-4- 



RECOMBINATION ANALYSIS 

 IN MICROBIAL SYSTEMS* 



Harriett Ephrussi-Taylor 



NATIONAL CENTER FOR SCIENTIFIC RESEARCH ( FRANCE ) 



Structural and functional properties of living organisms are so diverse 

 that unifying principles are difficult to' discern at the biological level. 

 One of the main aims of experimental biology in our century has 

 therefore been the description of biological processes in terms of the 

 laws of physics and chemistry, in a search for universal principles ap- 

 plying to all kinds of living forms. The border-line science of biochem- 

 istry has provided a certain unification of biology, demonstrating 

 fundamental similarities in the chemical structure of living matter on 

 the one hand and general principles in the way in which chemical en- 

 ergy is made available to cells on the other. The science of genetics has 

 long been recognized as the most general of the truly biological sci- 

 ences. Phenomena of heredity are the same when described by Mendel 

 in a plant or by Morgan in an animal. It is thus not surprising that we 

 are witnessing today the development of a new unifying biological 

 principle in the branch of genetics referred to as molecular genetics. 

 While classical genetics knew no boundary between the plant and ani- 

 mal kingdoms, molecular genetics scarcely admits a separation between 

 the science of polymer chemistry and all of genetics, be it plant or ani- 

 mal, viral or human. 



The molecular theory of genetics states that any given heritable 

 structure is a specific cellular product whose properties are determined 

 with great precision by a particular sequence of bases in the deoxyribo- 



" This work icua aided by a grant from the Rockefeller Foundation to the 

 Lahoratoire de Genetique Phtjsiolugique du C.N.R.S. 



I am indebted to Mr. G. Prevost, Dr. F. Sherman, and Professor B. Ephrussi 

 for vahtablc diseussions and suggestions in the course of preparation of this report, 

 and to Professor Ephrussi for criticism of the manuscript. 



39 



