Links for Keyword: Chemical Senses (Smell & Taste)

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By Caitlin Kirkwood Do NOT EAT the chemicals. It is the #1 laboratory safety rule young scientists learn to never break and for good reason; it keeps lab citizens alive and unscathed. However, if it hadn’t been for the careless, rule-breaking habits of a few rowdy scientists ingesting their experiments, many artificial sweeteners may never have been discovered. Perhaps the strangest anecdote for artificial sweetener discovery, among tales of inadvertent finger-licking and smoking, is that of graduate student Shashikant Phadnis who misheard instructions from his advisor to ‘test’ a compound and instead tasted it. Rather than keeling over, he identified the sweet taste of sucralose, the artificial sweetener commonly known today as Splenda. Artificial sweeteners like Splenda, Sweet’N Low, and Equal provide a sweet taste without the calories. Around World War II, in response to a sugar shortage and evolving cultural views of beauty, the target consumer group for noncaloric sweetener manufacturers shifted from primarily diabetics to anyone in the general public wishing to reduce sugar intake and lose weight. Foods containing artificial sweeteners changed their labels. Instead of cautioning ‘only for consumption by those who must restrict sugar intake’, they read for those who ‘desire to restrict’ sugar. Today, the country is in the middle of a massive debate about the health implications of artificial sweeteners and whether they could be linked to obesity, cancer, and Alzheimer disease. It’s a good conversation to have because noncaloric sweeteners are consumed regularly in chewing gums, frozen dinners, yogurts, vitamins, baby food, and particularly in diet sodas. © 2013 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 18614 - Posted: 09.07.2013

Josh Howgego When it comes to our sense of smell, we are all experiencing the world in very different ways. Scientists already know that humans' sensitivity to smelly molecules varies considerably from person to person (see: 'Soapy taste of coriander linked to genetic variants'). But evidence that genetic variations — as opposed to habit, culture or other factors — underlie these differences has been hard to come by. Geneticist Richard Newcomb of the New Zealand institute for Plant and Food Research in Auckland and his colleagues searched for olfactory genes by testing 187 people’s sensitivity to ten chemicals found in everyday food, including the molecules that give distinctive smells to blue cheese, apples and violets. They found that, as expected, the smelling abilities of their subjects varied. The team then sequenced the subjects’ genomes and looked for differences that could predict people’s ability to detect each chemical through smell. For four of the ten chemicals, the researchers identified clusters of genes that convincingly predicted smelling ability, as they report today in Current Biology1. The study could not conclude whether similar genetic associations exist for the other six compounds, or whether factors other than genes play a role in those cases. Previously, only five regions of the genome had been shown to affect olfactory ability when they undergo mutations, so Newcomb’s study has nearly doubled the number of genetic associations known to influence smell. And because there is nothing special about the chemicals they studied, Newcomb says that it is logical to think the findings would extend to lots of scents, meaning that people experience the plethora of chemicals surrounding them in endlessly different ways. © 2013 Nature Publishing Group

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 18454 - Posted: 08.03.2013

By Scicurious Sometimes, funny stories really bring out the wonder of the human body. You can get orgasms triggered in your feet, because of overlap in the sensory cortex. Receptors that are involved in narcolepsy are also involved in how much you eat. And knocking out receptors that regulate taste…can make you sterile? Who knew? Let’s start with taste. We taste because the chemicals in foods hit receptors on our tongues. Receptors for sweet, salt, bitter, sour, and umami (which can commonly be thought of as “savory”). Now, a receptor isn’t just a single protein, it’s actually several protein subunits working together to function. So, for example, the receptor subunit TAS1R3 is a subunit that can play two different tasting roles. When combined with one other subunit, it helps to sense sweet (like saccharin), and when combined with another, if helps you taste umami (like MSG, which is definitely umami flavored). If you get rid of the gene for TAS1R3, you end up with an animal that can’t detect either sweet or umami very well. There’s another subunit that is covered in this paper as well, GNAT3. GNAT3, instead of being specific for something like sweet or bitter, instead plays a role in “basic taste“. But these two protein subunits are not JUST expressed on the tongue and in the gastrointestinal tract. They are expressed elsewhere in the body…and especially in the testicles. © 2013 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 18336 - Posted: 07.02.2013

