If the DNA of an organism contains thousands of genes, how do you determine what turns them on and off?
This portion of a DNA microarray is actually smaller than a dime and it was imaged with a laser confocal microscope. We produce these "DNA chips" in my lab and each spot, which contains the DNA sequence of one specific gene, is as thin as a human hair.
Our microarrays are spotted with most of the 6354 genes that are encoded in the genome of a fungal pathogen called Candida albicans. It is the most common cause of yeast infections and, if your immune system is impaired, a painful rash is the least of your worries.
This colorful result was obtained by Celine, my graduate student, as she was studying the effects of an antifungal drug. Red spots indicate the genes that are turned on, the green ones are turned off and those that don't change are yellow. Once we correlate these changes with what we know about the function of the proteins encoded by these genes, we can try to figure out how this perticular drug works.
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