Biopolymers and cell. 1996; 12 (4): 65 - 72

Influence of ionizing radiation on structural organization of liver chromatin in rats of different age

T. G. Mozzhukhina, A. Ya. Litoshenko

Wistaradult(6—8ma)andold(26—28mo)ratswereirradiatedwithX-raysatadoseof2Gy.Thekinetics of release of chromatin fragments (CF) extracted by low-salt buffer from liver nuclei at Ccf+, Mg2+-en-donuclease activation, and the features of repressed (RC), transcriptionally active (AC) and matrix-bound (MC) chromatin fractions were evaluated in 1 h and 4 days after irradiation. At «zero time» of endonuclease activation, the content of extracted CF increased in nuclei of intact old rats as compared with adult ones. There was an increase of this parameter in the liver nuclei of adult and old rats in 4 days and 1 h after irradiation accordingly. The release rate ofCF cleavaged by activated endonuclease increased in the nuclei of old intact rats in comparison with adult animals, and changes of this rate were observed after the irradiation only in old rat nuclei. The relative amount ofRC was greater both in nuclei of intact old animals and in nuclei of irradiated rats. These data testify to the resemblance of age-associated and X-ray-induced reorganization ofchromatin structure and indicate the increased susceptibility of liver chromatin of old rats to ionizing irradiation.