Whole-Genome Sequence of Pseudoalteromonas sp. NC201, a Probiotic Strain for Litopenaeus stylirostris Hatcheries in New Caledonia

Sorieul L, Rückert C, Al-Dilaimi A, et al. Whole-Genome Sequence of Pseudoalteromonas sp. NC201, a Probiotic Strain for Litopenaeus stylirostris Hatcheries in New Caledonia. Microbiology resource announcements. 2019;8(34): e00477-19.The marine bacterium Pseudoalteromonas sp. strain NC201 has shown probiotic potential in Litopenaeus stylirostris rearing. In this study, the complete genome of NC201 was sequenced. This genome consists of a chromosome (4.13Mb) and a chromid (1.24Mb). The genome contains gene clusters coding for antibacterial peptides and secondary metabolites. Copyright © 2019 Sorieul et al

Generation and analysis of a 29,745 unique Expressed Sequence Tags from the Pacific oyster (Crassostrea gigas) assembled into a publicly accessible database: the GigasDatabase

Background: Although bivalves are among the most-studied marine organisms because of their ecological role and economic importance, very little information is available on the genome sequences of oyster species. This report documents three large-scale cDNA sequencing projects for the Pacific oyster Crassostrea gigas initiated to provide a large number of expressed sequence tags that were subsequently compiled in a publicly accessible database. This resource allowed for the identification of a large number of transcripts and provides valuable information for ongoing investigations of tissue-specific and stimulus-dependant gene expression patterns. These data are crucial for constructing comprehensive DNA microarrays, identifying single nucleotide polymorphisms and microsatellites in coding regions, and for identifying genes when the entire genome sequence of C. gigas becomes available. Description: In the present paper, we report the production of 40,845 high-quality ESTs that identify 29,745 unique transcribed sequences consisting of 7,940 contigs and 21,805 singletons. All of these new sequences, together with existing public sequence data, have been compiled into a publicly-available Website http://public-contigbrowser.sigenae.org:9090/Crassostrea_gigas/index.htm l. Approximately 43% of the unique ESTs had significant matches against the SwissProt database and 27% were annotated using Gene Ontology terms. In addition, we identified a total of 208 in silico microsatellites from the ESTs, with 173 having sufficient flanking sequence for primer design. We also identified a total of 7,530 putative in silico, single-nucleotide polymorphisms using existing and newly-generated EST resources for the Pacific oyster. Conclusion: A publicly-available database has been populated with 29,745 unique sequences for the Pacific oyster Crassostrea gigas. The database provides many tools to search cleaned and assembled ESTs. The user may input and submit several filters, such as protein or nucleotide hits, to select and download relevant elements. This database constitutes one of the most developed genomic resources accessible among Lophotrochozoans, an orphan clade of bilateral animals. These data will accelerate the development of both genomics and genetics in a commercially-important species with the highest annual, commercial production of any aquatic organism

Expression and localization of Aquaporin 1a in the sea-bass (Dicentrarchus labrax) during ontogeny

The successful establishment of a species in a given habitat depends on the ability of each of its developing stages to adapt to the environment. In order to understand this process we have studied the adaptation of a euryhaline fish, the sea-bass Dicentrarchus labrax, to various salinities during its ontogeny. The expression and localization of Aquaporin 1a (AQP1a) mRNA and protein were determined in different osmoregulatory tissues. In larvae, the sites of AQP1a expression are variable and they shift according to age, implying functional changes. In juveniles after metamorphosis (D32–D48 post-hatch, 15–25mm) and in pre-adults, an increase in AQP1a transcript abundance was noted in the digestive tract, and the AQP1a location was observed in the intestine. In juveniles (D87–D100 post-hatch, 38–48 mm), the transcript levels of AQP1a in the digestive tract and in the kidney were higher in sea water (SW) than at lower salinity. These observations, in agreement with existing models, suggest that in SW-acclimated fish, the imbibed water is absorbed via AQP1a through the digestive tract, particularly the intestine and the rectum. In addition, AQP1a may play a role in water reabsorption in the kidney. These mechanisms compensate dehydration in SW, and they contribute to the adaptation of juveniles to salinity changes during sea-lagoon migrations. These results contribute to the interpretation of the adaptation of populations to habitats where salinity varies.Publisher PDFPeer reviewe

Écophysiologie comparée de l adaptation ontogénétique à la salinité chez la daurade Sparus aurata et le loup de mer (bar) Dicentrarchus labrax

