Effect of probiotic Pediococcus acidilactici on antioxidant defences and oxidative stress of Litopenaeus stylirostris under Vibrio nigripulchritudo challenge Auteur(s) : Castex, Mathieu Lemaire, Pierrette Wabete, Nelly Chim, Liet Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd Résumé : Antioxidant defences and induced oxidative stress tissue damage of the blue shrimp Litopenaeus stylirostris, under challenge with Vibrio nigriputchritudo, were investigated for a 72-h period. For this purpose, L stylirostris were first infected by immersion with pathogenic V. nigripulchritudo strain SFn1 and then antioxidant defences: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (Gpx), Total antioxidant status (TAS), glutathiones and induced tissue damage (MDA and carbonyl proteins) were determined in the digestive gland at 0, 12, 24, 48 and 72 h post-infection (h.p.i.). In the meantime, TAS was also measured in the blood. Infection level of the shrimps during the challenge was followed by determining V. nigripulchritudo prevalence and load in the haemolymph of the shrimps. Changes in all these parameters during the 72-h.p.i. period were recorded for control shrimps and shrimps previously fed for one month with probiotic Pediococcus aciditactici MA18/5M at 10(7) CFU g(-1) of feed. Our results showed that immersion with V nigripulchritudo led to maximal infection level in the haemolymph at 24 h.p.i. preceding the mortality peak recorded at 48 h.p.i. Significant decreases in the antioxidant defences were detected from 24 h.p.i. and beyond that time infection leaded to increases in oxidative stress level and tissue damage.. Compared to control group, shrimps fed the probiotic diet showed lower infection (20% instead of 45% at 24 h.p.i. in the control group) and mortality (25% instead of 41.7% in the control group) levels. Moreover, infected shrimp fed the probiotic compared to uninfected control shrimps exhibited very similar antioxidant status and oxidative stress level. Compared to the infected control group, shrimps fed the probiotic sustained higher antioxidant defences and lower oxidative stress level. This study shows that bacterial infection leads to oxidative stress in L. stylirostris and highlighted a beneficial effect of P. acidilactici, suggesting both a competitive exclusion effect leading to a reduction of the infection level and/or an enhancement of the antioxidant status of the shrimps. (C) 2010 Elsevier Ltd. All rights reserved. Fish & Shellfish Immunology (1050-4648) (Academic Press Ltd- Elsevier Science Ltd), 2010-04 , Vol. 28 , N. 4 , P. 622-631 Droits : 2010 Elsevier Ltd All rights reserved. http://archimer.ifremer.fr/doc/00003/11419/7984.pdf DOI:10.1016/j.fsi.2009.12.024 http://archimer.ifremer.fr/doc/00003/11419/ | Partager Voir aussi Probiotic Pediococcus acidilactici Shrimp Oxidative stress Antioxidant status Vibrio Immersion challenge Télécharger |
Does coastal lagoon habitat quality affect fish growth rate and their recruitment? Insights from fishing and acoustic surveys Auteur(s) : Brehmer, Patrice Laugier, Thierry Kantoussan, J. Galgani, Francois Mouillot, D. Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd Résumé : Ensuring the sustainability of fish resources necessitates understanding their interaction with coastal habitats, which is becoming ever more challenging in the context of ever increasing anthropogenic pressures. The ability of coastal lagoons, exposed to major sources of disturbance, to provide resources and suitable habitats for growth and survival of juvenile fish is especially important. We analysed three lagoons with different ecological statuses and habitat quality on the basis of their eutrophication and ecotoxicity (Trix test) levels. Fish abundances were sampled using fishing and horizontal beaming acoustic surveys with the same protocols in the same year. The relative abundance of Anguilla anguilla, Dicentrarchus labrax or the Mugilidae group was not an indicator of habitat quality, whereas Atherina boyeri and Sparus aurata appeared to be more sensitive to habitat quality. Fish abundance was higher in the two lagoons with high eutrophication and ecotoxicity levels than in the less impacted lagoon, while fish sizes were significantly higher in the two most severely impacted lagoons. This leads us to suggest low habitat quality may increase fish growth rate (by the mean of a cascading effect), but may reduce lagoon juvenile abundance by increasing larval mortality. Such a hypothesis needs to be further validated using greater investigations which take into account more influences on fish growth and recruitment in such variable environments under complex multi-stressor conditions. Estuarine Coastal And Shelf Science (0272-7714) (Academic Press Ltd- Elsevier Science Ltd), 2013-07 , Vol. 126 , P. 1-6 Droits : 2013 Elsevier Ltd. All rights reserved http://archimer.ifremer.fr/doc/00148/25963/24083.pdf DOI:10.1016/j.ecss.2013.03.011 http://archimer.ifremer.fr/doc/00148/25963/ | Partager |
