Cellular response to oxidative stress at sulfhydryl group receptor sites on the erythrocyte membrane

Ellman's reagent was used to induce an oxidative stimulus on the exofacial membrane sulfhydryl groups of the human erythrocyte. Thiol-disulfide exchange occurring extracellularly was monitored using resonance Raman spectroscopy, and intracellular changes were observed by 1H spin echo nuclear magnetic resonance spectroscopy of the intact cell. The stimulus caused oxidation and depletion of the glutathione pool, which was followed at higher concentrations of Ellman's reagent by a depletion of intracellular ergothioneine levels. Larger changes are induced intracellularly than would be expected from the stoichiometry of the reaction at the exofacial surface. A mechanism is proposed which links exofacial sulfhydryl receptor sites via the transport proteins to spectrin and glutathione. The consequences for the cellular redox balance of an extracellular stimulus of this type are discussed.     

Electrophoretic analysis of endonuclease-generated fragments of k-DNA, of esterase isoenzymes, and of surface proteins as aids for species identification of insect trypanosomatids

In order to verify the applicability of biochemical methods for species identification of Trypanosomatidae, 13 species of monoxenic trypanosomatids plus the heteroxenous Trypanosoma cruzi were comparatively analyzed by three different biochemical methods. Insect trypanosomatids examined were: Crithidia acanthocephali, C. fasciculata (three varieties), C. luciliae luciliae, C. luciliae thermophila, C. deanei, C. oncopelti, Herpetomonas muscarum muscarum, H. megaseliae, H. samuelpessoai, H. mariadeanei, Leptomonas seymouri, L. collosoma, L. samueli, and Blastocrithidia culicis. Also included in the survey were aposymbiotic strains of C. deanei and C. oncopelti. Methods used were: electrophoretic profiling of endonuclease-generated fragments of k-DNA, esterase isoenzymes profiling, and polyacrylamide-gel electrophoresis (SDS-PAGE) of radioiodinated cell surface proteins. Interspecific but not intraspecific differences were detected by all three methods among the 13 monoxenic species examined. Thus, it is concluded that these methods can be successfully used, in addition to classical criteria, for species identification of insect trypanosomatids.