Digital gene expression tag profile of five development stages of pearl sac from pearl oyster Pinctada martensii reveals potential candidates contributing to nacre formation
A sequencing depth of 5 million raw tags per sample was obtained and a large number of differentially expressed genes were identified. The results of the DGE tag profile were validated by examining gene expression in a subset of genes using qRT-PCR. Gene expression profiles at different pearl sac development stages implicated that a great change in the body of the host pearl oyster was induced by the surgical implantation and achieved the maximum at 15 days. An enrichment of genes relevant to purine metabolism was obtained by KEGG pathway analysis of the genes differentially expressed between 15 and 60 days. Analyzing gene expression trends, most of the immune-related genes, such as HSP70, TLR1 and lectin, were highly expressed before 30 days. While nacre formation-related genes, such as DPT and perlucin-like protein isoformA, and some immune-related genes, such as galectin and HSP90 like protein, were highly expressed at 60 days, indicating some immune-related gene may participate in nacre formation. Furthermore, we found 286 unigenes highly expressed at 60 days. These unigenes may be potential candidates contributing to nacre formation, such as leucine-rich repeat-containing protein, secreted protein with cysteine rich repeats and Cathepsin O. Overall design: 5 different development stages Digital Gene Expression Profiling(DGE) in pearl sac were generated by deep sequencing, using Illumina hiseq-2000