柔嫩艾美尔球虫EST序列中SSR的获取及分析

对柔嫩艾美尔球虫EST—SSR进行生物信息学分析，共获取Eimeria tenella EST序列34074条，总长度为16．45Mb，小于12bpSSR的ESTs达7651条，从中获得SSR序列19576条、总长度为0．35Mb，EST—SSRs的频率是48．00％，平均相隔S40bp出现一个长度不小于12bp的SSR。在E．tenella的核苷酸重复基元中，2、3、4、5、6和7bp重复序列在基因组中出现的种类分别有11种472条、49种14710条、31种525条、13种25条、21种43条和15种400条，3碱基重复序列是最丰富的重复单元，占总数的75．14％。各种SSRs中富含G、C碱基的重复单元以GCA出现频率最多（28．63％），次为AGC（17．59％），GCT（8．76％），TGC（7．62％），CTG（7．15％）。

Bioinformatics Analysis of Microsatelltes from EST in Eimeria tenella Genome

The microsatellites DNA or simple sequence repeats （SSRs） from expressed sequence tags（ESTs） of Eimeria tenella were investigated. ESTs of Eimeria teneUa were screen and analyze. A total of 34 074 ESTs of E. tenella with the length of 16.45Mb were searched and 19, 576 EST- SSRs with the length of repeat more than 12bp were distributed in 7 651 ESTs, which the length of EST- SSRs was 0.35Mb and the frequency of the non- redundant ESTs was about 48.00%. The frequency of SSRs was estimated approximately 1/840 kb. The frequencies of different SSR types （ di - , tri - , tetra - , and penta - nucleotide repeats） were 11,49,31,13,21 and 15 kinds, respectively. The most abundant microsatellite was trinucleotide repeat, the number was 14,710（75.14% in total EST- SSR of E. tenella）. The （G ＋ C） - rich motifs are the most common among trinucleotides in all repeat motifs, Which the high frequency of SSRs is GCA （28.63%）, followed by AGC （17.59%）, the GCT （8.76%）, TGC （7.62%）,CTG （7.15%）.