Worms shed light on our ability to smell food
suggests new ways of regulating the behaviours that allow us to
smell food, learn, and remember.
Brenda Bass, professor of biochemistry at the university school of medicine together with Leath Tonkin, a graduate student in her lab, published their findings in the 5 December issue of the journal Science.
With the help of a tiny worm, C. elegans, Bass and Tonkin discovered that ADAR, an enzyme abundant in the nervous system, interacts with a pathway called RNAi (RNA interference). When it is functioning properly, RNAi, which was discovered in 1998, ensures that certain genes are turned on in some cells and turned off in others.
C. elegans that have mutations in their ADAR genes have behavioural defects, according to Bass. For example, mutant worms that lack ADARs have trouble finding food. When placed near food a normal worm crawls quickly to the food but an ADAR mutant may crawl in a completely different direction. To see if ADAR functions were related to the RNAi pathway, Bass and Tonkin made strains of the worm with mutations in both the ADAR genes and in genes required for RNAi.
"Remarkably, in these worms, the behavioural defects associated with the mutations in the ADAR genes were eliminated," Bass said.
"This suggests that ADARs intersect with the RNAi pathway and that many of the behavioural defects of ADAR mutants are caused by aberrant RNAi."
RNA is a nucleic acid that is an essential component of all cells. In a process called transcription, the information in our DNA genes is passed to RNA. A second process called translation allows the information in RNA to be turned into protein. Typically, one gene has the information for one protein, but with the help of "editing" enzymes such as ADAR, multiple proteins can be made from one gene.
ADARs enable RNA to produce different proteins by altering the sequence of nucleotides that contain the information for making a protein. This had previously been considered as ADARs' most important function, but the new research from Bass and Tonkin implies that ADARs might perform a realm of other functions.
