28 September 1999


by Kate Melville

The coolest, most insightful technology in modern genetics is the gene chip - technology that permits scientists to analyze thousands of genes at once. Currently this can only be done with very expensive equipment (e.g. chips to analyse DNA from specific organisms or tissues can take months to make and cost as much as $12,000 each), but may soon come within reach of most biologists. Not only are the current chips expensive but they are used once and then thrown away

A group of University of Wisconsin-Madison scientists have now found a new way to cheaply and simply manufacture the customized chips capable of deconstructing long segments of DNA. This technique enables biologists to scour huge chunks of animal and plant genomes in search of the genes that promote disease, the genetic switches that govern such biological phenomena as aging, and the DNA codes that permit microorganisms to make antibiotics.

The new technique is known as MAS for Maskless Array Synthesizer. It promises to take the technology and put it in the laboratory of virtually any research biologist. Gene chip technology now depends on photolithography, a process that requires shining ultraviolet light through a series of stencil-like masks onto a glass chip resulting in the synthesis of tens of thousands of DNA molecules of interest.

Each DNA molecule synthesized on such a chip, is like a window to a wealth of genetic information, providing a glimpse of the workings of tens of thousands of genes found in the cells of living organisms.

The new technology capitalises on an off-the-shelf Texas Instruments technology used in overhead projection known as Digital Light Processors. At the heart of the technology is an array of 480,000 tiny aluminum mirrors arranged on a computer chip.

By manipulating the mirrors, the Wisconsin team, found that they could shine light in very specific patterns, eliminating entirely the need for the delicate and expensive masks used in traditional DNA chip technology.

MAS also has the potential to be used to clinically diagnose genetic disease in humans, and so holds great promise for drug discovery schemes, and for the testing of other biological building blocks such as proteins and carbohydrates.