Worm Breeder's Gazette 11(4): 79
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
We have been conducting a search for new genes which affect sensitivity to volatile anesthetics. We previously showed that mutations in the genes unc-79(e1068 and ec1) and unc-80(e1272) caused increases in sensitivity to one group of volatile anesthetics ( represented by halothane) but not to two others (represented by enflurane and isoflurane, respectively). We have started screens for mutations which alter sensitivity to isoflurane and enflurane (as well as new mutations altering the response to halothane). Our rationale is that if anesthetics decrease some neurologic function(s), then hypomorphic or loss of function mutations should cause increases in sensitivity. We have started screening at concentrations of anesthetics that are about 50% the concentration that immobilizes N2. At these concentrations N2 is uncoordinated but moving actively. Using these approaches we have identified several new mutations that increase sensitivity to enflurane or isoflurane. We were mildly surprised when five of these new mutations (four with increased sensitivity to isoflurane and one with increased sensitivity to enflurane) were new alleles of unc-79 and unc-80. One of the new alleles of unc-79 appears not to have the increased sensitivities to halothane that e1068 and ec1 exhibit. (Gosh, sounds like an allelic series to me.) Interestingly, in three screens to find other EMS- induced mutations with increased sensitivities to halothane, we have not isolated any new alleles of either unc-79 or unc-80. Anyway, we will test each new allele in anesthetics from all four groups of anesthetics to try to make some sense of all this. If there really are serious allelic differences we plan to make the double heterozygotes to identify any interactions between the alleles. In addition, we have looked for new suppressors of the abnormal sensitivity of unc-79 and unc-80 to halothane. We previously identified the kinked mutants unc-1(X), unc-7(X) (thanks to David Miller), unc-9(X) and unc-24(IV) as suppressors of this phenotype of unc-79 and unc-80. Our screen is to EMS-mutagenize unc-80 (or unc-79) and look for moving F2's at 2% halothane. All the new suppressors we have isolated are X-linked kinked mutants. One of the new kinked alleles is particularly interesting since unc-80 in turn suppresses its kinked phenotype. So far, we have found no strong suppressor of unc-79 or unc-80 which does not have the kinked phenotype. All this has led to an increased interest in the strong suppressor, unc-1. We are actively screening for spontaneously arising unc-1 mutations to begin a transposon tagging approach to cloning this gene. We are using three approaches for this. 1.) Brute force screening for kinky mutants. 2.) Screening for suppression of the unc-79 phenotype in a strain containing mut-6 and ec1. 3.) Screening for loss of the coiler phenotype in a strain containing mut-6 and the dominant coiler allele of unc-1, e1598.