Alterations in adenylate ratios in plant cells after accelerated ion irradiation.

Levels of adenylate metabolism have been studied in cells of Nicotiana tabacum growing in vitro, and in root apex extracts of Pisum sativum irradiated at the 95-in. isochronous cyclotron U-240, Institute for Nuclear Research, Ukrainian National Academy of Sciences, Kyiv. Particle beams of accelerated helium ions with energy 9.34 keV/micrometer were used. Replacement and rapid freezing of the irradiated plants samples in liquid nitrogen were carried out with a manipulator and a remote control system. After doses of 5, 20, 50, and 100 Gy of gamma-irradiation, as well as 50 and 100 Gy 4He irradiation, the cellular ATP/ADP ratio increased during early stages of the response. This effect was absent at higher doses and after exposure to sparesly-ionizing radiation, when a rapid decline in the cellular ATP concentration and the ATP/ADP ratio occurred.