Pyrimidines and the X-ray response of Tribolium confusum Duval.
Radiosensitizing effects of incorporation into DNA of the halogenated pyrimidines 5-bromouracil or 5-iodouracil, or their nucleosides (BUdR and IUdR), have been demonstrated in a variety of cell types. The results indicate that these antimetabolites influence lethality in x-irradiated adult Tribolium. At relatively low concentrations in the medium, BUdR and IUdR exhibit toxicity 3 to 5 weeks after transfer of beetles to analog-containing medium. Toxicity of IUdR on nonirradiated adults is less pronounced than that of BUdR and is slower to develop. Analog-treated Tribolium exposed to 7 kR, which is sublethal for adults in normal medium, die much earlier than those treated with analog alone or with lethal doses of x-rays alone. Transfer of beetles to normal medium after 3 weeks or less in the presence of analog virtually eliminates lethality attributable to the analog. X-irradiation at the time of transfer, however, leads to high mortality, and the amount of mortality appears to be a function of the duration of analog treatment. Insects grown in medium containing uracil or thymine exhibit the same survival as those reared in unsupplemented medium. Two weeks after 7 kR of irradiation a sharp decline in survival is seen in both uracil- and thymine-treated groups.
Hogan
G R
GR
Department of Physiology and Biophysics, University of Illinois, Urbana, Illinois, USA.
D000818:Animals; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D011743:Pyrimidines / Q000378:metabolism*; D011829:Radiation Dosage; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage*; D013534:Survival; D015996:Survival Rate; D014231:Tribolium / Q000502:physiology* / Q000528:radiation effects*; D014965:X-Rays
D011743:Pyrimidines; D011838:Radiation-Sensitizing Agents