By doing so, we found that ALS1, ALS2 and ALS5 were overexpressed in all model systems, but their fold upregulations were more pronounced in both in vitro models and in the in vivo model, compared to the RHE model.

Using mutant strains, it was already demonstrated that Als1p and Als2p are involved in biofilm formation on abiotic surfaces [29, 34]. Furthermore, ALS4 was highly upregulated in the two in vitro models, and was extremely overexpressed in the RHE and in vivo models. However, deletion of ALS4 did not significantly reduce biofilm formation on silicone and neither resulted in reduced biomass on RHE, but it is likely that Als2p compensates for the loss of ALS4 [34]. Our data clearly show high expression levels for ALS4 in biofilms grown on mucosal surfaces as well as on abiotic surfaces in vitro and in vivo, suggesting selleck chemicals a role for Als4p in C. albicans Alectinib molecular weight biofilms. For ALS6 and ALS9, on the other hand, model-dependent up- and downregulations were observed. ALS6 was not overexpressed in the RHE model, which is not surprising as Als6p reduces adhesion of the fungus to buccal epithelial cells [35]. In both in vitro models and in the in vivo model, on the other hand, we observed an upregulation of ALS6. Using RT-PCR, it was previously shown that ALS6 was weakly expressed in biofilms grown on silicone [21]. However, using real-time PCR, we detected low Ct values (i.e. high

absolute mRNA levels) for ALS6 (data not shown). Furthermore, ALS9 is downregulated in the RHE model, in the MTP and in the vivo model, whereas this

gene is slightly upregulated under flow conditions in the CDC reactor. It is possible that shear stress generated in the CDC reactor induces the expression of ALS9, although further research is needed to confirm this hypothesis. We also studied the expression of ALS3 and HWP1, two genes that encode hyphae-specific adhesins [36, 37]. Their expression levels were higher in the CDC reactor than in the MTP, and the percentage of filaments was also higher in biofilms grown in the CDC reactor. Hyphae are known for their increased adhesive properties [13], and presumably shear stress in the CDC reactor triggers the fungus to form more filaments, which this website in turn express more ALS3 and HWP1. We also found that the percentage of filaments gradually decreased during biofilm formation in both in vitro models. It is known that contact-sensing induces filamentation in C. albicans [38], and therefore it is likely that initial contact of the fungus with the silicone results in filamentation. This could explain why young biofilms contain more filaments than mature ones in both in vitro models. Furthermore, ALS3 and HWP1 were highly upregulated in biofilms grown in the RHE model, and we found an increase in the percentage of filaments during biofilm formation in this model system. In order to grow in the RHE model, C.