We have previously shown that mutations in the neuronal syntaxin gene unc-64 profoundly
alter the volatile anesthetic (VA) sensitivity of C. elegans. We found that two
hypomorphic unc-64 alleles confer hypersensitivity to the VAs isoflurane and halothane but
that a third unc-64 hypomorph is VA resistant. The difference between the isoflurane
EC50's (the concentration where the effect on locomotion is half maximal) of the
hypersensitive and resistant alleles is over 30-fold. In order to understand the molecular
mechanisms of syntaxin's regulation of anesthetics, we are searching for genes that
interact with the syntaxin gene. Thus, we initiated a screen for suppressors of the
locomotion defect of unc-64(e246lf). The F2 progeny of EMS treated unc-64(e246) were
screened for better moving animals. We
have screened 14,400 F1 genomes and have established seven independent strains that
clearly move better than e246. The suppressor strains moved between 6-8 times faster than
e246 as measured from movies taken of them crawling on agar without food. Outcrossing of
the seven strains revealed three segregating phenotypes, loopy movers (4 strains), jerky
movers (1 strain), and long worms (1 strain); one strain segregated no obvious visible
phenotype. We are currently determining whether these phenotypes are in fact those of the
e246 suppressors. A similar screen has been performed by Owais Saifee in Mike Nonet's lab.
They also isolated loopy e246 suppressors. We tested the anesthetic sensitivity of two of
their loopy strains, js126 and js127e246. Both strains were anesthetic resistant with
EC50s more than twice that of N2. This confirms that this is a reasonable approach towards
finding "anesthesia genes". We are currently determining the anesthetic
sensitivity of the suppressors isolated in our screen.