214 moderator: s. hestrin 



respiration in the hypometabolic state depends largely on 

 systems which are insensitive to CO and narcotics. Such systems 

 are not linked to the cytochromes, are not phosphorylating and 

 perhaps do not yield much energy in a useful form. The assump- 

 tion could thus be made perhaps that in the hypometabolic 

 state the organism can afford to use a system which is energeti- 

 cally less effective but which is less sensitive to inhibition. 



Lees : Investigators who have studied diapause in the Cecropia 

 silkmoth have reached a different conclusion. Williams, 

 Shappirio and Schneiderman are now of the opinion that the 

 dormant state is not accompanied by any qualitative change in 

 the metabolic pathway, only by an alteration in the quantitative 

 relationships of the terminal enzyme, cytochrome oxidase, and 

 cytochrome c. CN- and CO-resistance in the diapausing pupa 

 is thought to be the result of the virtual disappearance of cyto- 

 chrome c and the great excess of oxidase. This system, which 

 would also be less effective energetically, would permit the 

 stored reserves of fat and glycogen to be used sparingly. 



Halvorson: From what we know of the enzyme pattern of 

 spores, it appears that while those enzymes needed for energy 

 are preserved, a number of enzymes associated with biosynthetic 

 reactions are acquired during outgrowth. Thus different enzyme 

 patterns would be associated with the formation, maintenance 

 and outgrowth from the dormant state. 



Lees: Is it not possible that the maintenance respiration 

 could be sustained by changes in the classical cytochrome 

 system? 



Avi-Dor: There is really no fundamental difference between 

 the two views. The electron transport system might be the same 

 up to a point, but if cytochrome c were missing, the final 

 electron acceptor the reduced flavin proteins would have to be 

 reoxidized directly by oxygen. Thus the pathway would still be 

 largely the same but would break off at another point. 



Poljakoff-Mayber : Perhaps what is involved here is not so 

 much a complete switchover as a change in proportion between 

 the various pathways. I wonder whether there is not also a 



