Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Via Ferrata 1, 27100 Pavia, Italy.
Genes (Basel). 2019 Jun 20;10(6):469. doi: 10.3390/genes10060469.
The typical vertebrate centromeres contain long stretches of highly repeated DNA sequences (satellite DNA). We previously demonstrated that the karyotypes of the species belonging to the genus are characterized by the presence of satellite-free and satellite-based centromeres and represent a unique biological model for the study of centromere organization and behavior. Using horse primary fibroblasts cultured in vitro, we compared the segregation fidelity of chromosome 11, whose centromere is satellite-free, with that of chromosome 13, which has similar size and a centromere containing long stretches of satellite DNA. The mitotic stability of the two chromosomes was compared under normal conditions and under mitotic stress induced by the spindle inhibitor, nocodazole. Two independent molecular-cytogenetic approaches were used-the interphase aneuploidy analysis and the cytokinesis-block micronucleus assay. Both assays were coupled to fluorescence in situ hybridization with chromosome specific probes in order to identify chromosome 11 and chromosome 13, respectively. In addition, we tested if the lack of centromeric satellite DNA affected chromatid cohesion under normal and stress conditions. We demonstrated that, in our system, the segregation fidelity of a chromosome is not influenced by the presence of long stretches of tandem repeats at its centromere. To our knowledge, the present study is the first analysis of the mitotic behavior of a natural satellite-free centromere.
典型的脊椎动物着丝粒包含长串高度重复的 DNA 序列（卫星 DNA）。我们之前的研究表明，属于 属的物种的核型特征是存在无卫星和基于卫星的着丝粒，代表了研究着丝粒组织和行为的独特生物学模型。使用体外培养的马原代成纤维细胞，我们比较了着丝粒无卫星的 11 号染色体与具有类似大小且含有长串卫星 DNA 的 13 号染色体的分离保真度。在正常条件和有丝分裂抑制剂诺考达唑诱导的有丝分裂应激下，比较了两条染色体的有丝分裂稳定性。使用两种独立的分子细胞遗传学方法——间期非整倍体分析和胞质分裂阻断微核试验。这两种检测方法都与染色体特异性探针的荧光原位杂交相结合，以分别鉴定 11 号染色体和 13 号染色体。此外，我们还测试了在正常和应激条件下，着丝粒卫星 DNA 的缺失是否会影响染色单体的黏合。我们证明，在我们的系统中，染色体的分离保真度不受其着丝粒处长串串联重复的影响。据我们所知，目前的研究是对天然无卫星着丝粒的有丝分裂行为的首次分析。
