Paxillus involutus
Encyclopedia
Paxillus involutus, commonly known as the brown roll-rim, common roll-rim, or poison pax, is a basidiomycete fungus
widely distributed across the Northern Hemisphere
. It has been unintentionally introduced
to Australia
, New Zealand
, and South America
, where it has likely been transported in soil with European trees. Various shades of brown in colour, the fruit body
grows up to 6 cm (2.4 in) high and has a funnel-shaped cap
up to 12 cm (5 in) wide with a distinctive inrolled rim and decurrent
gills that may be pore-like close to the stipe
. Although it has gills, it is more closely related to the pored bolete
s than to typical gilled mushrooms. It was first described by Pierre Bulliard
in 1785, and was given its current binomial name
by Elias Magnus Fries
in 1838. Genetic testing suggests that Paxillus involutus may be a species complex
rather than a single species.
A common mushroom of deciduous
and coniferous woods and grassy areas in late summer and autumn, Paxillus involutus forms ectomycorrhizal relationships with a broad range of tree species. These benefit from the symbiosis
as the fungus reduces their intake of heavy metals and increases resistance to pathogens such as Fusarium oxysporum
. Previously considered edible
and eaten widely in Eastern
and Central Europe
, it has since been found to be dangerously poisonous, responsible for the death of German mycologist Julius Schäffer
in 1944. It had been recognised as causing gastric upsets when eaten raw, but was more recently found to cause potentially fatal autoimmune hemolysis
, even in those who had consumed the mushroom for years without any other ill effects. An antigen
in the mushroom triggers the immune system
to attack red blood cells. Serious and potentially fatal complications include acute renal failure, shock, acute respiratory failure
, and disseminated intravascular coagulation
.
in 1785 as Agaricus contiguus, although the 1786 combination Agaricus involutus of August Batsch
is taken as the first valid description. James Bolton
published a description of what he called Agaricus adscendibus in 1788; the taxonomical
authority Index Fungorum
considers this to be synonymous with P. involutus. Additional synonyms include Omphalia involuta described by Samuel Frederick Gray
in 1821, and Rhymovis involuta, published by Gottlob Ludwig Rabenhorst
in 1844. The species gained its current binomial name
in 1838 when the 'father of mycology', Swedish naturalist Elias Magnus Fries
erected the genus Paxillus
, and set it as the type species
. The starting date of fungal taxonomy
had been set as January 1, 1821, to coincide with the date of Fries' works, which meant that names coined earlier than this date required sanction
by Fries (indicated in the name by a colon) to be considered valid
. It was thus written Paxillus involutus (Batsch:Fr.) Fr. However, a 1987 revision of the International Code of Botanical Nomenclature set the starting date at May 1, 1753, the date of publication of Linnaeus' seminal work, the Species Plantarum
. Hence the name no longer requires the ratification of Fries' authority.
The genus was later placed in a new family, Paxillaceae
, by French mycologist René Maire
who held it to be related to both agaric
s and boletes. Although it has gills rather than pores, it has long been recognised as belonging to the pored mushrooms of the order Boletales
rather than the traditional agarics. The generic name is derived from the Latin
for 'peg' or 'plug', and the specific epithet involutus, 'inrolled', refers to the cap margin. Common name
s include the naked brimcap, poison paxillus, inrolled pax, poison pax, common roll-rim, brown roll-rim, and brown chanterelle. Gray called it the "involved navel-stool" in his 1821 compendium of British flora.
Studies of the ecology and genetics of Paxillus involutus indicate that it may form a complex
of multiple similar-looking species. In a field study near Uppsala
, Sweden, conducted from 1981 to 1983, mycologist Nils Fries found that there were three populations of P. involutus unable to breed with each other. One was found under conifers and mixed woodlands, while the other two were found in parklands, associated with nearby birch trees. He found that the first group tended to produce single isolated fruit bodies which had a thinner stipe and cap which was less inrolled at the margins, while the fruit bodies of the other two populations tended to appear in groups, and have thicker stipes, and caps with more inrolled and sometimes undulating margins. However, there were only general tendencies and he was unable to detect any consistent macroscopic or microscopic features that firmly differentiate them. A molecular study comparing the DNA sequence
s of specimens of Paxillus involutus collected from various habitats in Bavaria
found that those collected from parks and gardens showed a close relationship with the North American species P. vernalis
, while those from forests were allied with P. filamentosus
. The authors suggested the park populations may have been introduced from North America. A multi-gene analysis of European isolates showed that P. involutus sensu lato (in the loose sense) could be separated into four distinct, genetically isolated lineages corresponding to P. obscurosporus, P. involutus sensu stricto (in the strict sense), P. validus, and a fourth species that has not yet been identified. Changes in host range have occurred frequently and independently among strains within this species complex.
, the epigeous (aboveground) fruit body
may be up to 6 cm (2.4 in) high. The cap
, initially convex then more funnel-shaped (infundibuliform) with a depressed centre and rolled rim (hence the common name), may be reddish-, yellowish- or olive-brown in colour and typically 4–12 cm (1.6–5 in) wide; the cap diameter does not get larger than 15 cm (5.9 in). The cap surface is initially downy and later smooth, becoming sticky when wet. The cap and cap margin initially serve to protect the gills of young fruit bodies: this is termed pilangiocarpic development. The narrow brownish yellow gills are decurrent and forked, and can be peeled easily from the flesh (as is the case with the pores of boletes). Gills further down toward the stipe become more irregular and anastomose
, and can even resemble the pores of bolete-type fungi. The fungus darkens when bruised and older specimens may have darkish patches. The juicy yellowish flesh
has a mild to faintly sour or sharp odor and taste, and has been described as well-flavored upon cooking. Of similar colour to the cap, the short stipe
can be crooked and tapers toward the base.
