Plant & Animal Genomes XIII Conference

January 15-19, 2005
Town & Country Convention Center
San Diego, CA

Gene Expression In Eastern Oysters, Crassostrea virginica, At Early Time Points After Experimental Infection With The Parasite Perkinsus marinus.

Luisa Villamil , Marta Gomez-Chiarri

  Department of Fisheries, Animal and Vet Sci, University of Rhode Island, 20A Woodward Hall, Kingston, RI 02881, USA

Perkinsus marinus is a protozoan parasite responsible for Dermo disease, which causes widespread mortality of the Eastern oyster, Crassostrea virginica. Knowledge on the oyster defense systems and on the mechanisms used by pathogens to evade oyster responses is crucial to develop strategies for promoting disease resistance and managing epizootics. In order to elucidate the molecular mechanisms underlying early responses of the oyster to parasitic infection, we constructed suppression subtractive hybridization libraries with RNA of hemocytes from oysters experimentally infected with either P. marinus or artificial seawater. We have screened about 400 clones from these libraries and identified 170 genes differentially expressed at early time points (4 – 48 hours) after experimental infection with P. marinus. Sequence analysis indicates an unusually large proportion of unknown genes in the library (82% for the upregulated library) showing no significant matches with the genetic databases. Known sequences included genes involved in metabolism (arginine kinase, LDL receptor; NADH dehydrogenase), gene regulation and immunity (histone H4, QM protein, lipooxigenase), homeostasis and immunity (metallothionein, cavortin), and ribosomal and mitochondrial genes. The patterns of expression of selected genes were further studied in hemocytes and other tissues of oysters experimentally and naturally infected with P. marinus. The identification of genes involved in the early response of oysters to parasitic infection provides a starting point for dissecting the mechanisms of immunity in oysters.