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65 results for “Tetrahymena thermophila”
Evolution under pH stress and high population densities leads to increased density-dependent fitness in the protist Tetrahymena thermophila
<p>Abiotic stress is a major force of selection that organisms are constantly facing. While the evolutionary effects of various stressors have been broadly studied, it is only more recently that the relevance of interactions between evolution and underlying ecological conditions, that is, eco-evolutionary feedbacks, have been highlighted. Here, we experimentally investigated how populations adapt to pH-stress under high population densities. Using the protist species <em>Tetrahymena thermophila</em>, we studied how four different genotypes evolved in response to stressfully low pH conditions and high population densities. We found that genotypes underwent evolutionary changes, some shifting up and others shifting down their intrinsic rates of increase (<em>r<sub>0</sub></em>). Overall, evolution at low pH led to the convergence of <em>r<sub>0</sub></em> and intraspecific competitive ability (<em>α</em>) across the four genotypes. Given the strong correlation between <em>r<sub>0</sub></em> and <em>α</em>, we argue that this convergence was a consequence of selection for increased density-dependent fitness at low pH under the experienced high density conditions. Increased density-dependent fitness was either attained through increase in <em>r<sub>0</sub></em> , or decrease of <em>α</em>, depending on the genetic background. In conclusion, we show that demography can influence the direction of evolution under abiotic stress.</p> <p> </p>
Fig. 9. T. thermophila cells immunostained with monoclonal anti-cdc14A in Effects of Roscovitine on Schedule of Divisional Morphogenesis, Basal Bodies Proliferation and Cell Divisions in Tetrahymena thermophila
Fig. 9. T. thermophila cells immunostained with monoclonal anti-cdc14A antibody. Cs and nCS – apical couplets of basal bodies for proter and opisthe, respectively; Ma – macronucleus. Other explanations as in Figs 1 and 8. Bar: 10 µm, bar in D for B–D.
Fig. 7. T. thermophila cells immunostained with the antiserum against component B in Effects of Roscovitine on Schedule of Divisional Morphogenesis, Basal Bodies Proliferation and Cell Divisions in Tetrahymena thermophila
Fig. 7. T. thermophila cells immunostained with the antiserum against component B of epiplasm. DF – staining around the deep fibers. Other explanations as in Fig. 1. Bar: 10 µm.
Fig. 2 in Effects of Roscovitine on Schedule of Divisional Morphogenesis, Basal Bodies Proliferation and Cell Divisions in Tetrahymena thermophila
Fig. 2. Localization of nuclei in control and roscovitine treated T. tetrmophila. The cells were immunostained with the anti-centrin 20H5 antibody and stained with DAPI. A and B – control cells in the VI stage of morphogenesis, and early cytokinesis, respectively; C and D – roscovitine treated cells (4 h) in the VI stage of morphogenesis and in cytokinesis respectively. Arrows – micronuclei (in the C micronucleus in opisthe is out of focus). Bar: 10 µm.
Fig. 4. Postdivider cells after 5.5 h in Effects of Roscovitine on Schedule of Divisional Morphogenesis, Basal Bodies Proliferation and Cell Divisions in Tetrahymena thermophila
Fig. 4. Postdivider cells after 5.5 h of roscovitine treatment. Cells were immunostained with anti-centrin 20H5 antibody. A and A' – ventral and dorsal views of the same proter cell with remnants of the OA2; B–C opisthe cells, B – opisthe with ARF on dorsal side, C – opisthe with remnants of oral structures; D and D' – ventral and dorsal views of the same cell; E and E' – ventral and dorsal views of the same opisthe during pinching off the OA. Other explanations as in Fig. 1. Bar: 10 µm for A–E'.
Fig. 5 in Effects of Roscovitine on Schedule of Divisional Morphogenesis, Basal Bodies Proliferation and Cell Divisions in Tetrahymena thermophila
Fig. 5. Mean cell sizes, positions of OA1, OA2 and fission zone in control and in roscovitine treated cells. Upper panel: early and late control dividers, lower panel: early dividers after 3.5 h roscovitine treatment, late dividers after 3.5 and 5.5 h roscovitine treatment. The shape of cells is represented by elipses. Solid horizontal lines – cells "equator", dotted horizontal lines – positions of the fission furrow. All sizes and distances were drawn to the same scale. Bar: 10 µm. The measurements represent means of at least 10 specimens for each cell sample.
