[Effect of free 5-bromodeoxyuridine on induction of SCE in human lymphocytes gamma-irradiated at the presynthetic stage of primary and secondary mitotic cycles].

Formation of SCE was studied in lymphocytes irradiated by 60Co gamma-rays at the G1 stage of the first or second mitotic cycles. The yield of SCEs induced by irradiation in the presence of 5-bromodeoxyuridine (BrdU) proved to be significantly higher than that obtained in the absence of BrdU. The enhancing influence of BrdU on SCE induction depends on neither replication cycle nor the molecular constitution of chromosomes under irradiation.

[Chromosome radiosensitivity in 2 successive mitotic cycles of human lymphocytes].

A culture of human lymphocytes was irradiated with gamma-quanta (0.5 Gy) after incubation during different time intervals, i.e.

[Duration of the mitotic cycle and radiosensitivity of chromosomes in human lymphocytes].

The frequency of chromosome aberrations was studied in human lymphocytes, with different duration of the mitotic cycle (from 48 to 73 h), exposed to gamma-quanta 2 h before fixation (i. e. at the G2 stage).

[Effect of radiation on the formation of isolabels in the late replicating regions of the Chinese hamster genome].

The cells synchronized in the G1 stage were incubated in a medium containing 5-bromodeoxyuridine, and chromosomes were analysed after two rounds of replication Iso-labels (IL) were observed in the late-replicating (heterochromatic) segments. The frequency of IL increased after irradiation during the G2 stage of the second cycle. Moreover, IL were observed in euchromatic segments (not recorded in control cells), whereas the frequency of sister chromatid exchanges decreased.

[Effect of cell respiration inhibitors on the formation of structural mutations in human lymphocytes irradiated at different stages of the mitotic cycle].

Human lymphocytes were irradiated by 60Co gamma-rays after 0, 10, 20, 35, 45, 48 and 49.5 h of incubation. Immediately after irradiation sodium cyanide, sodium fluoride or monoiodoacetic acid was given for 2.