Kinetics and mechanism of protection of adenine from sulphate radical anion by caffeic acid under anoxic conditions

The rates of photo-oxidation of adenine in the presence of peroxydisulphate (PDS) have been determined by measuring the absorbance of adenine at 260.5 nm spectrophotometrically. The rates and the quantum yields (phi) of oxidation of adenine by sulphate radical anion (SO4(-)) have been determined in the presence of different concentrations of caffeic acid. Increase in the concentration of caffeic acid is found to decrease the rate of oxidation of adenine suggesting that caffeic acid acts as an efficient scavenger of SO4(-) and protects adenine from it; SO4(-) competes for adenine as well as for caffeic acid. From competition kinetics, the rate constant of SO4(-) with caffeic acid has been calculated to be 1.24 +/- 0.2 x 10(10) mol(-1)dm(3)s(-1). The quantum yields of photo-oxidation of adenine have been calculated from the rates of oxidation of adenine and the light intensity absorbed by PDS at 254 nm, the wavelength at which PDS is activated to SO4' -. The results of experimentally determined quantum yields (phi exptl) and the quantum yields calculated (phi cl) by assuming that caffeic acid acts only as a scavenger of SO4(-) radicals show that phi exptl values are lower than phi cl values. The phi prime values, which are experimentally found quantum yield values at each caffeic acid concentration and corrected for SO4(-) scavenging by caffeic acid, are also found to be greater than phi exptI values. These observations suggest that the adenine radicals are repaired by caffeic acid, in addition to scavenging of sulphate radical anions.     

The extracellular loops of Smoothened play a regulatory role in control of Hedgehog pathway activation

The Hedgehog (Hh) signaling pathway plays an instructional role during development, and is frequently activated in cancer. Ligand-induced pathway activation requires signaling by the transmembrane protein Smoothened (Smo), a member of the G-protein-coupled receptor (GPCR) superfamily. The extracellular (EC) loops of canonical GPCRs harbor cysteine residues that engage in disulfide bonds, affecting active and inactive signaling states through regulating receptor conformation, dimerization and/or ligand binding. Although a functional importance for cysteines localized to the N-terminal extracellular cysteine-rich domain has been described, a functional role for a set of conserved cysteines in the EC loops of Smo has not yet been established. In this study, we mutated each of the conserved EC cysteines, and tested for effects on Hh signal transduction. Cysteine mutagenesis reveals that previously uncharacterized functional roles exist for Smo EC1 and EC2. We provide in vitro and in vivo evidence that EC1 cysteine mutation induces significant Hh-independent Smo signaling, triggering a level of pathway activation similar to that of a maximal Hh response in Drosophila and mammalian systems. Furthermore, we show that a single amino acid change in EC2 attenuates Hh-induced Smo signaling, whereas deletion of the central region of EC2 renders Smo fully active, suggesting that the conformation of EC2 is crucial for regulated Smo activity. Taken together, these findings are consistent with loop cysteines engaging in disulfide bonds that facilitate a Smo conformation that is silent in the absence of Hh, but can transition to a fully active state in response to ligand.     

Spectroscopic investigations of Er(3+) :CdO-Bi(2) O(3) -B(2) O(3) glasses

This article reports on the optical properties of Er³⁺ ions doped CdO–Bi₂O₃–B₂O₃ (CdBiB) glasses. The materials were characterized by optical absorption and emission spectra. By using Judd–Ofelt theory, the intensity parameters Ω_λ (λ = 2, 4, 6) and also oscillatory strengths were calculated from the absorption spectra. The results were used to compute the radiative properties of Er³⁺:CdBiB glasses. The concentration quenching and energy transfer from Yb³⁺–Er³⁺ were explained. The stimulated emission cross‐section, full width at half maximum (FWHM) and FWHM × values are also calculated for all the Er³⁺:CdBiB glasses. Copyright © 2011 John Wiley & Sons, Ltd.     

Natural pathology of the Baboon (Papio spp.)