The spore print
is brown, and the dimensions of the ellipsoid (oval-shaped) spores are 7.5–9 by 5–6 μm
.
The hymenium
has cystidia both on the gill edge and face (cheilo- and pleurocystidia respectively), which are slender and filament-like, typically measuring 40–65 by 8–10.5 μm.
, many of which have some degree of toxicity themselves. However, the lack of a milky exudate distinguishes it from any milk cap. One of the more similar is L. turpis
, which presents a darker olive colouration. The related North American Paxillus vernalis has a darker spore print, thicker stipe and is found under aspen, whereas the closer relative P. filamentosus is more similar in appearance to P. involutus. A rare species that grows only in association with alder
, P. filamentosus can be distinguished from it by the pressed-down scales on the cap surface that point towards the cap margin, a light yellow flesh that bruises only slightly brown, and deep yellow-ochre gills that do not change colour upon injury
The most similar species are two once thought to be part of P. involutus in Europe. Paxillus obscurosporus has larger fruit bodies than P. involutus, with caps up to 40 cm (15.7 in) wide whose margins tend to unroll and flatten with age, and a layer of cream-coloured mycelia covering the base of its tapered stipe. P. validus, also known only from Europe, has caps up to 20 cm (7.9 in) wide with a stipe that is more or less equal in width throughout its length. Found under broadleaved trees in parks, it can be reliably distinguished from P. involutus (and other Paxillus species) by the presence of crystals up to 2.5 μm long in the rhizomorphs
, as the crystals found in rhizomorphs of other Paxillus species do not exceed 0.5 μm long.
and deciduous
tree species. Because the fungus has somewhat unspecialised nutrient requirements and a relatively broad host
specificity, it has been frequently used in research and seedling inoculation programs. There is evidence of the benefit to trees of this arrangement: in one experiment where P. involutus was cultivated on the root exudate of red pine (Pinus resinosa), the root showed markedly increased resistance to pathogenic strains of the ubiquitous soil fungus Fusarium oxysporum
. Seedlings inoculated with P. involutus also showed increased resistance to Fusarium. Thus P. involutus may be producing antifungal compounds which protect the host plants from root rot. Paxillus involutus also decreases the uptake of certain toxic elements, acting as a buffer against heavy metal toxicity in the host plant. For example, the fungus decreased the toxicity of cadmium
and zinc
to Scots pine (Pinus sylvestris) seedlings: even though cadmium itself inhibits ectomycorrhiza formation in seedlings, colonization with P. involutus decreases cadmium and zinc transport to the plant shoots and alters the ratio of zinc transported to the roots and shoots, causing more cadmium to be retained in the roots of the seedlings rather than distributed through its entire metabolism. Evidence suggests that the mechanism for this detoxification involves the cadmium binding to the fungal cell wall
s, as well as accumulating in the vacuolar compartments
. Further, ectomycorrhizal hyphae exposed to copper
or cadmium drastically increase production of a metallothionein
—a low molecular weight protein that binds metals.
The presence of Paxillus involutus is related to much reduced numbers of bacteria associated with the roots of Pinus sylvestris. Instead bacteria are found on the external mycelium. The types of bacteria change as well; a Finnish study published in 1997 found that bacterial communities under P. sylvestris without mycorrhizae metabolised organic
and amino acid
s, while communities among P. involutus metabolised the sugar fructose
. Paxillus involutus benefits from the presence of some species of bacteria in the soil it grows in. As the fungus grows it excretes polyphenol
s, waste products that are toxic to itself and impede its growth, but these compounds are metabolised by some bacteria, resulting in increased fungal growth. Bacteria also produce certain compounds such as citric
and malic acid
, which stimulate P. involutus.
Highly abundant, the brown roll-rim is found across the Northern Hemisphere, Europe and Asia, with records from India, China, Japan, Iran, and Turkey's eastern Anatolia
. It is equally widely distributed across northern North America, extending north to Alaska
, where it has been collected from tundra
near Coldfoot
in the interior of the state. In southwestern Greenland, P. involutus has been recorded under the birch species Betula nana, B. pubescens and B. glandulosa. The mushroom is more common in coniferous woods in Europe, but is also closely associated with birch (Betula pendula). Within woodland, it prefers wet places or boggy ground, and avoids calcareous
(chalky) soils. It has been noted to grow alongside Boletus badius
in Europe, and Leccinum scabrum and Lactarius plumbeus in the Pacific Northwest
region of North America. There it is found in both deciduous and coniferous woodland, commonly under plantings of white birch (Betula papyrifera) in urban areas. It is one of a small number of fungal species which thrive in Pinus radiata plantations planted outside their natural range. A study of polluted Scots pine forest around Oulu
in northern Finland found that P. involutus became more abundant in more polluted areas while other species declined. Emissions from pulp mills, fertiliser, heating and traffic were responsible for the pollution, which was measured by sulfur levels in the pine needles.
Paxillus involutus can be found growing on lawn
s and old meadow
s throughout its distribution. Fruit bodies are generally terrestrial, though they may be found on woody material around tree stumps. They generally appear in autumn and late summer. In California, David Arora
discerned a larger form associated with oak and pine which appears in late autumn and winter, as well as the typical form that is associated with birch plantings and appears in autumn. Several species of flies and beetles have been recorded using the fruit bodies to rear their young. The mushroom can be infected by Hypomyces chrysospermus
, or bolete eater, a mould species that parasitises Boletales
members. Infection results in the appearance of a whitish powder that first manifests on the pores, then spreads over the surface of the mushroom, becoming golden yellow to reddish-brown in maturity.
