By Ian Randall It’s one of life’s little ironies: Sweet foods get sweeter when you add a little salt. Now, scientists may have provided connoisseurs of salted caramel and grapefruit with the reason this culinary trick is worth its salt. Your ability to savor food comes from the receptor cells in your tongue’s taste buds. Sweet tastes are detected by a family of receptors called T1R, which pick up both natural sugars and artificial sweeteners. Scientists originally thought disabling the T1R family would stop any responses to sweet stimuli. But in 2003, researchers showed that mice whose T1R genes had been genetically “knocked out” still liked the sugar glucose. The finding suggested there must be another way that mice—and possibly humans—sense sweetness. Seeking an explanation, physiologist Keiko Yasumatsu of Tokyo Dental Junior College and colleagues turned to a protein that works with glucose elsewhere in the body: sodium-glucose cotransporter 1 (SGLT1). In the kidneys and intestine, SGLT1 uses sodium to carry glucose into cells to provide them with energy. Curiously, the protein is also found in sweet-responsive taste cells. The researchers rubbed the tongues of unconscious T1R mice with a solution of glucose and salt—which contains the sodium SGLT1 needs to work—and recorded the responses of nerves connected to their taste cells. The salt seemed to make all the difference: It caused the rodents’ nerves to fire more rapidly, compared with mutated mice given only glucose. Conscious mice also seemed to show a preference for the sugar-salt solution. But this only worked with glucose; sweeteners like saccharin didn’t trigger a response. © 2020 American Association for the Advancement of Science.

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27510 - Posted: 10.07.2020

Jon Henley Europe correspondent Four Covid-19 sniffer dogs have begun work at Helsinki airport in a state-funded pilot scheme that Finnish researchers hope will provide a cheap, fast and effective alternative method of testing people for the virus. A dog is capable of detecting the presence of the coronavirus within 10 seconds and the entire process takes less than a minute to complete, according to Anna Hielm-Björkman of the University of Helsinki, who is overseeing the trial. “It’s very promising,” said Hielm-Björkman. “If it works, it could prove a good screening method in other places” such as hospitals, care homes and at sporting and cultural events. After collecting their luggage, arriving international passengers are asked to dab their skin with a wipe. In a separate booth, the beaker containing the wipe is then placed next to others containing different control scents – and the dog starts sniffing. If it indicates it has detected the virus – usually by yelping, pawing or lying down – the passenger is advised to take a free standard polymerase chain reaction (PCR) test, using a nasal swab, to verify the dog’s verdict. In the university’s preliminary tests, dogs – which have been successfully used to detect diseases such as cancer and diabetes – were able to identify the virus with nearly 100% accuracy, even days before before a patient developed symptoms. Scientists are not yet sure what exactly it is that the dogs sniff when they detect the virus. A French study published in June concluded that there was “very high evidence” that the sweat odour of Covid-positive people was different to that of those who did not have the virus, and that dogs could detect that difference. Dogs are also able to identify Covid-19 from a much smaller molecular sample than PCR tests, Helsinki airport said, needing only 10-100 molecules to detect the presence of the virus compared with the 18m needed by laboratory equipment. © 2020 Guardian News & Media Limited

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27490 - Posted: 09.25.2020

By Carolyn Wilke Taste buds can turn food from mere fuel into a memorable meal. Now researchers have discovered a set of supersensing cells in the taste buds of mice that can detect four of the five flavors that the buds recognize. Bitter, sweet, sour and umami — these cells can catch them all. That’s a surprise because it’s commonly thought that taste cells are very specific, detecting just one or two flavors. Some known taste cells respond to only one compound, for instance, detecting sweet sucralose or bitter caffeine. But the new results suggest that a far more complicated process is at work. When neurophysiologist Debarghya Dutta Banik and colleagues turned off the sensing abilities of more specific taste cells in mice, the researchers were startled to find other cells responding to flavors. Pulling those cells out of the rodents’ taste buds and giving them a taste of several compounds revealed a group of cells that can sense multiple chemicals across different taste classes, the team reports August 13 in PLOS Genetics. “We never expected that any population of [taste] cells would respond to so many different compounds,” says Dutta Banik, of the Indiana University School of Medicine in Indianapolis. But taste cells don’t respond to flavors in insolation; the brain and the tongue work together as tastemakers (SN: 11/24/15). So the scientists monitored the brain to see if it received bitter, sweet or umami signals when mice lacked a key protein needed for these broadly tasting cells to relay information. Those observations revealed that without the protein, the brain didn’t get the flavor messages, which was also shown when mice slurped bitter solutions as though they were water even though the rodents hate bitter tastes, says Dutta Banik, who did the work at the University at Buffalo in New York. © Society for Science & the Public 2000–2020.

