Epigenetic effects of environmental chemicals: Insights from zebrafish

Aluru, Neelakanteswar

doi:10.1016/j.cotox.2017.07.004

Cited by 26 publications

(15 citation statements)

References 89 publications

(73 reference statements)

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“…Zebrafish is a well-established toxicology model system and has been used to study the developmental toxicity of dioxin-like PCBs [ 22 ], as well as the latent effects of developmental exposure [ 23 , 24 ]. The DNA methylomes of different life history stages of developing zebrafish, as well as adult tissues have been sequenced [ 25–28 ].…”

Section: Introductionmentioning

confidence: 99%

Role of DNA methylation in altered gene expression patterns in adult zebrafish (Danio rerio) exposed to 3, 3’, 4, 4’, 5-pentachlorobiphenyl (PCB 126)

Aluru

Karchner

Krick

et al. 2018

Environmental Epigenetics

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There is growing evidence that environmental toxicants can affect various physiological processes by altering DNA methylation patterns. However, very little is known about the impact of toxicant-induced DNA methylation changes on gene expression patterns. The objective of this study was to determine the genome-wide changes in DNA methylation concomitant with altered gene expression patterns in response to 3, 3’, 4, 4’, 5-pentachlorobiphenyl (PCB126) exposure. We used PCB126 as a model environmental chemical because the mechanism of action is well-characterized, involving activation of aryl hydrocarbon receptor, a ligand-activated transcription factor. Adult zebrafish were exposed to 10 nM PCB126 for 24 h (water-borne exposure) and brain and liver tissues were sampled at 7 days post-exposure in order to capture both primary and secondary changes in DNA methylation and gene expression. We used enhanced Reduced Representation Bisulfite Sequencing and RNAseq to quantify DNA methylation and gene expression, respectively. Enhanced reduced representation bisulfite sequencing analysis revealed 573 and 481 differentially methylated regions in the liver and brain, respectively. Most of the differentially methylated regions are located more than 10 kilobases upstream of transcriptional start sites of the nearest neighboring genes. Gene Ontology analysis of these genes showed that they belong to diverse physiological pathways including development, metabolic processes and regeneration. RNAseq results revealed differential expression of genes related to xenobiotic metabolism, oxidative stress and energy metabolism in response to polychlorinated biphenyl exposure. There was very little correlation between differentially methylated regions and differentially expressed genes suggesting that the relationship between methylation and gene expression is dynamic and complex, involving multiple layers of regulation.

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Section: Introductionmentioning

confidence: 99%

Role of DNA methylation in altered gene expression patterns in adult zebrafish (Danio rerio) exposed to 3, 3’, 4, 4’, 5-pentachlorobiphenyl (PCB 126)

Aluru

Karchner

Krick

et al. 2018

Environmental Epigenetics

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“…For this reason, both DNA methylation and histone acetylation in genital ridge were analyzed, however, no changes were found either in 5mC or H3K9ac levels when comparing control to treated embryos. The information about the epigenetic pattern of PGCs in fish is very scarce [45]. In fact, there is only one study correlating the DNA methylation in the promoters of Vasa and cxcr4b in the genital ridge of zebrafish with the expression levels of these two genes [46].…”

Section: Discussionmentioning

confidence: 99%

Embryonic Exposure to Bisphenol A Impairs Primordial Germ Cell Migration without Jeopardizing Male Breeding Capacity

et al. 2019

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A large amount of chemicals are released to the environment each year. Among them, bisphenol A (BPA) is of utmost concern since it interferes with the reproductive system of wild organisms due to its capacity to bind to hormone receptors. Additionally, BPA epigenotoxic activity is known to affect basic processes during embryonic life. However, its effects on primordial germ cells (PGCs) proliferation and migration, both mechanisms being crucial for gametogenesis, remain unknown. To investigate the effects of BPA on PGCs migration and eventual testicle development, zebrafish embryos were exposed to 100, 2000 and 4000 µg/L BPA during the first 24 h of development. Vasa immunostaining of PGCs revealed that exposure to 2000 and 4000 µg/L BPA impaired their migration to the genital ridge. Two pivotal genes of PGCs migration (cxcr4b and sdf1a) were highly dysregulated in embryos exposed to these doses, whereas DNA methylation and epigenetic marks in PGCs and their surrounding somatic cells were not altered. Once embryos reached adulthood, the morphometric study of their gonads revealed that, despite the reduced number of PGCs which colonized the genital ridges, normal testicles were developed. Although H3K9ac decreased in the sperm from treated fishes, it did not affect the progeny development.

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“…For example, it is now known that nestling lab rats, as a result of the properties of their nestling physiological systems, respond to maternal care behaviors in ways that epigenetically alter the function of their adult hypothalamic–pituitary–adrenal axis (Weaver et al 2004 ). Similarly, when zebrafish ( Danio rerio ) are exposed as larvae to a number of environmental toxicants at concentrations so low that no immediate effects can be detected, the fish are subject to multiple, epigenetically mediated alterations in their adult physiology and behavior (Aluru 2017 ; Aluru et al 2017 ).…”

Section: Overview and Conclusionmentioning

confidence: 99%

Youth in the study of comparative physiology: insights from demography in the wild

2020

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Of all the properties of individual animals of interest to comparative physiologists, age and stage of development are among the most consequential. In a natural population of any species, the survivorship curve is an important determinant of the relative abundances of ages and stages of development. Demography, thus, has significant implications for the study of comparative physiology. When Edward Deevey published his influential summary of survivorship in animal populations in the wild seven decades ago, he emphasized “serious deficiencies” because survivorship curves for natural populations at the time did not include data on the earliest life stages. Such data have accumulated over intervening years. We survey, for the first time, empirical knowledge of early-age survivorship in populations of most major animal groups in a state of nature. Despite wide variation, it is almost universally true that > 50% of newly born or hatched individuals die before the onset of sexual maturity, even in species commonly assumed to exhibit high early-age survivorship. These demographic facts are important considerations for studies in comparative and environmental physiology whether physiologists (i) aim to elucidate function throughout the life cycle, including both early stages and adults, or (ii) focus on adults (in which case early-age survivorship can potentially affect adult characteristics through selection or epigenesis). We establish that Deevey’s Type I curve (which applies to species with relatively limited early mortality) has few or no actual analogs in the real, natural world.

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Epigenetic effects of environmental chemicals: Insights from zebrafish

Cited by 26 publications

References 89 publications

Role of DNA methylation in altered gene expression patterns in adult zebrafish (Danio rerio) exposed to 3, 3’, 4, 4’, 5-pentachlorobiphenyl (PCB 126)

Role of DNA methylation in altered gene expression patterns in adult zebrafish (Danio rerio) exposed to 3, 3’, 4, 4’, 5-pentachlorobiphenyl (PCB 126)

Embryonic Exposure to Bisphenol A Impairs Primordial Germ Cell Migration without Jeopardizing Male Breeding Capacity

Youth in the study of comparative physiology: insights from demography in the wild

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