Arai S, Hayashi M, Nakanishi Y H
Department of Veterinary Radiology, Rakuno Gakuen University, Hokkaido, Japan.
J Electron Microsc (Tokyo). 1995 Aug;44(4):191-7.
MgCl2- and KCl-dependent structural changes of chromatin in isolated chicken liver nuclei were examined by scanning electron microscopy. In the absence of salts, the chromatin appeared as granular or knobby fibrillar structures, 15-30 nm in diameter. At 0.2 mM MgCl2, the structures condensed into 30-60 nm fibers. At 2 mM MgCl2, most chromatin was present as condensed chromatin masses. Above 50 mM MgCl2, the condensed chromatin masses were loosened. At KCl concentrations higher than 25 mM, the chromatin appeared as discrete 30-60 nm fibers. However, no condensed chromatin masses were formed at any of the KCl concentrations examined in this study. These results indicate that the MgCl2- or KCl-dependent transitions from a lower to a higher level of chromatin organization in the isolated nuclei are comparable to those reported in isolated chromatin fragments, and that KCl is ineffective in the formation of condensed chromatin.
通过扫描电子显微镜检查了分离的鸡肝细胞核中依赖于MgCl₂和KCl的染色质结构变化。在无盐条件下，染色质呈现为直径15 - 30 nm的颗粒状或瘤状纤维结构。在0.2 mM MgCl₂时，结构凝聚成30 - 60 nm的纤维。在2 mM MgCl₂时，大多数染色质以凝聚的染色质团块形式存在。在高于50 mM MgCl₂时，凝聚的染色质团块会松散。在KCl浓度高于25 mM时，染色质呈现为离散的30 - 60 nm纤维。然而，在本研究检测的任何KCl浓度下均未形成凝聚的染色质团块。这些结果表明，在分离的细胞核中，依赖于MgCl₂或KCl的染色质组织从较低水平向较高水平的转变与在分离的染色质片段中报道的转变相当，并且KCl在凝聚染色质的形成中无效。
