Est project in teleosts: an approach for molecular biomarker research.

The scarcity of the genomic resources for some fish species, in spite of their commercial interest, could retard the positive effects that modern biotechnology can offer to aquaculture industry. Then an effort should be made to reduce, as far as it concerns genomic resources, the gap that separates farming species from “model organisms". In this thesis I have reported the construction and the analysis of eight cDNA libraries obtained from different tissues of three teleosts: D. labrax, P. fluviatilis and T. thynnus. A total of 13618 clones were generated from Expressed Sequence Tags and these were searched for homology in the GeneBank with BlastN and BlastX programs. In order to understand the molecular composition of the tissues analyzed, the expression profiles of the identified clones in these cDNA libraries were analyzed. Therefore, in this study have been identified 293 genes expressed in the liver of D. labrax, 258 genes expressed in three libraries (liver, liver vs brain and brain vs liver) of P. fluviatilis and 2094 genes expressed in four libraries (ovary, testis, liver and normalized ovary) of T. thynnus. EST cataloguing and profiling of these teleosts will set the basis for functional genomic research in these species, but will also serve for comparative and environmental genomics, for the identification of polymorphic markers useful, for example, to survey the disease resistance of fish, for the discovery of new molecular markers of exposure.