consistent direction of association. CONCLUSIONS Studying a small number of sperm samples from veterans enrolled in the AFHS, we did not find evidence of significant epigenome-wide alterations associated with exposure to Agent Orange. However, additional analysis showed that the H19 gene region is altered in the sperm of Agent Orange-exposed Ranch Hand veterans. Our study also replicated several findings of a prior study of dioxin-exposed Russian boys. These results provide additional candidate loci for further investigation and may have implications for the reproductive health of dioxin-exposed individuals.
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Affiliation(s)
- Karl T. Kelsey
- Department of Epidemiology, Brown University School of Public Health, Providence, RI 02912 USA
- Department of Pathology and Laboratory Medicine, Brown University School of Public Health, Providence, RI 02912 USA
| | - Matthew Rytel
- Department of Epidemiology, Brown University School of Public Health, Providence, RI 02912 USA
| | - Edward Dere
- Department of Pathology and Laboratory Medicine, Brown University School of Public Health, Providence, RI 02912 USA
| | - Rondi Butler
- Department of Epidemiology, Brown University School of Public Health, Providence, RI 02912 USA
- Department of Pathology and Laboratory Medicine, Brown University School of Public Health, Providence, RI 02912 USA
| | - Melissa Eliot
- Department of Epidemiology, Brown University School of Public Health, Providence, RI 02912 USA
| | - Susan M. Huse
- NIAID Collaborative Bioinformatics Resource, Frederick National Laboratory for Cancer Research, Frederick, MD 21701 USA
| | | | - Devin C. Koestler
- Department of Biostatistics & Data Science, University of Kansas Medical Center, Kansas City, KS 66160 USA
| | - Kim Boekelheide
- Department of Pathology and Laboratory Medicine, Brown University School of Public Health, Providence, RI 02912 USA
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18
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Viluksela M, Pohjanvirta R. Multigenerational and Transgenerational Effects of Dioxins. Int J Mol Sci 2019; 20:E2947. [PMID: 31212893 PMCID: PMC6627869 DOI: 10.3390/ijms20122947] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 12/12/2022] Open
Abstract
Dioxins are ubiquitous and persistent environmental contaminants whose background levels are still reason for concern. There is mounting evidence from both epidemiological and experimental studies that paternal exposure to the most potent congener of dioxins, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), can lower the male/female ratio of offspring. Moreover, in laboratory rodents and zebrafish, TCDD exposure of parent animals has been reported to result in reduced reproductive performance along with other adverse effects in subsequent generations, foremost through the paternal but also via the maternal germline. These impacts have been accompanied by epigenetic alterations in placenta and/or sperm cells, including changes in methylation patterns of imprinted genes. Here, we review recent key studies in this field with an attempt to provide an up-to-date picture of the present state of knowledge to the reader. These studies provide biological plausibility for the potential of dioxin exposure at a critical time-window to induce epigenetic alterations across multiple generations and the significance of aryl hydrocarbon receptor (AHR) in mediating these effects. Currently available data do not allow to accurately estimate the human health implications of these findings, although epidemiological evidence on lowered male/female ratio suggests that this effect may take place at realistic human exposure levels.
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Affiliation(s)
- Matti Viluksela
- School of Pharmacy and Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland.
- Environmental Health Unit, National Institute for Health and Welfare, P.O. Box 95, FI-70701 Kuopio, Finland.
| | - Raimo Pohjanvirta
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, FI-00014 Helsinki, Finland.
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19
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Abstract
The laboratory zebrafish (Danio rerio) is now an accepted model in toxicologic research. The zebrafish model fills a niche between in vitro models and mammalian biomedical models. The developmental characteristics of the small fish are strategically being used by scientists to study topics ranging from high-throughput toxicity screens to toxicity in multi- and transgenerational studies. High-throughput technology has increased the utility of zebrafish embryonic toxicity assays in screening of chemicals and drugs for toxicity or effect. Additionally, advances in behavioral characterization and experimental methodology allow for observation of recognizable phenotypic changes after xenobiotic exposure. Future directions in zebrafish research are predicted to take advantage of CRISPR-Cas9 genome editing methods in creating models of disease and interrogating mechanisms of action with fluorescent reporters or tagged proteins. Zebrafish can also model developmental origins of health and disease and multi- and transgenerational toxicity. The zebrafish has many advantages as a toxicologic model and new methodologies and areas of study continue to expand the usefulness and application of the zebrafish.
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Affiliation(s)
| | - Jennifer L Freeman
- School of Health Sciences, Purdue University, West Lafayette, Indiana 47907
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20
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Olsvik PA, Whatmore P, Penglase SJ, Skjærven KH, Anglès d'Auriac M, Ellingsen S. Associations Between Behavioral Effects of Bisphenol A and DNA Methylation in Zebrafish Embryos. Front Genet 2019; 10:184. [PMID: 30906313 PMCID: PMC6418038 DOI: 10.3389/fgene.2019.00184] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 02/19/2019] [Indexed: 12/21/2022] Open
Abstract
Endocrine-disrupting contaminants have been associated with aberrant changes in epigenetic pathways in animals. In this study, zebrafish embryos were exposed bisphenol A (BPA) to search for associations between behavior and epigenetic mechanisms in fish. For concentration-dependent responses, embryos were exposed to a range of BPA concentrations (0.1 nM to 30 μM). Embryos were analyzed for locomotor activity at 3-, 4-, and 5-days post fertilization (dpf) in response to changing light conditions. Based on concentration-dependent effects on behavior and gene expression, 10 μM BPA [from 24 to 96 hours post fertilization (hpf)] was used for a whole-genome bisulfite sequencing (WGBS) study searching for genome-wide impacts on DNA methylation. Over the examined concentration ranges, hyperactivity was demonstrated for exposures to 0.001 μM BPA in comparison to embryos exposed to lower or higher BPA concentrations. Transcriptional analysis showed significant effects at >0.01 μM BPA for two genes related to DNA methylation (dnmt1, cbs). BPA exposure did not significantly affect global DNA methylation, but 20,474 differentially methylated (DM) sites in 4,873 genes were identified by WGBS analysis. Most DM sites were identified within gene bodies. The genes with the most DM sites were all protocadherin 2 gamma subfamily genes, related to axon targeting, synaptic development and neuronal survival. KEGG pathways most significantly affected by BPA exposure were phosphatidylinositol signaling system, followed by VEGF and MAPK signaling pathways. This study shows that BPA can affect zebrafish embryo swimming activity at very low concentrations as well as affecting numerous methylated sites in genes which are overrepresented in functionally relevant metabolic pathways. In conclusion, altered methylation patterns of genes associated with nervous system development might lead to abnormal swimming activity.
