Project description:Environmental sex determination (ESD) occurs in divergent, phylogenetically unrelated taxa, and in some species co-occurs with genetic sex determination (GSD) mechanisms. Although epigenetic regulation in response to environmental effects has long been proposed to be associated with ESD, a systemic analysis on epigenetic regulation of ESD is still lacking. Using half-smooth tongue sole (Cynoglossus semilaevis) as a model – a marine fish which has both ZW chromosomal GSD and temperature-dependent ESD – we investigated the role of DNA methylation in transition from GSD to ESD by comparing gonadal DNA methylomes of parental females, parental pseudo-males, F1 females, F1 pseudo-males and normal males. To assess the gonadal DNA methylome patterns across different sexual types of tongue sole, we carried out BS-seq on bisulfite converted DNA extracted from adult gonads of parental females, parental pseudo-males, and F1 pseudo-males and females from a cross between a parental pseudo-male and a normal female. We also sampled normal male individuals as a control for the normal male DNA methylation pattern. For each of the five samples, two biological replicates were utilized, with each replicate being pooled by five fish. The phenotype and genotype of each selected fish was identified by the histological analysis and PCR validation using the W chromosome specific marker. DNA were isolated from five pooled gonads of the same replicate, then 5 ?g DNA was used to do the bisulfite conversion and BS-seq. The bisulfite conversion of sample DNA was carried out using a modified NH4HSO3-based protocol (Hayatsu et al. 2006). The paired-end library construction and sequencing were carried out using Illumina HiSeq 2000, according to the manufacturer’s instructions (Illumina). We also mixed 25 ng cl857 Sam7 Lambda DNA in each sample to use as conversion quality control for each library.
Project description:Although hydrogen sulfide is toxic to most organisms, a fish, Poecilia mexicana, has adapted to survive in environments with high levels of hydrogen sulfide. The epigenetic changes in response to this environmental stress were examined by assessing DNA methylation alterations in the nucleated red blood cells (RBC) in the fish. In addition to collecting wild males and females from sulfidic and non-sulfidic environments, wild males and females in these environments were collected and moved to a non-sulfidic environment in the laboratory and propagated for two generations in a non-sulfidic environment. We compared epimutations between sexes and field and laboratory populations. The F0 generation sulfidic wild fish were compared to the non-sulfidic wild fish and found to have significant differential DNA methylation regions (DMRs) in the RBC DNA. The F2 generation laboratory fish were also compared between the sulfidic and non-sulfidic populations, and a significant number of DMRs were also identified. The DMRs have stable generational inheritance in the absence of the sulfidic environment. The DMRs in the F0 generation wild fish had an over 80% overlap with the F2 generation laboratory non-sulfidic environment propagated fish. This is one of the first examples of epigenetic generational stability after the removal of an environmental stressor. The DMR associated genes were found to be relevant to sulfur toxicity and metabolism processes.
2020-12-09 | GSE157730 | GEO
Project description:Environmental DNA monitoring of freshwater fish in Cyprus, 2020
| PRJNA844405 | ENA
Project description:12S rRNA amplicon sequencing of fish from environmental DNA
Project description:In fish, the sex determining mechanisms can broadly be classified as genotypic (GSD), temperature-dependent (TSD), or genotypic plus temperature effects (GSD+TE). For the fish species with TSD or GSD+TE, extremely high or low temperature can affect its sex determination and differentiation. For long time, the underlying changes in DNA methylation that occur during high or low temperature induced sex reversal have not been fully clarified. In this study, we used Nile tilapia as a model to perform a genome-wide survey of differences in DNA methylation in female and male gonads between control and high temperature induced groups using methylated DNA immunoprecipitation (MeDIP). We identified the high temperature induction-related differentially methylated regions (DMRs), and performed functional enrichment analysis for genes exhibiting DMR. These identified differentially methylated genes were potentially involved in the connection between environmental temperature and sex reversal in Nile tilapia. In this study, four samples (control females, CF; control males, CM; induced females, IF; induced males, IM) were analyzed.