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27419 - Posted: 08.15.2020

Ian Sample Science editor Scientists have unravelled the mysterious mechanism behind the armpit’s ability to produce the pungent smell of body odour. Researchers at the University of York traced the source of underarm odour to a particular enzyme in a certain microbe that lives in the human armpit. To prove the enzyme was the chemical culprit, the scientists transferred it to an innocent member of the underarm microbe community and noted – to their delight – that it too began to emanate bad smells. The work paves the way for more effective deodorants and antiperspirants, the scientists believe, and suggests that humans may have inherited the mephitic microbes from our ancient primate ancestors. “We’ve discovered how the odour is produced,” said Prof Gavin Thomas, a senior microbiologist on the team. “What we really want to understand now is why.” Humans do not produce the most pungent constituents of BO directly. The offending odours, known as thioalcohols, are released as a byproduct when microbes feast on other compounds they encounter on the skin. The York team previously discovered that most microbes on the skin cannot make thioalcohols. But further tests revealed that one armpit-dwelling species, Staphylococcus hominis, was a major contributor. The bacteria produce the fetid fumes when they consume an odourless compound called Cys-Gly-3M3SH, which is released by sweat glands in the armpit. Advertisement Humans come with two types of sweat glands. Eccrine glands cover the body and open directly onto the skin. They are an essential component of the body’s cooling system. Apocrine glands, on the other hand, open into hair follicles, and are crammed into particular places: the armpits, nipples and genitals. Their role is not so clear. © 2020 Guardian News & Media Limited

Related chapters from BN: Chapter 9: Hearing, Balance, 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: 27390 - Posted: 07.29.2020

Edmund Chong When you experience something with your senses, it evokes complex patterns of activity in your brain. One important goal in neuroscience is to decipher how these neural patterns drive the sensory experience. For example, can the smell of chocolate be represented by a single brain cell, groups of cells firing all at the same time or cells firing in some precise symphony? The answers to these questions will lead to a broader understanding of how our brains represent the external world. They also have implications for treating disorders where the brain fails in representing the external world: for example, in the loss of sight of smell. To understand how the brain drives sensory experience, my colleagues and I focus on the sense of smell in mice. We directly control a mouse’s neural activity, generating “synthetic smells” in the olfactory part of its brain in order to learn more about how the sense of smell works. Our latest experiments discovered that scents are represented by very specific patterns of activity in the brain. Like the notes of a melody, the cells fire in a unique sequence with particular timing to represent the sensation of smelling a unique odor. Using mice to study smell is appealing to researchers because the relevant brain circuits have been mapped out, and modern tools allow us to directly manipulate these brain connections. © 2010–2020, The Conversation US, Inc.

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27352 - Posted: 07.08.2020

By Bret Stetka How do humans and other animals distinguish between the smell of rotting seafood or the enticing allure of a ripe banana? New research at New York University Langone Health and their colleagues uses artificially created odors to help reveal the intricate chain of events that allow one odor to be distinguished from another. The results were published today in Science. In the deep recesses of the nose are millions of sensory neurons that, along with our eyes and ears, help conjure the world around us. When stimulated by a chemical with a smell, or an odorant, they send nerve impulses to thousands of clusters of neurons in the glomeruli, which make up the olfactory bulb, the brain’s smell center. Different patterns of glomerular activation are known to generate the sensation of specific odors. Firing one set of glomeruli elicits the perception of pineapples; firing another evokes pickles. Unlike other sensations, such as sight and hearing, scientists do not know which qualities of a particular smell are used by the brain to perceive it. When you see a person’s face, you may remember the eyes, which helps you recognize that individual in the future. But the ears and nose might be less important in how the brain represents that person. The authors of the new study sought to identify distinguishing features involved in forming the representation of odors in the brain. To do so, they used a technique called optogenetics to activate glomeruli in mice. Optogenetics uses light to stimulate specific neurons in the brain. And it can help determine the function of particular brain regions. © 2020 Scientific American

