Response of mutagen-sensitive Drosophila melanogaster to hyperthermia and radiation.

In an attempt to understand the mechanism of hyperthermia sensitization of radiation-induced damage, males of 5 mutant mutagen-sensitive strains: mei-41A1, w mus(1)101D1, w mus(1)104D1, y mei-9a, and w mus(1)102D2, representing at least 3 different defects in the DNA-repair pathways were exposed to hyperthermia (38 degrees C for 1 h) and to 1000 R of X-rays. In all of the mutagen-sensitive strains, the radiation-induced dominant lethals were enhanced by the hyperthermia treatment in the 6--8 day brood, which included the meiotic division at the time of radiation, and in the postmeiotic broods. The radiation-induced recessive lethals were also significantly increased by hyperthermia treatment in all the mutagen-sensitive mutants except mei-41A1 in 4--6 day brood. However, mei-41A1 males produced a significant increase of lethals in earlier broods, 0--2 and 2--4 day. The hyperthermia which apparently sensitizes radiation-induced damage by inhibiting DNA and probably chromosome-repair systems, is not specific, at least for 3 different Drosophila repair pathways.