Australian mycologist John Burton Cleland
noted it occurring under larch
(Larix), oak, pine, birch and other introduced
trees in South Australia
in 1934, and it has subsequently been recorded in New South Wales
, Victoria
(where it was found near Betula and Populus) and Western Australia
. It has been recorded under introduced birch
(Betula) and hazel
(Corylus) in New Zealand. Mycologist Rolf Singer
reported a similar situation in South America, with the species recorded under introduced trees in Chile
. It is likely to have been transported to those countries in the soil of imported European trees.
and Eastern Europe
until World War II, although English guidebooks did not recommend it. In Poland, the mushroom was often eaten after pickling or salting. It was known to be a gastrointestinal irritant when ingested raw but had been presumed edible after cooking. Questions were first raised about its toxicity after German mycologist Julius Schäffer
died after eating it in October 1944. About an hour after he and his wife ate a meal prepared with the mushrooms, Schäffer developed vomiting, diarrhea, and fever. His condition worsened to the point where he was admitted to hospital the following day and developed renal failure
, perishing after 17 days.
In the mid-1980s, Swiss physician René Flammer discovered an antigen
within the mushroom that stimulates an autoimmune reaction causing the body's immune cells to consider its own red blood cells as foreign and attack them. Despite this, it was not until 1990 that guidebooks firmly warned against eating P. involutus, and one Italian guidebook recommended it as edible in 1998. The relatively rare immunohemolytic syndrome occurs following the repeated ingestion of Paxillus mushrooms. Most commonly it arises when the person has ingested the mushroom for a long period of time, sometimes for many years, and has shown mild gastrointestinal symptoms on previous occasions. The Paxillus syndrome is better classed as an allergic reaction than a toxicological reaction as it is not caused by a genuinely poisonous substance but by the antigen in the mushroom. The antigen is still of unknown structure but it stimulates the formation of IgG antibodies in the blood serum
. In the course of subsequent meals, antigen-antibody complexes
are formed; these complexes attach to the surface of blood cells and eventually lead to their breakdown
.
Poisoning symptoms are rapid in onset, consisting initially of vomiting, diarrhea, abdominal pain, and associated decreased blood volume
. Shortly after these initial symptoms appear, hemolysis
develops, resulting in reduced urine output
, hemoglobin in the urine
or outright absence of urine formation
, and anemia
. Medical laboratory tests consist of testing for the presence of increasing bilirubin
and free hemoglobin, and falling haptoglobin
s. Hemolysis may lead to numerous complications including acute renal failure, shock, acute respiratory failure
, and disseminated intravascular coagulation
. These complications can cause significant morbidity with fatalities having been reported.
There is no antidote for poisoning, only supportive treatment consisting of monitoring complete blood count
, renal function, blood pressure, and fluid and electrolyte balance and correcting abnormalities. The use of corticosteroid
s may be a useful adjunct in treatment, as they protect blood cells against hemolysis, thereby reducing complications. Plasmapheresis
reduces the circulating immune complexes in the blood which cause the hemolysis, and may be beneficial in improving the outcome. Additionally, hemodialysis
can be used for patients with compromised renal function or renal failure.
Paxillus involutus also contains agents which appear to damage chromosome
s; it is unclear whether these have carcinogen
ic or mutagen
ic potential. Two compounds that have been identified are the phenols
involutone and involutin; the latter is responsible for the brownish discolouration upon bruising.
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...
widely distributed across 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...
. It has been unintentionally introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
to Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, where it has likely been transported in soil with European trees. Various shades of brown in colour, the fruit body
Basidiocarp
In fungi, a basidiocarp, basidiome or basidioma , is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do not produce such structures...
grows up to 6 cm (2.4 in) high and has a funnel-shaped cap
Pileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...
up to 12 cm (5 in) wide with a distinctive inrolled rim and decurrent
Decurrent
Decurrent is a term used in botany and mycology to describe plant or fungal parts that extend downward.In botany, the term is most often applied to leaf blades that partly wrap or have wings around the stem or petiole and extend down along the stem...
gills that may be pore-like close to the stipe
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...
. Although it has gills, it is more closely related to the pored bolete
Bolete
A bolete is a type of fungal fruiting body characterized by the presence of a pileus that is clearly differentiated from the stipe, with a spongy surface of pores on the underside of the pileus...
s than to typical gilled mushrooms. It was first described by Pierre Bulliard
Jean Baptiste François Pierre Bulliard
Jean Baptiste François Pierre Bulliard was a French physician and botanist....
in 1785, and was given its current binomial name
Binomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...
by Elias Magnus Fries
Elias Magnus Fries
-External links:*, Authors of fungal names, Mushroom, the Journal of Wild Mushrooming.*...
in 1838. Genetic testing suggests that Paxillus involutus may be a species complex
Species complex
A species complex is a group of closely related species, where the exact demarcation between species is often unclear or cryptic owing to their recent and usually still incomplete reproductive isolation. Ring species, superspecies and cryptic species complex are example of species complex...
rather than a single species.
A common mushroom of deciduous
Temperate deciduous forest
A temperate deciduous forest, more precisely termed temperate broadleaf forest or temperate broadleaved forest, is a biome found in North America, southern South America, Europe, and Asia. A temperate deciduous forest consists of trees that lose their leaves every year...
and coniferous woods and grassy areas in late summer and autumn, Paxillus involutus forms ectomycorrhizal relationships with a broad range of tree species. These benefit from the symbiosis
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
as the fungus reduces their intake of heavy metals and increases resistance to pathogens such as Fusarium oxysporum
Fusarium oxysporum
Fusarium oxysporum Schlecht. as emended by Snyder and Hansen comprises all the species, varieties and forms recognized by Wollenweber and Reinking within an infrageneric grouping called section Elegans...
. Previously considered 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...
and eaten widely in Eastern
Eastern Europe
Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region"...
and Central Europe
Central Europe
Central Europe or alternatively Middle Europe is a region of the European continent lying between the variously defined areas of Eastern and Western Europe...
