Pleurocybella
Encyclopedia
Pleurocybella is a genus
of fungus
in the Marasmiaceae
family. The genus is monotypic
, containing the single species Pleurocybella porrigens, widespread in temperate
forests of the Northern Hemisphere
. P. porrigens, known as the angel wing, is a white-rot wood-decay fungus
on conifer wood, particularly hemlock (genus Tsuga
). The flesh is thin and fragile compared to the oyster mushrooms (Pleurotus
ssp.).
Pleurocybella porrigens has historically been generally regarded as edible
but this has been brought in to question by recent deaths apparently associated with P. porrigens consumption.
Synonyms for Pleurocybella porrigens include Pleurotus
porrigens, Phyllotus porrigens, Dendrosarcus porrigens, Pleurotellus porrigens, and Nothopanus
porrigens.
disorders.
The first incident occurred in September and October 2004 across nine prefectures in Japan, and involved the sickening of 59 people and the eventual death of 17. Most of those who died had pre-existing liver problems, and the average age of those effected was 70. Death occurred between 13 and 29 days after the onset of symptoms, and the onset of symptoms occurred at most three weeks after consumption of P. porrigens.
The second incident occurred in 2009, when a 65 year old man who had been on hemodialysis died from acute encephalopathy after eating P. porrigens.
The mechanism of action for the toxicity of P. porrigens has not been definitively established, but several possibilities have been suggested. It has been demonstrated that P. porrigens contains an unusual unstable amino acid
which is toxic to the brain cells of rats in cell culture studies, but it has not yet been possible to definitively determine that this was the cause of the fatal encephalopathies. Other mechanisms have been suggested for P. porrigens apparent toxicity, including the possibility that cyanide levels in P. porrigens may be high enough to be toxic.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of fungus
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
in the Marasmiaceae
Marasmiaceae
The Marasmiaceae are a family of basidiomycete fungi which have white spores. They mostly have a tough stem and the capability of shrivelling up during a dry period and later recovering. The widely consumed edible fungus Lentinula edodes, the Shiitake mushroom, is a member of this family...
family. The genus is monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
, containing the single species Pleurocybella porrigens, widespread in temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
forests of the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
. P. porrigens, known as the angel wing, is a white-rot wood-decay fungus
Wood-decay fungus
A wood-decay fungus is a variety of fungus that digests moist wood, causing it to rot. Some wood-decay fungi attack dead wood, such as brown rot, and some, such as Armillaria , are parasitic and colonize living trees. Fungi that not only grow on wood but actually cause it to decay, are called...
on conifer wood, particularly hemlock (genus Tsuga
Tsuga
Tsuga is a genus of conifers in the family Pinaceae. The common name hemlock is derived from a perceived similarity in the smell of its crushed foliage to that of the unrelated plant poison hemlock....
). The flesh is thin and fragile compared to the oyster mushrooms (Pleurotus
Pleurotus
Pleurotus is a genus of gilled mushrooms which includes one of the most widely eaten mushrooms, P. ostreatus. Species of Pleurotus may be called oyster, abalone, or tree mushrooms, and are some of the most commonly cultivated edible mushrooms in the world...
ssp.).
Pleurocybella porrigens has historically been generally regarded as edible
Edible mushroom
Edible mushrooms are the fleshy and edible fruiting bodies of several species of fungi. Mushrooms belong to the macrofungi, because their fruiting structures are large enough to be seen with the naked eye. They can appear either below ground or above ground where they may be picked by hand...
but this has been brought in to question by recent deaths apparently associated with P. porrigens consumption.
Synonyms for Pleurocybella porrigens include Pleurotus
Pleurotus
Pleurotus is a genus of gilled mushrooms which includes one of the most widely eaten mushrooms, P. ostreatus. Species of Pleurotus may be called oyster, abalone, or tree mushrooms, and are some of the most commonly cultivated edible mushrooms in the world...
porrigens, Phyllotus porrigens, Dendrosarcus porrigens, Pleurotellus porrigens, and Nothopanus
Nothopanus
Nothopanus is a genus of fungus in the Marasmiaceae family. The genus was circumscribed by American mycologist Rolf Singer in 1944....
porrigens.
Toxicity
Although P. porrigens is generally regarded as edible, as of 2011, it has been implicated in two documented outbreaks involving fatal encephalopathy. Both incidents were in Japan, and most victims had pre-existing kidneyKidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
disorders.
The first incident occurred in September and October 2004 across nine prefectures in Japan, and involved the sickening of 59 people and the eventual death of 17. Most of those who died had pre-existing liver problems, and the average age of those effected was 70. Death occurred between 13 and 29 days after the onset of symptoms, and the onset of symptoms occurred at most three weeks after consumption of P. porrigens.
The second incident occurred in 2009, when a 65 year old man who had been on hemodialysis died from acute encephalopathy after eating P. porrigens.
The mechanism of action for the toxicity of P. porrigens has not been definitively established, but several possibilities have been suggested. It has been demonstrated that P. porrigens contains an unusual unstable amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
which is toxic to the brain cells of rats in cell culture studies, but it has not yet been possible to definitively determine that this was the cause of the fatal encephalopathies. Other mechanisms have been suggested for P. porrigens apparent toxicity, including the possibility that cyanide levels in P. porrigens may be high enough to be toxic.