Oxidative and Biosynthetic 

 Reactions in Spermatozoa* 



CHARLES TERNER 



Department of Biology, Boston University, Boston, Massachusetts 



At the time the work to be described was started, mammalian sper- 

 matozoa were generally believed to obtain their energy for motility 

 preferentially from glycolytic reactions (Lardy and Phillips, 1941), 

 and a great deal of interest was directed to the study of anaerobic 

 glycolysis, or fructolysis, in spermatozoa of domestic animals (Mann, 

 1954). There was less concern with the aerobic metabolism of sper- 

 matozoa although the studies of Lardy et al. (1945) had produced 

 evidence for the existence of the citric acid cycle in bull spermatozoa. 



In order to investigate nonglycolytic pathways, washed bull sperm 

 were incubated with pyruvate in the Warburg apparatus. When 

 an attempt was made to correlate the observed oxygen consumption 

 with the amount of pyruvate metabolized, it was found that much 

 more pyruvate had disappeared than could have been oxidized by the 

 oxygen taken up. Further analysis revealed that about one-half of the 

 pyruvate which disappeared had been reduced to lactate, so that only 

 the remainder, designated "net pyruvate" could have undergone oxi- 

 dation. It was further observed that on addition of 2,4-dinitrophenol 

 (DNP) the formation of lactate from pyruvate was abolished and 

 that the amount of pyruvate oxidized (net pyruvate) was decreased 

 (Table I). Although in this experiment DNP did not alter the rate 

 of respiration, the ratio 2 /net pyruvate was increased to the ex- 

 tent that the pyruvate disappearing could be assumed to undergo 

 complete oxidation. The inhibition by DNP of the metabolism of 

 pyruvate is unusual for animal tissues in which stimulation is usu- 

 ally observed, and also contrasts with the stimulation by DNP of the 



* Supported by Grant No. RG 7078 (formerly RG-4963) from the National In- 

 stitutes of Health, United States Public Health Service. 



