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Ergot
Claviceps purpurea
Scientific classification
Kingdom: Fungi
Division: Ascomycota
Class: Sordariomycetes
Order: Hypocreales
Family: Clavicipitaceae
Genus: Claviceps
Species

About 50, including:
Claviceps africana
Claviceps fusiformis
Claviceps paspali
Claviceps purpurea

Ergot refers to a group of fungi of the genus Claviceps (ergot fungi).[1] The most prominent member of this group is Claviceps purpurea. This fungus grows on rye and related plants, and produces alkaloids that can cause ergotism in humans and other mammals, consuming grains contaminated with the fruiting structure (called ergot sclerotium) of this fungus.[2][3] There are about 50 known species of Claviceps, most of them in the tropical regions. Economically important species are C. purpurea (parasitic on grasses and cereals), C. fusiformis (on pearl millet, buffel grass), C. paspali (on dallis grass), and C. africana[4](on sorghum). C. purpurea most commonly affects outcrossing species such as rye (its most common host), as well as triticale, wheat and barley. It affects oats only rarely.

There are at least three races or varieties of C. purpurea, differing in their host specificity:[5]

  • G1 — land grasses of open meadows and fields;
  • G2 — grasses from moist, forest, and mountain habitats;
  • G3 (C. purpurea var. spartinae) — salt marsh grasses (Spartina, Distichlis).

Contents

Life cycle

An ergot kernel called a sclerotium develops when a floret of flowering grass or cereal is infected by a spore of fungal species of the genus Claviceps. The infection process mimics a pollen grain growing into an ovary during fertilization. Because infection requires access of the fungal spore to the stigma, plants infected by Claviceps are mainly outcrossing species with open flowers, such as rye (Secale cereale) and ryegrasses (genus Lolium). The proliferating fungal mycelium then destroys the plant ovary and connects with the vascular bundle originally intended for seed nutrition. The first stage of ergot infection manifests itself as a white soft tissue (known as sphacelia) producing sugary honeydew, which often drops out of the infected grass florets. This honeydew contains millions of asexual spores (conidia) which are dispersed to other florets by insects. Later, the sphacelia convert into a hard dry sclerotium inside the husk of the floret. At this stage, alkaloids and lipids accumulate in the sclerotium.

Claviceps species from tropic and subtropic regions produce macro- and microconidia in their honeydew. Macroconidia differ in shape and size between the species, whereas microconidia are rather uniform, oval to globose (5x3μm). Macroconidia are able to produce secondary conidia. A germ tube emerges from a macroconidium through the surface of a honeydew drop and a secondary conidium of the oval to pearlike shape is formed to which the contents of the original macroconidium migrates. Secondary conidia form white frost-like surface on honeydew drops and are spread by wind. No such process occurs in Claviceps purpurea, Claviceps grohii, Claviceps nigricans, and Claviceps zizaniae, all from Northern temperate regions.

When a mature sclerotium drops to the ground, the fungus remains dormant until proper conditions trigger its fruiting phase (onset of spring, rain period, etc.). It germinates, forming one or several fruiting bodies with head and stipe, variously coloured (resembling a tiny mushroom). In the head, threadlike sexual spores are formed, which are ejected simultaneously, when suitable grass hosts are flowering. Ergot infection causes a reduction in the yield and quality of grain and hay produced, and if infected grain or hay is fed to livestock it may cause a disease called ergotism. Black and protruding sclerotia of C. purpurea are well known. However, many tropical ergots have brown or greyish sclerotia, mimicking the shape of the host seed. For this reason, the infection is often overlooked.

Insects, including flies and moths, have been shown to carry conidia of Claviceps species, but it is unknown if insects play a role in spreading the fungus from infected to healthy plants.[6]

Effects on humans and other mammals

Ergot-derived drug to stop postnatal bleeding

The ergot sclerotium contains high concentrations (up to 2% of dry mass) of the alkaloid ergotamine, a complex molecule consisting of a tripeptide-derived cyclol-lactam ring connected via amide linkage to a lysergic acid (ergoline) moiety, and other alkaloids of the ergoline group that are biosynthesized by the fungus.[7] Ergot alkaloids have a wide range of biological activities including effects on circulation and neurotransmission.[8]

Ergotism is the name for sometimes severe pathological syndromes affecting humans or animals that have ingested ergot alkaloid-containing plant material, such as ergot-contaminated grains. The Hospital Brothers of St. Anthony (monks) specialized in treating ergotism victims[9] with balms containing tranquilizing and circulation-stimulating plant extracts; they were also skilled in amputations.[citation needed] The common name for ergotism is "St. Anthony's Fire"[9], in reference to monks who cared for victims as well as symptoms, such as severe burning sensations in the limbs.[10] These are caused by effects of ergot alkaloids on the vascular system due to vasoconstriction of blood vessels, sometimes leading to gangrene and loss of limbs due to severely restricted blood circulation.

