To see the other types of publications on this topic, follow the link: Tetraploid.
Dissertations / Theses on the topic 'Tetraploid'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Tetraploid.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Crockford, Andrew. "Deciphering tetraploid tolerance." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1475158/.
Full textAbstract:
Chromosomal instability and aneuploidy are common features of human malignancies, which fuel genetic heterogeneity and can lead to inaccurate diagnosis and treatment failure. Tetraploidy has been shown as an intermediate of aneuploidy and, thus, understanding the molecular mechanisms governing tetraploid tolerance is of great importance. A frequent tolerance mechanism observed in experimental systems and human tumours is loss of TP53, highlighting its central role in the tetraploidy checkpoint. However, despite this association, more than half of genome-doubled tumours are TP53 wild-type. The aim of this project was to understand how tetraploid cells could tolerate the polyploidy phenotype with a functional p53/p21 axis. Firstly, tetraploidy tolerance was investigated in an isogenic HCT-116 diploid and tetraploid system. The HCT-116 tetraploids showed functional p53, in response to DNA damage and segregation error induction, while also displayed elevated basal level of both proteins. Despite this, the tetraploid clones could proliferate and showed no evidence of cell cycle arrest, suggesting the p53/p21 tetraploidy checkpoint response had been overridden. Quantitative proteomics revealed cyclin D1 overexpression in the tetraploid clones. As cyclin D1 can sequester p21, their relationship was investigated and validated in the HCT-116 system. To further test if elevated cyclin D1 could affect tolerance, cytokinesis failure was pharmacologically induced in RPE cells, where cyclin D1 overexpression promoted tetraploidy tolerance across multiple assays. In addition, bioinformatics analysis revealed that D-type cyclins were overexpressed in TP53, CDKN1A and RB1 wild-type, genome-doubled testicular germ cell tumours (TGCT). These findings indicate that D-type cyclin overexpression can provide tetraploidy tolerance in vitro and may be implicated in TGCT genome-doubling and pathogenesis.
2
Muramoto, H. "Tetraploid Caducous Bract Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/203924.
Full text
3
Tavakkol, Afshari Reza. "Variation in seed dormancy of tetraploid wheat." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ37916.pdf.
Full text
4
Kuffer, Christian. "Proliferation and arrest of human tetraploid cells." Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-182558.
Full textAbstract:
Durch Fehler entstandene tetraploide Zellen sind chromosomal instabil und können zu Zelltransformation führen. Die Beweise verdichten sich, dass die Propagation von tetraploiden Säugetierzellen durch einen p53-vermittelten Arrest eingeschränkt wird; jedoch ist weiterhin unklar, was die Ursache dieses p53-vermittelten Arrests ist.
Um die Ursache des p53-vermittelten Arrests zu identifizieren, wurden individuelle Zellen mittels zeitraffender Mikroskopie in Echtzeit verfolgt. Neu entstandene tetraploide Zellen können einen Zellzyklus vollenden, aber die Mehrzahl der Zellen starb oder verharrte in einem Arrest in der folgenden G1-Phase, abhängig davon ob die vorangegangene Mitose fehlerfrei verlief oder nicht. Tochterzellen, denen eine fehlerhafte Mitose voranging, akkumulierten p53 im Zellkern, was zum Zelltod oder einem irreversiblen Zellzyklusarrest führte. Es zeigte sich durch den Anstieg von 8-OHdG, einem Indikator für oxidative DNA Schädigung, dass tetraploide Zellen durch die vermehrten fehlerhaften Mitosen höheren Konzentrationen von reaktiven oxidativen Spezien (ROS) ausgesetzt sind. Der Anstieg von 8-OHdG korrelierte mit der p53-Akkumulation im Zellkern. Da keine vermehrte Phosphorylierung des Histons H2AX (γ-H2AX), ein Marker für DNA-Strangbrüche, detektiert wurde, lässt sich schlussfolgern, dass ROS entscheidend für den p53 vermittelten Arrest verantwortlich sind.
