DANIELLI • H. T. KOCH 



J. F. Danielli. I agree that acetylcholine may act upon a trigger mechanism in some 

 instances of active transport. 



L. M. Rinaldini. A single protein molecule might absorb a large number of ions and 

 so transport many molecules of NaCl in a single contraction. In this case the i : i 

 ratio between ATP and NaCl could still hold, but the number of molecules of 

 ATP involved would provide enough energy to contract the protein molecule. 



J. F. Danielli. I agree with this. 



L. M. Rinaldini. Cinematography shows that cells are in a continuous state of 

 flux, and that mitochondria move very actively within them, no doubt causing a 

 stirring. The cell membrane and mitochondria are seen to stretch and contract very 

 actively. Perhaps by constructing dynamic diffusion models some of the discrepan- 

 cies between the figures obtained with models and with living cells might disappear. 



J. F. Danielli. Studies on monolayers show that even with stirring there is a relatively 

 unstirred layer close to the membrane. However the error introduced by this into 

 calculations of permeability constants has been shown to be negligible unless the 

 oil/water partition coefficient of the penetrating molecule is of the order of i or more. 

 The molecular species we are considering here have lower coefficients. 



If proteins are actively contracting on a protoplasmic surface they are likely to 

 cause movement of that surface. This may indeed be the main method of proto- 

 plasmic movement, as has been suggested by Goldacre (1952, Int. Rev. Cytol. 1, 

 135-164-) 



K. E. Cooper. Does the absorption of red cell antibodies, or the agglutination of red 

 cells by virus particles (e.g. influenza), or the treatment of red cells by enzymes 

 (e.g. trypsin) affect permeability to ions? 



J. F. Danielli. The patches on red cells specific for viruses are worthy of attention in 

 this connexion, but I am not aware of any experiments bearing on this point. Pro- 

 longed treatment of red cells with proteases or lipases causes haemolysis, presumably 

 owing to increased permeability to ions. The action of antibodies formed to known 

 membrane components, such as cholinesterase, would be of great interest. 



R. D. Keynes. When basic dyes are applied to the inside of the gill and fail to inhibit 

 sodium transport, do they also fail to affect oxygen consumption? 



H. Koch. We have not so far investigated this point. 



J. F. Danielli. Pyocyanine has been shown to uncouple oxidation and phosphoryla- 

 tion. Is that true of the other dyes you used ? 



H. Koch. DNP has no influence on salt transport when applied to the outside of the 

 gills. Therefore it seems unlikely that the effect of pyocyanine outside the gill is due 

 to an uncoupling of oxidation and phosphorylation. Recently Judah and Ashman also 

 described an interference of basic dyes with aerobic phosphorylation. It is certainly 

 true that the interpretation of the action of basic dyes as anti-cholinesterases needs 

 the support of more specific inhibitors of cholinesterases such as physostigmine, etc. 



E. W. Temm. At what pH were the experiments with 2-4 DNP carried out? Is this 

 responsible for its action by influencing penetration? 



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