Transcriptome Profiling of the Pacific Oyster Crassostrea gigas Visceral Ganglia over a Reproduction Cycle Identifies Novel Regulatory Peptides

International audienceThe neuropeptides involved in the regulation of reproduction in the Pacific oyster (Crassostrea gigas) are quite diverse. To investigate this diversity, a transcriptomic survey of the visceralganglia (VG) was carried out over an annual reproductive cycle. RNA-seq data from 26 samplescorresponding to VG at different stages of reproduction were de novo assembled to generate a specificreference transcriptome of the oyster nervous system and used to identify differentially expressedtranscripts. Transcriptome mining led to the identification of novel neuropeptide precursors (NPPs)related to the bilaterian Eclosion Hormone (EH), crustacean female sex hormone/Interleukin 17,Nesfatin, neuroparsin/IGFBP, prokineticins, and urotensin I; to the protostome GNQQN, pleurin, prohormones 3 and 4, prothoracotropic hormones (PTTH), and QSamide/PXXXamide; to the lophotrochozoan CCWamide, CLCCY, HFAamide, and LXRX; and to the mollusk-specific NPPs CCCGS,clionin, FYFY, GNamide, GRWRN, GSWN, GWE, IWMPxxGYxx, LXRYamide, RTLFamide, SLRFamide, and WGAGamide. Among the complete repertoire of NPPs, no sex-biased expression wasobserved. However, 25 NPPs displayed reproduction stage-specific expression, supporting theirinvolvement in the control of gametogenesis or associated metabolism