| Cynoglossus semilaevis is one of important economic marine fish which widely distributed in the coastal areas in China,and females grow two to three times faster than males.It is complex to explain sex determination and differentiation mechanism in C.semilaevis,although we have known that its sex determination system is ZZ/ZW.The sex related mechanism is not only influenced by genetic factors,but also affected by environmental factors,and the phenomenon of natural sex reversal from genetic female to phenotypic male was observed.To study sex determination and differentiation mechanism of C.semilaevis is good for cultivating all-female seed,also contributing to promoting the development of its industry.As an ideal model of sex deternination and differentiation research,in-depth study of C.semilaevis sex deternination and differentiation mechanism also has important theoretical significance.In recent years,researches about these are more concentrated in the use of RACE and RT-PCR methods for C.semilaevis gender-related candidate gene cloning,expression analysis and gene function prediction;Sex-related molecular markers screening;Using artificial gynogenesis technology to creat all-female fry and study mechanism of sex determination.Establishing testis,ovary,and pseudo-male gonadal cell lines of C.semilaevis,to provide good tools materials for research of gonadal development process.Screening C.semilaevis families which with high female ratio and growth rate.Vertebrate genetic sex determination and sex differentiation process is generally initiating a series of sex-related genes involved in signal cascade pathway by sex-determining gene which located in the sex chromosome.It will induce a two-way potential primordial germ gonads became to testes or ovaries discrepant differentiation.Therefore,to analysis C.semilaevis early gonadal development process thoroughly,and excavate genes which play an important role in the development process will get a comprehensive understanding of control network and molecular mechanisms of sex determination and differentiation.Based on previous gonadal histological observation in C.semilaevis,we picked five pairs of heterosexual individuals during early differentiation(15dah,36dah,56dah,86dah and 120dah)for RNA-seq by Illlumina Hiseq 2000TM technology.Through sequencing,594,333,590 clean reads were obtained.Using SOAPaligner/SOAP2 software mapping the reads to the reference genome and reference genes.Total mapped reads were about 70%in genome map and 30%～40%in genes map of all reads.On the fundamental of our successfully constructed gonad transcriptome,the differenltially expressed genes were analyzed between 10 libraries of C.semilaevis ovaries and testes.We also get 1207,622,3439,3614 and 11249 DEGs in 15dah,36dah,56dah,86dah and 120dah.Besides,we made the GO enrichment analysis and KEGG enrichment analysis by using these DEGs.To mine and analyze sex related genes in the process of C.semilaevis early gonadal development in system level,gene co-expression network(WGCNA)was performed and 43 modules are obtained,in which 3 modules were detected to be enriched with sex related genes.They were M31,M3 and M39,combining within the module gene,enrichment hub ranking and biological pathways and other information related to three sex-specific functional modules respectively,we got 17,18 and 23 hub genes,and a large number of sex-related genes in the module.We also studied Sox genes in C.semilaevis by using bioinformatics analysis on the standard of whole genome.A total of 23 Sox genes were identified systematically from C.Semilaevis and classified into 7 subfamilies which had not been reported yet.They are subfamily Bi,B2,C,D,E,F and K,each of these groups may have distinct and specific functions.All of members in the family contain 9 amino acid residues(RPMNAFMVW).Baseed on all of these,system analysis conserved domain sequences,evolution,gene structure,chromosomal localization and gene expression patterns was performed.In summary,the present study was to analyze the transcriptome and genome,to some extent the genetic mechanism of C.Semilaevis gonadal development during early sexual differentiation and gonadal development was elucidated.And we revealed biological characteristics of the different developmental stages at the molecular level.Using WGCNA to mine sex related genes,while enhancing understanding of Sox genes in C.semilaevis with bioinformatics analysis.We start sex determination and differentiation research on whole genome-wide level.With the increasing wealth of genomic and other genetic resources,the study also presents a new idea for a number of other important biological questions. |
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