David Derbyshire Every year Robert Hodgson selects the finest wines from his small California winery and puts them into competitions around the state. And in most years, the results are surprisingly inconsistent: some whites rated as gold medallists in one contest do badly in another. Reds adored by some panels are dismissed by others. Over the decades Hodgson, a softly spoken retired oceanographer, became curious. Judging wines is by its nature subjective, but the awards appeared to be handed out at random. So drawing on his background in statistics, Hodgson approached the organisers of the California State Fair wine competition, the oldest contest of its kind in North America, and proposed an experiment for their annual June tasting sessions. Each panel of four judges would be presented with their usual "flight" of samples to sniff, sip and slurp. But some wines would be presented to the panel three times, poured from the same bottle each time. The results would be compiled and analysed to see whether wine testing really is scientific. The first experiment took place in 2005. The last was in Sacramento earlier this month. Hodgson's findings have stunned the wine industry. Over the years he has shown again and again that even trained, professional palates are terrible at judging wine. "The results are disturbing," says Hodgson from the Fieldbrook Winery in Humboldt County, described by its owner as a rural paradise. "Only about 10% of judges are consistent and those judges who were consistent one year were ordinary the next year. © 2013 Guardian News and Media Limited

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 14: Attention and Consciousness
Link ID: 18319 - Posted: 06.29.2013

By Helen Briggs BBC News Our perception of how food tastes is influenced by cutlery, research suggests. Size, weight, shape and colour all have an effect on flavour, says a University of Oxford team. Cheese tastes saltier when eaten from a knife rather than a fork; while white spoons make yoghurt taste better, experiments show. The study in the journal Flavour suggests the brain makes judgements on food even before it goes in the mouth. More than 100 students took part in three experiments looking at the influence of weight, colour and shape of cutlery on taste. The researchers found that when the weight of the cutlery confirms to expectations, this had an impact on how the food tastes. For example, food tasted sweeter on the small spoons that are traditionally used to serve desserts. Colour contrast was also an important factor - white yoghurt eaten from a white spoon was rated sweeter than white yoghurt tasted on a black spoon. Similarly, when testers were offered cheese on a knife, spoon, fork or toothpick, they found that the cheese from a knife tasted saltiest. "How we experience food is a multisensory experience involving taste, feel of the food in our mouths, aroma, and the feasting of our eyes," said Prof Charles Spence and Dr Vanessa Harrar. BBC © 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 18315 - Posted: 06.26.2013

by Paul Gabrielsen Take a whiff, men. A chemical component of other guys' sweat makes men more cooperative and generous, new research says. The study is the first to show that this pheromone, called androstadienone, influences other men's behavior and reinforces the developing finding that humans are susceptible and responsive to these chemical signals. Pheromones are everywhere in the animal world. Bugs in particular give off these chemicals to sound an alarm, identify a food source, or attract a mate. And smitten animals may indeed have "chemistry" together—pheromone signals are a subconscious part of their communication. Scientists didn't know if humans played that game as well. But in the last 30 years, they've identified both male and female putative pheromones that are linked to mood and reproductive cycles. Some fragrancemakers have even incorporated them into their products, hoping to add an extra emotional punch to colognes and perfumes. Real-life pheromones don't smell so nice, however: The specialized glands that produce these chemical compounds are located near the armpit, where they mix with sweat. Previous investigations focused on the chemicals as sexual attractants—studying a male pheromone's effect on female mood and behavior, for example. Turns out that women aren't the only ones susceptible to the power of male pheromones. Evolutionary biologist Markus Rantala of the University of Turku in Finland crafted an experiment in which 40 men in their mid-20s played a computer game in which two players decided how to share €10. One player offers a possible split, and the other decides whether to accept or reject it. Each participant took a turn making or deciding on offers. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 18217 - Posted: 06.01.2013

By Susan Milius Cockroaches that don’t fall for traps’ sweet poisons have evolved taste cells that register sugar as bitter. In certain groups of the widespread German cockroach (Blattella germanica), nerve cells that normally detect bitter, potentially toxic compounds now also respond to glucose, says entomologist Coby Schal of North Carolina State University in Raleigh. The “bitter” reaction suppresses the “sweet” response from other nerve cells, and the roach stops eating, Schal and his colleagues report in the May 24 Science. Normally roaches love sugar. But with these populations, a dab of jelly with glucose in it makes them “jump back,” Schal says. “The response is: ‘Yuck! Terrible!’” This quirk of roach taste explains why glucose-baited poison traps stopped working among certain roaches, Schal says. Such bait traps combining a pesticide with something delicious became popular during the mid-1980s. But in 1993, Jules Silverman, also a coauthor on the new paper, reported roaches avoiding these once-appealing baits. “This is a fascinating piece of work because it shows how quickly, and how simply, the sense of taste can evolve,” says neurobiologist Richard Benton of the University of Lausanne in Switzerland. What pest-control manufacturers put in their roach baits now, and whether some still use glucose, isn’t public, Schal says. But humankind’s arms race with cockroaches could have started long ago, “in the caves,” he says. In this back-and-forth struggle, it’s important “to understand what the cockroach is doing from a molecular basis.” © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 18193 - Posted: 05.25.2013

