Diferenciación genética de poblaciones atlánticas de charcos de marea del copépodo intermareal Tigriopus brevicornis

The Harpacticoid copepod Tigriopus brevicornis belongs to the meiofauna of intertidal rock pools and is distributed widely along European coasts. Sixteen sites were sampled from the Irish Sea to the coasts of Spain. We used the ITS1 marker to analyse the relationship between the populations because it shows low intrapopulational variation (mean pairwise difference: 1.00 ± 0.8) and high interpopulational divergence (mean pairwise difference: 16.38 ± 7.39). A total of 57 bp out of 433 bp were recognised as informative nucleotides among the 61 individuals analysed. The analysis of the genetic relationships highlighted a north-south split in the distribution of the natural populations and showed a genetic break point around the Gironde estuary, which is probably due to differences in the geomorphologic characteristics of the coastal area on the two different sides of this estuary. Various populations were isolated and the ITS1 sequences indicated that there are specific genetic signatures in these populations. The northern set of populations, which was sampled along a large rocky coastline, had a metapopulation structure with genetic exchanges between geographically close populations and also between geographically far ones. The southern set of populations, which was sampled in small rocky pools on large sandy beaches, showed isolated populations as a consequence of the geomorphology of the area.Los copépodos harpacticoides Tigriopus brevicornis pertenecen a la meiofauna intermareal y están ampliamente distribuídos a lo largo de las costas europeas. Dieciséis lugares fueron muestreados desde el Mar de Irlanda hasta las costas de España. Nosotros usamos el marcador ITSI para analizar la relación entre poblaciones porque se mostró una variación interpoblacional baja (promedio diferencia de pares: 1.00 ± 0.8) y una divergencia interpoblacional alta (promedio diferencia de pares: 16.38 ± 7.39). Un total de 57 bp entre 433 bp fueron reconocidos como nucleótidos informativos entre los 61 individuos analizados. El análisis de relación genética resalta una partición Norte-Sur en la distribución de las poblaciones naturales y mostraba un punto de rotura genético alrededor del estuario de Gironde, probablemente debido a las diferencias en las características geomorfológicas de esta área costera en ambos lados del estuario. Algunas poblaciones fueron aisladas: las secuencias ITSI indicaban que había unas señales genéticas específicas en estas poblaciones. La población de la parte norte, que fue muestreada a lo largo de una línea rocosa de costa, evidencia la estructura de una metapoblación con intercambios genéticos entre poblaciones geográficamente próximas, pero también entre poblaciones geográficamente lejanas. La población de la parte sur, que fue muestreada en pequeños charcos de marea sobre vastas playas arenosas, mostraban poblaciones aisladas, destacando las consecuencias de la geomorfología del área

Effect of hyperosmotic shock on phosphoenolpyruvate carboxykinase gene expression and gluconeogenic activity in the crab muscle

AbstractChasmagnathus granulata phosphoenolpyruvate carboxykinase (PEPCK) cDNA from jaw muscle was cloned and sequenced, showing a specific domain to bind phosphoenolpyruvate in addition to the kinase-1 and kinase-2 motifs to bind guanosine triphosphate (GTP) and Mg2+, respectively, specific for all PEPCKs. In the kinase-1 motifs the GK was changed to RK. The first 19 amino acids of the putative enzyme contain hydrophobic amino acids and hydroxylated residues specific to a mitochondrial type signal. The PEPCK is expressed in hepatopancreas, muscles, nervous system, heart, and gills. Hyperosmotic stress for 24 h increased the PEPCK mRNA level, gluconeogenic and PEPCK activities in muscle

Characterization and Expression of Glutamate Dehydrogenase in Response to Acute Salinity Stress in the Chinese Mitten Crab, Eriocheir sinensis

Glutamate dehydrogenase (GDH) is a key enzyme for the synthesis and catabolism of glutamic acid, proline and alanine, which are important osmolytes in aquatic animals. However, the response of GDH gene expression to salinity alterations has not yet been determined in macro-crustacean species.GDH cDNA was isolated from Eriocheir sinensis. Then, GDH gene expression was analyzed in different tissues from normal crabs and the muscle of crabs following transfer from freshwater (control) directly to water with salinities of 16‰ and 30‰, respectively. Full-length GDH cDNA is 2,349 bp, consisting of a 76 bp 5'- untranslated region, a 1,695 bp open reading frame encoding 564 amino acids and a 578 bp 3'- untranslated region. E. sinensis GDH showed 64-90% identity with protein sequences of mammalian and crustacean species. Muscle was the dominant expression source among all tissues tested. Compared with the control, GDH expression significantly increased at 6 h in crabs transferred to 16‰ and 30‰ salinity, and GDH expression peaked at 48 h and 12 h, respectively, with levels approximately 7.9 and 8.5 fold higher than the control. The free amino acid (FAA) changes in muscle, under acute salinity stress (16‰ and 30‰ salinities), correlated with GDH expression levels. Total FAA content in the muscle, which was based on specific changes in arginine, proline, glycine, alanine, taurine, serine and glutamic acid, tended to increase in crabs following transfer to salt water. Among these, arginine, proline and alanine increased significantly during salinity acclimation and accounted for the highest proportion of total FAA.E. sinensis GDH is a conserved protein that serves important functions in controlling osmoregulation. We observed that higher GDH expression after ambient salinity increase led to higher FAA metabolism, especially the synthesis of glutamic acid, which increased the synthesis of proline and alanine to meet the demand of osmoregulation at hyperosmotic conditions

