Some details and effects of the premeiotic controls of recombination frequencies in Neurospora crossa

SUMMARYRecombination data from crosses made at a single constant temperature of incubation were compared with those from crosses transferred to a different temperature at either the time of conidiation of protoperithecia by the strain of opposite mating-type, or after fertilization when crozier stages were first visible. Results were also compared from reciprocal crosses, from crosses made in different ways and from crosses in which protoperithecia were conidiated at different stages of maturity.Different temperature regimes during vegetative growth and proto-perithecial development had highly significant effects on subsequent meiotic recombination, while temperature differences during later premeiotic stages (between conidiation of protoperithecia and the crozier stage) had no or little effect. It was found that premeiotic controls could have as great, or greater, effects on meiotic recombination than those operating directly during meiosis. The possible adaptive significance of this is discussed.Recombination frequencies were affected by the method of making a cross (joint-inoculation of strains of opposite mating-type, or conidiation of protoperithecia), and by protoperithecial age at the time of conidiation by the opposite mating-type. Differences in recombination between reciprocal crosses were obtained and were dependent on temperature of incubation and age of protoperithecia at the time of conidiation. Recombination was not affected by different lysine concentrations in the medium. Genetic differences in premeiotic effector-production between the strains used were inferred.

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A SUPPRESSOR OF THE HETEROKARYON- INCOMPATIBILITY ASSOCIATED WITH MATING TYPE IN NEUROSPORA CRASSA

Canadian Journal of Genetics and Cytology ◽

10.1139/g70-115 ◽

1970 ◽

Vol 12 (4) ◽

pp. 914-926 ◽

Cited By ~ 52

Author(s):

Dorothy Newmeyer

Keyword(s):

Linkage Group ◽

Neurospora Crassa ◽

Mating Type ◽

Vegetative Growth ◽

Mode Of Action ◽

Wild Strain ◽

Group Iv ◽

Mating Types ◽

Vegetative Incompatibility ◽

Opposite Mating Type

Neurospora crassa strains of opposite mating type are ordinarily heterokaryon-incompatible during vegetative growth. An unlinked mutant called tolerant (tol) is described, which suppresses the vegetative incompatibility of unlike mating types without affecting their ability to cross. The mutant tol was selected and studied by means of duplications heterozygous for mating type. Use of the duplication eliminates complications due to unlinked heterokaryon genes. The mode of action of tol has been confirmed by conventional heterokaryon tests. tol has been mapped in linkage group IV, close to tryp-4. A suppressor similar or identical to tolerant has been found in a wild strain from Panama, out of 14 different wild types which were tested. By using a different duplication which covers the unlinked heterokaryon-compatibility locus C, it was shown that tolerant does not suppress C/c incompatibility. The fact that tolerant suppresses only one of the two functions ascribed to mating type revives the question of whether 'mating-type' is one gene or two. However, the data strongly support Pittenger's (1957) conclusion that, if two genes are involved, they must be closely linked.

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Unisexual reproduction promotes competition for mating partners in the global human fungal pathogenCryptococcus deneoformans

10.1101/523894 ◽

2019 ◽

Author(s):

Ci Fu ◽

Torin P. Thielhelm ◽

Joseph Heitman

Keyword(s):

