Model

The cuttlefish Sepia officinalis
The common cuttlefish or European common cuttlefish (Sepia officinalis) is one of the largest and best-known cuttlefish species. Exceptionally, large males can reach the size of 50 cm in mantle length (ML) and 4 kg in weight, but usually the average size is ranging for 25 to 35 cm (ML). In the Northern hemisphere, the average size decreases from the north to the south as well as the duration of the life cycle: 22 months in the English Channel against 16-17 months in the Mediterranean sea. . The common cuttlefish is native to at least the west coasts of Africa, the Mediterranean Sea, English Channel, North Sea, and Baltic Sea, although subspecies have been proposed as far south as South Africa. It performs migrations from coastal areas to winter areas to a depth of around 60 to 150 m. As in most cuttlefish species, spawning occurs in shallow waters on specific egg-laying coastal areas.

Scientific Team

Project leaders are Joel Henry and Celine Zatylny-Gaudin from CAEN university

Bioinformatic analysis was conducted by the ABiMS plateforms TEAM

Scientific Context

Control of gamete release and associated behaviors in marine mollusks.
Three types of controllers are considered: (1) neuropeptides associated with the onset of spawning, (2) ovarian regulatory peptides involved in controlling the transport of oocytes in the genital tract and in the secretion of capsular products, (3) peptide and polypeptide sex pheromones suspected of being responsible for the mating and the aggregation of mature cuttlefish on egg-laying areas. Large scale production of transcriptomic data performed since 2012 from organs taken at different stages of maturity, allows for specific analysis in silico based on structural criteria and identify expression products by mass spectrometry. A list of (neuro) peptides candidates were finally established on the basis of tissue and temporal expression patterns.
The functional approach performed with mimetic peptides is based on myotropic tests (contraction of the oviduct, accessory glands of the reproductive tract, ovarian stroma, etc.), cell tests (mainly ovarian follicles) and behavioral tests in Y maze or open space. A comparative approach is also developed on the Sepia officinalis versus Crassostrea gigas to understand the respective levels of involvement of the three types of regulators identified in marine mollusks that exhibit very different reproductive behaviors.

Characterization of peptides and proteins involved in the reproduction and protection of gametes in the cephalopod Sepia officinalis-Analysis of neuropeptidome, ovarian peptidome and secretomes of nidamental glands and salivary glands.

Bioinformatic analysis

The whole S. officinalis transcriptome project includes 15 Illumina libraries (corresponding to male or female posterior salivary glands, different parts of the male or female central nervous system and the female genital apparatus) for a total of 466,282,470 paired-end reads with a maximal read length of 150 bp. The whole raw dataset was filtered and trimmed using PRINSEQ (v 0.20.1) [25] (quality score > 20; mean quality score > 30; minimum length 50 bp; trimming of the poly A/T above 5nt and filtering of low-complexity sequences), then adaptors were trimmed using cutadapt (v 1.0) [26] and finally riboPicker (v 0.4.3) [27] was used to get rid of rRNA contaminants. All along the cleaning process, global sequence quality was checked using FastQC (v 0.10.1) (http://www. bioinformatics.bbsrc.ac.uk/projects/fastqc/). A first global as- sembly was conducted using Trinity (v r2012-10-05) [28], a dedicated package for de novo transcriptomics. We conducted a normalization step according to kmer coverage (kmer of 25 nt and max coverage of 30) proposed by the Trinity package. The inconsistent contigs generated by Trinity were removed after a remapping of reads using Bowtie (v 0.12.8) [29] and the estimation of the relative abundance using RSEM [30] to get the FPKM values (v 1.2.0) (the two software facilities were launched through wrappers provided by the Trinity package). Finally, only transcripts with at least an FPKM value above 1 and isoforms corresponding to more than 1% of the total gene count were kept.