, it has since been found to be dangerously poisonous, responsible for the death of German mycologist Julius Schäffer
Julius Schäffer
Julius Schäffer was a German mycologist. His contributions include studies on the Agaricales , especially the genus Russula, about which he wrote a monograph in 1933. Later, he revised the genus in the series Die Pilze Mitteleuropas ; his notes were published posthumously by his wife Liesel in...
in 1944. It had been recognised as causing gastric upsets when eaten raw, but was more recently found to cause potentially fatal autoimmune hemolysis
Hemolysis
Hemolysis —from the Greek meaning "blood" and meaning a "loosing", "setting free" or "releasing"—is the rupturing of erythrocytes and the release of their contents into surrounding fluid...
, even in those who had consumed the mushroom for years without any other ill effects. An antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
in the mushroom triggers the immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
to attack red blood cells. Serious and potentially fatal complications include acute renal failure, shock, acute respiratory failure
Respiratory failure
The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...
, and disseminated intravascular coagulation
Disseminated intravascular coagulation
Disseminated intravascular coagulation , also known as disseminated intravascular coagulopathy or consumptive coagulopathy, is a pathological activation of coagulation mechanisms that happens in response to a variety of diseases. DIC leads to the formation of small blood clots inside the blood...
.
Taxonomy and naming
The brown roll-rim was described by French mycologist Pierre BulliardJean Baptiste François Pierre Bulliard
Jean Baptiste François Pierre Bulliard was a French physician and botanist....
in 1785 as Agaricus contiguus, although the 1786 combination Agaricus involutus of August Batsch
August Batsch
Dr August Johann Georg Karl Batsch was a German naturalist. He was a recognised authority on mushrooms, and also described new species of ferns, bryophytes, and seed plants.- Life and career :...
is taken as the first valid description. James Bolton
James Bolton
James Bolton was an English naturalist, botanist, mycologist, and illustrator.-Background:James Bolton was born near Warley in the West Riding of Yorkshire in 1735, the son of William Bolton, a weaver. James initially followed in his father's trade, but later became a self-taught art teacher and...
published a description of what he called Agaricus adscendibus in 1788; the taxonomical
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
authority Index Fungorum
Index Fungorum
Index Fungorum, an international project to index all formal names in the Fungi Kingdom. Somewhat comparable to the IPNI, but with more contributing institutions....
considers this to be synonymous with P. involutus. Additional synonyms include Omphalia involuta described by Samuel Frederick Gray
Samuel Frederick Gray
Samuel Frederick Gray was a British botanist, mycologist, and pharmacologist. He was the father of the zoologists John Edward Gray and George Robert Gray.-Background:...
in 1821, and Rhymovis involuta, published by Gottlob Ludwig Rabenhorst
Gottlob Ludwig Rabenhorst
Gottlob Ludwig Rabenhorst was a German botanist. He was a student in Berlin and Belzig from 1822 to 1830, a pharmacist in Luckau until 1840, and received his doctorate in Jena in 1841. Rabenhorst edited the scientific journal Hedwigia from 1852 to 1878....
in 1844. The species gained its current binomial name
Binomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...
in 1838 when the 'father of mycology', Swedish naturalist Elias Magnus Fries
Elias Magnus Fries
-External links:*, Authors of fungal names, Mushroom, the Journal of Wild Mushrooming.*...
erected the genus Paxillus
Paxillus
Paxillus is a genus of mushrooms of which most are known to be poisonous or inedible. The widespread genus contains 15 species. Species include Paxillus involutus and Paxillus vernalis...
, and set it as the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
. The starting date of fungal taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
had been set as January 1, 1821, to coincide with the date of Fries' works, which meant that names coined earlier than this date required sanction
Sanctioned name
In mycology, a sanctioned name is a name that was adopted in certain works of Christiaan Hendrik Persoon or Elias Magnus Fries, which are considered major points in fungal taxonomy.-Definition and effects:...
by Fries (indicated in the name by a colon) to be considered valid
Correct name (botany)
In botany, the correct name according to the International Code of Botanical Nomenclature is the one and only botanical name that is to be used for a particular taxon, when that taxon has a particular circumscription, position and rank. Determining whether a name is correct is a complex procedure...
. It was thus written Paxillus involutus (Batsch:Fr.) Fr. However, a 1987 revision of the International Code of Botanical Nomenclature set the starting date at May 1, 1753, the date of publication of Linnaeus' seminal work, the Species Plantarum
Species Plantarum
Species Plantarum was first published in 1753, as a two-volume work by Carl Linnaeus. Its prime importance is perhaps that it is the primary starting point of plant nomenclature as it exists today. This means that the first names to be considered validly published in botany are those that appear...
. Hence the name no longer requires the ratification of Fries' authority.
The genus was later placed in a new family, Paxillaceae
Paxillaceae
The Paxillaceae are a family of mushrooms bearing close affinity to the Boletes. Collectively, the family contains nine genera and 78 species. The type genus is Paxillus, containing fungi with decurrent gills, and Gyrodon, which has members with decurrent pores, among others...
