AsianScientist (Feb. 4, 2013) – Researchers in Singapore and the United States have constructed stable haploid strains of Candida albicans, the most prevalent human fungal pathogen.
This discovery, published in the journal Nature last week, was jointly made by two teams of scientists led by Prof Wang Yue of A*STAR’s Institute of Molecular and Cell Biology in Singapore and Prof Judith Berman of the University of Minnesota in the U.S.
Candida albicans ranks among the top four microbial pathogens in hospital-acquired infections of the blood, which has a mortality rate of as high as 45 percent. Currently, the choice of drugs for treating infections by this pathogen is limited, and cases of drug resistance have emerged worldwide.
Nearly all other fungi have a haploid and a diploid phase in their life cycle, enabling the haploid cells to mate and generate genetic variations. But up until now, yeast scientists had been unable to identify a haploid phase of the Candida fungus.
“The scientists show that the human pathogenic yeast Candida albicans, long thought of as always having two copies of each chromosome and no sexual reproduction in its life, in fact can and does exist as a sexually reproducing cell carrying only one copy of its genome,” said Dr. Mohan Balasubramanian, Senior Investigator at Temasek Lifesciences Laboratory.
It is difficult for scientists to carry out genetic screens in diploid fungi as they need to precisely target both copies of a gene to observe a change. With the discovery of the haploid phase, however, scientists will now be able to target just one copy of the gene to observe a change, allowing for the more efficient screening of drug targets.
“Our discovery helps to fill a long missing gap in the life cycle of this important pathogen, greatly advancing our understanding of how it generates genetic variations for evolution and adaptation. At the same time, haploid Candida albicans also allows scientists to carry out traditional genetic screens that will certainly accelerate the identification of genes important for infection and drug targets for medical intervention,” said Prof. Wang.
The article can be found at: Hickman MA et al. (2013) The ‘obligate diploid’ Candida albicans forms mating-competent haploids.
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Source: A*STAR; Photo: AJC1/Flickr/CC.
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