Neurospora
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Neurospora
Shear & B.O. Dodge, 1927
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N. africana |
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Gelasinospora |
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Neurospora is a genus of Ascomycete fungi. The genus name, meaning "nerve spore" refers to the characteristic striations on the spores that resemble axons.
The best known species in this genus is Neurospora crassa, a common model organism in biology. Neurospora intermedia var. oncomensis is believed to be the only mold belonging to Neurospora which is used in food production (to make oncom).[1]
Contents
Characteristics
Neurospora species are molds with broadly spreading colonies, with abundant production of ascomata. Ascomata are superficial or immersed, perithecial and ostiolate or cleistothecial and non-ostiolate, hairy or glabrous, dark coloured. Peridium membranaceous, asci cylindrical, clavate or subspherical, with a persistent or evanescent wall, usually with a thickened and non-amyloid annular structure at the apex, usually 8-spored. Ascospores broadly fusiform, ellipsoidal, or nearly spherical, unicellular, hyaline to yellowish brown or olive-brown, becoming dark and opaque at maturity, ascospore wall with longitudinal ribs or pitted, occasionally nearly smooth, 1–2 (but rarely up to 12) germ pores disposed at the ends of the ascospores, gelatinous sheaths or appendages are absent. Anamorphs are known in only a relatively small number of species, which belong to the fungi imperfecti genus Chrysonilia. The type species of the genus is Neurospora sitophila Shear[2]
Systematics
The former genera Gelasinospora and Neurospora are closely related and not resolved as monophyletic groups,[3] thus the former genus is nowadays included in Neurospora.[4]
Neurospora as model organisms
Neurospora is widely used in genetics as a model organism (especially N. crassa) because it is quickly reproducing, is easy to culture,[5] and can survive on minimal media (inorganic salts, glucose, water and biotin in agar).
The first studies of sexual reproduction in Neurospora were made by B. O. Dodge. Neurospora was later used by George Wells Beadle and Edward Lawrie Tatum in X-ray mutation experiments in order to discover mutants that would differ in nutritional requirements. The results of their experiments led them to the one gene-one enzyme hypothesis, in which they postulated that every enzyme was encoded with its own gene.
Research with Neurospora is reported semi-annually at the Neurospora Meeting at Asilomar, California, coordinated by the Fungal Genetics Stock Center. Mutant and wild-type strains of Neurospora are available from the FGSC. The FGSC also publishes the Fungal Genetics Reports.
Important people in Neurospora research:
- Bernard Ogilvie Dodge (1872–1960)[5]
- George Beadle (Nobel Prize in Physiology or Medicine, 1958)
- Edward Tatum (Nobel Prize in Physiology or Medicine, 1958)
- Esther Lederberg[6][7][8]
- Norman Giles[8]
- David Perkins
- Robert Metzenberg
- Norman Horowitz
- Herschel Mitchell[9]
- Mary B. Mitchell[10]
Sexual reproduction
In the heterothallic species Neurospora crassa, interaction of strains of opposite mating is necessary for the occurrence of sexual reproduction and the production of ascospores by meiosis. The genus Neurospora also includes homothallic species in which a single individual can undergo self-fertilization leading to meiosis and sexual reproduction. Neurospora africana is an example of such a species.[11][12] Because heterothallic species necessarily undergo some degree of outcrossing they may benefit from the masking of deleterious recessive alleles that express in the dikaryon or diploid stage and/or from increased genetic variability. In contrast, homothallic species do not outcross and do not experience these benefits. However, both hetero- and homothallic species derive the benefits of meiosis that include the removal of stress-induced DNA damages by homologous recombinational repair, and the formation of stress-resistant ascospores.
See Also
- Ascomycota
- Ascospore
- Genetic variability
- Heterothallic
- Homologous recombination
- Homothallism
- Mating type
- Meiosis
- Neurospora crassa
References
- ↑ Ho C.C. 1986. Identity and characteristics of Neurospora intermedia responsible for oncom fermentation in Indonesia. Food Microbiology 3(2):115-132 (April 1986).
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- ↑ Zimmer, E. M., August 1946, "MUTANT STRAINS OF NEUROSPORA DEFICIENT IN PARA-AMINOBENZOIC ACID", MA Thesis, Stanford University
- ↑ Hollaender, A., Sansome E. R., Zimmer, E., Demerec, M., April 1945, "Quantitative Irradiation Experiments with Neurospora crassa. II. Ultraviolet Irradiation", American Journal of Botany 32(4):226-235 Also: "Quantitative effects of radiation on mutation production in Neurospora crassa", Records of the Genetics Society of America, Number Thirteen, 1944
- ↑ 8.0 8.1 Giles, N. H. Jr., Lederberg, E. Z., March 1948, "Induced reversions of biochemical mutants in Neurospora crassa", American Journal of Botany 35(3):150-157
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External links
- [1] Fungal Genetics Stock Center
- [2] Neurospora Meeting website
- Neurospora strains at the FGSC
- Neurospora genome projects
- Fungal Cell Biology Group at University of Edinburgh, UK. Website includes many movies and images of Neurospora.
- [3] Fungal Genetics Reports
- [4] Montenegro-Montero A. (2010) "The Almighty Fungi: The Revolutionary Neurospora crassa". A historical view of the many contributions of this organism to molecular biology.
- [5] Neurospora crassa genome
