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 Water world
20.11.2017 | Washington University in St. Louis

nachricht Carefully crafted light pulses control neuron activity
20.11.2017 | University of Illinois at Urbana-Champaign

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>