, by French mycologist René Maire
René Maire
René Charles Joseph Ernest Maire was a French botanist and mycologist. His major work was the Flore de l'Afrique du Nord in 16 volumes published posthumously in 1953. He collected plants from Algeria, Morocco, France, and Mali for the herbarium of the National Botanic Garden of Belgium.- Biography...
who held it to be related to both agaric
Agaric
An agaric is a type of fungal fruiting body characterized by the presence of a pileus that is clearly differentiated from the stipe , with lamellae on the underside of the pileus. "Agaric" can also refer to a basidiomycete species characterized by an agaric-type fruiting body...
s and boletes. Although it has gills rather than pores, it has long been recognised as belonging to the pored mushrooms of the order Boletales
Boletales
The Boletales are an order of Agaricomycetes, containing over 1300 species with a diverse array of fruiting body types. The boletes are the best known members of this group, and until recently, the Boletales were thought to only contain boletes...
rather than the traditional agarics. The generic name is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for 'peg' or 'plug', and the specific epithet involutus, 'inrolled', refers to the cap margin. Common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
s include the naked brimcap, poison paxillus, inrolled pax, poison pax, common roll-rim, brown roll-rim, and brown chanterelle. Gray called it the "involved navel-stool" in his 1821 compendium of British flora.
Studies of the ecology and genetics of Paxillus involutus indicate that it may form a complex
Species complex
A species complex is a group of closely related species, where the exact demarcation between species is often unclear or cryptic owing to their recent and usually still incomplete reproductive isolation. Ring species, superspecies and cryptic species complex are example of species complex...
of multiple similar-looking species. In a field study near Uppsala
Uppsala
- Economy :Today Uppsala is well established in medical research and recognized for its leading position in biotechnology.*Abbott Medical Optics *GE Healthcare*Pfizer *Phadia, an offshoot of Pharmacia*Fresenius*Q-Med...
, Sweden, conducted from 1981 to 1983, mycologist Nils Fries found that there were three populations of P. involutus unable to breed with each other. One was found under conifers and mixed woodlands, while the other two were found in parklands, associated with nearby birch trees. He found that the first group tended to produce single isolated fruit bodies which had a thinner stipe and cap which was less inrolled at the margins, while the fruit bodies of the other two populations tended to appear in groups, and have thicker stipes, and caps with more inrolled and sometimes undulating margins. However, there were only general tendencies and he was unable to detect any consistent macroscopic or microscopic features that firmly differentiate them. A molecular study comparing the DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
s of specimens of Paxillus involutus collected from various habitats in Bavaria
Bavaria
Bavaria, formally the Free State of Bavaria is a state of Germany, located in the southeast of Germany. With an area of , it is the largest state by area, forming almost 20% of the total land area of Germany...
found that those collected from parks and gardens showed a close relationship with the North American species P. vernalis
Paxillus vernalis
Paxillus vernalis is a basidiomycete fungus found in montane forests in northern North America. It closely resembles Paxillus involutus. It was first described by Roy Watling in 1969.- External links :*...
, while those from forests were allied with P. filamentosus
Paxillus filamentosus
Paxillus filamentosus, commonly known as the alder roll-rim, is a basidiomycete fungus which is associated with alder in northern Europe and southwestern Greenland, and North America. It closely resembles Paxillus involutus, but its fruit bodies are generally smaller....
. The authors suggested the park populations may have been introduced from North America. A multi-gene analysis of European isolates showed that P. involutus sensu lato (in the loose sense) could be separated into four distinct, genetically isolated lineages corresponding to P. obscurosporus, P. involutus sensu stricto (in the strict sense), P. validus, and a fourth species that has not yet been identified. Changes in host range have occurred frequently and independently among strains within this species complex.
Description
Resembling a brown wooden topTop
A top is a toy that can be spun on an axis, balancing on a point. This motion is produced in the most simple forms of top by twirling the stem using the fingers. More sophisticated tops are spun by by holding the axis firmly while pulling a string or twisting a stick or pushing an auger as shown...
, the epigeous (aboveground) fruit body
Basidiocarp
In fungi, a basidiocarp, basidiome or basidioma , is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do not produce such structures...
may be up to 6 cm (2.4 in) high. The cap
Pileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...
, initially convex then more funnel-shaped (infundibuliform) with a depressed centre and rolled rim (hence the common name), may be reddish-, yellowish- or olive-brown in colour and typically 4–12 cm (1.6–5 in) wide; the cap diameter does not get larger than 15 cm (5.9 in). The cap surface is initially downy and later smooth, becoming sticky when wet. The cap and cap margin initially serve to protect the gills of young fruit bodies: this is termed pilangiocarpic development. The narrow brownish yellow gills are decurrent and forked, and can be peeled easily from the flesh (as is the case with the pores of boletes). Gills further down toward the stipe become more irregular and anastomose
Anastomosis
An anastomosis is the reconnection of two streams that previously branched out, such as blood vessels or leaf veins. The term is used in medicine, biology, mycology and geology....
, and can even resemble the pores of bolete-type fungi. The fungus darkens when bruised and older specimens may have darkish patches. The juicy yellowish flesh
Trama (mycology)
In mycology trama is a term for the inner, fleshy portion of a mushroom's basidiocarp, or fruit body. It is distinct from the outer layer of tissue, known as the pileipellis or cuticle, and from the spore-bearing tissue layer known as the hymenium....
has a mild to faintly sour or sharp odor and taste, and has been described as well-flavored upon cooking. Of similar colour to the cap, the short stipe
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...
can be crooked and tapers toward the base.
The spore print
Spore print
thumb|300px|right|Making a spore print of the mushroom Volvariella volvacea shown in composite: mushroom cap laid on white and dark paper; cap removed after 24 hours showing pinkish-tan spore print...
is brown, and the dimensions of the ellipsoid (oval-shaped) spores are 7.5–9 by 5–6 μm
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
.
The hymenium
Hymenium
The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some cells develop into sterile cells called cystidia or...
has cystidia both on the gill edge and face (cheilo- and pleurocystidia respectively), which are slender and filament-like, typically measuring 40–65 by 8–10.5 μm.
Similar species
The brownish colour and funnel-like shape of P. involutus can lead to its confusion with several species of LactariusLactarius
Lactarius is a genus of mushroom-producing fungi. The genus, collectively known commonly as milk-caps, are characterized by the fact that they exude a milky fluid if cut or damaged...