Mehrere p53-aktivierende Kinasen wurden mittels RNA Interferenz (RNAi) und chemischer Genetik untersucht, ob sie einen Einfluss auf den Zellzyklusarrest von tetraploiden Zellen haben. Von den getesteten Kinasen hatte nur ATM einen Einfluss auf die Aktivierung von p53 nach fehlerhaften tetraploiden Mitosen. Zwar wird ATM in der Regel durch DNA-Schäden aktiviert, jedoch wurde bereits zuvor gezeigt, dass ATM auch durch erhöhte ROS Konzentrationen aktiviert werden kann.
Um die Zusammenhänge des Zellzyklusarrests weiter aufzuklären, wurde ein genomübergreifender esiRNA Screen etabliert, der die Zellproliferation nach induzierter Tetraploidisierung analysiert. Durch Kombination der Zellzyklusanalyse an Hand des DNA-Gehalts zusammen mit den FUCCI-Zellzyklusindikatoren, konnten tetraploide und diploide Zellen nebeneinander mikroskopisch analysiert werden, ohne zuvor tetraploide und diploide Zellen isolieren zu müssen. Dieser neue experimentelle Ansatz ermöglichte die Identifikation von Genen, die spezifisch die Proliferation von tetraploiden Zellen verstärken oder einschränken
Im Primärscreen wurden 1159 Gene identifiziert, deren Inhibition die Proliferation einschränken. Weiter wurden 431 Gene identifiziert, deren Inhibition die Proliferation der tetraploiden Zellen verstärken. Von den 431 Genen, deren Inhibition die Proliferation verstärken, wurden 371 Gene einem Konfirmationsscreen unterzogen, in dem 158 der identifizierten 371 Gene bestätigt wurden. Die bioinformatische Analyse der 158 Gene zeigte eine signifikante Anhäufung von Genen, die mit DNA-Replikation, dem kanonischen Wnt-Signalweg oder mit Tumorsignalwegen assoziiert sind. Unter letzteren ist CCDC6 sehr interessant, da dessen Genprodukt durch ATM phosphoryliert wird und nachgeschaltet den Tumorsuppressor 14-3-3σ reguliert.
Des weiteren wurden mittels einer Meta Analyse der Ergebnisse des Primärscreens, zusammen mit den Daten aus dem “Project Achilles”, welches genomweit den Effekt von shRNA-vermittelter Geninhibition auf die Proliferation von 108 Krebszelllinien untersuchte, 18 Gene identifiziert, deren Inhibition sowohl die Proliferation von tetraploiden Zellen einschränkt, als auch die Proliferation von Zelllinien hemmt, welche von Krebsarten stammen, die zu meist chromosomale Instabilitäten (CIN) aufweisen.
Damit bilden die präsentierten Daten nicht nur eine gute Basis zur Aufklärung des Zellzyklusarrests tetraploider Zellen, sondern auch für die Identifikation neuer potentieller Zielmoleküle, welche benutzt werden können um Tumorerkrankungen mit chromosomaler Instabilität zu behandeln, welche häufig resistent gegen die bislang verfügbaren Behandlungen sind.<br>Erroneously arising tetraploid mammalian cells are chromosomally unstable and may facilitate cell transformation. An increasing body of evidence suggests that the propagation of mammalian tetraploid cells is limited by a p53-dependent arrest, however, the triggers of this arrest have thus far not been identified.
To elucidate the timing and causes of this arrest, time-lapse live cell imaging was performed to track the fate of individual cells immediately after tetraploidization. Newly formed tetraploid cells can progress through one cell cycle, but the majority of cells arrest or die in the subsequent G1 stage, with the fate of these tetraploid cells determined by the preceding mitosis. Daughter cells arising from defective mitosis accumulated p53 in the nucleus, which led to irreversible cell cycle arrest or death. Furthermore this p53 accumulation coincides and correlates with an increase of the oxidative DNA damage marker 8-OHdG, suggesting an increase in reactive oxygen species (ROS), but does not coincide with the phosphorylation of H2AX (γ-H2AX), a marker for canonical DNA damage.