Fig. 6 in Effects of Roscovitine on Schedule of Divisional Morphogenesis, Basal Bodies Proliferation and Cell Divisions in Tetrahymena thermophila
Fig. 6. Correlation of length of proters and shift of the fission zone in relation to OA2 induced by roscovitine in late dividers. The shift of the fission zone was measured as a difference between length of the proters and distance from cell apex to the anterior end of the OA2 (ordinate). Each point in this diagram represent individual cell. Open symbols – untreated cells, close symbols – cells treated with roscovitine for 3.5 and 5.5 h (pooled).
Fig. 10 in Effects of Roscovitine on Schedule of Divisional Morphogenesis, Basal Bodies Proliferation and Cell Divisions in Tetrahymena thermophila
Fig. 10. Western blot of T. thermophila fractions with monoclonal antibody anti-cdc14A. H – homogenate, S – supernatant, C – cortical fraction (pellet).
Data from: Selection on growth rate and local adaptation drive genomic adaptation during experimental range expansions in the protist Tetrahymena thermophila
<p>1. Populations that expand their range can undergo rapid evolutionary adaptation of life-history traits, dispersal behaviour, and adaptation to the local environment. Such adaptation may be aided or hindered by sexual reproduction, depending on the context.</p> <p>2. However, few empirical and experimental studies have investigated the genetic basis of adaptive evolution during range expansions. Even less attention has been given to the question how sexual reproduction may modulate such adaptive evolution during range expansions.</p> <p>3. We here studied genomic adaptation during experimental range expansions of the protist <em>Tetrahymena thermophila</em>in landscapes with a uniform environment or a pH-gradient. Specifically, we investigated two aspects of genomic adaptation during range expansion. Firstly, we investigated adaptive genetic change in terms of the underlying numbers of allele frequency changes from standing genetic variation and <em>de novo</em><span> variants. We focused on how sexual reproduction may alter this adaptive genetic change. Secondly, we identified genes subject to selection caused by the expanding range itself, and directional selection due to the presence or absence of the pH-gradient. We focused this analysis on alleles with large frequency changes that occurred in parallel in more than one population to identify the most likely candidate targets of selection. </span></p> <p><span>4. We found that sexual reproduction altered adaptive genetic change both in terms of <em>de novo</em></span><span> variants and standing genetic variation. However, sexual reproduction affected allele frequency changes in standing genetic variation only in the absence of long-distance gene flow. Adaptation to the range expansion affected genes involved in cell divisions and DNA repair, whereas adaptation to the pH-gradient additionally affected genes involved in ion balance, and oxidoreductase reactions. These genetic changes may result from selection on growth and adaptation to low pH. </span></p> <p><span>5. In the absence of gene flow, sexual reproduction may have aided genetic adaptation. Gene flow may have swamped expanding populations with maladapted alleles, thus reducing the extent of evolutionary adaptation during range expansion. Sexual reproduction also altered the genetic basis of adaptation in our evolving populations via <em>de novo </em>variants, possibly by purging deleterious mutations or by revealing fitness benefits of rare genetic variants. </span></p>
Evolution under pH stress and high population densities leads to increased density-dependent fitness in the protist Tetrahymena thermophila
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Data from: Selection on growth rate and local adaptation drive genomic adaptation during experimental range expansions in the protist Tetrahymena thermophila
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The phenotypic and fitness response to the combination of copper and thermal stressors strongly varies within the ciliate species, Tetrahymena thermophila
<p><span>Copper pollution can alter biological and trophic functions. Organisms can set up different tolerance strategies, including accumulation mechanisms (intracellular vacuoles, external chelation, etc.) to maintain themselves in copper-polluted environments. Accumulation mechanisms can influence the expression of other phenotypic traits, allowing organisms to improve their fitness. Whether copper effects on accumulation strategies interact with other environmental stressors such as temperature and how this may differ within species are still unsolved questions. Here, we tested experimentally whether the combined effect of copper and temperature modulates traits linked to fitness, morphology, movement and accumulation in six strains of the ciliate <em>Tetrahymena</em> <em>thermophila</em>. We also explored whether copper accumulation might modulate environmental copper concentration effects on phenotypic and fitness traits. Results showed high intraspecific variability in the phenotypic and fitness response to copper, with interactive effects between temperature and copper. In addition, they suggested an attenuation effect of copper accumulation on the sensitivity of traits to copper, but with great variation between strains, temperature and copper concentration. Diversity of responses among strains and their thermal dependencies pleads for the integration of intraspecific variability and multiple stressors approaches in ecotoxicological studies, thus improving the reliability of assessments of the effects of pollutants on biodiversity.</span></p>
