Experimental infection of Pacific oyster Crassostrea gigas spat by ostreid herpesvirus 1: demonstration of oyster spat susceptibility

In 2008 and 2009, acute mortalities occurred in France among Pacific cupped oyster, Crassostrea gigas, spat. Different hypothesis including the implication of environmental factors, toxic algae and/or pathogens have been explored. Diagnostic tests indicated that OsHV-1 including a particular genotype, termed OsHV-1 μVar, was detected in most of samples and especially in moribund oysters with the highlighting of virus particles looking like herpes viruses by TEM examination. In this study, an experimental protocol to reproduce OsHV-1 infection in laboratory conditions was developed. This protocol was based on the intramuscular injection of filtered (0.22 μm) tissue homogenates prepared from naturally OsHV-1 infected spat collected on French coasts during mortality outbreaks in 2008. Results of the experimental trials showed that mortalities were induced after injection. Moreover, filtered tissue homogenates induced mortalities whereas the same tissue homogenates exposed to an ultraviolet (UV) treatment did not induce any mortality suggesting that oyster spat mortalities require the presence of a UV sensitive agent. Furthermore, analysis of injected oyster spat revealed the detection of high amounts of OsHV-1 DNA by real-time quantitative PCR. Finally, TEM analysis demonstrated the presence of herpes virus particles. The developed protocol allowed to maintain sources of infective virus which can be useful for the development of further studies concerning the transmission and the development of OsHV-1 infection

Spatial analysis of biomineralization associated gene expression from the mantle organ of the pearl oyster Pinctada maxima

Background: Biomineralization is a process encompassing all mineral containing tissues produced within an organism. One of the most dynamic examples of this process is the formation of the mollusk shell, comprising a variety of crystal phases and microstructures. The organic component incorporated within the shell is said to dictate this architecture. However general understanding of how this process is achieved remains ambiguous. The mantle is a conserved organ involved in shell formation throughout molluscs. Specifically the mantle is thought to be responsible for secreting the protein component of the shell. This study employs molecular approaches to determine the spatial expression of genes within the mantle tissue to further the elucidation of the shell biomineralization. Results: A microarray platform was custom generated (PmaxArray 1.0) from the pearl oyster Pinctada maxima. PmaxArray 1.0 consists of 4992 expressed sequence tags (ESTs) originating from mantle tissue. This microarray was used to analyze the spatial expression of ESTs throughout the mantle organ. The mantle was dissected into five discrete regions and analyzed for differential gene expression with PmaxArray 1.0. Over 2000 ESTs were determined to be differentially expressed among the tissue sections, identifying five major expression regions. In situ hybridization validated and further localized the expression for a subset of these ESTs. Comparative sequence similarity analysis of these ESTs revealed a number of the transcripts were novel while others showed significant sequence similarities to previously characterized shell related genes

Involvement of the Cytokine MIF in the Snail Host Immune Response to the Parasite Schistosoma mansoni

We have identified and characterized a Macrophage Migration Inhibitory Factor (MIF) family member in the Lophotrochozoan invertebrate, Biomphalaria glabrata, the snail intermediate host of the human blood fluke Schistosoma mansoni. In mammals, MIF is a widely expressed pleiotropic cytokine with potent pro-inflammatory properties that controls cell functions such as gene expression, proliferation or apoptosis. Here we show that the MIF protein from B. glabrata (BgMIF) is expressed in circulating immune defense cells (hemocytes) of the snail as well as in the B. glabrata embryonic (Bge) cell line that has hemocyte-like features. Recombinant BgMIF (rBgMIF) induced cell proliferation and inhibited NO-dependent p53-mediated apoptosis in Bge cells. Moreover, knock-down of BgMIF expression in Bge cells interfered with the in vitro encapsulation of S. mansoni sporocysts. Furthermore, the in vivo knock-down of BgMIF prevented the changes in circulating hemocyte populations that occur in response to an infection by S. mansoni miracidia and led to a significant increase in the parasite burden of the snails. These results provide the first functional evidence that a MIF ortholog is involved in an invertebrate immune response towards a parasitic infection and highlight the importance of cytokines in invertebrate-parasite interactions

A genus‑wide analysis of genetic variation to guide population management, hybrid identifcation, and monitoring of invasions and illegal trade in Iguana (Reptilia: Iguanidae)