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27315 - Posted: 06.22.2020

By Laura Sanders Scientists have implanted an artificial odor directly in the brains of mice. It doesn’t mean that mental Smell-O-Vision technology is coming soon. But the results, published June 18 in Science, deliver clues to how the brain processes information. Details about the synthetic smell may help answer “fundamental questions in olfaction,” says computational biologist Saket Navlakha of Cold Spring Harbor Laboratory in New York, who wasn’t involved in the study. Studies on the senses offer a window into how brains shape signals from the outside world into perceptions, and how those perceptions can guide behavior (SN: 7/18/19). To build artificial smells in mice’s brains, researchers used optogenetics, a technique in which light prods genetically engineered nerve cells to fire signals (SN: 1/15/10). Neuroscientist Dima Rinberg of New York University’s Grossman School of Medicine and colleagues targeted nerve cells in mice’s olfactory bulbs. There, clusters of nerve endings called glomeruli organize the smell signals picked up in the nose. Like playing a short ditty on a piano, Rinberg and colleagues activated nerve cells in six spots (each of which might include between one and three glomeruli) in a certain order. This neural melody was designed to be a simplified version of how a real odor might play those nerve cells. (It’s not known what the artificial odor actually smells like to a mouse.) © Society for Science & the Public 2000–2020.

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27312 - Posted: 06.19.2020

By Laura Sanders The virus responsible for COVID-19 can steal a person’s sense of smell, leaving them noseblind to fresh-cut grass, a pungent meal or even their own stale clothes. But so far, details remain elusive about how SARS-CoV-2, the coronavirus that causes COVID-19, can infiltrate and shut down the body’s smelling machinery. One recent hint comes from a young radiographer who lost her sense of smell. She had signs of viral infection in her brain. Other studies, though, have not turned up signs of the virus in the brain. Contradictory evidence means that no one knows whether SARS-CoV-2 can infect nerve cells in the brain directly, and if so, whether the virus’s route to the brain can sometimes start in the nose. Understanding how people’s sense of smell is harmed (SN: 5/11/20), a symptom estimated to afflict anywhere between 20 and 80 percent of people with COVID-19, could reveal more about how the virus operates. One thing is certain so far, though: The virus can steal the sense of smell in a way that’s not normal. “There’s something unusual about the relationship between COVID-19 and smell,” says neuroscientist Sandeep Robert Datta of Harvard Medical School in Boston. Colds can prevent smelling by stuffing the nose up with mucus. But SARS-CoV-2 generally leaves the nose clear. “Lots of people are complaining about losing their sense of smell when they don’t feel stuffed up at all,” Datta says. © Society for Science & the Public 2000–2020.

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27302 - Posted: 06.13.2020

­­Researchers at the National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of Health, have identified a specific, front-line defense that limits the infection to the olfactory bulb and protects the neurons of the olfactory bulb from damage due to the infection. Neurons in the nose respond to inhaled odors and send this information to a region of the brain referred to as the olfactory bulb. Although the location of nasal neurons and their exposure to the outside environment make them an easy target for infection by airborne viruses, viral respiratory infections rarely make their way from the olfactory bulb to the rest of the brain, where they could cause potentially fatal encephalitis. The study was published in Science Immunology. Taking advantage of special viruses that can be tracked with fluorescent microscopy, the researchers led by Dorian McGavern, Ph.D., senior investigator at NINDS, found that a viral infection that started in the nose was halted right before it could spread from the olfactory bulb to the rest of the central nervous system. “Airborne viruses challenge our immune system all the time, but rarely do we see viral infections leading to neurological conditions,” said Dr. McGavern. “This means that the immune system within this area has to be remarkably good at protecting the brain.” Additional experiments showed that microglia, immune cells within the central nervous system, took on an underappreciated role of helping the immune system recognize the virus and did so in a way that limited the damage to neurons themselves. This sparing of neurons is critical, because unlike cells in most other tissues, most neuronal populations do not come back.

