Annotation and analysis of expressed sequence tags (ESTs) from Chinese sturgeon (Acipenser sinensis) pituitary cDNA library

Chinese sturgeon Acipenser sinensis belongs to the family Acipenseridae, an ancient species of actinopterygian fishes. In order to advance molecular research on its reproduction, ontogenetic development, we were seeking for genomic information in the NCBI expressed sequence tag (EST database). We found 3384 indentified cDNA sequences which were assembled into 861 unigenes. Blast analysis revealed 301 unigenes shared high similarity with genes in the public databases, and these were classified into three groups: 202 known genes, 81 putative genes and 8 unknown genes. The remainder (560 genes) had no significant match to any protein sequence. Further, 255 unigenes and 333 unmatched unigenes were annotated with Gene Ontology (GO), which could be classified into cellular component, molecular function, and biological process. Among the known genes, the hormone genes pomc A (proopiomelanocortin), pomc B, GtH alpha I subunit (gonadotropin hormone), GtH alpha II subunit and GH (growth hormone) were present in this library. Comparison of the Chinese sturgeon proteins (GH, GtH alpha subunit and POMC) to proteins of other species showed higher levels of homology among sturgeon species. We performed five hormone related genes including GnRHRI (gonadotropin-releasing hormone receptor I), cpH (carboxypeptidase H), ppiB (peptidylprolyl isomerase B), stmn3 (stathmin-like 3), 7B2 (neuroendocrine protein 7B2), and four novel genes (contig 192, 177, 170 and 168) a semi-quantitative RT-PCR on different tissues from Chinese sturgeon.