My sister, a medical student who has worked in a pathology lab, recently mentioned in passing that specific strains of bacteria, grown in an incubator, can have some pretty unusual smells. When I asked what she meant, she drew me this table (on some handy Discover stationary).
Now, I’ve grown plenty of yeast in my day, and they just smell like gym socks. Maybe, if you get some wild ones in there, like gym shorts (I’ve never enjoyed fancy beer made with wild yeast. Too redolent of crotch).
This level of olfactory whimsy, then, was totally new to me: Pseudomonas aeruginosa smells like flowers? Streptococcus milleri smells of browned butter? Clostridium difficule, scourge of elderly intestines, bringer of fecal transplants, smells like horse poo? I’ll confess, I never quite thought about what happens when you get millions of a single kind of bacteria all together in one place and take a nice long sniff. I did not think it would ever be pleasant. I was wrong.
One of these pockets must have Tabasco.
Does this zero gravity make me look fat? Yup. It’s called the Charlie Brown effect, according to Michele Perchonok, NASA’s shuttle food system manager, and it’s not because she’s fattening them up with shrimp cocktail and chicken consommé. Without the benefit of gravity, bodily fluids accumulate in the head, giving the astronauts rounder, cartoon-like faces.
As anyone who’s had a cold knows, more fluid in our facial cavities also means congestion and weakening our sense of smell. But is lack of gravity actually responsible to for all this? There’s only one way to find out: “Perchonok has asked [food engineer Jean Hunter] and her crew at Cornell to test the stuffy nose theory. To do that on Earth, volunteers will spend several weeks in a bed where their heads are lower than their feet to try to re-create that Charlie Brown effect.” This might not be what people had in mind when they volunteered for astronaut simulations.
Spotted hyenas are sometimes portrayed as cowardly scavengers, always laughing, always up to some kind of mischief. If you’ve ever seen Disney’s The Lion King, then you may already have that image in your head. Here in the non-Disney universe, spotted hyenas are actually fascinating creatures. For example, they hang out in matriarchal “clans,” and the females, with their aggressive behavior and pseudo-penises (large clitorises), are very difficult to tell apart from the males. But it turns out that spotted hyenas may be even stranger than we initially thought: they may use bacteria to help communicate with one another, suggests Michigan State University zoologist Kay E. Holekamp in a recent, amusing New York Times blog post.
“Refreshing” orange scent perked dancers right up.
Air fresheners aren’t just for Grandma anymore.
Dutch scientists suggest that as smoking bans mean club-goers can now smell all the nasty beer, puke, sweat, and so on in nightclubs, owners may want to spritz their businesses with “carefully selected fragrances [that] can enhance dancing activity, improve the overall perception of the evening, and improve how nightclub goers rate the music as well as their mood,” as a press release puts it. In true scientific fashion, the researchers then went clubbing to test their hypothesis.
The humble fruit fly is overturning the science of smell. Using the fruit fly’s sensitive schnoz, scientists now have evidence that the sense of smell isn’t only a matter of molecular shape–it might also have something to do with how the molecules entering the nose vibrate.
Previously, scientists thought that we perceive a particular smell when an olfactory molecule’s shape matches the shape of receptors in our nose. The molecule enters the receptor, and so we perceive the particular smell triggered by that lock-and-key scenario. But in 1996, MIT Biophysicist Luca Turin suggested that the patterns in which molecules vibrate are what control odor.
But the problem is, to detect an abnormal stench, the government first needs to know the city’s normal aroma, to have an idea of its “chemical profile.” To that effect, DARPA just released a solicitation looking for suggestions on how to best build chemical composition maps of major United States cities. Spencer Ackerman over at Wired’s Danger Room t0ok a look at the solicitation and explained what DARPA is looking for:
The data Darpa wants collected will include “chemical, meteorological and topographical data” from at least 10 “local urban sources,” including “residences, gasoline stations, restaurants and dry cleaning stores that have particular patterns of emissions throughout the day.”
Then, subsequent chemical readings from the area could be compared to the “map” to check for abnormal chemicals in the air. Since many chemicals that can be used in a terrorist attacks are normally found around our cities, it’s difficult to just screen for them without having an idea of their baseline levels, explains Wired:
By Rose Eveleth
Bomb squads have long used metal detectors, x-ray machines, and dogs to uncover threats. Without these tools, authorities may not have intercepted some of the thirteen homemade explosives that froze Greece’s outgoing mail earlier this week. But soon they may have a new tool to help find the bad guys and their bombs: microscopic worms.