Related chapters from BN: Chapter 15: Emotions, Aggression, and Stress; Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27287 - Posted: 06.06.2020

By Tina Hesman Saey A loss of smell and taste may be one of the clearest indicators of whether someone has COVID-19, a new study suggests. Researchers gleaned the information from nearly 2.5 million people in the United Kingdom and about 170,000 people in the United States who entered whether they were feeling well or experiencing symptoms into a smartphone app from March 24 to April 21. Some of the app users also reported results of PCR diagnostic tests for the SARS-CoV-2 virus, which causes COVID-19 (SN: 3/6/20). Nearly 65 percent of roughly 6,400 U.K. residents who tested positive for the virus described a loss of taste and smell as a symptom, researchers report May 11 in Nature Medicine. And just over 67 percent of the 726 U.S. participants with a positive test also reported losing those senses. Only about 20 percent of all people who tested negative had diminished smell and taste. Using data from the app, a team of scientists led by clinical researchers Claire Steves and Tim Spector, both of King’s College London, devised a formula for determining which symptoms best predict COVID-19. A combination of loss of taste and smell, extreme fatigue, cough and loss of appetite was the best predictor of having a positive result from the PCR test, the team found. Based on those symptoms, the researchers estimate that more than 140,000 of the more than 800,000 app users who reported symptoms probably have COVID-19. © Society for Science & the Public 2000–2020.

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27241 - Posted: 05.12.2020

By Michelle Roberts Health editor, BBC News online A loss of smell or taste may be a sign that you have coronavirus, according to UK researchers. A team at King's College London looked at responses from more than 400,000 people reporting suspected Covid-19 symptoms to an app. But loss of smell and taste are also signs of other respiratory infections, such as the common cold. And experts say fever and cough remain the most important symptoms of the virus to look out for and act upon. If you or someone you live with has a new continuous cough or high temperature, the advice is stay at home to stop the risk of spreading coronavirus to others. Coronavirus: What should I do? What did the study find? The King's College researchers wanted to gather information on possible coronavirus symptoms to help experts better understand and fight the disease. Of those reporting one or more symptoms of coronavirus to the Covid Symptom Tracker app: 53% said they had fatigue or tiredness 29% persistent cough 28% shortness of breath 18% loss of sense of smell or taste 10.5% suffered from fever Of these 400,000 people, 1,702 said they had been tested for Covid-19, with 579 receiving a positive result and 1,123 a negative one. Among the ones who had coronavirus infection confirmed by a positive test, three-fifths (59%) reported loss of smell or taste. © 2020 BBC

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27157 - Posted: 04.01.2020

By Erin Garcia de Jesus Myriad microbes dwell on human tongues — and scientists have now gotten a glimpse at the neighborhoods that bacteria build for themselves. Bacteria grow in thick films, with different types of microbes clustered in patches around individual cells on the tongue’s surface, researchers report online March 24 in Cell Reports. This pattern suggests individual bacterial cells first attach to the tongue cell’s surface and then grow in layers as they form larger clusters — creating miniature environments the different species need to thrive. “It’s amazing, the complexity of the community that they build right there on your tongue,” says Jessica Mark Welch, a microbiologist at the Marine Biological Laboratory in Woods Hole, Mass. Methods to identify microbial communities typically hunt for genetic fingerprints from various types of bacteria (SN: 11/05/09). The techniques can reveal what lives on the tongue, but not how the bacterial community is organized in space, Mark Welch says. So she and her colleagues had people scrape the top of their tongues with plastic scrapers. Then the team tagged various types of bacteria in the tongue gunk with differently colored fluorescent markers to see how the microbial community was structured. Bacterial cells, largely grouped by type in a thick, densely packed biofilm, covered each tongue surface cell. While the overall patchwork appearance of the microbial community was consistent among cells from different samples and people, the specific composition of bacteria varied, Mark Welch says. © Society for Science & the Public 2000–2020.

