Researchers crack olfactory code for partner selection, synthesise first biologically effective perfume

Feb 01, 2013
Researchers believe that not only the perception of body odour, but also of perfumes, play a role in sexual communication. After all, humans have been using perfumes for more than 5,000 years. Credit: © pixelio.de

(Medical Xpress)—Individual body odour plays an important role in partner selection. Humans, mice, fish and birds, and probably other vertebrates too, receive important information about a potential partner's immune system from their body odour. A partner is chosen on the bases of whether he or she offers the optimum complement to the individual's own immune genes. The aim is to pass on a wide variety of immune genes to the offspring so that they are resistant to a broad spectrum of pathogens. Although several hundred different forms of the immune genes exist in humans, individuals only have a few variants which co-determine their typical body odour, their individual "scent". Scientists from the Max Planck Institutes of Immunobiology and Epigenetics in Freiburg and for Evolutionary Biology in Plön, together with colleagues from the University of Dresden Medical School, have succeeded in explaining the chemical nature of this individual scent, synthesized it and tested its effectiveness on test persons. The results show how perfumes that are completely effective biologically can be produced synthetically without resorting to animal products.

As far back as the 1990s, the Research Group working with Manfred Milinski, now Director at the Max Planck Institute for in Plön, discovered, through the use of so-called t-shirt experiments, that women prefer the smell of men who have different immune gene variants than they themselves have. "We are unconsciously aware of how our own immune system is constituted and can recognise that of a potential partner from their smell," explains Milinski. In further experiments, the researchers were able to show that these immune variants also determine which both women and men prefer in the perfumes they use. Since time immemorial, people have been very selective when it comes to choosing perfumes: They take a long time to find one and tend to stick with their choice for many years. A perfume is selected so that it will intensify the individual's own immunogenetic olfactory signal. "If it would mask or alter the natural signal, selection would have spoiled the fun of using perfume long ago," explains the evolutionary biologist.

Natural perfume ingredients apparently contain chemical imitators of the human immune-gene-dependent olfactory signal. This explains their often rather exotic origins: for example, ambergris is produced from the regurgitated leftovers of sperm whale prey. As natural ingredients, due to their allergenic effects, increasingly have to be replaced by biologically ineffective substitutes, it would be useful to be able to analyse our natural perfume so that it can be synthesised and used as an "original" ingredient in perfumes. However, which molecules could assume the function of the human natural perfume?

In experiments on mice, the Research Group working with Thomas Boehm, Director at the Max Planck Institute of and in Freiburg, and in cooperation with other scientists, succeeded in identifying biologically effective components of the immune-gene-dependent – and in also detecting this mechanism in fish with their colleague Manfred Milinski.

The sensory cells of the olfactory mucosa are actually capable of identifying certain protein ligands known as peptides. These usually supply the immune system with information about pathogenic invasions – and at the same time provide a mirror image of the individual's set of immune genes. This is related to the immune system's recognition mechanism: the protein ligands originating from bacteria, viruses and parasites are bound by MHC (major histocompatiblity complex) molecules, which are encoded through the different immune gene variants.

"The recognition mechanism works on the basis of the key-lock principle, i.e. each MHC molecule has protein ligands that fit it. Therefore, because certain MHC molecules are required to recognise certain peptides, the range of peptides that escape to 'the outside' also reflects the range of MHC molecules," explains Thomas Boehm. This discovery meant that the researchers had cracked the olfactory code. The structure of the protein ligands can be predicted for the human immune molecules.

In their current experiment, the researchers were now able to produce the components of the body odour artificially and test its effectiveness, after having determined the nature of the immune gene variants in female . To this end, the test subjects were asked to mix the artificial protein ligands with their own armpit perspiration and to decide which variant appealed to them most. It emerged that the test subjects identified the underarm perspiration as particularly pleasant and their preferred scent when it had been mixed with the protein ligand corresponding to their own immune gene type.

