scholarly journals Drivers of Mating Type Composition in Tetrahymena thermophila

2020 ◽  
Vol 12 (12) ◽  
pp. 2328-2343
Author(s):  
Guangying Wang ◽  
Kai Chen ◽  
Jing Zhang ◽  
Shanjun Deng ◽  
Jie Xiong ◽  
...  
Keyword(s):  
Natural Selection ◽  
Mating Type ◽  
Tetrahymena Thermophila ◽  
Evolutionary Strategies ◽  
Whole Genome ◽  
Mating Types ◽  
Type Composition ◽  
Theoretical Predictions ◽  
Single Mating

Abstract Sex offers advantages even in primarily asexual species. Some ciliates appear to utilize such reproductive strategy with many mating types. However, the factors determining the composition of mating types in the unicellular ciliate Tetrahymena thermophila are poorly understood, and this is further complicated by non-Mendelian determination of mating type in the offspring. We therefore developed a novel population genetics model to predict how various factors influence the dynamics of mating type composition, including natural selection. The model predicted either the coexistence of all seven mating types or fixation of a single mating type in a population, depending on parameter combinations, irrespective of natural selection. To understand what factor(s) may be more influential and to test the validity of theoretical prediction, five replicate populations were maintained in laboratory such that several factors could be controlled or measured. Whole-genome sequencing was used to identify newly arising mutations and determine mating type composition. Strikingly, all populations were found to be driven by strong selection on newly arising beneficial mutations to fixation of their carrying mating types, and the trajectories of speed to fixation agreed well with our theoretical predictions. This study illustrates the evolutionary strategies that T. thermophila can utilize to optimize population fitness.

scholarly journals Homotypic pair formation during conjugation in Tetrahymena thermophila

1986 ◽  
Vol 82 (1) ◽  
pp. 223-234
Author(s):  
A. Kitamura ◽  
T. Sugai ◽  
Y. Kitamura
Keyword(s):  
Phospholipase C ◽  
Mating Type ◽  
Tetrahymena Thermophila ◽  
Single Cells ◽  
Initial Step ◽  
Pair Formation ◽  
Mating Types ◽  
Morphological Markers ◽  
Mechanical Separation

In the ciliate Tetrahymena thermophila, conjugation has been believed to occur only between cells of different mating types. We found the formation of homotypic pairs during normal conjugation by using micronuclear morphological markers. Homotypic pairs formed preferentially during the first 10 min following the first pair formation and comprised about half of the pairs. These results suggest the involvement of mating-type non-specific adhesion of cells in the initial step of conjugation. Homotypic pairs apparently persist for at least 30 min and then separate into single cells. Homotypic pairs are also formed when conjugant pairs re-form after mechanical separation of heterotypic pairs. Five kinds of glycosidases, three kinds of proteases and phospholipase C showed no effect on either the formation of homotypic pairs of their separation. The relation between the mating-type substances and the molecules responsible for mating-type non-specific adhesion of cells is discussed.

Control of sexuality in Phytophthora cinnamomi

1974 ◽  
Vol 22 (4) ◽  
pp. 669 ◽  
Author(s):  
ST Chang ◽  
CJ Shepherd ◽  
BH Pratt
Keyword(s):  
Mating Type ◽  
Phytophthora Cinnamomi ◽  
Chemical Stimulation ◽  
Mating Types ◽  
Hyphal Fusion ◽  
Field Isolates ◽  
Heterokaryon Formation ◽  
Oospore Formation

The mating type behaviour of 176 single zoospore isolates collected from 11 dissected sporangia of Phytophthora cinnamomi Rands was examined and the results confirmed previous conclusions from studies of field isolates, that two compatibility types may be involved in the formation of oospores in this fungus. The bilateral formation of sexual spores in paired cultures is believed to occur via the hyphal fusion of two compatibility types and it is thought that chemical stimulation is not involved. Oospore production is also affected by nutrition and innate characters of the isolates used. Determination of the mating reactions of terminal hyphae isolated from mixed A1 and A2 cultures suggested that extensive heterokaryosis of A1 and A2 type nuclei did not occur in the vegetative hyphae of either mating type, and that heterokaryon formation was probably restricted to the site of oospore formation. The absence of 'vegetative' heterokaryosis between the two mating types of P. cinnamomi is postulated and the control of sexuality in this fungus is discussed.

