BioProject

Candida albicans, the most common cause of human fungal infections, undergoes a reversible morphological transition from yeast to pseudohyphal and hyphal filaments, which is required for virulence. More...

Candida albicans, the most common cause of human fungal infections, undergoes a reversible morphological transition from yeast to pseudohyphal and hyphal filaments, which is required for virulence. For many years, the relationship between global gene expression patterns associated with determination of specific C. albicans morphologies has remained obscure. Using a strain that can be genetically manipulated to sequentially transition from yeast to pseudohyphae to hyphae in the absence of complex environmental cues and upstream signaling pathways, we demonstrate by whole-genome transcriptional profiling that genes associated with pseudohyphae represent a subset of those associated hyphae and are generally expressed at lower levels; interestingly, no genes appeared to be expressed exclusively in pseudohyphae. Our results also strongly suggest that in addition to dosage, extended duration of filament-specific gene expression is sufficient to drive the C. albicans yeast-pseudohyphal-hyphal transition. Finally, we describe the first transcriptional profile of the C. albicans reverse hyphal-pseudohyphal-yeast transition and demonstrate that this transition not only involves down-regulation of known hyphal-specific genes but also differential expression of additional genes which have not previously been associated with the forward transition, including many involved in protein synthesis. These findings provide new insight into genome-wide mechanisms important for determining fungal morphology and suggest that in addition to similarities, there are also fundamental differences in global gene expression as pathogenic filamentous fungi undergo forward and reverse morphological transitions. Overall design: The Dosage Experiment (13 arrays) was performed twice (two biological replicates). MBY38 cells were treated with various concentrations of Doxycycline (Dox): 20 (n=3), 0.4 (n=1), 0.35 (n=1), 0.3 (n=1), 0.25 (n=1), 0.2 (n=1), 0.15 (n=1), 0.1 (n=1), 0.05 (n=1), 0.02 (n=1) and 0 µg/mL (n=1). Each 20 ug/ml sample was used for 3 technical replicate arrays, one of which was labeled using reverse fluors. The reference sample consisted of equal aliquots of the experimental samples. The Forward Transition Experiment (23 arrays) was performed twice (two biological replicates). MBY38 cells were grown in the presence (n=10) or absence (n=10) of 1.0 ug/ml Dox and subsequently harvested at time points between 1 and 10 hours. Each 1.0 ug/mL Dox treated sample was collected at 0 hours and used for 3 technical replicate arrays, one of which was labeled using reverse fluors. The reference sample consisted of equal aliquots of all 21 experimental samples. The Reverse Transition Experiment (26 arrays) was performed twice (two biological replicates). MBY38 cells were grown in the presence (n=10) or absence (n=10) of 20.0 ug/ml Dox and subsequently harvested at time points between 1 and 10 hours. Each 20.0 ug/mL sample was collected at 0 hours and used for 3 technical replicate arrays, one of which was labeled using reverse fluors. Each untreated (no Dox) sample was collected at 0 hours and used for 3 technical replicate arrays, one of which was labeled using reverse fluors. The reference sample consisted of equal aliquots of all 22 experimental samples. The Dox Control Experiment consisted of 12 arrays. PCY87 cells were grown in the presence (n=5) or absence (n=5) of 20.0 ug/ml Dox overnight to create 5 pairs of biological replicates. Three pairs of biological replicates were labelled normally (one of which was repeated as a technical replicate using reverse fluors) and 2 pairs of biological replicates were labeled using reverse fluors. The Dosage Experiment reference was used as the reference sample. Less...