CHAPTER 12 



Genetic Effects of Radiation in Mammals 1 



W. L. Russell 



Biology Division, Oak Ridge National Laboratory 



Introduction: Effect of radiation on reproduction. Dominant lethals, semilethals, and 

 subvitals: Offspring of presterile-period matings of irradiated males — Offspring of irra- 

 diated females — Offspring of poststerile-period matings of irradiated males — Sex ratio. 

 Dominant sterility. Dominant partial sterility. Dominant visibles. Recessive lethals, 

 semilethals, and viables. Human hazards. References. 



INTRODUCTION 



Most of the information on the genetic effects of radiation in mammals 

 has come from work on the mouse. The small amount of data obtained 

 from rats, rabbits, and guinea pigs is, in general, confirmatory of the 

 results on mice. The only form of ionizing radiation that has been used 

 extensively is X radiation. There is a little information from limited 

 investigations with neutrons and 7 rays. 



Short general review articles have been presented by Snell (1941b) and 

 Russell (1952). The paper by Lea (1947) includes a review of the work 

 on dominant lethals and hereditary partial sterility. Methods for the 

 detection of mutations in mammals have been discussed by Hertwig 

 (1932), Snell (1935, 1945), Catcheside (1947), Falconer (1949), and 

 Russell (1951, 1952). 



Mutations are commonly divided into two categories, chromosomal and 

 point mutations, according to whether or not a structural change in the 

 chromosomes can be detected. Whether radiation-induced point muta- 

 tions include gene mutations, or represent only certain types of chromo- 

 somal change, is still debated. Regardless of its exact nature, the dis- 

 tinction between chromosomal and point mutations has proved to be 

 descriptively useful in Drosophila. In this organism, where observation 

 of the fine details of chromosome structure is possible, and where the 

 chromosomes are so thoroughly marked genetically, even minute struc- 

 tural changes in chromosomes can be detected, and the level below which 

 they would no longer be apparent is sharply definable. In mammals, the 



1 Work at Oak Ridge and preparation of manuscript under Contract No. W-7405- 

 eng-26 for the Atomic Energy Commission. 



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