Éditeur(s) : Springer
Résumé : Proteinases from hepatopancreas (HP) and gastric juice (GJ) from wild and cultured red octopus (Octopus maya) were characterized. Hepatopancreas assays revealed optimal activity at pH 4, 9-10 and 10 for wild and pH 3, 8, and 9, for cultured octopuses, for total proteinases, trypsin and chymotrypsin, respectively. In the gastric juice, maximum activity was recorded at pH 6, 8, and 7 for total proteinases, trypsin, and chymotrypsin, respectively for both wild and cultured octopus. A reduction on enzyme activity of 70 and 20% was observed in HP and GJ extracts, respectively when protease inhibitor Pepstatin A was used. That result suggests that the main proteases in the HP were aspartic acid proteinases type (possibly Cathepsin D) and some of them were present in the GJ. Dissociating discontinuous polyacrylamide gel electrophoresis showed activity bands between 20 and 28, 30 and 34, 35 and 45, 60 and 70 kDa, and a last one between 75 and 100 kDa. We concluded that extracellular digestion of O. maya takes place in an acid environment, around pH 6. In contrast, intracellular digestion in the HP is developed at pHs between 3 and 4, where cathepsin D could be the most important enzyme for O. maya.
Aquaculture International (0967-6120) (Springer), 2011-06 , Vol. 19 , N. 3 , P. 445-457

Droits : Springer Science+Business Media B.V. 2010
http://archimer.ifremer.fr/doc/00036/14683/17998.pdf
DOI:10.1007/s10499-010-9360-5
http://archimer.ifremer.fr/doc/00036/14683/

Éditeur(s) : Blackwell science
Résumé : A study was conducted to evaluate variations of digestive enzyme activities in Litopenaeus vannamei (Boone) reared in commercial ponds under semi-intensive conditions. Shrimp were collected at each body weight increase of 2 g. As the shrimp grew (2-12 g), significant increases in the activities of lipase and chymotrypsin were observed. The total protease activity decreased from 6 g onwards. Trypsin activity showed a peak at 6 g and amylase activity increased two-fold after 2 g. Additionally, the stomach contents were analysed microscopically for shrimp between 2 and 10 g. Plant matter contributed above 30% of the total stomach content in 6-, 8- and 10-g shrimp. Detritus represented 58% and 62% of the total stomach content in 2- and 4-g shrimp, respectively, decreasing to 33-43% at greater shrimp weights. Artificial feed showed a maximum contribution of 20% in 6-g shrimp. The present results show changes in the enzyme activity after the shrimp reach 6 g in body weight, evidenced by a decrease in total protease and an increase in lipase and amylase activities. The amylase/protease ratio was 2.6 in 2-g shrimp and increased steadily to 9.6 in 12-g shrimp. These findings suggest an adaptation of the enzymatic activity to diets with lower protein content as body weight increases, and may be related to the variation of the different items found in the stomach.
Aquaculture Research (1355-557X) (Blackwell science), 2003-12 , Vol. 34 , N. 15 , P. 1403-1411

Droits : Blackwell Publishing, Inc.
http://archimer.ifremer.fr/doc/2003/publication-902.pdf
DOI:10.1111/j.1365-2109.2003.00959.x
http://archimer.ifremer.fr/doc/00000/902/

