Afungus is any member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. The Fungi are classified as a kingdom that is separate from plants and animals. The discipline of biology devoted to the study of fungi is known as mycology or fungal biology, which is historically regarded as a branch of botany, even though genetic studies have shown that fungi are more closely related to animals than to plants. Fungi reproduce via spores and grow as hyphae, mycelia, and further specialized structures. Fungal spores are often produced on specialized structures or in fruiting bodies, such as the head of a mushroom. Abundant worldwide, most fungi are mostly invisible to the naked eye because of the small size of their structures, and their cryptic lifestyles in soil, on dead matter, and as symbionts of plants, animals, or other fungi. Fungi perform an essential role in the decomposition of organic matter and have fundamental roles in nutrient cycling and exchange. They have long been used as a direct source of food, such as mushrooms and truffles, as a leavening agent for bread, and in fermentation of various food products, such as wine, beer, and soy sauce.
Since the 1940s, fungi have been used for the production of antibiotics, and, more recently, various enzymes produced by fungi are used industrially and in detergents. Fungi are also used as biological agents to control weeds and pests. Many species produce bioactive compounds called mycotoxins, such as alkaloids and polyketides, that are toxic to animals including humans. The fruiting structures of a few species are consumed recreationally or in traditional ceremonies as a source of psychotropic compounds. Fungi can break down manufactured materials and buildings, and become significant pathogens of humans and other animals. Losses of crops due to fungal diseases or food spoilage can have a large impact on human food supplies and local economies. Despite their importance on human affairs, little is known of the true biodiversity of Kingdom Fungi, which has been estimated at around 1.5 million species, with about 5% of these having been formally classified.
Amanita muscaria, commonly known as the fly agaricorfly Amanita, is a poisonous and psychoactivebasidiomycetefungus, one of many in the genus Amanita. Native throughout the temperate and boreal regions of the Northern Hemisphere, Amanita muscaria has been unintentionally introduced to many countries in the Southern Hemisphere, generally as a symbiont with pine plantations, and is now a true cosmopolitan species. It associates with various deciduous and coniferous trees. The quintessential toadstool, it is a large white-gilled, white-spotted, usually deep red mushroom, one of the most recognizable and widely encountered in popular culture. Several subspecies, with differing cap colour have been recognised to date, including the brown regalis (considered a separate species), the yellow-orange flavivolata, guessowii, and formosa, and the pinkish persicina. Genetic studies published in 2006 and 2008 show several sharply delineated clades which may represent separate species.
Although generally considered poisonous, it has been consumed as a food in parts of Europe, Asia, and North America after parboiling in plentiful water. However, Amanita muscaria is now primarily famed for its hallucinogenic properties with its main psychoactive constituent being the compound muscimol. It was used as an intoxicant and entheogen by the peoples of Siberia and has a religious significance in these cultures. There has been much speculation on traditional use of this mushroom as an intoxicant existed beyond Siberia, however, such traditions are far less well-documented. The American banker and amateur ethnomycologist R. Gordon Wasson proposed the fly agaric was in fact the Soma talked about in the ancient Rig Veda texts of India; although this theory has been refuted by anthropologists, it gained common credence when first published in 1968.
The common name in English is thought to have been derived from its European use as an insecticide, when sprinkled in milk. The fly-killing agent is now known to be ibotenic acid. An alternative derivation proposes that the term fly- refers not to insects as such but rather the delirium resulting from consumption of the fungus. This is based on the medieval belief that flies could enter a person's head and cause mental illness.
Auricularia auricula-judae, known as the Jew's ear, jelly ear or by a number of other common names, is a species of edible Auriculariales mushroom found worldwide. Distinguished by its noticeably ear-like shape and brown colouration, it grows upon wood, especially elder. Its specific name is derived from the belief that Judas Iscariot hung himself from an elder tree; the common name "Judas's ear" eventually became "Jew's ear", while today "jelly ear" or other names are sometimes used. The mushroom can be found throughout the year in Europe, North America, Asia and Australia, where it grows upon both dead and living wood. Although it is not regarded as a choice edible mushroom in the west, it has long been popular in China, to the extent that Australia exported large volumes of the mushroom to China in the early twentieth century.
