Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The emerging orbicular batfish (Platax orbicularis) aquaculture is the most important fish aquacultureindustry in French Polynesia. However, bacterial infections are causing severe mortality episodes.Therefore, there is an urgent need to find an effective management solution. Besides the supplyingdifficulty and high costs of veterinary drugs in French Polynesia, batfish aquaculture takes place close tothe coral reef, where use of synthetic persistent drugs should be restricted. Medicinal plants andbioactive algae are emerging as a cheaper and more sustainable alternative to chemical drugs. We havestudied the effect of local Polynesian plants and the local opportunistic algae Asparagopsis taxiformis onbatfish when orally administered. Weight gain and expression of two immune-related genes (lysozyme ge Lys G and transforming growth factor beta - TGF-b1) were studied to analyze immunostimulant activityof plants on P. orbicularis. Results showed that several plants increased Lys G and TGF-b1 expressionon orbicular batfish after 2 and 3 weeks of oral administration. A. taxiformis was the plant displaying themost promising results, promoting a weight gain of 24% after 3 weeks of oral administration andsignificantly increasing the relative amount of both Lys G and TGF-b1 transcripts in kidney and spleen ofP. orbicularis.
ISSN: 1050-4648

hal-01381334
https://hal-univ-perp.archives-ouvertes.fr/hal-01381334
DOI : 10.1016/j.fsi.2016.09.011

Résumé : The New-Caledonian shrimp industry is based on the controlled reproduction of the shrimp Litopenaeus stylirostris, a species which was introduced in the 80s. The major difficulty to which the industry has been faced for 10 years is the occurrence of the "syndrome 93", which corresponds to mortality phases when the temperature falls down in April-May-June. This mortality is associated to the pathogenic bacteria Vibrio penaecida and is expressed at different levels which are variable from year ta year and from pond to pond. No resistance to this pathology has been developed spontaneously. This is likely due to the protocole used to rear spawners, which does not allow to implement an efficient selective pressure at each generation An experimental selection on the criteria of survival after picks of syndrome 93 has been conducted at the Laboratoire Aquacole de Calédonie. The 3rd selected generation demonstrates survival rates improved by 20% during experimental infections with V. penaeicida in comparison with a non selected control population of same genetic origin. The comparison of the correlated responses on the level of expression of 5 genes which are potentially implicated in immunity phenomena (Peneidins, lysozyme, transglutaminase. profiline, annexine) shows that the selected population has a level of expression in lyzozyme twice higher than the control population. This result suggests that the lysozyme could be a genetic marker which could be used in a selective breeding program to he developed in relation with the private hatcheries.
La filière crevette de Nouvelle-Calédonie repose sur la maîtrise de la reproduction contrôlée de la crevette Litopenaeus stylirostris, espèce introduite dans les années 80. La difficulté majeure que rencontre la filière depuis une dizaine d'années est la récurrence du « syndrome 93 », qui correspond à des épisodes de mortalités lors des baisses de température en avril-mai-juin. Ces mortalités sont associées à la bactérie pathogène Vibrio penaeicida et s'expriment à des niveaux d'intensité variable d'une année à l'autre et d'un bassin à l'autre. Aucune résistance vis-à-vis de cette pathologie ne s'est développée spontanément. Ceci est vraisemblablement lié au protocole employé pour l'élevage des géniteurs qui ne permet pas d'exercer une pression de sélection efficace à chaque génération. Une expérience de sélection sur un critère de survie à des épisodes de syndrome 93 a été menée au Laboratoire Aquacole de Calédonie. La 3ème génération sélectionnée montre des survies améliorées de l'ordre de 20% lors d'infections expérimentales à V. penaeicida par rapport à une population témoin non sélectionnée de même origine génétique. La comparaison des réponses corrélées sur le niveau d'expression de 5 gènes potentiellement impliqués dans les phénomènes de défense immunitaire (penaeidine, lysozyme, transglutaminase, profiline, annexine) montre que la population sélectionnée a un niveau d'expression en lysozyme deux fois plus élevé que la population témoin. Ce résultat suggère que le lysozyme pourrait être un marqueur génétique utilisable dans un programme de sélection à développer en relation avec les écloseries de production.

Droits : 2003 Ifremer
http://archimer.ifremer.fr/doc/00109/22020/19643.pdf
http://archimer.ifremer.fr/doc/00109/22020/

Éditeur(s) : Elsevier
Résumé : Understanding of antimicrobial defence mechanisms of penaeid shrimp should help in the design of efficient strategies for the management and disease control in aquaculture. In this study, we have specifically analysed the expression in circulating hemocytes of antimicrobial peptides (AMPs) encoding genes, such as PEN2 and PEN3, ALF, crustin, lysozyme and a putative cysteine-rich peptide. We evidenced a relationship between the level of expression of some AMPs and the successful response of the shrimp, Litopenaeus stylirostris, to circumvent a pathogenic Vibrio penaeicida infection. Additionally, significant differences in some AMP transcript amounts are evidenced between control, non-selected shrimp line and the third generation breeding of shrimp selected for their survival to natural V. penaeicida infections. On the basis of these results, it will now be of great interest to determine if these AMPs are directly involved in the resistance of shrimp to infection or if they only reflect other acquired defence mechanisms which can confer a resistance. (C) 2008 Elsevier Ltd. All rights reserved.
Molecular Immunology (0161-5890) (Elsevier), 2008-07 , Vol. 45 , N. 12 , P. 3438-3445

Droits : 2008 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/2008/publication-4524.pdf
DOI:10.1016/j.molimm.2008.04.002
http://archimer.ifremer.fr/doc/00000/4524/

Éditeur(s) : Elsevier Science Bv
Résumé : In New Caledonia, shrimp hatcheries are confronted with mass mortality in the larval stages, a phenomenon poorly understood as no specific causative agent has been identified. This has resulted in an excessive use of prophylactic antibiotics, although their adverse effects in aquaculture are notorious. The present work was thus aimed at selecting potential probiotic strains for penaeid hatcheries. From a pool of more than 400 marine bacterial isolates sampled from the local marine environment seven strains exhibited in vitro antagonistic activity towards Vibrio harveyi. These isolates were characterized both phenotypically and genotypically using a biochemical approach and 16S rDNA sequencing. Six out of these seven strains were found to belong to the genus Pseudoalteromonas, the last one belonging to the Vibrionaceae family and related to the Harveyi clade. Selected probiotic candidates were individually tested for antagonistic activities in vitro using a green fluorescent protein (GFP)-labelled transconjugant of V. harveyi and for inherent pathogenicity towards cultured shrimp larvae at two different developmental stages. This approach enabled rapid processing and selection of candidates to be tested in our experimental hatchery. Four different experiments were conducted to test candidate strains either alone or in combination. Repeated trials showed that postlarval survival was significantly improved by adding the strain NC201 individually to the rearing water compared to unchallenged controls. The analysis of immune-related gene expressions showed that the Litsty PEN3 transcript abundance of larvae was significantly increased after being reared in probiotic-containing water; however no significant difference in lysozyme gene expression was recorded in this study. Together, these results open new insights into the use of these strains as potential substitutes to antibiotherapy in shrimp larval rearing in New Caledonia.
Aquaculture (0044-8486) (Elsevier Science Bv), 2014-08 , Vol. 432 , P. 475-482

Droits : 2014 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00190/30129/28591.pdf
DOI:10.1016/j.aquaculture.2014.04.031
http://archimer.ifremer.fr/doc/00190/30129/