In diverse conditions intrinsic chromatin condensate have liquid-like material properties

The organization of eukaryotic chromatin is important in many nuclear processes. Recent studies have shown that chromatin fragments can self-assemble by phase separation into micron-scale structures in the presence of salt in vitro. There are discrepancies regarding whether these structures generally have liquid-like or solid-like behaviors, an important distinction in considering how processes such as transcription and chromosome remodeling by loop extrusion can occur in cells. Here, we resolve conflicting reports by demonstrating that chromatin condensates have liquid-like behaviors in diverse solution conditions and describing aspects of sample handling that can lead to artifactual solid-like behaviors. Our data suggest how chromatin can be dynamic on short length scales but restrained on long length scales, as observed in cells., ,真核染色质的组织在诸多核过程中发挥着关键作用。近期研究表明，在体外（in vitro）加盐的条件下，染色质片段可通过相分离自组装形成微米级结构。关于此类结构通常表现为类液态还是类固态行为，目前尚存争议——这一区分对于理解细胞内转录、环挤出介导的染色体重塑等过程的运作机制至关重要。本研究通过证实染色质凝聚体在多种溶液条件下均呈现类液态行为，并阐明可能导致伪类固态行为的样品处理环节，解决了此前的报告分歧。我们的数据揭示了染色质如何如细胞内观测到的那样，在短长度尺度下保持动态性，而在长长度尺度下受到约束。