, many of which have some degree of toxicity themselves. However, the lack of a milky exudate distinguishes it from any milk cap. One of the more similar is L. turpis
Lactarius turpis
Lactarius turpis is commonly known as the Ugly Milk-cap in English. It is found naturally in Europe and Siberia, and has been introduced to Australia and New Zealand...
, which presents a darker olive colouration. The related North American Paxillus vernalis has a darker spore print, thicker stipe and is found under aspen, whereas the closer relative P. filamentosus is more similar in appearance to P. involutus. A rare species that grows only in association with alder
Alder
Alder is the common name of a genus of flowering plants belonging to the birch family . The genus comprises about 30 species of monoecious trees and shrubs, few reaching large size, distributed throughout the North Temperate Zone and in the Americas along the Andes southwards to...
, P. filamentosus can be distinguished from it by the pressed-down scales on the cap surface that point towards the cap margin, a light yellow flesh that bruises only slightly brown, and deep yellow-ochre gills that do not change colour upon injury
The most similar species are two once thought to be part of P. involutus in Europe. Paxillus obscurosporus has larger fruit bodies than P. involutus, with caps up to 40 cm (15.7 in) wide whose margins tend to unroll and flatten with age, and a layer of cream-coloured mycelia covering the base of its tapered stipe. P. validus, also known only from Europe, has caps up to 20 cm (7.9 in) wide with a stipe that is more or less equal in width throughout its length. Found under broadleaved trees in parks, it can be reliably distinguished from P. involutus (and other Paxillus species) by the presence of crystals up to 2.5 μm long in the rhizomorphs
Mycelial cord
Mycelial cords are linear aggregations of parallel-oriented hyphae. The mature cords are composed of wide, empty vessel hyphae surrounded by narrower sheathing hyphae...
, as the crystals found in rhizomorphs of other Paxillus species do not exceed 0.5 μm long.
Ecology, distribution and habitat
Paxillus involutus forms ectomycorrhizal relationships with a number of coniferousPinophyta
The conifers, division Pinophyta, also known as division Coniferophyta or Coniferae, are one of 13 or 14 division level taxa within the Kingdom Plantae. Pinophytes are gymnosperms. They are cone-bearing seed plants with vascular tissue; all extant conifers are woody plants, the great majority being...
and deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
tree species. Because the fungus has somewhat unspecialised nutrient requirements and a relatively broad host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
specificity, it has been frequently used in research and seedling inoculation programs. There is evidence of the benefit to trees of this arrangement: in one experiment where P. involutus was cultivated on the root exudate of red pine (Pinus resinosa), the root showed markedly increased resistance to pathogenic strains of the ubiquitous soil fungus Fusarium oxysporum
Fusarium oxysporum
Fusarium oxysporum Schlecht. as emended by Snyder and Hansen comprises all the species, varieties and forms recognized by Wollenweber and Reinking within an infrageneric grouping called section Elegans...
. Seedlings inoculated with P. involutus also showed increased resistance to Fusarium. Thus P. involutus may be producing antifungal compounds which protect the host plants from root rot. Paxillus involutus also decreases the uptake of certain toxic elements, acting as a buffer against heavy metal toxicity in the host plant. For example, the fungus decreased the toxicity of cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
and zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
to Scots pine (Pinus sylvestris) seedlings: even though cadmium itself inhibits ectomycorrhiza formation in seedlings, colonization with P. involutus decreases cadmium and zinc transport to the plant shoots and alters the ratio of zinc transported to the roots and shoots, causing more cadmium to be retained in the roots of the seedlings rather than distributed through its entire metabolism. Evidence suggests that the mechanism for this detoxification involves the cadmium binding to the fungal cell wall
Cell wall
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...
s, as well as accumulating in the vacuolar compartments
Vacuole
A vacuole is a membrane-bound organelle which is present in all plant and fungal cells and some protist, animal and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution, though in certain...
. Further, ectomycorrhizal hyphae exposed to copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
or cadmium drastically increase production of a metallothionein
Metallothionein
Metallothionein is a family of cysteine-rich, low molecular weight proteins. They are localized to the membrane of the Golgi apparatus...
—a low molecular weight protein that binds metals.
The presence of Paxillus involutus is related to much reduced numbers of bacteria associated with the roots of Pinus sylvestris. Instead bacteria are found on the external mycelium. The types of bacteria change as well; a Finnish study published in 1997 found that bacterial communities under P. sylvestris without mycorrhizae metabolised organic
Organic acid
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are relatively stronger acids. The relative stability of the conjugate...
and 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...
s, while communities among P. involutus metabolised the sugar fructose
Fructose
Fructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...
. Paxillus involutus benefits from the presence of some species of bacteria in the soil it grows in. As the fungus grows it excretes polyphenol
Polyphenol
Polyphenols are a structural class of natural, synthetic, and semisynthetic organic chemicals characterized by the presence of large multiples of phenol structural units...
s, waste products that are toxic to itself and impede its growth, but these compounds are metabolised by some bacteria, resulting in increased fungal growth. Bacteria also produce certain compounds such as citric
Citric acid
Citric acid is a weak organic acid. It is a natural preservative/conservative and is also used to add an acidic, or sour, taste to foods and soft drinks...
and malic acid
Malic acid
Malic acid is an organic compound with the formula HO2CCH2CHOHCO2H. It is a dicarboxylic acid which is made by all living organisms, contributes to the pleasantly sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms , though only the L-isomer exists...
, which stimulate P. involutus.
Anatolia
Anatolia is a geographic and historical term denoting the westernmost protrusion of Asia, comprising the majority of the Republic of Turkey...