Using RNA interference and chemical genetics, several p53 activating kinases were tested for their contribution to the cell cycle arrest of tetraploid cells. Of the tested kinases, only ATM was shown to play a role in the activation of p53 after defects in mitosis. ATM kinase is a DNA damage-responsive kinase, however, it has been shown that increased ROS levels activate ATM in a non-canonical way.
To gain further insights into arrest of tetraploid cells, an unbiased genome-wide esiRNA screen was performed to analyze cell proliferation after induced tetraploidization. Using FUCCI cell cycle probes, combined with DNA content cell cycle profiling, allowed an image-based assay to examine tetraploid and diploid cells side-by-side. This novel approach enabled us to screen for genes that specifically restricts or enhances cell proliferation after tetraploidization, if inhibited by esiRNA mediated knockdown.
From the primary screen we identified 1159 genes that decreased and 431 genes that increased the cell proliferation after tetraploidization, if knocked down by esiRNA. From the 431 genes that increased proliferation upon knockdown, 374 were selected and subjected to a re-screen. Of these 374 genes, we were able to confirm the results for 158 of the genes. A bioinformatics analysis of the 158 genes for which the phenotype were confirmed by the re-screen revealed a significant enrichment of genes involved in DNA replication, the canonical Wnt signaling pathway and in pathways linked to cancer. Among the latter, CCDC6 is particularly interesting, because its gene product is a target of the ATM kinase and an upstream regulator of the tumor suppressor 14-3-3σ.
Moreover, by comparing the results of the primary screen with the data of the “Project Archilles”, which measured the proliferation in genome wide pooled-shRNA screens for 108 cancer cell lines, 18 genes were identified that are essential for the proliferation of cells after tetraploidization, as well as for the proliferation of cancer cell lines that derive from cancer types with a high incidence for chromosomal instability (CIN).
Taken together, the presented data builds an excellent resource not only for elucidating how the arrest after tetraploidization is mediated, but also to identify novel potential therapeutic targets against tumors with CIN, which are frequently resistant to many of today’s anti-cancer therapies.
5
Khan, Javed Ahmad. "Salinity effects on 4D recombinant tetraploid wheat genotypes." Thesis, Bangor University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321525.
Full text
6
Diffoot, Nanette. "Corydoras aeneus: a diploid-tetraploid fish species complex." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/101468.
Full textAbstract:
Corydoras aeneus is an armoured catfish found in the upper amazon regions of South America. It is a member of the family Callichthyidae. Studies done with this species of fish showed that C. aeneus is a tetraploid with a chromosome number of 132 (Scheel et al. , 1972). Dunham et al. (1980) reported 120 chromosomes. The C. aeneus used in this study were bought from direct importers. We had four samples of fishes supposedly coming from Brazil (Belem), Guyana, Peru and Trinidad. During our initial studies in an attempt to karyotype aeneus we came across individuals with a highly reduced chromosome number. A diploid form of C. aeneus was discovered. Only those fishes from our Belem sample were diploid. A comparison of the diploid and tetraploid forms was done. Both forms were karyotyped, the tetraploid form of C. aeneus has 134 chromosomes and the diploid has 56. Physically both forms looked exactly the same. Morphometric as well as meristic data was collected from 131 fishes and analyzed by multivariate, discriminant and contingency chi- square analyses. The results obtained do not suggest any absolute morphological differences between the diploid and the tetraploid forms anymore than between tetraploids.<br>M.S.
7
Morgan, Christopher Henry. "Coordination of meiotic recombination in diploid and tetraploid arabidopsis." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/7092/.