Résumé : Bacteriological study of abyssal sediments: During the Demeraby mission of the N/O Jean Charcot in the western Atlantic Ocean, a study of the microflora of the digestive tracts of echinoderms (Holothuroidea of various genera, Asteroidea, Echinoidea) was compared with that of the surrounding sediment. The bacterial concentration observed in the digestive tracts of all the animals studied is higher than that in the surrounding sediments. The largest numbers were always found in the most anterior part of the digestive tracts of the holothurians. In some cases, the increase is considerable (7.10 versus 5.2. 10 cells per millilitre): It indicates a proliferation of bacterial cells in the anterior part of the digestive tract. As the sediment moves through the digestive tract, the bacterial level progressively decreases. In the most posterior part, the concentration is, however, always clearly greater than that in the surrounding sediment. In the case of the holothurian of the genus Deima, analysis according to the Adamsonian principle of comparison shows that the microflora isolated from the various parts of the digestive tract is composed of taxonomic groups showing little resemblance to those isolated from the sediment. In the case of the holothurian of the genus Pseudostichopus, no specialisation of the microflora from digestive tract contents appears with respect to that of the ingested sediment. Examination of metabolic activities suggests a juxtaposition of two types of communities: Free sediment - sediment in transit that complement one other in their enzymatic and nutritional behaviour Indeed, the strains of free sediment seem to be rather suitable for hydrolysing and using carbohydrates, while those of enteric communities prefer the hydrolysis of lipids and proteins and the assimilation of fatty acids, dicarboxylic acids, hydroxylic acids and certain amino acids. Moreover, the enteric microflorae possess a greater nutritional versatility that, linked with its total numbers, has a sizeable catabolic potential. .../... -2- Measurements of heterotrophic activity done by means of 14 C glucose tracers make it possible to show that the metabolic activities of the bacterial communities of superficial abyssal sediments vary according to zones. In the Amazon Cone, a clear glucose mineralization gradient over a distance of a few kilometres can be observed. In the abyssal plain of Demerara heterotrophic activities are slowed in relation to those of the superficial sediments of the Cone of the Amazon, even though the bacterial numbers and the depths are of the same order of magnitude in the two zones. The abundant microflorae associated with the various divisions of digestive tract contents of the Deima abyssal holothurian manifest little metabolic activity as regards the glucose. However, the bacterial communities of Pseudostichopus and Psychropotes manifest very strong heterotrophic activities, increasing from the oesophagus towards the cloaca. Current results are too fragmentary to allow us to observe possible physiological specialisation of enteric bacterial communities enabling the facilitation of digestion processes in the host. Conclusion: In the abyssal environment, characterised by poorly developed bacterial communities, microflorae associated with the digestive tract contents of echinoderms have considerably greater cellular concentrations. By means of their enzymatic equipment, these enteric communities, which complement those of the free microflorae of superficial sediments, can participate in the transformation of organic matter in the abyssal area. Study of the dynamics of microbial communities and their heterotrophic activities in shellfish farms: From experiments done on the water in the Arcachon basin, trials to quantify and describe the reactivity potential of bacterial communities were performed. Bacterial communities were defined by direct counts, counts after setting them up for cultivation, structure and diversity of these communities, dosage of AMP, ADP, ATP. Two opposite ecological conditions were considered: Autumn conditions (high temperature) and a winter conditions (low temperature). Tubs of sea water of 6 and 60 litres were enriched either with ammonium chloride or a mixture of amino acids, at about 500 uAtg N.L. The experiments lasted 24 hours, with sampling every 3 hours. The autumn community reacted rapidly (6 hours), the response to the enrichment in organic nitrogen being the highest. The structure of the community has unstable immature stages. On the contrary, during the winter experiment, no response could be perceived. This may mean that the latency phase is greater than 24 hours. The structure of this community has mature stages. In conclusion, bacterial communities react in the same way as macroscopic communities. Stable communities are diversified and correspond to mature stages of the ecosystem; the immature stages are unstable and less diversified. This type of experiment has made it possible to bring to light the rapidity of response of bacterial populations, and can be used to define the stability of a bacterial community in a precise biotope.
ETUDE BACTERIOLOGIQUE DES SEDIMENTS ABYSSAUX RESUME Au cours de la mission DEMERABY du n/o Jean CHARCOT en atlantique occidental , une étude de la microflore des tractus digestifs d'Echinodermes (Holothurides de différents genres, Astérides, Echinides) a été comparée à celle du sédiment environnant. La concentration bactérienne observée dans les tractus digestifs de tous les animaux étudiés est supérieure à celle des sédiments environnants. Les effectifs les plus importants sont toujours observés dans la partie la plus antérieure des tractus digestifs des holothuries. Dans certains cas, l'accroissement est considérable (7.10 contre 5,2. 