THE STUDY OF NUCLEI SELF-ASSEMBLY AND CHROMATIN FIBRES IN THE ASSEMBLED NUCLEI IN A CELL-FREE SYSTEM OF XENOPUS EGGS
爪蟾卵无细胞系统中核的自组装和组装核染色质纤维的研究

Using the eggs of Xenopus laevis, we set up an in vitro cell-free system. Under the fluroescent microscope and the electronic microscope, we observed the self-assembly of nuclei when Lambda DNA or chromatin was added to the cell-free system. Right after the adding of Lambda DNA, fibres were observed, then, they changed into irregular blocks, and small spheres, at last, assembled nuclei were formed which had the similar shape and structure to the inter-phase nuclei of eukaryotic cells. A similar but faster process was also observed when chromatin had been added to the system.The assembled nuclei were broken with osmotic shock in order to release their chromatin fibres. The released fibres looked like the chromatin fibres of a cell nucleus in some ways but had their own properties. Treated by protease, the fibres became smoother and the pellets on them disappeared. DNase digestion resulted in the disappearance of fibres, while the pellets and some segments of the fibres still remained. There seemed no effects when the fibres were treated by RNase.