Mating Type ◽

Meiotic Recombination ◽

Species Complex ◽

Hyphal Growth ◽

Morphological Transition ◽

Pheromone Response ◽

Opposite Mating Type ◽

Pheromone Response Pathway ◽

Pathway Activation ◽

Unisexual Reproduction

AbstractCourtship is pivotal for successful mating. However, courtship is challenging for theCryptococcus neoformansspecies complex, comprised of opportunistic fungal pathogens, as the majority of isolates are α mating type. In the absence of mating partners of the opposite mating type,C. deneoformanscan undergo unisexual reproduction, during which a yeast-to-hyphal morphological transition occurs. Hyphal growth during unisexual reproduction is a quantitative trait, which reflects a strain’s ability to undergo unisexual reproduction. In this study, we determined whether unisexual reproduction confers an ecological benefit by promoting foraging for mating partners. Through competitive mating assays using strains with different abilities to produce hyphae, we showed that unisexual reproduction potential did not enhance competition for mating partners of the same mating type, but when cells of the opposite mating type were present, cells with enhanced hyphal growth were more competitive for mating partners of either the same or opposite mating type. Enhanced mating competition was also observed in a strain with increased hyphal production that lacks the mating repressor geneGPA3, which contributes to the pheromone response. Hyphal growth in unisexual strains also enables contact between adjacent colonies and enhances mating efficiency during mating confrontation assays. The pheromone response pathway activation positively correlated with unisexual reproduction hyphal growth during bisexual mating and exogenous pheromone promoted bisexual cell fusion. Despite the benefit in competing for mating partners, unisexual reproduction conferred a fitness cost. Taken together, these findings suggestC. deneoformansemploys hyphal growth to facilitate contact between colonies at long distances and utilizes pheromone sensing to enhance mating competition.Author SummarySexual reproduction plays a pivotal role in shaping fungal population structure and diversity in nature. The global human fungal pathogenCryptococcus neoformansspecies complex evolved distinct sexual cycles: bisexual reproduction between mating partners of the opposite mating types, and unisexual reproduction with only one mating type. During both sexual cycles, cells undergo a yeast-to-hyphal morphological transition and nuclei diploidize through either cell-cell fusion followed by nuclear fusion during bisexual reproduction or endoreplication during unisexual reproduction. Despite the complex sexual life cycle, the majority of Cryptococcal isolates are α mating type. Albeit the scarcity ofMATacells in the environment, meiotic recombination is prevalent. To decipher this conundrum, we ask whether there is an underlying mechanism in whichCryptococcusspecies increase their mating opportunities. In this study, we showed that the undirected hyphal growth during unisexual reproduction enablesMATα cells to forage for mating partners over a larger surface area, and whenMATα hyphae come into close proximity of rareMATacells, pheromone response pathway activation in bothMATα andMATacells can further enhance mating. This mating enhancement could promote outcrossing and facilitate genome reshuffling via meiotic recombination.

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Molecular Characterization of tol, a Mediator of Mating-Type-Associated Vegetative Incompatibility in Neurospora crassa

Genetics ◽

10.1093/genetics/151.2.545 ◽

1999 ◽

Vol 151 (2) ◽

pp. 545-555 ◽

Cited By ~ 3

Author(s):

Patrick Ka Tai Shiu ◽

N Louise Glass

Keyword(s):

Sexual Reproduction ◽

Neurospora Crassa ◽

Mating Type ◽

Vegetative Growth ◽

Point Mutations ◽

Coiled Coil ◽

Wild Type ◽

Opposite Mating Type ◽

Type Locus

Abstract The mating-type locus in the haploid filamentous fungus, Neurospora crassa, controls mating and sexual development. The fusion of reproductive structures of opposite mating type, A and a, is required to initiate sexual reproduction. However, the fusion of hyphae of opposite mating type during vegetative growth results in growth inhibition and cell death, a process that is mediated by the tol locus. Mutations in tol are recessive and suppress mating-type-associated heterokaryon incompatibility. In this study, we describe the cloning and characterization of tol. The tol gene encodes a putative 1011-amino-acid polypeptide with a coiled-coil domain and a leucine-rich repeat. Both regions are required for tol activity. Repeat-induced point mutations in tol result in mutants that are wild type during vegetative growth and sexual reproduction, but that allow opposite mating-type individuals to form a vigorous heterokaryon. Transcript analyses show that tol mRNA is present during vegetative growth but absent during a cross. These data suggest that tol transcription is repressed to allow the coexistence of opposite mating-type nuclei during the sexual reproductive phase. tol is expressed in a mat A, mat a, A/a partial diploid and in a mating-type deletion strain, indicating that MAT A-1 and MAT a-1 are not absolutely required for transcription or repression of tol. These data suggest that TOL may rather interact with MAT A-1 and/or MAT a-1 (or downstream products) to form a death-triggering complex.

