长牡蛎(Crassostrea gigas)EST串联重复序列的组成和分布

Bioinformatics data mining of EST- tandem repeats of the Pacific Oyster (Crassostrea gigas)

长牡蛎（Crassostrea gigas）串联重复序列分析研究较少，为了研究其在基因组转录本的基本结构特征并为长牡蛎中遗传多样性研究中提供有益的信息，利用NCBI公共数据库中的57139条长牡蛎ESTs序列对串联重复序列结构类型、分布、丰度等进行系统比较分析。分析结果表明：1）长牡蛎EST中共有小卫星串联重复序列8392个，在大于100bp重复类型中，162～167bp含量最高；2）长牡蛎ESTSSR含量丰富，1954个位点是EST-SSR标记开发的候选资源；3）EST-SSR重复数目和重复类型在5’UTR，CDS和3＇UTR具有显著差异，CDS区承受更大的选择压力。

Large scale analysis of tandem repeats in the Pacific Oyster is underdeveloped on the level of ESTs. The analysis of tandem repeats will be useful to a variety of applications in the study of transcripts characteristics and population genetics of the Pacific Oyster. We analyzed tandem repeats in the Pacific Oyster based on 57 139 ESTs downloaded from NCBI. The major results were as follows： 1） we obtained 8 392 minisatellite sequences, which were much more widely dispersed in the repeat types of 162-167 bp （〉100bp）; 2） ESTs were abundant, and 1 954 EST-SSRs were of the potential for designing primers specific to flanking sequences; 3） the repeat counts and repeat types were significantly different for 5＇UTR, 3＇UTR, and CDS; CDS undergoes much greater selective pressure.