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21
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Akemann C, Meyer DN, Gurdziel K, Baker TR. Developmental Dioxin Exposure Alters the Methylome of Adult Male Zebrafish Gonads. Front Genet 2019; 9:719. [PMID: 30687390 PMCID: PMC6336703 DOI: 10.3389/fgene.2018.00719] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 12/21/2018] [Indexed: 01/20/2023] Open
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental toxicant and endocrine disrupting compound with reproductive and developmental effects in humans and model organisms, including zebrafish. Our previous microarray and histological studies found defects in spermatogenesis and fertility of zebrafish in response to acute developmental TCDD exposure. These effects are apparent following exposure during reproductive development, modeling fetal basis of adult-onset disease. Some outcomes of these previous studies (reduced fertility, changes in sex ratio, transcriptomic alterations) are also transgenerational – persisting to unexposed generations – through the male germline. We hypothesized that DNA methylation could be a possible mechanism for these reproductive effects and performed whole genome bisulfite sequencing (WGBS), which identifies whole genome DNA methylation status at the base pair level, on testes of adult zebrafish exposed to TCDD (two separate hour-long exposures to 50 pg/mL TCDD at 3 and 7 weeks post fertilization). In response to TCDD exposure, multiple genes were differentially methylated; many of which are involved in reproductive processes or epigenetic modifications, suggesting a role of DNA methylation in later-life health outcomes. Additionally, several differentially methylated genes corresponded with gene expression changes identified in TCDD-exposed zebrafish testes, indicating a potential link between DNA methylation and gene expression. Ingenuity pathway analysis of WGBS and microarray data revealed genes involved in reproductive processes and development, RNA regulation, the cell cycle, and cellular morphology and development. We conclude that site-specific changes in DNA methylation of adult zebrafish testes occur in response to acute developmental TCDD exposure.
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Affiliation(s)
- Camille Akemann
- Department of Pharmacology, Wayne State University, Detroit, MI, United States
| | - Danielle N Meyer
- Department of Pharmacology, Wayne State University, Detroit, MI, United States.,Institute of Environmental Health Sciences, Wayne State University, Detroit, MI, United States
| | - Katherine Gurdziel
- Applied Genome Technology Center, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Tracie R Baker
- Department of Pharmacology, Wayne State University, Detroit, MI, United States.,Institute of Environmental Health Sciences, Wayne State University, Detroit, MI, United States
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22
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Olsvik PA, Whatmore P, Penglase SJ, Skjærven KH, Anglès d'Auriac M, Ellingsen S. Associations Between Behavioral Effects of Bisphenol A and DNA Methylation in Zebrafish Embryos. Front Genet 2019. [PMID: 30906313 DOI: 10.3389/fgene.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023] Open
Abstract
Endocrine-disrupting contaminants have been associated with aberrant changes in epigenetic pathways in animals. In this study, zebrafish embryos were exposed bisphenol A (BPA) to search for associations between behavior and epigenetic mechanisms in fish. For concentration-dependent responses, embryos were exposed to a range of BPA concentrations (0.1 nM to 30 μM). Embryos were analyzed for locomotor activity at 3-, 4-, and 5-days post fertilization (dpf) in response to changing light conditions. Based on concentration-dependent effects on behavior and gene expression, 10 μM BPA [from 24 to 96 hours post fertilization (hpf)] was used for a whole-genome bisulfite sequencing (WGBS) study searching for genome-wide impacts on DNA methylation. Over the examined concentration ranges, hyperactivity was demonstrated for exposures to 0.001 μM BPA in comparison to embryos exposed to lower or higher BPA concentrations. Transcriptional analysis showed significant effects at >0.01 μM BPA for two genes related to DNA methylation (dnmt1, cbs). BPA exposure did not significantly affect global DNA methylation, but 20,474 differentially methylated (DM) sites in 4,873 genes were identified by WGBS analysis. Most DM sites were identified within gene bodies. The genes with the most DM sites were all protocadherin 2 gamma subfamily genes, related to axon targeting, synaptic development and neuronal survival. KEGG pathways most significantly affected by BPA exposure were phosphatidylinositol signaling system, followed by VEGF and MAPK signaling pathways. This study shows that BPA can affect zebrafish embryo swimming activity at very low concentrations as well as affecting numerous methylated sites in genes which are overrepresented in functionally relevant metabolic pathways. In conclusion, altered methylation patterns of genes associated with nervous system development might lead to abnormal swimming activity.
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Patrizi B, Siciliani de Cumis M. TCDD Toxicity Mediated by Epigenetic Mechanisms. Int J Mol Sci 2018; 19:ijms19124101. [PMID: 30567322 PMCID: PMC6320947 DOI: 10.3390/ijms19124101] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 12/11/2018] [Accepted: 12/14/2018] [Indexed: 12/27/2022] Open
Abstract
Dioxins are highly toxic and persistent halogenated organic pollutants belonging to two families i.e., Polychlorinated Dibenzo-p-Dioxins (PCDDs) and Polychlorinated Dibenzo Furans (PCDFs). They can cause cancer, reproductive and developmental issues, damage to the immune system, and can deeply interfere with the endocrine system. Dioxins toxicity is mediated by the Aryl-hydrocarbon Receptor (AhR) which mediates the cellular metabolic adaptation to these planar aromatic xenobiotics through the classical transcriptional regulation pathway, including AhR binding of ligand in the cytosol, translocation of the receptor to the nucleus, dimerization with the AhR nuclear translocator, and the binding of this heterodimeric transcription factor to dioxin-responsive elements which regulate the expression of genes involved in xenobiotic metabolism. 2,3,7,8-TCDD is the most toxic among dioxins showing the highest affinity toward the AhR receptor. Beside this classical and well-studied pathway, a number of papers are dealing with the role of epigenetic mechanisms in the response to environmental xenobiotics. In this review, we report on the potential role of epigenetic mechanisms in dioxins-induced cellular response by inspecting recent literature and focusing our attention on epigenetic mechanisms induced by the most toxic 2,3,7,8-TCDD.
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Affiliation(s)
- Barbara Patrizi
- National Institute of Optics-National Research Council (INO-CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy.
- European Laboratory for Non-Linear Spectroscopy (LENS), Via Nello Carrara 1, 50019 Sesto Fiorentino, Italy.
