Our understanding of the physical principles organizing the genome in the nucleus is limited by the lack of tools to directly exert and measure forces on interphase chromosomes in vivo and probe their material nature. Here, we introduce an approach to actively manipulate a genomic locus using controlled magnetic forces inside the nucleus of a living human cell. We observed viscoelastic displacements over micrometers within minutes in response to near-piconewton forces, which are consistent with a Rouse polymer model. Our results highlight the fluidity of chromatin, with a moderate contribution of the surrounding material, revealing minor roles for cross-links and topological effects and challenging the view that interphase chromatin is a gel-like material. Our technology opens avenues for future research in areas from chromosome mechanics to genome functions.

中文翻译：

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基因组位点的活细胞显微操作揭示了间期染色质力学

我们对在细胞核中组织基因组的物理原理的理解受限于缺乏工具来直接施加和测量体内间期染色体上的力并探测它们的物质性质。在这里，我们介绍了一种使用活的人类细胞核内的受控磁力来主动操纵基因组位点的方法。我们在数分钟内观察到响应于近皮牛顿力的粘弹性位移，这与 Rouse 聚合物模型一致。我们的结果突出了染色质的流动性，周围材料的贡献适中，揭示了交联和拓扑效应的次要作用，并挑战了相间染色质是凝胶状材料的观点。