scholarly journals GENETICS OF CHEMICAL INDUCTION OF CONJUGATION IN PARAMECIUM AURELIA

Genetics ◽  
1974 ◽  
Vol 76 (4) ◽  
pp. 703-714
Author(s):  
Donald L Cronkite
Keyword(s):  
Mating Type ◽  
Recessive Gene ◽  
Mating Types ◽  
Wild Type ◽  
Chemical Induction ◽  
Single Mating ◽  
In Cells

ABSTRACT Certain stocks of P. aurelia, syngen 8, could not be induced to conjugate in a solution (KCl + acriflavine + calcium-poor conditions) which was effective in inducing conjugation in other species of Paramecium as well as in other stocks of syngen 8. Both stocks could conjugate by interaction with cells of complementary mating type. Breeding analysis shows that each of the two stocks is homozygous for a recessive gene that blocks induction of conjugation by the KCl-acriflavine solution. These two genes are neither allelic nor linked. Analyses of the phenotypes of the two uninducibles and the wild type were carried out by attempting to induce mating in cells of a single mating type by exposing them to detached mating-reactive cilia from cells of complementary mating type and to the KCl-acriflavine solution, either sequentially or simultaneously. The results confirm the conclusions of others that there is at least one unique step in chemical induction not shared with induction by interaction of complementary mating types. But the results also indicate that there is more than one unique step in chemical induction and that the effects of the two genes described here operate during different periods of the hour required for chemical induction.

scholarly journals Mating-Type Locus Organization and Mating-Type Chromosome Differentiation in the Bipolar Edible Button Mushroom Agaricus bisporus

Genes ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 1079
Author(s):  
Marie Foulongne-Oriol ◽  
Ozgur Taskent ◽  
Ursula Kües ◽  
Anton S. M. Sonnenberg ◽  
Arend F. van Peer ◽  
...  
Keyword(s):  
Mating Type ◽  
Agaricus Bisporus ◽  
Reference Genome ◽  
Mating Types ◽  
Button Mushroom ◽  
Recombination Suppression ◽  
Type Locus ◽  
Mating Type Locus ◽  
Sexual Compatibility ◽  
Single Mating

In heterothallic basidiomycete fungi, sexual compatibility is restricted by mating types, typically controlled by two loci: PR, encoding pheromone precursors and pheromone receptors, and HD, encoding two types of homeodomain transcription factors. We analysed the single mating-type locus of the commercial button mushroom variety, Agaricus bisporus var. bisporus, and of the related variety burnettii. We identified the location of the mating-type locus using genetic map and genome information, corresponding to the HD locus, the PR locus having lost its mating-type role. We found the mip1 and β-fg genes flanking the HD genes as in several Agaricomycetes, two copies of the β-fg gene, an additional HD2 copy in the reference genome of A. bisporus var. bisporus and an additional HD1 copy in the reference genome of A. bisporus var. burnettii. We detected a 140 kb-long inversion between mating types in an A. bisporus var. burnettii heterokaryon, trapping the HD genes, the mip1 gene and fragments of additional genes. The two varieties had islands of transposable elements at the mating-type locus, spanning 35 kb in the A. bisporus var. burnettii reference genome. Linkage analyses showed a region with low recombination in the mating-type locus region in the A. bisporus var. burnettii variety. We found high differentiation between β-fg alleles in both varieties, indicating an ancient event of recombination suppression, followed more recently by a suppression of recombination at the mip1 gene through the inversion in A. bisporus var. burnettii and a suppression of recombination across whole chromosomes in A. bisporus var. bisporus, constituting stepwise recombination suppression as in many other mating-type chromosomes and sex chromosomes.

scholarly journals Dynamics of the sex ratio in Tetrahymena thermophila

2018 ◽  
Author(s):  
Guangying Wang ◽  
Kai Chen ◽  
Jing Zhang ◽  
Xuefeng Ma ◽  
Shanjun Deng ◽  
...  
Keyword(s):  
Population Genetics ◽  
Sex Ratio ◽  
Mating Systems ◽  
Tetrahymena Thermophila ◽  
Mating Types ◽  
Eukaryotic Lineage ◽  
Single Sex ◽  
Theoretical Predictions ◽  
The Impact ◽  
Insight Into

