Construction of cDNA libraries from mantle and kidney of Japanese scallop (Mizuhopecten yessoensis) and ESTs analysis

The cDNA libraries of mantle and kidney of Japanese scallop(Mizuhopecten yessoensis)were constructed with SMART cDNA library construction kit.The mantle and kidney libraries have high library titers of 2.30×106 and 1.20×106 CFU/mL,respectively.The recombined efficiency of each cDNA library exceeds 98%,with an average insert size of 1 kb.Total 4 009 clones from two libraries were randomly picked out and sequenced from the 5′end using a T7 universal primer,and 3 884 raw sequences of the ESTs were obtained and then assembled into 2 007 unigenes including 363 contigs and 1 644 singletons.These genes exhibited homology with those having known functions.Many genes were related to immune functions,such as lipase,C-type lectin,superoxide dismutase,goose- type lysozyme,serine protease inhibitor and big defensin.Sixty-nine microsatellite-containing ESTs were identified from the 2 007 unigenes by using the online bioinformatics software SSRIT.Based on the flanking sequences of the microsatellite loci,40 pairs of microsatellite primers were designed.The successful construction of cDNA libraries from Japanese scallop made the bases of further analysis of ESTs functional gene discovery,and cloning and screening polymorphic EST-SSR primers.