Adaptive response of Schizosaccharomyces pombe to hydrogen peroxide

Abstract Schizosaccharomyces pombe becomes resistant to killing by high concentration of hydrogen peroxide and other severe stresses including oxidants, high temperature and high concentration of ethanol when pretreated with nonlethal levels of hydrogen peroxide. In the presence of the protein synthesis inhibitor, cycloheximide, during hydrogen peroxide pretreatment, the cell obtained partial resistance to a higher level of hydrogen peroxide. The partial resistance to hydrogen peroxide in the presence of cycloheximide was acquired within 30 min of pretreatment but complete resistance obtained with de novo protein synthesis was not attained before 45 min of pretreatment. During adaptation to hydrogen peroxide, at least 15 polypeptides are induced, as analyzed by two-dimensional gel electrophoresis. Catalase activity is induced eight-fold by treatment with a nonlethal level of hydrogen peroxide.     

High Resolution Proton NMR Spectroscopy of Multiple Sclerosis Lesions

Abstract: Tissue from postmortem multiple sclerosis and normal control brains was extracted with perchloric acid and analysed using proton NMR spectroscopy. The content of N -acetyl-derived groups (the sum of N -acetylaspartate, acetate, and N -acetylaspartylglutamate) was decreased in multiple sclerosis plaques compared with normal control white matter (mean, 4.36 vs. 6.64 µmol/g wet weight). In normal appearing white matter adjacent to plaques a corresponding decrease was seen, with no change in white matter distant from plaques. A decrease in the content of total creatine was observed in multiple sclerosis plaques in comparison with normal control white matter (mean, 4.64 vs. 6.56 µmol/g wet weight), which correlated strongly with the decrease in N -acetyl-derived groups. No changes in other metabolites such as total choline or myo -inositol were seen. The decreases in content of N -acetyl-derived groups are in agreement with observations from in vivo proton NMR spectroscopy in multiple sclerosis patients. The decrease in total creatine is in contrast to most of the observations made in vivo where total creatine is assumed to be unchanged and metabolite levels are often expressed as a total creatine ratio. The use of a total creatine ratio in vivo could lead to an underestimation of reductions in N -acetylaspartate and an apparent increase in other metabolites in the multiple sclerosis lesion.     

Characterization of the pH-mediated solubility of Bacillus thuringiensis var. san diego native delta-endotoxin crystals.

Native crystals of Bacillus thuringiensis var. san diego, a coleopteran-specific delta-endotoxin, were metabolically labelled with [35S]methionine. Specific activity was 82,000 CPM/micrograms (2.44 Ci/mmol). Using a universal buffer formulated with the same ionic strength at every pH, we determined that native crystals dissolve above pH 10 and below pH 4. At the acidic pH, the rate of solubilization was substantially slower than at the alkaline pH. Recrystallization rates for the toxin were similar regardless of solubilization conditions. The banding patterns in denatured polyacrylamide gel electrophoresis were unaffected by solubilization conditions. Toxicity was higher for soluble toxin compared to crystal toxin, but virtually identical for the acidic and alkaline produced solutions. Acid solubilization is significant because of the acidic midgut of susceptible Coleoptera.     

The P2 element of the td intron is dispensable despite its normal role in splicing.

The P2 region of group I introns has been proposed to be involved in the correct positioning of the P1 5'-splice site duplex in the catalytic core (Michel, F., and Westhof, E. (1990) J. Mol. Biol. 216, 585-610). The behavior of delta P2 deletion mutants of the td intron is consistent with this hypothesis. The delta P2 mutants are capable of site-specific hydrolysis, indicating that the conformation of the ribozyme is not grossly altered, but they are incapable of transesterification reactions at the splice sites, as would be predicted if P1 is not appropriately aligned within the catalytic core. Nevertheless, the function of the P2 element can be bypassed in specific pseudorevertants isolated by genetic selection from the delta P2 mutants. These results, together with phylogenetic data, support the existence of alternate strategies to create a functional P1-core interaction.     

TAP1 mutant mice are deficient in antigen presentation, surface class I molecules, and CD4-8+ T cells.

The transporter associated with the antigen processing 1 (TAP1) gene encodes a subunit for a transporter, presumed to be involved in the delivery of peptides across the endoplasmic reticulum membrane to class I molecules. We have generated mice with a disrupted TAP1 gene using embryonic stem cell technology. TAP1-deficient mice are defective in the stable assembly and intracellular transport of class I molecules and consequently show severely reduced levels of surface class I molecules. These properties are strikingly similar to those described for the TAP2 mutant cell line RMA-S. Cells from the TAP1-deficient mice are unable to present cytosolic antigens to class I-restricted cytotoxic T cells. As predicted from the near absence of class I surface expression, TAP1-deficient mice lack CD4-8+ T cells.     

Determination of esterase activity of human and animal serine proteinases using fluorogenic esters of amino acids as substrates]

Two fluorogenic derivatives of amino acids are proposed as substrates for the purpose of enzymatic assay: N-benzyloxycarbonyl-phenylalanine-4-methyl umbelliferyl ester (substrate-1) and tert-butyloxycarbonyl-alanine-4-methyl-umbelliferyl ester (substrate-II). Chymotrypsin-like (hydrolysis of substrate-1), elastase-like (hydrolysis of substrate-II) esterase activity of bovine pancreatic chymotrypsin, activities of cathepsin G and elastase from human, porcine and rat neutrophils and esterase activity of human, porcine and rat serum were assayed. Differences in the level of chymotrypsin-like and elastase-like activities of human, porcine and rat serum were established. Activities of purified elastase and cathepsin G from human and animal neutrophils were shown to have no significant distinctions.