Application of capillary electrophoresis to the analysis of soluble chromatin.

Capillary electrophoresis (CE) has been applied to study DNA-protein complexes using as the test system soluble chromatin from chicken erythrocytes and rapidly proliferated cultured Chinese hamster fibroblast-like cells B11-dii-FAF-28. Separation was performed with home-made CE apparatus, using a regulated high-voltage power supply, UV-detector and fused silica capillaries with inner diameter 75 microm. The heterogeneity of nucleosomal particles with different DNA lengths after micrococcal nuclease digestion was detected.

A comparative study of the effects of lucanthone (miracil D) and actinomycin D on the Chinese hamster cells grown in cultures.

Chinese hamster cells of an established clone line grown in monolayers were incubated for up to two hours with either lucanthone (0.3-30 mug/ml) or actinomycin D (0.06-0.10 MUG/ML) AND SUbjected to radioautographic investigations with 3H-uridine during the period of treatment. At concentration of 9 mug/ml lucanthone selectively inhibited the synthesis of nucleolar (ribosomal) RNA while the extranucleolar RNA synthesis proceeded at a high level. Similar results were obtained with 0.08 mug/ml actinomycin D. Protein synthesis and mitotic activity were also affected by lucanthone but the drug did not markedly interfere with DNA synthesis. Lucanthone appeared to be much less effective in cell killing than actinomycin D and its inhibitory effects on the nucleolar RNA synthesis and other cellular processes proved readily reversible. The results allow to conclude that lucanthone may be useful as a tool for studying RNA synthesis in animal cells.

[Inhibition by actinomycin D of ribosomal RNA synthesis in the presynthesis period of the mitotic cycle of Chinese hamster cell cultures]. / Podavlenie aktinomitsinom D sinteza ribosomnoi RNK v presinteticheskom periode mitoticheskogo tsikla kul'tury kletok kitaiskogo khomiachka

Using radioautographic technique actinomycin D at a concentration of 0.08 mug/ml was shown to inhibit selectively ribosomal RNA (rRNA) synthesis in monolayer cultures of Chinese hamster cells. The treatment with actinomycin D of cells synchronized by mitotic selection in the beginning of the G1 period causes a delay in the onset of DNA synthesis. However, a similar treatment in the late G1 period does not prevent cells from entering the S-period. The same effect has been produced by 9 mug/ml lucanthone, another inhibitor of rRNA synthesis. The experiments demonstrate a pronounced difference in cell reaction to the depression of rRNA synthesis in early and late G1 period. The data imply that the formation of rRNA, essential for the initiation of DNA synthesis, is accomplished in the first half of the G1 period, while part of rRNA has been already formed in the previous cycle.