Insights into the antiviral functions of the RNAi machinery in penaeid shrimp Auteur(s) : Labreuche, Yannick Warr, Gregory W. Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd Résumé : Over the last decade, RNA interference pathways have emerged in eukaryotes as critical regulators of many diverse biological functions including, among others, transcriptional gene regulation, post-transcriptional gene silencing, heterochromatin remodelling, suppression of transposon activity, and antiviral defences. Although this gene silencing process has been reported to be relatively well conserved in species of different phyla, there are important discrepancies between plants, invertebrates and mammals. In penaeid shrimp, the existence of an intact and functional RNAi machinery is supported by a rapidly growing body of evidence. However, the extent to which this process participates to the host immune responses remains poorly defined in this non-model organism. This review summarizes our current knowledge of RNAi mechanisms in shrimp and focuses on their implication in antiviral activities and shrimp immune defences. Fish & Shellfish Immunology (1050-4648) (Academic Press Ltd- Elsevier Science Ltd), 2013-04 , Vol. 34 , N. 4 , P. 1002-1010 Droits : 2012 Elsevier Ltd. Published by Elsevier Ltd http://archimer.ifremer.fr/doc/00119/23063/20899.pdf DOI:10.1016/j.fsi.2012.06.008 http://archimer.ifremer.fr/doc/00119/23063/ | Partager |
New insights in flat oyster Ostrea edulis resistance against the parasite Bonamia ostreae Auteur(s) : Morga, Benjamin Renault, Tristan Faury, Nicole Arzul, Isabelle Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd Résumé : Bonamiosis due to the parasite Bonamia ostreae has been associated with massive mortality in flat oyster stocks in Europe. Control of the disease currently relies on disease management practices and transfer restriction. Previously, massal selections based on survival to challenge to infection with B. ostreae have been applied to produce flat oyster families with resistant progeny. In an attempt to understand the molecular mechanisms involved in disease resistance, differentially expressed sequence tags between resistant and wild Ostrea edulis haemocytes, both infected with the parasite, were identified using suppression subtractive hybridisation. Expression of seven ESTs has been studied using quantitative reverse-transcriptase PCR. The base-line expression of an extracellular superoxide dismutase, inhibitor of apoptosis (OeIAP), Fas ligand (OeFas-ligand) and Cathepsin B was significantly increased, whilst cyclophilin B appeared significantly decreased in resistant oysters. Considering their great interest for further studies, the open reading frames of the OeFas-ligand and OeIAP were completely sequenced. Highlights ► Bonamia ostreae is an intra-haemocytes parasite. ► Flat oyster Ostrea edulis, is the natural host of B. ostreae. ► In this study we have studied genes expressed in response to the parasite. ► Extracellular superoxide dismutase (OeEcSOD) is up regulated in resistant haemocyte. ► Genes involved in apoptosis is up regulated in resistant haemocytes from flat oyster. Fish & Shellfish Immunology (1050-4648) (Academic Press Ltd- Elsevier Science Ltd), 2012-06 , Vol. 32 , N. 6 , P. 958-968 Droits : 2012 Elsevier Ltd. All rights reserved. http://archimer.ifremer.fr/doc/00071/18218/15790.pdf DOI:10.1016/j.fsi.2012.01.026 http://archimer.ifremer.fr/doc/00071/18218/ | Partager |
A systematic review of socio-economic assessments in support of coastal zone management (1992-2011) Auteur(s) : Le Gentil, Eric Mongruel, Remi Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd Résumé : Cooperation between the social and natural sciences has become essential in order to encompass all the dimensions of coastal zone management. Socio-economic approaches are increasingly recommended to complement integrated assessment in support of these initiatives. A systematic review of the academic literature was carried out in order to analyze the main types of socio-economic assessments used to inform the coastal zone management process as well as their effectiveness. A corpus of 1682 articles published between 1992 and 2011 was identified by means of the representative coverage approach, from which 170 were selected by applying inclusion/exclusion criteria and then classified using a content analysis methodology. The percentage of articles that mention the use of socio-economic assessment in support of coastal zone management initiatives is increasing but remains relatively low. The review examines the links between the issues addressed by integrated assessments and the chosen analytical frameworks as well as the various economic assessment methods which are used in the successive steps of the coastal zone management process. The results show that i) analytical frameworks such as 'risk and vulnerability', 'DPSIR', 'valuation', 'ecosystem services' and 'preferences' are likely to lead to effective integration of social sciences in coastal zone management research while 'integration', 'sustainability' and 'participation' remain difficult to operationalize, ii) risk assessments are insufficiently implemented in developing countries, and iii) indicator systems in support of multi-criteria analyses could be used during more stages of the coastal zone management process. Finally, it is suggested that improved collaboration between science and management would require that scientists currently involved in coastal zone management processes further educate themselves in integrated assessment approaches and participatory methodologies. Journal Of Environmental Management (0301-4797) (Academic Press Ltd- Elsevier Science Ltd), 2015-02-01 , Vol. 149 , P. 85-96 Droits : 2014 Elsevier Ltd. All rights reserved. http://archimer.ifremer.fr/doc/00255/36598/35167.pdf DOI:10.1016/j.jenvman.2014.10.018 http://archimer.ifremer.fr/doc/00255/36598/ | Partager Voir aussi Integrated coastal zone management Integrated assessment Socio-economic assessment Systematic review Télécharger |