Full textAbstract:
Homologous recombination is an integral part of meiosis and is essential for generating crossovers that ensure balanced segregation of homologous chromosomes and establish genetic variation within offspring. It is therefore exceedingly important that meiotic cells employ stringent control mechanisms to safeguard crossover formation. Work in yeast has indicated that the meiotic axis, a proteinaceous structure that tethers meiotic chromosomes into looped arrays, plays a crucial role in many aspects of homologous recombination, from double strand break formation to crossover interference. It has also been suggested that increased crossover interference helps to establish meiotic stability by inhibiting multivalent formation during autopolyploid meiosis. Using immunocytochemistry coupled with super-resolution microscopy, we have further investigated the role played by the meiotic axis protein ASY1 in stabilising meiosis in the established autotetraploid Arabidopsis arenosa. We have also used Arabidopsis arenosa as a model for studying how meiotic interference might operate within an autopolyploid context. Alongside this, experiments using transgenic lines of the model plant Arabidopsis thaliana have helped to shed light on how crossover formation and synapsis are affected by reduced expression of ASY1 and ASY3 and to determine what effect limiting meiotic crossover numbers might have on neopolyploid meiotic stabilisation.
8
Schuck, Susan M., and Steven P. McLaughlin. "Flowering Phenology and Outcrossing in Tetraploid Grindelia camporum Green." University of Arizona (Tucson, AZ), 1988. http://hdl.handle.net/10150/609102.
Full textAbstract:
Several reproductive processes of tetraploid Grindelia camporum were investigated. This plant is a potential resin crop for the southwestern United States. Field observations of 100 flower heads from unopened buds through 100% achene dispersal were made. It was found that individual flower heads are available for pollination for approximately 5 days but all disc florets are open for only 1 day. On average, achenes mature in 22 days and are dispersed 53 days after flowering. Fourteen-hundred hand-pollinations were also made on plants from 6 wild populations of G. camporum grown in a greenhouse and shade house. Estimates of fertility and crossability of populations were made based on achene number and achene weight data from these crosses. All populations studied were interfertile and no evidence of outbreeding depression in between -population crosses was found. It is shown that tetraploid G. camporum is self-incompatible and requires manipulation for achene set.
9
Stone, Harriet. "Evolution and conservation of tetraploid Euphrasia L. in Britain." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7740.
Full textAbstract:
In the UK, nearly half of the plants short listed for high conservation priority in the UK Biodiversity Action Plan are found in taxonomically complex groups. It is thought that a shift from species- to process-based conservation strategies, aimed at conserving the processes that generate diversity as opposed to simply the end product of these dynamic interactions, may benefit these groups. One group for which this strategy has been proposed is tetraploid Euphrasia. The underlying taxonomic complexity in this group is hypothesised to arise via breeding systems, hybridisation and local ecotypic adaptation. The goal of this thesis is to use morphological, ecological and molecular marker data to examine taxon limits and evolutionary processes in order to further understand the mechanisms involved in maintaining species boundaries and generating taxonomic complexity in tetraploid Euphrasia. This will not only make conservation in this group more effective, but will also provide a broader insight into some of the processes involved in plant speciation. A detailed study of two widespread, small flowered, tetraploid taxa, E. micrantha and E. scottica, showed that offspring are almost exclusively the result of self-fertilization. These taxa maintain distinctive morphologies, habitat preferences and chloroplast DNA variation throughout their range, suggesting that they represent coherent lineages within Scotland. As in other widespread inbreeding species, there are high levels of microsatellite differentiation among different populations of the same species. In northwest Scotland three complex populations of tetraploid Euphrasia were identified which comprised an array of many different morphs (recognised species, and putative hybrids). Analysis of chloroplast and microsatellite markers suggests that these different morphs represent distinct genetic groups. Within each site there is evidence both for habitat heterogeneity, and for association of morphs with this habitat variation. Intermediate morphs were not simple F1 hybrids, but are likely to have originated via hybridisation and subsequent selfing, surviving as independent recombinant lines, perhaps specialised for habitat types different from that of their progenitor parents. These stable morphs of hybrid origin could represent groups with adaptive potential that may result in the origin of a novel Euphrasia species. It will be important to further examine the processes involved in generating novel diversity in Euphrasia. For the time being, these complex populations must be recognised as sites requiring special protection within the context of a process-based conservation strategy.
