Schubert Veit, Zelkowski Mateusz, Klemme Sonja, Houben Andreas
Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Stadt Seeland, Germany.
Cytogenet Genome Res. 2016;149(3):218-225. doi: 10.1159/000447681. Epub 2016 Jul 26.
Due to the X-shape formation at somatic metaphase, the arrangement of the sister chromatids is obvious in monocentric chromosomes. In contrast, the sister chromatids of holocentric chromosomes cannot be distinguished even at mitotic metaphase. To clarify their organization, we differentially labelled the sister chromatids of holocentric Luzula and monocentric rye chromosomes by incorporating the base analogue EdU during replication. Using super-resolution structured illumination microscopy (SIM) and 3D rendering, we found that holocentric sister chromatids attach to each other at their contact surfaces similar to those of monocentrics in prometaphase. We found that sister chromatid exchanges (SCEs) are distributed homogeneously along the whole holocentric chromosomes of Luzula, and that their occurrence is increased compared to monocentric rye chromosomes. The SCE frequency of supernumerary B chromosomes, present additionally to the essential A chromosome complement of rye, does not differ from that of A chromosomes. Based on these results, models of the sister chromatid arrangement in mono- and holocentric plant chromosomes are presented.
由于体细胞中期呈X形结构，在单着丝粒染色体中姐妹染色单体的排列很明显。相比之下，即使在有丝分裂中期，全着丝粒染色体的姐妹染色单体也无法区分。为了阐明它们的组织结构，我们在复制过程中通过掺入碱基类似物EdU对全着丝粒的 Luzula 染色体和单着丝粒的黑麦染色体的姐妹染色单体进行了差异标记。使用超分辨率结构光照显微镜（SIM）和三维重建，我们发现全着丝粒的姐妹染色单体在早中期时在其接触面上相互附着，类似于单着丝粒染色体。我们发现姐妹染色单体交换（SCE）沿着 Luzula 的全着丝粒染色体均匀分布，并且与单着丝粒的黑麦染色体相比，其发生频率增加。在黑麦基本A染色体组之外额外存在的B染色体的SCE频率与A染色体的SCE频率没有差异。基于这些结果，我们提出了单着丝粒和全着丝粒植物染色体中姐妹染色单体排列的模型。