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ESCAPE FROM MATING-TYPE INCOMPATIBILITY IN BISEXUAL (A + a) NEUROSPORA HETEROKARYONS

Canadian Journal of Genetics and Cytology ◽

10.1139/g75-058 ◽

1975 ◽

Vol 17 (3) ◽

pp. 441-449 ◽

Cited By ~ 11

Author(s):

A. M. DeLange ◽

A. J. F. Griffiths

Keyword(s):

Mating Type ◽

Loss Of Function ◽

Wild Type ◽

Opposite Mating Type ◽

Type Locus ◽

Heterokaryon Incompatibility ◽

Recessive Mutant ◽

Type Rate ◽

Wild Type Rate ◽

Incompatibility Locus

In Neurospora crassa, strains of opposite mating type generally do not form stable heterokaryons because the mating type locus acts as a heterokaryon incompatibility locus. However, when one A and one a strain, having complementing auxotrophic mutants, are placed together on minimal medium, growth may occur, although the growth is generally slow. In this study, escape from such slow growth to that at a wild type or near-wild type rate was observed. The escaped cultures are stable heterokaryons, mostly having lost the mating type allele function from one component nucleus, so that the nuclear types are heterokaryon compatible. Either A or a mating type can be lost. This loss of function has been attributed to deletion since only one nuclear type could be recovered in all heterokaryons except one, but deletion spanning adjacent loci has been directly demonstrated in a minority of cases. Alternatively when one component strain is tol and the other tol+ (tol being a recessive mutant suppressing the heterokaryon incompatibility associated with mating type), escape may occur by the deletion or mutation of tol+, also resulting in heterokaryon compatibility. An induction mechanism for escape is speculated upon.

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The cell type ofRhodosporidium toruloides after protoplast fusion between strains of identical and opposite mating type

Current Microbiology ◽

10.1007/bf01567204 ◽

1983 ◽

Vol 9 (5) ◽

pp. 297-300 ◽

Cited By ~ 7

Author(s):

Dietmar Becher ◽

Fritz Böttcher

Keyword(s):

Protoplast Fusion ◽

Mating Type ◽

Cell Type ◽

Opposite Mating Type

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Assessing the role of two populations of Aedes japonicus japonicus for Zika virus transmission under a constant and a fluctuating temperature regime

Parasites & Vectors ◽

10.1186/s13071-020-04361-2 ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Uros Glavinic ◽

Jasmin Varga ◽

Anca Ioana Paslaru ◽

Jeannine Hauri ◽

Paul Torgerson ◽

...

Keyword(s):

Constant Temperature ◽

Temperature Regime ◽

Zika Virus ◽

Incubation Temperature ◽

Transmission Rate ◽

Control Measures ◽

Fluctuating Temperature ◽

Laboratory Conditions ◽

Temperature Regimes ◽

Two Populations

Abstract Background Since the huge epidemic of Zika virus (ZIKV) in Brazil in 2015, questions were raised to understand which mosquito species could transmit the virus. Aedes aegypti has been described as the main vector. However, other Aedes species (e.g. Ae. albopictus and Ae. japonicus) proven to be competent for other flaviviruses (e.g. West Nile, dengue and yellow fever), have been described as potential vectors for ZIKV under laboratory conditions. One of these, the Asian bush mosquito, Ae. japonicus, is widely distributed with high abundances in central-western Europe. In the present study, infection, dissemination and transmission rates of ZIKV (Dak84 strain) in two populations of Ae. japonicus from Switzerland (Zürich) and France (Steinbach, Haut-Rhin) were investigated under constant (27 °C) and fluctuating (14–27 °C, mean 23 °C) temperature regimes. Results The two populations were each able to transmit ZIKV under both temperature regimes. Infectious virus particles were detected in the saliva of females from both populations, regardless of the incubation temperature regime, from 7 days post-exposure to infectious rabbit blood. The highest amount of plaque forming units (PFU) (400/ml) were recorded 14 days post-oral infection in the Swiss population incubated at a constant temperature. No difference in terms of infection, dissemination and transmission rate were found between mosquito populations. Temperature had no effect on infection rate but the fluctuating temperature regime resulted in higher dissemination rates compared to constant temperature, regardless of the population. Finally, transmission efficiency ranged between 7–23% and 7–10% for the constant temperature and 0–10% and 3–27% under fluctuating temperatures for the Swiss and the French populations, respectively. Conclusions To the best of our knowledge, this is the first study confirming vector competence for ZIKV of Ae. japonicus originating from Switzerland and France at realistic summer temperatures under laboratory conditions. Considering the continuous spread of this species in the northern part of Europe and its adaptation at cooler temperatures, preventative control measures should be adopted to prevent possible ZIKV epidemics.

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Hemp Dogbane Growth and Control

Weed Science ◽

10.1017/s0043174500035244 ◽

1972 ◽

Vol 20 (2) ◽

pp. 156-159 ◽

Cited By ~ 11

Author(s):

Laren R. Robison ◽

Larry S. Jeffery

Keyword(s):

Seed Germination ◽

Soil Type ◽

Vegetative Growth ◽

Soil Cover ◽

Seedling Emergence ◽

Control Seed ◽

Cover Soil ◽

And Control ◽

Emergence Response ◽

Made In

Hemp dogbane (Apocynum cannabinum L.) was investigated relative to seed germination, depth of seedling emergence, response to clipping, influence of soil type and fertility on vegetative growth, and herbicidal control. Seed germination in this study was influenced by light and scarification. Seedling emergence was influenced by the amount of soil cover. Soil type and fertility affected vegetative growth. In a greenhouse clipping study, hemp dogbane became perennial 41 days after emergence and by 65 days was producing more than one shoot per plant following clipping. Hemp dogbane was more completely controlled following September application of herbicide than from application made in June.

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Environmental Control of Flowering of Boronia megastigma (Rutaceae) and Hypocalymma angustifolium (Myrtaceae)

Australian Journal of Botany ◽

10.1071/bt9940219 ◽

1994 ◽

Vol 42 (2) ◽

pp. 219 ◽

Cited By ~ 4

Author(s):

JS Day ◽

BR Loveys ◽

D Aspinall

Keyword(s):

Temperature Regime ◽

Flower Development ◽

Vegetative Growth ◽

Environmental Control ◽

Night Temperature ◽

Root Temperature ◽

Aerial Parts ◽

Temperature Regimes ◽

Controlled Flowering

The flowering responses of Boronia megastigma Nees (Rutacae) and Hypocalymma angustifolium Endl. (Myrtaceae) to different photoperiod and temperature regimes were similar despite the fact that these species are from different families. No flowers reached anthesis in a temperature regime of 25°C day/17°C night but flowering of both species occurred in a cool temperatures (17°C day/9°C night). Photoperiod had no effect on flowering at the temperatures tested. Ten weeks of cool temperatures (17°C day/9°C night) were required for a maximum number of flowers to reach anthesis on H. angustifolium plants whereas B. megastigma plants required 15 weeks. Flower development in both species was inhibited by a large difference between day and night temperature (21°C day/5°C night) and promoted if the day/night difference was reversed (9°C day/17°C night). The temperature of the aerial parts of the plant controlled flowering, whereas vegetative growth was controlled by root temperature. Therefore, while a reduction in vegetative growth naturally coincides with the production of flowers, these events are not necessarily linked.

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Self-Aligning Hot-Wire Probe

Journal of the Royal Aeronautical Society ◽

10.1017/s000192400005466x ◽

1967 ◽

Vol 71 (681) ◽

pp. 657-658 ◽

Cited By ~ 3

Author(s):

A. D. Bond ◽

A. M. Porter

Keyword(s):

Constant Temperature ◽

Two Dimensional ◽

Servo Motor ◽

Hot Wire ◽

Turbulence Measurements ◽

Wire Probe ◽

Two Dimensional Flow ◽

The Wire ◽

Single Constant ◽

Stream Direction

Summary:—This note describes how a single constant temperature hot wire may be used for measurements of direction, velocity and turbulence in a two-dimensional flow. The wire probe is rotated by a servo motor which automatically sets the wire with its axis either in the stream direction or normal to the flow. The accuracy of setting the wire in the direction of the stream is about , and across the stream is about 1°. If the higher accuracy is demanded the velocity and turbulence measurements require a second setting of the probe, at 90° to the previous one. When less precision is acceptable, the angle, velocity and turbulence measurements may be taken at the single setting, normal to the stream.

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