Multiple Mechanisms of Drug Resistance 159 



occurred with similar preparations made from sensitive cells. 

 Transformation by preparations from resistant cells was lost 

 after treatment with deoxyribonuclease (DNAse). The level 

 of resistance reached in the transformed cells was about that 

 of a first-step mutant, whether the DNA was made from a 

 first-step or a second-step mutant. 



Table III 



Transformation to proflavine resistance in Escherichia coli 36 



We studied the role of the protein fraction, which con- 

 tained some DNA, by substituting other substances for it and 

 adding to the DNA preparation. We found that its place could 

 be taken by duponol, but not by deoxycholate or by rabbit 

 serum (Table III). The protein fraction was found to carry 

 duponol with it, so that its activation of DNA presumably 

 depends on its duponol content. Duponol was shown to 



