OXIDATIVE AND BIOSYNTHETIC REACTIONS 97 



bull spermatozoa is now possible. That the breakdown of carbohy- 

 drate by spermatozoa results in the production of ATP for motility 

 and also has a sparing effect on endogenous lipids because of the 

 preferential oxidation of carbohydrate has long been recognized. 

 Most sperm physiologists will readily agree that the breakdown of 

 carbohydrate by spermatozoa not only results in the production of 

 ATP but also has a sparing action on the endogenous lipid reserves 

 owing to the preferential oxidation of carbohydrate. Beyond that, 

 however, there is a long-standing belief, evident also in the present 

 symposium, that the energy generated by glycolysis is utilized ex- 

 clusively in the support of motility, disregarding and even discount- 

 ing the possibility of the utilization of ATP in reactions resulting in 

 the maintenance of some of the constituents of spermatozoa. The 

 work that has been described shows that the effect of carbohydrate 

 in maintaining endogenous lipid reserves is more than a sparing of 

 the lipid. Rather it is due to an active synthesis of the lipids since we 

 have seen that carbohydrate carbon appears in the glycerol moiety of 

 the lipids of isolated spermatozoa on incubation under both aerobic 

 and anaerobic conditions. 



It has also been found that there is, in bull spermatozoa at least, 

 a mechanism by which acetyl coenzyme A may be formed from car- 

 bohydrate even in the absence of oxygen and that this may be utilized 

 in fatty acid biosynthesis. 



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Korkes, S., A. del Campillo, I. C. Gunsalus, and S. Ochoa. 1951. Enzy- 

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Lardy, H. A., and P. H. Phillips. 1941. Phospholipids as a source of en- 

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