10 cellules/ml) : il indique une prolifération des cellules bactériennes dans la partie antérieure du tractus digestif. Au.cours de la progression du sédiment dans le tractus digestif, la charge bactérienne décroit progressivement. Dans la partie la plus postérieure, la concentration est cependant toujours nettement supérieure à celle du sédiment environnant-. Dans le cas d'une holothurie du genre Deima, l'analyse selon le principe adansonien de comparaison montre que la microflore isolée des différentes parties du tractus digestif est constituée de groupes taxonomiques présentant peu de ressemblance avec ceux isolés du sédiment. Dans le cas d'une holothurie du genre Pseudostichopus il n'apparait pas de spécialisation de la microflore du contenu du tractus digestif par rapport à celle du sédiment ingéré. ¿ ¿ . L'étude des activités métaboliques suggère une juxtaposition de deux types de communautés : sédiment libre-sédiment en transit qui se complètent dans leur comportement enzymatique et nutritionnel. En effet les souches du sédiment libre semblent être plutôt aptes à hydrolyser et à utiliser les glucides, tandis que celles des communautés entériques portent leur préférence sur l'hydrolyse des lipides et protéines et 1'assimilation des acides gras, acides dicarboxyl iques, hydro'xy-acides et certains acides aminés. D'autre part les microflores entériques possèdent une versatilité nutritionnelle plus importante qui, liée à leurs effectifs, offre une potentialité catabolique non négligeable. .../... -2- Les mesures d'activité hétérotrophe effectuées au moyen de traceurs glucose 14 C permettent de montrer que les activités métaboliques des communautés bactériennes des sédiments abyssaux superficiels varient selon les zones. Dans le Cone de l'Amazone on observe un net gradient de minéralisation du glucose sur une distance de quelques kilomètres. Dans la plaine abyssale de Demerara les activités hétérotrophessont ralenties par rapport à celles des sédiments superficiels du Cone de l'Amazone, bien que les effectifs bactériens et les profondeurs soient du même ordre de grandeur dans ces deux zones. Les abondantes microflores associées aux différentes fractions du contenu du tractus digestif de l'holothurie abyssale Deima ne manifestent que peu d'activités métaboliques vis à vis du glucose. Par contre les communautés . bactériennes de Pseudostichopus et P syahropotes manifestent des activités hétérotrophes très fortes, croissant de 1'oesophage vers le cloaque. Les résultats actuels sont trop fragmentaires pour permettre d'observer une éventuelle spécialisation physiologique des communautés bactériennes entëriques permettant de faciliter les processus de digestion chez l'hôte. Conclusion: dans le milieu abyssal, caractérisé par des communautés bactériennes faiblement développées, les microflores associées aux contenus de tractus digestif des Echinodermes présentent des concentrations cellulaires considérablement plus importantes. Par leurs équipements enzymâtiques ces communautés entëriques complémentaires de ceux des microflores libres des sédiments superficiels, peuvent participer à la transformation des matières organiques du domaine abyssal. ETUDE DE LA DYNAMIQUE DES COMMUNAUTES MICROBIENNES ET DE LEURS ACTIVITES HETEROTROPHES DANS LES PARCS CONCHYLICOLES RESUME A partir d'expérimentations effectuées sur l'eau du bassin d'Arcachon, des essais de quantification et qualification du potentiel de réactivité des communautés bactériennes ont été effectuées. Les communautés bactériennes ont été définies par comptage directs, comptages après mise en culture, structure et diversité de ces communautés, dosage des AMP, ADP, ATP. Deux situations écologiques opposées ont étées considérées . Une situation automnale (température élevée) et une situation hivernale (température faible). Des bacs d'eau de mer de 6 et 60 litres ont été enrichis , soit avec du chlorure d'ammonium, soit avec un mélange d'acides aminés, à environ 500 uAtg N.l" . Les expériences ont duré 24 heures, avec des prélèvements toutes les 3 heures. La communauté automnale réagit rapidement (6 heures), la ' réponse à l'enrichissement en azote organique étant la plus importante. La structure de la communauté présente des stades immatures instables. Au contraire, au cours de l'expérimentation hivernale, aucune réponse n'a pu être perçue. Ceci peut signifier que la phase de latence est supérieure à 24 heures. La structure . de cette communauté présente des stades matures. En Conclusion, les communautés bactériennes réagissent de la même façon que les communautés macroscopiques. Les communautés stables sont diversifiées et correspondent à des stades matures de l'écosystème, les stades immatures sont instables et moins diversifiés. Ce type d'expérience a permi de mettre en évidence la rapidité de réponse des populations bactériennes, et peut être utilisé pour définir la stabilité d'une communauté bactérienne dans un biotope précis.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1981/rapport-1926.pdf
http://archimer.ifremer.fr/doc/00000/1926/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Strombus gigas and Strombus pugilis are threatened species and aquaculture represents a good alternative solution to the fishing. In this study, we highlighted the intracellular digestion process in the digestive gland of two Strombidae species, S. gigas and Strombus pugilis, by the cytochemical characterization of two lysosomal enzymes: acid phosphatase and arylsulfatase. In order to check the efficiency of artificial food digestion, we onducted the characterization on freshly collected, tarved and artificially fed individuals of S. pugilis. TEM observations of digestive gland sections from freshly collected individuals of both species revealed the resence of acid phosphatase and arylsulfatase activity mostly located in the apical third of digestive cells. Both enzymes were also detected in artificially fed individuals. In response to the starvation, acid phosphatase is not produced anymore by digestive cells, while arylsulfatase is still present. To our knowledge, this is the first cytochemical validation of intracellular digestion of artificial food in Strombidae. This study highlights the intracellular digestion of artificial food developed for Strombidae aquaculture. Moreover, we have shown that the lysosomal activity could be used as a feed index.
ISSN: 1059-910X