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From mRNA Expression of Drug Disposition Genes to In Vivo Assessment of CYP-Mediated Biotransformation during Zebrafish Embryonic and Larval Development. Int J Mol Sci 2018; 19:ijms19123976. [PMID: 30544719 PMCID: PMC6321216 DOI: 10.3390/ijms19123976] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 12/07/2018] [Indexed: 12/14/2022] Open
Abstract
The zebrafish (Danio rerio) embryo is currently explored as an alternative for developmental toxicity testing. As maternal metabolism is lacking in this model, knowledge of the disposition of xenobiotics during zebrafish organogenesis is pivotal in order to correctly interpret the outcome of teratogenicity assays. Therefore, the aim of this study was to assess cytochrome P450 (CYP) activity in zebrafish embryos and larvae until 14 d post-fertilization (dpf) by using a non-specific CYP substrate, i.e., benzyloxy-methyl-resorufin (BOMR) and a CYP1-specific substrate, i.e., 7-ethoxyresorufin (ER). Moreover, the constitutive mRNA expression of CYP1A, CYP1B1, CYP1C1, CYP1C2, CYP2K6, CYP3A65, CYP3C1, phase II enzymes uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) and sulfotransferase 1st1 (SULT1ST1), and an ATP-binding cassette (ABC) drug transporter, i.e., abcb4, was assessed during zebrafish development until 32 dpf by means of quantitative PCR (qPCR). The present study showed that trancripts and/or the activity of these proteins involved in disposition of xenobiotics are generally low to undetectable before 72 h post-fertilization (hpf), which has to be taken into account in teratogenicity testing. Full capacity appears to be reached by the end of organogenesis (i.e., 120 hpf), although CYP1-except CYP1A-and SULT1ST1 were shown to be already mature in early embryonic development.
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Falisse E, Ducos B, Stockwell PA, Morison IM, Chatterjee A, Silvestre F. DNA methylation and gene expression alterations in zebrafish early-life stages exposed to the antibacterial agent triclosan. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 243:1867-1877. [PMID: 30408875 DOI: 10.1016/j.envpol.2018.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 09/07/2018] [Accepted: 10/01/2018] [Indexed: 06/08/2023]
Abstract
There is increasing evidence that toxicant exposure can alter DNA methylation profile, one of the main epigenetic mechanisms, particularly during embryogenesis when DNA methylation patterns are being established. In order to investigate the effects of the antibacterial agent Triclosan on DNA methylation and its correlation with gene expression, zebrafish embryos were exposed during 7 days post-fertilization (starting at maximum 8-cells stage) to 50 and 100 μg/l, two conditions for which increased sensitivity and acclimation have been respectively reported. Although global DNA methylation was not significantly affected, a total of 171 differentially methylated fragments were identified by Reduced Representation Bisulfite Sequencing. The majority of these fragments were found between the two exposed groups, reflecting dose-dependant specific responses. Gene ontology analysis revealed that pathways involved in TGF-β signaling were enriched in larvae exposed to 50 μg/l, while de novo pyrimidine biosynthesis functions were overrepresented in fish exposed to 100 μg/l. In addition, gene expression analysis revealed a positive correlation between mRNA levels and DNA methylation patterns in introns, together with significant alterations of the transcription of genes involved in nervous system development, transcriptional factors and histone methyltransferases. Overall this work provides evidence that Triclosan alters DNA methylation in zebrafish exposed during embryogenesis as well as related genes expression and proposes concentration specific modes of action. Further studies will investigate the possible long-term consequences of these alterations, i.e. latent defects associated with developmental exposure and transgenerational effects, and the possible implications in terms of fitness and adaptation to environmental pollutants.
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Affiliation(s)
- Elodie Falisse
- Laboratory of Evolutionary and Adaptive Physiology, Institute of Life, Earth and Environment - University of Namur, 61 rue de Bruxelles, 5000, Namur, Belgium
| | - Bertrand Ducos
- High Throughput qPCR Facility of ENS, IBENS, 46 rue d'Ulm, 75005, PARIS, France
| | - Peter A Stockwell
- Department of Biochemistry, University of Otago, 710 Cumberland Street, Dunedin, 9016, New Zealand
| | - Ian M Morison
- Department of Pathology, Dunedin School of Medicine, University of Otago, 270 Great King Street, Dunedin, 9054, New Zealand
| | - Aniruddha Chatterjee
- Department of Pathology, Dunedin School of Medicine, University of Otago, 270 Great King Street, Dunedin, 9054, New Zealand
| | - Frédéric Silvestre
- Laboratory of Evolutionary and Adaptive Physiology, Institute of Life, Earth and Environment - University of Namur, 61 rue de Bruxelles, 5000, Namur, Belgium.
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26
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Kamstra JH, Hurem S, Martin LM, Lindeman LC, Legler J, Oughton D, Salbu B, Brede DA, Lyche JL, Aleström P. Ionizing radiation induces transgenerational effects of DNA methylation in zebrafish. Sci Rep 2018; 8:15373. [PMID: 30337673 PMCID: PMC6193964 DOI: 10.1038/s41598-018-33817-w] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 10/06/2018] [Indexed: 01/08/2023] Open
Abstract
Ionizing radiation is known to cause DNA damage, yet the mechanisms underlying potential transgenerational effects of exposure have been scarcely studied. Previously, we observed effects in offspring of zebrafish exposed to gamma radiation during gametogenesis. Here, we hypothesize that these effects are accompanied by changes of DNA methylation possibly inherited by subsequent generations. We assessed DNA methylation in F1 embryos (5.5 hours post fertilization) with whole genome bisulfite sequencing following parental exposure to 8.7 mGy/h for 27 days and found 5658 differentially methylated regions (DMRs). DMRs were predominantly located at known regulatory regions, such as gene promoters and enhancers. Pathway analysis indicated the involvement of DMRs related to similar pathways found with gene expression analysis, such as development, apoptosis and cancers, which could be linked to previous observed developmental defects and genomic instability in the offspring. Follow up of 19 F1 DMRs in F2 and F3 embryos revealed persistent effects up to the F3 generation at 5 regions. These results indicate that ionizing radiation related effects in offspring can be linked to DNA methylation changes that partly can persist over generations. Monitoring DNA methylation could serve as a biomarker to provide an indication of ancestral exposures to ionizing radiation.
