Cells adapt to drastic changes in genome quantity during evolution and cell division by adjusting the nuclear size to exert genomic functions. However, the mechanism by which DNA content within the nucleus contributes to controlling the nuclear size, remains unclear. Here, we experimentally evaluated the effects of DNA content by utilizing cell-free Xenopus egg extracts and imaging of in vivo embryos. Upon manipulation of DNA content while maintaining cytoplasmic effects constant, both plateau size and expansion speed of the nucleus correlated highly with DNA content. We also found that nuclear expansion dynamics was altered when chromatin interaction with the nuclear envelope or chromatin condensation was manipulated while maintaining DNA content constant. Furthermore, excess membrane accumulated on the nuclear surface when the DNA content was low. These results clearly demonstrate that nuclear expansion is determined not only by cytoplasmic membrane supply but also the physical properties of chromatin, including DNA quantity and chromatin structure within the nucleus, rather than the coding sequences themselves. In controlling the dynamics of nuclear expansion, we propose that chromatin interaction with the nuclear envelope plays a role in transmitting chromatin repulsion forces to the nuclear membrane.

细胞通过调整核大小来发挥基因组功能，以适应进化和细胞分裂过程中基因组数量的剧烈变化。然而，细胞核内 DNA 含量控制细胞核大小的机制仍不清楚。在这里，我们通过利用无细胞非洲爪蟾卵提取物和体内胚胎成像来实验评估 DNA 含量的影响。在维持细胞质效应恒定的同时控制 DNA 含量后，细胞核的平台大小和扩张速度与 DNA 含量高度相关。我们还发现，当控制染色质与核膜的相互作用或染色质浓缩同时保持 DNA 含量恒定时，核膨胀动力学会发生改变。此外，当 DNA 含量较低时，多余的膜会积聚在核表面。这些结果清楚地表明，核扩张不仅取决于细胞质膜的供应，还取决于染色质的物理特性，包括核内的 DNA 数量和染色质结构，而不是编码序列本身。在控制核膨胀的动力学过程中，我们提出染色质与核膜的相互作用在将染色质排斥力传递到核膜方面发挥着作用。