Éditeur(s) : Université Montpellier 2 - Sciences et Techniques du Languedoc
Résumé : The work reported here was motivated by the economical importance of the pacific blue shrimp Litopenaeus stylirostris farming where high mortality rates are due to bacterial and viral diseases. It consists in the characterisation of two original peptides, the first members of a new multifunctional family of peptides from peneide shrimps, the stylicines. Those two peptides, named stylicines 1 and 2, are negatively charged (pI < 6.0), and characterised by a proline-rich N-terminal region and a C-terminal region containing 13 cysteine residues. Stylicines are synthesized by heamocytes where they are stored within small cytoplasmic granules. To understand the role of these peptides in the immune response of shrimps to a vibrio infection, their recombinant forms were produced in E. coli BL21 (DE3) plysS, purified and characterised. The two rstylicines display biological anti-proliferative and blood clotting activities. Only rstylicine 1 displays antimicrobial activities: antifungal against Fusarium oxysporum (MIC<2.5μM) and bacteriostatic against Gram (−) bacteria, Vibrio sp. (MIC<80μM). Moreover this peptide displays an LPS-binding activity (dissociation constant (Kd) of 9.6×10−8 M) and agglutinate Vibrio. penaeicida "in vitro". Finally, the presence of sequences coding for modified forms of stylicine 1 in some shrimp’s genome may be in relation with their lower ability to survive infections.
Les travaux présentés dans ce mémoire ont été motivés par l’importance économique de l’élevage de la crevette bleue du pacifique Litopenaeus stylirostris dont les fortes mortalités sont principalement dues au développement de maladies bactériennes et virales. Ils ont consisté en la caractérisation des deux premiers membres d’une famille originale de peptides multifonctionnels présents chez les crevettes pénéides, les stylicines. Ces peptides, nommés stylicines 1 et 2, sont des peptides anioniques (pI < 6.0), formés d’une région amino-terminale riche en résidus de type proline et d’une région carboxyterminale riche de treize résidus cystéines. Ces molécules sont synthétisées et stockées dans de petits granules présents dans le cytoplasme des hémocytes. Pour mieux appréhender leurs rôles dans la réponse immunitaire des crevettes à une infection par des Vibrio, leurs formes recombinantes ont été produites dans E. coli BL21 (DE3) plysS, purifiées et caractérisées. Les deux rstylicines présentent des activités antiproliférative et anticoagulante. Seule la rstylicine1 présente des activités antimicrobiennes : antifongique sur Fusarium oxysporum (CMI<2.5 μM), et antibactérienne (bactériostatique) sur Vibrio sp (CMI<80 μM). Ce peptide est également capable de se lier aux LPS des bactéries à Gram (-) (Kd= 9.6x10-8 M) et d’agglutiner V. penaeicida "in vitro". Enfin, l’existence de gènes codant des formes modifiées de la stylicine1, chez certaines crevettes, pourrait être en relation avec une diminution de la résistante des individus aux infections.

Droits : 2010 The Author, Univ Montpellier 2
http://archimer.ifremer.fr/doc/00024/13558/10612.pdf
http://archimer.ifremer.fr/doc/00024/13558/

Éditeur(s) : HAL CCSD Wiley Open Access
Résumé : International audience
Coral disease outbreaks have increased over the last three decades, but their causal agents remain mostly unclear (e.g., bacteria, viruses, fungi, protists). This study details a 14-month-long survey of coral colonies in which observations of the development of disease was observed in nearly half of the sampled colonies. A bimonthly qPCR method was used to quantitatively and qualitatively evaluate Symbiodinium assemblages of tagged colonies, and to detect the presence of Vibrio spp. Firstly, our data showed that predisposition to disease development in general, and, more specifically, infection by Vibrio spp. in Acropora cytherea depended on which clades of Symbiodinium were harbored. In both cases, harboring clade D rather than A was beneficial to the coral host. Secondly, the detection of Vibrio spp. in only colonies that developed disease strongly suggests opportunistic traits of the bacteria. Finally, even if sporadic cases of switching and probably shuffling were observed, this long-term survey does not suggest specific-clade recruitment in response to stressors. Altogether, our results demonstrate that the fitness of the coral holobiont depends on its initial consortium of Symbiodinium, which is distinct among colonies, rather than a temporary adaptation achieved through acquiring different Symbiodinium clades.
ISSN: 2045-7758

hal-01346931
https://hal-uvsq.archives-ouvertes.fr/hal-01346931
https://hal-uvsq.archives-ouvertes.fr/hal-01346931/document
https://hal-uvsq.archives-ouvertes.fr/hal-01346931/file/2016%20Rouze%20EcolEvol.pdf
DOI : 10.1002/ece3.1895