Étude des voies métaboliques des sucres chez l'huître creuse Crassostrea gigas (implication dans les mortalités estivales)

L'objectif de ce travail de thèse était d'étudier les voies de synthèse et de dégradation du glycogène en relation avec la reproduction et les mortalités estivales de l'huître Crassostrea gigas. Les séquences complètes des ARNm de la glycogène phosphorylase (Cg-GPH) et de la glycogène synthase (Cg-GYS) ont été caractérisées. Les périodes de forte abondance de ces transcrits manquent chacune une phase opposée du cycle énergétique du glycogène (utilisation ou accumulation respectivement). Il n'existe cependant aucune opposition saisonnière des activités enzymatiques correspondantes. Bien que l'apport en algues induise in vivo une activation de la synthèse du glycogène, aucun effet fonctionnel du glucose et de l'insuline porcine n'est observé in vitro sur les enzymes du métabolisme du glycogène. En contribution au projet national MOREST (MORtalités ESTivales de C. Gigas), l'étude a été étendue à plusieurs marqueurs du métabolisme des glucides. Des huîtres sélectionnées pour leur résistance (R) ou leur sensibilité (S) aux mortalités auraient différentes stratégies énergétiques. L'avantage glycolytique observé pour les huîtres R leur permettrait peut-être de répondre plus favorablement à des stress environnementaux en période estivale.Glycogen, the main form of glucose reserve in bivalves, is know to play a key energetic role in the Pacific oyster (Crassostrea gigas) annual reproduction cycle. The aim of this work was to study the pathways of glycogen synthesis and utilization in order to explain the relationships between energy, reproduction and oyster summer mortality events. We first characterized full length mRNA sequences of glycogen synthase (Cg-GYS) and glycogen phosphorylase (Cg-GPH). Biochemical determination of enzymatic activities and adjustment of a RNA absolute quantification method allowed us to study several regulation levels for both markers. Quantities of Cg-GYS and Cg-GPH mRNAs showed seasonal variations, with opposite maximum periods, corresponding to glycogen accumulation or utilization. However, no difference was detected in the enzymatic activities of glycogen synthase (GS) and glycogen phosphorylase (GP), thus suggesting that several levels of regulation may exist in the control of C. gigas glycogen metabolism. Moreover, glycogen synthesis was up regulated in vivo by increasing algal diet but neither glucose nor porcine insulin had any effect in vitro on GS and GP activities. Finally, in contribution to the French project MOREST (C. gigas summer mortality), we extended this work by analyzing mRNAs quantities and enzymatic activities of several elements insolved in the glucose metabolism. Oysters genetically selected for Resistance (R) or Susceptibility (S) to summer mortality may have different strategies of glucose utilization. The potential energetic advantage of R oyster compared to S oyster is discussed.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

On two rare and poorly known species, Stylodactylus discissipes Bate, 1888, and S. serratus A. Milne-Edwards, 1881 (Crustacea, Decapoda, Stylodactylidae)

Cleva, Régis, Wormhoudt, Alain Van (2006): On two rare and poorly known species, Stylodactylus discissipes Bate, 1888, and S. serratus A. Milne-Edwards, 1881 (Crustacea, Decapoda, Stylodactylidae). Zoosystema 28 (2): 347-358, DOI: http://doi.org/10.5281/zenodo.540156

À propos de deux espèces rares et peu connues, <i>Stylodactylus discissipes</i> Bate, 1888, et <i>S. serratus</i> A. Milne-Edwards, 1881 (Crustacea, Decapoda, Stylodactylidae)

Plus d’un siècle après sa description des îles Kermadec, au nord de la Nouvelle-Zélande, Stylodactylus discissipes Bate, 1888 est retrouvé au sud de la Nouvelle-Calédonie et aux îles Australes (Polynésie française). Les analyses moléculaires permettent d’établir que les spécimens provenant de ces deux régions éloignées appartiennent bien au même taxon et semblent indiquer par ailleurs qu’il s’agit de deux populations qui commencent à s’isoler. Stylodactylus discissipes partage de nombreux de caractères avec S. serratus A. Milne-Edwards, 1881, signalé des deux côtés de l’Atlantique, à tel point que la synonymie de ces deux espèces pouvait être envisagée. Les données moléculaires viennent en appui des petites différences morphologiques observées et confirment que nous nous trouvons bien devant deux espèces distinctes.More than a century after its description from the Kermadec Islands, north of New Zealand, Stylodactylus discissipes Bate, 1888 has been rediscovered south of New Caledonia, and in the Austral Islands, French Polynesia. DNA analyses show that specimens from these two widely separated areas clearly belong to the same species, and represent two populations that appear to be in early stages of speciation through isolation. Stylodactylus discissipes shares numerous morphological characters with S. serratus A. Milne-Edwards, 1881, known from the eastern and western Atlantic, so that the synonymy of the two species could be considered. Molecular data support the small morphological differences observed, giving evidence that these two species are indeed different.</p