AbstractSex is often hailed as one of the major successes in evolution, and in sexual organisms the maintenance of proper sex ratio is crucial. As a large unicellular eukaryotic lineage, ciliates exhibit tremendous variation in mating systems, especially the number of sexes and the mechanism of sex determination (SD), and yet how the populations maintain proper sex ratio is poorly understood. Here Tetrahymena thermophila, a ciliate with seven mating types (sexes) and probabilistic SD mechanism, is analyzed from the standpoint of population genetics. It is found based on a newly developed population genetics model that there are plenty of opportunities for both the co-existence of all seven sexes and the fixation of a single sex, pending on several factors, including the strength of natural selection. To test the validity of predictions, five experimental populations of T. thermophila were maintained in the laboratory so that the factors that can influence the dynamics of sex ratio could be controlled and measured. Furthermore, whole-genome sequencing was employed to examine the impact of newly arisen mutations. Overall, it is found that the experimental observations highly support theoretical predictions. It is expected that the newly established theoretical framework is applicable in principle to other multi-sex organisms to bring more insight into the understanding of the maintenance of multiple sexes in a natural population.

scholarly journals Differential Gene Expression between Fungal Mating Types Is Associated with Sequence Degeneration

2020 ◽  
Vol 12 (4) ◽  
pp. 243-258 ◽  
Author(s):  
Wen-Juan Ma ◽  
Fantin Carpentier ◽  
Tatiana Giraud ◽  
Michael E Hood
Keyword(s):  
Differential Expression ◽  
Differentially Expressed Genes ◽  
Mating Type ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Gc Content ◽  
Differentially Expressed ◽  
Mating Types ◽  
Sexual Antagonism ◽  
Recombination Suppression

Abstract Degenerative mutations in non-recombining regions, such as in sex chromosomes, may lead to differential expression between alleles if mutations occur stochastically in one or the other allele. Reduced allelic expression due to degeneration has indeed been suggested to occur in various sex-chromosome systems. However, whether an association occurs between specific signatures of degeneration and differential expression between alleles has not been extensively tested, and sexual antagonism can also cause differential expression on sex chromosomes. The anther-smut fungus Microbotryum lychnidis-dioicae is ideal for testing associations between specific degenerative signatures and differential expression because 1) there are multiple evolutionary strata on the mating-type chromosomes, reflecting successive recombination suppression linked to mating-type loci; 2) separate haploid cultures of opposite mating types help identify differential expression between alleles; and 3) there is no sexual antagonism as a confounding factor accounting for differential expression. We found that differentially expressed genes were enriched in the four oldest evolutionary strata compared with other genomic compartments, and that, within compartments, several signatures of sequence degeneration were greater for differentially expressed than non-differentially expressed genes. Two particular degenerative signatures were significantly associated with lower expression levels within differentially expressed allele pairs: upstream insertion of transposable elements and mutations truncating the protein length. Other degenerative mutations associated with differential expression included nonsynonymous substitutions and altered intron or GC content. The association between differential expression and allele degeneration is relevant for a broad range of taxa where mating compatibility or sex is determined by genes located in large regions where recombination is suppressed.

scholarly journals Molecular Epidemiology and Whole-Genome Analysis of Bovine Foamy Virus in Japan

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1017
Author(s):  
Hirohisa Mekata ◽  
Tomohiro Okagawa ◽  
Satoru Konnai ◽  
Takayuki Miyazawa
Keyword(s):  
Phylogenetic Analyses ◽  
Foamy Virus ◽  
Pcr Analysis ◽  
Whole Genome ◽  
Genome Sequences ◽  
Whole Genome Analysis ◽  
Virus Family ◽  
Bovine Foamy Virus ◽  
Novel Genotype

Bovine foamy virus (BFV) is a member of the foamy virus family in cattle. Information on the epidemiology, transmission routes, and whole-genome sequences of BFV is still limited. To understand the characteristics of BFV, this study included a molecular survey in Japan and the determination of the whole-genome sequences of 30 BFV isolates. A total of 30 (3.4%, 30/884) cattle were infected with BFV according to PCR analysis. Cattle less than 48 months old were scarcely infected with this virus, and older animals had a significantly higher rate of infection. To reveal the possibility of vertical transmission, we additionally surveyed 77 pairs of dams and 3-month-old calves in a farm already confirmed to have BFV. We confirmed that one of the calves born from a dam with BFV was infected. Phylogenetic analyses revealed that a novel genotype was spread in Japan. In conclusion, the prevalence of BFV in Japan is relatively low and three genotypes, including a novel genotype, are spread in Japan.