hal-00743013
https://hal.univ-antilles.fr/hal-00743013
DOI : 10.1002/jemt.22074

Éditeur(s) : Elsevier
Résumé : Marine fish larvae undergo major morphological and cellular changes during the first month of life. The ontogeny of the gastrointestinal tract combines these two aspects of the larval development and is very interesting in that the timing of functional changes appears genetically hard-wired. The goal of this paper is to give an overview of the gastrointestinal development process in marine fish larvae, with particular attention to three species: sea bass; red drum; and sole, since the description of gut maturation in fish larvae was initiated during the last decade with these species. During the early stages, marine fish larvae exhibit particular digestive features. Concerning the exocrine pancreas, amylase expression decreases with age from the third week post-hatching in sea bass and red drum (approximately 400 degree days), whereas expression of other enzymes (trypsin, lipase, phospholipase A2...) increases until the end of the larva period. Moreover, secretory function of the exocrine pancreas progressively develops and becomes efficient after the third week of life. Concerning the intestine, enzymes of the enterocyte cytosol (in particular peptidase) have higher activity in young larvae than in older. Approximately in the fourth week of post-hatching development in sea bass, red drum and sole larvae, the cytosolic activities dramatically decline concurrently with a sharp increase in membranous enzyme activities of the brush border, such as alkaline phosphatase, aminopeptidase N, maltase... This process characterises the normal maturation of enterocytes in developing fish larvae and also in other vertebrates' species. The establishment of an efficient brush border membrane digestion represents the adult mode of digestion of enterocytes. This paper also describes the role of diet on the development of the gastrointestinal tract. Indeed, the maturational process of digestive enzyme can be enhanced, stopped, or delayed depending on the composition of the diet.
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology (1532-0456) (Elsevier), 2001-12 , Vol. 130 , N. 4 , P. 477-487

Droits : 2001 Elsevier Science Inc. All rights reserved
http://archimer.ifremer.fr/doc/2001/publication-650.pdf
DOI:10.1016/S1532-0456(01)00274-5
http://archimer.ifremer.fr/doc/00000/650/

