EXPRESSED SEQUENCE TAGS (ESTs) ANALYSIS OF JAPANESE FLOUNDER

Laboratory of Genetics and Biochemistry, Department of Aquatic Biosciences, Tokyo University of Fisheries, Konan 4-5-7, Minato-ku, Tokyo 108-8477, Japan

Sequencing of cDNA libraries to generate large numbers of partial cDNA sequences or expressed sequence tags (ESTs) has been shown to be a powerful tool to identify homologues of reported genes of different animals and novel genes, to evaluate the gene expression profile in a given tissue, and to compare transcription levels of many genes between different tissues or cells. A cloned population of Japanese flounder, Paralichthys olivaceus, has been produced and established. Such a cloned population is very useful for molecular biological and genome analysis. Moreover, Japanese flounder is one of the most important food fish of both the fishing and aquaculture industries in Japan. We have partially sequenced 1,792 sequences of 1,374 independent cDNA clones isolated from cDNA libraries of Japanese flounder liver (350 clones), spleen (41 clones), and hirame rhabdo virus infected leukocytes (983 clones). These sequences comprise 1,254,858 base pairs of DNA sequence. The average size of the sequenced length was 700 bp. Seven hundred and eighty-seven (57.3 %) of 1,374 clones were identified as known genes using the BLAST 2.0 database. At least 67 clones were identified as putative biodefense genes or genes associated with immune response including cytokines, cytokine receptors, immunoglobulins, T cell receptors, CD3, CD8, MHC, complement components C3, C7, C8, and C9, transcription factors for immune related genes, stress protein, interferon-induced proteins, activators of immune cells, and humoral immune response proteins.