What You smell and what I smell

There are two kinds of people in the world. Those who can smell the roses and those who can’t. Our ability to smell certain odors appears to be hardwired genetically.
In one study, researchers conducted blind smell tests. They then compared the results with participants’ DNA. Detection of four odors—emanating from apples, blue cheese, malt and flowers—could be linked to DNA variations. The studies are publishedCurrent Biology. [Sara R. Jaeger et al, A Mendelian trait for olfactory sensitivity affects odor experience and food selection and Jeremy F. McRae et al, Identification of regions associated with variation in sensitivity to food-related odors in the human genome]

in the journal

A rose-related odor, due to the compound beta-ionone, was described by people with one version of a specific gene as “floral” and “aromatic”. But those with a different variation of the gene said things like “vinegar” and “sour”.
It seems our genes change how we experience the world. That’s important to know if you’re designing soap and want to add a dash of beta-ionone for a fresh floral scent—some consumers may find it disgusting.

As Chris Crockett said: 
Remember that the next time someone finds your homemade apple pie revolting. The fault may lie not in your cooking but in their nose.

Odor as a defensive weapon - for skunks and plants

Everybody knows that skunks can spray a liquid with a strong odor as a defensive weapon. 

Trees can protect themselves with odors as well - but in the opposite way. When they are attackad by insects biting into the leaves, trees emit odors
into the air to attract birds and bees (more exactly carnivorous wasps). 

Remember the scent of a freshly mowed lawn? Or torn leaves?  Similar scents attract various species of birds and insects - depending on the plant and the kind of damage.

In the recent paper, scientists released chickadee-like birds in an orchard of apple trees. Most birds immediately flew to trees infested with caterpillars.
Even if the birds could smell but not see.



REFERENCE

Luisa Amo1,2,*, Jeroen J. Jansen3, Nicole M. van Dam4, Marcel Dicke5, Marcel E. Visser1  Birds exploit herbivore-induced plant volatiles to locate herbivorous prey  Ecology Letters (2013) 16: 1348–1355

Lungs and Smells

Your lungs can smell too.

owever, instead of being used to detect the aroma of blueberry cobbler or a succulent roasting chicken, the odor receptors in the lungs trigger a response designed to protect the airways.
“We forget,” said study author Yehuda Ben-Shahar, “that our body plan is a tube within a tube, so our lungs and our gut are open to the external environment. Although they’re inside us, they

Read more at http://www.redorbit.com/news/health/1113038427/odor-receptors-discovered-in-human-lungs-010314/#3Qkt97vw3WLAxSkI.99

A new study found that receptors we have in the nose are also lining our lungs, membranes of neuroendocrine cells. And these receptors are there to protect us from harmful substances in the air. 

4 years ago, another study found bitter-tasting receptors in the lungs. Every time the bitter taste was detected, our lungs worked hard to sweet the chemicals out of the airways. The recent study explains why smells can cause shortness of breath, chest tightnessand other issues affecting lungs.

ublished in the American Journal of Respiratory Cell and Molecular Biology has revealed that odor receptors aren’t just found in the nose – they also line the lungs as well. However, instead of being used to detect the aroma of blueberry cobbler or a succulent roasting chicken, the odor receptors in the lungs trigger a response designed to protect the airways.
“We forget,” said study author Yehuda Ben-Shahar, “that our body plan is a tube within a tube, so our lungs and our gut are open to the external environment. Although they’re inside us, they’re actually part of our external layer.”
“So they constantly suffer environmental insults, and it makes sense that we evolved mechanisms to protect ourselves,” added Ben-Shahar, and assistant professor of biolo

Read more at http://www.redorbit.com/news/health/1113038427/odor-receptors-discovered-in-human-lungs-010314/#3Qkt97vw3WLAxSkI.99

owever, instead of being used to detect the aroma of blueberry cobbler or a succulent roasting chicken, the odor receptors in the lungs trigger a response designed to protect the airways.
“We forget,” said study author Yehuda Ben-Shahar, “that our body plan is a tube within a tube, so our lungs and our gut are open to the external environment. Although they’re inside us, they

Read more at http://www.redorbit.com/news/health/1113038427/odor-receptors-discovered-in-human-lungs-010314/#3Qkt97vw3WLAxSkI.99

REFERENCES

Philip H Karp, Steven L Brody, Richard A Pierce, Michael J Welsh, Michael J Holtzman, and Yehuda Ben-Shahar (2013) Volatile-Sensing Functions for Pulmonary Neuroendocrine Cells American Journal of Respiratory Cell and Molecular Biology 0 0:ja  

Odor in the City

Brief review of this week's strange odors:

Dallas, Texas — A mysterious odorwas reported this Saturday, December 27th by hundreds of locals.
At about 11:40 a.m., the first call of a "strange chemical odor" came from the Mid State United Recycling facility. It was found that the odor was a result of a byproduct created during the recycling of motor oil.
"Whatever piece of equipment they use for this process heated up to the point that it started venting out of the facility," Evans said.
Evans said HazMat reported the byproduct is not hazardous.
"And it may take some time for the smell to dissipate," he said.
Andy Rodriguez, a resident in the area, said the smell spurred concern.
"I don't know if I should go home or not because I'm not sure if it's gas, or just a smell like gas," she said.
Authorities are still investigating the incident to confirm whether the smell is indeed the result of the motor oil recycling process.

