Zhao Dazhong, Yang Xiaohui, Quan Li, Timofejeva Ljudmilla, Rigel Nathan W, Ma Hong, Makaroff Christopher A
Department of Biology and the Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA.
Plant Mol Biol. 2006 Sep;62(1-2):99-110. doi: 10.1007/s11103-006-9006-1. Epub 2006 Aug 2.
Nuclear reorganization and juxtaposition of homologous chromosomes at late leptotene/early zygotene are essential steps before chromosome synapsis at pachytene. We report the results of detailed studies, which demonstrate that nuclear reorganization and homolog juxtapositioning processes are defective in a null mutant, ask1-1. Our results from 4, 6-diamino-2-phenylindole (DAPI)-stained spreads showed that the "synizetic knot", which is typically found in wild type (WT) meiosis during late leptotene and zygotene, was missing in the ask1-1 mutant. Furthermore, ask1-1 meiocytes exhibited only limited homolog juxtaposition at centromere regions at early zygotene. Immunodetection of the cohesin protein SYN1 identified ask1 defects in cohesin distribution from zygotene to anaphase I. Analysis of meiotic chromosomes in ask1-1 and syn1 single mutants, as well as an ask1-1 syn1 double mutant indicate that ASK1 is required for normal SYN1 distribution during meiotic prophase I and suggest that ask1 associated defects may be primarily related to SYN1 mislocalization.
在细线期晚期/偶线期早期，同源染色体的核重组和并列是粗线期染色体联会之前的关键步骤。我们报告了详细研究的结果，这些结果表明在缺失突变体ask1-1中，核重组和同源染色体并列过程存在缺陷。我们对用4,6-二氨基-2-苯基吲哚（DAPI）染色的铺片进行观察，结果显示，在野生型（WT）减数分裂细线期晚期和偶线期常见的“联会结”，在ask1-1突变体中缺失。此外，ask1-1减数分裂细胞在偶线期早期仅在着丝粒区域表现出有限的同源染色体并列。对黏连蛋白SYN1的免疫检测发现，从偶线期到减数第一次分裂后期，ask1在黏连蛋白分布上存在缺陷。对ask1-1和syn1单突变体以及ask1-1 syn1双突变体的减数分裂染色体分析表明，ASK1是减数分裂前期I正常SYN1分布所必需的，这表明ask1相关缺陷可能主要与SYN1定位错误有关。