Cette étude a associé la nano-osmométrie et la biologie cellulaire et moléculaire pour explorer les mécanismes ontogénétiques d'adaptation de ces poissons à la salinité Ils acquièrent les capacités osmorégulatrices de l'adulte en plusieurs étapes, dont l'ouverture de la bouche et la métamorphose. La mise en place de l'ATPase Na+/K+ (NKA), du cotransporteur Na+/K+/2Cl- (NKCC) et du canal à chlore CFTR, a été suivie durant l'ontogenèse selon la salinité. A l'éclosion, les protéines sont localisées dans les ionocytes tégumentaires et intestinaux. Le tégument dès l'éclosion et les branchies dès leur formation, interviennent dans la sécrétion ionique en eau de mer (EM) : la NKA et le NKCC sont basolatéraux, et le CFTR apical. Au cours de l'ontogenèse, le tube digestif accroît sa fonction osmorégulatrice ; le tégument est relayé par les branchies en formation. Au niveau du rein, les protéines apparaissent plus tardivement, chez les prélarves de D. labrax et les larves de S. aurata. Chez les juvéniles, la localisation, l'expression et la quantité des 3 protéines ont été étudiées en fonction de la salinité, EM, eau douce (ED) et eau à 5 (EMD). Les branchies sont le site osmorégulateur majeur avec les plus fortes expressions protéiques. Les localisations branchiales suggèrent un basculement de la fonction de sécrétion ionique en EM à celle d'absorption ionique en EMD/ED. Le tube digestif est impliqué à la fois dans la régulation osmotique quelles que soient la salinité et l'espèce, et dans la régulation acido-basique chez D. labrax en ED et S. aurata en EM et EMD. Les ionocytes rénaux favorisent l'absorption ionique via la NKA et le NKCC (et le CFTR chez S. aurata). Les mécanismes physiologiques et cellulaires mis en évidence contribuent à comprendre les adaptations des 2 espèces à la salinité au cours du développement. Elles leur permettent d'effectuer des migrations ontogénétiques entre des milieux de salinité plus ou moins variable, en particulier entre la mer et les estuaires ou lagunes.This integrative study of the ecophysiology of the sea bass and sea bream has used nano-osmometry and cell and molecular biology to decipher the mechanisms of ontogenetic adaptation of these teleosts to their media. Adult levels of osmoregulatory capacity occur over several steps, particularly at mouth opening and after metamorphosis. The occurrence of Na+/K+ ATPase (NKA), of the Na+/K+/2Cl- (NKCC) cotransporter and of the CFTR chloride channel has been followed during the ontogeny of both species and according to salinity. At hatching, these proteins are localized in the integumentary ionocytes and in the digestive tract. The integument, from hatching, and the gills when they develop, are involved in ionic secretion in sea water (SW): NKA and NKCC are basolateral, and CFTR is apical. During ontogeny, the osmoregulatory function increases in the digestive tract; it shifts from the integument to the developing gills. In the kidney, the proteins occur later, in prelarvae of D. labrax and in larvae of S. aurata, suggesting its late involvement in ionic regulation. In juveniles, the localization, expression and quantity of the different proteins have been studied in SW, fresh water (FW) and in a 5 medium (DSW). Gills are the major site of osmoregulation, where protein expressions are highest. The gill protein locations suggest a shift from ionic secretion in SW to ionic absorption in FW and DSW. The digestive tract is involved in osmotic regulation at all salinities in both species, and also in acid-base regulation in D. labrax in FW, and in S. aurata in SW and DSW. Renal ionocytes are involved in ionic absorption via NKA and NKCC (and CFTR in S. aurata). The physiological and cellular mechanisms revealed in this study contribute to the understanding of the adaptations of both species to salinity during development. They allow ontogenetic migrations between media with different salinity regimes, particularly between the sea and estuaries or lagoonsMONTPELLIER-BU Sciences (341722106) / SudocSudocFranceF

Monoclonal antibodies against sporangia and spores of Marteilia sp. (Protozoa: Ascetospora)

Digestive glands of mussels Mytilus edulis from Brittany, France, infected with Marteilia sp. (Ascetospora) were used to purify the parasite. A modification of a previously used purification protocol increased purification efficiency, permitting sporangial primordia and sporangia of Marteilia sp. to be obtained. Mouse (Balb/c) monoclonal antibodies were generated against this parasite. From the fusion, 26 monoclonal antibodies against Marteilia sp. were obtained. Antibodies from 6 clones reacted only with Marteilia sp. cells and not with normal host tissues. Four of these antibodies (1/1-3, 3/1-1, 4/1-1 and 6/2-3) reacted with the sporangia wall and two with the spore cytoplasm (9/1-1 and 12/5-1). Antibodies cross-reacted with Marteilia refringens from Mytilus galloprovincialis obtained in the Ria de Vigo, Spain

Microbial biomarker detection in shrimp larvae rearing water as putative bio-surveillance proxies in shrimp aquaculture

