[Ribosomal genes of animals from the radiobiology aspect].

The content of ribosomal genes was determined in DNA of guinea pig, man, rat and rabbit, i. e. of mammals differing in radiosensitivity.

[Changes in the pyrimidine blocks of thymic DNA immediately after gamma irradiation of the animal in a sublethal dosage].

Pyrimidine clusters of thymus DNA were determined in normal conditions and 5-10 min after gamma-irradiation of rabbits with a dose of 2 Gy. It was shown that a relative content of isopliths I and II significantly increased and that of isopliths V and VIII decreased in the exposed DNA as compared to normal. When isopliths were divided into the components a relative content of C2T2 fragments significantly increased in the exposed DNA while that of CT3 and T5 decreased.

[Changes in the kinetics of rabbit thymus DNA re-association in various time periods after gamma-irradiation].

A distinction has been detected in the kinetic curves of the control and in vivo irradiated DNA at the site of the reassociation of moderate and unique genome fractions. This distinction increased with increasing Cot. It was shown that the thermostability decreased and the profiles of DNA duplex thermoelution changed in irradiated rabbits as compared with intact ones.

[Correlation between the species radiosensitivity of animals and concentration of AT-rich sequences in DNA].

The authors have revealed a positive and statistically significant correlation between the sum of T-"pure" and T-rich pyrimidine DNA clusters and radiosensitivity of animals of different species. It was demonstrated that the share of a DNA fraction rich in AT-pairs and denaturing within the temperature range from 55 to 75 degrees increases with increasing specific radiosensitivity of animals.

[Correlation between animal radiosensitivity and kinetics of DNA reassociation].

A study was made of DNA of different animal species with various radiosensitivity: guinea pig, man, rat and rabbit. It was shown that the radioresistance of the organism increases with increasing relative content of a rapidly reassociating fraction in DNA. As the kinetic complexity of moderately repetitive sequences increases and the total percentage of meaddle and unique DNA fractions grows, the radioresistance of the organism decreases.