Limites de la méthode de reconnaissance de l'origine (marine ou dulcicole) de la truite (Salmo trutta L.) au moyen de l'analyse de la teneur en strontium des écailles

National audienceStrontium content of scales of anadromous and freshwater trout caught in rivers in Basse-Normandie, varies with drainage basin, time spent in the sea and date of capture. The influence of this last factor is probably in relation to sexual maturation.La teneur en strontium des écailles de truites, d'origines anadrome et dulcicole, capturées dans des rivières de Basse-Normandie, dépend du réseau hydrographique, du temps de séjour en mer et de la date de capture. L'influence de ce dernier facteur est probablement liée à la maturation sexuelle

Exemples de résultats de la recherche obtenus sur les populations sauvages de salmonides de Bretagne et de Basse-Normandie et applicables à leur gestion

Ces dernières années, un ensemble de méthodes et techniques d'étude a été mis au point ou amélioré à partir de recherches réalisées sur les populations sauvages de salmonides. Dans un premier temps, ces nouvelles techniques peuvent être considérées comme des outils disponibles pour les gestionnaires; ce sont : la mise en place et l'homogénéisation de critères scalimétriques pour la détermination de l'âge des salmonidés migrateurs; la détermination du sexe par sérodiagnostic et à partir de critères morphométriques; l'estimation de la production en smolts de saumon à partir de l'habitat et des caractéristiques des peuplements automnaux. Dans un deuxième temps, l'application de certaines de ces méthodes dans le domaine écologique a permis d'obtenir des éléments essentiels pour la connaissance et/ou la gestion des populations sauvages de salmonides.Turing the fast few years some new techniques for the study of wild populations of salmonids have been developed. The following procedures are intended to provide.1) an improved method for determining age by scale-reading, particularly with migratory salmonids (Atlantic salmon and sea trout). A standard zone for removing scales, the presence of three different zones on each scale (river, run-out, sea) and some criteria for scale interpretation have all been defined. These criteria are mainly concerned with the structure of the scale during the sea-life stage and reproduction. On the other hand, a spawning mark has been determined for both sedentary and migratory salmonids.2) an means of sex determination. Two techniques have been proposed :- the first one is based on the detection by immunoagglutination of the serum vitellogenin of females in active gametogenesis. This method concerns females only; it does not allow a distinction to he made between non spermating males and immature salmonids. It is a very reliable technique which can be used in field conditions, but only by experienced researchers;- the second technique is based on the sexual dimorphism of the relative length of the upper jaw bone. It is very reliable (8 % to 12 % error) and can also be applied in field conditions, but only for large fish (fork length > 40-45 cm).3) a way of estimating Atlantic salmon smolt production. This technique is based on :- the estimation of a 0+ and 1+ salmon population in the whole river from data of density obtained in sectors representative of the different types of habitat ;- the presence of growth bimodality in a 0+ salmon population in autumn, given the following hypothesis : one yearold smolts belong to the upper mode ;- the estimation of mortality for the whole winter season.This technique has been used in the River Oir and compared with a smolt-trapping experiment conducted for two years. A comparison of the results shows that :- the one year-old smolts belong to the upper mode of bimodality;- when based on data on habitat characteristics, this technique can be used in field conditions to evaluate the smolts with sufficient accuracy.All three techniques are immediately available as useful methods for fisheries management. At a second stage, they can also serve in ecological research to advance knowledge on which to base further study and improved management of wild salmonid populations

Observations sur la reproduction artificielle de l'ombre commun (Thymallus thymallus)

National audienceVarious observations and results of experiments carried out in the hatchery of the "Conseil Supérieur de la Pêche" in Augerolles are presented, concerning the technics of artificials pawning adapted to the physiology of grayling . It is shown that th e physiological characteristics are nearly t he same as those of brown trout . Nevertheless highs ensitivity to low temperatures reduces the speed of the finaloocyte maturation. These observations and experiments lead the authors to give practical recommendations.Diverses observations et résultats d'expériences réalisées à la Salmoniculture du Conseil Supérieur de la Pêche à Augerolles sont présentés, concernant les techniques de reproduction artificielle adaptées à la physiologie de l'Ombre commun. Les caractéristiques physiologiques mises en évidence sont proches de celles de la Truite avec cependant une sensibilité accrue aux basses températures , qui peuvent ralentir très fortement la fin de la maturation ovocytaire. Ces observations et expériences conduisent les auteurs à formuler un certain nombre de conseils pratiques