Éditeur(s) : HAL CCSD Frontiers Media
Résumé : International audience
To date 142 species have been described in the Vibrionaceae family of bacteria, classified into seven genera; Aliivibrio, Echinimonas, Enterovibrio, Grimontia, Photobacterium, Salinivibrio and Vibrio. As vibrios are widespread in marine environments and show versatile metabolisms and ecologies, these bacteria are recognized as one of the most diverse and important marine heterotrophic bacterial groups for elucidating the correlation between genome evolution and ecological adaptation. However, on the basis of 16S rRNA gene phylogeny, we could not find any robust monophyletic lineages in any of the known genera. We needed further attempts to reconstruct their evolutionary history based on multilocus sequence analysis (MLSA) and/or genome wide taxonomy of all the recognized species groups. In our previous report in 2007, we conducted the first broad multilocus sequence analysis (MLSA) to infer the evolutionary history of vibrios using nine housekeeping genes (the 16S rRNA gene, gapA, gyrB, ftsZ, mreB, pyrH, recA, rpoA, and topA), and we proposed 14 distinct clades in 58 species of Vibrionaceae. Due to the difficulty of designing universal primers that can amplify the genes for MLSA in every Vibrionaceae species, some clades had yet to be defined. In this study, we present a better picture of an updated molecular phylogeny for 86 described vibrio species and 10 genome sequenced Vibrionaceae strains, using 8 housekeeping gene sequences. This new study places special emphasis on (1) eight newly identified clades (Damselae, Mediterranei, Pectenicida, Phosphoreum, Profundum, Porteresiae, Rosenbergii, and Rumoiensis); (2) clades amended since the 2007 proposal with recently described new species; (3) orphan clades of genomospecies F6 and F10; (4) phylogenetic positions defined in 3 genome-sequenced strains (N418, EX25, and EJY3); and (5) description of V. tritonius sp. nov., which is a member of the “Porteresiae” clade.
ISSN: 1664-302X

hal-01546980
http://hal.upmc.fr/hal-01546980
DOI : 10.3389/fmicb.2013.00414

Éditeur(s) : HAL CCSD Wiley Open Access
Résumé : International audience
Coral disease outbreaks have increased over the last three decades, but their causal agents remain mostly unclear (e.g., bacteria, viruses, fungi, protists). This study details a 14-month-long survey of coral colonies in which observations of the development of disease was observed in nearly half of the sampled colonies. A bimonthly qPCR method was used to quantitatively and qualitatively evaluate Symbiodinium assemblages of tagged colonies, and to detect the presence of Vibrio spp. Firstly, our data showed that predisposition to disease development in general, and, more specifically, infection by Vibrio spp. in Acropora cytherea depended on which clades of Symbiodinium were harbored. In both cases, harboring clade D rather than A was beneficial to the coral host. Secondly, the detection of Vibrio spp. in only colonies that developed disease strongly suggests opportunistic traits of the bacteria. Finally, even if sporadic cases of switching and probably shuffling were observed, this long-term survey does not suggest specific-clade recruitment in response to stressors. Altogether, our results demonstrate that the fitness of the coral holobiont depends on its initial consortium of Symbiodinium, which is distinct among colonies, rather than a temporary adaptation achieved through acquiring different Symbiodinium clades.
ISSN: 2045-7758

hal-01270779
https://hal-univ-perp.archives-ouvertes.fr/hal-01270779
https://hal-univ-perp.archives-ouvertes.fr/hal-01270779/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01270779/file/41080.pdf
DOI : 10.1002/ece3.1895