by Meera Senthilingam Malaria parasites give mosquitoes a keener sense of smell, it seems. A small-scale study in the lab finds that mosquitoes infected by the parasite are three times as likely as uninfected mosquitoes to respond to human odours. If the same results are seen in malaria-carrying mosquitoes in the wild, it could lead to new ways to combat the disease. Female anopheles mosquitoes are attracted to the chemicals in human odours, which help them find the source of blood they need to grow their eggs. When these mosquitoes carry Plasmodium falciparum – the most lethal form of malaria parasite – the likelihood that they will target humans rises. "We knew already that mosquitoes bite more often when they're infected. They probe the skin more frequently," says James Logan from the London School of Hygiene and Tropical Medicine. To quantify the effect – and try to work out its cause – Logan and his colleagues infected some lab-grown Anopheles gambiae mosquitoes with Plasmodium parasites, while leaving others uninfected. They then tested how both groups were attracted to human smells. Mosquitoes are particularly attracted to foot odours, so Logan's team used nylon stockings containing the volatile chemicals produced by our feet. Over a period of three minutes, Plasmodium-infected mosquitoes landed and attempted to bite the stockings around 15 times on average. By contrast, the uninfected mosquitoes attempted to bite only around five times on average during that time. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 18160 - Posted: 05.16.2013

Published by scicurious I love salt. It's just delicious. I wrote this post while noshing on deliciously salty popcorn, after a dinner which I put salt on. I crave salt so much that my parents used to joke about getting me a salt lick. And I'm not alone. Sodium is an incredibly important part of life, which means it's also an important part of what we eat. To make sure we get enough salt, animals have evolved salt-sensing systems, and low levels (below 100 mM of NaCl) of salt are very attractive. But there IS such a thing as too much salt. High levels of salt (>300 mM NaCl) are really aversive (from personal experience, I wonder if Carrabba's restaurant has concentrations of salt in their food over 300 mM). Most animals will quickly turn up their noses at a high salt concentration. You probably know that you have classes of receptors on your tongue for taste (though they are not clustered into areas of your mouth, like front for sweetness, as previously thought). You have sweet, umami (savory), bitter, sour, and salt. In most animals, sweet and umami are always attractive, while bitter and sour are nasty (except where we have overcome the aversion to enjoy things like coffee and beer). Salt, though, is the only one that goes two ways, with low levels being attractive and high levels being aversive. Now we know how low salt works. The salt receptors that are currently known are good for detecting low salt. But high salt, that's more difficult. First of all, our aversion to high salt concentrations is not very selective. While low salt detection is limited to good old NaCl, high salt detection is non-specific, working for many salts including NaCl, but others as well (like KCl). Neurotic Physiology Copyright © 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 18025 - Posted: 04.13.2013

Published by scicurious Today's post comes to you courtesy of Mary Roach (aka, the person I want to be when I grow up). I have a copy of her latest book, Gulp: adventures in the alimentary canal that I am reading for review, and a weird science connoisseur such as myself of course spends half her time in the bibliography section, wherein I located this paper. This paper may thus be taken as a pre-review of the book. Spoiler: so far, the book is FABULOUS, but should never be read while eating. Ah, goat milk. When I think of goat milk, I think of places like farmer's markets, Whole Foods, and little Heidi dancing through the alps. I'll admit to never having drunk raw goat milk (though I do LOVE goat cheese). But after having read this paper, I'm afraid that I do not WANT to try raw goat milk. Why? I'm afraid of the taste...the goaty taste...that is potentially hot, sexy goaty hormones. Hot sexy goat hormones sprayed around in hot, sexy goaty URINE. So, goat milk doesn't usually taste...well, goaty. Usually it tastes pretty much like cow milk (whole fat cow milk, that is). But sometimes, you'll get a bad batch. Nothing's WRONG with it, per se, it's still healthy and not bad, but it's...goaty. The flavor and smell are musky and weird, and not at all tasty. So obviously you want to find the source of that problem. For years, people who raise goats have pinpointed the MALE goat as the source of the issue. Male goats smell very goaty indeed, particularly during the goat mating season (the rutting season). Some of the odors they emit are so strong they can be smelled several hundred meters away. The odors are very volatile, so they will spread easily, and the idea has long been that if your male goat is around the ladies, his manly odors will get on them and in them, and thus in their milk, resulting in goaty milk (which, if the male goat is the cause, means that goaty milk is really just...MANLY). So goat farmers usually keep their male goats at a good distance from the females during the rutting season, to keep the males from getting their...manliness in the milk. Manliness is just not very tasty. Copyright © 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 17969 - Posted: 03.30.2013