Regulation of p73 activity by post-translational modifications

The transcription factor p73 is a member of the p53 family that can be expressed as at least 24 different isoforms with pro- or anti-apoptotic attributes. The TAp73 isoforms are expressed from an upstream promoter and are regarded as bona fide tumor suppressors; they can induce cell cycle arrest/apoptosis and protect against genomic instability. On the other hand, ΔNp73 isoforms lack the N-terminus transactivation domain; hence, cannot induce the expression of pro-apoptotic genes, but still can oligomerize with TAp73 or p53 to block their transcriptional activities. Therefore, the ratio of TAp73 isoforms to ΔNp73 isoforms is critical for the quality of the response to a genomic insult and needs to be delicately regulated at both transcriptional and post-translational level. In this review, we will summarize the current knowledge on the post-translational regulatory pathways involved to keep p73 protein under control. A comprehensive understanding of p73 post-translational modifications will be extremely useful for the development of new strategies for treating and preventing cancer

SIRT1 Undergoes Alternative Splicing in a Novel Auto-Regulatory Loop with p53

Background: The NAD-dependent deacetylase SIRT1 is a nutrient-sensitive coordinator of stress-tolerance, multiple homeostatic processes and healthspan, while p53 is a stress-responsive transcription factor and our paramount tumour suppressor. Thus, SIRT1-mediated inhibition of p53 has been identified as a key node in the common biology of cancer, metabolism, development and ageing. However, precisely how SIRT1 integrates such diverse processes remains to be elucidated. Methodology/Principal Findings: Here we report that SIRT1 is alternatively spliced in mammals, generating a novel SIRT1 isoform: SIRT1-DExon8. We show that SIRT1-DExon8 is expressed widely throughout normal human and mouse tissues, suggesting evolutionary conservation and critical function. Further studies demonstrate that the SIRT1-DExon8 isoform retains minimal deacetylase activity and exhibits distinct stress sensitivity, RNA/protein stability, and protein-protein interactions compared to classical SIRT1-Full-Length (SIRT1-FL). We also identify an auto-regulatory loop whereby SIRT1-DExon8 can regulate p53, while in reciprocal p53 can influence SIRT1 splice variation. Conclusions/Significance: We characterize the first alternative isoform of SIRT1 and demonstrate its evolutionary conservation in mammalian tissues. The results also reveal a new level of inter-dependency between p53 and SIRT1, two master regulators of multiple phenomena. Thus, previously-attributed SIRT1 functions may in fact be distributed betwee

The F-box protein FBXO45 promotes the proteasome-dependent degradation of p73

The transcription factor p73, a member of the p53 family, mediates cell-cycle arrest and apoptosis in response to DNA damage-induced cellular stress, acting thus as a proapoptotic gene. Similar to p53, p73 activity is regulated by post-translational modification, including phosphorylation, acetylation and ubiquitylation. In C. elegans, the F-box protein FSN-1 controls germline apoptosis by regulating CEP-1, the single ancestral p53 family member. Here we report that FBXO45, the human ortholog of FSN-1, binds specifically to p73 triggering its proteasome-dependent degradation. Importantly, SCF(FBXO45) ubiquitylates p73 both in vivo and in vitro. Moreover, siRNA-mediated depletion of FBXO45 stabilizes p73 and concomitantly induces cell death in a p53-independent manner. All together, these results show that the orphan F-box protein FBXO45 regulates the stability of p73, highlighting a conserved pathway evolved from nematode to human by which the p53 members are regulated by an SCF-dependent mechanism

Comparaison de l'effet cryoprotecteur de differents glucides sur le sperme de truite arc en ciel (Oncorhynchus mykiss)

Author deals with the preservation of sperm of salmonidae: glucose, sugars and saccharides are studied

La croissance de la truite commune (Salmo trutta L.) sur le bassin de Scorff

La croissance de la truite commune (Salmo trutta L.) a été étudiée à partir du suivi de cinq cohortes âgées de 0 - à 2 - ans dans quatre milieux différents (Scorff aval et amont, affluent, sous-affluent). D'une manière générale, la taille destruites quelque soit leur âge diminue de l'aval vers l'amont du Scorff et de la rivière à l'affluent et au sous-affluent. Le taux mensuel de croissance G = 2,85 (LnL2 — LnL1)/(T2 — T1) diminue de la première à la troisième année de vie quelque soit l'ordre de drainage. Ce taux de croissance varie suivant le milieu pour les deux premières classes d'âge (0 + et 1 +), cet effet milieu étant relié à la densité de population pour les individus 0 +. Le taux de croissance varie également suivant les années mais uniquement chez les plus jeunes truites et cet effet année est relié principalement à la température de l'eau. Un modèle de Von Bertalanffy est proposé pour décrire la relation entre la taille (Lf) et la somme des températures moyennes journalières depuis la date moyenne d'émergence (Tmj)pendant la première année : Lf = 106,7 (1 — exp [ — 0,0005 (Tmj + 468)]). Les résultats sont discutés et permettent de dégager les faits majeurs intervenant sur la croissance de la truite tout au long d'un cycle jusqu'à la maturation sexuelle. Mots-clés : Température - Croissance - Truite commune - Rivière - France