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Archive - Aug 20, 2013

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Multiple Genes Determine How People Taste Sweeteners

Genetics may play a role in how people's taste receptors send signals, leading to a wide spectrum of taste preferences, according to Penn State food scientists. These varied, genetically influenced responses may mean that food and drink companies will need a range of artificial sweeteners to accommodate different consumer tastes. "Genetic differences lead to differences in how people respond to tastes of foods," said Dr. John Hayes, assistant professor, food science, and director of the sensory evaluation center at Penn State. Based on the participants' genetic profile, researchers were able to explain the reactions of subjects in a taste test when they sampled Acesulfame-K -- Ace K -- in the laboratory. Ace K is a man-made non-nutritive sweetener commonly found in carbonated soft drinks and other products. Non-nutritive sweeteners are sweeteners with minimal or no calories. While some people find Ace K sweet, others find it both bitter and sweet. The researchers, who reported their findings online on April 18, 2013 in the journal, Chemical Senses, said that variants of two bitter taste receptor genes -- TAS2R9 and TAS2R31 -- were able to explain some of the differences in Ace K's bitterness. These two taste receptor genes work independently, but they can combine to form a range of responses, said Alissa Allen, a doctoral student in food science, who worked with Dr. Hayes. Humans have 25 bitter-taste receptors and one sweet receptor that act like locks on gates. When molecules fit certain receptors like keys, a signal is sent to the brain, which interprets these signals as tastes -- some pleasant and some not so pleasant, Allen said. In another study published in July 2013 in the journal Chemosensory Perception, Allen had 122 participants taste two stevia extracts, RebA -- Rebaudioside A -- and RebD -- Rebaudioside D.

New Hypothesis for How Anthrax Toxins Escape Intracellular Endosome

A new hypothesis concerning a crucial step in the anthrax infection process has been advanced by scientists at the National Institute of Standards and Technology (NIST) and the U.S. Army Medical Research Institute for Infectious Diseases (USAMRIID) at Fort Detrick, Maryland. The research teams have explored the behavior of the toxins that rapidly overwhelm the body as the often-fatal disease progresses. Their findings suggest a new possible mechanism by which anthrax bacteria deliver the protein molecules that poison victims. Anthrax is easily weaponized; the findings could help lead to a more effective cure. The results were published online on August 8, 2013 in the Journal of Chemical Physics. Anthrax bacteria kill by releasing three toxins that work in concert to destroy cells. One toxin, called PA, attaches to the cell membrane, where its surface serves as a sort of landing pad for the other two toxins, called LF and EF. Once several molecules of LF and EF have latched onto PA, the cell membrane tries to destroy these unwanted hangers-on by wrapping them up in an "endosome," a small bubble of membrane that gets pinched off and moved into the cell's interior. There, the cell attempts to destroy its contents by a process that includes making the interior of the endosome more acidic. But before the cell can fully carry out its plan, the LF and EF escape from the endosome and wreak havoc in the cell's interior. The question is: how do these toxins escape? "A recent hypothesis is that LF and EF completely unfold and then squeeze through the narrow hole that PA forms in the endosomal membrane," says NIST physical scientist Dr. John Kasianowicz.