/6- 



Physical and Chemical Factors 



Modifying the Sensitivity of Cells 



to High-Energy and Ultraviolet Radiation * 



ALEXANDER HOLLAENDER 



Biology Division 



Oak Ridge National Laboratory 



Oak Ridge, Tennessee 



Microorganisms are in some ways ideal materials for obtaining imme- 

 diate quantitative information on some of the basic aspects of radiation 

 effects. It is well known that they can often be handled in very large 



100 



Aspergillus terrcus 

 Normal spores 

 Irradiated dry 



■ Proton or alphas 

 • X-rays 







20 



40 



120 



60 

 Dose, kilorep 



Fig. 1. Comparative lethal action of x-rays (250 kev), of protons, and of alpha 

 particles on dry spores of Aspergillus terreus. [From Stapleton and Martin (18).] 



numbers, thus giving statistical results on effects which are hardly rec- 

 ognizable on higher organisms. They are, in general, not suitable for 



* This work was done under Contract No. W-7405-Eng-26 for the Atomic Energy 

 Commission. 



285 



