Recirculation aquaculture system (RAS) is the type of land-based aquaculture productionthat interferes the least with the environment, particularly due to low effluent volumeand overall water requirement. Water reuse, sometimes limited by the accumulation of wasteproducts excreted by fish, can be improved by incorporating another biotechnical componentin the form of high rate algal pond (RAS+HRAP), thus adding to the economy and selfsustainability of the system. Our goal was to evaluate whether rearing fish for 1 year ina RAS or RAS+HRAP led to differences in fish production and health, by assessing: (1) fishgrowth; (2) impact on the morphological structure of sea bass target tissues (liver,kidney, and spleen); (3) susceptibility to monogenean parasites; (4) resistance topathogen challenge with Listonella anguillarum; and (5) total bloodprotein. Over the one-year experimental period, sea bass showed no statistical differencesin any parameter evaluated, suggesting that there was a satisfactory purification rate inthe RAS+HRAP system.

The immune system maintains appropriate cell numbers through regulation of cell proliferation and death. Normal tissue distribution of lymphocytes is maintained through expression of specific adhesion molecules and chemokine receptors such as L-selectin and CCR7, respectively. Lymphocyte insufficiency or lymphopenia induces homeostatic proliferation of existing lymphocytes to increase cell numbers. Interestingly, homeostatic proliferation of T lymphocytes induces a phenotypic change from naïve- to memory-type cell. Naïve T cells recirculate between blood and lymphoid tissues whereas memory T cells migrate to nonlymphoid sites such as skin and gut. To assess effects of homeostatic proliferation on migratory ability of T cells, a murine model of lymphopenia-induced homeostatic proliferation was used. Carboxyfluorescein diacetate, succinimidyl ester-labeled wild-type splenocytes were adoptively transferred into recombination activation gene-1-deficient mice and analyzed by flow cytometry, in vitro chemotactic and in vivo migration assays, and immunofluorescence microscopy. Homeostatically proliferated T cells acquired a mixed memory-type CD44high L-selectinhigh CCR7low phenotype. Consistent with this, chemotaxis to secondary lymphoid tissue chemokine in vitro was reduced by 22%–34%. By contrast, no differences were found for migration or entry into lymph nodes during in vivo migration assays. Therefore, T lymphocytes that have undergone homeostatic proliferation recirculate using mechanisms similar to naïve T cells.

Nous étudions l'écoulement dans le plan de sortie d'un jet tournant à grand nombre deReynolds généré à l'aide d'un nid d'abeilles tournantsuivi d'une tuyère convergente. Des mesures fil chaud réalisées en sortie de deux tuyères de taux de contraction différents montrent l'apparition progressive de turbulencepour des valeurs identiques du taux de rotation de l'écoulementen amont des tuyères. Afin d'expliquer ce phénomène, nous étudions donc la dynamique de l'écoulement de conduite compris entre le nid d'abeilles et le plan de sortie des convergents. Un modèle stationnaire simple d'écoulement est d'abord introduit. Il montre la possibilité d'unerecirculation à la paroi de la tuyère lorsque les conditions amont sont proches de la criticité,définie au sens des ondes inertielles pouvant se propager dans l'écoulement. Nous trouvons ensuiteque cessolutions sont globalement stables à des perturbations axisymétriques, mais sontsusceptibles d'amplifier fortement des perturbations de petite échelle initiées à l'amontde l'écoulement et suivies le long de leur trajectoire jusqu'en sortie.