Caractérisation biochimique et moléculaire de différentes populations de palourdes tunisiennes (rôle de la Leucine Aminopeptidase dans l'adaptation à la salinité)

L étude de la diversité et de la structuration génétique populationnelle des organismes marins est une approche principale pour la mise en place de mesures de gestion et de conservation pour les espèces exploitées. L étude de la variabilité génétique des populations de Ruditapes decussatus, des côtes Nord et côtes Est tunisiennes situées respectivement dans les bassins Ouest et Est de la Méditerranée, est abordée par l analyse de différents types de marqueurs. L analyse du polymorphisme de neuf loci allozymiques a montré une nette structuration génétique des populations de R. decussatus de part et d autre du détroit Siculo-Tunisien. Cette structuration semble être le reflet de processus historique et contemporain : une intergradation, probablement secondaire, est confirmée par une variation clinale observée pour 60% des loci polymorphes avec un point de rupture qui coïncide avec le détroit S-T, zone d hybridation entre les deux bassins. L analyse du polymorphisme du fragment du gène de la COI et de la région ITS1 a confirmé la présence d une variation clinale au niveau d un haplotype majoritaire de COI et au niveau de trois parmi les cinq haplotypes majoritaires de ITS1. L absence de différenciation entre populations sur la base des données des deux marqueurs COI et ITS1 peut être expliquée, du moins en partie, par les fortes fréquences des haplotypes rares qui pourraient traduire les effets d une expansion démographique récente qui masqueraient une réelle structuration génétique ancienne. La capacité adaptative des palourdes face au facteur salinité a été évaluée par l étude d un marqueur enzymatique (Lap-1). Les expérimentations de survie menées en milieux hypo et hyper osmotiques ont montré que la palourde Tunisienne est bien adaptée aux variations de salinité entre 10ppm et 50ppm. Cette capacité adaptative n est pas liée à la Lap-1 qui s est révélée hétéromorphe chez la palourde Tunisienne par comparaison à la palourde de Bretagne.Knowledge about population diversity and structure is among the most important questions to investigate, especially concerning exploited species. Genetic variability of R. decussatus populations collected from localities in the eastern and western Mediterranean coasts of Tunisia was examined using different markers. Genetic polymorphism of nine allozyme loci showed a significant clustering of all samples in two main divergent groups on either sides of the Siculo-Tunisian strait. This pattern seems to be the result of historical and contemporary process: a plausible model of secondary intergradation is supported by the observation of coincident clines at nearly 60% of the polymorphic loci that were centered at the Siculo-Tunisian strait region (area of transition from the western Mediterranean basin to the eastern one). Analysis of partial sequence of mitochondrial COI gene and of the internal transcribed spacer region (ITS-1) revealed significant clinal changes in haplotypes frequencies between eastern and western samples at the focal COI haplotype and at three out of five focal ITS1 haplotypes. In the present study, no significant difference was found among groups. However, high frequencies of rare and unique haplotypes could reflect the effects of a recent demographic expansion which would mask a real ancient and significant genetic differentiation displayed by the two basins. Adaptive response to salinity stress in R. decussatus was evaluated by the study of an enzymatic marker (Lap -1). Experiments carried out in hypo osmotic and hyper osmotic stress showed that the Tunisian clam is well adapted to salinity variations between 10ppm and 50ppm. The Adaptive capacity to different salinities seems to be not related to Lap-1 which was polymorphic in the Tunisian clam, on the contrary to R. decussatus from Brittany.PARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Adaptation of digestive enzymes to dietary protein, carbohydrate and fibre levels and influence of protein and carbohydrate quality in

Activity of digestive enzymes (trypsin, chymotrypsin and amylase) was studied in relation with food in Penaeus vannamei larvae first stages. Microparticles containing casein involved the decrease of soluble protein content and enzyme activities. Specific trypsin activity but not chymotrypsin was correlated (p < 1%) to casein level between 10 and 60% in microparticles. Cellulose fibres in food seemed to have little effect on digestive enzymes. Starch, between 1 and 20% in microparticles, had no influence on specific amylase activity. The effect of different feeding conditions were also tested on growth. No clear relationship between growth and enzyme is established since only trypsin is concerned in the case of a casein dose effect in the food. The protein source (casein, gelatin, squid meal or fish protein soluble concentrate) as well as the carbohydrate quality (soluble starch, standard corn starch, amylopectin corn starch or pregelatinized corn starch) were tested. Squid meal stimulated significantly chymotrypsin activity (p < 2%) while trypsin activity decreased with fish protein soluble concentrate p < 5%). Source of carbohydrate seemed very important, amylase activity increased significantly ( p < 2%) with corn starch. These adaptations are not correlated to growth performances since squid meal or fish protein soluble concentrate improved larval development until zoe 3 substage. These results suggest a specific induction of digestive enzymes to the food quality in larvae independent of growth performances