MEDICAL MYCOLOGY

Dr Tadayo Hashimoto M.D.
Professor
Department of Microbiology & Immunology

7. All of the following statements are true EXCEPT that

aflatoxins are produced by Aspergillus flavus and have been implicated in human liver cancer
amatoxins and phallotoxins are produced by poisonous mushrooms
amatoxins and phallotoxins interfere with messenger RNA functions in the liver
mycotoxicosis can be treated with sera containing specific antitoxins
heating has essentially no effect on reducing the toxicity of mycotoxins

(D) Some fungi generate substances with direct toxicity for humans and animals. Such toxins are secondary metabolic products of fungi. These toxins are collectively called mycotoxins. Mycotoxicoses (mycetismus) occur after their inadvertent ingestion. Heating of mycotoxins has little effect on reducing the toxicity. The amatoxins and phallotoxins represent two important families of mycotoxins produced by poisonous mushrooms such as Amanita. The liver is a target organ for these toxins. Alpha amanitin (amatoxin) binds to a subunit of RNA polymerase II and consequently interferes with messenger RNA and protein synthesis. Phalloidin binds to and stabilizes F actin. Treatment of mushroom poisoning is largely supportive as specific antidotes are not available. Aflatoxins are tumorigenic for animals. (Joklik et al, pp. 1082-1083)

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