Shinjiro Muraoka

Gunma University, Maebashi, Gunma, Japan

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Publications (3)5.55 Total impact

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    ABSTRACT: BACKGROUND: Although some Japanese Galerina species poisonings manifest as gastrointestinal symptoms followed by late-onset hepatorenal failure (phalloides syndrome), the toxin responsible for this has not been determined. CASE REPORT: We report a 6-year-old boy who developed characteristic cholera-like diarrhea and late-onset severe hepatic deterioration after eating mushrooms, later identified as a Galerina species, most likely Galerina fasciculata. A residual mushroom revealed alpha-amanitin. This account is the first known reported case of poisoning by Japanese Galerina species where an amatoxin was demonstrated to be responsible for the toxicity.
    No preview · Article · Feb 2001 · Journal of toxicology. Clinical toxicology
  • Shinjiro Muraoka · Takao Shinozawa
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    ABSTRACT: Practical production of amanitins was attempted by fermentation using a basidiomycete, Galerina fasciculata GF-060. In liquid fermentation, intracellular alpha- and gamma-amanitins were the main products, while alpha- and beta-amanitins accumulated in solid cultured mycelia. The production of amanitins in liquid fermentation was strongly affected by the amount of the remaining carbon sources (particularly glucose and sucrose). In batch cultivation, the productivity of alpha-amanitin was 1.58 mg/l. To improve the productivity, replacement cultivation using glucose-free medium was attempted. As a result, the maximum production of alpha-amanitin reached 5.02 mg/l. These conditions (fermentation style and glucose starvation) are effective for the production of all the known types of amanitins.
    No preview · Article · Feb 2000 · Journal of Bioscience and Bioengineering
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    S Muraoka · N Fukamachi · K Mizumoto · T Shinozawa
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    ABSTRACT: More than 600 strains of wood-rotting fungi were screened for the detection of amanitins. Three strains of Galerina fasciculata and 18 strains of Galerina helvoliceps contained amanitins. These strains contained mainly alpha- and beta-amanitins in the native fruit bodies, while alpha- and gamma-amanitins were found in liquid-cultured mycelia. Purified amanitins were confirmed by their chromatographic profiles, spectra (UV, Fourier transform infrared, and atmospheric ionization mass), cytotoxicity for mammalian cell lines (3T3 and SiHa), and inhibitory effects on RNA polymerase II. The results revealed that the purified amanitin fractions from these species are identical to authentic amanitins and suggest that these two species must be handled as poisonous mushrooms.
    Preview · Article · Oct 1999 · Applied and Environmental Microbiology