Enzymes involved in DNA synthesis in the testes are regulated by temperature in vitro.
OBJECTIVE
Temperature is considered to be an important local regulating factor of testicular function. We investigated whether a high temperature would affect the activity of DNA polymerases alpha, beta, and gamma (EC2.7.7.7) and DNA topoisomerase I in the testes which are required for germ cell differentiation.


METHODS
An in vitro rat testis tissue culture system was used to evaluate the activity of DNA polymerases alpha, beta, and gamma and DNA topoisomerase I after incubation at 31 and 37 degrees C. The expression of proliferating cell nuclear antigen was evaluated immunohistochemically in the testis.


RESULTS
Incubation at 37 degrees C significantly reduced the activity of all four enzymes as compared with incubation at 31 degrees C. Reducing the temperature to 31 degrees C after prior incubation at 37 degrees C partially restored DNA polymerase alpha activity. Expression of proliferating cell nuclear antigen demonstrated a reduction in DNA synthesis in the seminiferous tubules after incubation at 37 degrees C CONCLUSION: These findings indicate that a high temperature of 37 degrees C reduces the activity of the enzymes involved in the testicular synthesis of DNA which may cause the impairment of spermatogenesis.
Fujisawa
M
M
Department of Urology, Kobe University School of Medicine, Japan.
Hayashi
A
A
Okada
H
H
Arakawa
S
S
Kamidono
S
S
D000818:Animals; D046508:Culture Techniques; D004247:DNA / Q000096:biosynthesis*; D004256:DNA Polymerase I / Q000378:metabolism; D004257:DNA Polymerase II / Q000378:metabolism; D004258:DNA Polymerase III / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013696:Temperature; D013737:Testis / Q000166:cytology / Q000201:enzymology*
D018809:Proliferating Cell Nuclear Antigen; D004247:DNA; D004256:DNA Polymerase I; D004257:DNA Polymerase II; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D004264:DNA Topoisomerases, Type I