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DISCUSSION 



Davis: I gather that these studies on adaptive enzyme formation were 

 carried out under conditions without growi;h, relying on nitrogen sources 

 within the cell. Have you studied the effect of your compounds on 

 adaptation under conditions of gro\\i;h ? 



Slonimski: We have started experiments on Esch.coli which is probably 

 the best organism for such a study. 



Davis: Your system in yeast has not been tested with growing cells? 



Slonimski: Adaptive enzyme formation (cytochrome oxidase and 

 maltozymase) was studied in the absence of growth and in the absence 

 of cellular multiplication. Mutation studies were carried out, however, 

 with cells growing exponentially in full medium. Cytochrome oxidase 

 synthesis in yeast has a preferential character. ^Vhen, during adaptation 

 taking place in glucose buffer, one starts growth by addition of growth 

 factors and a nitrogen source one gets first a temporary inhibition. 

 Instead of getting a higher rate of synthesis one gets a lower one. This 

 inhibition is resumed in about an hour. 



Pollock: Did you get a completely parallel effect with these substances, 

 cofactor E and cofactor T? 



Slonimski: T is inhibitory in maltozymase, in cytochrome oxidase and 

 in the euflavine-induced mutation (i.e. it inhibits the transmission of 

 the normal genetic material). With respect to erythrose derivatives, we 

 are not yet certain about this, but the substance that works on malto- 

 zymase may be different from the one that works on respiratory adapta- 

 tion or the induced "petite" mutation. 



We have preparations that stimulate cytochrome oxidase formation 

 and are not active on maltozymase ; and vice versa, we have one substance 

 which stimulates maltozymase adaptation and is inactive on cytochrome 