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Affiliation(s)
- Jorke H Kamstra
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0033, Oslo, Norway.
| | - Selma Hurem
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0033, Oslo, Norway
| | - Leonardo Martin Martin
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0033, Oslo, Norway.,University of Camagüey, Faculty of Agropecuary Sciences, Camagüey, 70100, Cuba
| | - Leif C Lindeman
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0033, Oslo, Norway.,Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - Juliette Legler
- Institute for Environment, Health and Societies, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom.,Utrecht University, Institute for Risk Assessment Sciences, 3508, TD, Utrecht, The Netherlands
| | - Deborah Oughton
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - Brit Salbu
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - Dag Anders Brede
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, 1433, Ås, Norway
| | - Jan Ludvig Lyche
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0033, Oslo, Norway
| | - Peter Aleström
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 0033, Oslo, Norway
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Danion M, Le Floch S, Cabon J, Louboutin L, Morin T. Transchem project - Part II: Transgenerational effects of long-term exposure to pendimethalin at environmental concentrations on the early development and viral pathogen susceptibility of rainbow trout (Oncorhynchus mykiss). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2018; 202:126-135. [PMID: 30025381 DOI: 10.1016/j.aquatox.2018.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 06/27/2018] [Accepted: 07/03/2018] [Indexed: 06/08/2023]
Abstract
In the Transchem project, rainbow trout genitors were exposed to environmental concentrations of pendimethalin over a period of 18 months and two new first generations of offspring, F1_2013 and F1_2014, were obtained. We investigated the impact of direct chemical exposure on juveniles as well as the potential cumulative transgenerational and direct effects on the larval development and on the pathogen susceptibility of offspring. Depending on the chemical treatment or not of the adults, their offspring were distributed in the tanks of our experimental system, in two batches i.e. juveniles from the control genitors (G-) and others from the contaminated ones (G+), and then, half of the tanks were exposed daily to pendimethalin (Off+) while the others were used as controls (Off-). Viral challenges were performed on the offspring, before and after three months of direct chemical exposure, with strains of infectious hematopoietic necrosis virus (IHNV), viral haemorrhagic septicemia virus (VHSV) and sleeping disease alphavirus (SDV). Direct and transgenerational macroscopic effects were observed on offspring, with a percentage of abnormalities in offspring derived from the genitors exposed to pendimethalin (G+) significantly higher compared to those from the genitors from non-exposed group (G-). Before the direct chemical exposure, similar kinetics of mortality was observed between the offspring from the contaminated or control genitors after VHSV infection. With IHNV, the G+ group died in a slightly larger proportion compared to the G- group and seroconversion was greater for the G- group. For the SDV challenge, the mortality was delayed for the G+ offspring compared to the G- and seroconversion reached 65% in the G+ group compared to 45% in the G-, with similar antibody titres. After three months of direct chemical exposure, kinetics of mortality induced by IHNV infection were similar for all groups studied. Infection with SDV resulted in a cumulative mortality of 40% for the G- groups (Off- and Off+), significantly higher than those observed from the contaminated genitors G+. Proportion of seropositivity for SDV varied from 24 to 47% depending on the group, with very low quantities of secreted antibodies. Lastly, the direct exposure of offspring could impact the capacity of fish to adapt their haematological parameters to environmental and physiological changes, and underlines the potential toxic effects on the next generations.
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Affiliation(s)
- Morgane Danion
- French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Ploufragan-Plouzané Laboratory, Fish Viral Pathology Unit, Technopôle Brest-Iroise, 29280 Plouzané, France; European University of Brittany, France.
| | - Stéphane Le Floch
- Centre of Documentation, Research and Experimentation on Accidental Water Pollution (CEDRE), 715 Rue Alain Colas, 29200 Brest, France
| | - Joelle Cabon
- French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Ploufragan-Plouzané Laboratory, Fish Viral Pathology Unit, Technopôle Brest-Iroise, 29280 Plouzané, France; European University of Brittany, France
| | - Lénaïg Louboutin
- French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Ploufragan-Plouzané Laboratory, Fish Viral Pathology Unit, Technopôle Brest-Iroise, 29280 Plouzané, France; European University of Brittany, France
| | - Thierry Morin
- French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Ploufragan-Plouzané Laboratory, Fish Viral Pathology Unit, Technopôle Brest-Iroise, 29280 Plouzané, France; European University of Brittany, France
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Chatterjee N, Gim J, Choi J. Epigenetic profiling to environmental stressors in model and non-model organisms: Ecotoxicology perspective. ENVIRONMENTAL HEALTH AND TOXICOLOGY 2018; 33:e2018015-0. [PMID: 30286591 PMCID: PMC6182246 DOI: 10.5620/eht.e2018015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 09/19/2018] [Indexed: 05/16/2023]
Abstract
Epigenetics, potentially heritable changes in genome function that occur without alterations to DNA sequence, is an important but understudied component of ecotoxicology studies. A wide spectrum of environmental challenge, such as temperature, stress, diet, toxic chemicals, are known to impact on epigenetic regulatory mechanisms. Although the role of epigenetic factors in certain biological processes, such as tumourigenesis, has been heavily investigated, in ecotoxicology field, epigenetics still have attracted little attention. In ecotoxicology, potential role of epigenetics in multi- and transgenerational phenomenon to environmental stressors needs to be unrevealed. Natural variation in the epigenetic profiles of species in responses to environmental stressors, nature of dose-response relationships for epigenetic effects, and how to incorporate this information into ecological risk assessment should also require attentions. In this review, we presented the available information on epigenetics in ecotoxicological context. For this, we have conducted a systemic review on epigenetic profiling in response to environmental stressors, mostly chemical exposure, in model organisms, as well as, in ecotoxicologically relevant wildlife species.
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Affiliation(s)
- Nivedita Chatterjee
- School of Environmental Engineering, University of Seoul, 163 Seoulsiripdaero, Dondaemun-gu, Seoul 02504, Republic of Korea
| | - Jiwan Gim
- School of Environmental Engineering, University of Seoul, 163 Seoulsiripdaero, Dondaemun-gu, Seoul 02504, Republic of Korea
| | - Jinhee Choi
- School of Environmental Engineering, University of Seoul, 163 Seoulsiripdaero, Dondaemun-gu, Seoul 02504, Republic of Korea
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29
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Adam AC, Skjærven KH, Whatmore P, Moren M, Lie KK. Parental high dietary arachidonic acid levels modulated the hepatic transcriptome of adult zebrafish (Danio rerio) progeny. PLoS One 2018; 13:e0201278. [PMID: 30070994 PMCID: PMC6071982 DOI: 10.1371/journal.pone.0201278] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 07/12/2018] [Indexed: 12/18/2022] Open
Abstract
Disproportionate high intake of n-6 polyunsaturated fatty acids (PUFAs) in the diet is considered as a major human health concern. The present study examines changes in the hepatic gene expression pattern of adult male zebrafish progeny associated with high levels of the n-6 PUFA arachidonic acid (ARA) in the parental diet. The parental generation (F0) was fed a diet which was either low (control) or high in ARA (high ARA). Progenies of both groups (F1) were given the control diet. No differences in body weight were found between the diet groups within adult stages of either F0 or F1 generation. Few differentially expressed genes were observed between the two dietary groups in the F0 in contrast to the F1 generation. Several links were found between the previous metabolic analysis of the parental fish and the gene expression analysis in their adult progeny. Main gene expression differences in the progeny were observed related to lipid and retinoid metabolism by PPARα/RXRα playing a central role in mediating changes to lipid and long-chain fatty acid metabolism. The enrichment of genes involved in β-oxidation observed in the progeny, corresponded to the increase in peroxisomal β-oxidative degradation of long-chain fatty acids in the parental fish metabolomics data. Similar links between the F0 and F1 generation were identified for the methionine cycle and transsulfuration pathway in the high ARA group. In addition, estrogen signalling was found to be affected by parental high dietary ARA levels, where gene expression was opposite directed in F1 compared to F0. This study shows that the dietary n-3/n-6 PUFA ratio can alter gene expression patterns in the adult progeny. Whether the effect is mediated by permanent epigenetic mechanisms regulating gene expression in developing gametes needs to be further investigated.
