Epigenetic changes after rearing zebrafish (Danio rerio) at high density conditions during gonadal development

VIII Jornada de Cromatina i Epigenètica organizada por la Secció de Cromatina i Epigenètica de la Societat Catalana de Biologia (SCB) con el Barcelona Chromatin Club (BCC), 16 March 2018, Barcelona.-- 1 pageStress induced by high rearing density during the gonadal development period (7 to 45 days post fertilization, dpf) in domesticated zebrafish (Danio rerio) caused an increase in the number of males. Moreover, the ovarian transcriptome of fish subjected to high density had more than 3,000 differentially expressed genes (DEG) when compared to non-stressed fish. Further, it is known that DNA methylation is related to the masculinization process in fish during gonadal development. Thus, the goal of this study was to determine whether there was a direct relationship between stress and DNA methylation changes in fish gonads. Zebrafish larvae were subjected to two different treatments, one group reared at low density (9 fish/liter) and another group reared at high density (74 fish/liter) during their sexual differentiation period. Once fish reached adulthood, sex ratio and biometry were recorded and gonads were dissected and kept frozen at -80ºC. In order to test how DNA methylation patterns changed due to density, a set of eleven DEG related to sex (e.g., cyp19a1a and dmrt1), stress (e.g., β-hsd) and DNA methylation (e.g., dnmt1) were selected and analyzed by Multiplex Bisulfite Sequencing (MBS) to obtain the methylation level for each CpG in the promoter regions. Sequencing data was analyzed by bioinformatics tools (e.g., Bismark software) and results discussed in relation to the ability of high density stress as an environmental factor capable to cause long-lasting effects through changes in the DNA methylationPeer Reviewe