In vitro temperature sensitivity of DNA, RNA, and protein syntheses throughout puberty in human testis

To evaluate the optimal temperature for DNA, RNA, and protein syntheses in the prepubertal, pubertal, and postpubertal human testis, the levels of incorporation of 3H-thymidine, 14C-uridine, and 14C-leucine into cultured testicular tissue were studied at 28 degrees C, 31 degrees C, 34 degrees C, 37 degrees C, 40 degrees C, and 43 degrees C. The maximum level of 3H-thymidine incorporation in prepubertal testes occurred at 37 degrees C, whereas the maximum incorporation in the pubertal and postpubertal testes occurred at 31 degrees C. Incorporations of 14C-uridine and 14C-leucine in the three groups were temperature dependent (28 degrees C to 37 degrees C). DNA synthesis by germ cells in the pubertal and postpubertal testes was maximum at 31 degrees C and was impaired at body temperature (37 degrees C), whereas in the prepubertal testis it was temperature dependent with a maximum at 37 degrees C. RNA and protein synthesis in the three groups was temperature dependent at 28 degrees C to 37 degrees C, was depressed at 40 degrees C, and remarkably depressed at 43 degrees C.