BIOLOGICAL TRANSPORT 



in a simple Mendelian manner. The potentialities inherent in such 

 genetically determined transport deficiencies may be illustrated by 

 the finding that the erythrocyte potassium level of these two 

 strains can be correlated with their ATPase level (Tosteson et al., 

 1960). 



Gale demonstrated and studied from 1947 to 1955 (cf. 1953) 

 the wide occurrence of amino acid transport processes in bacteria. 

 Doudorofr discussed in 1951 the problem of bacterial mutants able 

 to use a given disaccharide but not one of its component sugars 

 despite the presence of appropriate enzymes. He emphasized the 

 possibility that the absence of specific enzymes necessary for per- 

 meation might exclude certain monosaccharides from the cell in- 

 terior. 



Lag periods in the utilization of particular organic substrates 

 have frequently been encountered by microbiologists, and between 

 1951 and 1955 one often finds such comments as these: "Apparently 

 . . . the period of adaptation with the resting cells was the time 

 necessary for elaboration of the system necessary for transferring the 

 substrates across the membrane" (Stone and Wilson, 1952); "It may 

 be that some type of transport or carrier system is being synthesized 

 . . . [during the lag period]" (Barrett et al., 1953); "On this hypo- 

 thesis the adaptive process would consist of the formation of the 

 particular enzyme necessary for the movement of the substrate" 

 (Kogut and Podoski, 1953). 



In 1955 Cohen and Rickenburg (cf. Monod, 1956) brought 

 vigorous new attention to such genetic transport differences in 

 microorganisms, especially with regard to /?-thiogalactoside trans- 

 port in E. coli. Their results showed that inducible transports could 

 probably operate uphill and that they are, in general, not different 

 from other known carrier transports (Cohen and Monod, 1957). 

 Nevertheless a new name permease was recommended for transport 

 processes, or for the inducible part of such processes, or for an 

 enzymatic part. This term has been critically received (see Appendix 

 1 for discussion), and it will be avoided here because it seems to 

 produce an unproductive compartmentalization of communication. 



This comment concerns the unfortunate term permease only. 

 The important potentialities inherent in the absence of a particular 

 transport process in mutants are already evident. For example, if 

 mutants that are unable to transport alkali metal can be identified 



