ABSTRACT Dehydration of cells by acute hyperosmotic stress has profound effects upon cell structure and function. Interphase chromatin and mitotic chromosomes collapse (“congelation”). HL-60/S4 cells remain ~100% viable for, at least, 1 hour, exhibiting shrinkage to ~2/3 their original volume, when placed in 300mM sucrose in tissue culture medium. Fixed cells were imaged by immunostaining confocal and STED microscopy. At a “global” structural level (μm), mitotic chromosomes congeal into a residual gel with apparent (phase) separations of Ki67, CTCF, SMC2, RAD21, H1 histones and HMG proteins. At an “intermediate” level (sub-μm), radial distribution analysis of STED images revealed a most probable peak DNA density separation of ~0.16 μm, essentially unchanged by hyperosmotic stress. At a “local” structural level (~1-2 nm), in vivo crosslinking revealed essentially unchanged crosslinked products between H1, HMG and inner histones. Hyperosmotic cellular stress is discussed in terms of concepts of mitotic chromosome structure and liquid-liquid phase separation.

中文翻译：

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高渗压力：原位染色质相分离

摘要 急性高渗应激引起的细胞脱水对细胞结构和功能具有深远的影响。间期染色质和有丝分裂染色体塌陷（“凝结”）。当将 HL-60/S4 细胞置于组织培养基中的 300 mM 蔗糖中时，HL-60/S4 细胞在至少 1 小时内保持 ~100% 的存活率，表现出收缩至其原始体积的 ~2/3。固定细胞通过免疫染色共聚焦和 STED 显微镜成像。在“全局”结构水平 (μm) 上，有丝分裂的染色体凝结成残留的凝胶，Ki67、CTCF、SMC2、RAD21、H1 组蛋白和 HMG 蛋白明显（相）分离。在“中间”水平（亚微米），STED 图像的径向分布分析显示，最有可能的峰值 DNA 密度分离约为 0.16 微米，高渗应力基本保持不变。在“局部”结构水平（~1-2 nm），体内交联显示 H1、HMG 和内部组蛋白之间的交联产物基本上没有变化。根据有丝分裂染色体结构和液-液相分离的概念讨论高渗细胞应激。