Němečková Alžběta, Koláčková Veronika, Vrána Jan, Doležel Jaroslav, Hřibová Eva
Institute of Experimental Botany of the Czech Academy of Sciences, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc, Czech Republic.
J Exp Bot. 2020 Oct 22;71(20):6262-6272. doi: 10.1093/jxb/eraa370.
Despite much recent progress, our understanding of the principles of plant genome organization and its dynamics in three-dimensional space of interphase nuclei remains surprisingly limited. Notably, it is not clear how these processes could be affected by the size of a plant's nuclear genome. In this study, DNA replication timing and interphase chromosome positioning were analyzed in seven Poaceae species that differ in their genome size. To provide a comprehensive picture, a suite of advanced, complementary methods was used: labeling of newly replicated DNA by ethynyl-2'-deoxyuridine, isolation of nuclei at particular cell cycle phases by flow cytometric sorting, three-dimensional immunofluorescence in situ hybridization, and confocal microscopy. Our results revealed conserved dynamics of DNA replication in all species, and a similar replication timing order for telomeres and centromeres, as well as for euchromatin and heterochromatin regions, irrespective of genome size. Moreover, stable chromosome positioning was observed while transitioning through different stages of interphase. These findings expand upon earlier studies in suggesting that a more complex interplay exists between genome size, organization of repetitive DNA sequences along chromosomes, and higher order chromatin structure and its maintenance in interphase, albeit controlled by currently unknown factors.
尽管最近取得了很大进展，但我们对植物基因组组织原理及其在间期细胞核三维空间中的动态变化的理解仍然非常有限。值得注意的是，尚不清楚这些过程如何受到植物核基因组大小的影响。在本研究中，分析了七种基因组大小不同的禾本科物种的DNA复制时间和间期染色体定位。为了提供全面的情况，使用了一套先进的互补方法：用乙炔基-2'-脱氧尿苷标记新复制的DNA，通过流式细胞术分选在特定细胞周期阶段分离细胞核，三维免疫荧光原位杂交和共聚焦显微镜。我们的结果揭示了所有物种中DNA复制的保守动态，以及端粒和着丝粒以及常染色质和异染色质区域相似的复制时间顺序，而与基因组大小无关。此外，在间期的不同阶段过渡时观察到稳定的染色体定位。这些发现扩展了早期的研究，表明基因组大小、沿染色体的重复DNA序列组织、高阶染色质结构及其在间期的维持之间存在更复杂的相互作用，尽管受目前未知因素的控制。