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/

Éditeur(s) : Wiley-blackwell
Résumé : Aims To describe the diversity of the culturable mesophilic and potentially pathogenic vibrios isolated at 22 and 37 degrees C on TCBS medium, in September 2009 from seawater and surface sediments. Methods and Results q-PCR assays previously selected for the identification of bacterial strains isolated at 37 degrees C were used in combination with the partial sequencing of two housekeeping genes, pyrH and toxR, to identify 315 strains isolated at 22 degrees C. The great majority of the 37 degrees C strains was identified by q-PCR assays, (five of the six species) with the predominance of Vibrio alginolyticus (85 center dot 9%) and V.harveyi (10 center dot 7%). The human pathogens V.parahaemolyticus and V.cholerae were rarely detected (two strains each). The 22 degrees C strains were successfully identified by the phylogeny analysis of pyrH and toxR genes, revealing 20 Vibrio species, with the predominance of the clam pathogen V.celticus (36 center dot 8%). The Splendidus and the Harveyi groups represented the main Vibrio group at 22 degrees C (80%) and 37 degrees C (99 center dot 5%), respectively. Conclusions The combination of q-PCR assays and the sequencing of pyrH and toxR genes highlighted two different Vibrio communities at 22 and 37 degrees C both dominated by pathogenic species for marine organisms. Significance and Impact of the Study The sequencing of the pyrH gene revealed to be a valuable tool to identify environmental Vibrio spp. strains isolated at 22 degrees C, as 92 center dot 3% of them were identified in this study.
Journal Of Applied Microbiology (1364-5072) (Wiley-blackwell), 2013-06 , Vol. 114 , N. 6 , P. 1713-1724

Droits : 2013 The Society for Applied Microbiology
http://archimer.ifremer.fr/doc/00144/25502/24832.pdf
DOI:10.1111/jam.12181
http://archimer.ifremer.fr/doc/00144/25502/

Éditeur(s) : Amer Soc Microbiology
Résumé : A molecular typing study on Vibrio strains implicated in shrimp disease outbreaks in New Caledonia and Japan was conducted by using AP-PCR (arbitrarily primed PCR). It allowed rapid identification of isolates at the genospecies level and studies of infraspecific population structures of epidemiological interest. Clusters identified within the species Vibrio penaeicida were related to their area of origin, allowing discrimination between Japanese and New Caledonian isolates, as well as between those from two different bays in New Caledonia separated by only 50 km. Other subclusters of New Caledonian V. penaeicida isolates could be identified, but it was not possible to link those differences to accurate epidemiological features. This contribution of AP-PCR to the study of vibriosis in penaeid shrimps demonstrates its high discriminating power and the relevance of the epidemiological information provided. This approach would contribute to better knowledge of the ecology of Vibrio spp. and their implication in shrimp disease in aquaculture.
Applied And Environmental Microbiology (0099-2240) (Amer Soc Microbiology), 1999-03 , Vol. 65 , N. 3 , P. 1145-1151

Droits : American society for microbiology
http://archimer.ifremer.fr/doc/1999/publication-2734.pdf
http://archimer.ifremer.fr/doc/00000/2734/

Éditeur(s) : Elsevier Science Bv
Résumé : In tropical shrimp ponds, the increasing of feed input, concomitantly with the stocking shrimp biomass, induces an eutrophication of the ecosystem. Although difficult to maintain, its stability is required to guarantee the success of the culture. A 110-day period of phytoplankton and bacterioplankton stock and dynamics in an earthen pond (1.2 ha area, 1 m depth) was monitored using flow cytometry to provide baseline information on community characteristics and ecosystem instability. Seven autotrophic cell types were identified over the whole sampling period. Prokaryotic cells included Synechococcus sp., a group named UNK which presented an atypical new flow cytometric signature and picoeukaryotes (PEUK). Nanophytoplankton cells were represented by 4 groups: NAN1, NAN2, NAN3 and Cryptophytes. During the first part of the survey, picophytoplankton dominated the phytoplanktonic assemblage. The mean abundance of total cells (up to 8 x 10(6) cells mL(-1)) was among the highest recorded in marine and brackish waters. Bacterial abundance and production ranged from 0.8 to 5.1 x 10(7) cells mL(-1) and from 30 to 110 mu g C L-1 h(-1). A shift from pico to nanophytoplankton abundance was observed for a few days from d 96. During this period, heterotrophic bacteria production and abundance suddenly dropped, implying a change in the functioning of the microbial loop. This shift was concomitant with a significant shrimp mortality outbreak due to Vibrio penaeicida, the etiological agent of a disease known as Syndrome 93, which affects the shrimp industry in New Caledonia. This survey suggests that flow cytometric analysis could be used for the monitoring of aquaculture systems to improve our understanding of the complex phytoplankton and bacterial dynamics of these systems and its potential influence on disease development. (c) 2010 Elsevier B.V. All rights reserved.
Aquaculture (0044-8486) (Elsevier Science Bv), 2010-12 , Vol. 310 , N. 1-2 , P. 112-121

Droits : 2010 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00029/14068/11312.pdf
DOI:10.1016/j.aquaculture.2010.10.022
http://archimer.ifremer.fr/doc/00029/14068/

