ETUDE DU METABOLISME DU GLYCOGENE CHEZ L'HUITRE CREUSE CRASSOSTREA GIGAS. IMPACT SUR LA REPRODUCTION ET LES MORTALITES ESTIVALES

CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Lexicon of histological structures found in the ovaries and during the oogenesis of the four-spot megrim, Lepidorhombus boscii (Risso, 1810)

Lexicon describing, in depth, the cellular structures found within the Four-spot megrim's ovaries, and during the oogenesis

Lexicon of histological structures found in the ovaries and during the oogenesis of the megrim, Lepidorhombus whiffiagonis (Walbaum, 1792)

Lexicon describing, in depth, the cellular structures found within the megrim's ovaries, and during the oogenesis

Molecular evolution and functional characterisation of insulin related peptides in molluscs: Contributions of Crassostrea gigas genomic and transcriptomic-wide screening

International audienceInsulin Related Peptides (IRPs) belong to the insulin superfamily and possess a typical structure with two chains, B and A, linked by disulphide bonds. As the sequence conservation is usually low between members, IRPs are classified according to the number and position of their disulphide bonds. In molluscan species, the first IRPs identified, named Molluscan Insulin-related Peptides (MIPs), exhibit four disulphide bonds. The genomic and transcriptomic data screening in the Pacific oyster Crassostrea gigas (Mollusc, Bivalvia) allowed us to identify six IRP sequences belonging to three structural groups. Cg-MIP1 to 4 have the typical structure of MIPs with four disulphide bonds. Cg-ILP has three disulphide bonds like vertebrate Insulin-Like Peptides (ILPs). The last one, Cg-MILP7 has a significant homology with Drosophila ILP7 (DILP7) associated with two additional cysteines allowing the formation of a fourth disulphide bond. The phylogenetic analysis points out that ILPs may be the most ancestral form. Moreover, it appears that ILP7 orthologs are probably anterior to lophotrochozoa and ecdysozoa segregation. In order to investigate the diversity of physiological functions of the oyster IRPs, we combine in silico expression data, qPCR measurements and in situ hybridization. The Cg-ilp transcript, mainly detected in the digestive gland and in the gonadal area, is potentially involved in the control of digestion and gametogenesis. The expression of Cg-mip4 is mainly associated with the larval development. The Cg-mip transcript shared by the Cg-MIP1, 2 and 3, is mainly expressed in visceral ganglia but its expression was also observed in the gonads of mature males. This pattern suggested the key roles of IRPs in the control of sexual reproduction in molluscan species

Morphological and molecular criteria allow the identification of putative germ stem cells in a lophotrochozoan, the Pacific oyster Crassostrea gigas

International audienceWhile our knowledge of bivalve gametogenesis recently progressed, data on early stages of gametogenesis remain to be developed, especially when dealing with germinal stem cells (GSC) and their niche in these organisms. Here, we wish to develop a strategy to identify putative GSC in Pacific oyster Crassostrea gigas based on morphological criteria combined with vasa marker expression. A histological quantitative approach, based on stereology, allowed us to identify two types of early germ cells in the germinal epithelium, one presenting round nuclei and the other irregular ones. Both early germ cell types present slightly condensed chromatin in nucleus, are vasa-positive and the Oyvlg (oyster vasa-like gene) expression in these cells is recorded throughout the whole gametogenesis process. The microenvironment of an early germ cell in oyster includes an associated somatic cell presenting an immunolabeling for BMP2/4 and a close myoid cell. In agreement with the GSC characteristics in other species, we postulate that putative germ stem cells in C. gigas correspond to the early germ cell type with irregular nucleus shape; those early germ cells with a round nucleus may consist in progenitors

Data for evolutive analysis of insulin related peptides in bilaterian species

In bilaterian species, the amino acid sequence conservation between Insulin related peptides is relatively low except for the cysteine residues involved in the disulphide bonds. In the A chain, the conserved cystein residues are included in a signature motif. Investigating the variations in this motif would give insight into the phylogenetic history of the family. The table presented in this paper contains a large set of insulin-related peptides in bilateral phylogenetic groups (deuterostomian, ecdysozoan, lophotrochozoan). NCBI databases in silico wide screening combined with bibliographic researches provided a framework for identifying and categorising the structural characteristics of these insulin related peptides. The dataset includes NCBI IDs of each sequence with hyperlinks to FASTA format. Moreover, the structural type (α, β or γ), the A chain motif, the total number of cysteins, the C peptide cleavage mode and the potential additional domains (D or E) are specified for each sequence. The data are associated with the research article “Molecular evolution and functional characterisation of insulin-related peptides in molluscs: contributions of Crassostrea gigas genomic and transcriptomic-wide screening” [1]. The table presented here can be found at http://dx.doi.org/10.17632/w4gr8zcpk5.4#file-21c0f6a5-a3e3-4a15-86e0-e5a696458866

Proteomic identification of protein associated to mature spermatozoa in the Pacific oyster Crassostrea gigas

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Male germ cells of the Pacific oyster

A technique was developed for dissection and isolation of male germ cells in the oyster Crassostrea gigas. This procedure can provide cells for the exploration of processes involved in the reproductive physiology of bivalves. Spermatogonia were chosen because of their essential role in spermatogenesis and the impact of gonia proliferation on reproductive effort. A non lethal method for determining sex and reproductive cycle stage was first validated in oysters. This first step was essential in order to constitute a homogeneous pool of oysters at the same stages of gametogenesis. Germ cell fractions were then obtained from a density gradient, and enrichment of each fraction was ratified by electron microscopy and by means of a 2-parameter flow cytometry procedure (DNA and mitochondrial staining). A significant enrichment in spermatogonia and spermatocytes was confirmed by the increased expression of markers of proliferative cells (proliferative cell nuclear antigen, PCNA) and early germ cells (oyster vasa-like gene). A preliminary cell sorting procedure is also reported, which was applied to fractions enriched in spermatogonia

Sample collection protocol for the extraction of female gonads in the megrim (Lepidorhombus spp.) for maturity staging through histology

This protocol was established during project MATO (MATurité Objective des poissons par l’histologie quantitative) for the evaluation of sexual maturity of exploited stock species, as well as to harmonize the sampling process of gonad extraction before the mounting between slide and slip of the gonad sections. This document follows the work of different workshops that aimed to improve the compilation of data on sexual maturity. The WKMATCH (WorKshop for MATurity staging CHairs, 2012) defined a universal evaluation grid for sexual maturity staging of different species. During this workshop, two main recommendations were made, underlining the need to improve and complete the knowledge on sexual maturity, as well as to harmonize the practices used to determine these sexual phases. This sampling protocol will be restricted to the female gonad of the megrim