Inactivation of wild-type and rad mutant Caenorhabditis elegans by 8-methoxypsoralen and near ultraviolet radiation.
Survival of wild-type and four radiation-sensitive (rad) mutants of the nematode Caenorhabditis elegans was determined after near-UV irradiation in the presence of 8-methoxypsoralen (8-MOP). Three sets of inactivation profiles were generated for each strain by irradiating synchronous populations of either early embryos, late embryos or first-stage larvae (L1s). Late embryos were consistently the most sensitive. Curiously, none of the four rad mutants were even moderately hypersensitive. Split-dose experiments indicated that DNA-DNA crosslinks were primarily responsible for lethality. Crosslink induction and repair were determined using two different assays. In both cases, little if any repair was observed in wild-type. This lack of repair thus explains why the rad mutants were not hypersensitive to 8-MOP photoinactivation. Since early embryos undergo extensive cell cycling, their resistance to 8-MOP photoinactivation suggests that replication is highly refractory to both monoadducts and crosslinks, as has been demonstrated previously for UV radiation-induced photoproducts (Hartman et al., 1991, Mutat. Res., 255, pp. 163-173).
Hartman
P S
PS
Department of Biology, Texas Christian University, Fort Worth 76129.
Marshall
A
A
D000818:Animals; D002107:Caenorhabditis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*; D004247:DNA / Q000187:drug effects / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000528:radiation effects; D047108:Embryonic Development; D007814:Larva; D008730:Methoxsalen / Q000494:pharmacology*; D009154:Mutation; D014466:Ultraviolet Rays
D004247:DNA; D008730:Methoxsalen