Background - Mutations in Taste
Taste sensations are usually divided into four qualities: bitter, sweet, salty, and sour. This categorization is based on human perception, but animal data suggest existence of similar qualities. There is at least one additional glutamate-like ('umami') taste quality and one additional chemosensory mechanism - irritation, transmitted via the trigeminal nerve. Taste sensations arise in the taste receptor cells that are synaptically connected to afferent endings of gustatory nerves, which in turn conduct the taste information to the nucleus of the solitary tract of the medulla; from there the information is further transmitted to other brain structures responsible for higher levels of analysis and integration with other brain activities. Thus, taste sensations are part of the complex ingestive behavior. In addition to peripheral perception, taste-related behavior is also affected by motivational, learning, metabolic, and pharmacological factors. Hence, phenotyping ingestive behavior can identify deviations in several different physiological systems. In the proposed screen, we utilize this as a strength allowing us to detect deviations in multiple systems using simple and reliable tests.
Genetic determination of taste - related behavior has been documented in several species, including mice [235-238, 249]. Taste-related behavior is most likely determined by multiple loci, a few of which have been described, but most are still unknown [239-243]. However, previous studies have demonstrated that alteration of a single gene can produce an easily detectable and robust effect on taste-related behavior, results which justify a chemically induced mutagenesis approach.
