Sweet, bitter, sour, salty, umami and, now alkaline. The list of flavors that an organism is capable of perceiving we have to expand it up to six thanks to the fruit fly. A team of scientists has managed to demonstrate that this small and common insect is capable of detecting the presence of a high pH as survival mechanism through receptors that they have in the mouth and on the legs.
The results of the research, published in the journal Nature Metabolism, thus confirm the existence of a sixth taste that had already been detected through other insects, and that other animals are probably also capable of perceiving. It seems more difficult for human beings to preserve this taste ability to detect alkaline flavor, since it responds, fundamentally, to a natural system to discern between potentially toxic substancessomething that we have been losing evolutionarily.
Researchers from the University of California and the Monell Center for Chemical Senses (United States), in collaboration with the Chinese Academy of Sciences, set out to explore the molecular identities of the taste receptors that detect the basic pH of food using the fruit fly (Drosophila melanogaster) as a model, using CRISPR technology and different assays.
What is alkaline taste and why is it important?
We have already mentioned on occasion the importance of the pH scale in feeding. roughlyIt is enough to remember that this scale measures the degree of acidity of a certain substance (for example, food), with a range of figures, from 0 to 14. Zero marks the maximum acidity, a low pH; the 14 indicates the opposite, a very high or basic pHcorresponding to substances alkaline.
The two extremes make life difficult and therefore are also related to toxic elements that an organism must avoid. He sense of taste nowadays we associate it with pleasure, but in its origin it responds to a natural mechanism through which we can detect dangerous foods that we should not ingest. Animals better preserve this system which, as the researchers themselves indicate, acts as a sentinel.
The fruit fly is a regular research subject in laboratories, and specialists such as Craig Montell, who is involved in the work, has spent years studying their sensory receptors. This insect, like many others, manages to identify flavors both through the lip of the mouth and directly through the legs. In this way they can detect, through taste, foods and also alkaline surfaces, in order to avoid them.
genetically modified flies
Thanks to CRISPR technology, the researchers worked from flies that were missing a gene linked to the senses, subjecting them to different experiments. For example, exposing them to pure glucose -sweet taste- and glucose with caustic soda -sodium hydroxide, alkaline base-. The unmodified flies avoided the second, but the specimens that had blocked a certain genedid not show the same aversion for the alkaline substance.
After various tests with different flies and selected substances, as explained in Subjectto rule out reasons other than that basic taste perception, the scientists renamed the aforementioned gene, CG12344, as gene alkaconcluding that its function is detect alkalinity of a substance, the so-called now sixth alkaline taste.
Although our sense of taste works through very similar mechanisms, with taste cells detecting flavors and sending signals to the brain to act accordingly, we don’t have the same receptors that these insects
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However, scientists celebrate achievements of this work; “Taken together, our discovery of Alka as an alkaline taste receptor lays the foundation for future research on alkaline taste sensation in other animals.”
Photos | Katja Schulz – brgfx – freepik
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