The neurotropic activities of the ergot alkaloids may also cause hallucinations and attendant irrational behaviour, convulsions, and even death.[7][8] Other symptoms include strong uterine contractions, nausea, seizures, and unconsciousness. Since the Middle Ages, controlled doses of ergot were used to induce abortions and to stop maternal bleeding after childbirth.[11] Ergot extract has been used in pharmaceutical preparations, including Ergot alkaloids in products such as Cafergot (containing caffeine and ergotamine[11] or ergoline) to treat migraine headaches, and ergometrine, used to induce uterine contractions and to control bleeding after childbirth.[12] In addition to ergot alkaloids, Claviceps paspali also produces tremorgens (paspalitrem) causing "paspalum staggers" in cattle.[citation needed] Ergot alkaloids are also produced by fungi of the genera Penicillium and Aspergillus, notably by some isolates of the human pathogen Aspergillus fumigatus,[13] and have been isolated from plants in the family Convolvulaceae, of which morning glory is best known.

Ergot contains no lysergic acid diethylamide (LSD) but instead contains ergotamine, which is used to synthesize lysergic acid, an analog of and precursor for synthesis of LSD. Moreover, ergot sclerotia naturally contain some amounts of lysergic acid.[14]

In the January 4, 2007 issue of the New England Journal of Medicine, a paper was published documenting a British study of over 11,000 Parkinson's Disease patients. The study found that two ergot-derived drugs, Pergolide and Cabergoline, commonly used to treat Parkinson's Disease may increase the risk of leaky heart valves by up to 700%.[15]

History

Ergot on wheat spikes

Human poisoning due to the consumption of rye bread made from ergot-infected grain was common in Europe in the Middle Ages. The epidemic was known as Saint Anthony's fire[9], or ignis sacer, and some historical events, such as the Great Fear in France during the Revolution have been linked to ergot poisoning.[citation needed] Linnda R. Caporael posited in 1976 that the hysterical symptoms of young women that had spurred the Salem witch trials had been the result of consuming ergot-tainted rye.[16] However, her conclusions were later disputed by Nicholas P. Spanos and Jack Gottlieb, after a review of the historical and medical evidence.[17] Other authors have likewise cast doubt on ergotism having been the cause of the Salem witch trials.[18]

British author John Grigsby claims that the presence of ergot in the stomachs of some of the so called 'bog-bodies' (Iron Age human remains from peat bogs N E Europe such as Tollund Man) is indicative of use of ergot in ritual drinks in a prehistoric fertility cult akin to the Eleusinian Mysteries cult of ancient Greece. In his book Beowulf and Grendel he argues that the Anglo-Saxon poem Beowulf is based on a memory of the quelling of this fertility cult by followers of Odin. He states that Beowulf, which he translates as barley-wolf, suggests a connection to ergot which in German was known as the 'tooth of the wolf'.[citation needed]

Kykeon, the beverage consumed by participants in the ancient Greek cult of Eleusinian Mysteries, might have been based on hallucinogens from ergot,[19] and lysergic acid diethylamide (LSD) is a potent hallucinogen, which was first synthesized from ergot alkaloids by the Swiss chemist, Albert Hofmann, in 1938.

Claviceps purpurea

Claviceps purpurea has been known to mankind for a long time, and its appearance has been linked to extremely cold winters that were followed by rainy summers.[citation needed]

The sclerotial stage of C. purpurea conspicuous on the heads of ryes and other such grains is known as ergot. Favorable temperatures for growth are in the range of 18-30°C, while temperatures above 37°C will cause rapid germination of conidia.[citation needed] Sunlight has a chromogenic effect on the mycelium with intense coloration.[citation needed] Cereal mashes and sprouted rye are suitable substrates for growth of the fungus in the laboratory.[citation needed]

Claviceps africana

Claviceps africana infects sorghum and was first observed in south Texas in 1997.[citation needed] It only infects unfertilized ovaries, so self-pollination and fertilization can decrease the presence of the disease, but male-sterile lines are extremely vulnerable to infection by this fungus.[citation needed] Symptoms of infection by C. africana include the secretion of honeydew (a fluid with high concentrates of sugar and conidia), which attracts insects like flies, beetles, and wasps that feed on it. This in turn contributes to spread of the fungus to uninfected plants.