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27141 - Posted: 03.25.2020

By Eva Frederick They’re the undertakers of the bee world: a class of workers that scours hives for dead comrades, finding them in the dark in as little as 30 minutes, despite the fact that the deceased haven’t begun to give off the typical odors of decay. A new study may reveal how they do it. “The task of undertaking is fascinating” and the new work is “pretty cool,” says Jenny Jandt, a behavioral ecologist at the University of Otago, Dunedin, who was not involved with the study. Wen Ping, an ecologist at the Chinese Academy of Sciences’s Xishuangbanna Tropical Botanical Garden, wondered whether a specific type of scent molecule might help undertaker bees find their fallen hive mates. Ants, bees, and other insects are covered in compounds called cuticular hydrocarbons (CHCs), which compose part of the waxy coating on their cuticles (the shiny parts of their exoskeletons) and help prevent them from drying out. While the insects are alive, these molecules are continually released into the air and are used to recognize fellow hive members. Wen speculated that less of the pheromones were being released into the air after a bee died and its body temperature decreased. When he used chemical methods of detecting gases to test this hypothesis, he confirmed that cooled dead bees were indeed emitting fewer volatile CHCs than living bees. © 2020 American Association for the Advancement of Science.

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 15: Language and Lateralization
Link ID: 27138 - Posted: 03.24.2020

By Roni Caryn Rabin A mother who was infected with the coronavirus couldn’t smell her baby’s full diaper. Cooks who can usually name every spice in a restaurant dish can’t smell curry or garlic, and food tastes bland. Others say they can’t pick up the sweet scent of shampoo or the foul odor of kitty litter. Anosmia, the loss of sense of smell, and ageusia, an accompanying diminished sense of taste, have emerged as peculiar telltale signs of Covid-19, the disease caused by the coronavirus, and possible markers of infection. On Friday, British ear, nose and throat doctors, citing reports from colleagues around the world, called on adults who lose their senses of smell to isolate themselves for seven days, even if they have no other symptoms, to slow the disease’s spread. The published data is limited, but doctors are concerned enough to raise warnings. “We really want to raise awareness that this is a sign of infection and that anyone who develops loss of sense of smell should self-isolate,” Prof. Claire Hopkins, president of the British Rhinological Society, wrote in an email. “It could contribute to slowing transmission and save lives.” She and Nirmal Kumar, president of ENT UK, a group representing ear, nose and throat doctors in Britain, issued a joint statement urging health care workers to use personal protective equipment when treating any patients who have lost their senses of smell, and advised against performing nonessential sinus endoscopy procedures on anyone, because the virus replicates in the nose and the throat and an exam can prompt coughs or sneezes that expose the doctor to a high level of virus. Two ear, nose and throat specialists in Britain who have been infected with the coronavirus are in critical condition, Dr. Hopkins said. Earlier reports from Wuhan, China, where the coronavirus first emerged, had warned that ear, nose and throat specialists as well as eye doctors were infected and dying in large numbers, Dr. Hopkins said. © 2020 The New York Times Company

