Directed evolution is a process wherein the sequence of a gene is varied randomly by any of a number of methods generating a library of mutated genes. These mutated genes are expressed and the functions of those gene products are assayed. A selection procedure is then applied to select those genes that express products with desirable functions. These genes are then selectively amplified and the mutagenesis, screening and selection process is repeated until gene products with the most desirable functions are obtained. It is often the case that the screening process involves exciting genes with light and observing the fluorescence from these genes or from molecules they make or associate with. This screening process is usually visual, which is slow and not amenable to automation. This greatly limits the number of cells that can be selected. When electronic cameras have been used to record fluorescence levels from colonies, only the total relative yield of the fluorescence is recorded, which does not distinguish between fluorescence amplitude, related to the concentration of the fluorophore, and fluorescence lifetime, related to the chemical properties of the fluorophore. It is almost always the case that directed evolution procedures select for changes in either the amount of or the chemical properties of the gene, but never both. Thus the capability of performing directed evolution using a fluorescent assay that was both amenable to automation and would distinguish between fluorescence amplitude and fluorescence lifetime is a significant asset not only for research but for diagnostics and therapeutics as well.Researchers at Arizona State University have devised certain a distinct method using fluorescence & optical techniques for screening large numbers of individual cells or colonies of cells that yields fluorescence lifetime data. Analysis of this data is controlled and performed in an automated and rapid manner. This screening method can then be used in cell selection procedures in conjunction with additional methodologies based on their fluorescent properties, which were also developed by the research group. Using these new methods, one can kill cells in a uniquely selective manner, thus promoting the selective survival of the remaining cells. This invention provides represents a distinct improvement over current screening methods as automated scanning enables a large number of colonies to be screened rapidly and automatically. In principle, a slide containing millions of cells could be examined in minutes. This technology carries strong implications for diagnostics and the development of treatment modalities for diseases associated with gene mutations such as cancer and other diseases that are based on genetic pre-dispositions.
|Original language||English (US)|
|State||Published - Jun 13 2000|