Bai Zhiyi, Yin Yuxin, Hu Songnian, Wang Guiling, Zhang Xiaowei, Li Jiale
Key Laboratory of Aquatic Genetic Resources and Aquacultural Ecology Certificated by Ministry of Agriculture, E-Institute of Shanghai Universities, Shanghai Ocean University, Shanghai, China.
Mar Biotechnol (NY). 2009 Jul-Aug;11(4):520-30. doi: 10.1007/s10126-008-9163-0. Epub 2008 Nov 28.
Triangle sail mussel (Hyriopsis cumingii) is the most important mussel species commercially exploited for freshwater pearl production in China. However, its genome research is still at the infantry. Genomic resources for this species are largely not available. The objectives of this study was to generate expressed sequence tags from a hemocyte cDNA library, to identify genes involved in defense mechanisms, and to identify polymorphic markers from the expressed sequence tag (EST) resources for genetic analysis. A total of 5,290 ESTs were sequenced, obtaining 481 contigs and 1,165 singletons. BLAST similarity analysis indicated almost half (46.5%) of these ESTs were homologs of known genes while 53.5% were transcripts of unknown identities. Based on sequence similarities, 50 genes were identified as putative genes involved in immune and defense functions such as hemocyte immune process, stress proteins, adhesive proteins, proteases and protease regulators, antimicrobial peptides, lysosomal enzymes, cell apoptosis, and cell cycle proteins. A total of 201 microsatellites were identified from these ESTs, with 31 having sufficient flanking sequences for primer design. Polymerase chain reaction amplification was successful for 18 primer pairs and 14 of them were polymorphic. A total of 987 putative single nucleotide polymorphisms were identified including 204 transitions, 611 transversions, and 172 indels; 12 of them were involved in nine genes of defense mechanisms. These resources provide the material basis for future marker validation and genetic linkage and quantitative trait loci analysis in the freshwater pearl mussel.
三角帆蚌（Hyriopsis cumingii）是中国淡水珍珠生产中商业开发最重要的蚌类物种。然而，其基因组研究仍处于起步阶段。该物种的基因组资源在很大程度上尚未可得。本研究的目的是从血细胞cDNA文库中生成表达序列标签，鉴定参与防御机制的基因，并从表达序列标签（EST）资源中鉴定多态性标记用于遗传分析。总共对5290个EST进行了测序，获得了481个重叠群和1165个单拷贝序列。BLAST相似性分析表明，这些EST中近一半（46.5%）是已知基因的同源物，而53.5%是身份未知的转录本。基于序列相似性，50个基因被鉴定为参与免疫和防御功能的推定基因，如血细胞免疫过程、应激蛋白、粘附蛋白、蛋白酶和蛋白酶调节剂、抗菌肽、溶酶体酶、细胞凋亡和细胞周期蛋白。从这些EST中总共鉴定出201个微卫星，其中31个具有足够的侧翼序列用于引物设计。18对引物的聚合酶链反应扩增成功，其中14对具有多态性。总共鉴定出987个推定的单核苷酸多态性，包括204个转换、611个颠换和172个插入缺失；其中12个涉及九个防御机制基因。这些资源为淡水珍珠蚌未来的标记验证、遗传连锁和数量性状位点分析提供了物质基础。
