title: Visual expression analysis of the responses of the alternative oxidase gene (aox1) to heat shock, oxidative, and osmotic stresses in conidia of citric acid-producing Aspergillus niger.
abstract: The citric acid-producing filamentous fungus Aspergillus niger WU-2223L shows cyanide-insensitive respiration catalyzed by alternative oxidase in addition to the cytochrome pathway. Sequence analysis of the 5' flanking region of the alternative oxidase gene (aox1) revealed a potential heat shock element (HSE) and a stress response element (STRE). We have previously confirmed aox1 expression in conidia. In this study, to confirm whether the upstream region of aox1 responds to various stresses, we used a visual expression analysis system for single-cell conidia of the A. niger strain AOXEGFP-1. This strain harbored a fusion gene comprising aox1 and egfp, which encodes the enhanced green fluorescent protein (EGFP). The fluorescence intensity of EGFP increased in conidia of A. niger AOXEGFP-1 that were subjected to heat shock at 35-45 °C, oxidative stress by exposure to 5mM paraquat or 1 mM t-butylhydroperoxide, or osmotic stresses by exposure to 0.5 M KCl or 1.0 M mannitol. These results indicate that the putative HSE and STRE in the upstream region of aox1 directly or indirectly respond to heat shock, oxidative, and osmotic stresses.
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169–8555, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Honda
authors.forename: Takasumi
authors.initials: T
authors.lastname: Hattori
authors.forename: Kohtaro
authors.initials: K
authors.lastname: Kirimura
mesh_terms: D001234:Aspergillus niger / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D019343:Citric Acid / Q000378:metabolism; D004234:Diuretics, Osmotic / Q000494:pharmacology; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018869:Heat-Shock Response; D006540:Herbicides / Q000494:pharmacology; D008353:Mannitol / Q000494:pharmacology; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D009995:Osmosis; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010269:Paraquat / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D013172:Spores, Fungal / Q000201:enzymology / Q000502:physiology; D013312:Stress, Physiological; D020122:tert-Butylhydroperoxide / Q000494:pharmacology; D000099188:Alternative Oxidase
chemical_list: D019343:Citric Acid; D004234:Diuretics, Osmotic; D049452:Green Fluorescent Proteins; D006540:Herbicides; D008353:Mannitol; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010269:Paraquat; D010940:Plant Proteins; D011189:Potassium Chloride; D020122:tert-Butylhydroperoxide; D000099188:Alternative Oxidase; C485184:enhanced green fluorescent protein