多头绒泡菌核仁骨架的研究

从多头绒泡菌（Ｐｈｙｓａｒｕｍ　ｐｏｌｙｃｅｐｈａｌｕｍ　Ｓｃｈｗ）间期细胞核中分离出核仁，用ＤＮａｓｅ　Ｉ、０．２５ｍｏｌ／Ｌ（ＮＨ４）２ＳＯ４和２ｍｏｌ／ＬＮａＣｌ去除核仁ＤＮＡ和大部分蛋白质，得到核仁骨架。核仁骨架是直径１０３０ｎｍ的纤维组成的网络结构，含有约２０种多肽，其中包括与肌动蛋白电泳迁移率相当的４３ｋＤ左右的多肽。免疫荧光检测结果表明，核仁骨架能与肌动蛋白抗体结合而发出明亮的荧光。免疫斑点印迹结果进一步证实，核仁骨架的蛋白质成分中存在肌动蛋白。免疫电镜结果指出，代表肌动蛋白的金颗粒分布在整个核仁中。

Actin Is Localized in the Nucleolar Skeleton of Physarum polycephalum

Nucleoli were isolated from the interphase nuclei of Physarum polycephalum Schw. The nucleolarskeleton was obtained after DNA and most of the nucleonal proteins were extracted with DNase I, 0. 25 mol/L(NH4)2SO4 and 2 mol /L NaCl. The nucleolar skeleton appeared as a fibrous network structure composed of fibres about 10 to 30 nm in diameter when observed under the electron microscope. SDS-PAGE analyses revealed about 20 polypeptides in the nucleolar skeleton, including a 43 kD polypeptide which is equivalent toactin in molecular weight. Immunofluorescence observations upon slide preparations of the nucleolar skeletonlabeled with anti-actin antibody showed that the nucleolar skeleton emanated bright fluorescence, indicating theexistence of the antigen. Immunodotting assays further localized actin in the protein prepalations of the nucleolar skeleton. Results of immuno--electron microscopy, with anti-actin antibody and protin A-gold as probes,indicated that gold particles were distributed all over the nucleolus of the interphase nucleus.