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Open Access Research article

A hemocyte gene expression signature correlated with predictive capacity of oysters to survive Vibrio infections

Rafael Diego Rosa12, Julien de Lorgeril1, Patrick Tailliez3, Roman Bruno4, David Piquemal4 and Evelyne Bachère1*

Author Affiliations

1 1Ifremer, CNRS, Université Montpellier 2, IRD and Université Montpellier 1, UMR 5119 “Laboratoire Écologie des Systèmes Marins Côtiers, Place Eugène Bataillon, PO Box 34095, Montpellier, France

2 Université Montpellier 2, IRD,Ifremer, CNRS, and Université Montpellier 1, UMR 5119 “Laboratoire Écologie des Systèmes Marins Côtiers, Place Eugène Bataillon, PO Box 34095, Montpellier, France

3 INRA, Université Montpellier 2, UMR 1133 “Laboratoire Écologie Microbienne des Insectes et Interactions Hôte-Pathogènes, Place Eugène Bataillon, PO Box 34095, Montpellier, France

4 Skuldtech, Cap Delta, PO Box 34790, Grabels, France

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BMC Genomics 2012, 13:252  doi:10.1186/1471-2164-13-252

Published: 18 June 2012

Abstract

Background

The complex balance between environmental and host factors is an important determinant of susceptibility to infection. Disturbances of this equilibrium may result in multifactorial diseases as illustrated by the summer mortality syndrome, a worldwide and complex phenomenon that affects the oysters, Crassostrea gigas. The summer mortality syndrome reveals a physiological intolerance making this oyster species susceptible to diseases. Exploration of genetic basis governing the oyster resistance or susceptibility to infections is thus a major goal for understanding field mortality events. In this context, we used high-throughput genomic approaches to identify genetic traits that may characterize inherent survival capacities in C. gigas.

Results

Using digital gene expression (DGE), we analyzed the transcriptomes of hemocytes (immunocompetent cells) of oysters able or not able to survive infections by Vibrio species shown to be involved in summer mortalities. Hemocytes were nonlethally collected from oysters before Vibrio experimental infection, and two DGE libraries were generated from individuals that survived or did not survive. Exploration of DGE data and microfluidic qPCR analyses at individual level showed an extraordinary polymorphism in gene expressions, but also a set of hemocyte-expressed genes whose basal mRNA levels discriminate oyster capacity to survive infections by the pathogenic V. splendidus LGP32. Finally, we identified a signature of 14 genes that predicted oyster survival capacity. Their expressions are likely driven by distinct transcriptional regulation processes associated or not associated to gene copy number variation (CNV).

Conclusions

We provide here for the first time in oyster a gene expression survival signature that represents a useful tool for understanding mortality events and for assessing genetic traits of interest for disease resistance selection programs.

Keywords:
Marine invertebrate; Mollusk bivalve; Mass mortality; Transcriptome-wide analysis; Digital gene expression; Microfluidic qPCR; Survival signature; Polymorphism; Gene copy number; Survival predictive biomarkers