报 告 人：Jose Domingos

机 构：James Cook University

报告题目：Epigenetic Changes of Sex Genes Induce Sex Reversal in Asian Seabass Lates calcarifer

Abstract

Asian seabass(Lates calcarifer)is an emergent aquaculture fish species with excellent farming attributes.However,Asian seabass breeding programs to boost productivity are hindered by a lack of reproductive control.Asian seabass,being a large protandrous hermaphrodite,change sex from male to female at 3-5 years of age.The genetic mechanisms leading to this sex-change have not been elucidated and there is currently no intervention option available for hatchery managers to control or speed up the sex transition process.

Recent research strongly suggests that epigenetics plays a critical role in determining gonadal fate in some fishes.In sequential hermaphrodites like Asian seabass where male and female genomes are identical,it is possible that cumulative changes in gonadal CpG methylation methylation profiles beyond a threshold level may trigger male to female sex reversal.In this study,DNA methylation of 146 CpG sites and gene expression analyses were examined in seven sex-related genes(dmrtl,cyp19al,amh,fox12,nr5a2,sox8 and sox9)of 24 testis and 18 ovaries of captive and wild adult Asian seabass using next-generation bisulfite amplicon sequencing,RNA-seq and RT-qPCR approaches.Comparatively,cyp19al and amh were more methylated in males,whereas dmrtl and nr5a2 were more methylated in females(P<0.001),with no sex differences found for foxl2,sox8 or sox9 genes(P>0.05).Notably,differential DNA methylation was associated with alternative aplicing of bothdmrtl and cyp19a1,whereby males lacked the full-length aromatase coding cyp19a1 mRNA,and females lacked the dmrtl exon containing the DM-domain sequence.

Deep sequencing data suggests that DNA methylation of proximl promoters may be involved in the maintenance of alternative gonadal phenotypes in Asian seabass,not necessarily by repressing gene expression,but possibly through the mediation of nonfunctional dmtrl and cyp19al spliced transcripts in ovaries and testes,respectively.Moreover,this work suggests that gene-specific methylation/demethylation changes during Asian seabass adulthood are key biological processes underlying sex reversal.Further investigation on factors which may accelerate epigenetic changes will lead to better broodstock sex-control and contribute to efficient breeding programs for hermaphrodite fishes like Asian seabass.

时 间：2017. 9. 5（周二）9:30-10:30

地 点：生命学院化学馆一楼学术厅