10
Acuna, Carlos A. "Bahiagrass germplasm reproductive characterization and breeding at the tetraploid level." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0014399.
Full text
11
Sangu, Nomah. "Quality of grain from crosses between Australian and tetraploid wheat varieties." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/19398.
Full textAbstract:
Wheat grain proteins and starch quality are commonly affected by abiotic stress conditions. In order to reduce the effects of climate change, there is need to select heat tolerant varieties usually grown in warmer regions. The University of Sydney’s Plant Breeding Institute is working to improve heat tolerance through novel crosses between commercial Australian wheat cultivars and the ancestral tetraploid, Emmer wheat (Triticum dicoccum), which has good heat tolerance. Several potential lines have been identified in the breeding programme, but there is need to determine their grain quality attributes. The objective of this project was to study the effect of heat stress on the quality attributes of heat stressed wheat grains grown in Narrabri, NSW in 2014. The heat stressed wheat plants were sown 2 weeks after the normal planting date. Thirteen out of 200 wheat lines were chosen, based on yield, 95% of Suntop and screenings < 30%. Protein content and swelling index of glutenin was determined. SDS-PAGE was used to analyse both the soluble and insoluble protein fractions. Proteomic analysis was used to determine the identity of the proteins of interest. Total starch content, amylose content of the starch and pasting properties of both flour and starch was measured. Heat stress caused an increase in protein content and swelling index of glutenin. Qualitative differences were observed for the soluble protein fraction when SDS-PAGE gels were run. The main proteins affected by heat stress, as identified by proteomics, were serpins. Serpins are termed soluble proteins, but their occurrence in the insoluble protein fraction maybe due to the effect of heat stress which changes solubility or the ability to associate with the gluten network. Therefore, serpins may be associated with improved heat tolerance. Since serpins require strong detergents for their extraction, they may be closely linked to gluten-forming proteins and thus may have an effect on dough quality.
12
Slotte, Tanja. "Evolution of Flowering Time in the Tetraploid Capsella bursa-pastoris (Brassicaceae)." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8311.
Full text
13
Maddi, Satyanarayana. "DNA-based food authentication techniques : differentiation of tetraploid and hexaploid wheat." Thesis, Glasgow Caledonian University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517961.
Full text
14
James, Roberta Margaret. "The contribution of tetraploid cells to mid-gestation mouse aggregation chimaeras." Thesis, University of Edinburgh, 1993. http://hdl.handle.net/1842/19873.
Full textAbstract:
Mouse aggregation chimaeras were used in this study to attempt to evaluate the developmental potential of tetraploid cells in the fetus and extraembryonic membranes of mid-gestation chimaeric conceptuses. Diploid͍diploid chimaeras were generated and analysed to provide a control and general baseline for the analysis of tetraploid͍diploid chimaeras. Relationships between compositions of tissues in the diploid͍diploid chimaeras were in agreement with those already established. Tetraploid embryos were produced by electrofusion, which facilitates the fusion of adjacent blastomeres following the exposure to electric field pulses. Three genetic cell markers were chosen to allow identification of the two cell populations in chimaeric conceptuses. These were; (i) pigment in the retinal epithelial cells of the eye; (ii) electrophoretic variants of the enzyme glucose phosphate isomerase (GPI); (iii) the β-globin transgenic marker, which can be detected by <i>in situ</i> hybridization. The bulk of the analysis was performed at 12<SUP>1</SUP>/<SUB>2</SUB> days of gestation by assaying homogenized tissue for GPI. By constructing chimaeras from two embryos which were homozygous for different alleles of <i>Gpi-1</i>, it was possible to estimate the proportions of each cell type in each tissue of the chimaera. <i>In situ</i> hybridization was used to provide spatial information on the yolk sacs of the tetraploid͍diploid chimaeras. The efficiency of the electrofusion technique was tested by <i>in situ</i> hybridization, to ensure that embryos produced by the technique were uniformly tetraploid and not 4m/2n mosaics. In the tetraploid͍diploid chimaeras, the tetraploid cells contributed mainly to the primitive endoderm derivatives (yolk sac endoderm, parietal; endoderm), with very little contribution to the primitive ectoderm derivatives (fetus, amnion, yolk sac mesoderm). There was also good colonisation of the trophectoderm derivatives (trophoblast, placenta).
