Characterisation and genetic polymorphism of metallothionein gene CgMT4 in experimental families of Pacific oyster Crassostrea gigas displaying summer mortality

Abstract

Summer mortality events have been observed in Pacific oyster Crassostrea gigas for several decades. This paper examines the selective pressure exerted by summer mortality on the polymorphism of a newly identified oyster metallothionein gene. CgMT4 cDNA and genomic sequences were obtained. CgMT4 was studied in two generations of oysters reared in three sites on the French Atlantic coast, using single strand conformation polymorphism analysis. Four alleles were detected. Individuals carrying genotype MT4-CD seem to have higher susceptibility to summer risk conditions. The MT4 gene could be a potential new genetic marker for susceptibility; further validation studies are recommended.

Keywords::

• Pacific oyster
• metallothionein
• susceptibility
• genotypes
• selection

Acknowledgments

Authors are grateful to Jean-François Samain, Pierre Boudry, Lionel Dégremont and the staff of IFREMER La Tremblade for producing the oysters, and Helen McCombie for improving the English.

Declaration of interest

This work was financially supported by the inter-regional program MOREST (Summer Mortality of juvenile oysters Crassostrea gigas, Grant number 02-2-500022), the PolyGIGAS program of the Bureau des Ressources Génétiques (n° 05/5210 460/YF) and the Marine Genomics Europe Network.