Éditeur(s) : Elsevier
Résumé : Until recently, it was considered impossible to feed newly hatched marine fish species with a compound diet. Substituting a compound diet for live prey was performed several weeks after hatching, depending on the species. Compound diets were well ingested at the early stage but larvae died with a gut full of food, suggesting that larvae were unable to digest the compound diet. The hypothesis was that younger larvae have insufficient digestive enzymes to thrive on compound diets, and that exogenous enzymes, provided from live prey, are necessary for early stages.The organogenesis of marine fish larvae is not completely achieved at hatching and histological studies have revealed that the anatomy of the digestive tract undergoes developmental changes over some weeks. Nevertheless, biochemical studies over 20 years have shown that most of the digestive enzymes are present in young larvae. Recent studies have provided better understanding of digestion mechanisms in larvae and have led to proposed dietary compositions meeting larvae nutritional requirements. Pancreatic digestive enzymes are detected before mouth opening. Their synthesis is not induced by diet ingestion, but secretory mechanisms in the pancreas, and so enzymatic action, become efficient chronologically after those of synthesis. Inadequate diets can delay the onset of secretion mechanisms. The ratio of secreted enzymes to total enzymes indicates the nutritional value of the diet ingested by the larvae.At the intestinal level, cytosolic enzymes, which are peptidases, exhibit high activity in the early stages, suggesting a high capacity in larvae to digest protein hydrolysate. Indeed, larvae growth and survival is improved by the incorporation of a moderate concentration of peptide or hydrolysate in the diet. Peptidase activity abruptly decreases around day 25 in sea bass, concurrent with an increase in enzymes of the brush border membranes. This corresponds to a normal maturation process of enterocytes. Compound diets can slightly delay the onset of this maturation process, and inadequate diet can prevent it, leading to near death of the larvae. A proper onset of the maturation process has been associated with high larvae survival.The early developmental stage larvae exhibit high hydrolytic capacity, related to their weight. Enzyme activity pattern is age-dependent, but can be modulated by diet composition. Thus, larvae have the ability to digest and thrive on compound diet, if this diet is well adapted. Larvae have different specificities in digestion and nutritional requirements when compared to juveniles. Taking these specificities into consideration, recent research has led to the formulation of a compound diet that was well adapted for larvae from mouth opening, and could totally replace live prey.
Aquaculture (0044-8486) (Elsevier), 2001-08 , Vol. 200 , N. 1-2 , P. 161-180

Droits : 2001 Elsevier Science B.V. All rights reserved
http://archimer.ifremer.fr/doc/2001/publication-447.pdf
DOI:10.1016/S0044-8486(01)00699-8
http://archimer.ifremer.fr/doc/00000/447/

Éditeur(s) : Elsevier
Résumé : Red drum larvae were fed from day 11 to day 24 post-hatch, with Artemia (LP group) or two isoproteinic-formulated diets with varying lipid levels, 15% (L15 group) and 30% (L30 group). The lipid fraction was composed of a mixture of cod liver oil and soy lecithin. Larvae fed Artemia exhibited the greatest length, L30 diet induced a larvae length significantly greater than that obtained with L15 diet (P < 0,05). No difference was observed in larvae survival among the three dietary groups. The increase in dietary lipid concentration led to an increase in amylase and trypsin secretion levels in 24-day-old larvae. The pancreatic secretion level measured in L30 group was close to that of LP group, suggesting that the maturation of the pancreatic functions was normally developed. Red drum larvae fed the diet containing the higher lipid content (L30) exhibited a more developed brush border membrane digestion in the intestine than larvae fed L15 diet (P < 0.05). Phospholipase A2 was stimulated by the increase of phospholipids in the diet, but no difference was observed for lipase between the two compound diet-fed groups; the LP group exhibited the lowest lipase activity. A plateau in lipase activity may have occurred in red drum larvae from 15% fat level in the diet, suggesting that the maximal lipase activity was reached with 12% neutral lipid in the diet. The positive effects observed with high dietary fat may be due to the phospholipid fraction of the lipid mixture used.
Aquaculture (0044-8486) (Elsevier), 2000-04 , Vol. 184 , N. 3-4 , P. 339-347

Droits : 2000 Elsevier
http://archimer.ifremer.fr/doc/2000/publication-503.pdf
DOI:10.1016/S0044-8486(99)00325-7
http://archimer.ifremer.fr/doc/00000/503/

