Home About us Contact
|
Home About us Contact | ||
|
|
||
Hydrogen Peroxide Generation (hydrogen + peroxide_generation)
Selected AbstractsStudies on the mechanism of resistance to Bipolaris sorokiniana in the barley lesion mimic mutant bst1MOLECULAR PLANT PATHOLOGY, Issue 5 2009MATTIAS PERSSON SUMMARY The Bipolaris sorokiniana tolerant 1 (bst1) barley mutant is derived from fast neutron-irradiated seeds of wild-type Bowman(Rph3). The induced mutation was genetically localized to a position on chromosome 5HL distal to the centromere using amplified fragment length polymorphism markers. In addition, the defence responses and related gene expression in the bst1 mutant after fungal challenge were compared with those occurring in wild-type plants. Hydrogen peroxide generation, determined by 3,3-diaminobenzidine staining, revealed a clearly reduced level of bst1, compared with the wild-type, during the entire experimental time: 8,120 h post-inoculation (hpi). At 48 hpi, the wild-type samples displayed twice as much fungal mass and three times greater H2O2 production than bst1. At the same time, staining of B. sorokiniana showed less fungal growth in the spontaneous lesions of bst1 compared with the wild-type. Monitoring of defence-related genes at 48 hpi demonstrated strong expression of PR-1a, PR-2, PR-5 and PR-10 in bst1. A gene coding for a unique oxidoreductase enzyme, designated as HCP1, was expressed at much higher levels in inoculated leaves of the bst1 mutant than in those of the wild-type plant. Taken together, the results suggest that the defence to B. sorokiniana largely relies on salicylic acid-responsive pathogenesis-related (PR) genes, as well as selected reactive oxygen species and unknown HCP1 -associated factors. [source] ETHANOL-INDUCED SUPEROXIDE RADICALS IN FETAL CORTICAL NEURONS: CELLULAR ROS NETWORKALCOHOLISM, Issue 2008Amina E Jamali Alcohol exposure to the developing brain compromises both neurons and glial functions. While neurons are considered the primary targets, microglia may play a neurotoxic role in this process. Previous studies demonstrated that neuron death is due to oxidative stress and mitochondrially mediated (Intrinsic). These studies showed a rapid increase (within minutes) in reactive oxygen species (ROS). Due to the diffusive nature of ethanol and multiple sources of free radicals, we sought to determine the primary source of superoxide targeted by ethanol. Confocal studies of neurons suggest that the superoxide radicals may originate from the mitochondria. Using whole neurons in a luminol-based chemiluminescence assay (Diogenes) we detected superoxide radicals in the extracellular mileu. We observed a two-three fold transient increase in the steady state generation of superoxide radicals between 20 minutes to one hour of ethanol exposure (4mg/ml). However, the presence of Rotenone (mitochondrial complex I inhibitor) and DPI (an inhibitor of all flavinoids) blocked the release of these superoxide radicals. Interestingly, cortical microglia treated identically with ethanol, showed a greater than five fold increase in superoxide generation with a maximum at one hour. Moreover, since ethanol is known to induce hydrogen peroxide generation, it was used as a mimetic. Hydrogen peroxide also induced the production of superoxide different time kinetics. Thus, together these data demonstrate that ethanol induces the steady state production of superoxide radicals in the extracellular mileu in a mitochondrial dependent manner. Since NOX2 an NADPH oxidase is expressed in neurons, it is a potential candidate for the secondary sites of superoxide generation. The ROS network between mitochondria and the plasma membrane highlights new therapeutical targets to counter ethanol toxicity. [source] ,-MSH tripeptide analogs activate the melanocortin 1 receptor and reduce UV-induced DNA damage in human melanocytesPIGMENT CELL & MELANOMA RESEARCH, Issue 5 2009Zalfa A. Abdel-Malek Summary One skin cancer prevention strategy that we are developing is based on synthesizing and testing melanocortin analogs that reduce and repair DNA damage resulting from exposure to solar ultraviolet (UV) radiation, in addition to stimulating pigmentation. Previously, we reported the effects of tetrapeptide analogs of ,-melanocortin (,-MSH) that were more potent and stable than the physiological ,-MSH, and mimicked its photoprotective effects against UV-induced DNA damage in human melanocytes. Here, we report on a panel of tripeptide analogs consisting of a modified ,-MSH core His6 - d -Phe7 -Arg8, which contained different N -capping groups, C-terminal modifications, or arginine mimics. The most potent tripeptides in activating cAMP formation and tyrosinase of human melanocytes were three analogs with C-terminal modifications. The most effective C-terminal tripeptide mimicked ,-MSH in reducing hydrogen peroxide generation and enhancing nucleotide excision repair following UV irradiation. The effects of these three analogs required functional MC1R, as they were absent in human melanocytes that expressed non-functional receptor. These results demonstrate activation of the MC1R by tripeptide melanocortin analogs. Designing small analogs for topical delivery should prove practical and efficacious for skin cancer prevention. [source] Using paraquat to generate anion free radicals and hydrogen peroxide in in vitro: Antioxidant effect of vitamin EBIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 2 2010A procedure to teach theoretical, experimental principles of reactive oxygen species biochemistry Abstract The theoretical basis of reactive oxygen species and their impact on health issues are relatively easy to understand by biomedical students. The detection of reactive oxygen species requires expensive equipment, the procedures are time consuming and costly, and the results are hard to interpret. Moreover, cause-and-effect relationships in the living system are not so evident. In this report, we adapted a two-step procedure to detect anion superoxide radicals and hydrogen peroxide generation in lymphocytes exposed to paraquat by using nitroblue tetrazolium salt and dihydrorhodamine, respectively. Also, a two-step assay was performed to evaluate lymphocyte viability and nuclei morphologic changes on paraquat exposure for 1 and 24 hours incubation time by using trypan blue exclusion assay and acridine orange/ethidium bromide staining technique, respectively. Vitamin E was used as antioxidant to inhibit the deleterious effects of paraquat on cells. Students learned how to (i) design and perform experiments in the laboratory, (ii) read critical scientific literature, and (iii) discuss and contrast relevant information about reactive oxygen species as causative agents of cell death phenomenon. [source] | ||||||||||