Identification of the up-regulated expression genes in hemocytes of variously colored abalone (Haliotis diversicolor Reeve, 1846) challenged with bacteria

SummaryVariously colored abalone (Haliotis diversicolor Reeve, 1846), which is an important commercial aquatic species and has been widely cultured, frequently suffers from bacterial infection. Knowledge of the defense mechanism in this animal is still lacking and, so far few genes related to immune responses in abalones have been reported. In order to isolate differentially expressed genes in H. diversicolor challenged with bacteria, a forward suppression subtractive hybridization (SSH) cDNA library was constructed from their hemocytes and the up-regulated genes were identified. A total of 435 clones in the SSH library were sequenced and 111 genes were recognized based on BLAST searches in NCBI and were categorized in association with different biological processes using AmiGO against the Gene Ontology database. Of the 111 cDNAs, 86 genes were identified for the first time in H. diversicolor. The up-regulated cDNAs screened in the SSH library were validated using quantitative real-time PCR and 78 genes showed differential expression patterns. A total of 34 genes were confirmed to be distinctly up-regulated in abalones after bacterial challenge, encoding proteins involved in cellular metabolic processes; cellular component organization and biogenesis; signal transduction and biological regulation; immune defense and response to stimuli; other functions and unknown functions. This is the first report to unveil multiple up-regulated genes with differential expression patterns involving various cellular processes in bacterially challenged H. diversicolor. The data obtained from this study will provide new insights into the immune mechanism of H. diversicolor and facilitate future study of target genes involved in the response to invading microorganisms.