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Affiliation(s)
| | | | - Paul Whatmore
- Institute of Marine Research, Nordnes, Bergen, Norway
| | - Mari Moren
- Institute of Marine Research, Nordnes, Bergen, Norway
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Lanata CM, Chung SA, Criswell LA. DNA methylation 101: what is important to know about DNA methylation and its role in SLE risk and disease heterogeneity. Lupus Sci Med 2018; 5:e000285. [PMID: 30094041 PMCID: PMC6069928 DOI: 10.1136/lupus-2018-000285] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 06/25/2018] [Indexed: 12/20/2022]
Abstract
SLE is a complex autoimmune disease that results from the interplay of genetics, epigenetics and environmental exposures. DNA methylation is an epigenetic mechanism that regulates gene expression and tissue differentiation. Among all the epigenetic modifications, DNA methylation perturbations have been the most widely studied in SLE. It mediates processes relevant to SLE, including lymphocyte development, X-chromosome inactivation and the suppression of endogenous retroviruses. The establishment of most DNA methylation marks occurs in utero; however, a small percentage of epigenetic marks are dynamic and can change throughout a person’s lifetime and in relation to exposures. In this review, we discuss the current understanding of the biology of DNA methylation and its regulators, the measurement and interpretation of methylation marks, the effects of genetics on DNA methylation and the role of environmental exposures with relevance to SLE. We also summarise research findings associated with SLE disease risk and heterogeneity. The robust finding of hypomethylation of interferon-responsive genes in patients with SLE and new associations beyond interferon-responsive genes such as cell-specific methylation abnormalities are described. We also discuss methylation changes associated with lupus nephritis, autoantibody status and disease activity. Lastly, we explore future research directions, emphasising the need for longitudinal studies, cell tissue and context-specific profiling, as well as integrative approaches. With new technologies, DNA methylation perturbations could be targeted and edited, offering novel therapeutic approaches.
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Affiliation(s)
- Cristina M Lanata
- Russell/Engleman Rheumatology Research Center, Department of Medicine, University of California San Francisco, San Francisco, California, USA
| | - Sharon A Chung
- Russell/Engleman Rheumatology Research Center, Department of Medicine, University of California San Francisco, San Francisco, California, USA
| | - Lindsey A Criswell
- Russell/Engleman Rheumatology Research Center, Department of Medicine, University of California San Francisco, San Francisco, California, USA
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31
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Epigenetics in teleost fish: From molecular mechanisms to physiological phenotypes. Comp Biochem Physiol B Biochem Mol Biol 2018; 224:210-244. [PMID: 29369794 DOI: 10.1016/j.cbpb.2018.01.006] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Revised: 01/08/2018] [Accepted: 01/16/2018] [Indexed: 02/07/2023]
Abstract
While the field of epigenetics is increasingly recognized to contribute to the emergence of phenotypes in mammalian research models across different developmental and generational timescales, the comparative biology of epigenetics in the large and physiologically diverse vertebrate infraclass of teleost fish remains comparatively understudied. The cypriniform zebrafish and the salmoniform rainbow trout and Atlantic salmon represent two especially important teleost orders, because they offer the unique possibility to comparatively investigate the role of epigenetic regulation in 3R and 4R duplicated genomes. In addition to their sequenced genomes, these teleost species are well-characterized model species for development and physiology, and therefore allow for an investigation of the role of epigenetic modifications in the emergence of physiological phenotypes during an organism's lifespan and in subsequent generations. This review aims firstly to describe the evolution of the repertoire of genes involved in key molecular epigenetic pathways including histone modifications, DNA methylation and microRNAs in zebrafish, rainbow trout, and Atlantic salmon, and secondly, to discuss recent advances in research highlighting a role for molecular epigenetics in shaping physiological phenotypes in these and other teleost models. Finally, by discussing themes and current limitations of the emerging field of teleost epigenetics from both theoretical and technical points of view, we will highlight future research needs and discuss how epigenetics will not only help address basic research questions in comparative teleost physiology, but also inform translational research including aquaculture, aquatic toxicology, and human disease.
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Ribas L, Vanezis K, Imués MA, Piferrer F. Treatment with a DNA methyltransferase inhibitor feminizes zebrafish and induces long-term expression changes in the gonads. Epigenetics Chromatin 2017; 10:59. [PMID: 29216900 PMCID: PMC5721477 DOI: 10.1186/s13072-017-0168-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 11/30/2017] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The role of epigenetic modifications such as DNA methylation during vertebrate sexual development is far from being clear. Using the zebrafish model, we tested the effects of one of the most common DNA methyltransferase (dnmt) inhibitor, 5-aza-2'-deoxycytidine (5-aza-dC), which is approved for the treatment of acute myeloid leukaemia and is under active investigation for the treatment of solid tumours. Several dose-response experiments were carried out during two periods, including not only the very first days of development (0-6 days post-fertilization, dpf), as done in previous studies, but also, and as a novelty, the period of gonadal development (10-30 dpf). RESULTS Early treatment with 5-aza-dC altered embryonic development, delayed hatching and increased teratology and mortality, as expected. The most striking result, however, was an increase in the number of females, suggesting that alterations induced by 5-aza-dC treatment can affect sexual development as well. Results were confirmed when treatment coincided with gonadal development. In addition, we also found that the adult gonadal transcriptome of 5-aza-dC-exposed females included significant changes in the expression of key reproduction-related genes (e.g. cyp11a1, esr2b and figla), and that several pro-female-related pathways such as the Fanconi anaemia or the Wnt signalling pathways were downregulated. Furthermore, an overall inhibition of genes implicated in epigenetic regulatory mechanisms (e.g. dnmt1, dicer, cbx4) was also observed. CONCLUSIONS Taken together, our results indicate that treatment with a DNA methylation inhibitor can also alter the sexual development in zebrafish, with permanent alterations of the adult gonadal transcriptome, at least in females. Our results show the importance of DNA methylation for proper control of sexual development, open new avenues for the potential control of sex ratios in fish (aquaculture, population control) and call attention to possibly hidden long-term effects of dnmt therapy when used, for example, in the treatment of prepuberal children affected by some types of cancer.
