In vivo and in vitro anaerobic mating in Candida albicans

Candida albicans cells of opposite mating types are thought to conjugate during infection in mammalian hosts, but paradoxically, the mating-competent opaque state is not stable at mammalian body temperatures. We found that anaerobic conditions stabilize the opaque state at 37 degrees C, block production of farnesol, and permit in vitro mating at 37 degrees C at efficiencies of up to 84%. Aerobically, farnesol prevents mating because it kills the opaque cells necessary for mating, and as a corollary, farnesol production is turned off in opaque cells. These in vitro observations suggest that naturally anaerobic sites, such as the efficiently colonized gastrointestinal (GI) tract, could serve as niches for C. albicans mating. In a direct test of mating in the mouse GI tract, prototrophic cells were obtained from auxotrophic parent cells, confirming that mating will occur in this organ. These cells were true mating products because they were tetraploid, mononuclear, and prototrophic, and they contained the heterologous hisG marker from one of the parental strains.     

Kinetics of hydrogen peroxide decomposition by catalase: hydroxylic solvent effects

The effect of water–alcohol (methanol, ethanol, propan-1-ol, propan-2-ol, ethane-1,2-diol and propane-1,2,3-triol) binary mixtures on the kinetics of hydrogen peroxide decomposition in the presence of bovine liver catalase is investigated. In all solvents, the activity of catalase is smaller than in water. The results are discussed on the basis of a simple kinetic model. The kinetic constants for product formation through enzyme–substrate complex decomposition and for inactivation of catalase are estimated. The organic solvents are characterized by several physical properties: dielectric constant (D), hydrophobicity (log P), concentration of hydroxyl groups ([OH]), polarizability (α), Kamlet-Taft parameter (β) and Kosower parameter (Z). The relationships between the initial rate, kinetic constants and medium properties are analyzed by linear and multiple linear regression.     

Biological Effects Induced by 68Ga-Conjugated Peptides in Human and Rodent Tumor Cell Lines

International Journal of Peptide Research and Therapeutics - Positron emission tomography (PET) with 68Ga-labeled peptides is a promising option in the imaging of tumors expressing peptide-binding...     

Chiral superstructures from homochiral Zn2+, Co2+, Fe2+‐2,6‐bis (aryl ethylimine)pyridine complexes

We report the hierarchical supramolecular organization of metallosupramolecular homochiral complexes 1 ‐Λ‐(S,S,S,S)‐M²⁺/ 1 ‐?‐(R,R,R,R)‐M²⁺ and 2 ‐ Λ‐(S,S,S,S)‐M²⁺/ 2 ‐?‐ (R,R,R,R)‐M²⁺ of M²⁺ = Co²⁺, Fe²⁺, Zn²⁺ metal ions with chiral pseudo‐terpyridine‐type ligands: 1‐ (S,S) or 1‐ (R,R) = 2,6‐bis (naphthyl ethylimine)pyridine and 2‐ (S,S) or 2‐ (R,R) = 2,6‐bis (phenyl‐ethylimine)pyridine. Circular dichroism measurements in solution were used to confirm the enantiomeric nature of all twelve complexes. For crystal structures of 1 ‐ Λ‐ (S,S,S,S)‐M²⁺ or 1 ‐?‐ (R,R,R,R)‐M²⁺ complexes, absolute configurations {? (or P), Λ (or M)} were confirmed by refinement of the Flack parameter x: ?0.007 ≤ x ≤ 0.11 for the single crystals of 1 ‐Λ‐(S,S,S,S)‐M²⁺/ 1 ‐?‐ (R,R,R,R)‐M²⁺, 2 ‐ Λ‐ (S,S,S,S)‐Fe²⁺, and 2 ‐?‐ (R,R,R,R)‐Co²⁺.