Laboratory of Non-coding DNA, Institute of Cytology RAS, St. Petersburg, Russian Federation,
Laboratory of Non-coding DNA, Institute of Cytology RAS, St. Petersburg, Russian Federation.
Cytogenet Genome Res. 2021;161(1-2):93-102. doi: 10.1159/000513228. Epub 2021 Feb 18.
Constitutive heterochromatin is the most mysterious part of the eukaryotic genome. It forms vital chromosome regions such as the centromeric and the pericentromeric ones. The main component of heterochromatic regions are tandem repeats (TR), and their specific organization complicates assembly, annotation, and mapping of these regions. Unannotated and unmapped TR arrays are still present in database contigs. In this study, we used a set of TR in the genomes of the pig (Sus scrofa) and the Chinese hamster (Cricetulus griseus) identified with the help of bioinformatics techniques and determined the specificity of the designed probes. The signal of the 4 pig TR probes in spermatogenic cells was often ring-shaped, especially in primary spermatocytes. The rings were located in the regions relatively weakly stained with DAPI. The unique assembly of the centromeric region was traced using the hamster meiotic chromosomes. The probe specific to chromosome 5 was used. Two signals, arranged as rings, were seen at the pachytene stage, similar to those in the pig spermatogenic cells. In the spermatogenic cells of both pig and hamster, the rings appeared on the chromosomes with pericentromeric TR probes. Our observations support the loop model of the centromeric region, the size of the loops being about 50 kb.
组成型异染色质是真核基因组中最神秘的部分。它形成了重要的染色体区域，如着丝粒和着丝粒周围区域。异染色质区域的主要成分是串联重复（TR），它们的特定组织使得这些区域的组装、注释和映射变得复杂。未注释和未映射的 TR 数组仍然存在于数据库 contigs 中。在这项研究中，我们使用了一组在猪（Sus scrofa）和中国仓鼠（Cricetulus griseus）基因组中识别出的 TR，借助生物信息学技术确定了设计探针的特异性。4 个猪 TR 探针在精原细胞中的信号通常呈环形，特别是在初级精母细胞中。这些环位于用 DAPI 染色较弱的区域。使用专门针对 5 号染色体的探针追踪了着丝粒区的独特组装。在减数分裂中期可以看到两个排列成环的信号，类似于猪精原细胞中的信号。在猪和仓鼠的精原细胞中，带有着丝粒周围 TR 探针的染色体上出现了环。我们的观察结果支持着丝粒区域的环模型，环的大小约为 50kb。