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Affiliation(s)
- Laia Ribas
- Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), Passeig Marítim, 37-45, 08003, Barcelona, Spain
| | - Konstantinos Vanezis
- Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Marco Antonio Imués
- Departamento de Recursos Hidrobiológicos, Universidad de Nariño, Torobajo, Pasto, Colombia
| | - Francesc Piferrer
- Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), Passeig Marítim, 37-45, 08003, Barcelona, Spain.
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Cavalieri V, Spinelli G. Environmental epigenetics in zebrafish. Epigenetics Chromatin 2017; 10:46. [PMID: 28982377 PMCID: PMC5629768 DOI: 10.1186/s13072-017-0154-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/27/2017] [Indexed: 02/06/2023] Open
Abstract
It is widely accepted that the epigenome can act as the link between environmental cues, both external and internal, to the organism and phenotype by converting the environmental stimuli to phenotypic responses through changes in gene transcription outcomes. Environmental stress endured by individual organisms can also enforce epigenetic variations in offspring that had never experienced it directly, which is termed transgenerational inheritance. To date, research in the environmental epigenetics discipline has used a wide range of both model and non-model organisms to elucidate the various epigenetic mechanisms underlying the adaptive response to environmental stimuli. In this review, we discuss the advantages of the zebrafish model for studying how environmental toxicant exposures affect the regulation of epigenetic processes, especially DNA methylation, which is the best-studied epigenetic mechanism. We include several very recent studies describing the state-of-the-art knowledge on this topic in zebrafish, together with key concepts in the function of DNA methylation during vertebrate embryogenesis.
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Affiliation(s)
- Vincenzo Cavalieri
- Laboratory of Molecular Biology and Functional Genomics, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze Edificio 16, 90128, Palermo, Italy. .,Zebrafish Laboratory, Advanced Technologies Network (ATeN) Center, University of Palermo, Viale delle Scienze Edificio 18, 90128, Palermo, Italy.
| | - Giovanni Spinelli
- Laboratory of Molecular Biology and Functional Genomics, Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze Edificio 16, 90128, Palermo, Italy.
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Shaw JLA, Judy JD, Kumar A, Bertsch P, Wang MB, Kirby JK. Incorporating Transgenerational Epigenetic Inheritance into Ecological Risk Assessment Frameworks. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:9433-9445. [PMID: 28745897 DOI: 10.1021/acs.est.7b01094] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Chronic exposure to environmental contaminants can induce heritable "transgenerational" modifications to organisms, potentially affecting future ecosystem health and functionality. Incorporating transgenerational epigenetic heritability into risk assessment procedures has been previously suggested. However, a critical review of existing literature yielded numerous studies claiming transgenerational impacts, with little compelling evidence. Therefore, contaminant-induced epigenetic inheritance may be less common than is reported in the literature. We identified a need for multigeneration epigenetic studies that extend beyond what could be deemed "direct exposure" to F1 and F2 gametes and also include subsequent multiple nonexposed generations to adequately evaluate transgenerational recovery times. Also, increased experimental replication is required to account for the highly variable nature of epigenetic responses and apparent irreproducibility of current studies. Further, epigenetic end points need to be correlated with observable detrimental organism changes before a need for risk management can be properly determined. We suggest that epigenetic-based contaminant studies include concentrations lower than current "EC10-20" or "Lowest Observable Effect Concentrations" for the organism's most sensitive phenotypic end point, as higher concentrations are likely already regulated. Finally, we propose a regulatory framework and optimal experimental design that enables transgenerational epigenetic effects to be assessed and incorporated into conventional ecotoxicological testing.
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Affiliation(s)
- Jennifer L A Shaw
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) , Land and Water, Environmental Contaminant Mitigation and Technologies Research Program, Waite Road, Urrbrae, Adelaide Australia , 5064
| | - Jonathan D Judy
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) , Land and Water, Environmental Contaminant Mitigation and Technologies Research Program, Waite Road, Urrbrae, Adelaide Australia , 5064
- University of Florida , Soil and Water Sciences Department, 1692 McCarthy Drive, Gainesville, Florida 32611, United States
| | - Anupama Kumar
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) , Land and Water, Environmental Contaminant Mitigation and Technologies Research Program, Waite Road, Urrbrae, Adelaide Australia , 5064
| | - Paul Bertsch
- Commonwealth Scientific and Industrial Research Organisation (CSIRO), Land and Water , Brisbane, Queensland Australia , 4001
| | - Ming-Bo Wang
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) , Agriculture and Food Unit, Black Mountain, Canberra, Australian Capital Territory, Australia , 2601
| | - Jason K Kirby
- Commonwealth Scientific and Industrial Research Organisation (CSIRO) , Land and Water, Environmental Contaminant Mitigation and Technologies Research Program, Waite Road, Urrbrae, Adelaide Australia , 5064
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Kamstra JH, Sales LB, Aleström P, Legler J. Differential DNA methylation at conserved non-genic elements and evidence for transgenerational inheritance following developmental exposure to mono(2-ethylhexyl) phthalate and 5-azacytidine in zebrafish. Epigenetics Chromatin 2017; 10:20. [PMID: 28413451 PMCID: PMC5389146 DOI: 10.1186/s13072-017-0126-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 04/04/2017] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Exposure to environmental stressors during development may lead to latent and transgenerational adverse health effects. To understand the role of DNA methylation in these effects, we used zebrafish as a vertebrate model to investigate heritable changes in DNA methylation following chemical-induced stress during early development. We exposed zebrafish embryos to non-embryotoxic concentrations of the biologically active phthalate metabolite mono(2-ethylhexyl) phthalate (MEHP, 30 µM) and the DNA methyltransferase 1 inhibitor 5-azacytidine (5AC, 10 µM). Direct, latent and transgenerational effects on DNA methylation were assessed using global, genome-wide and locus-specific DNA methylation analyses. RESULTS Following direct exposure in zebrafish embryos from 0 to 6 days post-fertilization, genome-wide analysis revealed a multitude of differentially methylated regions, strongly enriched at conserved non-genic elements for both compounds. Pathways involved in adipogenesis were enriched with the putative obesogenic compound MEHP. Exposure to 5AC resulted in enrichment of pathways involved in embryonic development and transgenerational effects on larval body length. Locus-specific methylation analysis of 10 differentially methylated sites revealed six of these loci differentially methylated in sperm sampled from adult zebrafish exposed during development to 5AC, and in first and second generation larvae. With MEHP, consistent changes were found at 2 specific loci in first and second generation larvae. CONCLUSIONS Our results suggest a functional role for DNA methylation on cis-regulatory conserved elements following developmental exposure to compounds. Effects on these regions are potentially transferred to subsequent generations.
