2023-10-13 06:00:06
The discovery of a sixth taste, beyond sweet, salty, bitter, sour and umami, is a continuation of the taste explorations begun by the Japanese scientist Kikunae Ikeda in the early 1900s. This advance, led by a team of researchers from the USC Dornsife College of Letters, Arts and Sciences, highlights the receptivity of the tongue to ammonium chloride (The ammonium ion (formula NH4+) is a polyatomic ion with a positive electrical charge (it is. ..), via the same protein receptor that detects acidity.
Image d’illustration Pixabay
Emily Liman, a neuroscientist at USC Dornsife, and her team observed how ammonium chloride, a component of Salmiak salt used in northern European confectioneries, interacts with the protein receptor OTOP1, previously identified as a detector (A detector is a technical device (instrument, substance, material) which changes…) acidity. Their study, published in Nature Communications, reveals that ammonium chloride, by modifying the acid concentration of cells, activates the OTOP1 channel, thus generating a taste response .
By culturing human cells expressing the Otop1 gene, researchers found notable activation of the OTOP1 channel in the presence of ammonium chloride, even surpassing the response to acids.
In addition, exposure to ammonium chloride induced a significant increase in action potentials in the taste cells of normal mice. , while those lacking OTOP1 remained indifferent to this salt. This observation was reinforced by observations on the behavior of mice faced with an ammonium chloride solution, revealing a clear aversion in specimens equipped with OTOP1, unlike their counterparts lacking this protein.
Attention then shifted to the varied sensitivity of OTOP1 channels across different species. Indeed, receptivity to ammonium chloride varies, suggesting an evolutionary adaptation to the environment of each species (In the life sciences, the species (from the Latin species, “type”…). For example, the Increased sensitivity in chickens might be linked to the avoidance of ammonium present in waste, unlike fish (Pisces is a constellation of zodiac crossed by the Sun from March 12 to 18…) who encounter this element less in water.
Experiments carried out on genetically modified mice confirmed the key role of OTOP1 in the perception of ammonium chloride.
Credit: Nature Communications (2023).
This discovery also identified a specific amino acid in the structure of OTOP1, crucial for the detection of ammonium chloride. A detail that Liman believes may have played a vital role in the survival of species through evolution.
Future research aims to explore the conservation of this sensitivity within the OTOP protein family, particularly in other parts of the body such as the digestive tract. The study opens the door to the possibility of integrating ammonium chloride into the list of basic tastes, which might thus increase from five to six.
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