CHAPTER 9 



Chromosome Aberrations Induced in Animal Cells 

 by Ionizing Radiations 1 



Berwind P. Kaufmann 



Department of Genetics, Carnegie Institution of Washington, Cold Spring 



Harbor, New York 



Introduction. Nature of the induced rearrangements: Methods of diagnosis — Types of 

 induced chromosomal aberrations. The process of structural rearrangement: The breakage 

 process. Differences in sensitivity to ionizing radiations: Relative sensitivity of different 

 organisms — Effect of ploidy — Relative sensitivity of chromosomes in different types of 

 cells of the same species — Changes in sensitivity of chromosomes in cells of the same type. 

 Chemical and cytochemical studies. References. 



1. INTRODUCTION 



The effects on living cells of higher plants and animals of exposure to 

 ionizing radiations are evidenced by various alterations in the constitu- 

 tion and behavior of cellular materials. Among the most readily detect- 

 able reactions are those that modify the form and pattern of association 

 of chromosomes and the course of their separation in the cycle of mitosis. 

 Cytologic examination of irradiated cells has disclosed a variety of aber- 

 rant types, in which the chromosomes were either adherent or clumped, 

 fragmented or reconstituted, excessive or deficient in number. Many of 

 these abnormalities were observed in the pioneer studies of the biologic 

 effects of radiation carried on during the early years of the century (for 

 example, Bergonie and Tribondeau, 1904, 1906, on rat testes; Krause 

 and Ziegler, 1906, on various mammalian tissues; Perthes, 1904, P. Hert- 

 wig, 1911, Payne, 1913, and Holthusen, 1921, on eggs of Ascaris; Koer- 

 nicke, 1905, and Gager, 1908, on somatic and meiotic cells of plants; 

 Mohr, 1919, on testes of grasshoppers; Amato, 1911, and Grasnick, 1918, 

 on cells of amphibia). However, no consistent interpretation of the 

 nature and sequence of origin of the various types of aberrations was 

 developed. This was partly because most of the observations were made 



1 This manuscript was prepared prior to Apr. 1, 1951. Although a few changes 

 have been made since then, this essentially represents the literature available at that 

 time. 



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