Introduction & Morphology
Kingdom: Fungi
Division: Basidiomycota Class: Agaricomycetes Subclass: Agaricomycetidae Order: Agaricales Family: Amanitaceae Genus: Amanita Species: A. phalloides |
A. phalloides (alternatively Agaricus phalloides, Agaricus bulbosus, or Amanita bulbosa[11]), a basidiomycete, is one of the deadliest mushrooms in the world[11], and accounts for about 50% of all cases of mushroom poisoning on its own[10][14]. The visible fruiting body starts with a small, nearly oval cap, which may grow up towards as high as 16cm in diameter[10]. The cap is convex, but can be only slightly convex (almost flat), is smooth, and may be shiny or metallic even when dry[10]. It varies between green, yellowish, and white, sometimes with a darker center, and has white gills and spores[10]. Each A. phalloides has an annulus around its stalk, remnants of a "partial" veil that protected the spore producing gills during development, and a cup-shaped volva, often partially buried, at the base of the stalk, remnants of a "universal" veil that fully enveloped the developing fruiting body[10].
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A. phalloides form ectomycorrhiza with the roots of oaks[10][11][12][13], and cannot live without their tree-hosts[12]. They originate from Europe, but have invaded all continents besides antartica either by hiking their spores on humans, or due to being necessarily transported with their tree hosts when humans desired the trees to come with them to other continents without dying[12]. Following migration, A. phalloides has shifted hosts, from European aks to Californian live oaks, an incredibly rare event whose mechanism is still under investigation[12]. It is now found in relationships with hazelnuts[10], beechs[11], and native American pines[12].
Toxicity
Physically, death caps resemble puffballs when they are young, and several edible species of mushroom when they are mature, which they even grow side by side with[12]. Many people are poisoned due to this source of confusion, and many who are claim that it was the most delicious mushroom they’ve ever eaten. The toxin, an 8 amino acid long, heat-stable[13] peptide, amanitin, is lethal at about 0.1mg/kg[11][15] of body weight. A fully grown mushroom may contain about 5-8mg of amatoxin[11]. The peptide inhibits RNA polymerase II[10][15] in virtually all eukaryotes[13][15] interfering with transcription and ultimately leading to irreversible kidney and liver damage[11], including hepatic necrosis[15]. Fortunately, the molecule is too large to cross the blood-brain barrier[13]. It is not destroyed by cooking or freezing[15] or drying.
Interestingly, four species of the genus Drosphilia have been found laying their eggs in the gills of developing death caps. It turns out that the advantage of the amanitin killing the nematodes that reproduce in the stomachs of fruit flies overcomes the disadvantage of the parental deaths from the toxin[13].
Interestingly, four species of the genus Drosphilia have been found laying their eggs in the gills of developing death caps. It turns out that the advantage of the amanitin killing the nematodes that reproduce in the stomachs of fruit flies overcomes the disadvantage of the parental deaths from the toxin[13].
Brief overview of reproductive structures
References
[10]French, L., Hendrickson, R. G., & Horowitz, B. (2011). Amanita phalloides poisoning. Clinical Toxicology (15563650), 49(2), 128-129. doi:10.3109/15563650.2011.557663
[11]Křenová, M. M., Pelclová, D. D., & Navrátil, T. T. (2007). Survey of Amanita phalloides poisoning: clinical findings and follow-up evaluation. Human & Experimental Toxicology, 26(12), 955-961. doi:10.1177/0960327107085832
[12]http://www.slate.com/articles/health_and_science/medical_examiner/2014/02/most_dangerous_mushroom_death_cap_is_spreading_but_poisoning_can_be_treated.html
[13]http://cnpsslo.org/2013/03/2145/
[14]http://www.huh.harvard.edu/libraries/Amanita_exhibit/Amanita_poisoning.htm
[15]Mas, A. (2005). Mushrooms, amatoxins and the liver. Journal Of Hepatology, 42(2), 166-169.
[11]Křenová, M. M., Pelclová, D. D., & Navrátil, T. T. (2007). Survey of Amanita phalloides poisoning: clinical findings and follow-up evaluation. Human & Experimental Toxicology, 26(12), 955-961. doi:10.1177/0960327107085832
[12]http://www.slate.com/articles/health_and_science/medical_examiner/2014/02/most_dangerous_mushroom_death_cap_is_spreading_but_poisoning_can_be_treated.html
[13]http://cnpsslo.org/2013/03/2145/
[14]http://www.huh.harvard.edu/libraries/Amanita_exhibit/Amanita_poisoning.htm
[15]Mas, A. (2005). Mushrooms, amatoxins and the liver. Journal Of Hepatology, 42(2), 166-169.