C. africana caused ergot disease resulting in a famine in 1903-1906 in Northern Cameroon, West Africa, and also occurs in eastern and southern Africa, especially Zimbabwe and South Africa. Male sterile sorghums (also referred to as A-lines) are especially susceptible to infection, first recognized in the 1960s, and massive losses in seed yield have been noted. Infection is associated with cold night temperatures that are below twelve degrees Celsius occurring two to three weeks before flowering.[citation needed]

References

  1. ^ Schardl CL, Panaccione DG, Tudzynski P (2006). "Ergot alkaloids – biology and molecular biology". The Alkaloids: Chemistry and Biology 63: 45–86. doi:10.1016/S1099-4831(06)63002-2. PMID 17133714. 
  2. ^ ergot, online medical dictionary
  3. ^ ergot, Dorland's Medical Dictionary
  4. ^ Bandyopadhyay, Ranajit (1998), "Ergot: A New Disease Threat to Sorghum in the Americas and Australia", Plant Disease 82: 356, doi:10.1094/PDIS.1998.82.4.356, http://www.apsnet.org/online/feature/ergot/0218-01F.pdf 
  5. ^ Sylvie Pazoutova. "Intraspecific variability of C. purpurea". http://www2.biomed.cas.cz/~pazouto/purpurea.htm. 
  6. ^ Butler, M.D., Alderman, S. C., Hammond, P.C., Berry, R. E. (2001). "Association of Insects and Ergot (Claviceps purpurea) in Kentucky Bluegrass Seed Production Fields". J. Econ. Entomol. 94: 1471–1476. doi:10.1603/0022-0493(2001)094[1471:AOIAEC]2.0.CO;2 (inactive 2009-02-19). http://www.bioone.org/doi/full/10.1603/0022-0493(2001)094%5B1471%3AAOIAEC%5D2.0.CO%3B2. 
  7. ^ a b Tudzynski P, Correia T, Keller U (2001). "Biotechnology and genetics of ergot alkaloids". Appl Microbiol Biotechnol. 57: 4593–4605. doi:10.1007/s002530100801. PMID 11778866. 
  8. ^ a b Eadie MJ (2003). "Convulsive ergotism: epidemics of the serotonin syndrome?". Lancet Neurol. 2: 429–434. doi:10.1016/S1474-4422(03)00439-3. PMID 12849122. 
  9. ^ a b c Microbiology in Action. P115. By J. Heritage, Emlyn Glyn Vaughn Evans, R. A. Killington. Cambridge University Press, 1999.
  10. ^ [1]
  11. ^ a b Untersuchungen über das Verhalten der Secalealkaloide bei der Herstellung von Mutterkornextrakten. Labib Farid Nuar. Universität Wien - 1946 - (University of Vienna)
  12. ^ Black, Michael H.; Halmer, Peter (2006). The encyclopedia of seeds: science, technology and uses. Wallingford, UK: CABI. pp. 226. ISBN 978-0-85199-723-0. 
  13. ^ Rao KK, Rao S (1975). "Effect of tweens on the production of ergot alkaloids by Aspergillus fumigatus". Folia Microbiol. 20: 418–422. doi:10.1007/BF02877045. PMID 1104424. 
  14. ^ Correia T, Grammel N, Ortel I, Keller U, Tudzynski P. (2001). "Molecular cloning and analysis of the ergopeptine assembly system in the ergot fungus Claviceps purpurea". Chem Biol. 10: 1281–1292. doi:10.1016/j.chembiol.2003.11.013. PMID 14700635. 
  15. ^ NEJM - Dopamine Agonists and the Risk of Cardiac-Valve Regurgitation
  16. ^ Caporael LR (April 1976). "Ergotism: the satan loosed in Salem?". Science (journal) 192 (4234): 21–6. doi:10.1126/science.769159. PMID 769159. http://web.utk.edu/~kstclair/221/ergotism.html. 
  17. ^ Spanos NP, Gottlieb J (December 1976). "Ergotism and the Salem Village witch trials". Science (journal) 194 (4272): 1390–4. doi:10.1126/science.795029. PMID 795029. 
  18. ^ Woolf A (2000). "Witchcraft or mycotoxin? The Salem witch trials". J Toxicol Clin Toxicol 38: 457–460. doi:10.1081/CLT-100100958. PMID 10930065. 
  19. ^ "Mixing the Kykeon", ELEUSIS: Journal of Psychoactive Plants and Compounds, New Series 4, 2000

External links


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

ERGOT, or Spurred Rye, the drug ergota or Secale cornutum (Ger. Mutterkorn; Fr. seigle ergote), consisting of the sclerotium (or hard resting condition) of a fungus, Claviceps purpurea, parasitic on the pistils of many members of the Grass family, but obtained almost exclusively from rye, Secale cereale. In the ear of rye that is infected with ergot a species of fermentation takes place, and there exudes from it a sweet yellowish mucus, which after a time disappears. The ear loses its starch, and ceases to grow, and its ovaries become penetrated with the white spongy tissue of the mycelium of the fungus which towards the end of the season forms the sclerotium, in which state the fungus lies dormant through the winter.

