【摘要】 通过对中国明对虾基因组随机DNA片断的测序 ,我们获得了总长度约 6 4 10 0 0个碱基的基因组DNA序列 ,从中共找到 172 0个重复序列。其中 ,小卫星序列的数目为 398个 ,占重复序列总数目的 2 3 14 %。这些小卫星序列的重复单位长度为 7- 16 5个碱基 ,集中分布于 7- 2 1个碱基范围内 ,其中以重复单位长度为 12个碱基的重复序列数目最多 ,为 5 8个 ,占小卫星重复序列总数目的 14 5 7%。不同拷贝数目所对应的重复序列的数目情况为 :拷贝数目为 2的重复单位所组成的重复序列数目最多 ,为 137个 ;其次是拷贝数目为 3的重复序列 ,为12 2个 ,且随着拷贝数目的增加 ,由其所组成的重复序列的数目呈递减的趋势。其中一部分序列见GeneBank数据库 ,登录号为AY6 990 72 -AY6 990 76。 398个重复序列分别由 398种重复单位所组成 ,因而小卫星重复序列的类型很多 ,我们初步分成三类 :两种碱基组成类别、三种碱基组成类别和四种碱基组成类别 ,并进一步根据各个重复序列中所含有的碱基种类的数量从大到小排列这些碱基而分成若干小类。从这些分类中可以看出 ,中国明对虾基因组中的小卫星整体上是富含A +T的重复序列 ,并具有一定的“等级制度” ,揭示了其与微卫星重复序列之间的关系 ,即一部分小卫星重复序列可能起源于微卫星更多还原

【Abstract】 Minisatellite sequences are found widely dispersed in the genomes of a variety of higher eukaryotic organisms and some prokaryotic organism.These minisatellite DNA sequences, also referred to as variable-number tandem repeats (VNTR), are comprised of multiple copies of repeats whose base units are in tens of nucleotides (7 to 200 bp) and are found within the genome in variable numbers.Through random sequencing, we totally obtained about 641 000 bp genomic DNA sequences for the Chinese shrimp (Fenneropenaeus chinensis), and identified 1 720 repeat sequences out of them.There are 398 minisatellite sequences, accounting for 23.14% among the 1 720 repeat sequences.The length of repeat units is between 7 and 165 bp, mainly between 7 and 21, in which the copy numbers of 12 bp are 58, and most among all of repeat units.The numbers of repeat sequences according to the different copy number of all kinds of repeat units are as follows:the numbers of repeat sequences composed of 2 copy number are most, 137; the second are the repeat sequences composed of 3 copy numbers, 122.We also find that the number of repeat sequences is degressive, following the increase of the copy numbers of the repeat unit.Some of the sequences are submitted to the Genebank database, and the accession number is AY699072-AY699076.In our research, the 398 minisatellite sequences are composed of 398 kinds of repeat units, so it is very difficult to classify the minisatellite sequences.We think the minisatellite sequences can be classified into three types:dinucleotide minisatellite sequences composed of two kinds of nucleotide, trinucleotide minisatellite sequences composed of three kinds of nucleotide and tetranucleotide minisatellite sequences composed of four kinds of nucleotide.Further, all of above sequences can be divided into many sub-types according to the composition of nucleotide and their number from large to small.Totally, the minisatellite sequences in F.chinensis are A-T rich.We also discussed the genesis and evolution of minisatellite repeat sequences, and think the minisatellite repeats may come from the microsatellite repeats, which will further form some important sequences such as coding sequences.更多还原