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

Abstract

The 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 visceral ganglia (VG) was carried out over an annual reproductive cycle. RNA-seq data from 26 samples corresponding to VG at different stages of reproduction were de novo assembled to generate a specific reference transcriptome of the oyster nervous system and used to identify differentially expressed transcripts. 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 was observed. However, 25 NPPs displayed reproduction stage-specific expression, supporting their involvement in the control of gametogenesis or associated metabolisms.

Structural and functional characterization of an egg-laying hormone signaling system in a lophotrochozoan – The pacific oyster (Crassostrea gigas)

“…In agreement with a previous work (Réalis-Doyelle et al, 2021), the present study shows that Cragi-ELH gene expression peaks in the VG of reproductively mature male and female oysters. Interestingly, the expression of the Cragi-LXRYamide-encoding gene increased in parallel to that of the Cragi-ELH-encoding gene in the VGs of reproductively mature oysters (Réalis-Doyelle et al, 2021). In addition, LFRFamide signaling regulates reproduction and feeding processes in mollusks (Bigot et al, 2014;Hoek et al, 2005).…”

“…Out of the three neuropeptides generated from the processing of Cragi-ELH1, the C-terminal tetrapeptide LFRYamide (Cragi-ELH1c) exhibited a sequence identical to the C-terminal sequence of Cragi-LXRYamide (Réalis-Doyelle et al, 2021), and its structure clearly resembled that of the LFRFamide family of neuropeptides identified in C. gigas (Bigot et al, 2014). In agreement with a previous work (Réalis-Doyelle et al, 2021), the present study shows that Cragi-ELH gene expression peaks in the VG of reproductively mature male and female oysters. Interestingly, the expression of the Cragi-LXRYamide-encoding gene increased in parallel to that of the Cragi-ELH-encoding gene in the VGs of reproductively mature oysters (Réalis-Doyelle et al, 2021).…”

Laboratoryin vitroreplication of Ostreid Herpes Virus (OsHV-1) using Pacific oyster tissue explants

“…Herpes simplex virus (HSV) infects humans and can remain dormant in nerve tissue (Steiner and Kennedy, 1995). Ganglia can be extracted from Pacific oysters, so it may be possible using explants to examine the role of nervous tissue in the OsHV-1 lifecycle (Réalis-Doyelle et al, 2021).…”