Gonad Transcriptome Analysis of the Pacific Oyster Crassostrea gigas Identifies Potential Genes Regulating the Sex Determination and Differentiation Process
The Pacific oyster Crassostrea gigas is a commercially important bivalve in aquaculture worldwide. C. gigas has a fascinating sexual reproduction system consisting of dioecism, sex change, and occasional hermaphroditism, while knowledge of the molecular mechanisms of sex determination and differentiation is still limited. In this study, the transcriptomes of male and female gonads at different gametogenesis stages were characterized by RNA-seq. Hierarchical clustering based on genes differentially expressed revealed that 1269 genes were expressed specifically in female gonads and 817 genes were expressed increasingly over the course of spermatogenesis. Besides, we identified two and one gene modules related to female and male gonad development, respectively, using weighted gene correlation network analysis (WGCNA). Interestingly, GO and KEGG enrichment analysis showed that neurotransmitter-related terms were significantly enriched in genes related to ovary development, suggesting that the neurotransmitters were likely to regulate female sex differentiation. In addition, two hub genes related to testis development, lncRNA LOC105321313 and Cg-Sh3kbp1, and one hub gene related to ovary development, Cg-Malrd1-like, were firstly investigated. This study points out the role of neurotransmitter and non-coding RNA regulation during gonad development and produces lists of novel relevant candidate genes for further studies. All of these provided valuable information to understand the molecular mechanisms of C. gigas sex determination and differentiation.
KeywordsGonad transcriptome Sex determination and differentiation Reproductive regulation Weighted gene correlation network analysis Crassostrea gigas
This work was supported by the grants from National Natural Science Foundation of China (31772843, 31672649), Shandong Province (2016ZDJS06A06), Fundamental Research Funds for the Central Universities (201762014), and Major Project for Tianjin Seed Technology (15ZXZYNC00050).
CY carried out the molecular genetic studies, participated in the data analysis, and drafted the manuscript. QL conceived of the study, participated in experimental design and coordination, and contributed to the manuscript preparation. HY participated in the data analysis. All authors read and approved the final manuscript.
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Conflict of Interest
The authors declare that they have no conflict of interest.
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