24 Nov 1997

Researchers at California-based Affymetrix have analyzed the activity of every gene in the yeast genome in a single experiment using a new "DNA chip." This remarkable technological feat hints of a future, following completion of the Human Genome Project, when scientists will be able to read a person's genetic profile instantaneously using pocket-sized devices. Using an integrated device consisting of a grid of short DNA probes, in which each probe in essence corresponds to a different gene of the yeast chromosome, David Lockhart and his colleagues are able to monitor all 6,200 genes in baker's yeast simultaneously. The chip registers the production of messenger RNAs (a direct indication of a gene's activity) using fluorescent tags. The intensity of the fluorescent glow indicates the amount of that mRNA in a cell-so highly induced genes glow more brightly than genes that are barely active. To make the chip, the Affymetrix team had to perform the technological feat of cramming 260,000 DNA sequences into an area of about two centimeters square. The technique should be applicable to any organism whose complete genome sequence is known, including, within the next 5-10 years, humans.—June Kinoshita