Taste reception

Schmale H., Holtgreve-Grez H. and Christiansen H. (1990). Possible role for salivary gland protein in taste reception indicated by homology to lipophillic-ligand carrier proteins. Nature 343, 366-369. 

Ye, Q., Heck, G. L. and DeSimone, J. A. The anion paradox in sodium taste reception resolution by voltage-clamp studies. Science 254 724-726,1991. 

The current accepted theory suggests that a bitter compound and a sweet compound bind independently at specitic receptors. This situation will be referred to as "independent" in this report. The data to follow will demonstrate that a bitter compound and a sweet compound bind at the same receptor in a competitive manner. Therefore, this situation will be referred to as "competitive" in this report. Which theory was the functioning mechanism of taste reception should be determinable when one measured the taste intensities of mixed solutions of bitter and sweet tasting compounds. In this experiment the mechanism could be predicted to elicit a considerable difference in taste intensity and response that was varying based on the final concentration of each component. The "independent" receptor mechanism would be expected to yield data in which the intensities of bitter and sweet would be unaffected by mixing the two tastes, no matter what the concentration. On the other hand, with the "competitive" receptor mechanism one would expect both flavors to become altered, i.e., one stronger and the other weaker, as component concentrations varied the latter would occur because of competition of the substances for the same site. 

In biological taste reception, taste substances are received by the biological membrane of gustatory cells in taste buds on tongue (Figure 1). Then the information on taste substances is transduced into an electric signal, which is... 

One method to realize the taste sensor may be the utilization of similar materials to biological systems as the transducer. The biological membrane is composed of proteins and lipids. Proteins are main receptors of taste substances. Especially for sour, salty, or bitter substances, the lipid-membrane part is also suggested to be the receptor site [6]. In biological taste reception, taste stimulus changes the receptor potentials of taste cells, which have various characteristics in reception [7,8]. Then the pattern constructed of receptor potentials is translated into the excitation pattern in taste neurons (across-fiber-pattem theory). 

The researchers then studied umami taste reception by measuring the relative lick rates of the different mouse strains with different quantities of MSG in the feeding solution. Note that the solutions also contained inosine monophosphate (IMP), a strong potentiator of umami taste reception (and a common ingredient in ramen soups, along with MSG), and ameloride, which suppresses the pleasant salty taste imparted by the sodium of MSG. The results are shown in the graph. 

In contrast to visual perception, where the sole stimulus is a photon, and even in contrast to olfaction with its structurally much more diversified stimuli, taste perception is exceptional, because the taste stimuli differ even more than odorants in size and chemical complexity, ranging from H+ ions to carbohydrates, amino adds, and proteins. Consequently, taste transduction mi t involve different mechanisms for different stimuli. In the ihesus monkey, taste reception has been located anatomically to defined loci at either the anterior or the posterior part of the tongue. 

Taste reception varies enormously across vertebrates. Because the taste perception of a species is related essentially to its diet and environment, the studies of the variation of genes, which control taste reception among vertebrates will contribute greatly to our understanding of the relationship between the adaptation of organisms and the diversity of environmental chemicals. 

Yasuoka A, Okada S, Abe K (2006) General logic for taste reception. Jikken Igaku Suppl Yodo-sha 125-30 (in Japanese)... 

Since sweet natural products often co-occur in complex mixtures with bitter- and/or neutral-tasting analogs, it is germane to mention briefly some of the presently held views on the mechanism of sweet taste reception. Although sweet taste chemoreception is thought to be mediated by proteinaceous receptor sites located on the microvillus membrane of taste cells of the... 

The evolutionary transition from water to land has resulted in an expansion of the chemoreceptor genes, most likely in response to the multitude of airborne odorants (Bargmann 2006). Organisms that frequently change between aquatic and terrestrial environments (e.g., amphibians) appear to have chemosensory systems for perception of both water-soluble as well as volatile odorants (Freitag et al. 1995). Soluble and volatile chemicals can also be perceived by aquatic and terrestrial crustaceans, respectively (e.g., Hansson et al., Chap. 8). However, at least in terrestrial peracarids, taste reception of odorants appears to be mediated by liquids (Seelinger 1983 Holdich 1984), just as food-smelling of terrestrial mammals under water is mediated by air bubbles (Catania 2006). 

Johnsen and Teeter (1982) demonstrated that bullheads could be conditioned to respond to chemical concentration differences presented across their maxillary barbels. These structures contain taste receptive fields innervated by the facial (VII) nerve. Fish responded to concentration differences as small as 10%, but the minimum discernible difference in concentration depended on the concentration of the stimulus. At higher concentrations, larger differences between the left and right barbels were required for the fish to show an appropriate behavioral response. 

Gothilf, S., Galun, R. and Bar-Zeev, M. (1971) Taste reception in the Mediterranean fruit fly Electrophysiological and behavioural studies. J. Insect Physiol., 17, 1371-84. 

Taste quality and intensity are dependent not only on a compound s structure but on other taste reception parameters temperature, pH and the presence of additional sweet or non-sweet compounds. 

---