Generation, annotation, and analysis of ESTs from hemocyte of the bloody clam, Tegillarca granosa

Tegillarca granosa, bloody clam are valuable resource and extensive culture bivalve in China. In contrast to other cultured mollusca, very few genomic resources are available in this species. In an effort to identify clam genes involved in immunity, growth and hemoglobins, a normalized full-length cDNA library were constructed from hemocytes of the bloody clam. 2278 ESTs from 5′ ends of the cDNA clones representing 1501 unigenes with an average length of 459 bp were obtained from library. Cluster analysis of these ESTs identified 1501 unique sequences containing 173 contigs and 1328 singletons. Among the sequences that matched known genes, based on comparisons with the NCBI non-redundant database, the unigene were clustered into six categories, 142 (29.0%) were related to metabolism, 128 (26.3%) were related to cell structure/motility, 94 (19.2%) were related to gene/protein expression, 61 (12.5%) were related to cell signaling/communication, 50 (10.2%) were related to cell/organism immune, and 14 (2.8%) were related to cell division. All contigs and singlets were compared to the public protein database using BLASTx, and annotations and descriptions of interested genes related to immunity, growth or hemoglobin. These genome resources provide a significant number of ESTs for gene discovery and development of microarrays for gene expression.