Analysis of gonad differentiation in zebrafish by histology and transgenics

Abstract

The differentiation of male zebrafish involves the formation of a a??juvenile ovarya?? which later degenerates and transforms into a testis. In this study, EGFP from vas:egfp transgenic zebrafish was found to be a useful marker to collect individuals undergoing gonad transformation. These individuals were then analyzed by real-time PCR, in situ hybridization and custom-made microarray which contains over 6,300 gonad-derived unique cDNAs isolated in our laboratory.The results lead to a hypothesis that the down-regulation of aromatase cyp19a1a by anti-m??llerin hormone (amh) may be the mechanism of a??juvenile ovary-to-testisa?? transformation. The data also suggest that 11I?-hydroxylase (cyp11b) or its product 11-ketotestosterone does not appear to be the inducer for testis differentiation or gonad transformation in zebrafish, as proposed by studies performed on other teleosts. Comparative global analysis of transcriptomes between transforming gonads and non-transforming gonads (ovaries) identified over 200 other genes differentially expressed by at least 2 fold during transformation.