Worm Breeder's Gazette 13(5): 39 (February 1, 1995)
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.
Universitv of Utah, Dept. of Biology. UT 84112
Our goal is to identify proteins that function at all synapses. These include proteins that are involved in svnthesis, packaging, transport and the release of neurotransmitters into the synaptic cleft, as well as proteins involved in the recycling of synaptic vesicles. Initially we screened for mutants that behaved as if they were defective for both GABA and acetylcholine function: 11 genes were defined by this approach. One drawback with such a screen is that it will fail to identify lethal mutations. We have developed a screen which can potentially identify lethal mutations that interfere with neurotransmission. Aldicarb is a pesticide that inhibits the breakdown of acetylcholine in the synaptic cleft. The resulting accumulation of acetylcholine in wild-type worms results in paralysis. whereas worms lacking or having reduced acetylcholine transmission are resistant to the drug and continue to move. It was noted that many of the genes uncovered in the behavioral screen conferred resistance to aldicarb as double heterozygotes with n2813. an allele of unc-13 (for example unc-13/+: snt-l/+). Apparently neurosecretion is very sensitive to the dosage of proteins required for this process. This sensitivity allowed us to screen for haploinsufficient mutations in a background sensitized by the unc-13 mutation. We mutagenized wild-type males and crossed them to a strain containing unc-13 (n2813) (see Figure below). In the Fl we picked aldicarb-resistant individuals. Lethal mutations in genes that are essential to synaptic function are maintained as aldicarb resistant heterozygotes. We are interested in two classes of mutations: The first class are lethal mutations, identified as strains that are resistant to aldicarb when unc-13 is heterozygous, and also throw lethal progeny. The second class are homozygous viable aldicarb-resistant mutations that can be separated from the unc-13 mutation. Of 2336 genomes scored. we uncovered 62 possible lethal mutations and 61 homozygous viable aldicarb-resistant mutations. In the homozygous viable class we found both uncoordinated and wild-type mutants. All of these strains have satisfied preliminary criteria for synaptic function mutants and we are confident that our screen will be successfill in uncovering genes of interest. One mutation pulled out of the modified screen has been shown by noncomplementation to be an allele of unc-26, mutations of which are known to be resistant to Aldicarb (J. Rand, personal comm.).