Working in cooperation with researchers at the Department of Otorhinolaryngology at the University of Dresden Medical School, the scientists then examined whether the olfactory perceptions could be detected in the brain, and if so where in the brain. To this end, the Research Group, working with Ilona Croy and Thomas Hummel, applied synthetic protein ligands of either the test subjects' own or another type, and studied their perception in the brain using functional magnetic resonance imaging. Astonishingly, a small area located in the right middle frontal cortex always responded when the test subjects smelled one of their own peptides.

"These results show that the protein ligands transported by the immune molecules actually determine the natural body odour not only in animals, but also in humans," says Manfred Milinski. These findings offer new possibilities for the production of innovative perfumes that can provide a better signal of an individual's gene repertoire to a potential partner through the intensification of his or her body odour. "This means that, in future, it may be possible to dispense with ingredients of animal origin in classic perfumes," says the Max Planck Director.

Explore further: Synthetic biology on ordinary paper, results off the page

More information: Manfred Milinski, Ilona Croy, Thomas Hummel and Thomas Boehm, Major histocompatibility complex peptide ligands as olfactory cues in human body odour assessment, Proceedings of the Royal Society B, published online January 23, 2013 doi: 10.1098/rspb.2012.2889

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User comments : 12

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JVK
3.7 / 5 (3) Feb 01, 2013
Feedback loops link odor and pheromone signaling with reproduction. http://www.cell.c...900981-5 The link is GnRH. "Indications that GnRH peptide plays an important role in the control of sexual behaviors suggest that pheromone effects on these behaviors might also involve GnRH neurons."
Translation: The epigenetic effects of vertebrate pheromones on GnRH links nutrient-dependent pheromone production and feedback loops to food odors and to pheromones, which control reproduction in species from microbes to man.

Kohl, J.V. (2012) Human pheromones and food odors: epigenetic influences on the socioaffective nature of evolved behaviors. Socioaffective Neuroscience & Psychology, 2: 17338. http://dx.doi.org...i0.17338

Human pheromones: integrating neuroendocrinology and ethology http://www.ncbi.n...11600881

The Mind's Eyes: Human pheromones, neuroscience, and male sexual preferences http://www2.hu-be...kohl.htm

Tausch
1 / 5 (1) Feb 01, 2013
What phase of matter are synthetic protein ligands? Gas?
There are over 500 phases of matter. Which phase does synthetic protein ligands exhibit?

JVK
3 / 5 (2) Feb 01, 2013
What phase of matter are synthetic protein ligands? Gas?
There are over 500 phases of matter. Which phase does synthetic protein ligands exhibit?

It's an open access article. Why don't you read it and learn something about biology, instead of passing more gas here?
Tausch
1 / 5 (1) Feb 02, 2013
Back at you:
The part about polymer physics and Paul Flory is missing in your background.
JVK
3 / 5 (2) Feb 02, 2013
The part about polymer physics and Paul Flory is missing in your background.


What does that have to do with the topic here: "Researchers crack olfactory code for partner selection, synthesise first biologically effective perfume" -- or with anything in their published work or in my published works?
Tausch
1 / 5 (1) Feb 09, 2013
Polymer science makes coding and synthesis possible.
Here an example:
http://phys.org/n...ion.html

If you do not see a connection between odor recognition and the science that supports or does not support this as well as your work or the work of others, simply repeat your statement that you see no connection.

Everyone will then understand how you think and feel.
Everyone will then respond appropriately.



