PRODUCTION BY X-RAYS OF PETITE COLONIES IN YEAST AND THEIR RADIOSENSITIVITY

THE effect of X-rays on the viability of cytochrome a3-deficient yeast cells, which form petite colonies, has previously been examined and compared with that of the wild type, which forms normal-sized, large colonies1–5. The reported results differ to a certain extent. Thus Moustacchi3, O'Brien5 and Gonzales and Barron2 observed an increase in radiosensitivity of petite cells, while Raut and Simpson1 and Wood4 found no such difference. This discrepancy may be due to strain differences, to the use of either naturally occurring petite mutants or of colonies produced by chemical means, such as acriflavine or gentian violet, or to the use of cells not genetically related and, therefore, not directly comparable.