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Biology of Reproduction, Vol 1, 200-206, Copyright © 1969 by Society for the Study of Reproduction

Metabolism of Bovine Semen

XX. Role of ammonia in interactions between the citric acid and urea cycles

R. W. DIETZ 1, and R. J. FLIPSE 1

1 Department of Dairy Science, The Pennsylvania State University, University Park


The effects of ammonia on sperm respiration, the nature and amount of metabolites formed, and overall urea cycle activity have been investigated in bovine spermatozoa with at least four replications involved in each comparison. Oxygen uptake and the specific activity of 14CO2 produced from pyruvate-2-14C by washed bovine spermatozoa declined as a result of increased levels of ammonia; the compound tentatively identified as argininosuccinate increased as ammonia concentration was increased. Ornithine-14C conversion to 14CO2 was inhibited about 50% and arginine production was elevated considerably when ammonia concentration was 100mM. Radioactivity in proline and agr amino-dgr-hydroxyvalerate increased in the presence of ammonia. Rabbit sperm but not bull sperm responded to ammonia by conversion of citrulline-ureido-14C to 14CO2 in the absence of added urease. Rabbit sperm also appeared to have higher concentrations of urea cycle enzymes than did bull sperm. The activity of carbamyl phosphatase synthetase, ornithine carbamyl transferase and arginase was 0.12, 0.8, and 0.8 units/mg of spermatozoal protein, respectively, for bulls, and 0.41, 3.2, and 9.8 units/mg respectively for rabbits. No arginine synthetase activity was detected in acetone powders of semen from either species. Enzyme location was established using acetone powders of semen fractions. Arginase and carbamyl phosphate synthetase were present mainly in the midpiece-tail fraction while ornithine carbamyl transferase was associated with both head and midpiece-tail fractions. The data collected on metabolic products from labeled substrates, the measurement of overall urea cycle activity and the assays of three urea cycle enzymes indicate the presence of a functioning urea cycle in bovine spermatozoa.

Submitted on February 17, 1969






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Copyright © 1969 by the Society for the Study of Reproduction.