Molecular organization of terminal repetitive DNA in Beta species
Molecular organization of terminal repetitive DNA in Beta species
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DOI：
10.1007/s10577-006-1096-8
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发表时间：
2006-12-01
影响因子：
2.6
通讯作者：
Schmidt, Thomas
中科院分区：
文献类型：
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作者：
Dechyeva, Daryna;Schmidt, Thomas
我们从Beta属四个组的物种和与藜科有亲缘关系的菠菜中分离出亚端粒卫星DNA序列家族。对25个克隆进行了测序，并用Southern blotting和FISH对每个家族的代表性重复序列进行了特征分析。ApaI限制性卫星重复序列家族分别命名为pAv34、pAc34，RsaI重复序列家族分别命名为pRp34、pRn34和pRs34。重复单位长度为344-362bp，同源性为45.7-98.8%，有明显的种属差异。每个卫星单体分别由165-184个碱基的两个亚重复序列SR1和SR2组成。每个亚重复组的重复序列在物种间高度一致，但与另一个亚重复组成员的同源性仅为40.8-54.8%。在亚端粒卫星家族的系统发育中，可以认为有两个进化步骤：在贝塔和脊椎动物物种的祖先中，祖先卫星多样化为代表SR1和SR2的组，随后在物种辐射过程中，由此产生的360bp重复序列二聚化和多样化为片段特异的卫星DNA家族。用多色FISH技术对端粒、亚端粒和rDNA串联重复序列的染色体定位进行了研究。纤维FISH的高分辨率分析揭示了普通菜豆染色体末端独特的物理结构，端粒DNA和亚端粒卫星分别延伸到最大63kb和125kb。
We have isolated families of subtelomeric satellite DNA sequences from species of four sections of the genus Beta and from spinach, a related Chenopodiaceae. Twenty-five clones were sequenced and representative repeats of each family were characterized by Southern blotting and FISH. The families of ApaI restriction satellite repeats were designated pAv34, pAc34, the families of RsaI repeats pRp34, pRn34 and pRs34. The repeating units are 344-362 bp long and 45.7-98.8% homologous with a clear species-specific divergence. Each satellite monomer consists of two subrepeats SR1 and SR2 of 165-184 bp, respectively. The repeats of each subrepeat group are highly identical across species, but share only a homology of 40.8-54.8% with members of the other subrepeat group. Two evolutionary steps could be supposed in the phylogeny of the subtelomeric satellite family: the diversification of an ancestor satellite into groups representing SR1 and SR2 in the progenitor of Beta and Spinacea species, followed by the dimerization and diversification of the resulting 360 bp repeats into section-specific satellite DNA families during species radiation. The chromosomal localization of telomeric, subtelomeric and rDNA tandem repeats was investigated by multi-colour FISH. High-resolution analysis by fibre FISH revealed a unique physical organization of B. vulgaris chromosome ends with telomeric DNA and subtelomeric satellites extending over a maximum of 63 kb and 125 kb, respectively.