Activities of selected digestive enzymes during larval development of large yellow croaker (Pseudosciaena crocea)

International audienceLarge yellow croaker is an important marine fish species for aquaculture in China. Larval rearing of this species is still based on live prey feeding. The aim of this study was to describe the onset and development of the main digestive enzymes during larval development of this species, in order to obtain essential data for the formulation of a compound diet adapted to larvae. Enzymatic assays were conducted from day I post hatching to day 40 in larvae fed the following live prey sequence: rotifers, Artemia nauplii, copepods, and then frozen copepods. Assays were done on whole larvae until day 19, then on dissected larvae and on purified brush border membranes of intestine. Pancreatic enzymes, amylase, and trypsin, showed high activities from early stages, even before mouth opening. Mechanisms of pancreatic secretion were achieved from day 19. Enzymes of brush border membranes, alkaline phosphatase, and aminopeptidase N, increased abruptly between day 23 and 25, showing maturation of the intestinal digestive process. These data, together with data describing mouth enlargement during development, suggest that large yellow croaker larvae could be fed successfully with a compound diet from early stages, at least from day 23

The effects of dietary marine protein hydrolysates on the development of sea bass larvae, Dicentrarchus labrax, and associated microbiota

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Gene expression pattern of digestive and antioxidant enzymes during the larval development of reared Atlantic bluefin tuna (ABFT), Thunnus thynnus L.

The aim of this study was to determine whether mortality observed during the larval development of reared bluefin tuna (Thunnus thynnus) could be related to improper expression profiles of key genes involved in digestive or antioxidant response capabilities. Tuna larvae were sampled at hatching, 2, 5, 10, 15 and 20 dph (days post hatching) for the relative quantification of transcripts encoded by genes involved in digestive [trypsinogen 1 (TRYP1), alpha-amylase (AMY), aminopeptidase N (ANPEP)] and antioxidant [catalase (CAT)] functions. The levels of expression of ANPEP related to the development and maturation of intestinal function increased from 5 to 20 dph. Furthermore, AMY and TRYP1 genes, which are pancreatic enzymes implicated in carbohydrate and peptide digestions exhibit a typical peak of expression at 5 and 15 dph respectively. The antioxidant enzyme, CAT, exhibited higher mRNA levels during the first stage of larval development. In conclusion, our investigation indicates that the expression of genes involved in digestive and antioxidant physiological processes followed typical patterns which could not explain high mortality rate observed during the first stage of larval development

Imbalanced dietary ascorbic acid alters molecular pathways involved in skeletogenesis of developing European sea bass (Dicentrarchus labrax)

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Contribution à la lecture des paléoclimats quaternaires d'après les données de la Paléontologie en milieu continental.

Les auteurs considèrent l'importance relative de trois groupes d'Ongulés au sein des associations fauniques du Pléistocène supérieur les mieux connues jusqu'ici en Aquitaine. Groupe de Milieu Ouvert Arctique (Renne souvent accompagné dans la région du Bouquetin et du Chamois) ; Groupe de Milieu Ouvert non Arctique (Antilope saïga, Cheval, Bison des steppes, Boeuf primitif) ; Groupe de Milieu Boisé (Cerf, Chevreuil, Sanglier). La prédominance d'un de ces groupes a une signification déterminée qui s'accorde en général très bien avec les données de la palynologie, mais il est également significatif qu'un des trois ensembles ne prenne pas l'avantage (période de transition).The authors consider the relative importance of three groups of Ungulates within faunal associations of Upper Pleistocene the best known up to here in Aquitaine. Group of Environment Opened Arctic (Reindeer often accompanied in Aquitaine of the Ibex and the Chamois); group of Environment Opened not Arctic (Antelope saiga, Horse, Bison of steppes, primitive Ox); group of Wooded Environment (Deer, Roe deer, Wild boar). The ascendancy of one of these groups has a definite meaning which agrees generally very well with the data of the Palynology, but it is also significant that one of three groups does not take the advantage (period of transition)

Dietary vitamin mix levels influence the ossification process in European sea bass ( Dicentrarchus labrax ) larvae

