Genetic variant linked to odor perceptionSeptember 17, 2007DURHAM, N.C. - Why the same sweaty man smells pleasant to one person and repellant to another comes down to the smeller's genes. Duke University Medical Center researchers demonstrated that genetic variants of odor receptors within the nose determine how a particular odor is perceived. The researchers, led by Duke's Hiroaki Matsunami, Ph.D., assistant professor of molecular genetics and microbiology, published the results of their experiments early online Sept. 16 in the journal Nature. The researchers focused on two chemicals - androstenone and androstadienone - that are created naturally by the body during the breakdown of the male sex hormone testosterone and are excreted in sweat and urine.
"We found that genetic variations of a specific odor receptor determine, to a significant degree, why the same chemicals smell pleasant or unpleasant to different people," Matsunami said. "These results demonstrate the first link between the functioning of a human odor receptor gene and how that odor is perceived." Humans have about 400 odor receptors within the nose that detect various odors or chemicals. Smells typically bind to their corresponding receptors, and the information is then relayed to the brain for processing. The researchers wanted to uncover the reasons why people react differently when they smell these two sex steroid-derived chemicals. Hanyi Zhuang, a student in the Matsunami laboratory, tested all the known smell receptors in the laboratory and found one that reacted strongly with the two chemicals. In conjunction with their collaborators at Rockefeller University, the researchers asked 391 volunteers to inhale the two chemicals and describe what they smelled. The results ranged from no smell at all, to descriptions such as "vanilla and sweet" and "sickening and urine." DNA extracted from blood samples from each volunteer were sent to Matsunami's laboratory. "After performing genetic analysis on each of the samples and correlating the results with the smell descriptions, we were able to link specific genetic variants with specific perceptions," Matsunami said. "While many theories of the different perceptions of smell focus on culture, experience or memory, our results show that an important portion of this variability is due to an individual's genes." Matsunami added that these results will likely add to the debate over the existence of pheromones in humans. Pheromones are chemical signals between animals that express alarm, mating and navigation cues. In other species, they've been found to trigger behavioral changes in the smeller. "The sex-steroid odors that we tested in humans act as pheromones in pigs, and there has been debate whether these same chemicals act similarly in humans," Matsunami said. "There is evidence that smelling these odors can affect the mood and physiological state of both men and women." Matsunami and his colleagues plan further studies to understand how smelling these chemicals might affect human social and sexual behavior. He added that there are likely other receptors and receptor variants that may also play roles in how these two chemicals are perceived. Since it is known that there are about 400 specific smell receptors and humans can detect more than 10,000 different odors, it follows that different combinations of receptor genes and variants must be involved in perceiving each odor, he said. Duke University Medical Center | |||||||||||||||||||||
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Related Odor Current Events and Odor News Articles Bound by Attention: Bringing rats and humans together When picking through a basket of fruit, it doesn't seem very difficult to recognize a green pear from a green apple. This is easy, thanks to "feature binding"- a process by which our brain combines all of the specific features of an object and gives us a complete and unified picture of it. Smokers see decline in ability to smell, rise in laryngitis, and upper airway issues As Americans prepare for a day without cigarettes and tobacco products as part of the American Cancer Society Great American Smokeout (R) (November 20), new research gives them more reasons to extend that break to a lifetime. Sniffing out a better chemical sensor Marrying a sensitive detector technology capable of distinguishing hundreds of different chemical compounds with a pattern-recognition module that mimics the way animals recognize odors, researchers at the National Institute of Standards and Technology (NIST) have created a new approach for "electronic noses." Emotion and scent create lasting memories -- even in a sleeping brain When French memoirist Marcel Proust dipped a pastry into his tea, the distinctive scent it produced suddenly opened the flood gates of his memory. Moths with a nose for learning Much like Pavlov conditioned his dog to salivate in anticipation of food when a bell rang, insects can be trained to perform certain behaviors when enticed with different smells. MIT paves way to 'artificial nose' MIT biological engineers have found a way to mass-produce smell receptors in the laboratory, an advance that paves the way for "artificial noses" to be created and used in a variety of settings. Mate selection more biologically determined in some human populations Some human populations may rely on biological factors in addition to social factors when selecting a mate. In a recent study, published September 12 in the open-access journal PLoS Genetics, scientists in China, France, and the United Kingdom report genomic data showing that immunity traits may be involved in mate choice in some human populations. National guidelines released for earwax removal The American Academy of Otolaryngology - Head and Neck Surgery Foundation (AAO-HNSF) will issue the first comprehensive clinical guidelines to help health care practitioners identify patients with cerumen (commonly referred to as earwax) impaction. The guidelines emphasize evidence-based management of cerumen impaction by clinicians, and inform patients of the purpose of ear wax in hearing health. Researchers discover scent of skin cancer According to new research from the Monell Center, odors from skin can be used to identify basal cell carcinoma, the most common form of skin cancer. The findings, presented at the 236th meeting of the American Chemical Society, may open doors to development of new methods to detect basal cell carcinoma and other forms of skin cancer. New 52-city report examines use of wastewater in urban agriculture As developing countries confront the first global food crisis since the 1970s as well as unprecedented water scarcity, a new 53-city survey conducted by the International Water Management Institute (IWMI) indicates that most of those studied (80 percent) are using untreated or partially treated wastewater for agriculture. In over 70 percent of the cities studied, more than half of urban agricultural land is irrigated with wastewater that is either raw or diluted in streams. More Odor Current Events and Odor News Articles |
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