非细胞体系核重构过程的超微结构研究

用电镜观察Lambda DNA与非洲爪蟾卵提取物在非细胞体系内的核重构,发现Lambda DNA首先诱导形成类染色质结构,膜泡、核孔复合体围绕这一结构组装成双层核膜,同时类染色质也随着核膜的装配,表现出从致密凝聚到呈现松散均匀分布的变化。有工作表明,在由染色质诱导的核重构过程中,或者是膜泡先与染色质结合,然后有核孔出现,或者是核孔物质先与染色质作用,膜泡通过结合核孔物质形成双层核膜。我们观察由外源DNA诱导的核重构过程,则发现膜泡与核孔复合体先分别独立地与类染色质结构相互作用,然后核孔复合体再镶嵌到双层核膜中。

ULTRASTRUCTURAL STUDY ON THE PROCESS OF NUCLEAR RECONSTITUTION IN A CELL-FREE SYSTEM FROM XENOPUS EGGS

Nuclear reconstitution around Lambda DNA in a cell-free system from Xenopus eggs involves distinct steps at ultrastructural level. First, Lambda DNA polymers were induced to form chromatin-like structures with the proteins in egg extracts. Then, along with membrane vesicles and nuclear pore components attached to them to assemble double nuclear membranes, these chromatin-like structures underwent variations from condensation to decondensation, simultaneously. It is different from the nuclear reconstitution induced by chromatin in that, while membrane vesicles were attaching to the chromatin-like structures to fuse each other, the assembly of nuclear pore complexes occurred practically.