Cloning and characterization of neoplasia-related genes in flat oyster Ostrea edulis

Bonamiosis and disseminated neoplasia (DN) are the most important diseases affecting cultured flat oysters Ostrea edulis in Galicia (NW Spain). Previous research using suppresive substraction hybridisation that had been performed addressing the molecular basis of DN as well as the induction and development of the disease in oysters, yielded the whole open reading frame of nine genes: XBP-1, RACK, NDPk, C1qTNF, RPA3, SAP18, p23, ubiquitin and ferritin. These nine genes were characterized in this study. The phylogenetic relationships for each gene were studied using minimum-evolution methods. Quantitative-PCR assays were also developed to analyse the modulation of the expression of these genes by bonamiosis and disseminated neoplasia. Gene expression profiles were studied in haemolymph cells and in various organs (gill, gonad, mantle and digestive gland) of oysters affected by bonamiosis, disseminated neoplasia, both diseases and in non-affected oysters (control). The expression of XBP-1, NDPk, RPA3, SAP18 and ferritin increased in haemolymph cells of oysters with heavy bonamiosis. The expression of C1qTNF; SAP18 and p23 increased in haemolymph cells of oysters with DN. The expression of XBP-1, RACK, NDPk, RPA3 and p23 significantly increased in haemolymph cells of oysters affected by both diseases. There were changes in the expression of a number of genes in different organs depeding on disease stage: RACK expression increased in gills of oysters with bonamiosis, XBP-1 increased in mantle and digestive organs of oysters with light DN and RPA3 expression increased in gonads of oysters with heavy bonamiosis and heavy neoplasia.