BIOLOGICAL-ACTIVITY ASSAYS OF CELL-FREE REASSEMBLED NUCLEI - INJECTING CELL-FREE REASSEMBLED NUCLEI INTO UNFERTILIZED EGGS CAN INDUCE THE EGGS TO CLEAVE AND RECONSTITUTE ASTERS, AND THE INJECTED NUCLEI UNDERGOCELL-CYCLE CHANGES

Nucleus may reassemble spontaneously in cell-free mixture of HeLa meta phase chromosomes, Xenopus egg extracts and ATP-regenerating system, a nd the nucleus shows some biological activities. It is found that, aft er being injected into unfertilized mature eggs, the cell-Free reassem bled nuclei can cause the eggs to cleave and reconstitute asters in th eir cytoplasm, and the injected nuclei undergo changes in response to cell cycle regulators stored in the eggs, and that reinjecting cytosta tic Factors (CSF) into the eggs on stabilize the eggs in mitotic phase , cause the nuclei disassembly and chromatin condensation to chromosom es.