In a paper published last month, researchers at Australia’s Commonwealth Scientific and Industrial Research Organization described the effectiveness of Caenorhabditis elegans–a millimeter-long, mud-loving nematode–in detecting chemicals associated with explosives. If they’re right, bomb detection could get cheaper and easier. But not everyone is convinced.
This nematodes isn’t the first organism investigated for its keen sense of smell. Dogs, rats, pigs, cows, insects, bacteria, and even plants have been used to find explosives. So far, nothing has worked as well as the trusty canine snout.
But according to lead researcher Stephen Trowell, a machine that uses his worms could surpass all these in sensitivity. “All signs are that it’s as good as it gets,” he said.
The nematodes smell chemicals like nitroglyceride and cyclohexanone—both found in the air around homemade C4 explosives—through tiny scent organs on the sides of their mouths called amphids. Each amphid has twelve different kinds of receptors that relay signals to the brain.
Do I smell a banana? Nope. It’s a blue light I’m smelling.
Fruit fly larvae made this mistake while participating in a study recently published in Frontiers in Neuroscience Behavior. By adding a light-sensitive protein to certain smell receptors in the larvae, German scientists allowed the genetically engineered bugs to essentially smell light.
The team, under the guidance of Klemens Störtkuhl at Ruhr University Bochum, is attempting to understand “olfactory coding”–how the brain transforms chemical signals into perceptible smells. Normally, a fly’s olfactory receptor neurons only send an electrical signal to its brain when the fly smells something, but by adding a protein the researchers caused a neuron to fire when the one-millimeter bug was basking in blue light.
The fly brain uses some of its 28 olfactory neurons to detect bad smells, and others for good ones. Protein puppeteers, the researchers could pick which neuron to add the light-sensing protein to. The good-smelling neurons respond to a smorgasbord of fly-friendly scents: like banana, marzipan, and glue (apparently rotting fruit gives off these scents). By attaching the light-sensitive protein to one of these neurons, researchers caused the typically light-fearing insects to crawl straight towards the blue glow.
According to a ScienceDaily article, given their successful mapping of these larvae olfactory neurons, the researchers next hope to make adult fruit flies go bananas.
Discoblog: Neuroscientist Says We Perceive “Smounds”—Half Sound, Half Smell
80beats: A Life-Extending Coup: Flies That Can’t Smell Food Live 30 Percent Longer
Not Exactly Rocket Science: Smell a lady, shrug off flu – how female odours give male mice an immune boost
Not Exactly Rocket Science: Elephants smell the difference between human ethnic groups
DISCOVER: The Brain: The First Yardstick for Measuring Smells
Image: flickr / Jason Gulledge
They change their clothes frequently. They shower repeatedly, sometimes using a whole bar of soap in one go. Some even swallow perfume.
They think they smell bad, but they don’t.
Olfactory reference syndrome is a rare psychiatric disorder, but it can lead to isolation, depression, and suicide. It’s also a little-noticed, little-studied syndrome. But now a study to appear in Depression and Anxiety has looked at twenty sufferers and reviewed current literature on the disorder to determine its general characteristics.
Psychiatrists have known about the disorder’s symptoms for over a century, but treatment and diagnosis are difficult, in part because the syndrome doesn’t currently have its own classification in Diagnostic and Statistical Manual of Mental Disorders (DSM)–the handbook of mental health professionals. The manual combines the syndrome with other disorders, such as social phobia, delusional disorder, body dysmorphic disorder, and obsessive-compulsive disorder. The new study gives recommendations for updating the next version of the manual, and suggests adding this disorder to an appendix of conditions that need further research.
Struggling for a gift idea? How about gifting a rat through “Adopt-a-HeroRat.” These are no regular New York City-type rats, creepily scampering across train tracks or spreading disease; these so-called HeroRats help save lives by sniffing out unexploded landmines in Mozambique. For just six dollars a month, you can choose to support the good work of “Allan,” “Kim,” “Tyson,” or “The Chosen One.”
The rats being used in Mozambique’s mine-sweeping operations are African pouched rats; they’re small, lightweight (weighing about 3 pounds), and, according to the BBC, surprisingly cute. Traditionally, mine-detection has been carried out by metal detectors and sniffer-dogs, but the rats are the latest workers to join the team. However, the mine-removal process is still dangerous and labor-intensive: Once a rat discovers a mine it has to be dismantled by a human.