by Hal Hodson THAT fried chicken advert is about to get even more tempting. Soon it might be pumping out the mouth-watering smell of the stuff too. Tough luck if you're a veggie. The "smelling screen", invented by Haruka Matsukura at Tokyo University of Agriculture and Technology in Japan and colleagues, makes smells appear to come from the exact spot on any LCD screen that is displaying the image of a cup of coffee, for example. It works by continuously feeding odours from vaporising gel pellets into four air streams, one in each corner of the screen. These air streams are blown out parallel to the screen's surface by fans, and varying the strength and direction of them manoeuvres the scent to any given spot on the screen. The airflow is gentle enough that the team have been able to create the illusion that the smell is actually wafting from a digital object on-screen. The current system only pumps out one scent at a time, but Matsukura says the next stage is to incorporate a cartridge, like those for printers, which allows smells to be changed easily. The screen was shown at the IEEE Virtual Reality conference in Orlando, Florida, last week. Matsukura suggests it could also be used to enhance advertising screensMovie Camera and museum exhibits. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17967 - Posted: 03.30.2013

By MARY ROACH WAGENINGEN, THE NETHERLANDS — When I told people I was traveling to Food Valley, I described it as the Silicon Valley of eating. At this cluster of universities and research facilities, nearly 15,000 scientists are dedicated to improving — or, depending on your sentiments about processed food, compromising — the quality of our meals. At the time I made the Silicon Valley comparison, I did not expect to be served actual silicone. But here I am, in the Restaurant of the Future, a cafeteria at Wageningen University where hidden cameras record diners as they make decisions about what to eat. And here it is, a bowl of rubbery white cubes the size of salad croutons. Andries van der Bilt has brought them from his lab in the brusquely named Department of Head and Neck, at the nearby University Medical Center Utrecht. “You chew them,” he said. The cubes are made of a trademarked product called Comfort Putty, more typically used in its unhardened form for taking dental impressions. Dr. Van der Bilt isn’t a dentist, however. He is an oral physiologist, and he likely knows more about chewing than anyone else in the world. He uses the cubes to quantify “masticatory performance” — how effectively a person chews. I take a cube from the bowl. If you ever, as a child, chewed on a whimsical pencil eraser in the shape of, say, an animal or a piece of fruit, then you have tasted this dish. “I’m sorry.” Dr. Van der Bilt winces. “It’s quite old.” As though fresh silicone might be better. © 2013 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 5: The Sensorimotor System
Link ID: 17949 - Posted: 03.26.2013

by Audrey Carlsen Plenty of us got our fill of green-colored food on St. Patrick's Day. (Green beer, anyone?) But for some people, associating taste with color is more than just a once-a-year experience. These people have synesthesia — a neurological condition in which stimulation of one sense (e.g., taste) produces experiences in a totally different sense (e.g., sight). According to researcher Sean Day, approximately one in 27 people has some form of synesthesia. We've covered this phenomenon in the past. And I'm a synesthete myself — I see letters and numbers in color, and associate sounds with shapes and textures. But only a very few people — maybe only 1 percent of synesthetes — have sensory crossovers that affect their relationship with food and drink. Jaime Smith is one of those people. He's a sommelier by trade, and he has a rare gift: He smells in colors and shapes. For Smith, who lives in Las Vegas, a white wine like Nosiola has a "beautiful aquamarine, flowy, kind of wavy color to it." Other smells also elicit three-dimensional textures and colors on what he describes as a "projector" in his mind's eye. This "added dimension," Smith says, enhances his ability to appraise and analyze wines. "I feel that I have an advantage over a lot of people, particularly in a field where you're judged on how good of a smeller you are," he says. ©2013 NPR

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 14: Attention and Consciousness
Link ID: 17915 - Posted: 03.19.2013

