ETUDE DU CONTROLE DE LA PONTE CHEZ LA SEICHE SEPIA OFFICINALIS L. (APPLICATIONS A LA CONSERVATION DES STOCKS ET AU REPEUPLEMENT DANS L'OUEST COTENTIN)

CAEN-BU Sciences et STAPS (141182103) / SudocBANYULS/MER-Observ.Océanol. (660162201) / SudocSudocFranceF

Functional micro-anatomy of the digestive gland of the scallop

The digestive gland of Pecten maximus consists, as in other lamellibranchs, of numerous blindending tubules which communicate with the stomach by partially ciliated main ducts and non ciliated secondary ducts. The non-ciliated cells of the main ducts are characterized by a well developed brush border constituted by high and dense microvilli and a strong pinocytotic activity. Ciliated and non ciliated cells have a very similar fine structure. The digestive tubules have a large lumen and contain digestive cells at different stages of absorption, digestion and excretion, one part of the tubules being functional while the other is disintegrating. The dark crypts contain the flagellated secretory cells, characterized by a well developed granular endoplasmic reticulum, and the young immature cells which may replace both the secretory and digestive cells. The numerous lipid droplets occurring in the digestive duct cells and in the digestive cells reveal the lipid storage function of the digestive gland. Several enzyme activities involved in digestion have been localized in the digestive gland. High amylase activity and cellulase and lysozyme activities have been found in the ducts and in the tubules, whereas no proteolytic activity could be detected histochemically. Some intracellular peptidases and glycosidases have been localized in the cells of the digestive gland, especially in the brush-border cells of the ducts and in the functional part of the tubules. High alkaline and acid phosphatase activities are displayed by the duct brush-border cells and the digestive and secretory cells. These results show the main role of the digestive gland, both in extracellular digestion (secretion of the digestive enzymes) and in absorption and intracellular digestion and provide information on the respective functions of the different cells within these processes

Digestive Enzymes in Paralarval Cephalopods

Fourteen enzymes involved in digestion (esterases, glycosidases and peptidases) were localized by histochemical methods in planktonic paralarvae belonging to four families of cephalopods: Octopodidae, Bolitaenidae (Octopods), Ommastrephidae and Enoploteuthidae (Oegopsid squids). The high protease activity and very low or histochemically undetectable amylasic activity indicate a carnivorous diet suggesting that the diet of paralarvae resembles that of adults. The digestive gland displays the highest enzyme activities which agrees with the key role of the gland in the digestive processes of cephalopods. In particular, the gland appears to be the main source of the proteolytic enzymes found in the posterior digestive tract. The high acid phosphatase activity, DAP II and acetyl-glycosaminidase activities, typically lysosomal, point to intracellular digestive processes in the gland. The posterior salivary glands are as well developed in squids as in octopods and they display several enzyme activities, most notably a high proteolytic activity. This could indicate that the salivary glands would be more involved in the digestive processes in paralarval squids than in adults where they are mostly poison glands. In all of the specimens studied, the whole digestive system appears to be already developed and able to digest prey. The high level of alkaline phosphatase activity of the skin suggests active exchanges with the external medium. It seems possible therefore that nutrients could be absorbed through the skin and provide a part of the energy necessary to the young cephalopods

Subcellular distribution of Ag, Cd, Co, Cu, Fe, Mn, Pb and Zn in the digestive gland of the common cuttlefish Sepia officinalis

International audienceThe subcellular fractionation of the digestive gland cells of the common cuttlefish Sepia officinalis was performed in order to investigate the distribution of metals 1) between organelles and cytosol and 2) in the different cytosolic fractions separated by gel-filtration chromatography. Total metal concentrations vary over 3 orders of magnitudes, ranging from 2.2 µg.g-1 dwt for Pb to 612 µg.g-1 dwt for Zn. With the exception of Cd, Co and Cu, metals were mostly bound to the organelles. Whereas no specific organelle compartment was found for Mn, Pb and Zn, Fe was mainly associated to nucleus, brown body, and “boule” fraction (i.e. 52%) and 44% of the total Ag was contained in the lysosomal and mitochondria enriched fraction. The link of metals with hydrosoluble proteins in the cytosolic fraction was investigated at 254 and 280 nm. Direct relationship between cytosolic metal and metallothioneins could only be established for Ag and Cu whereas Cd and Zn seems to mainly bind high (>70kDa) and low (< 4kDa) molecular weight protein

The SepOvotropin: A New Ovarian Peptide Regulating Oocyte Transport in Sepia officinalis

International audienceIn the cuttlefish Sepia officinalis, the successive steps of egg laying are controlled by multiple neuropeptides. Recent experiments led us to suppose that there was possible involvement of a second regulation pathway by the release of ovarian regulatory peptides in the genital tract. Using HPLC fractionation and an in vitro biological test, a C-terminal amidated peptide modulating the motility of the Sepia officinalis oviduct was isolated from an extract of vitellogenic ovarian follicles. The mass of this peptide as determined by MALDI-TOF (1501.8 Da) and analysis by Edman degradation led to the following sequence: Pro-Lys-Asp-Ser-Met-Leu-Leu-Leu-Gln-Val-Pro-Val-Tyr-amide. The peptide mapping performed by LC/MS revealed a distribution restricted to the follicles, the full grown oocytes and the eggs. This new peptide, called SepOvotropin, modulated contractions of the whole genital tract in physiological conditions from a threshold concentration between 10(-20) and 10(-19) M, demonstrating for the first time the occurrence of a specific peptidergic control of egg-laying in cephalopods

In Vitro Synthesis of Proteoglycans and Collagen in Primary Cultures of Mantle Cells from the Nacreous Mollusk, Haliotis tuberculata: A New Model for Study of Molluscan Extracellular Matrix

International audienc

Collagen study and regulation of the de novo synthesis by IGF‐I in hemocytes from the gastropod mollusc, Haliotis tuberculata

International audienc

In Vitro Synthesis of Proteoglycans and Collagen in Primary Cultures of Mantle Cells from the Nacreous Mollusk, Haliotis tuberculata: A New Model for Study of Molluscan Extracellular Matrix

International audienc

Etude des stocks de seiches (Sepia Officinalis L) exloites en Basse-Normandie

CNRS AR 12133 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc