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  1. List of country calling codes - Wikipedia

    en.wikipedia.org/wiki/International_telephone_codes

    Country calling codes or country dial-in codes are telephone number prefixes for reaching telephone subscribers in the networks of the member countries or regions of the International Telecommunication Union (ITU). The codes are defined by the ...

  2. Lactobacillus - Wikipedia

    en.wikipedia.org/wiki/Lactobacillus
    • Metabolism
    • Genomes
    • Taxonomy
    • Human Health
    • Food Production
    • See Also
    • External Links

    Lactobacilli are homofermentative, i.e. hexoses are metabolised by Glycolysis to lactate as major end product, or heterofermentative, i.e. hexoses are metabolised by the Phosphoketolase pathway to lactate, CO2 and acetate or ethanol as major end products. Most lactobacilli are aerotolerant and some species respire if heme and menaquinone are present in the growth medium. Aerotolerance of lactobacilli is manganese-dependent and has been explored (and explained) in Lactiplantibacillus plantarum (previously Lactobacillus plantarum). Lactobacilli generally do not require ironfor growth. The Lactobacillaceae are the only family of the lactic acid bacteria (LAB) that includes homofermentative and heterofermentative organisms; in the Lactobacillaceae, homofermentative or heterofermentative metabolism is shared by all strains of a genus. Lactobacillus species are all homofermentative, do not express pyruvate formate lyase, and most species do not ferment pentoses. In L. crispatus, pentose m...

    The genomes of lactobacilli are highly variable, ranging in size from 1.2 to 4.9 Mb (megabases). Accordingly, the number of protein-coding genes ranges from 1,267 to about 4,758 genes (in Fructilactobacillus sanfranciscensis and Lentilactobacillus parakefiri, respectively). Even within a single species there can be substantial variation. For instance, strains of L. crispatus have genome sizes ranging from 1.83 to 2.7 Mb, or 1,839 to 2,688 open reading frames. Lactobacillus contains a wealth of compound microsatellites in the coding region of the genome, which are imperfect and have variant motifs.Many lactobacilli also contain multiple plasmids. A recent study has revealed that plasmids encode the genes which are required for adaptation of lactobacilli to the given environment.

    The genus Lactobacillus currently contains 44 species which are adapted to vertebrate hosts or to insects. In recent years, other members of the genus Lactobacillus (formerly known as the Leuconostoc branch of Lactobacillus) have been reclassified into the genera Atopobium, Carnobacterium, Weissella, Oenococcus, and Leuconostoc. The Pediococcus species P. dextrinicus has been reclassified as a Lapidilactobacillus dextrinicus and most lactobacilli were assigned to Paralactobacillus or one of the 23 novel genera of the Lactobacillaceae. Two websites inform on the assignment of species to the novel genera or species (http://www.lactobacillus.uantwerpen.be/; http://www.lactobacillus.ualberta.ca/).

    Vaginal tract

    The female genital tract is one of the principal colonisation sites for human microbiota, and there is interest in the relationship between the composition of these bacteria and human health, with a domination by a single species being correlated with general welfare and good outcomes in pregnancy. In around 70% of women, a Lactobacillusspecies is dominant, although that has been found to vary between American women of European origin and those of African origin, the latter group tending to h...

    Interactions with other pathogens

    Lactobacilli produce hydrogen peroxide which inhibits the growth and virulence of the fungal pathogen Candida albicans in vitro and in vivo. In vitro studies have also shown that lactobacilli reduce the pathogenicity of C. albicans through the production of organic acids and certain metabolites. Both the presence of metabolites, such as sodium butyrate, and the decrease in environmental pH caused by the organic acids reduce the growth of hyphae in C. albicans, which reduces its pathogenicity....

    Probiotics

    Fermentive bacteria like lactic acid bacteria (LAB) produce hydrogen peroxide which protects themselves from oxygen toxicity. The accumulation of hydrogen peroxide in growth media, and its antagonistic effects on Staphylococcus aureus and Pseudomonas, have been demonstrated by researchers. LAB cultures have been used as starter cultures to create fermented foods since the beginning of the 20th century. Elie Metchnikoffwon a nobel prize in 1908 for his work on LAB. Lactobacilli administered in...

