Effects of a parental exposure to diuron on Pacific oyster spat methylome

Abstract

Environmental epigenetic is an emerging field that studies the cause–effect relationship between environmental factors and heritable trait via an alteration in epigenetic marks. This field has received much attentions since the impact of environmental factors on different epigenetic marks have been shown to be associated with a broad range of phenotypic disorders in natural ecosystems. Chemical pollutants have been shown to affect immediate epigenetic information carriers of several aquatic species but the heritability of the chromatin marks and the consequences for long term adaptation remain open questions. In this work, we investigated the impact of the diuron herbicide on the DNA methylation pattern of spat from exposed Crassotrea gigas genitors. This oyster is one of the most important mollusk species produced worldwide and a key coastal economic resource in France. The whole genome bisulfite sequencing (WGBS, BS-Seq) was applied to obtain a methylome at single nucleotide resolution on DNA extracted from spat issued from diuron exposed genitors comparatively to control spat. We showed that the parental diuron exposure has an impact on the DNA methylation pattern of its progeny. Most of the differentially methylated regions occurred within coding sequences and we showed that this change in methylation level correlates with RNA level only in a very small group of genes. Although the DNA methylation profile is variable between individuals, we showed conserved DNA methylation patterns in response to parental diuron exposure. This relevant result opens perspectives for the setting of new markers based on epimutations as early indicators of marine pollutions.

Population epigenetic divergence exceeds genetic divergence in the Eastern oyster Crassostrea virginica in the Northern Gulf of Mexico

“…differences observed here are a snapshot of methylation states that are shaped by the environmental conditions at the time of collection. The presence of shared methylation states between individuals within a site strengthens the case for exploring potential intergenerational inheritance of these methylation patterns as was recently demonstrated in C. gigas following parental exposure to the herbicide diuron(Rondon et al, 2017).F I G U R E 6 (a) Per locus P ST plotted against F ST for loci shared between the two datasets. The red spot identifies the intersection of the observed mean F ST and mean P ST for all loci.…”

Convergence of DNA methylation profiles in a novel environment in the reef coral Porites astreoides

“…Age-related changes in methylation, for example, are well-documented among humans and other vertebrates (Horvath 2013), and there is also some evidence among invertebrates (Lian et al 2015). Meanwhile, several studies have noted considerable variance in methylation patterns that is incompletely explained by genetics and known environmental conditions (Dimond et al 2017;Durante et al 2019;Rondon et al 2017). However, the significant convergence of colony methylation profiles after a year in the common garden together suggest that methylation was in fact responding to, and reflective of, the common garden environment.…”

Nurtured by nature: Considering the role of environmental and parental legacies in coral ecological performance

“…DNA methylation and other epigenetic mechanisms linked to gene expression regulation (Putnam et al, 2016; Putnam & Gates, 2015; Torda et al, 2017) could also provide a mechanism of heritable cross-generational priming. Identification of differential DNA methylation patterns between the offspring of exposed and unexposed oysters is an initial line of evidence for an epigenetic role in TGP for marine calcifiers (Rondon et al, 2017). The minute number of methylation changes and the lack of direct impact on RNA transcript abundance or differential splicing (Rondon et al, 2017), however, illustrates how complex these mechanisms can be.…”

“…Identification of differential DNA methylation patterns between the offspring of exposed and unexposed oysters is an initial line of evidence for an epigenetic role in TGP for marine calcifiers (Rondon et al, 2017). The minute number of methylation changes and the lack of direct impact on RNA transcript abundance or differential splicing (Rondon et al, 2017), however, illustrates how complex these mechanisms can be. While differential provisioning of planulae symbiotically, energetically, and epigenetically is possible, the goal of examining ecological effects on the process of recruitment precluded destructive sampling for such hypotheses in our study, but they remain important considerations in future work.…”