Vibriosis induced by experimental cohabitation in Crassostrea gigas: Evidence of early infection and down-expression of immune-related genes Auteur(s) : De Decker, Sophie Saulnier, Denis Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd Résumé : The understanding of reciprocal interactions between Crassostrea gigas and Vibrio sp., whether these be virulent or avirulent, is vital for the development of methods to improve the health status of cultured oysters. We describe an original non-invasive experimental infection technique using cohabitation, designed to explore these interactions. Using real-time PCR techniques we examined the dynamics of virulent and avirulent Vibrio sp. in oyster hemolymph and tank seawater, and made a parallel study of the expression of four genes involved in oyster immune defense: Cg-BPI, Cg-EcSOD, Cg-IκB, Cg-TIMP. No mortality occurred in control animals, but oysters put in cohabitation for 2–48 h with animals previously infected by two Vibrio pathogens suffered mortalities from 2 to 16 days post-cohabitation. Our results show that virulent Vibrio infect healthy individuals after only 2 h of cohabitation, with values ranging from 4.5×102 to 2×104 cells ml−1 hemolymph. Simultaneously, an approximate ten-fold increase of the total Vibrio population was observed in control animals, with a 6.6–78.5-fold up-expression of targeted genes. In contrast, oysters exposed to harmful bacteria had mean expression levels strongly down-regulated by a factor of 9.2–29 (depending on the gene) compared with control animals. Although oysters were still found to be infected by virulent Vibrio after 6–48 h of cohabitation, no significant differences were noted when comparing levels of each transcript in control and infected oysters at the same sampling times during this period: the important differences were noted before 6 h cohabitation. Taken together, our data support (1) the hypothesis that virulent Vibrio disturbs the immune response of this invertebrate host both rapidly and significantly, although this occurs specifically during an early and transient period during the first 6 h of cohabitation challenge, and that (2) expression of targeted genes is not correlated with vibriosis resistance. Fish & Shellfish Immunology (1050-4648) (Academic Press Ltd- Elsevier Science Ltd), 2011-02 , Vol. 30 , N. 2 , P. 691-699 Droits : 2011 Elsevier Ltd All rights reserved. http://archimer.ifremer.fr/doc/00025/13604/10681.pdf DOI:10.1016/j.fsi.2010.12.017 http://archimer.ifremer.fr/doc/00025/13604/ | Partager Voir aussi Oyster-Vibrio interactions Pathogenesis Immune response Non-invasive experimental challenge Real-time PCR Télécharger |
Vibrio aestuarianus zinc metalloprotease causes lethality in the Pacific oyster Crassostrea gigas and impairs the host cellular immune defenses Auteur(s) : Labreuche, Yannick Le Roux, Frederique Henry, Joel Zatylny, Celine Huvet, Arnaud Lambert, Christophe Soudant, Philippe Mazel, Didier Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd Résumé : Extracellular products (ECPs) of the pathogenic Vibrio aestuarianus 01/32 were previously reported to display lethality in Crassostrea gigas oysters and to cause morphological changes and immunosuppression in oyster hemocytes. To identify the source of this toxicity, biochemical and genetic approaches were developed. ECP protease activity and lethality were shown to be significantly reduced following incubation with metal chelators, suggesting the involvement of a zinc metalloprotease. An open reading frame of 1836 bp encoding a 611-aa metalloprotease (designated yam) was identified. The deduced protein sequence showed high homology to other Vibrio metalloproteases reported to be involved in pathogenicity. To further confirm the role of this enzyme in ECP toxicity, a plasmid carrying the yarn gene under the control of an araC-P-BAD expression cassette was transferred to a Vibrio splendidus related strain, LMC20012(T), previously characterized as non-pathogenic to oysters. Expression of Vam conferred a toxic phenotype to LMG20012(T) ECPs in vivo and cytotoxicity to oyster hemocytes in vitro. Collectively, these data suggest that the Vam metalloprotease is a major contributor to the toxicity induced by V aestuarianus ECPs and is involved in the impairment of oyster hemocyte functions. (C) 2010 Elsevier Ltd. All rights reserved. Fish & Shellfish Immunology (1050-4648) (Academic Press Ltd- Elsevier Science Ltd), 2010-11 , Vol. 29 , N. 5 , P. 753-758 Droits : 2010 Elsevier Ltd All rights reserved. http://archimer.ifremer.fr/doc/00015/12649/9588.pdf DOI:10.1016/j.fsi.2010.07.007 http://archimer.ifremer.fr/doc/00015/12649/ | Partager Voir aussi Vibrio aestuarianus Metalloprotease Crassostrea gigas Oyster Hemocytes Extracellular products Télécharger |