Éditeur(s) : Wiley-blackwell
Résumé : Aims Exopolysaccharides (EPS) are industrially valuable molecules with numerous useful properties. This study describes the techniques used for the identification of a novel Vibrio bacterium and preliminary characterization of its EPS. Methods and Results Bioprospection in marine intertidal areas of New Caledonia followed by screening for EPS producing brought to selection of the isolate NC470. Phylogenetic analysis (biochemical tests, gene sequencing and DNADNA relatedness) permitted to identify NC470 as a new member of the Vibrio genus. The EPS was produced in batch fermentation, purified using the ultrafiltration process and analysed by colorimetry, Fourier Transform Infrared spectroscopy, gas chromatography, Nuclear Magnetic Resonance and HPLC-size exclusion chromatography. This EPS exhibits a high N-acetyl-hexosamines and uronic acid content with a low amount of neutral sugar. The molecular mass was 672x103Da. These data are relevant for possible technological exploitation. Conclusions We propose the name Vibrio neocaledonicus sp. nov for this isolate NC470, producing an EPS with an unusual sugar composition. Comparison with other known polymers permitted to select applications for this polymer. Significance and Impact of the Study This study contributes to evaluate the marine biodiversity of New Caledonia. It also highlights the biotechnological potential of New Caledonia marine bacteria.
Journal Of Applied Microbiology (1364-5072) (Wiley-blackwell), 2013-06 , Vol. 114 , N. 6 , P. 1702-1712

Droits : 2013 The Society for Applied Microbiology
http://archimer.ifremer.fr/doc/00144/25501/24036.pdf
DOI:10.1111/jam.12184
http://archimer.ifremer.fr/doc/00144/25501/

Éditeur(s) : Elsevier
Résumé : Vibrio tapetis is the marine bacterium responsible for the brown ring disease (BRD) affecting die manila clam, Ruditapes philippinarum. Identification of V tapelis has been previously performed using biochemical criteria and serological procedures. All of these methods are time consuming and ill-adapted to individual screening. This study describes an oligonucleotidic probe (Vt446) and two PCR primers, deduced from the 16S rDNA sequence, allowing a fast and specific V tapetis identification using dot blot hybridisation and species-specific primed PCR (SSP-PCR). The probe and primers have been tested on 60 strains, including referenced Vibrio sp., Gram negative and positive bacteria, marine bacteria samples and isolated clam bacteria. For all the 19 V tapetis strains, the results of PCR assays consistently corroborated those of the agglutination tests. The detection limit was estimated to be 10(2) CFU ml(-1). The SSP-PCR method has resulted in V tapetis detection in larvae, m diseased clams, and in asymptomatic broodstock clams that later developed BRD. In conclusion, the two SSP-PCR primers were useful for direct and fast identification of V tapetis strains isolated in clams, and are well suited for the screening of individual R. philippilnarum broodstock clams and larvae from the hatchery. (C) 2005 Elsevier B.V. All rights reserved.
Aquaculture (0044-8486) (Elsevier), 2006-03 , Vol. 253 , N. 1-4 , P. 25-38

Droits : 2005 Elsevier B.V. All rights reserved
http://archimer.ifremer.fr/doc/2006/publication-1692.pdf
DOI:10.1016/j.aquaculture.2005.03.047
http://archimer.ifremer.fr/doc/00000/1692/

Éditeur(s) : Elsevier
Résumé : Vibriosis is a major disease problem in shrimp aquaculture, affecting all developmental stages, from larvae in hatchery tanks to juveniles and broodstock in growout ponds. However, bacterial strains responsible for vibriosis in the successive stages are usually considered to be different, and virulence specificity has been reported both at the species and at the stage levels. The so-called « Syndrome 93 » is a seasonal juvenile vibriosis caused by Vibrio penaeicida which affects Penaeus stylirostris in growout ponds and broodstock tanks in New Caledonia. This pathology does not cause any mortality in hatchery or nursery phases. An experimental infection design using balneation of postlarvae and early juveniles in V. penaeicida suspensions was used to evaluate the developmental stage at which shrimp become sensitive to this vibriosis. We demonstrated that the acquisition of susceptibility to this pathogen is very sudden and correlated with the acquisition of the definitive rostral formula, and from this draw conclusions regarding virulence mechanisms of V. penaeicida in P. stylirostris.
Aquaculture (Elsevier), 1998-12 , Vol. 169 , N. 3-4 , P. 291-296

Droits : 1998 Elsevier Science B.V. All rights reserved
http://archimer.ifremer.fr/doc/1998/publication-383.pdf
DOI:10.1016/S0044-8486(98)00380-9
http://archimer.ifremer.fr/doc/00000/383/