蜜蜂EST中的微卫星分析

为加速分子标记在蜜蜂遗传、进化与行为等方面的利用，分析了简单重复序列(Simple Sequence Repeats，SSRs)在蜜蜂EST中的分布频率与密度。所分析的蜜蜂EST数据集包含15869条序列，总长为7．9Mb。结果显示，蜜蜂ESTs中SSRs的频率为1／0．52kb，其中6碱基重复基序占总SSRs的45．0％，是最丰富的重复单元，而2、1、3、4与5碱基重复基序分别占总SSRs的17．9％、14．1％、11．6％、9．2％和2．2％。同时，在各种SSRs重复单元中，富含A碱基的重复单元占据优势地位，如：A、AT、AG、AC、AAT、AAG、AAC、AAAT、AAAG、AAAAG、AAAAT、AATAT、AAAAAG和AAAAAT重复基序，而富含G碱基的重复单元在基因编码区中含量较低。进一步分析显示：蜜蜂SSRs在冗余与非冗余EST数据集中的分布频率与密度相似，仅存在极小的偏差，表明可从现有的部分ESTs数据中方便地获取有效的微卫星标记。

Analysis of Microsatellites Derived from Bee ESTs

To accelerate the molecular analysis of genetics,evolution and behavior,etc.in the honey bee (Apis),the frequency and density of simple sequence repeats (SSRs) have been analyzed from the bee EST (expressed sequence tag) database comprising 15 869 sequences amounting to 7.9 Mb.Results showed that the frequency of SSRs was 1/0.52 kb in bee ESTs,and hexanucleotide repeats (45.0%) motifs appeared to be the most abundant type in bee,the dinucleotide,mononucleotide,trinucleotide,tetranucleotide and pentanucleotide repeats are 17.9%,14.1%,11.6%,9.2% and 2.2%,respectively.Meanwhile,the A-rich repeats are predominant in each type of SSRs,such as A,AT,AG,AC,AAT,AAG,AAC,AAAT,AAAG,AAAAG,AAAAT,AATAT,AAAAAG and AAAAAT repeats,whereas G-rich repeats are rare in the coding regions.The further analysis suggests that,apart from minor deviations,there is no significant difference in the distribution and density of microsatellites in the redundant and non-redundant set of bee ESTs.Furthermore,the availability of microsatellite markers can be expected to enhance the power and resolution of genome analysis in bee.