ZINDER AND LEDERBERG 



Horowitz, N. H. 1948 The one gene-one en- 

 zyme hypothesis. Genetics 33:612-613. 



1950 Biochemical genetics of Neurospora. 

 Advances in Getietics 3:33-71. 



Lederberg, J. and Zinder, N. 1948 Concentra- 

 tion of biochemical mutants of bacteria 

 with penicillin. /. Avier. Che?n. Soc. 70: 

 4267. 



221 



Mitchell, H. K. and Lcin, J. 1948 A Neuro- 

 spora mutant deficient in the enzymatic 

 synthesis of tryptophan. /. Biol. Chem. 

 175:481^82. 



Umbarger, H. E. and Mueller, J. H. 1951 

 Isoleucine and valine metabolism of Es- 

 cherichia colt. I. Growth studies on amino 

 acid-deficient mutants. /. Biol. Che?fi. 189: 

 277-285. 



W 



Genetic Exchange in Salmonella 



NORTON D. ZINDER a?ld JOSHUA LEDERBERG 



Reprinted by authors' and publisher's permis- 

 sion from Journal of Bacteriology, vol. 64, 1952, 

 pp. 679-699. 



The strikmg discovery of sex in bacteria (p. 192) ivas followed 

 a few years later by this paper, which demonstrates an eve?i more 

 unusual phenomenon. Evidence is prese?ited to show that hereditary 

 materials from one strain of bacterium can be carried to a second 

 strain by a completely different organism— a virus. The materials so 

 carried are then traiismitted by the second strain in a normal heredi- 

 tary seque?ice, through many ge?ieratioj2s. The relationship between 

 this phenomena?! and the occurreyice of uncontrolled and prese?itly 

 uncontrollable outbursts of genetic activity in higher organisins is 

 of great sig?iificance in medical research, as evidenced by the recog- 

 fiition of Dr. Lederberg's work o?i this and sexual recombination in 

 bacteria by the Nobel Prize Committee in 1958. 



Genetic investigations with many 

 different bacteria have revealed paral- 

 lelisms and some contrasts with the 

 biology of higher forms. The success- 

 ful application of selective enrichment 

 techniques to the study of gene re- 

 combination in Escherichia coli (Ta- 

 tum and Lederberg, 1947; Lederberg 

 et al., 1951) suggested that a similar 

 approach should be applied to other 



bacteria. This paper ^ presents the re- 



1 Department of Genetics, paper no. 479. 

 This investigation was supported by research 

 grants (E72) from the National Microbi- 

 ological Institute of the National Institutes of 

 Health, Public Health Service, from the 

 Rockefeller Foundation and from the Re- 

 search Committee of the Graduate School 

 from funds supplied by the Wisconsin 

 Alumni Research Foundation. This work has 

 been submitted by the senior author to the 



