Increasing genomic information in bivalves through new EST collections in four species: development of new genetic markers for environmental studies and genome evolution

The generation of EST information is an essential step in the genomic characterisation of species. In the context of the European Network Marine Genomics, a common goal was to significantly increase the amount of ESTs in commercial marine mollusk species and more specifically in the less studied but ecologically and commercially important groups, such as mussel and clam genera. Normalized cDNA libraries were constructed for four different relevant bivalves species (Crassostrea gigas, Mytilus edulis, Ruditapes decussatus and Bathymodiolus azoricus), using numerous tissues and physiological conditions. In this paper, we present the analysis of the 13,013 expressed sequence tags (ESTs) generated. Each EST library was independently assembled and 1300-3000 unique sequences were identified in each species. For the different species, functional categories could be assigned to only about 16 to 27% of ESTs using the GO annotation tool. All sequences have been incorporated into a publicly available database and form the basis for subsequent microarray design, SNP detection and polymorphism analysis, and the placement of novel markers on genetic linkage maps. © 2007 Elsevier B.V. All rights reserved.
The research presented in this paper was funded by the European Commission through the Marine Genomics Network of Excellence (GOCE-CT-2004-505403). C.S. wishes to acknowledge additional funding from the “Ramón y Cajal” Program and grants AGL2003–04143 and AGL2006–08944 from the Spanish government.