Oxidative stress pretreatment increases the X-radiation resistance of the nematode Caenorhabditis elegans

pre-exposure of wild-type Caenorhabditis elegans to oxygen conferred a prot ective effect against the lethality imposed by subsequent X-irradiation. In contrast, two mutants (rad-1 and rad-2) that are UV and ionizing radiation hypersensitive but not oxygen sensitive, did not exhibit this adaptive res ponse. To explore the molecular basis of protection, the expression of seve ral key genes was examined using Northern blot analyses to measure mRNA lev els. In the wild-type, expression of the heat shuck protein genes, hsp16-1 and hsp16-48, increased dramatically after incubation under high oxygen. Ex pression of two superoxide dismutase genes (sod-1 and sod-3) was relatively unaffected. Unlike the wild-type, the basal levels of these four genes wer e significantly lower in the rad-1 and rad-2 mutants under atmospheric cond itions. These genes were partially induced in response to oxidative stress. These data suggest that at least a portion of the hypersensitive phenotype of rad-1 and rad-2 may be attributed to inappropriate gene expression. (C) 1999 Elsevier Science B.V. All rights reserved.