Éditeur(s) : Elsevier Science Inc
Résumé : Based on multi-sensor optical remote sensing techniques, more than 80 medium and high spatial resolution satellite images were used for studying the turbidity patterns of Danube Delta waters. During a selected 4-year temporal coverage (2006 to 2009), the turbidity gradients were simultaneously analyzed in the delta plain lakes and in the Black Sea western-northwestern coastal zone. Two distinct, but complementary, methodologies for retrieving turbidity were employed, one for the lakes and the other for the coastal zone. After comparing the turbidity satellite-derived turbidity products with in-situ measurements, the inter-comparability of the products was independently verified. Then, through an integrative analysis, the initial hypothesis of turbidity control by the Danube River inputs was tested in both areas (Delta plain and coastal zone). Seasonal turbidity patterns were identified together with the mechanisms responsible for its important temporal and spatial variability. Reciprocal contributions derived from the association of multi-scale satellite products were highlighted. (C) 2013 Elsevier Inc. All rights reserved.
Remote Sensing Of Environment (0034-4257) (Elsevier Science Inc), 2013-05 , Vol. 132 , P. 86-101

Droits : 2013 Elsevier Inc. All rights reserved.
http://archimer.ifremer.fr/doc/00135/24622/23607.pdf
DOI:10.1016/j.rse.2013.01.009
http://archimer.ifremer.fr/doc/00135/24622/

Éditeur(s) : Elsevier Science Inc
Résumé : The sex-determining system of Crassostrea gigas is still poorly known, especially regarding the potential influence of temperature. In order to address this question, mRNA expressions of actors of the molecular cascade (Cg-DMI, Cg-SoxE, Cg-beta-catenin, Cg-Foxl2/Cg-FoxI2os) and of Oyvlg, a germ cell marker, were investigated by real-time PCR in spat grown at different temperatures (18, 22, 25 and 28 degrees C). In parallel, gonadic differentiation, gametogenesis and sex ratios were assessed by histology at each of these temperatures. Whatever the temperature, Cg-DMI, Cg-SoxE, Cg-beta-catenin and Oyvlg expressions peaked at the same developmental stage, always after Cg-Foxl2/Cg-Foxl2os (around 40-44 dpf for spat grown at 18 degrees C). Temperatures increased the kinetics of first gonadic differentiation and gametogenesis. At 25 degrees C a significant switch occurred in sex ratio towards males and in the balance of expression between male and female genes, in favor of males. A slight gametogenesis disturbance was also observed. These results strengthen the hypotheses about the sex-determining time window and molecular cascade governing the development of C gigas, with notably the involvement of Cg-Foxl2/Cg-Foxl2os in the very early steps. They also suggest an influence of temperature on the oyster's sex determination which, associated to genetic control, would induce a mixed sex determination system (GSD +TSD). (C) 2013 Elsevier Inc. All rights reserved.
Comparative Biochemistry And Physiology A-molecular & Integrative Physiology (1095-6433) (Elsevier Science Inc), 2013-05 , Vol. 165 , N. 1 , P. 61-69

Droits : 2013 Elsevier Inc. All rights reserved
http://archimer.ifremer.fr/doc/00136/24767/22874.pdf
DOI:10.1016/j.cbpa.2013.02.007
http://archimer.ifremer.fr/doc/00136/24767/

Éditeur(s) : Academic Press Inc Elsevier Science
Résumé : Several Vibrio species are known to be pathogenic to the Pacific oyster Crassostrea gigas. Survival varies according to pathogen exposure and high mortality events usually occur in summer during gametogenesis. In order to study the effects of gametogenetic status and ploidy (a factor known to affect reproduction allocation in oysters) on vibriosis survival, we conducted two successive experiments. Our results demonstrate that a common bath challenge with pathogenic Vibrio splendidus and Vibrio aestuarianus on a mixture of mature, spawning and non-mature oysters can lead to significant mortality. Previous bath challenges, which were done using only non-mature oysters, had not produced mortality. Immunohisto-chemical analyses showed the affinity of Vibrio for gonadic tissues, highlighting the importance of sexual maturity for vibriosis infection processes in oysters. Mortality rate results showed poor repeatability between tanks, however, in this bath challenge. We then tested a standardized and repeatable injection protocol using two different doses of the same combination of two Vibrio species on related diploid and triploid oysters at four different times over a year. Statistical analyses of mortality kinetics over a 6-day period after injection revealed that active gametogenesis periods correspond to higher susceptibility to vibriosis and that there is a significant interaction of this seasonal effect with ploidy. However, no significant advantage of triploidy was observed. Triploid oysters even showed lower survival than diploid counterparts in winter. Results are discussed in relation to differing energy allocation patterns between diploid and triploid Pacific oysters. (C) 2010 Elsevier Inc. All rights reserved.
Journal Of Invertebrate Pathology (0022-2011) (Academic Press Inc Elsevier Science), 2011-02 , Vol. 106 , N. 2 , P. 179-191

Droits : 2010 Elsevier Inc. All rights reserved.
http://archimer.ifremer.fr/doc/00030/14108/11368.pdf
DOI:10.1016/j.jip.2010.09.003
http://archimer.ifremer.fr/doc/00030/14108/

Éditeur(s) : Academic Press Inc Elsevier Science
Molecular Phylogenetics And Evolution (1055-7903) (Academic Press Inc Elsevier Science), 2008-01 , Vol. 46 , N. 1 , P. 375-381

Droits : 2008 Elsevier Inc. All rights reserved
http://archimer.ifremer.fr/doc/2008/publication-3736.pdf
DOI:10.1016/j.ympev.2007.04.002
http://archimer.ifremer.fr/doc/00000/3736/