albicans, and as a consequence, reduce biofilm formation. However, our results suggest that the compound in serum that inhibits C. albicans biofilm formation is not proteinaceous. Abraham et al.[15] found that a low molecular weight component of human serum inhibits biofilm formation in Staphylococcus aureus, and the component was protease-resistant and heat stable. We conclude here that human serum may also contain non-protein component(s) that can inhibit the adhesion and biofilm formation Talazoparib in vivo of fungi and bacteria. To confirm this hypothesis, future studies are needed to identify this component of human serum. In this study, planktonic growth of C. albicans was not inhibited by human serum,

indicating that inhibition of biofilm formation GDC-0449 manufacturer was not due solely to growth inhibition. Biofilm formation of C. albicans, a process that depends upon both cell-cell and cell-substrate adherence, is controlled by a tightly woven network of genes [10]. Among this gene network, BCR1 is one of the best-characterized biofilm regulators [11–13, 29]. Through its adhesin targets ALS1, ALS3, HWP1 and ECE1, BCR1 mediates cell-substrate and cell-cell interactions in biofilms [30, 31]. In this study, at the adhesion stage of biofilm formation (60 min, 90 min), the

expression of BCR1 went from less than to significantly higher than that of the control group. This may be due to the promoting effect of serum on hypha growth, as BCR1 RNA accumulation depends on the hyphal developmental activator TEC1[32]. ALS1 and ALS3 are members of the agglutinin-like sequence (ALS) gene family that encodes cell-wall glycoproteins [33]. Most Als proteins have adhesin functions [34, 35]. Mutational analysis indicates

that strains lacking all functional ALS1 and ALS3 alleles (als1Δ/als1Δ als3Δ/als3Δ) failed to produce any detectable adherent cells in biofilm models both in vivo and in vitro[30], or in actual biofilm formation. The als1Δ/als1Δ mutants produced substantial biofilms, but the biofilms often sloughed Y-27632 2HCl off the substrate, while the als3Δ/als3Δ mutant only produced scant, disorganized biofilms on catheter material in vitro[12]. Our data on transcript analysis showed that the expression of ALS1 and ALS3 were reduced at different time points in the biofilm adhesion stage. Therefore, we supposed that the anti-adhesion effect of human serum might occur via inhibition of the expression of ALS1 and ALS3, and therefore affect biofilm formation. Previous studies have shown that a bcr1Δ/ bcr1Δ mutant, which has reduced expression of ALS1, ALS3, and other adhesins, has defective biofilm formation in both an in vitro and in vivo catheter model [12]. In this study, at 90 min of growth, the change in the levels of BCR1 level was different from ALS1 and ALS3, indicating that ALS1 and ALS3 are also affected by other factors [8, 36]. Interestingly, human serum promotes the expression of HWP1 and ECE1. HWP1 is a well-characterized BI 2536 price hypha-specific gene that can mediate C.