Genome survey and characterization of reproduction-related genes in the Pacific oyster

Reproductive mechanisms in molluscs have been targets for biological research because of the diverse reproductive strategies exhibited in this phylum. However, little is known about the molecular mechanisms of molluscan reproduction. The whole genome sequence of the Pacific oyster Crassostrea gigas together with the transcriptomic data-sets provides a powerful platform for studies on the characterization of the genes involved in bivalve reproduction. Reproduction-related genes were screened in this study through analyzing the Pacific oyster genome. Previously identified molluscan reproduction-related genes were used as queries to a BLASTP search against the C. gigas genome to identify gene candidates encoding similar proteins. Transcriptomic data-sets were analyzed to profile gene candidate expression patterns. We obtained 39 gene candidates with high accuracy encoding reproduction-related genes in the C. gigas genome, of which 17 are reported in detail, and the rest are identified as new candidate genes involved in reproduction of C. gigas, including nanos, piwi, dax1, and 5-hydroxytryptamine (5-HT) receptors. Among 22 gene candidates, seven were gonad-specifically expressed. The set of reproduction-related genes of C. gigas identified in this study constitutes a new tool for further research on molecular mechanisms of reproduction in C. gigas.