Abstract
YY super-males have rarely been detected in nature and only been artificially created in some fish species including tilapia and yellow catfish (Pelteobagrusfulvidraco), which provides a promising model for testis development and spermatogenesis. In our previous study, significant differences in morphology and miRNA expression were detected between XY and YY testis of yellow catfish. Here, solexa sequencing technology was further performed to compare mRNA expression between XY and YY testis. Compared with unigenes expressed in XY testis, 1146 and 1235 unigenes have significantly higher and lower expression in YY testis, respectively. 605 differentially expressed unigenes were annotated to 1604 GO terms with 319 and 286 genes having relative higher expression in XY and YY testis. KEGG analysis suggested different levels of PI3K-AKT and G protein-coupled receptor (GPCR) signaling pathways between XY and YY testis. Down-regulation of miR-141/429 in YY testis was speculated to promote testis development and maturation, and several factors in PI3K-AKT and GPCR signaling pathways were found as predicted targets of miR-141/429, several of which were confirmed by dual-luciferase reporter assays. Our study provides a comparative transcriptome analysis between XY and YY testis, and reveals interactions between miRNAs and their target genes that are possibly involved in regulating testis development and spermatogenesis.
Highlights
Sex determination and differentiation are the most significant developmental events that direct the embryonic gonads into either testes or ovaries [1,2]
In vertebrates with XY sex-determining system, the expression of sex-determining gene on Y chromosome leads to the development of male phenotypes and testis
Herrera et al found that YY tilapia has superior reproductive capacity than XY fish, since the primordial germ cells and spermatogenic cells in YY were larger than XY fish during gonad development and the lobules, blastemal of the reproductive duct and mature sperm cells appeared earlier in YY than XY fish
Summary
Sex determination and differentiation are the most significant developmental events that direct the embryonic gonads into either testes or ovaries [1,2]. Comparative Transcriptome Analysis of XY and YY Testis sex-determining genes, triggering differentiation of testes from bi-potential gonads in mammals and birds [3,4]. Multiple sex-determining genes including dmy/dmrt1Y and dmrt in Oryzias latipes [5,6], gsdf in Oryzias luzonensis [7], sox in Oryzias dancena [8], amhy in Odontesthes hatchery [9], sdY in Oncorhynchus mykiss [10], amhr in Takifugu rubripes [11] and dmrt in Cynoglossus semilaevis [12] have been identified to participate in the male sex determination in different fish species. Several important genes such as cyp19a1, foxl, wnt for ovary differentiation and dmrt, sox, amh for testicular differentiation have been revealed in teleosts [13,14,15]
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