Résumé : This report is presented by Chantal Cahu for obtaining accreditation to supervise research. Since 1981, her research activity has addressed the study of reproducers' nutrition and the young stages of development of marine organisms belonging to two different branch lines, crustaceans and fish. This work, performed in a base-lined research body, IFREMER, is placed within a more general programme of aquaculture development. Indeed, whatever species are at issue, the development of aquaculture in France, as at the global level, is based on the production of juveniles in hatcheries. My work has therefore more precisely the goal of acquiring knowledge about the nutritional needs, mechanisms of digestion and the development of these animals in order to improve the production of prawn post-larvae and fish alevin in the hatchery. This work took place in three main periods that appear in this report: - The study of reproducers' nutrition and its influence on the quality of the Penaeid prawn's eggs and larvae. My work has focused mainly on the effect of lipids and vitamins on the development of eggs and larvae. - The study of the ontogenesis of the digestive functions and the nutritional needs of sea fish larvae, with bass as the model. The goal was to determine the specific nutritional needs of the young stages by studying the implementation and regulation of pancreatic and intestinal digestive enzymes. - The study of the regulation of certain developmental genes by means of nutrients, so as to understand how these nutrients behave during ontogenesis, particularly during development of the skeleton.
Ce mémoire est présentée par Chantal Cahu pour pour l'obtention d'une habilitation a diriger des recherches. Depuis 1981, son activité de recherche concerne l'étude de la nutrition des reproducteurs et des jeunes stades de développement d'organismes marins appartenant à deux embranchements différents, les crustacés et les poissons. Ce travail réalisé dans un organisme de recherche finalisée, l'Ifremer, se situe dans un programme plus général de développement de l'aquaculture. En effet, quelles que soient les espèces en jeu, le développement de l'aquaculture en France comme au niveau mondial repose sur la production de juvéniles en écloserie. Mon travail a donc plus précisément pour objectif l'acquisition de connaissances sur les besoins nutritionnels, les mécanismes de digestion et le développement des ces animaux afin d'améliorer la production de post-larves de crevettes et d'alevins de poissons en écloserie. Ce travail s'est déroulé en trois grandes périodes qui apparaissent dans ce mémoire : - L'étude de la nutrition des reproducteurs et son influence sur la qualité des oeufs et des larves de crevettes Pénéides. Mon travail a essentiellement porté sur l'effet des lipides et des vitamines sur le développement des oeufs et des larves. - L'étude de l'ontogenèse des fonctions digestives et les besoins nutritionnels des larves de poissons marins, avec le bar comme modèle. Le but était de déterminer les besoins nutritionnels spécifiques des jeunes stades, en étudiant la mise en place et la régulation des enzymes digestives pancréatiques et intestinales. - L'étude de la régulation de certains gènes du développement par les nutriments, de façon à comprendre comment ces nutriments agissent lors de l'ontogenèse, notamment lors du développement du squelette.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/rapport-2086.pdf
http://archimer.ifremer.fr/doc/00000/2086/