    Lactobacilli comprise most food fermenting lactic acid bacteria and are used as starter cultures in industry for controlled fermentation in the production of wine, yogurt, cheese, sauerkraut, pickles, beer, cider, kimchi, cocoa, kefir, and other fermented foods, as well as animal feeds and the bokashi soil amendment. Lactobacillus species are dominant in yoghurt, cheese, and sourdough fermentations.The antibacterial and antifungal activity of lactobacilli relies on production of bacteriocins and low molecular weight compounds that inhibits these microorganisms. Sourdough bread is made either spontaneously, by taking advantage of the bacteria naturally present in flour, or by using a "starter culture", which is a symbiotic culture of yeast and lactic acid bacteria growing in a water and flour medium.The bacteria metabolize sugars into lactic acid, which lowers the pH of their environment, creating a signature "sourness" associated with yogurt, sauerkraut, etc. In many traditional pic...

    Data related to Lactobacillusat Wikispecies
    Lactobacillus at BacDive- the Bacterial Diversity Metadatabase
  3. Papaver somniferum - Wikipedia

    en.wikipedia.org/wiki/Papaver_somniferum
    • Description
    • Distribution
    • History
    • Metabolism
    • Uses
    • Market
    • Cultivation
    • Diseases
    • Restrictions
    • Bibliography

    Papaver somniferum is an annual herb growing to about 100 cm (40 in) tall. The plant is strongly glaucous, giving a greyish-green appearance, and the stem and leaves bear a sparse distribution of coarse hairs. The large leaves are lobed, the upper stem leaves clasping the stem, the lowest leaves with a short petiole.:40 The flowers are up to 30–100 mm (1–4 in) diameter, normally with four white, mauve or red petals, sometimes with dark markings at the base. The fruit is a hairless, rounded capsule topped with 12–18 radiating stigmatic rays, or fluted cap. All parts of the plant exude white latex when wounded.:93:32 In Australia, plant density for optimal cultivation is about 800,000 per hectare. Papaver somniferum was formally described by the Swedish botanist Carl Linnaeus in his seminal publication Species Plantarumin 1753 on page 508.

    The native range of opium poppy is probably the Eastern Mediterranean, but extensive cultivation and introduction of the species throughout Europe since ancient times have obscured its origin. It has escaped from cultivation, or has been introduced and become naturalized extensively in all regions of the British Isles, particularly in the south and eastand in almost all other countries of the world with suitable, temperate climates.

    Use of the opium poppy predates written history. The making and use of opium was known to the ancient Minoans. Its sap was later named opion by the ancient Greeks, from where it gained its modern name of opium. Evidence of the early domestication of opium poppy has been discovered through small botanical remains found in regions of the Mediterranean and west of the Rhine, predating circa 5000 BCE.These samples found in various Neolithic sites show the incredibly early cultivation and natural spread of the plant throughout western Europe. Opium was used for treating asthma, stomach illnesses, and bad eyesight. Opium became a major colonial commodity, moving legally and illegally through trade networks on the Indian subcontinent, Colonial America, Qing China and others. Members of the East India Company saw the opium trade as an investment opportunity beginning in 1683. In 1773, the Governor of Bengal established a monopoly on the production of Bengal opium, on behalf of the East Indi...

    The alkaloids are organic nitrogenous compounds, derivatives of secondary metabolism, synthesized through the metabolic pathway of benzylisoquinoline. First, the amino acid phenylalanine, through the enzyme phenylalanine hydroxylase, is transformed into tyrosine. Tyrosine can follow two different routes: by tyrosine hydroxylase it can form L-dopamine(L-DOPA), or it can be reduced to form 4-phenylhydroxyacetaldehyde (4-HPAA). Subsequently, L-DOPA reacts with 4-HPAA and, through a series of reactions, forms (S) -norcoclaurine, which carries the benzylisoquinoline skeleton that gives its name to this pathway. The conversion of (S) -norcoclaurin to (S) -reticulin is one of the key points, since from (S) -reticulin morphine can be formed through the morphinan route, noscapine through the path of the noscapina or berberina.

    Poppy seeds and oil

    Poppy seeds from Papaver somniferum are an important food item and the source of poppyseed oil, an edible oil that has many uses. The seeds contain very low levels of opiates and the oil extracted from them contains even less.Both the oil and the seed residue also have commercial uses. The poppy press cake as a residue of the oil pressing can be used as fodder for different animals as e.g., poultry and fancy fowls. Especially in the time of the molt of the birds, the cake is nutritive and fit...

    Opiates

    The opium poppy, as its name indicates, is the principal source of opium, the dried latex produced by the seed pods. Opium contains a class of naturally occurring alkaloids known as opiates, that include morphine, codeine, thebaine, oripavine, papaverine and noscapine. The specific epithet somniferum means "sleep-bringing", referring to the sedativeproperties of some of these opiates. The opiate drugs are extracted from opium. The latex oozes from incisions made on the green seed pods and is...

    Ornamental cultivation

    Live plants and seeds of the opium poppy are widely sold by seed companies and nurseries in most of the western world, including the United States. Poppies are sought after by gardeners for the vivid coloration of the blooms, the hardiness and reliability of the poppy plants, the exotic chocolate-vegetal fragrance note of some cultivars,[which?]and the ease of growing the plants from purchased flats of seedlings or by direct sowing of the seed. Poppy seed pods are also sold for dried flower a...

    Food

    In 2018, world production of poppy seeds for consumption was 76,240 tonnes, led by the Turkey with 35% of the world total (table). Poppy seed production and trade are susceptible to fluctuations mainly due to unstable yields. The performance of most genotypes of "Papaver somniferum" is very susceptible to environmental changes This behaviour led to a stagnation of the poppy seed market value between 2008–2009 as a consequence of high stock levels, bad weather and poor quality. The world leadi...

    Medicine

    Australia (Tasmania), Turkey and India are the major producers of poppy for medicinal purposes and poppy-based drugs, such as morphine or codeine. The New York Times reported, in 2014, that Tasmania was the largest producer of the poppy cultivars used for thebaine (85% of the world's supply) and oripavine(100% of the world's supply) production. Tasmania also had 25% of the world's opium and codeine production.

    In the growth development of Papaver somniferum six stages can be distinguished. The growth development starts with the growth of the seedlings. In a second step the rosette-type leaves and stalks are formed. After that budding (hook stage) takes place as a third step. The hook stage is followed by flowering. Subsequently, technical maturity is reached, which means that the plant is ready for cutting. The last step is biological maturity; dry seeds are ripened. The photoperiod seems to be the main determinant of flower development of Papaver somniferum. Papaver somniferum shows a very slow development in the beginning of its vegetation period. Due to this fact the competition of weeds is very high in early stages. It is very important to control weeds effectively in the first 50 days after sowing. Additionally Papaver somniferum is rather susceptible to herbicides. The pre-emergence application of the herbicide chlortoluron has been shown to be effective in reducing weed levels. How...

    Papaver somniferum is susceptible to several fungal, insect and virus infections including seed borne diseases such as downy mildew and root rot. The use of pesticides in combination to cultural methodshave been considered as major control measures for various poppy diseases. The fungal pathogen Peronospora arborescensis, the causal agent of downy mildew, occurs preferentially during wet and humid conditions. This oomycete penetrates the roots through oospores and infects the leaves as conidia in a secondary infection. The fungus causes hypertrophy and curvature of the stem and flower stalks. The symptoms are chlorosis and curling of the affected tissues with necrotic spots. The leaf under-surface is covered with a downy mildew coating containing conidiospores that spread the infection further leading to plant damage and death. Another downy mildew species, Peronospora somniferi, produces systemic infections leading to stunting and deformation of poppy plants.Downy mildew can be con...

    In most of Central Europe, poppyseed is commonly used for traditional pastries and cakes, and it is legal to grow poppies throughout the region, although Germany requires a license. Since January 1999 in the Czech Republic, according to the 167/1998 Sb. Addictive Substances Act, poppies growing in fields larger than 100 square metres (120 sq yd) is obliged for reporting to the local Custom Office. Extraction of opium from the plants is prohibited by law (§ 15 letter d/ of the act). It is also prohibited to grow varieties with more than 0.8% of morphine in dry matter of their capsules, excluding research and experimental purposes (§24/1b/ of the act). The name Czech blue poppy refers to blue poppy seeds used for food.[citation needed] The United Kingdom does not require a license for opium poppy cultivation, but does for extracting opium for medicinal products. In the United States, opium poppies and poppy straw are prohibited. As the opium poppy is legal for culinary or esthetic rea...

  4. Bharal - Wikipedia

    en.wikipedia.org/wiki/Naur
    • Description
    • Taxonomy and Evolution
    • Behaviour and Ecology
    • Threats
    • Relationship with Humans
    • Further Reading
    • External Links

    These medium-sized caprids are 115 to 165 cm (45 to 65 in) long along the head-and-body, with a tail of 10 to 20 cm (3.9 to 7.9 in). They stand 69 to 91 cm (27 to 36 in) high at the shoulder. Body mass can range from 35 to 75 kg (77 to 165 lb). Males are slightly larger than females. Dense coat is slate grey in colour, sometimes with a bluish sheen. The underparts and backs of the legs are white, while the chest and fronts of the legs are black. Separating the grey back and white belly is a charcoal-colored stripe. The ears are small, and the bridge of the nose is dark. The horns are found in both sexes and are ridged on the upper surface. In males, they grow upwards, then turn sideways and curve backward, looking somewhat like an upside-down mustache. They may grow to a length of 80 cm (31 in). In females, the horns are much shorter and straighter, growing up to 20 cm (7.9 in) long.

    Chinese blue sheep, Pseudois nayaur szechuanensis
    Himalayan blue sheep, P. n. nayaur
    Helan Shan blue sheep, P. n.ssp.

    Bharal are active throughout the day, alternating between feeding and resting on the grassy mountain slopes. Due to their excellent camouflage and the absence of cover in their environment, bharal remain motionless when approached. Once they have been noticed, however, they scamper up to the precipitous cliffs, where they once again freeze, using camouflage to blend into the rock face. Population densities in Nepal were found to be 0.9–2.7 animals per km2, increasing to a maximum of 10 animals in the winter, as herds congregate in valleys.Bharal are mainly grazers, but during times of scarcity of grass, they switch to browsers, eating herbs and shrubs. A high degree of diet overlap between livestock (especially donkeys) and bharal, together with density-dependent forage limitation, results in resource competition and a decline in bharal density. Where they overlap, they are the favored prey of snow leopards, Himalayan wolves, and leopards, with a few lambs falling prey to foxes or e...

    The bharal is categorised as least concern by the International Union for Conservation of Nature and Natural Resources. The population faces threats - poaching for meat and competition with livestock. Poaching, however, is uncommon due to the unsuitable conditions of its habitat. Similarly, livestock do not generally frequent the mountainous regions where bharal occur; even if they do coexist, no notable detrimental effect on the bharal has been observed.

    Many Buddhist monasteries protect the bharal found around them, but lately, issues of crop damage caused by bharal have started to arise in areas such as the Spiti Valley.

    Namgail, T., Fox, J.L. & Bhatnagar, Y.V. (2004). Habitat segregation between sympatric Tibetan argali Ovis ammon hodgsoni and blue sheep Pseudois nayaur in the Indian Trans-Himalaya. Journal of Zoo...
    Namgail, T., van Wieren, S.E., Mishra, C. & Prins, H.H.T. (2010). Multi-spatial co-distribution of the endangered Ladakh urial and blue sheep in the arid Trans-Himalayan Mountains. Journal of Arid...
    Namgail, T., Mishra, C., de Jong, C. B., van Wieren, S.E. & Prins, H.H.T. (2009). Effects of herbivore species richness on blue sheep niche dynamics and distribution in the Indian Trans-Himalaya. D...
    Namgail, T. (2001). Habitat Selection and Ecological Separation Between Sympatric Tibetan Argali Blue Sheep in Northern India. University of Tromso, Norway.
  5. SSR1 - Wikipedia

    en.wikipedia.org/wiki/SSR1

    Translocon-associated protein subunit alpha is a protein that in humans is encoded by the SSR1 gene.[5] The signal sequence receptor (SSR) is a glycosylated endoplasmic reticulum (ER) membrane receptor associated with protein translocation ...

  6. Parasitic capacitance - Wikipedia

    en.wikipedia.org/wiki/Parasitic_capacitance
    • Description
    • Effects
    • See Also

    When two conductors at different potentials are close to one another, they are affected by each other's electric field and store opposite electric charges like a capacitor. Changing the potential v between the conductors requires a current iinto or out of the conductors to charge or discharge them. 1. i = C d v d t {\\displaystyle i=C{\\frac {dv}{dt}}\\,} where C is the capacitance between the conductors. For example, an inductor often acts as though it includes a parallel capacitor, because of its closely spaced windings. When a potential difference exists across the coil, wires lying adjacent to each other are at different potentials. They act like the plates of a capacitor, and store charge. Any change in the voltage across the coil requires extra currentto charge and discharge these small 'capacitors'. When the voltage changes only slowly, as in low-frequency circuits, the extra current is usually negligible, but when the voltage changes quickly the extra current is larger and can...

    At low frequencies parasitic capacitance can usually be ignored, but in high frequency circuits it can be a major problem. In amplifier circuits with extended frequency response, parasitic capacitance between the output and the input can act as a feedback path, causing the circuit to oscillate at high frequency. These unwanted oscillations are called parasitic oscillations. In high frequency amplifiers, parasitic capacitance can combine with stray inductance such as component leads to form resonant circuits, also leading to parasitic oscillations. In all inductors, the parasitic capacitance will resonate with the inductance at some high frequency to make the inductor self-resonant; this is called the self-resonant frequency. Above this frequency, the inductor actually has capacitive reactance. The capacitance of the load circuit attached to the output of op amps can reduce their bandwidth. High-frequency circuits require special design techniques such as careful separation of wires...

  7. Henry's pocket - Wikipedia

    en.wikipedia.org/wiki/Henry's_pocket

    Henry's pocket. In animal anatomy, Henry's pocket, more formally known as a cutaneous marginal pouch, is a fold of skin forming an open pouch on the lower posterior part of the external ear. The pocket is situated in the approximate ...

  8. Kuznets curve - Wikipedia

    en.wikipedia.org/wiki/Environmental_Kuznets_Curves
    • Kuznets Ratio
    • Criticisms
    • Kuznets' Own Caveats
    • Inequality and Trade Liberalization
    • Environmental Kuznets Curve
    • See Also
    • Bibliography
    • External Links

    The Kuznets ratio is a measurement of the ratio of income going to the highest-earning households (usually defined by the upper 20%) and the income going to the lowest-earning households,which is commonly measured by either the lowest 20% or lowest 40% of income. Comparing 20% to 20%, a completely even distribution is expressed as 1; 20% to 40% changes this value to 0.5. Kuznets had two similar explanations for this historical phenomenon: 1. workers migrated from agriculture to industry; and 2. rural workers moved to urban jobs. In both explanations, inequality will decrease after 50% of the shift force switches over to the higher paying sector.

    Critics of the Kuznets curve theory argue that its U-shape comes not from progression in the development of individual countries, but rather from historical differences between countries. For instance, many of the middle income countries used in Kuznets' data set were in Latin America, a region with historically high levels of inequality. When controlling for this variable, the U-shape of the curve tends to disappear (e.g. Deininger and Squire, 1998). Regarding the empirical evidence, based on large panels of countries or time series approaches, Fields (2001) considers the Kuznets hypothesis refuted. The East Asian miracle (EAM) has been used to criticize the validity of the Kuznets curve theory. The rapid economic growth of eight East Asian countries—Japan, South Korea, China, Singapore (Four Asian Tigers), Indonesia, Thailand, and Malaysia—between 1965 and 1990, was called the East Asian miracle. Manufacturing and export grew quickly and powerfully. Yet simultaneously, life expect...

    In a biography about Simon Kuznets' scientific methods, economist Robert Fogelnoted Kuznets' own reservations about the "fragility of the data" which underpinned the hypothesis. Fogel notes that most of Kuznets' paper was devoted to explicating the conflicting factors at play. Fogel emphasized Kuznets' opinion that "even if the data turned out to be valid, they pertained to an extremely limited period of time and to exceptional historical experiences." Fogel noted that despite these "repeated warnings", Kuznets' caveats were overlooked, and the Kuznets curve was "raised to the level of law" by other economists.

    Dobson and Ramlogan’s research looked to identify the relationship between inequality and trade liberalization. There have been mixed findings with this idea – some developing countries have experienced greater inequality, less inequality, or no difference at all, due to trade liberalization. Because of this, Dobson and Ramlogan suggest that perhaps trade openness can be related to inequality through a Kuznets curve framework. A trade liberalization-versus-inequality graph measures trade openness along the x-axis and inequality along the y-axis. Dobson and Ramlogan determine trade openness by the ratio of exports and imports (the total trade) and the average tariff rate; inequality is determined by gross primary school enrolment rates, the share of agriculture in total output, the rate of inflation, and cumulative privatization. By studying data from several Latin American countries that have implemented trade liberalization policies in the past 30 years, the Kuznets curve seems to...

    The environmental Kuznets curve (EKC) is a hypothesized relationship between environmental quality and economic development: various indicators of environmental degradation tend to get worse as modern economic growth occurs until average income reaches a certain point over the course of development.The EKC suggests, in sum, that "the solution to pollution is economic growth." Although subject to continuing debate, there is considerable evidence to support the application of environmental Kuznets curve for various environmental health indicators, such as water, air pollution and ecological footprint which show the inverted U-shaped curve as per capita income and/or GDP rise. It has been argued that this trend occurs in the level of many of the environmental pollutants, such as sulfur dioxide, nitrogen oxide, lead, DDT, chlorofluorocarbons, sewage, and other chemicals previously released directly into the air or water. For example, between 1970 and 2006, the United States' inflation-a...

    Brenner, Y.S., Hartmut Kaelble, and Mark Thomas (1991): Income Distribution in Historical Perspective. Cambridge University Press.
    Costantini, V.; Monni, S. (2008). "Environment, Human Development and Economic Growth" (PDF). Ecological Economics. 64 (4): 867–880. doi:10.1016/j.ecolecon.2007.05.011. hdl:10419/73989.
    Dasgupta, S.; Laplante, B.; Wang, H.; Wheeler, D. (2002). "Confronting the Environmental Kuznets Curve". The Journal of Economic Perspectives. 16 (1): 147–168. CiteSeerX 10.1.1.127.3264. doi:10.125...
    Deacon, R. T.; Norman, C. S. (2006). "Does the Environmental Kuznets Curve Describe How Individual Countries Behave?". Land Economics. 82 (2): 291–315. doi:10.3368/le.82.2.291.

    John Tierney (20 April 2009). "Use Energy, Get Rich and Save the Planet". New York Times. Includes links to Further reading:

  9. Caviphantes - Wikipedia

    en.wikipedia.org/wiki/Caviphantes

    Caviphantes is a genus of dwarf spiders that was first described by R. Oi in 1960. Species As of May 2019 it contains five species: Caviphantes dobrogicus (Dumitrescu & Miller, 1962) – Romania to Central Asia Caviphantes flagellatus (Zhu ...

  10. Mating of yeast - Wikipedia

    en.wikipedia.org/wiki/Mating_of_yeast
    • Mating Type and The Life Cycle of Saccharomyces cerevisiae
    • Decision to Mate
    • Mating Type Switching
    • Mating and Inbreeding
    • in Other Yeasts
    • References
    • External Links

    S. cerevisiae (yeast) can stably exist as either a diploid or a haploid. Both haploid and diploid yeast cells reproduce by mitosis, with daughter cells budding off of mother cells. Haploid cells are capable of mating with other haploid cells of the opposite mating type (an a cell can only mate with an α cell, and vice versa) to produce a stable diploid cell. Diploid cells, usually upon facing stressful conditions such as nutrient depletion, can undergo meiosis to produce four haploid spores: two a spores and two α spores.

    Mating in yeast is stimulated by the presence of a pheromone which binds to either the Ste2 receptor (in a-cells) or the Ste3 receptor (in α-cells). The binding of this pheromone then leads to the activation of a heterotrimeric G protein. The dimeric portion of this G-protein recruits Ste5 (and its related MAPK cascade components) to the membrane, and ultimately results in the phosphorylation of Fus3. The switching mechanism arises as a result of competition between the Fus3 protein (a MAPK protein) and the phosphatase Ptc1. These proteins both attempt to control the 4 phosphorylation sites of Ste5, a scaffold proteinwith Fus3 attempting to phosphorylate the phosphosites, and Ptc1 attempting to dephosphorylate them. Presence of α-factor induces recruitment of Ptc1 to Ste5 via a 4 amino acid motif located within the Ste5 phosphosites. Ptc1 then dephosphorylates Ste5, ultimately resulting in the dissociation of the Fus3-Ste5 complex. Fus3 dissociates in a switch-like manner, dependent...

    Wild type haploid yeast are capable of switching mating type between a and α. Consequently, even if a single haploid cell of a given mating type founds a colony of yeast, mating type switching will cause cells of both a and α mating types to be present in the population. Combined with the strong drive for haploid cells to mate with cells of the opposite mating type and form diploids, mating type switching and consequent mating will cause the majority of cells in a colony to be diploid, regardless of whether a haploid or diploid cell founded the colony. The vast majority of yeast strains studied in laboratories have been altered such that they cannot perform mating type switching (by deletion of the HO gene; see below); this allows the stable propagation of haploid yeast, as haploid cells of the a mating type will remain acells (and α cells will remain α cells), and will not form diploids.

    Ruderfer et al. analyzed the ancestry of natural S. cerevisiae strains and concluded that matings involving out-crossing occur only about once every 50,000 cell divisions. Thus it appears that, in nature, mating is most often between closely related yeast cells. Mating occurs when haploid cells of opposite mating type MATa and MATα come into contact. Ruderfer et al. pointed out that such contacts are frequent between closely related yeast cells for two reasons. The first is that cells of opposite mating type are present together in the same ascus, the sac that contains the cells directly produced by a single meiosis, and these cells can mate with each other. The second reason is that haploid cells of one mating type, upon cell division, often produce cells of the opposite mating type with which they can mate (see section "Mating type switching", above). The relative rarity in nature of meiotic events that result from out-crossing appears to be inconsistent with the idea that product...

    Fission yeast

    Schizosaccharomyces pombe is a facultative sexual yeast that can undergo mating when nutrients are limiting. Exposure of S. pombe to hydrogen peroxide, an agent that causes oxidative stress leading to oxidative DNA damage, strongly induces mating, meiosis, and formation of meiotic spores. This finding suggests that meiosis, and particularly meiotic recombination, may be an adaptation for repairing DNA damage. The overall structure of the MAT locus is similar to that in S. cerevisiae. The mati...

    Self-mating in Cryptococcus neoformans

    Cryptococcus neoformans is a basidiomycetous fungus that grows as a budding yeast in culture and in an infected host. C. neoformans causes life-threatening meningoencephalitis in immune compromised patients. It undergoes a filamentous transition during the sexual cycle to produce spores, the suspected infectious agent. The vast majority of environmental and clinical isolates of C. neoformans are mating type α. Filaments ordinarily have haploid nuclei, but these can undergo a process of diploi...

    Matthew P Scott; Paul Matsudaira; Harvey Lodish; James Darnell; Lawrence Zipursky; Chris A Kaiser; Arnold Berk; Monty Krieger (2004). Molecular Cell Biology, Fifth Edition. WH Freeman and Col, NY....
    Malleshaiah, Mk; Shahrezaei, V (2010). "The scaffold protein Ste5 directly controls a switch-like mating decision in yeast". Nature. 465 (7294): 101–5. Bibcode:2010Natur.465..101M. doi:10.1038/natu...
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