Dimorphic fungus

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Candida albicans growing as yeast cells and filamentous (hypha) cells Candida albicans growing as yeast cells and filamentous (hypha) cells.jpg
Candida albicans growing as yeast cells and filamentous (hypha) cells

A dimorphic fungus is a fungus that can exist in the form of both mold [1] and yeast. As this is usually brought about by a change in temperature, this fungus type is also described as a thermally dimorphic fungus. [2] An example is Talaromyces marneffei , [3] a human pathogen that grows as a mold at room temperature, and as a yeast at human body temperature.

Contents

The term dimorphic is commonly used for fungi that can grow both as yeast and filamentous cells, however many of these dimorphic fungi actually can grow in more than these two forms. Dimorphic is thus often used as a general reference for fungi being able to switch between yeast and filamentous cells, but not necessary limiting more shapes. [4] [lower-alpha 1]

Ecology of dimorphic fungi

Several species of dimorphic fungi are important pathogens of humans and other animals, including Coccidioides immitis , [lower-alpha 1] [5] Paracoccidioides brasiliensis , [lower-alpha 1] [5] Candida albicans , [6] [lower-alpha 1] Blastomyces dermatitidis [lower-alpha 1] , [4] Histoplasma capsulatum , [lower-alpha 1] [4] Sporothrix schenckii , [lower-alpha 1] [4] and Emmonsia sp. [7] Some diseases caused by the fungi are:

Many other fungi, including the plant pathogen Ustilago maydis [6] and the cheesemaker's fungus Geotrichum candidum also have dimorphic life cycles.

Mnemonics

In medical mycology, these memory aids help students remember that among human pathogens, dimorphism largely reflects temperature:

Notes

  1. 1 2 3 4 5 6 7 8 e.g. Candida albicans, Paracoccidioides brasiliensis, Sporothrix schenckii, Histoplasma capsulatum and Coccidioides immitis are commonly referred to as being dimorphic, however they can be seen as pleomorphic or polyphenic as they can adopt more morphologies than just yeast or filamentous cells. [8] [4]

Related Research Articles

<span class="mw-page-title-main">Ascomycota</span> Division or phylum of fungi

Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 62,000 species. The defining feature of this fungal group is the "ascus", a microscopic sexual structure in which nonmotile spores, called ascospores, are formed. However, some species of Ascomycota are asexual and thus do not form asci or ascospores. Familiar examples of sac fungi include morels, truffles, brewers' and bakers' yeast, dead man's fingers, and cup fungi. The fungal symbionts in the majority of lichens such as Cladonia belong to the Ascomycota.

<span class="mw-page-title-main">Corn smut</span> Fungal plant disease on maize and teosinte

Corn smut is a plant disease caused by the pathogenic fungus Mycosarcoma maydis. One of several cereal crop pathogens called smut, the fungus forms galls on all above-ground parts of corn species such as maize and teosinte. The infected corn is edible; in Mexico, it is considered a delicacy, called huitlacoche, often eaten as a filling in quesadillas and other tortilla-based dishes, as well as in soups.

<i>Talaromyces marneffei</i> Species of fungus

Talaromyces marneffei, formerly called Penicillium marneffei, was identified in 1956. The organism is endemic to southeast Asia, where it is an important cause of opportunistic infections in those with HIV/AIDS-related immunodeficiency. Incidence of T. marneffei infections has increased due to a rise in HIV infection rates in the region.

<i>Histoplasma</i> Genus of fungi

Histoplasma is a genus of fungi in the order Onygenales. Species are known human pathogens producing yeast-like states under pathogenic conditions. They are the causative agents of histoplasmosis in humans and epizootic lymphangitis in horses.

<i>Histoplasma capsulatum</i> Species of fungus

Histoplasma capsulatum is a species of dimorphic fungus. Its sexual form is called Ajellomyces capsulatus. It can cause pulmonary and disseminated histoplasmosis.

<span class="mw-page-title-main">Echinocandin</span> Group of chemical compounds

Echinocandins are a class of antifungal drugs that inhibit the synthesis of β-glucan in the fungal cell wall via noncompetitive inhibition of the enzyme 1,3-β glucan synthase. The class has been termed the "penicillin of antifungals," along with the related papulacandins, as their mechanism of action resembles that of penicillin in bacteria. β-glucans are carbohydrate polymers that are cross-linked with other fungal cell wall components, the fungal equivalent to bacterial peptidoglycan. Caspofungin, micafungin, and anidulafungin are semisynthetic echinocandin derivatives with limited clinical use due to their solubility, antifungal spectrum, and pharmacokinetic properties.

<i>Paracoccidioides brasiliensis</i> Species of fungus

Paracoccidioides brasiliensis is a dimorphic fungus and one of the two species that cause paracoccidioidomycosis. The fungus has been affiliated with the family Ajellomycetaceae although a sexual state or teleomorph has not yet been found.

<i>Blastomyces dermatitidis</i> Species of fungus

Blastomyces dermatitidis is a dimorphic fungus that causes blastomycosis, an invasive and often serious fungal infection found occasionally in humans and other animals. It lives in soil and wet, decaying wood, often in an area close to a waterway such as a lake, river or stream. Indoor growth may also occur, for example, in accumulated debris in damp sheds or shacks. The fungus is endemic to parts of eastern North America, particularly boreal northern Ontario, southeastern Manitoba, Quebec south of the St. Lawrence River, parts of the U.S. Appalachian mountains and interconnected eastern mountain chains, the west bank of Lake Michigan, the state of Wisconsin, and the entire Mississippi Valley including the valleys of some major tributaries such as the Ohio River. In addition, it occurs rarely in Africa both north and south of the Sahara Desert, as well as in the Arabian Peninsula and the Indian subcontinent. Though it has never been directly observed growing in nature, it is thought to grow there as a cottony white mold, similar to the growth seen in artificial culture at 25 °C (77 °F). In an infected human or animal, however, it converts in growth form and becomes a large-celled budding yeast. Blastomycosis is generally readily treatable with systemic antifungal drugs once it is correctly diagnosed; however, delayed diagnosis is very common except in highly endemic areas.

