Two United States researchers on Monday shared the $1 357 839 Nobel prize for physiology or medicine for their discovery of the molecular machinery behind the scent of lilac in the spring, the bouquet of a vintage burgundy or the smell of napalm in the morning.
Richard Axel (58) of the Howard Hughes medical institute at Columbia University, New York, and Linda Buck (57) now of the Fred Hutchinson cancer research centre in Seattle, Washington, in 1991 discovered a family of 1 000 genes that order the proteins that are linked with specific smells.
Humans can remember and identify up to 10 000 smells. The olfactory system plays a powerful role in warning of danger, in identifying fresh food, and linking mother to newborn infant.
”When something tastes really good, it is primarily activation of the olfactory system which helps us detect the qualities we regard as positive. A good wine or a sunripe wild strawberry activates a whole array of odorant receptors, helping us to perceive the different odorant molecules,” said the Nobel citation on Monday.
”A unique odour can trigger distinct memories from our childhood or from emotional moments — positive or negative — later in life. A single clam that is not fresh and will cause malaise can leave a memory that stays for years, and prevent us from ingesting any dish … with clams in it.”
The Nobel award is the biggest prize in science, given for research that breaks new ground. ”Until Axel and Buck’s studies the sense of smell was a mystery,” said Professor Sten Grillner of the Karolinska Institute panel in Stockholm, which selects the medicine prizewinners.
The two scientists worked together on mice to identify the 1 000 genes involved in distinguishing, for example Chanel No 5 from Brut, or grand cru from second-rate plonk.
A sense of smell is vital to all mammals: humans have fewer olfactory genes than rodents, but the olfactory area in the brain of a dog is some 40 times larger than in humans.
The two scientists showed that 3% of human genes are used to make the different smell detector cells. Then, working separately, they showed that every single olfactory receptor cell expresses one and only one of the receptor genes.
Each cell reacts to several related molecules, with varying intensity. Because most scents are mixtures of smells, they ”play” on a range of smell receptors, allowing humans to distinguish and remember a huge range of aromas.
”Before this work very little was known about how we smell. The discovery of this large family of genes has revolutionised our understanding of this major sense. Although this work is not directly related to any major human diseases, it has opened new windows on the way the brain interprets the world around us and how this affects behaviour,” said Peter Brennan, of the University of Cambridge.
”Smell is different from the other senses in that the sensory cells are continually dying and being replaced by new cells that have to be wired up correctly in the brain. Their work, and that of their co-workers, has increased our knowledge of how the complex patterns of connections in the brain are formed during development.” – Guardian Unlimited Â