Reporter 453, 5 June 2000

Yeast offers a new diagnostic toolkit

Molecular biologist John Findlay’s work has led to a remarkable diagnostic procedure based on the sex life of yeast, which may soon help pinpoint deadly chemicals in our bodies and the environment.

The team is working with yeast cells, which use receptors to detect chemicals given off by other yeast cells. By taking the receptor protein gene and mutating it, Professor Findlay’s team found the receptors reacted to the presence of a vast range of different chemicals.

The team used a genetically-engineered yeast strain where the receptor protein relases a special molecule that turned the cell blue. This formed the basis for the sensor.

Professor Findlay’s research could have wide-ranging uses, from detecting chemicals on a patient’s breath which confirm the presence of stomach ulcers to indicating levels of air pollution.

Similarly, the technique can be applied to betray the presence of illegal drugs in the body of, say, a motorist or an athlete, more rapidly than conventional blood or urine testing.

Chemical traces present in the tested samples, whether of human breath or the air in the vicinity of a factory chimney, cause the yeast cells to change colour if the substances they have been engineered to ‘recognise’ are present. The normal function of the receptor protein is to seek out the pheromones given off by other yeast cells nearby.

Tests are under way to build up a library of mutant yeast sensors which will change colour in response to the presence of a wide range of chemicals, perhaps in concentrations as small as one or two parts per million.

The patented technique developed from Professor Findlay’s research on cell membranes, the protective ‘skin’ which envelops them. The membranes house the long protein receptors which usually help the yeast cells find a mate - and now can also help detect disease and pollution.

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