Effect of temperature on incorporation of l-lysine-U-C¹⁴ into testicular proteins

¹ Department of Pharmacology and Therapeutics, Stritch School of Medicine, and Graduate School, Loyola University, Chicago, Illinois

The incorporation of l-lysine-U-C¹⁴ into proteins of slices of rat testis, liver, kidney, and spleen has been investigated following a 1-hr incubation period at temperatures of 20, 26, 32, 37.5, and 44 C. In the testis, maximal incorporation of labeled lysine into protein occurred at 32 C, whereas in the liver, kidney, and spleen the maximal incorporation of isotope into protein occurred at 37.5 C. The data obtained indicate that the enzymatic systems involved in the incorporation of labeled lysine into proteins of the rat testis are more heat labile than those of rat liver, kidney, and spleen. It is suggested that the increased heat lability of the protein-synthesizing systems of the testis may offer a partial explanation for the deleterious effects of temperature on spermatogenesis occurring in cases of cryptorchism.