University of Utah Undergraduate Research Abstracts, Volume 2, Spring 2002

C. elegans Lacking ADARs Fail to Sense Volatile Chemicals

C. elegans Lacking ADARs Fail To Sense Volatile Chemicals Adenosine deaminases that act on RNA (ADARs) are enzymes that deaminate adenosine to inosine in double-stranded RNA (dsRNA). Since inosine is chemically similar to guanosine, it pairs with cytidine. This form of RNA editing can lead to codon changes. ADARs are found in all metazoa and are thought to be most active in neuronal tissue. In C. elegans an adr-1:GFP construct demonstrates that ADR-1 is localized to the nervous tissue. C. elegans has a nerve bundle located at the anterior of the body. This group of neurons senses several types of chemicals including volatile and water soluble chemicals. The worm's ability to sense volatile chemicals plays an important role in its search for food. We have isolated worms containing deletions in the genes encoding ADARs, adr-1 and adr-2, along with the double mutant adr1:adr2. Taking advantage of the worm's ability to sense and move toward chemicals we examined the effect of adr deletions on the worms using chemotaxis assays. Since all 302 neurons in C. elegans have been characterized, a defect in the worm's ability to sense certain chemicals can be directly correlated to a specific neuron. So far, we have studied two neurons called AWA and AWC, which are responsible for sensing volatile chemicals. Chemotaxis experiments with certain volatile chemicals have shown that ADARs act in the AWA and AWC neurons. Assays using a dilution of benzaldehyde produce a chemotaxis index of 0.8 for wild-type and 0.6 for the double mutants. Other volatile chemicals, including: diacetyl, pyrazine, trimethylthiazole, isoamyl alcohol, and 2-butanone, produce similar results with the wild-type worms able to detect and move toward the volatile chemicals more efficiently than the mutants. Future research will determine if ADARs are important in ASE neuron function. The ASE neuron senses water soluble chemicals like, ammonium acetate, sodium chloride, serotonin, and lysine. Chemotaxis assays done with these chemicals will show if ADARs are acting in the ASE neuron of the worm's nerve bundle. Emily R. Herrington Class Standing: Junior Major: Biochemistry E-mail: [e-mail] Faculty Sponsor: Brenda Bass Department of Biochemistry E-mail: [e-mail]