La Jolla, California: A non-profit organization is taking legal action over the noxious odor at La Jolla Cove.

“Citizens for Odor Nuisance Abatement” is suing the city of San Diego, Interim Mayor Todd Gloria and the state of California.

According to the Complaint, the plaintiffs claim it’s the city’s responsibility to keep the public area free of the offensive smell, which it has failed to do.

The group says the city is to blame because of a fence erected along the sidewalk that spans the cove. Because people don’t have access to the rocks anymore, birds and sea lions can climb higher up the bluffs to defecate, they claim.

The complaint alleges that people have become sick and nearby businesses have lost revenue because of the odor. According to the lawsuit, boxer Floyd Mayweather booked two villas and six rooms at the La Valencia hotel, only to leave 15 minutes later because of the smell, costing the hotel more than $5,000 in one day.

Owners of the La Valencia Hotel and George’s By the Cove – two prominent La Jolla businesses – say the city is dragging its feet to fix the smell problem, which many believe is a growing issue.

Some locals that spoke with NBC 7 Friday, December 27, 2013 said the fences designed to keep people off the bluffs are making the sea lions feel more at home in La Jolla, adding to the waste problem.

Mother and son Nancy and Michael Garcia visited La Jolla Cove Friday and said the stench was unbearable

Plainview, New York. The Nassau County Fire Marshal’s Hazardous Materials Division was called to a Plainview neighborhood Wednesday after reports of a noxious odor near the Old Bethpage Village restoration. The division was tasked with determining the source and cause of the smell, which residents described as a mix between rotten eggs, sewage and gas, 1010 WINS’ Gary Baumgarten reported Thursday, December 26, 2013.

New Castle, UK  An investigation is under way after a fire on board a ferry in the North Sea forced it to return to Newcastle.
RAF helicopters winched two passengers and four crew off the MS King Seaways, which was sailing to Amsterdam, when it was 30 miles off Flamborough Head.Passenger Jamie Petterson said that people were "generally very calm and in reasonable spirits" when the initial fire alarm sounded, but that he later encountered "a strong smell of smoke".

You are unique. And so is your sense of smell.

The 400 genes responsible for our olfaction noses can vary greatly  - with more  than 900,000 variations of those genes. And even if your genomes are similar, the receptors can be about 30 percent different.

It's very commonif one person likes a certain smell and the other person doesn't. But a surprise finding by Duke researchers shows that no two people smell things the same way. They are very different at the receptor levels 

Genes code odor receptors, but how are these receptors activated? Researchers from Duke, Rockefeller University, University of Pennsyklvania and Monnell
identified 27 receptors that had a significant response to at least one odorant they used in the study thus doubling the number of known odorant-activated receptors (now 40).

So we are now one little step closer to understanding the consequences of these receptor activation and understanding the sense of smell. 


The missense of smell: functional variability in the human odorant receptor repertoire, Joel D Mainland, Andreas Keller, et al. Nature Neuroscience, Early online Dec. 8, 2013. DOI: 10.1038/nn.3598

Learning to become afraid and passing it to children

Animals can pass on information about a traumatic experience to their offsprings. Researchers at Yerkes National Primate Research Center, Emory University have found that when a mouse learns to become afraid of a certain odor, his or her pups will be more sensitive to that odor, even though the pups have never encountered it. This is an example of an "epigenetic" alteration: transmitted not in the letter-by-letter sequence of the DNA, but in its packaging or chemical modifications.

In mice taught to fear cherry-blossom-smelling chemical
acetophenone, the odorant receptor gene that responds to this compound has a changed pattern of methylation while 
the sequence of the gene encoding the receptor that responds to the odor remained unchanged. And it's all because DNA from the sperm of smell-sensitized mice is altered. As senior author of the study Kerry Ressler says. "There is some evidence that some of the generalized effects of diet and hormone changes, as well as trauma, can be transmitted epigenetically."

Smelling and Aging

Smells affect us in both short- and long-term. In worms and flies, too much smell of the opposite sex can speed up the critter's ageing process and shorten its life. Even if none actually has sex. Similar to the effect of smelling too much good food even without eating it.

The explanation lies in the fact that the fruit fly sperm is toxic and every sexual encounter shortens the lives of females.  If the males were actually allowed to have sex, their lifespans bounced back. Perhaps because od the trade-off between sex and longevity and, more importantly, the clash between expectations and experience.  If we smell food and can’t eat any, the build-up of digestive enzymes can actually cause us harm. Likewise, male flies that smell females but can’t actually mate may suffer the consequences for their unfulfilled expectations.


References 

Sergiy Libert, Jessica Zwiener, Xiaowen Chu, Wayne VanVoorhies, Gregg Roman, and Scott D. Pletcher.

Regulation of Drosophila Life Span by Olfaction and Food-Derived Odors

Science 23 February 2007: 315 (5815), 1133-1137.Published online 1 February 2007 [DOI:10.1126/science.1136610]  

 

 Gendron, Kuo, Harvanek, Chung, Yew, Dierick & Pletcher. 2013. Drosophila Life Span and Physiology Are Modulated by Sexual Perception and Reward. Science http://dx.doi.org/10.1126/science.1243339

Maures, Booth, Benayoun, Izrayelit, Schroeder & Brunet. 2013. Males Shorten the Life Span of C. elegans Hermaphrodites via Secreted Compounds. Science http://dx.doi.org/10.1126/science.1244160