Worm Breeder's Gazette 13(2): 71 (February 1, 1994)
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 reported in the last issue of the Worm Breeder's Gazette (13(1): 46) the identification of multiple loci in C. elegans encoding homologs of the alpha 1 and beta subunits of the mammalian voltage-gated calcium channel. Since then, we have rescued egl-19 ( n582 )IVmutant animals with cosmid clones that contain a homolog of the alpha 1 subunit of the voltage-gated calcium channel. egl-19 is an egg-laying defective mutant that is also long, and uncoordinated. Microinjection of the three cosmids C11E10 , B0496 ,and C48A7 (localized to the contig on LGIV between lin-45 and col-4 )into egl-19 mutant animals yielded F1 progeny that displayed coordinated movement, normal length, and near wild-type egg-laying behavior (a few transformants were slightly egg-laying defective). Each of these cosmids hybridized to our PCR clone of the alpha 1 subunit of the voltage-gated calcium channel. We are currently narrowing the region of rescue with cosmid subclones.
We also reported previously (C. elegans Meeting abstracts, Madison, WI, 1993, pg. 177) that unc-36 mutants, which are defective in the alpha 2 subunit of the voltage-gated calcium channel, are hypersensitive to the calcium channel antagonist verapamil. We have now found that egl-19 animals are also hypersensitive to verapamil. Greater than 95% of egl-19 animals assayed failed to pump in 3 mM verapamil, while wild-type animals displayed only a modest decrease in their pumping rates (about 10-15%).
We have been studying the genetics of egl-19 .We suggested in the last WBG (13(1): 45) that the dominant eat-12 mutations n2368 and ad695 and the recessive egl-19 mutation n582 might be gain-of-function and loss-of-function mutations, respectively, in the same gene. New data support this hypothesis. First, we failed to recover wild-type recombinants among 12,800 progeny of egl-19 ( n582 )/ eat-12 ( n2368 ) unc-24 hermaphrodites, showing tight linkage (<0.05 map units) between n582 and n2368 .Second, two apparent intragenic revertants of n2368 partially failed to complement n582 .
We also wondered if there might be genetic interactions between egl-19 and unc-36 .Preliminary results with single alleles of each locus are as follows: 1) unc-36 ( e251 ); egl-19 ( n582 )double mutants are nearly completely paralyzed, while unc-36 and egl-19 single mutants, although slightly uncoordinated, can move fairly well; 2) unc-36 ; egl-19 /+worms are egg-laying defective, unlike either unc-36 or egl-19 /+animals. These results suggest that unc-36 and egl-19 might interact. We speculate that the protein products of these genes physically interact in muscles involved in egg-laying, as would be expected for the alpha 1 and alpha 2 subunits of the voltage-gated calcium channel.