Caractérisation et rôle fonctionnel d'une famille de peptides calciotropes (CT et CGRP) (nouvelles données chez un téléostéen et deux mollusques céphalopodes)

Afin de mieux comprendre leur histoire évolutive, nous avons recherché la présence de la CT, du CGRP et de leurs organes cibles, chez un téléostéen, Anguilla anguilla, et deux céphalopodes, Nautilus macromphalus et Sepia officinalis. Contrairement à l anguille, aucune molécule biologiquement apparentée à la CT n a été détectée chez les céphalopodes. La co-localisation du CGRP et de son récepteur dans le système nerveux central de l anguille et de la seiche, suggère que ce peptide pourrait jouer un rôle de neuromédiateur ou neurotransmetteur comme décrit chez les mammifères. L implication du CGRP dans les mécanismes de régulation ionique, de façon endocrine dans les branchies et autocrine/paracrine dans le système rénal, représenterait une fonction ancienne, partagée par les téléostéens et les céphalopodes. Il semble que le CGRP ait une origine ancestrale intervenue avant l émergence des deutérostomiens. La CT constituerait un peptide apparu plus tardivement au cours de l évolution.PARIS-BIUSJ-Thèses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Purification of a functional competitive antagonist for calcitonin gene related peptide action from sardine hydrolysates

Calcitonin gene related peptide (CGRP) related molecules were purified from sardine hydrolysates prepared using 0.1% alcalase and two hours of hydrolysis. Gel exclusion chromatography and HPLC performed purification of these molecules. The purified molecules were characterised using specific CGRP radioimmunoassays and radioreceptoraasays. From 22 mg of crude extract, we obtained 14 μg of CGRP related molecules, the molecular weight determined by mass spectrophotometry was 6000 daltons. The biological activity of these molecules was analysed using the ability of CGRP to stimulate the adenylate cyclase activity in rat liver membranes. The purified molecules induced an inhibition of the CGRP stimulated adenylate cyclase activity, this effect was specific as no such effect was observed on the glucagon stimulated adenylate cyclase activity measured in the same rat liver membrane preparation. These results suggest that the purified molecules may act as antagonists for peptides that bind to CGRP receptors in rat liver membranes. These new antagonists may be of particular importance in various aspects of CGRP action in vertebrates

Peptides from fish and crustacean by-products hydrolysates stimulate cholecystokinin release in STC-1 cells

International audienceFish protein hydrolysates (FPH) are of significant interest, due to their potential application as a source of bioactive peptides in nutraceutical and pharmaceutical domains. Here, we investigated the action of FPH from blue whiting (Micromesistius poutassou) and brown shrimp (Penaeus aztecus) on cholecystokinin release from intestinal endocrine cells (STC-1). We demonstrated for the first time that FPH were able to highly stimulate CCK-releasing activity from STC-1 cells and that this stimulation was mainly due to peptide molecules. The partial purification of CCK-stimulating peptides showed that their apparent molecular weight ranged between 1000 and 1500 Da for fish and crustacean FPH, respectively. Finally, in an aim to industrially produce hydrolysates enriched in CCK-stimulating molecules, we tested the effects of membrane processes (ultrafiltration and nanofiltration) on active peptide enrichment

Purification de calcitonine de vertebres inferieurs

Available from INIST (FR), Document Supply Service, under shelf-number : AR 16011 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEMinistere de la Recherche et de la Technologie (MRT), 75 - Paris (France)FRFranc

Possible role of calcitonin gene-related peptide in osmoregulation via the endocrine control of the gill in a teleost, the eel, Anguilla anguilla

Osmoregulation is a major challenge in aquatic animals involving a complex endocrine control. We investigated the potential role of calcitonin gene-related peptide (CGRP, a neuromediator in mammals) in the endocrine control of the gill in a teleost, the eel. Transfer from freshwater to seawater induced an hyperosmolality and a concomitant large increase in plasma CGRP levels. Specific CGRP binding sites were characterized in the gill and their number was up-regulated after seawater transfer. This study suggests that the endocrine control of gill function during osmoregulation may represent an ancient role of CGRP in vertebrates

Sustained exercise improves vertebral histomorphometry and modulates hormonal levels in rainbow trout

International audienceAbnormal compressions and fusions of vertebral bodies are frequently observed in reared rainbow trout and could result from chronic and unbearable muscle pressures acting oil the axial skeleton during intensive growth. Sustained swimming at moderate speeds was shown to induce many positive effects on growth and swimming performances in salmonids, but yet little is known about ts effects on vertebral remodeling processes and related hormonal regulation. Rainbow trout were subjected to three different swimming speeds (0, 10 and 1.5 body length (BL) s(-1)), starting one month after they were first fed (65 mm) and ending when they reached 260 mm in size (market-size of 275 g) At the end of the experiment, 20 trout were sampled in each lot (N=60) and blood samples were taken. Vertebrae abnormalities were assessed by radiological examinations. Vertebrae from the middle axial region (V32-38) were selected to evaluate bone mineralization (BM) and total bone area (Tt-B.Ar.) on radiographed transverse sections (125 +/- 10 mu m). Assays were performed to evaluate mineral homeostasis (calcemia and phosphatemia), bone cell activities (alkaline phosphatase, ALP, and tartrate-resistant acid phosphatase, TRAP) and bone regulating hormones (calcitonin, CT and thyroid hormones, THs). Sustained exercise reduced the appearance of fused vertebrae, enhanced vertebral BM and decreased vertebral Tt-B.Ar.. while it increased circulating CT and TH levels No variations were observed on mineral homeostasis and bone cell activities. Increasing the swimming speed up to 15 BL s(-1) had positive effects on the vertebral skeleton, and therefore, seems to be a suitable approach to prevent aggravation of vertebral abnormalities in juvenile trout. The changes observed in vertebral features are interpreted as a compromise between the necessity to mobilize vertebral mineral ions in response to various physiological demands and to maintain vertebral strength against mechanical constraint

Biomineralization markers during early shell formation in the European abalone Haliotis tuberculata

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