Plant & Animal Genomes XVI Conference

January 12-16, 2008
Town & Country Convention Center
San Diego, CA

Protein Clues To Marker-Assisted Selection In Oysters: QX-Disease And The Sydney Rock Oyster

Sham V. Nair¹ , Margaret Simonian¹ , Alison Kan¹ , Daniel Butt¹ , Wayne O'Connor² , David A. Raftos¹

¹  Department of Biological Sciences, Macquarie University, North Ryde, NSW 2133, Australia

²  NSW Department of Primary Industries Port Stephens Fisheries Centre Locked Bag 1, Nelson Bay, NSW 2315, Australia

The Sydney rock oyster, Saccostrea glomerata, is susceptible to infection by the Paramyxean parasite, Marteilia sydneyi. This infection, known as QX-disease, results in extensive morbidity and eventual mortality of the oysters. QX-disease has caused widespread economic losses for farmers in the industry. The New South Wales government embarked on a program of breeding disease-resistance oysters in an effort to combat M. sydneyi infection. In this presentation, the role of the enzyme, phenoloxidase, in mediating disease resistance is discussed, as well as new evidence for the existence of additional molecules that contribute to QX-disease resistance. Proteomic profiles of hemocytes from disease-resistance bred and wild-type oysters show intriguing differences. Approximately 20 proteins are unique to QX-disease resistant oysters. Analysis of some of these proteins from resistant oysters using mass spectrometry indicated partial homology with previously characterised immune response proteins from the oysters, Crassostrea gigas and Crassostrea virginica. Others resistance-associated proteins are novel. Non-metric multidimensional scaling and clustering analyses of the expression patterns of hemocyte proteins revealed clear distinctions between wild-type oysters and all of the resistant lines. The proteomic profiles of most QX resistant oysters clustered tightly together and there was a clear progression from wild-type, through the various generations of resistance-bred oysters. This is consistent with continuing selection of QX disease resistance. Overall, the data suggest that numerous genetic factors contribute to QX-disease resistance in Sydney rock oysters and that proteomic analysis is a useful way of identifying disease resistant oysters for selective breeding.