Suppression of nucleic acid synthesis in chromatin of Spirogyra during conjugation process

Marked changes in RNA- and DNA-synthesizing activities of thechromatin fraction were found to be connected with the conjugationprocess of Spirogyra sp. RNA-synthesizing activity of the chromatin fraction was muchlower in conjugating and zygote cells than in vegetatively growingcells. No significant differences were observed in the templateactivities of purified DNA prepared from vegetatively growing,conjugating, and zygote cells. The activities of DNA purifiedfrom vegetatively growing and zygote cells and calf thymus werestrongly inhibited at different levels by binding with histonesprepared from vegetatively growing and zygote cells. DNA-synthesizingactivity of the chromatin fraction of conjugating or zygotecells was much lower than that of vegetatively growing cells. (Received December 24, 1971; )