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Journalism of Courage
The 2004 Nobel Prize for Physiology or Medicine was awarded on Monday to two American researchers for their discovery of how we recognise individual scents and how those scents can transport us in memory to past times and places. Dr. Richard Axel of Columbia University and Linda B. Buck of the Fred Hutchinson Cancer Research Center in Seattle shared the award for their joint discovery of a large family of odour receptors in the nose, each of which responds uniquely to a given scent.
Collectively, those responses produce a distinctive, identification in the brain in much the same way that the letters of the alphabet combine to produce unique words. Until Axel and Buck published their research in 1991, how the sense of smell operated ‘‘was a mystery,’’ said Sten Grillner of the Nobel Assembly, which selects the recipients of the award.
Buck was an immunologist by training who decided she needed to learn how to do molecular biology. To pick up the techniques, she applied for a postdoctoral position in Axel’s laboratory at Columbia. He said she could come only if she worked on neuroscience. Out of that simple encounter was born the first understanding of how smell works.Using newly developed technology, Axel and Buck decided to look for the genes that serve as blueprints for proteins.
They found that the mouse genome contains nearly 1,000 genes that code for individual odour receptors. Each of the 5 million neurons in the nasal cavity has only one of those sensors. When an odour is encountered, the scent molecule may activate anywhere from a handful to hundreds of receptors, producing a unique and characteristic signature that is transmitted to the brain through structures, called glomeruli, in the olfactory bulb of the brain. Using various combinations of 350 nasal receptors, humans are able to recognize 10,000 different scents, and perhaps many times the number.—LATWP
