extracts of the cytoplasm of disrupted spheroplasts of saccharomyces cerevisiae ( bakers ' yeast ) stimulated dna synthesis in a cell-free system consisting of nuclei from spleen cells of the frog xenopus laevis , the stimulation required mg++8 atp , and the deoxynucleoside triphosphates , was saturated by an excess of nuclei or extract , and had kinetics resembling those obtained previously with extracts from mammalian and avian cells .
C0007610
nuclei
C0007634
cells