The effect of chronic exposure to low doses of radiation on the isoenzyme profile of diaphorase in individuals of natural populations of Helix pomatia (L.) and Calliptamus italicus (L.), inhabiting a territory with increased levels of radiation caused by continuous contamination with technogenic radionuclides has been studied. In individuals of the same species from regions with normal natural radioactive background there have been registered three isoforms of the gene-enzyme system DIA1, DIA2 and DIA3 distinguished by their electrophoretic mobility. This isoenzyme profile was retained in the various tissues and organs of the organism and was not dependent on the sex or the age of the individuals, which shows the high degree of conservatism of the enzyme system. Lack of DIA3 in the isoenzyme spectrum of diaphorase has been registered in representatives of the populations of H. pomatia (L.) and C. italicus (L.) exposed to chronic effective doses of radiation within the range of 0,84 – 3,36 mSv. In a single whole body exposure to radiation in the laboratory and receipt of equivalent dose of -rays of the order of 3,5 mSv there was a total loss of the activity of DIA3 which, however, did not change the activity of the other two fractions of the system. When the absorbed dose was increased to 6,23 mSv after irradiation with fast neutrons, the activity of all fractions of DIA2 was eliminated which, however, did not influence the activity of DIA1. These changes in the ratio between the isoforms were dependent on the dose of radiation. The change in the isoenzyme spectrum of diaphorase at the time of exposure to low doses of radiation has most probably an adaptive character associated with the provision of energy to the body in terms of acidosis and increasing its resistance to the chronic effects of radiation.
Keywords: Chronic radiation, Diaphorase, Radio-resistance, -rays