. It is equally widely distributed across northern North America, extending north to Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, where it has been collected from tundra
Tundra
In physical geography, tundra is a biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sami word tūndâr "uplands," "treeless mountain tract." There are three types of tundra: Arctic tundra, alpine...
near Coldfoot
Coldfoot, Alaska
Coldfoot is a census-designated place in Yukon-Koyukuk Census Area in the U.S. state of Alaska. The population was 13 at the 2000 census....
in the interior of the state. In southwestern Greenland, P. involutus has been recorded under the birch species Betula nana, B. pubescens and B. glandulosa. The mushroom is more common in coniferous woods in Europe, but is also closely associated with birch (Betula pendula). Within woodland, it prefers wet places or boggy ground, and avoids calcareous
Calcareous
Calcareous is an adjective meaning mostly or partly composed of calcium carbonate, in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.-In zoology:...
(chalky) soils. It has been noted to grow alongside Boletus badius
Boletus badius
Boletus badius , and commonly known as the Bay Bolete is an edible, pored mushroom from Europe and North America...
in Europe, and Leccinum scabrum and Lactarius plumbeus in the Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
region of North America. There it is found in both deciduous and coniferous woodland, commonly under plantings of white birch (Betula papyrifera) in urban areas. It is one of a small number of fungal species which thrive in Pinus radiata plantations planted outside their natural range. A study of polluted Scots pine forest around Oulu
Oulu
Oulu is a city and municipality of inhabitants in the region of Northern Ostrobothnia, in Finland. It is the most populous city in Northern Finland and the sixth most populous city in the country. It is one of the northernmost larger cities in the world....
in northern Finland found that P. involutus became more abundant in more polluted areas while other species declined. Emissions from pulp mills, fertiliser, heating and traffic were responsible for the pollution, which was measured by sulfur levels in the pine needles.
Paxillus involutus can be found growing on lawn
Lawn
A lawn is an area of aesthetic and recreational land planted with grasses or other durable plants, which usually are maintained at a low and consistent height. Low ornamental meadows in natural landscaping styles are a contemporary option of a lawn...
s and old meadow
Meadow
A meadow is a field vegetated primarily by grass and other non-woody plants . The term is from Old English mædwe. In agriculture a meadow is grassland which is not grazed by domestic livestock but rather allowed to grow unchecked in order to make hay...
s throughout its distribution. Fruit bodies are generally terrestrial, though they may be found on woody material around tree stumps. They generally appear in autumn and late summer. In California, David Arora
David Arora
David Arora is an American mycologist, naturalist, and writer. He is the author of two popular books on mushroom identification, Mushrooms Demystified and All That the Rain Promises and More.......
discerned a larger form associated with oak and pine which appears in late autumn and winter, as well as the typical form that is associated with birch plantings and appears in autumn. Several species of flies and beetles have been recorded using the fruit bodies to rear their young. The mushroom can be infected by Hypomyces chrysospermus
Hypomyces chrysospermus
The bolete eater is a parasitic ascomycete that grows on boletes, turning them a whitish, golden yellow, or tan color. It is found in Europe and North America, as well as southwest Western Australia...
, or bolete eater, a mould species that parasitises Boletales
Boletales
The Boletales are an order of Agaricomycetes, containing over 1300 species with a diverse array of fruiting body types. The boletes are the best known members of this group, and until recently, the Boletales were thought to only contain boletes...
members. Infection results in the appearance of a whitish powder that first manifests on the pores, then spreads over the surface of the mushroom, becoming golden yellow to reddish-brown in maturity.
Australian mycologist John Burton Cleland
John Burton Cleland
Sir John Burton Cleland CBE was a renowned Australian naturalist, microbiologist, mycologist and ornithologist.-Early Life and education:...
noted it occurring under larch
Larch
Larches are conifers in the genus Larix, in the family Pinaceae. Growing from 15 to 50m tall, they are native to much of the cooler temperate northern hemisphere, on lowlands in the north and high on mountains further south...
(Larix), oak, pine, birch and other introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
trees in South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
in 1934, and it has subsequently been recorded in New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
(where it was found near Betula and Populus) and Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
. It has been recorded under introduced birch
Birch
Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...
(Betula) and hazel
Hazel
The hazels are a genus of deciduous trees and large shrubs native to the temperate northern hemisphere. The genus is usually placed in the birch family Betulaceae, though some botanists split the hazels into a separate family Corylaceae.They have simple, rounded leaves with double-serrate margins...
(Corylus) in New Zealand. Mycologist Rolf Singer
Rolf Singer
Rolf Singer was a German-born mycologist and one of the most important taxonomists of gilled mushrooms in the 20th century....
reported a similar situation in South America, with the species recorded under introduced trees in Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
. It is likely to have been transported to those countries in the soil of imported European trees.
Toxicity
Paxillus involutus was widely eaten in CentralCentral Europe
Central Europe or alternatively Middle Europe is a region of the European continent lying between the variously defined areas of Eastern and Western Europe...
and Eastern Europe
Eastern Europe
Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region"...
until World War II, although English guidebooks did not recommend it. In Poland, the mushroom was often eaten after pickling or salting. It was known to be a gastrointestinal irritant when ingested raw but had been presumed edible after cooking. Questions were first raised about its toxicity after German mycologist Julius Schäffer
Julius Schäffer
Julius Schäffer was a German mycologist. His contributions include studies on the Agaricales , especially the genus Russula, about which he wrote a monograph in 1933. Later, he revised the genus in the series Die Pilze Mitteleuropas ; his notes were published posthumously by his wife Liesel in...
died after eating it in October 1944. About an hour after he and his wife ate a meal prepared with the mushrooms, Schäffer developed vomiting, diarrhea, and fever. His condition worsened to the point where he was admitted to hospital the following day and developed renal failure
Renal failure
Renal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...
, perishing after 17 days.
