Expressed sequence tags (EST) identify genes preferentially expressed in catfish chemosensory tissues

Expressed sequence tags (ESTs) for the catfish (Ictalurus punctatus) were identified and characterized by shotgun sequencing coupled to Northern analysis. We have identified and characterized a number of cDNA clones from a catfish olfactory mucosal library that show differential tissue expression including several that are enriched in chemosensory tissue. Among the novel cDNA clones studied were an olfactory specific beta-tubulin and a novel member of the S-100 family of calcium-binding proteins that is highly expressed in barbel, olfactory mucosa and gill, but not in brain. Several clones of low abundance mRNAs were also identified, including one manifesting a basic-helix-loop-helix (b-HLH) motif that is typical of many transcription factors. Additional cDNA clones whose mRNAs are differentially expressed, but are of unknown function, were also obtained. These results demonstrate the case with which novel gene products enriched in chemosensory tissues can be identified.