Murata M, Ogura Y, Motoyoshi F
Research Institute for Bioresources, Okayama University, Kurashiki, Japan.
Jpn J Genet. 1994 Aug;69(4):361-70. doi: 10.1266/jjg.69.361.
Two highly repetitive DNA sequences have been cloned from Arabidopsis thaliana, ecotype Columbia, and were characterized by molecular and cytological analyses. These two sequences belong to the same repeat family with 180-bp basic unit, being tandemly organized in clusters. Pulsed field gel electrophoresis showed that this repeat sequence family forms at least seven clusters from ca. 100 to 1200 kb in length and ca. 3500 kb in total. Fluorescent in situ hybridization to somatic metaphase cells with the monomeric repeat unit as a probe clearly revealed that this repeat family is located at the centromeric regions of all chromosomes. It was also shown that this repetitive sequence is closely associated with limited parts of heterochromatic blocks on the centromeric regions which are visible distinctly at meiotic prophase from leptotene to diakinesis. Furthermore, this sequence hybridized preferentially to both polar sides of five bivalent chromosomes at the first metaphase. These results suggest that the repetitive sequences of this family were derived from the regions very close to the centromeres or on the centromeres themselves.
从哥伦比亚生态型拟南芥中克隆出了两个高度重复的DNA序列，并通过分子和细胞学分析对其进行了表征。这两个序列属于同一个重复家族，其基本单元为180 bp，呈串联簇状排列。脉冲场凝胶电泳显示，这个重复序列家族形成了至少七个簇，长度约为100至1200 kb，总计约3500 kb。以单体重复单元为探针，对体细胞中期细胞进行荧光原位杂交，清楚地表明这个重复家族位于所有染色体的着丝粒区域。还表明，这个重复序列与着丝粒区域异染色质块的有限部分紧密相关，在减数分裂前期从细线期到终变期都能明显看到这些区域。此外，在第一次中期，这个序列优先与五条二价染色体的两极杂交。这些结果表明，这个家族的重复序列来源于非常靠近着丝粒的区域或着丝粒本身。