In the mid-1980s, Swiss physician René Flammer discovered an antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
within the mushroom that stimulates an autoimmune reaction causing the body's immune cells to consider its own red blood cells as foreign and attack them. Despite this, it was not until 1990 that guidebooks firmly warned against eating P. involutus, and one Italian guidebook recommended it as edible in 1998. The relatively rare immunohemolytic syndrome occurs following the repeated ingestion of Paxillus mushrooms. Most commonly it arises when the person has ingested the mushroom for a long period of time, sometimes for many years, and has shown mild gastrointestinal symptoms on previous occasions. The Paxillus syndrome is better classed as an allergic reaction than a toxicological reaction as it is not caused by a genuinely poisonous substance but by the antigen in the mushroom. The antigen is still of unknown structure but it stimulates the formation of IgG antibodies in the blood serum
Blood serum
In blood, the serum is the component that is neither a blood cell nor a clotting factor; it is the blood plasma with the fibrinogens removed...
. In the course of subsequent meals, antigen-antibody complexes
Immune complex
An immune complex is formed from the integral binding of an antibody to a soluble antigen. The bound antigen acting as a specific epitope, bound to an antibody is referred to as a singular immune complex....
are formed; these complexes attach to the surface of blood cells and eventually lead to their breakdown
Lysis
Lysis refers to the breaking down of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a "lysate"....
.
Poisoning symptoms are rapid in onset, consisting initially of vomiting, diarrhea, abdominal pain, and associated decreased blood volume
Hypovolemia
In physiology and medicine, hypovolemia is a state of decreased blood volume; more specifically, decrease in volume of blood plasma...
. Shortly after these initial symptoms appear, hemolysis
Hemolysis
Hemolysis —from the Greek meaning "blood" and meaning a "loosing", "setting free" or "releasing"—is the rupturing of erythrocytes and the release of their contents into surrounding fluid...
develops, resulting in reduced urine output
Oliguria
Oliguria is the low output of urine, It is clinically classified as an output below 300-500ml/day. The decreased output of urine may be a sign of dehydration, renal failure, hypovolemic shock, HHNS Hyperosmolar Hyperglycemic Nonketotic Syndrome, multiple organ dysfunction syndrome, urinary...
, hemoglobin in the urine
Hemoglobinuria
In medicine, hemoglobinuria or haemoglobinuria is a condition in which the oxygen transport protein hemoglobin is found in abnormally high concentrations in the urine. The condition is often associated with hemolytic anemia, in which red blood cells are destroyed, thereby increasing levels of free...
or outright absence of urine formation
Anuria
Anuria means nonpassage of urine, in practice is defined as passage of less than 50 milliliters of urine in a day. Anuria is often caused by failure in the function of kidneys. It may also occur because of some severe obstruction like kidney stones or tumours. It may occur with end stage renal...
, and anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
. Medical laboratory tests consist of testing for the presence of increasing bilirubin
Bilirubin
Bilirubin is the yellow breakdown product of normal heme catabolism. Heme is found in hemoglobin, a principal component of red blood cells. Bilirubin is excreted in bile and urine, and elevated levels may indicate certain diseases...
and free hemoglobin, and falling haptoglobin
Haptoglobin
Haptoglobin is a protein that in humans is encoded by the HP gene. In blood plasma, haptoglobin binds free hemoglobin released from erythrocytes with high affinity and thereby inhibits its oxidative activity. The haptoglobin-hemoglobin complex will then be removed by the reticuloendothelial system...
s. Hemolysis may lead to numerous complications including acute renal failure, shock, acute respiratory failure
Respiratory failure
The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...
, and disseminated intravascular coagulation
Disseminated intravascular coagulation
Disseminated intravascular coagulation , also known as disseminated intravascular coagulopathy or consumptive coagulopathy, is a pathological activation of coagulation mechanisms that happens in response to a variety of diseases. DIC leads to the formation of small blood clots inside the blood...
. These complications can cause significant morbidity with fatalities having been reported.
There is no antidote for poisoning, only supportive treatment consisting of monitoring complete blood count
Complete blood count
A complete blood count , also known as full blood count or full blood exam or blood panel, is a test panel requested by a doctor or other medical professional that gives information about the cells in a patient's blood...
, renal function, blood pressure, and fluid and electrolyte balance and correcting abnormalities. The use of corticosteroid
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
s may be a useful adjunct in treatment, as they protect blood cells against hemolysis, thereby reducing complications. Plasmapheresis
Plasmapheresis
Plasmapheresis is the removal, treatment, and return of blood plasma from blood circulation. It is thus an extracorporeal therapy...
reduces the circulating immune complexes in the blood which cause the hemolysis, and may be beneficial in improving the outcome. Additionally, hemodialysis
Hemodialysis
In medicine, hemodialysis is a method for removing waste products such as creatinine and urea, as well as free water from the blood when the kidneys are in renal failure. Hemodialysis is one of three renal replacement therapies .Hemodialysis can be an outpatient or inpatient therapy...
can be used for patients with compromised renal function or renal failure.
Paxillus involutus also contains agents which appear to damage chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
s; it is unclear whether these have carcinogen
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...
ic or mutagen
Mutagen
In genetics, a mutagen is a physical or chemical agent that changes the genetic material, usually DNA, of an organism and thus increases the frequency of mutations above the natural background level. As many mutations cause cancer, mutagens are therefore also likely to be carcinogens...
ic potential. Two compounds that have been identified are the phenols
Natural phenol
Natural phenols, bioavailable phenols, plant phenolics, low molecular weight phenols or phenoloids are a class of natural products. They are small molecules containing one or more phenolic group. These molecules are smaller in size than polyphenols, containing less than 12 phenolic groups...
involutone and involutin; the latter is responsible for the brownish discolouration upon bruising.