While not widely consumed in the west, A. auricula-judae was used in folk medicine as recently as the 19th century, for complaints including sore throats, sore eyes and jaundice, and as an astringent. Today, the mushroom is still used for medicinal purposes in China, where soups featuring it are used as a remedy for colds; it is also used in Ghana, as a blood tonic. Modern research into possible medical applications have variously concluded that A. auricula-judae has antitumour, hypoglycemic, anticoagulant and cholesterol-lowering properties.
Image 9Neurospora crassa life cycle. The haploid mycelium reproduces asexually by two processes: (1) simple proliferation of existing mycelium, and (2) formation of conidia (macro- and micro-) which can be dispersed and then germinate to produce new mycelium. In the sexual cycle, mating can only occur between individual strains of different mating type, A and a. Fertilization occurs by the passage of nuclei of conidia or mycelium of one mating type into the protoperithecia of the opposite mating type through the trichogyne. Fusion of the nuclei of opposite mating types occurs within the protoperithecium to form a zygote (2N) nucleus. (from Mating in fungi)
Image 16Amanita muscaria, the most easily recognised "toadstool", is frequently depicted in fairy stories and on greeting cards. It is often associated with gnomes. (from Mushroom)
Parasitic chytrids can transfer material from large inedible phytoplankton to zooplankton. Chytrids zoospores are excellent food for zooplankton in terms of size (2–5 μm in diameter), shape, nutritional quality (rich in polyunsaturated fatty acids and cholesterols). Large colonies of host phytoplankton may also be fragmented by chytrid infections and become edible to zooplankton. (from Marine fungi)
Image 19Young Amanita phalloides "death cap" mushrooms, with a matchbox for size comparison (from Mushroom)
Image 24Chytrid parasites of marine diatoms. (A) Chytrid sporangia on Pleurosigma sp. The white arrow indicates the operculate discharge pore. (B) Rhizoids (white arrow) extending into diatom host. (C) Chlorophyll aggregates localized to infection sites (white arrows). (D and E) Single hosts bearing multiple zoosporangia at different stages of development. The white arrow in panel E highlights branching rhizoids. (F) Endobiotic chytrid-like sporangia within diatom frustule. Bars = 10 μm. (from Marine fungi)
Image 32Agaricus bisporus mushroom is a cultivated edible mushroom for foods and has many names such as "champignon", " button mushroom", "white mushroom", and " portobello" (from Mushroom)
Image 37Close-up cross section of mushroom. (from Mushroom)
Image 38
Mycoloop links between phytoplankton and zooplankton
Chytrid‐mediated trophic links between phytoplankton and zooplankton (mycoloop). While small phytoplankton species can be grazed upon by zooplankton, large phytoplankton species constitute poorly edible or even inedible prey. Chytrid infections on large phytoplankton can induce changes in palatability, as a result of host aggregation (reduced edibility) or mechanistic fragmentation of cells or filaments (increased palatability). First, chytrid parasites extract and repack nutrients and energy from their hosts in form of readily edible zoospores. Second, infected and fragmented hosts including attached sporangia can also be ingested by grazers (i.e. concomitant predation). (from Marine fungi)
Image 39Common puffball (Lycoperdon perlatum) has a glebal hymenium; the interior is white when it is young, but as it matures, the interior becomes brown containing spores (from Mushroom)
Image 40There are over 100 psychoactive mushroom species of genus Psilocybe native to regions all around the world. (from Mushroom)
![Image 36Pennate diatom from an Arctic meltpond, infected with two chytrid-like [zoo-]sporangium fungal pathogens (in false-colour red). Scale bar = 10 μm. (from Marine fungi)](http://en.wikipedia.org/wiki/File:Pennate_diatom_infected_with_two_chytrid-like_fungal_pathogens.png)
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