''Amanita sphaerobulbosa'', commonly known as the Asian abrupt-bulbed Lepidella, is a species of
agaric
An agaric () is a type of fungus fruiting body characterized by the presence of a pileus (cap) that is clearly differentiated from the stipe (stalk), with lamellae (gills) on the underside of the pileus. In the UK, agarics are called "mushroom ...
fungus in the family
Amanitaceae
The Amanitaceae is a family of mushroom-forming fungi. ''Amanita'' Pers. is one of the most specious and best-known fungal genera. The family, also commonly called the amanita family, is in order Agaricales, the gilled mushrooms. The family c ...
. First
described by mycologist
Tsuguo Hongo in 1969,
it is found in Southern Asia. The species was formerly consider synonymous with the North American lookalike ''
Amanita abrupta'', but that species has narrower
spores, a persistent
partial veil
In mycology, a partial veil (also called an inner veil, to differentiate it from the "outer", or universal veil) is a temporary structure of tissue found on the fruiting bodies of some basidiomycete fungi, typically agarics. Its role is to isola ...
, and lacks the refractive contents found in the
hyphae and inflated cells of ''A. sphaerobulbosa''.
The
fruit bodies of ''Amanita sphaerobulbosa'' are damaging to the liver; the toxicity is thought to be largely due to a rare
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
. Although not considered as toxic as its infamous relatives the
death cap and the
destroying angel
The name destroying angel applies to several similar, closely related species of deadly all-white mushrooms in the genus ''Amanita''. They are '' Amanita bisporigera'' and '' A. ocreata'' in eastern and western North America, respectively, and '' ...
, ''A. sphaerobulbosa'' is blamed for the deaths of two Japanese women in 1978. Poisoning symptoms included the abrupt appearance of violent vomiting, diarrhea and dehydration after a delay of 10–20 hours.
Habitat and distribution
The mushroom has been collected in
Korea
Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
,
and
Japan.
Toxicity
Ingestion of ''Amanita sphaerobulbosa'' fruit bodies is
toxic to the liver.
Laboratory experiments have shown that mice that ingested ''A. sphaerobulbosa'' mushroom
extracts developed
cholera-like symptoms. A minimum single
lethal dose
In toxicology, the lethal dose (LD) is an indication of the lethal toxicity of a given substance or type of radiation. Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilog ...
of mushroom extract (equivalent to 4.5 grams of
fruiting body
The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cy ...
per kilogram of mouse body weight) caused mice to become prostrate 6 hours after injection; shortly after the mice had diarrhea, then ultimately died between 24 and 48 hours after administration of the extract.
In
Nagano, Japan in 1978, two women died from
mushroom poisoning suspected to be caused by this species.
The symptoms were characterized by the abrupt appearance of violent vomiting, diarrhea and dehydration after a delay of 10–20 hours. Although not as toxic as the
destroying angel
The name destroying angel applies to several similar, closely related species of deadly all-white mushrooms in the genus ''Amanita''. They are '' Amanita bisporigera'' and '' A. ocreata'' in eastern and western North America, respectively, and '' ...
(''A. virosa'') or the
death cap (''A. phalloides''), ''A. sphaerobulbosa'' causes changes in liver function similar to these species. Effects include a decrease in
blood sugar
Glycaemia, also known as blood sugar level, blood sugar concentration, or blood glucose level is the measure of glucose concentrated in the blood of humans or other animals. Approximately 4 grams of glucose, a simple sugar, is present in the blo ...
levels, depletion of stored carbohydrate reserves (liver
glycogen), and an
increase in transaminases.
Biochemistry
Several novel unusual
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
s have been isolated from ''Amanita sphaerobulbosa'', including (2''S'',4''Z'')-2-amino-5-chloro-6-hydroxy-4-hexenoic acid;
D,L-2-amino-4-pentynoic acid (0.257%
w/w); and
L-2-amino-4,5-hexadienoic acid (0.911% w/w). These last two chemicals are suspected to be largely responsible for the toxic effects of the mushroom as they have also been found in ''A. solitaria'' and ''
A. pseudoporphyria''.
The chemical 2-amino-4-pentynoic acid (also known as
propargylglycine
Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid ( carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinog ...
)
inhibits enzymes involved in the
metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...
of the amino acids
methionine and
cystathionine
Cystathionine is an intermediate in the synthesis of cysteine.
Cystathionine is produced by the transsulfuration pathway which converts homocysteine into cystathionine. Cystathionine is then used by the enzymes cystathionine gamma-lyase (CTH), ...
in the liver;
it was also shown to have mild inhibitory effects on
glycogenolysis in rat
hepatocytes
A hepatocyte is a cell of the main parenchymal tissue of the liver. Hepatocytes make up 80% of the liver's mass.
These cells are involved in:
* Protein synthesis
* Protein storage
* Transformation of carbohydrates
* Synthesis of cholesterol, ...
.
See also
*
List of ''Amanita'' species
*
List of deadly fungi
Although many people have a fear of mushroom poisoning by "toadstool
A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denot ...
References
External links
*
{{Taxonbar, from=Q4739884
sphaerobulbosa
Fungi described in 1969
Fungi of Asia
Poisonous fungi