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27135 - Posted: 03.23.2020

Amy Schleunes Preti was a leading expert on human odors who sought to understand the chemistry of odor in the underarm and the behavior aspects of human scents, and an ambassador to patients suffering from rare metabolic diseases who provided communities worldwide with knowledge about their condition and how to cope with it. Preti was also dedicated to using odor biomarkers to detect cancer in its early stages, contributing both research and money to the cause, according to a Monell Center press release. Born on October 7, 1944 in Brooklyn, New York, Preti received a bachelor’s degree in chemistry from the Polytechnic Institute of Brooklyn in 1966. He then went on to MIT, where he earned a PhD in chemistry in 1971. His thesis was titled, “A Study of the Organic Compounds in the Lunar Crust and in Terrestrial Model Systems,” according to the Monell Center’s statement. Preti coauthored a paper published in Science on the same topic, and reportedly saved a vial of “moon dust” that he sometimes showed off to visitors to his lab. Upon completing his doctorate in 1971, he immediately accepted a postdoc at Monell and later become a member of the Monell Chemical Senses Center and an adjunct professor at the University of Pennsylvania School of Medicine. While Preti and his colleagues investigated a range of odors in different species—anal sac emissions from dogs, scent marks by marmoset monkeys, urine from guinea pigs and mice—Preti’s main focus was on the meaning of human odors. He studied the scents of human underarms and melanoma cells as well as the odors associated with generalized stress. Along with his collaborator, Charles Wysocki, Preti published papers on how human physiology and behavior are affected by body odor. Preti was skeptical of human pheromones and their associated hype, telling The Scientist in 2018, “I am not compelled by any studies that are out there that say there is an active steroid component from the underarm that causes [sexual attraction].” © 1986–2020 The Scientist

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27133 - Posted: 03.23.2020

By Maria Temming When it comes to identifying scents, a “neuromorphic” artificial intelligence beats other AI by more than a nose. The new AI learns to recognize smells more efficiently and reliably than other algorithms. And unlike other AI, this system can keep learning new aromas without forgetting others, researchers report online March 16 in Nature Machine Intelligence. The key to the program’s success is its neuromorphic structure, which resembles the neural circuitry in mammalian brains more than other AI designs. This kind of algorithm, which excels at detecting faint signals amidst background noise and continually learning on the job, could someday be used for air quality monitoring, toxic waste detection or medical diagnoses. The new AI is an artificial neural network, composed of many computing elements that mimic nerve cells to process scent information (SN: 5/2/19). The AI “sniffs” by taking in electrical voltage readouts from chemical sensors in a wind tunnel that were exposed to plumes of different scents, such as methane or ammonia. When the AI whiffs a new smell, that triggers a cascade of electrical activity among its nerve cells, or neurons, which the system remembers and can recognize in the future. Like the olfactory system in the mammal brain, some of the AI’s neurons are designed to react to chemical sensor inputs by emitting differently timed pulses. Other neurons learn to recognize patterns in those blips that make up the odor’s electrical signature. © Society for Science & the Public 2000–2020

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27126 - Posted: 03.17.2020

By Jonathan Lambert To a sea turtle, plastic debris might smell like dinner. As the plastic detritus of modern human life washes into oceans, marine creatures of all kinds interact with and sometimes eat it (SN: 11/13/19). Recent research suggests that this is no accident. Plastic that’s been stewing in the ocean emits a chemical that, to some seabirds and fish, smells a lot like food (SN: 11/9/16). That chemical gas, dimethyl sulfide, is also produced by phytoplankton, a key food source for many marine animals. Now, scientists have determined that loggerhead sea turtles may also confuse the smell of plastic with food, according to a study published March 9 in Current Biology. Over two weeks in January 2019, 15 captive loggerheads in tanks were exposed at the water surface to a slew of scents, including the largely neutral scent of water as a control, of food such as shrimp and of new and ocean-soaked plastic. The turtles (Caretta caretta) largely ignored smells of water and clean plastic. But when the scientists puffed air containing scents of either food or ocean-stewed plastic, the reptiles increased their sniffing above water — a typical foraging behavior. In fact, those responses to food and ocean-soaked plastic were indistinguishable to the researchers, suggesting that the plastic can induce foraging behavior in sea turtles, the team says. That might explain why sea turtles get entangled in or eat plastic, which can be harmful. Along with previous research, this study expands the breadth of marine life that may confuse plastic with food. © Society for Science & the Public 2000–2020