By SINDYA N. BHANOO Humans and many other mammals see and hear in stereo. But what about smell? “People have wondered for a long time whether smell has this component as well,” said Kenneth C. Catania, a biologist at Vanderbilt University. Now he and colleagues report in the journal Nature Communications that common moles, which are blind, have the ability and use it to swiftly locate prey. Dr. Catania created a chamber with food wells spaced around a semicircle and watched as moles detected the food. The chamber was sealed, so changes in air pressure would indicate that the animals were sniffing. Moving their noses back and forth, the moles zeroed in on the food in less than five seconds. Dr. Catania then blocked one of the moles’ nostrils with a plastic tube. When the left nostril was blocked, the moles veered off to the right, and when the right was blocked, they veered to left. Although they were still able to find the food, it took them much longer. To confirm that the moles use stereo sniffing, Dr. Catania put plastic tubes in both nostrils and then crossed them. This confused the moles, causing them to think that food to their right was actually located to their left. But their response confirmed that the moles in fact use stereo sniffing, Dr. Catania said. Previous research indicates that rats can smell in stereo, and there are suggestions that sharks and ants can, too. “The jury is still out on how many animals can do this, and that will tell us how primitive this is,” Dr. Catania said. “If only a few animals do it, then it may have evolved recently.” So can humans smell in stereo? Unlikely, he said. © 2013 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17821 - Posted: 02.19.2013

by Hal Hodson CAN YOU imagine feeling Earth's magnetic field on the tip of your tongue? Strangely, this is now possible, using a device that converts the tongue into a "display" for output from environmental sensors. Gershon Dublon of the Massachusetts Institute of Technology devised a small pad containing electrodes in a 5 × 5 grid. Users put the pad, which Gershon calls Tongueduino, on their tongue. When hooked up to an electronic sensor, the pad converts signals from the sensor into small pulses of electric current across the grid, which the tongue "reads" as a pattern of tingles. Dublon says the brain quickly adapts to new stimuli on the tongue and integrates them into our senses. For example, if Tongueduino is attached to a sensor that detects Earth's magnetic field, users can learn to use their tongue as a compass. "You might not have to train much," he says. "You could just put this on and start to perceive." Dublon has been testing Tongueduino on himself for the past year using a range of environmental sensors. He will now try the device out on 12 volunteers. Blair MacIntyre at the Georgia Institute of Technology in Atlanta says a wireless version of Tongueduino could prove useful in augmented reality applications that deliver information to users inconspicuously, without interfering with their vision or hearing. "There's a need for forms of awareness that aren't socially intrusive," he says. Even Google's much-publicised Project Glass will involve wearing a headset, he points out. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17806 - Posted: 02.16.2013

by Lizzie Wade When a male wasp decides it's time to settle down and start a family, he releases a chemical calling card in the form of pheromones, broadcasting his location, his availability, and, most importantly, his identity. Most other kinds of insects will either ignore his signal or be repelled by it, but female wasps of his own species will buzz over and get down to business. But how and why did different pheromone blends—and the species that prefer them—evolve in the first place? A new study offers a possible solution to this long-standing evolutionary mystery, suggesting that new sex pheromones may evolve through genetic mutation before potential mates develop the ability to detect them. Scientists have long been impressed by the perfect harmony of chemical communication among insects, especially when it comes to choosing mates by detecting and responding to the sex pheromones of only their own species. But scientists were puzzled by how such a delicate system evolved. If female wasps respond to only a specific blend of pheromones, males that produce even a subtly different blend shouldn't have much luck mating and passing on their mutant genes. It seemed that in order for males to evolve new pheromones, the female insects would need some preexisting adaptation that would cause them to prefer the new chemical blend. But how could they evolve a preference for something they had never encountered and should, logic suggests, find off-putting? In essence, the question is which came first, a new species or its sex pheromone? In order to answer this question, a team of researchers in Germany turned to the Nasonia vitripennis wasp, a species famous for its propensity to lay its parasitic eggs on doomed fly pupae. When the scientists analyzed the N. vitripennis male sex pheromone, they found it contained two important chemicals, which they call RS and RR. RS also turns up in the male sex pheromones of another species of wasp, N. giraulti, whereas RR appears to be unique. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17803 - Posted: 02.14.2013

