Notbohm H
Eur Biophys J. 1986;13(6):367-72. doi: 10.1007/BF00265672.
Neutron and X-ray small angle scattering techniques have been applied to study chromatin structure inside different types of cell nuclei. Scattering from genetically inactive chicken erythrocyte nuclei exhibits a maximum at Q = 0.1-0.15 nm-1 which cannot be observed by studying isolated chromatin derived from the same kind of cells. In highly active transcribing rat liver nuclei such a nuclear pattern is absent. The radius of gyration of isolated "superbeads" was determined. It is discussed whether the characteristic maximum of the nuclei originates from this superstructural organisation of chromatin. Rat liver nuclei were fractionated on sucrose gradients in order to determine whether the absence of the extra maximum in scattering profiles of these nuclei is due to overlapping effects of different chromatin organisation in the various cell types of the liver. As compared to unfractionated nuclei no strong deviations in the scattering profiles of the fractions could be observed. Erythrocyte nuclei were dialysed in buffers differing in the ionic strength of monovalent cations. The typical maximum from the nuclei is shifted from 60 nm (very low salt concentration) to about 35 nm (physiological ionic strength) and is linearly proportional to the decreasing radius of the nuclei. In conclusion, chromatin structure inside the nucleus has a scattering maximum due to an ordered packing of the fibres which is absent in nuclei with high genetic activity.
中子和X射线小角散射技术已被应用于研究不同类型细胞核内的染色质结构。来自基因不活跃的鸡红细胞核的散射在Q = 0.1 - 0.15 nm-1处出现最大值，而通过研究源自同类型细胞的分离染色质则无法观察到这一现象。在高度活跃转录的大鼠肝细胞核中，不存在这样的核模式。测定了分离的“超级珠”的回转半径。讨论了细胞核的特征最大值是否源自染色质的这种超结构组织。对大鼠肝细胞核进行蔗糖梯度分级分离，以确定这些细胞核散射图谱中额外最大值的缺失是否是由于肝脏各种细胞类型中不同染色质组织的重叠效应。与未分级分离的细胞核相比，各分级分离物的散射图谱中未观察到强烈偏差。将红细胞核在单价阳离子离子强度不同的缓冲液中进行透析。细胞核的典型最大值从60 nm（极低盐浓度）移至约35 nm（生理离子强度），并与细胞核半径的减小呈线性比例关系。总之，细胞核内的染色质结构由于纤维的有序堆积而具有散射最大值，而在高遗传活性的细胞核中则不存在这种现象。