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 27111 - Posted: 03.12.2020

By Virginia Morell Dogs’ noses just got a bit more amazing. Not only are they up to 100 million times more sensitive than ours, they can sense weak thermal radiation—the body heat of mammalian prey, a new study reveals. The find helps explain how canines with impaired sight, hearing, or smell can still hunt successfully. “It’s a fascinating discovery,” says Marc Bekoff, an ethologist, expert on canine sniffing, and professor emeritus at the University of Colorado, Boulder, who was not involved in the study. “[It] provides yet another window into the sensory worlds of dogs' highly evolved cold noses.” The ability to sense weak, radiating heat is known in only a handful of animals: Black fire beetles, certain snakes, and one species of mammal, the common vampire bat, all of which use it to hunt prey. Most mammals have naked, smooth skin on the tip of their noses around the nostrils, an area called the rhinarium. But dogs’ rhinaria are moist, colder than the ambient temperature, and richly endowed with nerves—all of which suggests an ability to detect not just smell, but heat. To test the idea, researchers at Lund University in Sweden and Eotvos Lorand University in Hungary trained three pet dogs to choose between a warm (31 C degrees) and an ambient-temperature object, each placed 1.6 meters away. The dogs weren’t able to see or smell the difference between these objects. (Scientists could only detect the difference by touching the surfaces.) After training, the dogs were tested on their skill in double-blind experiments; all three successfully detected the objects emitting weak thermal radiation, the scientists reveal today in Scientific Reports. © 2020 American Association for the Advancement of Science

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 5: The Sensorimotor System
Link ID: 27081 - Posted: 02.28.2020

John Henning Schumann As the owner of a yellow lab named Gus, author Maria Goodavage has had many occasions to bathe her pooch when he rolls around in smelly muck at the park. Nevertheless, her appreciation for his keen sense of smell has inspired her write best-selling books about dogs with special assignments in the military and the U.S. Secret Service. Her latest, Doctor Dogs: How Our Best Friends Are Becoming Our Best Medicine, highlights a vast array of special medical tasks that dogs can perform — from the laboratory to the bedside, and everywhere else a dog can tag along and sniff. Canines' incredible olfactory capacity — they can sniff in parts per trillion — primes them to detect disease, and their genius for observing our behavior helps them guide us physically and emotionally. Goodavage spoke with NPR contributor John Henning Schumann, a doctor and host of Public Radio Tulsa's #MedicalMonday about what she has learned about dogs in medicine What led you to look into dogs in medicine? I've been reading and writing about military dogs and Secret Service dogs for many years now, and it was sort of a natural next step. These are dogs on the cutting edge of medicine. They're either working in research or right beside someone to save their life every day. And really, doctor dogs are, for the most part, using their incredible sense of smell to detect diseases. And if they're paired with a person, they bond with that person to tell them something that will save their life. © 2020 npr

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 26992 - Posted: 01.25.2020

By Tina Hesman Saey Some hairy cells in the nose may trigger sneezing and allergies to dust mites, mold and other substances, new work with mice suggests. When exposed to allergens, these “brush cells” make chemicals that lead to inflammation, researchers report January 17 in Science Immunology. Only immune cells previously were thought to make such inflammatory chemicals — fatty compounds known as lipids. The findings may provide new clues about how people develop allergies. Brush cells are shaped like teardrops topped by tufts of hairlike projections. In people, mice and other animals, these cells are also found in the linings of the trachea and the intestines, where they are known as tuft cells (SN: 4/13/18). However, brush cells are far more common in the nose than in other tissues, and may help the body identify when pathogens or noxious chemicals have been inhaled, says Lora Bankova, an allergist and immunologist at Brigham and Women’s Hospital in Boston. Bankova and her colleagues discovered that, when exposed to certain molds or dust mite proteins, brush cells in mice’s noses churn out inflammation-producing lipids, called cysteinyl leukotrienes. The cells also made the lipids when encountering ATP, a chemical used by cells for energy that also signals when nearby cells are damaged, as in an infection. Mice exposed to allergens or ATP developed swelling of their nasal tissues. But mice that lacked brush cells suffered much less inflammation. Such inflammation may lead to allergies in some cases. The researchers haven’t yet confirmed that brush cells in human noses respond to allergens in the same way as these cells do in mice. © Society for Science & the Public 2000–2020

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 11: Emotions, Aggression, and Stress
Link ID: 26974 - Posted: 01.21.2020