日本囊对虾基因组小卫星的特征分析

Analysis of minisatellites in the genome of Marsupenaeus japonicus

为了分析日本囊对虾基因组中小微星序列的分布特征并开发小卫星标记,构建了日本囊对虾随机基因组文库,对其中片段长度为400-1 000bp的3 395个克隆测序,共获得总长度为1 606 711bp的DNA序列。在序列拼接后的2 815个克隆中,筛选到487个小卫星序列,其序列总长度占测序序列总长度的3.97%。小卫星序列中,以12bp重复单位的序列数量最多(8.62%),总体趋势表现为重复单位越长,相应的重复序列数目越少(R=-0.826,P<0.01)。小卫星重复单位拷贝数分布范围以8bp重复单位最广(3.1-47.6),其次是10bp(2.5-44),再次是12bp(2.2-28)。平均拷贝数最高的三种重复类型分别为8bp重复单位(13.45),32bp(9.32)和7bp(9.28)。小卫星序列重复单位的拷贝数分布范围2-48,集中分布在2-30,且表现为拷贝数目越大,其相应的重复序列数目越低的趋势。小卫星序列中,AT含量大于50%的序列占66%小卫星AT含量与相应的序列数目不相关(R=0.063,P<0.05)。小卫星侧翼序列分析表明,随着小卫星GC含量的升高,其两端侧翼序列GC含量表现为不断增大的趋势(R=0.731,P<0.01),小卫星序列的产生与其两端侧翼序列的碱基组成可能存在一定的关系。

In this paper, random genome library of Kuruma prawn Marsupenaeus japonicus was constructed and the lengths of 3 395 sequenced clones were from 400 bp to 1 000 bp. After the 2 815 sequences being spliced, 487 minisatellites were screened in the 1 606 711 bp Kuruma prawn genome sequences. Their cumulative length occupied 3.79% of the total length of DNA sequences. In the minisatellite sequences, twelve-nucleotide repeats were the most frequent type, accounting for 8. 62% of the total number of minisatellites. It showed that the number of sequences decreased with the increase of the length of its repeat unit （R = -0. 826, P 〈 0.01 ）. Eight-nucleotide repeat had the largest range of copy number of repeat unit （ 3.1 - 47.6 ）, the following were ten-nucleotide repeat type （ 2.5 - 44） and twelve-nucleotide （ 2.2 - 28 ）, respectively. Descending three repeat types in mean copy number of repeat unit were eight-nucleotide repeat （ 13.45 ）, thirty-two-nucleotide （ 9.32 ） and seven-nucleotide repeat （ 9.28 ）, respectively. The range of copy number of repeat unit varied from 2 to 48, and the copy number mostly ranged from 2 to 30. Moreover, it was showed that the number of corresponding minisatellites decreased as copy number of repeat unit increased. Minisatellite was AT-rich sequence because the number of minisatellites whose AT content was more than 50% occupied 66% of the number of all minisatellites. The correlation between AT content and the corresponding sequence number was little and not significant （ R = 0. 063, P 〉 0. 05 ） in minisatellites. At the same time, GC content of minisatellite increased with the increase of GC content in the corresponding flanking sequences, which might imply that base composition of the flanking sequence has an influence on the origin and evolution of minisatellites.