DNA Methylation of Somatic Tissues in Oysters is Influenced by Sex and Heredity.

The influence of sex and heredity on DNA methylation in the somatic tissues of mice has been well-documented, with similar hereditary effects reported in honeybees. However, the extent to which these factors affect DNA methylation in molluscan somatic tissues remains poorly understood. In this study, we investigated genomic DNA methylation patterns in the adductor muscle of two genetically distinct oyster strains using whole-genome bisulfite sequencing (WGBS). Our analysis identified significant differences in DNA methylation between sexes, with females exhibiting a global reduction compared to males. Furthermore, approximately half of the differentially methylated sites between the two parental strains were conserved in their offspring. Regions with differential methylation in parents typically exhibited intermediate methylation levels in the F1 progeny, whereas consistently methylated regions in parents maintained similar methylation levels in their progeny. These findings suggest that offspring DNA methylation is strongly influenced by parental methylation profiles, highlighting its potential role in sexual determination in oysters.