Background Aquacultured animals are reared in water hosting various microorganisms with which they are in close relationships during their whole lifecycle as some of these microorganisms can be involved in their host’s health or physiology. In aquaculture hatcheries, understanding the interactions existing between the natural seawater microbiota, the rearing water microbiota, the larval stage and the larval health status, may allow the establishment of microbial proxies to monitor the rearing ecosystems. Indeed, these proxies could help to define the optimal microbiota for shrimp larval development and could ultimately help microbial management. Methods In this context, we monitored the daily composition of the active microbiota of the rearing water in a hatchery of the Pacific blue shrimp Penaeus stylirostris. Two distinct rearing conditions were analyzed; one with antibiotics added to the rearing water and one without antibiotics. During this rearing, healthy larvae with a high survival rate and unhealthy larvae with a high mortality rate were observed. Using HiSeq sequencing of the V4 region of the 16S rRNA gene of the water microbiota, coupled with zootechnical and statistical analysis, we aimed to distinguish the microbial taxa related to high mortality rates at a given larval stage. Results We highlight that the active microbiota of the rearing water is highly dynamic whatever the larval survival rate. A clear distinction of the microbial composition is shown between the water harboring heathy larvae reared with antibiotics versus the unhealthy larvae reared without antibiotics. However, it is hard to untangle the effects of the antibiotic addition and of the larval death on the active microbiota of the rearing water. Various active taxa of the rearing water are specific to a given larval stage and survival rate except for the zoea with a good survival rate. Comparing these communities to those of the lagoon, it appears that many taxa were originally detected in the natural seawater. This highlights the great importance of the microbial composition of the lagoon on the rearing water microbiota. Considering the larval stage and larval survival we highlight that several genera: Nautella, Leisingera, Ruegerira, Alconivorax, Marinobacter and Tenacibaculum, could be beneficial for the larval survival and may, in the rearing water, overcome the r-strategist microorganisms and/or putative pathogens. Members of these genera might also act as probiotics for the larvae. Marivita, Aestuariicocccus, HIMB11 and Nioella, appeared to be unfavorable for the larval survival and could be associated with upcoming and occurring larval mortalities. All these specific biomarkers of healthy or unhealthy larvae, could be used as early routine detection proxies in the natural seawater and then during the first days of larval rearing, and might help to manage the rearing water microbiota and to select beneficial microorganisms for the larvae

The effects of acute transfer to freshwater on ion transporters of the pharyngeal cavity in European seabass (Dicentrarchus labrax)

International audienceGene expression of key ion transporters (the Na+/K+-ATPase NKA, the Na+, K+-2Cl− cotransporter NKCC1, and CFTR) in the gills, opercular inner epithelium, and pseudobranch of European seabass juveniles (Dicentrarchus labrax) were studied after acute transfer up to 4 days from seawater (SW) to freshwater (FW). The functional remodeling of these organs was also studied. Handling stress (SW to SW transfer) rapidly induced a transcript level decrease for the three ion transporters in the gills and operculum. NKA and CFTR relative expression level were stable, but in the pseudobranch, NKCC1 transcript levels increased (up to 2.4-fold). Transfer to FW induced even more organ-specific responses. In the gills, a 1.8-fold increase for NKA transcript levels occurs within 4 days post transfer with also a general decrease for CFTR and NKCC1. In the operculum, transcript levels are only slightly modified. In the pseudobranch, there is a transient NKCC1 increase followed by 0.6-fold decrease and 0.8-fold CFTR decrease. FW transfer also induced a density decrease for the opercular ionocytes and goblet cells. Therefore, gills and operculum display similar trends in SW-fish but have different responses in FW-transferred fish. Also, the pseudobranch presents contrasting response both in SW and in FW, most probably due to the high density of a cell type that is morphologically and functionally different compared to the typical gill-type ionocyte. This pseudobranch-type ionocyte could be involved in blood acid-base regulation masking a minor osmotic regulatory capacity of this organ compared to the gills

Monoclonal antibody against a gill Rickettsiales-like organism of Pecten maximus (Bivalvia): application to indirect immunofluorescence diagnosis

Using hybridoma technology, monoclonal antibodies (MABs) were prepared against a Rickettsiales-like organism (RLO) from the gills of the Saint-Jacques scallop Pecten maximus. The 5D7 MAB was then selected as a specific reagent suitable for an indirect immunofluorescence assay (IIFA) and evaluated for RLO diagnosis on P. maximus gill smears. Monoclonal antibody 5D7 showed no cross-reactivity with an RLO associated with a related pectinid species Chlamys opercularis

Cellular and molecular hemocyte responses of the Pacific oyster, Crassostrea gigas, following bacterial infection with Vibrio aestuarianus strain 01/32

International audienceThe strategies used by bacterial pathogens to circumvent host defense mechanisms remain largely undefined in bivalve molluscs. In this study, we investigated experimentally the interactions between the Pacific oyster (Crassostrea gigas) immune system and Vibrio aestuarianus strain 01/32, a pathogenic bacterium originally isolated from moribund oysters. First, an antibiotic-resistant V. aestuarianus strain was used to demonstrate that only a limited number of bacterial cells was detected in the host circulatory system, suggesting that the bacteria may localize in some organs. Second, we examined the host defense responses to V. aestuarianus at the cellular and molecular levels, using flow-cytometry and real-time PCR techniques. We showed that hemocyte phagocytosis and adhesive capabilities were affected during the course of infection. Our results also uncovered a previously-undescribed mechanism used by a Vibrio in the initial stages of host interaction: deregulation of the hemocyte oxidative metabolism by enhancing the production of reactive oxygen species and down-regulating superoxide dismutase (Cg-EcSOD) gene expression. This deregulation may provide an opportunity to the pathogen by impairing hemocyte functions and survival. These findings provide new insights into the cellular and molecular bases of the host-pathogen interactions in C. gigas oyster