Éditeur(s) : Co-tutelle Al Centro de Investigaciones Biológicas del Noroeste - Université de Bretagne occidentale
Résumé : The interest in probiotics for aquaculture is increasing rapidly. In the present work we evaluated the potential of some yeast to induce the larvae gut maturation in sea bass larvae Dicentrarchus labrax. The production of polyamines putrescine, spermidine and spermine was quantified in ten yeast strains using high performance liquid chromatography (HPLC). Afterwards, fluorescently labelled yeast adhesion to the intestine of sea bass larvae and the spotted sand bass (Paralabrax maculatofasciatus) was evaluated by fluorescent microscopy. Two of them, CBS 8339 strain (Debaryomyces hansenii) and X2180 strain (Saccharomyces cerevisiae) produce the polyamines of our interest. The same strains showed the best adhering capabilities to the sea bass and spotted sand bass intestine. Both strains were selected and introduced by pulverization into the diet of larvae. The larvae fed with CBS 8339 strain, increase survival in 8.3% but not in their weight. The secretion of trypsin and amylase as well as those from the brush border membrane: alkaline phosphatase, maltase and leucine aminopeptidase, are incresed at 27 days after hatching (dah). At 42 dah difference in the enzyme activity of the different groups does not exist, suggesting a maturation of the digestive system in early stages of larval development. A second experiment was carried out to know the effect of different levels of incorporation into the diet of CBS 8339 strain: 1.1% and 5.7%. The minimum level, 1.1% of yeast produce best growth and survival rates, as well as lower deformed larvae than those obtained by 5.7% and the control one. Both level of yeast inclusion favored the trypsin secretion and lipase activity at 26 dah. Whereas mRNA levels for trypsin and amylase were influenced by both yeast concentrations at 26 and 36 dah, which suggest a development of digestive capacity of larvae as a result of the presence of polyamines secreted by the yeast.
Les probiotiques ont été définis comme des préparations microbiennes vivantes utilisées comme additif alimentaire, et qui ont une action bénéfique sur l'animal hôte en améliorant la digestion et l'hygiène intestinale. L'application de tels traitements aux productions aquacoles suscite un intérêt qui s'accroît rapidement. Dans ce travail, nous avons étudié l'effet de souches de levures sur la maturation de l'intestin des larves du bar Dicentrarchus labrax. Ces souches produisent des polyamines qui sont impliquées dans la réplication et la différentiation cellulaire, ainsi que dans la synthèse des protéines et des acides nucléiques. Dix souches de levures ont été testées pour leur production de polyamines (putrescine, spermidine et spermine), et pour leur adhérence à la paroi intestinale du bar et la cabrilla (Paralabrax maculatofasciatus). La production des polyamines a été analysée en utilisant la chromatographie liquide à haute performance (HPLC). Les levures selectionées ont été marquées avec un composé fluorescent pour tester leur adhérence a l'intestin de larves de bar et de juvéniles de cabrilla. L'adhérence a pu ainsi être evaluée par observation microscopique en épifluorescence. Les souches CBS 8339 (Debaryomyces hansenii) et X2180 (Saccharomyces cerevisiae) ont été choisies pour leur forte production de spermidine et de spermine, respectivement, et pour leur capacité d'adhérence à l'intestin du bar et de la cabrilla. Les deux souches ont été ajoutées par pulvérisation au régime des larves. Nous avons observé une augmentation de 8.3% du taux de survie avec les larves alimentées avec la souche CBS 8339, mais le poids moyen de ces larves était inférieur à celui obtenu sans ajout de levure. Une augmentation de l'activité de la trypsine et de l'amylase, aussi bien que des activités enzymatiques dans la bordure en brosse, aminopeptidase, phosphatase alkaline et maltase, ont été observées dans les larves âgées de 27 jours alimentées avec la souche CBS 8339. Au jour 42, il n'existait plus de différence d'activité enzymatique entre les larves traitées ou non avec la levure. Ces résultats suggèrent que la maturation du système digestif a été accélérée chez les larves nourries avec la levure, la maturation étant achevée chez les larves de 42 jours, qu'elles aient reçu l'un ou l'autre régime. Une deuxième expérience a été effectuée pour étudier l'effet de différents niveaux d'incorporation dans le régime contenant 1,1% et 5,7% de levure CBS 8339. L'incorporation de 1,1% a induit une augmentation du poids moyen et du taux de survie des larves, ainsi qu'une réduction du taux de malformation de la colonne vertébrale, par rapport aux résultats obtenus avec 0 ou 5,7% de levure. Les deux niveaux d'incorporation de la levure ont favorisé l'activité de la trypsine et de la lipase au jour 26. Les niveaux d'ARNm codant pour la synthèse de la trypsine et de l'amylase ont été influencés par les deux doses de levure aux jours 26 et 36. Ces résultats suggèrent qu'une faible dose de levure améliore le développement et la capacité digestive des larves, et nous formulons l'hypothèse que cette efficacité est due à la production de polyamines in situ. Le rôle des polyamines est particulièrement important pendant les phases de forte croissance comme les stades larvaires, mais elles peuvent être toxiques à dose trop élevée. L'incorporation de levure dans l'aliment destiné aux larves semble donc une excellente méthode pour délivrer les polyamines chez l'animal hôte.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2002/these-103.pdf
http://archimer.ifremer.fr/doc/00000/103/

Éditeur(s) : HAL CCSD American Society for Biochemistry and Molecular Biology
Résumé : International audience
The budding yeast Saccharomyces cerevisiae is a major model organism for important biological processes such as mitotic growth and meiotic development, it can be a human pathogen, and it is widely used in the food-, and biotechnology industries. Consequently, the genomes of numerous strains have been sequenced and a very large amount of RNA profiling data is available. Moreover, it has recently become possible to quantitatively analyze the entire yeast proteome; however, efficient and cost-effective high-throughput protein profiling remains a challenge. We report here a new approach to direct and label-free large-scale yeast protein identification using a tandem buffer system for protein extraction, two-step protein prefractionation and enzymatic digestion, and detection of peptides by iterative mass spectrometry. Our profiling study of diploid cells undergoing rapid mitotic growth identified 86% of the known proteins and its output was found to be widely concordant with genome-wide mRNA concentrations and DNA variations between yeast strains. This paves the way for comprehensive and straightforward yeast proteome profiling across a wide variety of experimental conditions.
ISSN: 1535-9476

hal-00682837
https://hal.archives-ouvertes.fr/hal-00682837
DOI : 10.1074/mcp.M111.012682
PUBMED : 21997732