The drug consists of grains, usually curved (hence the name, from the O. Fr. argot, a cock's spur), which are violet-black or dark-purple externally, and whitish with a tinge of pink within, are between 3 and 12 in. long, and from 1 to 4 lines broad, and have two lateral furrows, a close fracture, a disagreeable rancid taste, and a faint, fishy odour, which last becomes more perceptible when the powder of, the drug is mixed with potash solution. Ergot should be kept in stoppered bottles in order to preserve it from the attacks of a species of mite, and to prevent the oxidation of its fatty oil.

The extremely complex composition of this drug has been studied in great detail, and with such important results that instead of giving ergot itself by the mouth in doses of 20 to 60 grains, it is now possible to obtain much more rapid and certain results by giving one three-hundredth of a grain of one of its constituents hypodermically. This constituent is the alkaloid cornutine, which is the valuable ingredient of the drug. Other ingredients are a fixed oil, present to the extent of 30%, ergotinic acid, a glucoside, trimethylamine, which gives the drug its unpleasant odour, and sphacelinic acid, a non-nitrogenous resinoid body. Of the numerous preparations only two need be mentioned - the liquid extract (dose 10 minims to 2 drachms or more), and the hypodermic injection. The latter does not keep well, and the best way of using ergot is to dissolve tablets obtained from a reputable maker, and containing some of the active principles, in pure water, the solution being injected subcutaneously.

Ergot has no external action. Given internally it stimulates the intestinal muscles and may cause diarrhoea. After absorption it slows the pulse by stimulation of the vagus nerves. It has indeed been asserted that the slow pulse characteristic of the puerperal period is really due to the common administration of ergot at that time. This is probably an exaggeration. The important actions of ergot are on the blood-vessels and the uterus. The drug greatly raises the blood-pressure by causing extreme contraction of the arteries. This is mainly due to a direct action on the muscular coats of the vessels, but is also partly of central origin, since the drug also stimulates the vasomotor centre in the medulla oblongata. This action on the vessels is so marked as to constitute the drug a haemostatic, not only locally but also remotely. It may arrest bleeding from the nose, for instance, when injected hypodermically. Nearly all the constituents share in causing this action, but the sphacelinic acid is probably the most potent. Ergot is the most powerful known stimulant of the pregnant uterus. The action is a double one. At least four of its constituents act directly on the muscular fibre of the uterus, whilst the cornutine acts through the nerves. Of great practical importance is the fact that the cornutine causes rhythmic contractions such as naturally occur, whilst the sphacelinic acid produces a tonic contraction of the uterus, which is unnatural and highly inimical to the life of the foetus. Ergot is used in therapeutics as a haemostatic, and is very valuable in haemoptysis and sometimes in haematemesis. But its great use is in obstetrics. The drug should regularly be given hypodermically, and it is important to note that if the injection be made immediately under the skin, an abscess, or considerable discomfort, may ensue. The injection should be intra-muscular, the needle being boldly plunged into a muscular mass, such as that of the deltoid or the gluteal region. The indications for the use of ergot in obstetrics are highly complex and demand detailed treatment. It can only be said here that the drug should only in the rarest possible cases be given whilst the child is still in utero. This rule is necessitated by the sphacelinic acid, which causes an unnatural state of the organ. When it is possible to obtain pure cornutine, which is unfortunately very expensive, the precautions necessary in other cases may be abrogated.

Chronic poisoning, or ergotism, used frequently to occur amongst the poor fed on rye infected with the Claviceps. As it is practically impossible to reproduce the symptoms of ergotism nowadays, whether experimentally in the lower animals, or when the drug is being administered to a human being for some therapeutic purpose, it is believed that the symptoms of ergotism were rendered possible only by the semi-starvation which must have ensued from the use of such rye-bread; for the grain disappears as the fungus develops. There were two types of ergotism. In the gangrenous form various parts of the body underwent gangrene as a consequence of the arrest of bloodsupply produced by the action of sphacelinic acid on the arteries. In the spasmodic form the symptoms were of a nervous character. The initial indications of the disease were cutaneous itching, tingling and formication, which gave place to actual loss of cutaneous sensation, first observed in the extremities. Amblyopia and some loss of hearing also occurred, as well as mental failure. With weakness of the voluntary muscles went intermittent spasms which weakened the patient and ultimately led to death by implication of the respiratory muscles. The last-known "epidemic" of ergotism occurred in Lorraine and Burgundy in the year 1816.


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