Mass spectrometry of axonemes from Tetrahymena thermophila CU428 and acetylation mutants
<p>Acetylation of α-tubulin at the lysine 40 residue (αK40) by the ATAT1/MEC-17 acetyltransferase influences the properties of microtubules and is a widespread phenomenon in eukaryotic cells. Previous research indicates that microtubules that undergo acetylation at αK40 are more stable and resilient to damage. Notably, αK40 acetylation represents the sole identified post-translational modification site within the microtubule lumen, suggesting its role in regulating the lateral interactions among protofilaments within the microtubule structure. This investigation focuses on evaluating the impact of tubulin acetylation on doublet microtubules present in the cilia of <em>Tetrahymena thermophila</em>, employing mass spectrometry analysis. Cilia samples derived from <em>Tetrahymena</em> wild type, acetylation mutants (K40R and MEC17-Knockout), and non-acetylation mutants (RIB72B-Knockout and RIB72AB-Knockout) underwent comparative mass spectrometry analysis. The results from mass spectrometry revealed a correlation between αK40 acetylation and phosphorylation within the ciliary structures.</p>
MAC genome assembly and gene prediction of Tetrahymena thermophila SB210
<p>Corrected genome assembly and gene prediction of the MAC genome of T. thermophila SB210. These data were generated and analysed in the manuscript "Single-nucleotide polymorphism landscape of the macronuclear genome of <em>Tetrahymena thermophila".</em></p> <p>Please see the Material & methods and Supplementary data files of this manuscript for more details about these files.</p>
Mass spectrometry of axonemes from Tetrahymena thermophila CU428 and acetylation mutants
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The phenotypic and fitness response to the combination of copper and thermal stressors strongly varies within the ciliate species, Tetrahymena thermophila
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Data from: Phenotypic responses to temperature in the ciliate Tetrahymena thermophila
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Data from: Gene swamping alters evolution during range expansions in the protist Tetrahymena thermophila
<p>At species' range edges, individuals often face novel environmental conditions that may limit range expansion until populations adapt. The potential to adapt depends on genetic variation upon which selection can act. However, populations at species' range edges are often genetically depauperated. One mechanism to increase genetic variation is to reshuffle existing variation through sex. During range expansions, sex can, however, act as a double-edged sword. The gene swamping hypothesis predicts that for populations expanding along an abiotic gradient, sex can hinder adaptation if asymmetric dispersal leads to numerous maladapted dispersers from the range core swamping the range edge. In this study, we experimentally tested the gene swamping hypothesis by performing replicated range expansions in landscapes with or without an abiotic pH-gradient, using the ciliate <i>Tetrahymena thermophila</i>, while simultaneously manipulating the occurrence of gene flow and sex. We show that sex accelerated evolution of local adaptation in the absence of gene flow, but hindered it in the presence of gene flow. The effect of sex, however, was independent of the pH-gradient, indicating that not only abiotic gradients but also the biotic gradient in population density leads to gene swamping. Overall, our results show that gene swamping can affect adaptation in life-history strategies.</p>
Data from: Genetic background alters dominance relationships between mat alleles in the ciliate Tetrahymena thermophila
The pattern of inheritance and mechanism of sex determination can have important evolutionary consequences. We studied probabilistic sex determination in the ciliate Tetrahymena thermophila, which was previously shown to cause evolution of skewed sex ratios. We find that the genetic background alters the sex determination patterns of mat alleles in heterozygotes and that allelic interaction can differentially influence the expression probability of the 7 sexes. We quantify the dominance relationships between several mat alleles and find that A-type alleles, which specify sex I, are indeed recessive to B-type alleles, which are unable to specify that sex. Our results provide additional support for the presence of modifier loci and raise implications for the dynamics of sex ratios in populations of T. thermophila.
Mass spectrometry of natively decorated doublet microtubule from Tetrahymena thermophila WT and mutants
<p>Cilia are thin microtubule-based protrusions of eukaryotic cells. The swimming of ciliated protists and sperm cells is propelled by the beating of cilia. Cilia propagate the flow of mucus in the trachea and protect the human body from viral infections. The main force generators of ciliary beating are the outer dynein arms (ODAs) which attach to the doublet microtubules. The bending of cilia is driven by the ODAs' conformational changes caused by ATP hydrolysis. Here, we report the native ODA complex structure attaching to the doublet microtubule by cryo-electron microscopy and mass spectrometry. The structure reveals how the ODA complex is attached to the doublet microtubule via the docking complex in its native state. Combined with coarse-grained molecular dynamics simulations, we present a model of how the attachment of the ODA to the doublet microtubule induces remodeling and activation of the ODA complex.</p>
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