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Affiliation(s)
- Jorke H. Kamstra
- Faculty of Veterinary Medicine, Department of Basic Sciences and Aquatic Medicine, CoE CERAD, Norwegian University of Life Sciences, P.O. Box 8146 Dep., 0033 Oslo, Norway
| | - Liana Bastos Sales
- Institute for Environmental Studies, VU University Amsterdam, Amsterdam, The Netherlands
| | - Peter Aleström
- Faculty of Veterinary Medicine, Department of Basic Sciences and Aquatic Medicine, CoE CERAD, Norwegian University of Life Sciences, P.O. Box 8146 Dep., 0033 Oslo, Norway
| | - Juliette Legler
- Institute for Environmental Studies, VU University Amsterdam, Amsterdam, The Netherlands
- Institute for Environment, Health and Societies, College of Health and Life Sciences, Brunel University London, Uxbridge, UK
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Pilsner JR, Parker M, Sergeyev O, Suvorov A. Spermatogenesis disruption by dioxins: Epigenetic reprograming and windows of susceptibility. Reprod Toxicol 2017; 69:221-229. [PMID: 28286111 DOI: 10.1016/j.reprotox.2017.03.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 02/24/2017] [Accepted: 03/02/2017] [Indexed: 02/06/2023]
Abstract
Dioxins are a group of highly persistent chemicals that are generated as by-products of industrial and natural processes. Reduction in sperm counts is among the most sensitive endpoints of dioxin toxicity. The exact mechanism by which dioxins reduce sperm counts is not known. Recent data implicate the role of epididymal factors rather than disruption of spermatogenesis. Studies reviewed here demonstrate that dioxins induce the transfer of environmental conditions to the next generation via male germline following exposures during the window of epigenetic reprogramming of primordial germ cells. Increased incidence of birth defects in offspring of male veterans exposed to dioxin containing, Agent Orange, suggest that dioxins may induce epigenomic changes in male germ cells of adults during spermatogenesis. This is supported by recent animal data that show that environmental conditions can cause epigenetic dysregulation in sperm in the context of specific windows of epigenetic reprogramming during spermatogenesis.
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Affiliation(s)
- J Richard Pilsner
- Department of Environmental Health Sciences, University of Massachusetts Amherst, 686 N. Pleasant St., 171 Goessmann, Amherst, MA 01003-9303, USA.
| | - Mikhail Parker
- Department of Environmental Health Sciences, University of Massachusetts Amherst, 686 N. Pleasant St., 171 Goessmann, Amherst, MA 01003-9303, USA.
| | - Oleg Sergeyev
- Department of Genomics and Human Genetics, Vavilov Institute of General Genetics, Russian Academy of Sciences, 3 Gubkina St., 119991 Moscow, Russia; Chapaevsk Medical Association, 3a Meditsinskaya St., 446100 Chapaevsk, Samara Region, Russia.
| | - Alexander Suvorov
- Department of Environmental Health Sciences, University of Massachusetts Amherst, 686 N. Pleasant St., 171 Goessmann, Amherst, MA 01003-9303, USA.
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Dorts J, Falisse E, Schoofs E, Flamion E, Kestemont P, Silvestre F. DNA methyltransferases and stress-related genes expression in zebrafish larvae after exposure to heat and copper during reprogramming of DNA methylation. Sci Rep 2016; 6:34254. [PMID: 27731414 PMCID: PMC5059630 DOI: 10.1038/srep34254] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 09/08/2016] [Indexed: 12/23/2022] Open
Abstract
DNA methylation, a well-studied epigenetic mark, is important for gene regulation in adulthood and for development. Using genetic and epigenetic approaches, the present study aimed at evaluating the effects of heat stress and copper exposure during zebrafish early embryogenesis when patterns of DNA methylation are being established, a process called reprogramming. Embryos were exposed to 325 μg Cu/L from fertilization (<1 h post fertilization - hpf) to 4 hpf at either 26.5 °C or 34 °C, followed by incubation in clean water at 26.5 °C till 96 hpf. Significant increased mortality rates and delayed hatching were observed following exposure to combined high temperature and Cu. Secondly, both stressors, alone or in combination, significantly upregulated the expression of de novo DNA methyltransferase genes (dnmt3) along with no differences in global cytosine methylation level. Finally, Cu exposure significantly increased the expression of metallothionein (mt2) and heat shock protein (hsp70), the latter being also increased following exposure to high temperature. These results highlighted the sensitivity of early embryogenesis and more precisely of the reprogramming period to environmental challenges, in a realistic situation of combined stressors.
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Affiliation(s)
- Jennifer Dorts
- Research Unit in Environmental and Evolutionary Biology, University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
| | - Elodie Falisse
- Research Unit in Environmental and Evolutionary Biology, University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
| | - Emilie Schoofs
- Research Unit in Environmental and Evolutionary Biology, University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
| | - Enora Flamion
- Research Unit in Environmental and Evolutionary Biology, University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
| | - Patrick Kestemont
- Research Unit in Environmental and Evolutionary Biology, University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
| | - Frédéric Silvestre
- Research Unit in Environmental and Evolutionary Biology, University of Namur, Rue de Bruxelles 61, B-5000 Namur, Belgium
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Hammond SA, Nelson CJ, Helbing CC. Environmental influences on the epigenomes of herpetofauna and fish. Biochem Cell Biol 2016; 94:95-100. [DOI: 10.1139/bcb-2015-0111] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Herpetofauna (amphibians and reptiles) and fish represent important sentinel and indicator species for environmental and ecosystem health. It is widely accepted that the epigenome plays an important role in gene expression regulation. Environmental stimuli, including temperature and pollutants, influence gene activity, and there is growing evidence demonstrating that an important mechanism is through modulation of the epigenome. This has been primarily studied in human and mammalian models; relatively little is known about the impact of environmental conditions or pollutants on herpetofauna or fish epigenomes and the regulatory consequences of these changes on gene expression. Herein we review recent studies that have begun to address this deficiency, which have mainly focused on limited specific epigenetic marks and individual genes or large-scale global changes in DNA methylation, owing to the comparative ease of measurement. Greater understanding of the epigenetic influences of these environmental factors will depend on increased availability of relevant species-specific genomic sequence information to facilitate chromatin immunoprecipitation and DNA methylation experiments.
