[DNA synthesis in isolated nuclei of Misgurnus fossilis loach embryos. I. Characteristics of the system].

System for studying DNA synthesis in the isolated nuclei of loach Misgurnus fossilis embryo was described. Nuclei from 13--15 h embryo incorporated 2--3 pmoles of [3H]TMP or [3H]dCMP per microgram of DNA during 30 min of incubation in the reaction mixture. The incorporation was inhibited by ethidium bromide, actinomycin D, and N-ethylmaleimide. The incorporation was Mg2+- and ATP-dependent. Adenosine diphosphate at a concentration of 10 mM enhanced the label incorporation into DNA about twofold. Nicotinamide adenine dinucleotide, polyamines, heparin, and histones inhibited label incorporation into nuclear DNA.