EXPRESSED SEQUENCE TAGS (EST) IDENTIFY GENES PREFERENTIALLY EXPRESSEDIN CATFISH CHEMOSENSORY TISSUES

Expressed sequence tags (ESTs) for the catfish (Ictalurus punctatus) w ere identified and characterized by shotgun sequencing coupled to Nort hern analysis. We have identified and characterized a number of cDNA c lones 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-bindin g proteins that is highly expressed in barbel, olfactory mucosa and gi ll, but not in brain. Several clones of low abundance mRNAs were also identified, including one manifesting a basic-heliu-loop-helix (b-HLH) motif that is typical of many transcription factors. Additional cDNA clones whose mRNAs are differentially expressed, but are of unknown fu nction, were also obtained. These results demonstrate the ease with wh ich novel gene products enriched in chemosensory tissues can be identi fied.