中国明对虾基因组小卫星重复序列分析

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     

Minisatellite MS32 Alleles Show Population Specificity Among Thai,Chinese, and Japanese

Lineages of structurally related alleles at minisatellite MS32 in human populations show considerable differentiation at the continental level. However, the regional specificity of these lineages remains unknown. We now describe the comparison of allele structures in Thai, Han Chinese, and Japanese populations with lineages previously established for North Europeans and Africans. The great majority of alignable Asian alleles showed their closest structural relative in Asia, with few instances of preferential alignment of Asian with European alleles and only one isolated incident showing a best match with an African allele. Further, there was a strong tendency, most marked for Japanese, for Asian alleles to align preferentially with other alleles from the same population, indicating strong regional specificity of allele lineages. This rapidly evolving minisatellite can therefore serve as a lineage marker for exploring recent events in human population history and dissecting population structure at the fine-scale level, as well as being an extremely informative DNA marker for personal identification.     

Repetitive, genome-specific probes in wheat (Triticum aestivum L. em Thell) amplified with minisatellite core sequences

The detection and analysis of DNA polymorphisms in crops is an essential component of marker-assisted selection and cultivar identification in plant breeding. We have explored the direct amplification of minisatellite DNA by PCR (DAMD-PCR) as a means for generating DNA probes that are useful for detecting DNA polymorphisms and DNA fingerprinting in wheat. This technique was facilitated by high-stringency PCR with known plant and animal minisatellite core sequences as primers on wheat genomic DNA. The products of DAMD-PCR from Triticum aestivum, T. durum, T. monococcum, T. speltoides and T. tauschii showed a high degree of polymorphism and the various genomes could be identified. Cloning of the DAMD-PCR products and subsequent Southern hybridization frequently revealed polymorphic probes showing a good degree of genome specificity. In addition, polymorphic, single locus, and moderately dispersed PCR products were cloned that may have a potential for DNA fingerprinting. Our experiments were limited primarily to diploid wheats and the results indicated that DAMD-PCR may isolate genome-specific probes from wild diploid wheat species that could be used to monitor genome introgression into hexaploid wheat.This paper reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation for its use by the USDA or the University of Missouri. Contribution from the University of Missouri, the Agricultural Experimental Station and U.S. Department of Agriculture-Agricultural Research Service, Plant Genetics Research Unit, journal series No. 12523