Lederberg • Genetic Transduction 259 



Joshua Lederberg 

 Genetic Transduction 



Reprinted with the permission of the author 

 and publisher from American Scientist 44(3) : 

 264-280, 1956. 



The recombination of genes stands acid). So far genetic transduction is 



on a par with mutation and selection only known, with certainty, in bacteria 



as a cardinal element of biological but whether this limitation is one of 



variation. In the laboratory, recombi- fact or of technology must still be 



nation furnishes the experimental test found out. 

 of mutational change in genetic units. 



In nature, it leads to their fulfillment historical background 

 by generating a multitude of different 



combinations which are then sifted by Scattered observations that might 



natural selection. Until recently, ge- be attributed to transduction have been 



netic recombination has been closely recorded since the infancy of modem 



identified with sexual reproduction: microbiology' in the last century but 



indeed geneticists consider it to be the could not be understood or coordi- 



principal biological function of sexu- nated in the incomplete genetic theory 



ality, but other processes are now rec- of the time. During the past twenty 



ognized as alternative means to the years, however, an infusion of quan- 



same end. In sexual reproduction, the titative method has nourished bacterial 



fertilization of one intact cell or gamete genetics, and this discipline has en- 



by another precedes the formation of larged that basic concordance of all 



the new zygote and assures the union living forms which comparative bio- 



of a full complement of genes from chemistr\' had firmly substantiated, 



each of two parents. In genetic trans- In higher plants and animals, the 



duction, bv contrast, one cell receives concept of the gene originated from 



only a fragment of the genetic content recombination studies, but in bacteria 



of another. As we shall see, the frag- it arose and for some time depended 



ment can be defined not only in genetic exclusively on mutation studies. This 



but also in physical, chemical, or viro- concept simply states that the heredi- 



logical terms. That is, the fragment tary quality, the intrinsic differences of 



may be associated with subcellular con- organisms, can be analyzed in terms of 



stituents of DNA (desox)'ribonucleic unit factors, markers or genes. Detailed 



