ORGANIZATION AND EVOLUTION OF A HIGHER-PLANT ALPHOID-LIKE SATELLITE DNA-SEQUENCE
ORGANIZATION AND EVOLUTION OF A HIGHER-PLANT ALPHOID-LIKE SATELLITE DNA-SEQUENCE
复制标题
DOI：
10.1016/0022-2836(86)90329-3
复制
发表时间：
1986-02-20
影响因子：
5.6
通讯作者：
DELSENY, M
中科院分区：
文献类型：
--
作者：
GRELLET, F;DELCASSO, D;DELSENY, M
从萝卜核DNA中分离到两个重组质粒，分别含有177个碱基对（bp）元件的3个和8个串联重复序列。这些质粒被用作探针来研究基因组内该元件的组织和拷贝数。该序列在. simeq中呈现。0.6百万份拷贝。限制性内切酶分析提供了序列异质性的证据，并揭示了非重叠亚家族的发生。对9个单位进行了测序，发现它们非常保守。然而，两个克隆中的序列显然属于两个不同的亚组。我们的数据表明，这些序列以协调一致的方式进化，并且肯定发生了基因转换等均质化机制。该177 bp序列由源自共同祖先的三个60 bp区块组成。这三个区块之间的交换可能发生在它们被固定为短序列的拼凑物之前，即177 bp的元件。然后分几步扩增该177 bp的单元。当在低严格条件下进行杂交时，可以在其它十字花科中检测到这种重复序列的存在。与先前发表的芥菜卫星DNA序列的直接比较表明类似的组织和75%的同源性。同源性也被发现具有较短的区域（. simeq. 60 bp）的蚕豆和玉米卫星DNA。最后，同源性也被发现与几个动物alphoid序列，这表明这个家庭也发生在植物基因组。
Two recombinant plasmids containing, respectively, three and eight tandem repeats of a 177 base-pair (bp)element from radish nuclear DNA have been isolated. These plasmids were used as probes to investigate the organization and the copy number of this element within the genome. This sequence is presented in .simeq. 0.6 million copies. Restriction analysis provides evidence for sequence heterogeneity and reveals the occurrence of non-overlapping subfamilies. Nine units were sequenced and found to be remarkably conserved. However, sequences in the two clones clearly belong to two distinct subgroups. Our data suggest that these sequences evolved in a concerted manner and that homogenization mechanisms such as gene conversions certainly took place. The 177 bp sequence is made from three 60 bp blocks that are derived from a common ancestor. Exchanges between the three blocks probably occurred before they became fixed as a patchwork of short sequences, the 177 bp element. This unit of 177 bp was then amplified in several steps. The presence of such a repeated sequence can be detected in other Cruciferae when hybridizations are carried out under low stringency conditions. Direct comparison with a previously published mustard satellite DNA sequence indicates a similar organization and a 75% homology. Homology was also found with shorter regions (.simeq. 60 bp) of broad bean and corn satellite DNA. Finally, homology was also found with several animal alphoid sequences, suggesting that this family also occurs in the plant genomes.