The aggregation of tuna around floating objects: What could be the underlying social mechanisms? Auteur(s) : Robert, Marianne Dagorn, Laurent Deneubourg, Jean Louis Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd Résumé : Several empirical and theoretical studies have shown how the exploitation of food sources, the choice of resting sites or other types of collective decision-making in heterogeneous environments are facilitated and modulated by social interactions between conspecifics. It is well known that many pelagic fishes live in schools and that this form of gregarious behavior provides advantages in terms of food intake and predator avoidance efficiency. However, the influence of social behavior in the formation of aggregations by tuna under floating objects (FOBs) is poorly understood. In this work, we investigated the collective patterns generated by different theoretical models, which either include or exclude social interactions between conspecifics, in the presence of two aggregation sites. The resulting temporal dynamics and distributions of populations were compared to in situ observations of tuna behavior. Our work suggests that social interactions should be incorporated in aggregative behavior to reproduce the temporal patterns observed in the field at both the individual and the group level, challenging the common vision of tuna aggregations around FOBs. Our study argues for additional data to further demonstrate the role of social behavior in the dynamics of these fish aggregations. Understanding the interplay between environmental and social factors in the associative behavior of fish with FOBs is necessary to assess the consequences of the widespread deployment of artificial FOBs by fishermen. Journal Of Theoretical Biology (0022-5193) (Academic Press Ltd- Elsevier Science Ltd), 2014-10 , Vol. 359 , P. 161-170 Droits : 2014 Elsevier Ltd. All rights reserved. http://archimer.ifremer.fr/doc/00195/30638/29091.pdf DOI:10.1016/j.jtbi.2014.06.010 http://archimer.ifremer.fr/doc/00195/30638/ | Partager Voir aussi Models of aggregation Monte Carlo multi-agents simulations Fish aggregating devices Social behavior Télécharger |
Spatio-temporal variability in benthic silica cycling in two macrotidal estuaries: Causes and consequences for local to global studies Auteur(s) : Raimonet, Melanie Ragueneau, Olivier Andrieux Loyer, Francoise Philippon, Xavier Kerouel, Roger Le Goff, Manon Memery, Laurent Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd Résumé : The high heterogeneity of silica cycling in coastal margins and the lack of silica data (compared to nitrogen and phosphorus) prevent the estimation of global silica retention in estuaries. In this study, the spatial and temporal variability of porewater silicic acid (Si(OH)4) profiles e that integrate benthic transport and reaction processes e was investigated at different spatial (metre, longitudinal and crosssection, intra-estuary) and temporal (tidal, seasonal) scales in two macrotidal estuaries, very close geographically but essentially differing in their shape. Studying the spatial and temporal variability of Si(OH)4 concentrations in porewaters provided evidence for the importance of transport processes, e.g. bio-irrigation, tidal pumping, resuspension and any combination of these processes, in affecting Si(OH)4 concentrations and fluxes and therefore temporary or permanent retention along the landeocean continuum. We confirm that aSiO2 (amorphous silicate) transported by rivers and estuaries clearly needs to be better characterized as it provides an important source of reactive aSiO2 to sediments. This study allows us to: (1) interrogate spatial and temporal scales, although both are most often in complete interaction; (2) design the most appropriate sampling schemes to be representative of any given system and to extrapolate at the scale of the whole estuary; (3) quantify uncertainty associated to the estimations of Si(OH)4 stocks and fluxes in this type of ecosystem, essential for budget calculations. We showed that two adjacent small macrotidal estuaries, may exhibit different behaviours regarding Si retention. Temporary retention has been observed in the meanders of the Aulne Estuary and not along the more linear Elorn Estuary, demonstrating the importance of the morphology and hydrodynamic components of the estuarine filter. Research is needed in other systems and climatic zones, but our study suggests that the typology should not only account for the different types of landeocean continuum (fjord, delta, mangrove.), but also incorporate the physical or biological attributes of the estuarine filter. Estuarine Coastal And Shelf Science (0272-7714) (Academic Press Ltd- Elsevier Science Ltd), 2013-03 , Vol. 119 , P. 31-43 Droits : 2013 Elsevier Ltd. All rights reserved. http://archimer.ifremer.fr/doc/00124/23529/22370.pdf DOI:10.1016/j.ecss.2012.12.008 http://archimer.ifremer.fr/doc/00124/23529/ | Partager |