Earlier studies had linked the genes to light-sensing in another distantly related fungal lineage, an indication that the fungal light sensor arose early in evolution and may be shared by many extant fungal species. Other well-studied fungi, such as Saccharomyces cerevisiae, or baker's yeast, have apparently lost their ability to sense light, Heitman said, and have neither of the conserved light-sensing proteins.
"Fungi have many negative implications for human life as they lead to human disease, as well as plant disease and mold," said Idnurm, a post-doctoral fellow at Duke. "However, fungi also play important beneficial roles, for example, as a source of food and pharmaceuticals.
"Therefore, an understanding of the role of environmental signals such as light in fungal development is vital to increase the benefits and decrease the costs that fungi present."
The researchers first tested the importance of genes with known roles in light sensitivity of another, distantly related fungus. Yeast strains lacking one of those genes, known as white collar 1 (BWC1), mated equally well in the light or the dark, implicating that gene in the fungus' ability to sense light. BWC1 also functions in the fungus' resistance to ultraviolet light, they reported. Further study identified a second, related gene, BWC2, that is also required for C. neoformans normal response to both blue and ultraviolet light.
Moreover, the researchers found, mice inoculated with C. neoformans lacking either of the light-sensing genes remained healthy 30 days later, while those infected with the normal fungus died by day 30.
The finding points to novel virulence pathways, Heitman said, as the BWC1 and BWC2 mutants were not impaired for any of the characteristics pr
Source:Duke University Medical Center