Pathogenic fungi are fungi that cause disease in humans or other organisms. Although fungi are eukaryotic, many pathogenic fungi are microorganisms. Approximately 300 fungi are known to be pathogenic to humans; their study is called "medical mycology". Fungal infections are estimated to kill more people than either tuberculosis or malaria—about two million people per year.

<span class="mw-page-title-main">Blastoconidium</span>

A blastoconidium is an asexual holoblastic conidia formed through the blowing out or budding process of a yeast cell, which is a type of asexual reproduction that results in a bud arising from a parent cell. The production of a blastoconidium can occur along a true hyphae, pseudohyphae, or a singular yeast cell. The word "conidia" comes from the Greek word konis and eidos, konis meaning dust and eidos meaning like. The term "bud" comes from the Greek word blastos, which means bud. Yeasts such as Candida albicans and Cryptococcus neoformans produce these budded cells known as blastoconidia.

<span class="mw-page-title-main">Fungal meningitis</span> Meningitis caused by a fungal infection

Fungal meningitis refers to meningitis caused by a fungal infection.

<span class="mw-page-title-main">Forensic mycology</span>

Forensic mycology is the use of mycology in criminal investigations. Mycology is used in estimating times of death or events by using known growth rates of fungi, in providing trace evidence, and in locating corpses. It also includes tracking mold growth in buildings, the use of fungi in biological warfare, and the use of psychotropic and toxic fungus varieties as illicit drugs or causes of death.

Emmonsia parva is a filamentous, saprotrophic fungus and one of three species within the genus Emmonsia. The fungus is most known for its causal association with the lung disease, adiaspiromycosis which occurs most commonly in small mammals but is also seen in humans. The disease was first described from rodents in Arizona, and the first human case was reported in France in 1964. Since then, the disease has been reported from Honduras, Brazil, the Czech Republic, Russia, the United States of America and Guatemala. Infections in general are quite rare, especially in humans.

Histoplasma duboisii is a saprotrophic fungus responsible for the invasive infection known as African histoplasmosis. This species is a close relative of Histoplasma capsulatum, the agent of classical histoplasmosis, and the two occur in similar habitats. Histoplasma duboisii is restricted to continental Africa and Madagascar, although scattered reports have arisen from other places usually in individuals with an African travel history. Like, H. capsulatum, H. duboisii is dimorphic – growing as a filamentous fungus at ambient temperature and a yeast at body temperature. It differs morphologically from H. capsulatum by the typical production of a large-celled yeast form. Both agents cause similar forms of disease, although H. duboisii predominantly causes cutaneous and subcutaneous disease in humans and non-human primates. The agent responds to many antifungal drug therapies used to treat serious fungal diseases.

Ustilagic acid is an organic compound with the formula C36H64O18. The acid is a cellobiose lipid produced by the corn smut fungus Ustilago maydis under conditions of nitrogen starvation. The acid was discovered in 1950 and was proved to be an amphipathic glycolipid with surface active properties. The name comes from Latin ustus which means burnt and refers to the scorched appearance of the smut fungi.

<span class="mw-page-title-main">John W. Taylor (professor)</span> American scientist (born 1950)

John Waldo Taylor is an American scientist who researches fungal evolution and ecology. He is professor of the graduate school in the Department of Plant and Microbial Biology at the University of California, Berkeley.

Sporothrix brasiliensis is a fungus that is commonly found in soil. It is an emerging fungal pathogen that is causing disease in humans and cats mainly in Brazil and other countries in South America.

<span class="mw-page-title-main">Libero Ajello</span> American mycologist (1916–2004)

Libero Ajello was an American mycologist. He cofounded and was first president of the International Society of Human and Animal Mycology (ISHAM). He was the head of the Division of Mycotic Diseases at the Communicable Disease Center (CDC), and editor of the ISHAM Journal Medical Mycology for several years. He was one of the first researchers to investigate histoplasmosis and coccidioidomycosis in the United States and made valuable contributions to the comprehensive field of veterinary and human fungal disease diagnosis.

References

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  4. 1 2 3 4 5 Kerridge, D.; Odds, F. C.; Bossche, Hugo Vanden (2012). Dimorphic Fungi in Biology and Medicine. Springer Science & Business Media. ISBN   978-1-4615-2834-0.
  5. 1 2 "Dimorphic Fungi" . Retrieved 2007-08-19.
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  7. Kenyon, Chris; Bonorchis, Kim; Corcoran, Craig; Meintjes, Graeme; Locketz, Michael; Lehloenya, Rannakoe; Vismer, Hester F.; Naicker, Preneshni; Prozesky, Hans; van Wyk, Marelize; Bamford, Colleen; du Plooy, Moira; Imrie, Gail; Dlamini, Sipho; Borman, Andrew M.; Colebunders, Robert; Yansouni, Cedric P.; Mendelson, Marc; Govender, Nelesh P. (2013). "A Dimorphic Fungus Causing Disseminated Infection in South Africa". New England Journal of Medicine. 369 (15): 1416–1424. doi: 10.1056/NEJMoa1215460 . ISSN   0028-4793. PMID   24106934. S2CID   15865.
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