SEQUENCE ANALYSIS OF 1500 CDNA CLONES FROM THE PACIFIC OYSTER C. gigas

¹ Department of Molecular Biology, Keio University School of Medicine, Shinjuku, Tokyo

² International Center for Aquaspecies Genomics, Miyazu, Kyoto

³ Department of Medical Genetics, Kyorin University School of Health Sciences, Hachioji, Tokyo

⁴ Department of Physiology, Dokkyo University School of Medicine, Shimotuga, Tochigi

It has been known that the oviparous oysters change sex during the interval between two breeding seasons. As a step toward understanding the genetic mechanisms of sex differentiation and change, we constructed cDNA libraries of the Pacific oyster C. gigas, particularly from gonads representing different stages of sex differentiation. We performed DNA sequencing of over 1500 cDNA clones for both 3'- and 5'-directions. Homology search of nearly 3000 sequence entries with BLAST revealed a number of genes which are homologous to known genes from other species. Typical examples are genes for tubulin, actin and mitochondrial proteins such as cytochrome b and NADH dehydrogenase. Others include genes for protein synthesis machinery, nuclear factors, membrane proteins, heat shock proteins, protein kinases, protein phosphatases, growth-related proteins and DNA replication. There are also many sequences which have no homology with any known genes. The sequence information in general should be useful for gene identification and QTL mapping. We are in the process of isolating full-length cDNA clones using sequences with unknown nature in order to find candidate genes for sex differentiation of oyster.