Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Genetic Discovery Paves Way to Decode Sense of Smell in Mammals

24.11.2004


Duke University Medical Center geneticists have discovered new proteins that help the olfactory system in mammals organize properly. Thus the proteins are key to the ability of mammals, including humans, to detect and respond appropriately to chemicals in the environment via their sense of smell. The finding in mice paves the way for scientists to unravel the underlying code that allows the brain to interpret smells, according to the researchers.



Using genetic manipulations, the team found two proteins in mice that chaperone odorant receptors to the surface of olfactory nerves in the nose. Odorant receptors are the protein switches nestled in nerve cell membranes that trigger responses to specific volatile chemicals.

The discovery of the chaperone proteins reveals the first molecular components of the olfactory machinery that promotes proper targeting of olfactory receptors to the neuronal cell surface, said Hiroaki Matsunami, Ph.D., assistant professor of molecular genetics and microbiology at Duke. By taking advantage of the newly discovered components of the olfactory machinery, the Duke researchers have already begun tests to match the nearly 1,000 different mouse odorant receptors with the very specific chemical or chemicals to which they respond.


"In a fundamental way, the manner in which odorant receptors function remains a mystery due to technical difficulties that have largely prevented the necessary experiments," Matsunami said. "The finding of these accessory proteins opens the door toward understanding the mechanisms underlying our sense of smell."

Matsunami and his colleagues reported their results in the November 24, 2004, issue of the journal Cell. The work was supported by the National Institutes of Health and Duke University Medical Center.

Humans and other animals can detect and discriminate among thousands of volatile environmental chemicals. The sense of smell is essential for animals to detect food sources and potential toxins and to identify suitable mates. The sensory ability depends initially on olfactory nerve cells in the lining of the nose.

Scientists first identified olfactory receptors in mammals 10 years ago – a discovery that won the 2004 Nobel Prize in Physiology or Medicine. Each olfactory neuron bears only one type of olfactory protein receptor on its surface, forming the cellular basis for discrimination among smells, Matsunami explained. Mice have as many as 1,000 different odorant receptors, while humans – with a relatively poorer sense of smell – have 350 of the protein receptors for smell. However, the selectivity of those different receptors for chemical stimuli remains unclear, he added.

The researchers’ extensive search for proteins involved in delivering odorant receptor proteins to the surface of olfactory nerves revealed two proteins, which they named receptor transporting proteins one and two (RTP1 and RTP2). The researchers found that genes encoding the proteins were specifically active in olfactory neurons. Furthermore, RTP1 and RTP2 interact with olfactory receptor proteins and enhance their function, they found.

The researchers reported similar, although much weaker effects, for a third protein, which they called receptor expression enhancing protein one (REEP1).

To demonstrate the utility of the accessory proteins for elucidating the sense of smell, the team created cells with constantly high levels of RTP1, RTP2, REEP1, and another protein known to bind olfactory receptors. The enhancement of these protein levels made it possible for the researchers to induce the newly created cells to express odorant receptors at their surfaces. The team then tested the receptors’ response to various chemicals, including the fishy-smelling aliphatic acids and sweet-smelling coumarine and piperonal.

Through these experiments, the researchers identified seven new olfactory receptors that respond to different chemical odorants included in their test panel. The initial results further suggest that the ability to discriminate among chemicals depends on a "combinatorial receptor code," in which one receptor responds to multiple related odorants and one odorant activates multiple receptors, they reported. "These initial findings are just the beginning," Matsunami said. "We have established a system that should allow the rapid identification of chemicals that stimulate olfactory neurons to provide a comprehensive understanding of the mammalian sense of smell."

The research team included Harumi Saito, Momoka Kubota, Richard Roberts and Qiuyi Chi, all of Duke.

Kendall Morgan | EurekAlert!
Further information:
http://www.duke.edu

More articles from Life Sciences:

nachricht A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>