JVK
3 / 5 (2) Feb 09, 2013
Tausch is desperately attempting to change the focus to physics by citing "Odorant shape and vibration likely lead to olfaction satisfaction" in hopes that I don't know enough about the theory to respond by directing others to the book review I published a decade ago "The Emperor of Scent: A Story of Perfume, Obsession and the Last Mystery of the Senses by Chandler Burr
New York: Random House (2003)" see: http://human-natu...urr.html

Tausch apparently knows nothing about biology and would rather those who do did not make scientific progress without addressing ridiculous theories that have nothing to do with epigenetically effected receptor-mediated behavior in species from microbes to man -- unless nutrients and pheromones somehow epigenetically effect the vibration of odor molecules. Is there a model for that? If not, I don't see the connection to this article; to my research interests, or to anything else scientifically supported.
Tausch
1 / 5 (1) Feb 11, 2013
Receptor-mediated behavior is made possible through physics at the molecular scale. No physics, no biology. A molecular vibrational model making the mediation of receptors possible is being propose and challenged by an alternate model:
http://phys.org/n...ory.html

You are closed-minded and your research and dialogue reflects this. Instead you are better off letting me ask the questions and to do the job you were supposed to do and ask as a scientist:

http://phys.org/n...ube.html

All you see is a disconnect.

If you think you have a piece of the puzzle, unless your delusions of grandeur tells you, you have the entire puzzle, then show the rest of the science-related community where your piece dovetails with the rest of the puzzle.

If you do this, see a therapist first for everyone benefit, not just yours. Address yourself first. The 'ridiculous' theories will still be waiting for your return.
JVK
1 / 5 (1) Feb 11, 2013
... show the rest of the science-related community where your piece dovetails with the rest of the puzzle.


I've already done that, and you know it. Human Pheromones: Epigenetic Effects of Odors and Their Affects on Behavior http://f1000.com/.../1092760

This model of systems biology represents the conservation of bottom-up organization and top-down activation via:
1.Nutrient-dependent stress-induced and social stress-induced intracellular changes in the homeostatic balance of microRNA(miRNA) and messenger RNA (mRNA);
2.Intermolecular changes in DNA (genes);
3.Non-random experience-dependent stochastic variations in de novo gene expression for odor receptors;
4.The required gene-cell-tissue-organ-organ system pathway that links sensory input directly to gene activation in neurosecretory cells of the brain;
5.The required reciprocity that links gene expression to behavior that alters gene expression (i.e., from genes to behavior and back).

Okay? Your turn!
Tausch
1 / 5 (1) Feb 12, 2013
My turn for what?
No. Not Okay. Insufficient. Pure Nonsense.
Address yourself first. Get therapeutic help.
I assure you no matter how long you need when you return the 'ridiculous' theories will be there for you to ignore again - if your treatment remains unsuccessful.
JVK
1 / 5 (1) Feb 12, 2013
My turn for what?

Your turn to address the molecular biology of adaptive evolution and explain it through physics, because you want to introduce the vibration theory here.

No. Not Okay. Insufficient. Pure Nonsense.
Address yourself first. Get therapeutic help.
I assure you no matter how long you need when you return the 'ridiculous' theories will be there for you to ignore again - if your treatment remains unsuccessful.


I anticipated the likelihood that you would choose to not take your turn. In itself, that choice tells others that you are touting nonsensical theory with no explanatory power. Do you intend to come back when you can make sense of vibration theory in the context of an olfactory code for partner selection? Or will you simply rear your ugly physics head again at the next opportunity to try and interject theory into discussion of biological facts?
Tausch
1 / 5 (1) Feb 12, 2013
Biological facts stems from physics.
No physics, no biological facts.

A collection of biological facts does not make a theory of adaptive evolution. What did the first cell utilize? Water? Light? Is light a nutrient or a pheromone? Does light change? Did the first cell adapt to changes in light? Does that create cell change? Does that drive adaptive evolution as well?

Why are you second guessing my intentions?
What is wrong with second guessing anyone's intentions?

I intend to provide a foundation for biological facts.
No physics means no biological facts.
A collection of biological facts without theory is useless.
A model without a theory is useless.

You reject physics. You reject theory. I reject a collection of biological facts lacking physics and theory or any collection of facts not pointing to it's foundations.

Savage what you can from your collection biological facts.
Or let it stand as it is, to go extinct.