Effect of Radioisotope Disintegration on Cell Culture Cell Viability. ∗

Abstract

Stent and Fuerst(1) have reviewed the applications of the decay of biologically incorporated radioisotopes to genetic and physiological studies in phages and bacteria, By controlled incorporation of a radioisotope into a particular biochemical compound and by using suitable experimental manipulations one may obtain transmutation of one element into another in situ and determine the biological consequences of transmutation under varying physiological conditions. If applicable to mammalian cells in culture, studies similar to those reviewed by Stent and Fuerst(1) could be made with animal cells.

The functioning of the blueprint, DNA, for phage synthesis has been examined in detail by Stent and his co-workers (2,3) using ³²P decay. They found that the information was transferred to a structure not inactivated by ³²P decay after 9 minutes under growing conditions and that protein synthesis was required for this transfer.

These studies have rarely been extended to higher organisms except for the observations that growth in a solution containing a high level of ³²P was abnormal and that the ³²P disintegrations were mutagenic in Droso-philia and Habrobracon (4,5,6).

A priori mammalian cells would presumably be more sensitive to decay of ³²P than microbial cells since the β particle emitted has a longer track inside the mammalian cells, thus superimposing ionizing effects onto that of nuclear recoil and transmutation. The wider function of phosphorus-containing compounds in mammalian cells might be expected either to increase or decrease their sensitivity to this radiation depending upon the essentiality and number of replicas of the incorporating material.

Carrier free ³²P as phosphate was obtained from the Oak Ridge National Laboratory and was sterilized by autoclaving. Phosphate-free medium 199 was obtained from Microbiological Associates, Bethesda, Md., and for the purposes of this experiment it was supplemented with 1 mμmole per ml of PO₄.