Wild-type animals largely arrest development if L1's are placed on NG plates containing 30 mM or greater concentrations of the methylxanthin-derivative caffeine. Eleven mutants have been isolated among the F2 progeny of EMS-mutagenized animals in which this developmental delay is less severe. Although caffeine delays development in these mutants, most attain adulthood and produce progeny. Wild-type and mutant L1's have been incubated on plates containing between 5mM and 40mM caffeine and their lengths measured after three days. Increasing caffeine concentrations reduced length in a roughly linear fashion. All eleven mutant strains were approximately as resistant as N2, as judged by this criterion. The mutations are recessive and define two new genes, named
caf-1 and caf- 2. There are eight alleles of
caf-1 and three alleles of
caf-2. Linkage testing shows
caf-1 is on LGII. It is left of
dpy-10 as indicated by a 3F cross using
dpy-10 and
unc-4. Two factor crosses place it 39 mu away from
unc-4 and 21 mu away from
sqt-2. You LGII fanatics realize that this is way out in left field. The second gene is right of
unc-13, as indicated by a 3F cross using
dpy-5 and
unc-13. A 2F cross places it approximately 6.7 mu right of
dpy-5. This agrees well with observation that
caf-2/nDf24 heterozygotes are resistant to caffeine. Caffeine-resistant strains of Escherichia coli are often altered in their lethal responses to UV and ionizing radiations (Grigg, 1967. Mutat. Res. 4, 553; Delvaux and Devoret, 1969. Mutat. Res. 7, 273) . It was hoped a similar situation would exist with C. elegans, thus providing a selection for additional rad mutants. Preliminary inactivation data suggest that this is not the case. We hope to further characterize the mutants by: 1) assaying sensitivities to other methylaxanthin derivatives, including theophylline; 2) constructing a
caf-1; utant and determining its sensitivities; and 3) testing for suppression of all alleles by
sup-7; and 4) assaying for metabolism of caffeine in N2 and the caf mutants. Suggestions for additional experiments are most welcome.