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Affiliation(s)
- S. Austin Hammond
- Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 1700, STN CSC, Victoria, BC V8W 2Y2, Canada
- Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 1700, STN CSC, Victoria, BC V8W 2Y2, Canada
| | - Christopher J. Nelson
- Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 1700, STN CSC, Victoria, BC V8W 2Y2, Canada
- Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 1700, STN CSC, Victoria, BC V8W 2Y2, Canada
| | - Caren C. Helbing
- Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 1700, STN CSC, Victoria, BC V8W 2Y2, Canada
- Department of Biochemistry and Microbiology, University of Victoria, P.O. Box 1700, STN CSC, Victoria, BC V8W 2Y2, Canada
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Bouwmeester MC, Ruiter S, Lommelaars T, Sippel J, Hodemaekers HM, van den Brandhof EJ, Pennings JL, Kamstra JH, Jelinek J, Issa JPJ, Legler J, van der Ven LT. Zebrafish embryos as a screen for DNA methylation modifications after compound exposure. Toxicol Appl Pharmacol 2016; 291:84-96. [DOI: 10.1016/j.taap.2015.12.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Revised: 12/17/2015] [Accepted: 12/17/2015] [Indexed: 12/19/2022]
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Xu X, Weber D, Martin A, Lone D. Trans-generational transmission of neurobehavioral impairments produced by developmental methylmercury exposure in zebrafish (Danio rerio). Neurotoxicol Teratol 2016; 53:19-23. [DOI: 10.1016/j.ntt.2015.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 10/25/2015] [Accepted: 11/09/2015] [Indexed: 01/28/2023]
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Kamstra JH, Aleström P, Kooter JM, Legler J. Zebrafish as a model to study the role of DNA methylation in environmental toxicology. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:16262-16276. [PMID: 25172464 DOI: 10.1007/s11356-014-3466-7] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 08/14/2014] [Indexed: 06/03/2023]
Abstract
Environmental epigenetics is a rapidly growing field which studies the effects of environmental factors such as nutrition, stress, and exposure to compounds on epigenetic gene regulation. Recent studies have shown that exposure to toxicants in vertebrates is associated with changes in DNA methylation, a major epigenetic mechanism affecting gene transcription. Zebra fish, a well-known model in toxicology and developmental biology, are emerging as a model species in environmental epigenetics despite their evolutionary distance to rodents and humans. In this review, recent insights in DNA methylation during zebra fish development are discussed and compared to mammalian models in order to evaluate zebra fish as a model to study the role of DNA methylation in environmental toxicology. Differences exist in DNA methylation reprogramming during early development, whereas in later developmental stages, tissue distribution of both 5-methylcytosine and 5-hydroxymethylcytosine seems more conserved between species, as well as basic DNA (de)methylation mechanisms. All DNA methyl transferases identified so far in mammals are present in zebra fish, as well as a number of major demethylation pathways. However, zebra fish appear to lack some methylation pathways present in mammals, such as parental imprinting. Several studies report effects on DNA methylation in zebra fish following exposure to environmental contaminants, such as arsenic, benzo[a]pyrene, and tris(1,3-dichloro-2-propyl)phosphate. Though more research is needed to examine heritable effects of contaminant exposure on DNA methylation, recent data suggests the usefulness of the zebra fish as a model in environmental epigenetics.
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Affiliation(s)
- Jorke H Kamstra
- Institute for Environmental Studies, VU University Amsterdam, 1081 HV, Amsterdam, The Netherlands.
| | - Peter Aleström
- Faculty of Veterinary Medicine and Biosciences, Dept. of Basic Science and Aquatic Medicine, Norwegian University of Life Sciences, 0033, Oslo, Norway.
| | - Jan M Kooter
- Department of Molecular Cell Biology, Section Genetics, VU University Amsterdam, 1081 HV, Amsterdam, The Netherlands.
| | - Juliette Legler
- Institute for Environmental Studies, VU University Amsterdam, 1081 HV, Amsterdam, The Netherlands.
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Aluru N, Kuo E, Helfrich LW, Karchner SI, Linney EA, Pais JE, Franks DG. Developmental exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin alters DNA methyltransferase (dnmt) expression in zebrafish (Danio rerio). Toxicol Appl Pharmacol 2015; 284:142-51. [PMID: 25732252 DOI: 10.1016/j.taap.2015.02.016] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Revised: 02/09/2015] [Accepted: 02/13/2015] [Indexed: 01/14/2023]
Abstract
DNA methylation is one of the most important epigenetic modifications involved in the regulation of gene expression. The DNA methylation reaction is catalyzed by DNA methyltransferases (DNMTs). Recent studies have demonstrated that toxicants can affect normal development by altering DNA methylation patterns, but the mechanisms of action are poorly understood. Hence, we tested the hypothesis that developmental exposure to TCDD affects dnmt gene expression patterns. Zebrafish embryos were exposed to 5nM TCDD for 1h from 4 to 5h post-fertilization (hpf) and sampled at 12, 24, 48, 72, and 96 hpf to determine dnmt gene expression and DNA methylation patterns. We performed a detailed analysis of zebrafish dnmt gene expression during development and in adult tissues. Our results demonstrate that dnmt3b genes are highly expressed in early stages of development, and dnmt3a genes are more abundant in later stages. TCDD exposure upregulated dnmt1 and dnmt3b2 expression, whereas dnmt3a1, 3b1, and 3b4 are downregulated following exposure. We did not observe any TCDD-induced differences in global methylation or hydroxymethylation levels, but the promoter methylation of aryl hydrocarbon receptor (AHR) target genes was altered. In TCDD-exposed embryos, AHR repressor a (ahrra) and c-fos promoters were differentially methylated. To characterize the TCDD effects on DNMTs, we cloned the dnmt promoters with xenobiotic response elements and conducted AHR transactivation assays using a luciferase reporter system. Our results suggest that ahr2 can regulate dnmt3a1, dnmt3a2, and dnmt3b2 expression. Overall, we demonstrate that developmental exposure to TCDD alters dnmt expression and DNA methylation patterns.
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Affiliation(s)
- Neelakanteswar Aluru
- Biology Department and Woods Hole Center for Oceans and Human Health, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
| | - Elaine Kuo
- Biology Department and Woods Hole Center for Oceans and Human Health, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA; Stanford University, 450 Serra Mall, Stanford, CA 94305, USA
| | - Lily W Helfrich
- Biology Department and Woods Hole Center for Oceans and Human Health, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA; Northwestern University, 633 Clark St, Evanston, IL 60208, USA
| | - Sibel I Karchner
- Biology Department and Woods Hole Center for Oceans and Human Health, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Elwood A Linney
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Box 3020, Durham, NC 27710, USA
| | - June E Pais
- New England Biolabs, 240 County Road, Ipswich, MA 01938, USA
| | - Diana G Franks
- Biology Department and Woods Hole Center for Oceans and Human Health, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
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