scholarly journals Constraints on neutrino non-standard interactions from LHC data with large missing transverse momentum

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
DianYu Liu ◽  
ChuanLe Sun ◽  
Jun Gao
Keyword(s):  
Transverse Momentum ◽  
Neutral Current ◽  
Data Sets ◽  
Leading Order ◽  
Missing Transverse Momentum ◽  
Upper Limit ◽  
Theoretical Predictions ◽  
Parton Showering ◽  
Single Jet

Abstract The possible non-standard interactions (NSIs) of neutrinos with matter plays important role in the global determination of neutrino properties. In our study we select various data sets from LHC measurements at 13 TeV with integrated luminosities of 35 ∼ 139 fb−1, including production of a single jet, photon, W/Z boson, or charged lepton accompanied with large missing transverse momentum. We derive constraints on neutral-current NSIs with quarks imposed by different data sets in a framework of either effective operators or simplified Z′ models. We use theoretical predictions of productions induced by NSIs at next-to-leading order in QCD matched with parton showering which stabilize the theory predictions and result in more robust constraints. In a simplified Z′ model we obtain a 95% CLs upper limit on the conventional NSI strength ϵ of 0.042 and 0.0028 for a Z′ mass of 0.2 and 2 TeV respectively. We also discuss possible improvements from future runs of LHC with higher luminosities.

scholarly journals Deletion of the Schizophyllum commune Aα Locus: The Roles of Aα Y and Z Mating-Type Genes

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1437-1444
Author(s):  
C Ian Robertson ◽  
Kirk A Bartholomew ◽  
Charles P Novotny ◽  
Robert C Ullrich
Keyword(s):  
Mating Type ◽  
Sexual Development ◽  
Schizophyllum Commune ◽  
Mating Types ◽  
Developmental Pathway ◽  
Mating Type Gene ◽  
Mating Type Genes ◽  
Regulatory Loci ◽  
Type Gene

The Aα locus is one of four master regulatory loci that determine mating type and regulate sexual development in Schizophyllum commune. We have made a plasmid containing a URA1 gene disruption of the Aα Y1 gene. Y1 is the sole Aα gene in Aα1 strains. We used the plasmid construction to produce an Aα null (i.e., AαΔ) strain by replacing the genomic Y1 gene with URA1 in an Aα1 strain. To characterize the role of the Aα genes in the regulation of sexual development, we transformed various Aα Y and Z alleles into AαΔ strains and examined the acquired mating types and mating abilities of the transformants. These experiments demonstrate that the Aα Y gene is not essential for fungal viability and growth, that a solitary Z Aα mating-type gene does not itself activate development, that Aβ proteins are sufficient to activate the A developmental pathway in the absence of Aα proteins and confirm that Y and Z genes are the sole determinants of Aα mating type. The data from these experiments support and refine our model of the regulation of A-pathway events by Y and Z proteins.

scholarly journals Determination of the Height of Hard X-Ray Sources in the Solar Atmosphere by Measurement of Photospheric Albedo Photons

1975 ◽  
Vol 68 ◽  
pp. 239-241
Author(s):  
John C. Brown ◽  
H. F. Van Beek
Keyword(s):  
Solar Atmosphere ◽  
The Other ◽  
X Ray ◽  
Theoretical Predictions ◽  
Source Models ◽  
The One

SummaryThe importance and difficulties of determining the height of hard X-ray sources in the solar atmosphere, in order to distinguish source models, have been discussed by Brown and McClymont (1974) and also in this Symposium (Brown, 1975; Datlowe, 1975). Theoretical predictions of this height, h, range between and 105 km above the photosphere for different models (Brown and McClymont, 1974; McClymont and Brown, 1974). Equally diverse values have been inferred from observations of synchronous chromospheric EUV bursts (Kane and Donnelly, 1971) on the one hand and from apparently behind-the-limb events (e.g. Datlowe, 1975) on the other.

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