Gene expression studies in Candida albicans

Date

2006-12

Journal Title

Journal ISSN

Volume Title

Publisher

Texas Tech University

Abstract

Candida albicans is part of the normal flora of the human oral, gastrointestinal, vaginal and cutaneous surfaces. However, in the compromised host the organism can cause infection of those surfaces as well as systemic disease. C. albicans can also form biofilms on host surfaces as well as abiotic device surfaces such as dentures and catheters. Phenotypic drug resistance of C. albicans biofilms poses a therapeutic dilemma. Stationary phase C. albicans cells are phenotypically more resistant to antifungals. Identifying if cells in a biofilm reach stationary phase could give some insight into the mechanism of biofilm resistance. To test this possibility we first characterized the C. albicans stationary phase and established criteria by which stationary phase could be defined.

Planktonic stationary phase cells in vitro are known to survive for long periods of time in media composed of metabolites excreted by the cells during growth. This conditioned medium also contains quorum sensing molecules that confer various properties to the fungus. However, the global effect on gene expression of either the conditioned medium or any of its individual quorum sensing molecule is not well studied. We studied the mechanism by which the conditioned medium and a quorum sensing molecule affected C. albicans biology.

To study C. albicans stationary phase, we used a variety of descriptive techniques and cDNA microarray technology. We have defined for the first time, the different growth phases of C. albicans and determined the genes and processes important for entry into stationary phase. We have also identified genes important for the survival of cells in stationary phase. Additionally, by establishing an improved extraction protocol that yields RNA of all classes and sizes we have overcome the difficulty associated with extracting RNA from stationary phase cells. Using stationary phase gene markers we demonstrated that even after prolonged incubation, only 40% of the founder cells of a C. albicans biofilm reached stationary phase. The results of this study will expand our existing knowledge of C. albicans stationary phase, and serve as a foundation for more systematic and unbiased studies in C. albicans research.

Description

Keywords

Gene expression, Farnesol, SNO1 stationary phase gene, Stationary, SNZ1 stationary phase gene

Citation