LEE, Yung Nok (Dept. of Biology, Korea University) Effects of Cobalts-60 γ-ray irradiation on the physiological and biochemical activities of Chlirella. Kor. J. Bot., Ⅶ(3):9-14, 1964
The sensitivities of Chlorella ellipsoidea to r-ray from Cobalt-60 were determined by measuring the photosynthetic and respiratory activities and the changes in phosphate contents in various fractions of the irradiated cells, which were further grown in a standard medium after irradiation, were compared to those of non-irradoated normal cells.
The photosynthetic and respiratory activities of the cells were almost inversely propotional to the dose of γ·ray irradiated and the photosynthetic activity was more sensitive than the respiratory activity of the cells. The most sensitive to γ-ray was growth activity, followed by photosynthesis, exogenous and endogenous respirations of the cells in decreasing order.
Chlorella cells were so resistant to γ-ray compared with other organisms that about 280,OO0 r dose of γ-ray irradiation was necessary to reduce as much as half the subsequent photosynthetic activity.
When the irradiated algae were further cultured in a standard medium, the phosphate contents in the fraction of DNA, RNA and phosphoprotein decreased considerably compared with those of non-irradiated normal cells, while the phosphate contents in the fraction of polyphosphates increased than those of control.
Therefore, it was deduced that γ-ray inhibited the synthesis of DNA from polyphosphates, that the synthetic activitied of RNA and protein were decreased owing to either these indirect effect on DNA synthesis or the direct effect of γ-ray itself, and that the growth of Chlorella cells were consequently retarded.
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