Éditeur(s) : Elsevier
Résumé : in this study we evaluated the effects of the probiotic Pediococcus acidilactici MA18/5M on shrimp, Litopenaeus stylirostris (also called Penaeus stylirostris), first on antioxidant defences and secondly on the oxidative stress status in the shrimps' haemolymph and digestive gland. We conducted two experiments with the same protocol in which shrimps were fed two diets for three weeks: a control diet and a probiotic diet containing 1 g of live P. acidilactici MA18/5M kg(-1). In the first experiment, the shrimps were found to be healthy over the trial period; no mortalities and non-detectable signs of infection were recorded. These resulted in high final survival rates (above 90% in both treatments). On the other hand, during the second trial, carried out at a period of increased risk for an outbreak of the summer syndrome, higher mortalities were recorded, associated with high V. nigripulchritudo prevalence and loads in the shrimp haemolymph. In healthy shrimps (trial 1), no detectable response of the antioxidant defence system and of oxidative stress bio-indicators were observed. However, feeding the probiotic significantly increased the total antioxidant status (TAS) and glutathione peroxidase activity, while all other parameters remained significantly unchanged. In the shrimps exposed to V nigripulchritudo (trial 2), the antioxidant response was characterized by higher antioxidant enzyme activities (superoxide dismutase and catalase) and higher oxidative stress level in the digestive gland (higher oxidized/reduced glutathione ratio, higher malonclialdehyde and carbonyl protein contents) compared to levels found in trial 1. However, shrimps fed the probiotic diet exhibited (i) significantly higher final survival rates (67 +/- 3%) compared to the control (47 +/- 4%) and (ii) a lower prevalence of V nigripulchritudo throughout the trial. Moreover, the antioxidant response and the oxidative stress level recorded in the digestive gland with shrimps submitted to the probiotic diet were lower. In the light of these results, we confirm that P acidilactici enrichment in shrimps' diet seems an effective way of reducing the susceptibility of shrimps to bacterial pathogens. (c) 2009 Elsevier B.V. All rights reserved.
Aquaculture (0044-8486) (Elsevier), 2009-09 , Vol. 294 , N. 3-4 , P. 306-313

Droits : 2009 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/2009/publication-6780.pdf
DOI:10.1016/j.aquaculture.2009.06.016
http://archimer.ifremer.fr/doc/00000/6780/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The Caribbean bivalves Codakia orbicularis (Linnée, 1758) and C. orbiculata (Montagu, 1808) live in seagrass beds of Thalassia testudinum and harbor intracellular sulfuroxidizing gamma-proteobacteria. These bacterial symbionts fix CO2 via the Calvin Benson cycle and provide organic compounds to the bivalve. During experimentally induced starvation, no reduced sulfur compounds and no organic particle food are available; the symbionts could be considered as the sole nutrient source of the host bivalve. A previous study has shown that the intracellular bacterial population decreased considerably during starvation and that bacterial endosymbionts were not released by the bivalves. In this study, the activity of two lysosomal marker enzymes (acid phosphatase and arylsulfatase) was detected using cytochemical experiments coupled with energy-dispersive X-ray transmission electron microscopy during sulfide and organic particle starvation. The degradation of bacterial endosymbionts began after 2 weeks of starvation in C. orbiculata and after 3 weeks in C. orbicularis. Degradation processes seem to be continuous over several months and could be responsible for the disappearance of the bacterial endosymbionts within the gills during starvation. These data suggest that the host use symbionts as a nutrient source to survive a hunger crisis. The carbon transfer from the symbionts to the host could be flexible and could consist in transfer of organic matter, “milking,” under normal feeding conditions and digestion of the symbionts under starved conditions.
ISSN: 1059-910X

Droits : info:eu-repo/semantics/OpenAccess
hal-01206367
https://hal.univ-antilles.fr/hal-01206367
https://hal.univ-antilles.fr/hal-01206367/document
https://hal.univ-antilles.fr/hal-01206367/file/revised%20version%20to%20be%20submitted%20to%20the%20editor3oct.pdf
DOI : 10.1002/jemt.22458