Biodiversity and wild populations are globally threatened by a wide range of actors. The genus Iguana, widely distributed throughout the Americas, is under threat by invasive species, hybridization, the global pet trade, and habitat destruction. This holds especially true for the insular lineages, with the Critically Endangered I. delicatissima having experienced a > 75% range decrease, primarily through hybridization with non-native iguanas. We collated published microsatellite data and genotyped samples from new localities to construct a distribution-wide Iguana dataset built from 190 individuals for 17 microsatellite loci. This enabled us to identify patterns of genetic differentiation within and among populations, and identify key loci and private alleles for use in conservation management. Our analyses reveal clear separation between I. delicatissima and the I. iguana complex, highlighting the power of eight key microsatellite loci for the study of hybridization dynamics. Genetic differentiation within I. delicatissima identifies four clusters that aid decision making for conservation management action. Within the I. iguana complex, we increase mainland localities by 11-fold and recover 3.5 × more alleles across all loci than previously known. Overall, we identify 112 (48% private) and 76 (25% private) alleles for mainland and island lineages, respectively. We highlight loci sets to identify (1) non-native or hybrid iguanas in insular populations and their genetic origin, and (2) genetic origin of insular iguanas in the global pet trade. Overall, we provide a reference for Iguana microsatellite loci in order to allow standardization and comparison among studies, aiding broader assessment of research and conservation hypotheses.We thank Ty Park and all donators to IguanaFest 2019 for financial support.Peer reviewe

Strong genetic isolation of the black-lipped pearl oyster (Pinctada margaritifera) in the Marquesas archipelago (French Polynesia)

The French Polynesian islands are internationally known for their black pearls, produced by culture of the black lipped pearl oyster Pinctada margaritifera. The ongoing development of hatcheries for P. margaritifera in French Polynesia poses new challenges for the industry, particularly regarding the maintenance of genetic diversity in the hatchery stocks. This emphasizes the necessity to characterize the genetic diversity and differentiation within natural and exploited populations, to carefully select putative parental populations. The present study aimed at validating the phylogenetic status and investigating genetic attributes of populations from the only two non-exploited archipelagos of French Polynesia, the Marquesas archipelago, and the Australes archipelago, never analysed before. We found that individuals from both archipelagos belonged to P. margaritifera species. However, while the Australes population was genetically similar to non-exploited populations of the Tuamotu, the Marquesas populations were highly differentiated from the rest of the populations. This differentiation cannot not be only attributed to geographic distance and aquaculture status, but likely to hydrodynamic barriers allowing vicariant events to take place. Our results add up to other studies describing the Marquesas archipelago as a hotspot for biodiversity and differentiation, with some of the highest levels of endemism and vicariance found among marine species worldwide and provide precious information on available genetic resources for the implementation of P. margaritifera selective breeding and its genetic conservation in French Polynesia

Development of TaqMan real-time PCR assays for monitoring Vibrio harveyi infection and a plasmid harbored by virulent strains in European abalone Haliotis tuberculata aquaculture

International audienceThe Gram-negative bacterium Vibrio harveyi is known to be highly pathogenic for the European abalone Haliotis tuberculata, which is a gastronomically important marine gastropod with a high commercial value. Since 1998, some particular bacterial strains are described as implicated in recurrent mortality outbreaks in French farm and field stocks of abalone. Recently, a 9.6 kb plasmid named pVCR1, was shown to be harbored by one highly V. harveyi virulent ORM4 strain suggesting its involvement in virulence phenotype. Thus, we have developed in the present study two TaqMan real-time PCR assays allowing to (i) rapidly and specifically detect, by a duplex procedure and in less than 2 h, both V. harveyi and the presence of plasmid pVCR1 from unidentified bacterial colony and to (ii) quantify both V. harveyi and the plasmid pVCR1 in the hemolymph of abalone or its surrounding seawater. Quantification curves of V. harveyi or ORM4 strain seeded in hemolymph or artificial sea water samples were equivalent showing excellent qPCR efficacies and detection level as low as 18 V. harveyi cell-equivalent genomic DNA in a PCR reaction well. This qPCR allowed us to monitor V. harveyi ORM4 strain in experimentally infected H. tuberculata. These diagnosis assays could provide powerful and useful tools to better understand the epidemiology of vibriosis caused by V. harveyi in different cultured marine species including H. tuberculata

Chemical and Genetic profiles of black kites

Chemical profiles of every sample of black kites used in the study and Genetic profile of every individuals

Data from: Preen oil chemical composition encodes individuality, seasonal variation and kinship in black kites Milvus migrans

Evidence that bird odour can encode social information that can be used in chemical communication is growing, but is restricted to a few taxonomic groups. Among birds, diurnal raptors (i.e. birds from the Accipitriformes and Falconiformes order) have always been considered as mainly relying on their visual abilities. Although they seem to have a functional sense of smell, whether their odour can convey social information has yet to be determined. Combining gas-chromatography-mass-spectrometry (GCMS) and microsatellite data, we tested whether chemical compounds from preen gland secretions can encode sex, age, individuality, seasonal differences and genetic relatedness in the gregarious accipitriform black kite Milvus migrans. While no differences in preen oil composition were found between age classes, an individual signature was detected. While a seasonal variation was found in both sexes, compounds differ between sexes in the non-breeding season. Finally, a significant correlation between chemical proximity and genetic proximity was detected in male-male dyads and male-female dyads but not in female-female dyads. Our study provides the first evidence in raptors that preen secretion can convey information that may potentially be used in individual recognition, reproductive synchronization and inbreeding avoidance, and suggests that raptors may rely upon their olfactory abilities more than previously thought. This study opens promising avenues for further studies in raptor chemical communication