By Tina Hesman Saey The common mole may be homely but its nose is a wonder to behold. The eastern American mole, also known as the common mole, tracks down an earthworm treat by recognizing the slightly different odor cues entering each nostril, neurobiologist Kenneth Catania of Vanderbilt University in Nashville reports online February 5 in Nature Communications. The finding suggests that even though mole nostrils are separated by a fraction of a centimeter, each gets its own scent information that can guide an animal’s actions. “It’s an elegant demonstration of what many people suspected,” says Peter Brunjes, a neuroscientist at the University of Virginia. Previous experiments with people and rats had reached contradictory conclusions regarding whether smell, like sight and hearing, is a bilateral sense. Catania never expected the common mole, Scalopus aquaticus, to have uncommon abilities. “I’ve described it as the unlucky, stupid cousin of the star-nosed mole,” he says. Star-nosed moles, Condylura cristata, have an incredible sense of touch in their tentacled schnozzes and are among the world’s fastest foragers. But compared with other mole species, the eastern American mole has a poor sense of touch. The animals also can’t see. Catania turned to common moles because he thought they would have a hard time finding food and could be tested against star-nosed moles in future experiments. But when he placed a common mole in a semicircular arena with a chopped up bit of earthworm as bait, he says, “it would wiggle its nose around and go in a beeline toward the food.” © Society for Science & the Public 2000 - 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17768 - Posted: 02.06.2013

by Elizabeth Pennisi Though often associated with dirty environments, cockroaches are actually quite fastidious, especially when it comes to their antennae. They clean them often by grabbing one in with a front leg and drawing it through their mouth. Researchers have long observed that many insects groom themselves, and now they know why. When scientists restrained American cockroaches or prevented grooming by gluing mouthparts for 24 hours, they noticed a shiny, waxy buildup on the antennae that clogs the tiny pores that lead to odor-sensing cells. Measurements of the electrical activity in those cells in response to sex-attractant and food odors showed that the gunk interfered with the roach's sense of smell, they report online today in the Proceedings of the National Academy of Sciences. The insects appear to produce wax continuously, likely to keep from drying out, and grooming helps remove the excess as well as dust and other foreign chemicals that land on the antennae and get trapped in the gunk. Carpenter ants, houseflies, and German cockroaches also suffered from gunk overload when prohibited from grooming, suggesting that fastidiousness is widespread. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17755 - Posted: 02.05.2013

By Jason Palmer Science and technology reporter, BBC News A controversial theory that the way we smell involves a quantum physics effect has received a boost, following experiments with human subjects. It challenges the notion that our sense of smell depends only on the shapes of molecules we sniff in the air. Instead, it suggests that the molecules' vibrations are responsible. A way to test it is with two molecules of the same shape, but with different vibrations. A report in PLOS ONE shows that humans can distinguish the two. Tantalisingly, the idea hints at quantum effects occurring in biological systems - an idea that is itself driving a new field of science, as the BBC feature article Are birds hijacking quantum physics? points out. But the theory - first put forward by Luca Turin, now of the Fleming Biomedical Research Sciences Centre in Greece - remains contested and divisive. The idea that molecules' shapes are the only link to their smell is well entrenched, but Dr Turin said there were holes in the idea. He gave the example of molecules that include sulphur and hydrogen atoms bonded together - they may take a wide range of shapes, but all of them smell of rotten eggs. "If you look from the [traditional] standpoint... it's really hard to explain," Dr Turin told BBC News. "If you look from the standpoint of an alternative theory - that what determines the smell of a molecule is the vibrations - the sulphur-hydrogen mystery becomes absolutely clear." BBC © 2013

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17724 - Posted: 01.28.2013

by Sarah C. P. Williams You might not be able to pick your fingerprint out of an inky lineup, but your brain knows what you smell like. For the first time, scientists have shown that people recognize their own scent based on their particular combination of major histocompatibility complex (MHC) proteins, molecules similar to those used by animals to choose their mates. The discovery suggests that humans can also exploit the molecules to differentiate between people. "This is definitely new and exciting," says Frank Zufall, a neurobiologist at Saarland University's School of Medicine in Homburg, Germany, who was not involved in the work. "This type of experiment had never been done on humans before." MHC peptides are found on the surface of almost all cells in the human body, helping inform the immune system that the cells are ours. Because a given combination of MHC peptides—called an MHC type—is unique to a person, they can help the body recognize invading pathogens and foreign cells. Over the past 2 decades, scientists have discovered that the molecules also foster communication between animals, including mice and fish. Stickleback fish, for example, choose mates with different MHC types than their own. Then, in 1995, researchers conducted the now famous "sweaty T-shirt study," which concluded that women prefer the smell of men who have different MHC genes than themselves. But no studies had shown a clear-cut physiological response to MHC proteins. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17716 - Posted: 01.26.2013