80 



ERNEST POLLARD 



L-Arginme- C incorporation 

 hy E coli after Cobalt-60 

 irradiation 



30 







2 15 3 6 9 12 15 



Fig. 1. — Incorporation of L-arginine into tlie whole cell (upjjer) and TCA insoluble 

 fraction as affected by various doses of '""fo y-radiation. There is always a steady in- 

 crease in the TCA insoluble fraction, but the whole cell fraction rises and falls. 



leakage dne to faulty growth. The fall is not observed in the same way 

 for all amino acids. The uptake into the TCA insoluble fraction is re- 

 duced and also delayed in its rapidity of uptake. Steadily increasing 

 the dose steadily increases all the effects. The doses used, it must be 

 noted, are very large. 



In Fig. 2 the amount of uptake at 6 min is plotted against dose using 

 a logarithmic scale for the uptake. It can be seen that the relationship 

 obeyed is in accord with the requirements of equation (1) and so a value 

 for the inactivation volume, V, can be deduced. 



In Fig. 3 is shown the effect of deuteron bomliardment. The control 

 behaviour is slightly modified by the fact that the cells are on a mem- 

 brane and have to be removed before incubation, but the effect of 

 radiation is clearly the same. Again, the doses used are veiy large. 



This same procedure was followed for histidine, leucine, isoleucine, 

 proline and methionine. In addition, the uptake of i^C-uracil and ^^C- 

 glucose was studied. 