Background Baboons are useful animal models for biomedical research, but the natural pathology of the baboon is not as well defined as other non‐human primates. Methods A computer search for all morphologic diagnoses from baboon necropsies at the Southwest National Primate Research Center was performed and included all the natural deaths and animals euthanized for natural causes. Results A total of 10,883 macroscopic or microscopic morphologic diagnoses in 4297 baboons were documented and are presented by total incidence, relative incidence by sex and age‐group, and mean age of occurrence. The most common diagnoses in descending order of occurrence were hemorrhage, stillborn, amyloidosis, colitis, spondylosis, and pneumonia. The systems with the most diagnoses were the digestive, urogenital, musculoskeletal, and respiratory. Conclusion This extensive evaluation of the natural pathology of the baboon should be an invaluable biomedical research resource.     

Ferredoxin- and Nicotinamide Adenine Dinucleotide-Dependent H2 Production from Ethanol and Formate in Extracts of S Organism Isolated from “Methanobacillus omelianskii”

S organism ferments ethanol to acetate and H(2) but grows poorly on ethanol unless the partial pressure of H(2) is kept low, as when it is grown in combination with an H(2)-utilizing methanogenic bacterium. The present study shows that S organism contains an alcohol dehydrogenase and a formate dehydrogenase, both of which require nicotinamide adenine dinucleotide (NAD) for activity. Hydrogen is evolved from NADH generated by these activities via a ferredoxin-dependent oxidation of NADH to NAD and H(2). NADH:NADP oxido-reductase activity was also demonstrated. The relationship of these activities to the growth of S organism is discussed.     

Characterization of glucose oxidase-negative mutants of a lignin degrading basidiomycete Phanerochaete chrysosporium

The isolation and characterization of glucose oxidase-negative (gox ^-) mutants of Phanerochaete chrysosporium, is described. These mutants are deficient not only in their ability to produce hydrogen peroxide (H₂O₂) but also in lignin degradation (2-¹⁴C-synthetic lignin¹⁴CO₂), ligninase and peroxidase activities, decolorization of the dye poly-R 481, and production of ethylene from -oxo--methylthiobutyric acid (KTBA). The gox ^- mutants retained, albeit at a lower level, the capacity to produce veratryl alcohol, a typical secondary metabolite, and produced conidia at a level comparable to that of the wild type. The addition of ligninase and/or glucose oxidase to a gox ^- mutant (GOX-10) did not enhance its capacity to degrade lignin. The Gox⁺ revertant strains regained glucose oxidase activity, the ability to degrade lignin, as well as the other characteristics that were missing in the gox ^- mutants. The results suggest that the genetic lesion in these mutants affects the regulation of a set of secondary metabolic characteristics.Abbreviations Gox glucose oxidase - KTBA -oxo--methylthiobutyric acid Journal article no. 11740 from the Michigan Agricultural Experiment Station     

Optimized Batch Fermentation of Cheese Whey-Supplemented Feedlot Waste Filtrate to Produce a Nitrogen-Rich Feed Supplement for Ruminants

A simple and reliable method is described which allows determination of virus inactivation rates during sludge treatment processes in situ. Bacteriophage f2 was adsorbed onto an electropositive membrane filter which was then sandwiched between two polycarbonate membranes with pores smaller than the virus diameter. The resulting sandwich was fixed in an open filter holder, and several such devices were connected before being exposed in sludge-digesting tanks. The device described prevented uncontrolled virus escape, but allowed direct contact of the various inactivating or stabilizing substances present in the environment tested with the virus adsorbed to the carrier membrane. After exposure to an environment, the surviving fraction of virus was eluted from the inner filter and determined by plaque counting. By using polycarbonate membranes without pores for sandwiching, the influence of temperature alone on virus inactivation could be measured. Thermophilic fermentation at 60 degrees C and at 65 kPa pressure led to a bacteriophage f2 titer reduction of 3.5 log10 units per h, whereas during thermophilic digestion at 54.5 degrees C titers decreased 1.2 log10 units per h. During mesophilic digestion an inactivation rate of only 0.04 log10 units per h was observed. Under these latter conditions, temperature had only a minor effect (19%) on virus inactivation, whereas at 54.5 degrees C during thermophilic digestion heat accounted for 32% of the total inactivation, and during thermophilic fermentation at 60 degrees C temperature and pressure were 100% responsible for virus denaturation.