15
Loehrlein, Marietta Margaret 1957. "Priming techniques and size characteristics of triploid and tetraploid watermelon seed." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276845.
Full textAbstract:
Triploid and tetraploid watermelon seed are visually indistinguishable, increasing costs to growers, who cannot market the low-quality 4N melons. Efforts were made to separate 3N and 4N seeds by thickness and weight. Means in both cases were not separable. Successful seed 'priming' would be beneficial to seedless watermelon growers. Seeds from the open-pollinated 4N x 2N cross were primed in solutions of distilled water, polyethylene glycol '8000' (PEG), and potassium nitrate (KNO₃), or left untreated; treated seeds were subsequently dried for either 1 or 7 days. Seeds were scored for germination or emergence in the lab and for emergence under field conditions. Water was better than KNO₃ or PEG, but not always better than the control. One day in treatment was superior to 3 or 6 days; length of drying time was insignificant. In the field trial, treatments did not differ in emergence.
16
Silva, Paulo Minatel Gonella. "Revisão taxonômica do clado tetraploide-brasileiro de Drosera L. (Droseraceae)." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/41/41132/tde-03042013-090412/.
Full textAbstract:
O gênero Drosera (Droseraceae) compreende cerca de 200 espécies, 30 delas ocorrendo no Brasil. Nesta dissertação, é realizada a revisão taxonômica do clado tetraploide-brasileiro de Drosera, compreendendo 17 espécies e uma variedade. São apresentados e discutidos dados sobre morfologia, ecologia, distribuição geográfica e status de conservação para estas espécies, com mapas de distribuição, ilustrações, fotografias e tabelas comparativas. Os complexos D. graminifolia, D. Montana e D. villosa são discutidos nos capítulos 1, 2 e 3, respectivamente. Além disso, essas três espécies são recircunscritas com base em evidências morfológicas e de sua ecologia. Drosera ascendens, D. spiralis, D. tomentosa e suas duas variedades são restabelecidas, e D. villosa var. latifólia é elevada ao status específico. Drosera chrysolepis é lectotipificada e três novas espécies são descritas. Drosera camporupestris, D. grantsaui, D. graomogolensis, D. quartzicola, D. tentaculata e D. schwackei também pertencem ao clado e são aqui tratadas. Na seção Taxonomia, é apresentada uma chave de identificação e, no anexo II, uma lista com todos os táxons de Drosera ocorrentes no Brasil e aqui aceitos<br>The genus Drosera (Droseraceae) comprises around 200 species, 30 occurring in Brazil. In this dissertation is carried out the taxonomic revision of the Brazilian-tetraploid clade of Drosera, comprising 17 species and a variety. Here are presented and discussed data on the morphology, ecology, geographic distribution, and conservation status for these species, with distribution maps, drawings, photographs, and comparative tables. The complexes D. graminifolia, D. Montana, and D. villosa are discussed in chapters 1, 2, and 3, respectively. These three species are recircumscribed based on of morphological and ecological evidences. Drosera ascendens, D. spiralis, D. tomentosa and its two varieties are reestablished, and D. villosa var. latifolia is raised to specific rank. Drosera chrysolepis is lectotypified and three new species are described. Drosera camporupestris, D. grantsaui, D. graomogolensis, D. quartzicola, D. tentaculata, and D. schwackei also belong to this clade and are here treated. In section Taxonomy it is presented a dicotomic key and, in appendix II, a list with all Drosera taxa occurring in Brazil here accepted
17
Kuffer, Christian [Verfasser], and Stefan [Akademischer Betreuer] Jentsch. "Proliferation and arrest of human tetraploid cells / Christian Kuffer. Betreuer: Stefan Jentsch." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2015. http://d-nb.info/1072038439/34.
