In the study, researchers ran side-by-side comparisons between Candida and baker's yeast -- an organism that doesn't typically infect humans -- in order to find the genes that Candida uses to protect itself against nitric oxide, or NO. Human immune cells give off NO to slow the growth of yeast colonies. The study, published in this month's issue of the journal Eukaryotic Cell, isolated one gene that appears to play a critical role in Candida's NO defense.
The researchers determined that Candida, unlike baker's yeast, is able to sense the presence of NO and ramp up its defenses. They are currently trying to determine which chemical signals Candida uses to detect the presence of NO.
"Baker's yeast and Candida both have the gene to make NO-scavenging enzymes, but Candida has three copies, and it alone has a mechanism to react to increased NO levels by producing more NO-scavengers," said lead researcher Mike Gustin, associate professor of biochemistry and cell biology. "If we can identify the signaling mechanism it uses, that would give us one more useful target for new drug therapies."
Candida is common in humans. It's estimated that 70 percent of people have Candida colonies in their intestines, mouths or on their skin. In most cases, the organism is commensal, meaning it does not harm people, even though it depends upon them for food. However, colonies of Candida sometimes grow too large, as happens in the case of yeast infections. While not life-threatening, vaginal yeast infections are a common and painful problem for a significant percentage of Ame
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Contact: Jade Boyd
jadeboyd@rice.edu
713-348-6778
Rice University
25-Jun-2004