大黄鱼EST微卫星标记初步筛选

通过构建大黄鱼性腺线性化cDNA文库，并经测序后获得3535条EST，对其二碱基至六碱基重复序列进行筛选，共发现微卫星位点150个，占EST序列的4．24％；其中包括二碱基重复序列64条，三碱基重复序列80条，四碱基重复序列5条，五碱基重复序列1条；三碱基重复序列是最丰富的重复单元，占53．3％。在这些微卫星序列中，（TG／GT／AC／CA）n形式在二碱基重复中最为常见，（GAG／AGG／GGA／CCT）n形式在三碱基重复序列中最为常见，分别占微卫星序列总数的26％和14％。选取其中的62条微卫星序列进行引物设计、合成与多态性检测，经过PCR扩增，2．0％的琼脂糖凝胶电泳检测，获得呈多态性微卫星引物8对，多态率为12．9％。本研究为开发大黄鱼EST微卫星分子标记和大黄鱼基因编码区微卫星的功能研究提供有价值的信息。

A preliminary study on microsatellite markers screening from EST sequences of Larimichthys crocea

A normalized gonad cDNA library of Larimichthys crocea was constructed, from which 3535 EST were obtained by sequencing clones. The frequency and density of 2 -6 bp SSR were analyzed from these ESTs. Amount of 150 SSR （4.24%） were obtained, among which there were 64 dinucleotide, 80 trinucleotide, 5 tetranucleotide and 1 pentanucleotide sequences. The trinucleotide repeats motifs were the most abundant motif in these SSR （53.3%）. Among the dinucleotide and trinucleotide sequences （TG/GT/AC/CA） n and （GAG/AGG/GGA/CCT） n repeats were the dominant motifs, which accounted for 26% and 14%, respectively. 62 pairs of primers were designed from EST sequences containing SSR. And 8 of them showed polymor- phic PCR products by electrophoresis on 2. 0% agarose gel. Polymorphism rate was 12. 9%. The results will contribute to the development of EST - SSR marker and the research of genes which contain SSR in coding regions.