Comments on Certain Aspects of the 

 Metabolism of Spermatoza 



R. J. FLIPSE 



Dairy Breeding Research Center, Department of Dairy Science, Pennsylvania State University, 

 University Park, Pennsylvania 



In our laboratory we have been interested in the metabolic proc- 

 esses of bovine spermatozoa, interrelationships in the metabolism of 

 different substrates, and methods of regulating or controlling this 

 metabolism. 



Studies of some of the amino acids have been particularly interest- 

 ing. Glycine has been shown to lengthen the time during which 

 sperm remain motile when stored at 5° C (Roy and Bishop, 1954; 

 Flipse and Almquist, 1956). Subsequent studies (Flipse and Alm- 

 quist, 1958) have shown reduced accumulation of lactic acid but 

 no reduction in the fructose which disappeared when the glycine 

 buffer was used. Studies with glycine-C 14 showed that glycine was 

 converted to CO a , although the glycine did not increase oxygen up- 

 take above endogenous levels (Flipse and Benson, 1957). Labeled 

 products from glycine, in addition to CO., , included formate, glyco- 

 late, and glyoxylate. 



These findings suggested the possibility of transamination, and 

 we established this (Flipse and Anderson, 1959) by incubating sperm 

 (and, in some instances, seminal plasma or dialyzed extracts of sperm) 

 with labeled alanine and radioassaying the pyruvate recovered after 

 incubation. In other experiments pyruvate-C u was added as sub- 

 strate and alanine recovered and assayed. Results of such studies are 

 shown in Table I. First of all, interconversion of alanine and pyru- 

 vate was obtained, and secondly, the use of glycine buffer increased 

 the conversion of pyruvate to alanine. Thus we postulated that the 

 beneficial effect of glycine, in reducing lactate accumulation and in 

 extending sperm livability, could be accounted for by the tendency 



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