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Han Asard

  • Research interest:My expertise lies in the analysis of redox metabolism and oxidative stress processes, with particular emphasis on plant responses to abiotic stress factors (e.g. temperature, water deficit). We quantitatively analyze multiple oxidative stress components, including, cell level damage (e.g. protein oxidation, lipid peroxidation, membrane leakage), proteins and enzymes (e.g. antioxidant enzymes, glutaredoxin, thioredoxin) and redox metabolites (e.g., ascorbate, H2O2, glutathione). In addition, we analyze plant metabolic responses that are pertinent to stress responses, such as photorespiration, proline metabolism, C-fixation, TCA cycle and primary metabolism. Analyses are standardized and optimized on model plant species, i.e. Zea mays and Arabidopsis thaliana, but tissues from multiple other species, plants and animals, have also been analyzed. Samples are processed in a semi high-throughput protocol, allowing the simultaneous analysis of relatively large numbers of samples. All analyses include assistance in data processing (calculations) and interpretations.
  • Disciplines:Biochemistry and metabolism, Plant biology, Systems biology, Medical biochemistry and metabolism
  • Research techniques:The quantitative analyses related to oxidative stress metabolism that are currently available are:Cell damage / oxidative stress markers::Hydrogen peroxide (H2O2) / lipid peroxidation / membrane integrity / protein carbonylation.Antioxidant and redox metabolites:Anthocyanins / antioxidant capacity / ascorbate (oxidized/reduced) / carotenoids (α/β carotene, lutein, xanthophyll, zeaxanthin) / flavonoids / glutathione (oxidized/reduced) / polyphenols / tocopherols (α, β, γ, σ).Antioxidant enzymes and redox proteins:Ascorbate oxidase (AO) / ascorbate peroxidase (APX) / catalase (CAT) / dehydroascorbate reductase (DHAR) / ferredoxin / glutathione reductase (GR) / glutathione peroxidase (GPX) / glutathione-S transferase (GST) / glutaredoxin / lipoxygenase / monodehydroascorbate reductase (MDHAR) / NADPH oxidase (NOX) / peroxidases (mixed substrates, POX) / peroxiredoxin / phenylalanine ammonialyase (PAL) / superoxide dismutase (SOD) / thioredoxin.Photorespiration:Glycine / glycolate oxidase / hydroxypyruvate reductase / serine.Proline metabolism:Arginase (ARG) / glutamine synthase / NADH-glutamate dehydrogenase (GDH) / ornithine-d-aminotransferase (OAT) / proline / proline dehydrogenase (ProDH) / pyrroline-5-carboxylate reductase (P5CR) / pyrroline-5-carboxylate synthetase (P5CS). The methodologies applied for the quantitative analyses of these enzymes and molecules include spectroscopy, liquid chromatography, GC-MS, electrochemical detection. Most protocols are optimized for semi high-throughput processing, by down-scaling to 96-well microplate measurements.
  • Users of research expertise:The phenomenon of oxidative stress is common to most organisms. Therefore the user of this expertise include all researchers involved with stress responses, in plant or animal tissues.