Dr Julie Ahringer, American geneticist, studying a dividing cell with a light microscope. Dr Ahringer and her team from the Wellcome Trust/Cancer Research UK Institute of Cancer and Developmental Biology at Cambridge University have used a technique known as RNA interference (RNAi) to determine the function of genes in the worm C. elegans. Introducing short segments of double stranded RNA into a cell prevents the corresponding gene from functioning. Studying the effects of this silencing allows the gene's function to be determined. Dr Ahringer has built a library of bacteria containing RNA segments for each of the worm's genes, which can be used by scientists worldwide to study their function.