Acta Vet. Brno 2007, 76: 215-222

Influence of Gamma Irradiation on DNA Methylation in Liver of Male Rats and their Offspring

M. Kožurková1, L. Letavayová2, E. Mišúrová2

1P. J. Šafárik University, Faculty of Sciences, Institute of Chemistry, Department of Biochemistry, Košice, Slovakia,
2P. J. Šafárik University, Faculty of Sciences, Institute of Biological and Ecological Sciences, Department of Cellular Biology, Košice, Slovakia

Received November 28, 2006
Accepted April 26, 2007

In the present work, the influence of gamma radiation (3 Gy) on DNA methylation in slowly proliferating liver tissue of adult male rats and their offspring was studied. Total methylation of DNA was determined on the basis of presence of 5-methylcytosine at the inner cytosine of the C-C-G-G sequence by using restriction enzymes, endonuclease Msp I and its isoschisomer Hpa II. It was found that in the liver of control animals, molecular weight distribution of both Msp I and Hpa II digestion products of DNA and the level of DNA methylation were influenced by age mainly between the 3rd and the 7th days of life. At this time, significant difference was found especially in products of cleavage with enzyme Msp I, where an increase in DNA fragments of medium molecular weight (1 - 7 kb) occurred. The changes in the molecular weight distribution of DNA digestion products in the offspring of control rats were accompanied by an increase in the level of total DNA methylation from 29.8% to 67%. In the offspring of irradiated males, the level of DNA methylation was higher in comparison with the offspring of non-irradiated control males, especially on the 3rd day after birth. We suppose that this finding is conjoined with a transgeneration transfer of radiation-induced genome damage.