Linda Buck

Stockholm, Oct. 4 (Reuters): US scientists Richard Axel and Linda Buck won the 2004 Nobel prize for medicine or physiology today for work on genes that control the sense of smell ? explaining how we recall months later the scent of a lilac.

The two found a gene pool which contains the blueprint for receptors or sensors in the nose that identify odours. They published their fundamental study in 1991.

?The sense of smell long remained the most enigmatic of our senses. The basic principles for recognising and remembering about 10,000 different odours were not understood,? said the Nobel Assembly of Stockholm?s Karolinska university hospital, in its citation for the 10 million crown ($1.38 million) award. ?Until Axel and Buck?s studies the sense of smell was a mystery,? said Prof. Sten Grillner of the Karolinska?s panel.

The two described a large family of 1,000 different genes, three per cent of the total in the human body, that give rise to an equivalent number of sensors in the nose that identify smells, known as ?olfactory receptor types?.

These sensors sit on cells in the back part of the nose and are responsible for identifying smells. Each receptor cell has only one type of odorant receptor, which can detect a limited number of types of smell.

The receptor cells then send signals back to the parts of the brain responsible for smell. ?Therefore, we can consciously experience the smell of a lilac flower in the spring and recall this olfactory memory at other times,? the citation added.

The award said Colombia University professor Axel, 58, and 57-year-old Buck, of the Fred Hutchinson Cancer Research Centre in Seattle, had clarified the olfactory system from the molecular level to the organisation of the cells.

The award, given since 1901, is formally called the prize for medicine or physiology ? the study of living organisms. Hans Jornvall, secretary of the Nobel Committee at the Karolinska, said that in this sense the award was a ?true physiology prize for humanity, something we use every day?.

Fellow Karolinska expert Prof. Tomas Olsson said their discoveries had led to no medical breakthroughs.