The Functions of Mediator in Candida albicans Support a Role in Shaping Species-Specific Gene Expression

The Mediator complex is an essential co-regulator of RNA polymerase II that is conserved throughout eukaryotes. Here we present the first study of Mediator in the pathogenic fungus Candida albicans. We focused on the Middle domain subunit Med31, the Head domain subunit Med20, and Srb9/Med13 from the Kinase domain. The C. albicans Mediator shares some roles with model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, such as functions in the response to certain stresses and the role of Med31 in the expression of genes regulated by the activator Ace2. The C. albicans Mediator also has additional roles in the transcription of genes associated with virulence, for example genes related to morphogenesis and gene families enriched in pathogens, such as the ALS adhesins. Consistently, Med31, Med20, and Srb9/Med13 contribute to key virulence attributes of C. albicans, filamentation, and biofilm formation; and ALS1 is a biologically relevant target of Med31 for development of biofilms. Furthermore, Med31 affects virulence of C. albicans in the worm infection model. We present evidence that the roles of Med31 and Srb9/Med13 in the expression of the genes encoding cell wall adhesins are different between S. cerevisiae and C. albicans: they are repressors of the FLO genes in S. cerevisiae and are activators of the ALS genes in C. albicans. This suggests that Mediator subunits regulate adhesion in a distinct manner between these two distantly related fungal species

Sphaerotilus natans Isolated from Activated Sludge and Its Production of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Sphaerotilus natans is a sheathed bacterium existing in the activated sludge of wastewater treatment plants. It is one of the filamentous bacteria causing the bulking and foaming difficulties of activated sludge. Isolating the strain and culturing it in an axenic environment could not only provide the metabolic knowledge of the strains that would be useful in the development of wastewater treatment methods, but also could enable us to gain an understanding of the mechanism by which poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (poly[3-HB-co-3-HV]) is produced by this strain. This article reports the screening and isolation of the strain from the activated sludge using the Nile blue staining method together with Fourier transform infrared analysis. We investigated the ability of the selected strain to produce poly(3-HB-co-3-HV) cop01ymer using glucose and peptone, or by adding valeric acid or sodium propionate as precursor. Proper precursor feeding could dramatically enhance its 3HV content in the copolymer P(3HB-co-3HV). By controlling the different feeding times in fed-batch fermentation, different desired copolymers were obtained with 15, 40, and 70% 3HV mole fraction of the copolymer. Polymer properties were analyzed by gas chromatography, differential scanning calorimetry, thermo-gravimetry, and nuclear magnetic resonance analysis.Department of Applied Biology and Chemical Technolog

Glucan-Based Macrophage Stimulators

Sepsis and sepsis syndrome are significant causes of morbidity and mortality in critically ill surgical patients. Despite technological and therapeutic advances in critical care, sepsis continues to be a pivotal factor in 20 to 50% of deaths in surgical intensive care units. It is clear that alternative approaches to the prevention and/or treatment of sepsis must be found. Preclinical data indicate that macrophage activation with ( I -\u3e3)-D-gIucans will ameliorate sequelae associated with Gram-negative septicaemia. We and others have translated these preclinical observations to the clinical setting and have shown that macrophage activation with (l-\u3e3)-D-gIucans will significantly reduce septic morbidity and mortality in trauma and/or high-risk surgical patients. The precise mechanism(s) by which ( I-\u3e3)-D-glucans prevent or ameliorate infections have not been fully elucidated. However, recent data suggest the anti-infective efficacy of (l-\u3e3)-D-gIucans is attributable, in part, to macrophage activation induced by binding of (l-\u3e3)-D-gIucan to a specific receptor followed by modulation of macrophage pro-inflammatory cytokine expression. This article reviews the anti-infective potential of ( l-3)-D-glucans in the prevention of sepsis and septic sequelae