International audienceThe influence of dietary vitamins on growth, survival, and morphogenesis was evaluated until day 38 of posthatching life in European sea bass larvae ( Dicentrarchus labrax). A standard vitamin mix (VM), at double the concentration of the U.S. National Research Council's recommendations, was incorporated into larval feeds at 0.5%, 1.5%, 2.5%, 4.0%, and 8.0% to give treatments VM 0.5, VM 1.5, VM 2.5, VM 4.0, and VM 8.0, respectively. The group fed the VM 0.5 diet all died before day 30. At day 38, the larvae group fed VM 1.5 had 33% survival, while the other groups, with higher vitamin levels, showed at least 50% survival. The higher the percentage VM in the diet, the lower the percentage of column deformities. High dietary vitamin levels positively influenced the formation of mineralized bone in larvae: the higher the dietary vitamin level, the higher the ossification status. In the larvae group fed at the highest vitamin levels, we observed a temporal sequence of coordinated growth factor expression, in which the expression of bone morphometric protein (BMP-4) preceded the expression of IGF-1, which stimulated the maturation of osteoblasts (revealed by high osteocalcin expression levels). In groups fed lower proportions of vitamins, elevated proliferator peroxisome-activated receptors (PPAR-γ) expression coincided with low BMP-4 expression. Our results suggest that high levels of PPAR-γ transcripts in larvae-fed diets with a low VM content converted some osteoblasts into adipocytes during the first two weeks of life. This loss of osteoblasts is likely to have caused skeletal deformities

Impacts of Long-Term Exposure to Ocean Acidification and Warming on Three-Spined Stickleback (Gasterosteus aculeatus) Growth and Reproduction

The warming and acidification of surface waters as predicted by the IPCC leads aquatic species to face major multifaceted changes in their environment. Although teleosts have efficient regulatory systems to cope with these changes, such changes clearly have the potential to impact their physiological functions. Hence, it is crucial to estimate the ability of teleost fishes to cope with multi-stresses to predict how they will deal with future environments. In this context, we investigated the joint effect of warming and acidification on three-spined stickleback (Gasterosteus aculeatus) from the juvenile stage to adulthood, focusing on parameters linked to growth, sexual maturation, and reproduction. Juvenile sticklebacks were split in 2 climate scenarios: a “Current” scenario corresponding to the current seasonal physico-chemical parameters of the water of the “Rade de Brest” in France, and a “RCP8.5” scenario with a warming of 3 °C and an acidification of 0.4 pH units. After 7 months, fish in the RCP8.5 scenario reached the same size and mass as those in the Current scenario, but they needed greater amounts of food to reach satiety. Furthermore, the mortality rate over the experiment was higher in the RCP8.5 scenario. Muscle lipid content, an indicator of energy reserves, was lower in females in the RCP8.5 scenario, suggesting an increased need for energy to maintain homeostasis and other physiological functions or a divergence in energy allocation strategy. Moreover, females exhibited lower sexual maturation and egg quality under the RCP8.5 scenario, which could have contributed to the lower fertilisation rate observed. Males were more resilient to the RCP8.5 scenario, exhibiting only a trend for lower kidney somatic index scores. Altogether, these results suggest a delay and/or an inhibition of gametogenesis and maturation in fish in warmed and acidified waters. The analysis of blood sex steroid concentrations, brain gene expression profiles, and physiological indexes did not allow us to discriminate between a delay and an inhibition of maturation in the RCP8.5 scenario. Overall, these findings clearly indicate that there is a long-term global impact of combined acidification and warming on the mortality and reproductive performance of three-spined stickleback

Les costumes régionaux

Progressivement rejetés de la culture des élites, au XXe siècle, pour n'être plus que des objets de divertissement folklorique, les costumes régionaux de l'ère contemporaine sont pourtant d'extraordinaires documents qui autorisent une entrée dans les cultures provinciales des deux derniers siècles, faisant apparaître ce que l'archive écrite, bien souvent, ignore. S'ils sont, dans la conscience collective, de bons marqueurs des espaces régionaux, leur dimension historique a été effacée, jusqu'à créer des images intemporelles prêtes à servir les tenants d'un « ordre éternel des champs ». Or ils n'ont cessé d'évoluer dans le temps, empruntant aux circuits économiques, épousant les attentes culturelles de ceux qui les portaient, marquant les distinctions sociales, puisque, la plupart du temps, ils étaient trop coûteux pour vêtir les plus humbles. Le défi relevé par les chercheurs qui ont contribué à cet ouvrage est de restituer aux costumes régionaux leur valeur de document historique. Cela suppose de les comparer à d'autres pratiques vestimentaires, de France ou d'ailleurs, de comprendre que les multiples récupérations dont ils ont fait l'objet doivent être identifiées, ou que les tris effectués parmi eux, n'ayant visé depuis longtemps qu'à la conservation des plus spectaculaires, ont déformé notre vision de leur passé. Nous devons aujourd'hui nous pencher sur les sources et produire aussi une histoire des regards portés sur les costumes régionaux, à la fois inséparable et distincte de celle qui concerne les costumes eux-mêmes. Fruit d'un travail pluridisciplinaire et international, l'ouvrage prend appui sur les développements les plus récents de la recherche menée au CNRS, dans les musées ou les universités. Ils conduisent à la formulation de questionnements nouveaux autour des costumes régionaux qui sont, pleinement, des objets d'histoire