Scientists win Nobel Prize for gene technology

Three scientists, two Americans and a Briton, won the 2007 Nobel Prize in medicine for their work on creating "knockout" mice. Mario R. Capecchi of the University of Utah in Salt Lake City; Oliver Smithies of the University of North Carolina in Chapel Hill and Sir Martin J. Evans of the Cardiff University in Wales developed the immensely powerful knockout technology, which allows scientists to create animal models of human disease in mice. The knockout technique provides researchers with a new tool for finding out what any given gene does. It allows them to genetically engineer a strain of mice with the gene missing, or knocked out, then watch to see what the mice can no longer do. After the first decoding of the mouse and human genomes in 2001 yielded thousands of new genes of unknown function, knockout mice became a prime source of information for making sense of these novel genes. Most human genes can also be studied in this way through their counterpart genes in the mouse. Mice have been likened to pocket-size humans, because they have the same organs and their genes are about 95 per cent identical in sequence. Scientists have developed more than 500 mouse models of human ailments, including those affecting the heart and central nervous system, as well as diabetes, cancer and cystic fibrosis. Scientists can now use the technology to create genetic mutations that can be activated at specific time points, or in specific cells or organs, both during development and in the adult animal. Gene-targeting technology can knock out single genes to study development of the embryo, aging and normal physiology. So far, more than 10,000 mouse genes, or about half of those in the mammalian genome, have been knocked out. Researchers can also make conditional knockouts, mice in which a gene of interest can be inactivated in a specific tissue or part of the brain, at any stage in life. Another important variation is to tag a normal gene with a so-called reporter gene that causes a visible colour change in all cells where the normal gene is switched on.