Full text
18
Schuck, Susan Marguerite 1957. "FLOWERING PHENOLOGY AND OUTCROSSING IN TETRAPLOID GRINDELIA CAMPORUM GREENE (GUMWEED, POLLINATION, ARIZONA)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/276715.
Full text
19
Chen, Xinwei. "Molecular mapping of genes involved in carbohydrate metabolism and fluorescent AFLP-based tagging of QTL in tetraploid potato." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=960383719.
Full text
20
Saini, Jyoti. "Genomic Analysis of Domestication-Related Traits and Stem Rust Resistance in Tetraploid Wheat." Diss., North Dakota State University, 2017. https://hdl.handle.net/10365/27459.
Full textAbstract:
Modern durum and common wheat cultivars were developed from ancient wheat ancestors by natural and artificial selection of agronomic and domestication traits, which ultimatey decreased their genetic diversity and made them more susceptible to various biotic and abiotic stresses. At present, new sources of resistance need to be introgressed into future wheat cultivars to combat the effect of the disease stem rust caused by the biotrophic fungal pathogen Puccinia graminis f.sp. tritici (Pgt). In this dissertation, I first analyzed the domestication-related traits in a tetraploid recombinant inbred line (RIL) population developed from a cross between the durum wheat line Rusty and the cultivated emmer accession PI 193883 (referred to as the RP883 population). Second, the RP883 population and a double haploid (DH) population (referred to as the LP749 population) derived from a cross between the durum cultivar Lebsock and the Triticum. turgidium ssp. carthlicum accession PI 94749, and nine durum wheat cultivars were screened with Pgt races TMLKC, TTKSK, TRTTF, and TTTTF. Domestication-related trait analysis in the RP883 population showed vernalization (Vrn-A1) and domestication (Q) genes had a pleiotrophic effect on spike length, spikelet per spike, spike compactness, and threshability. Additionally, an interaction and dosage effect of three free-threshing trait governing loci, teneacious glume Tg2A and Tg2B, and q, revealed that mutation in all three loci are required to attain complete free threshability. The stem rust analysis done in the RP883 population showed two Sr gene regions conferring resistance against TMLKC, TTKSK, and TRTTF: one novel gene region on chromosome 2BL (Sr883) and likely a new allele or gene residing in close proximity to the Sr13 gene on 6AL. The second stem rust study using the LP749 population and nine durum wheat cultivars showed that most likely the U.S. durum germplasm carries the four major Sr genes, Sr7a (4AL), Sr8155B1 (6AS), Sr13 (6AL), and likely Sr9e (2BL) against TTKSK, TRTTF, and TTTTF. In conclusion, results obtained from this domestication study provide knowledge about different stages in wheat evolution. Both stem rust studies revealed genetic diversity in the tetraploid wheat gene pool and indicate their utility in future breeding programs.<br>USDA-Agricultural Research Service
21
Ritter, Kate. "Fecundity of Triploid Eastern Oyster (Crassostrea virginica) as a Function of Tetraploid Lineage." W&M ScholarWorks, 2019. https://scholarworks.wm.edu/etd/1582642221.
Full textAbstract:
Rapid growth rate and partial sterility have made triploid eastern oysters (Crassostrea virginica) the most popular crop variety for the Virginia oyster aquaculture industry, typically comprising greater than 90% of larvae and juvenile sales. Triploid advantages, however, sometimes come with the disadvantage of higher mortality in late spring and early summer, dubbed “triploid mortality.” In recent years, farms up and down the East Coast, especially Maryland and south into the Gulf of Mexico have experienced triploid mortality. Some of the reports include observations of elevated triploid fecundity. Triploid oysters are created by crossing tetraploids to diploids, and much of the commercial broodstock is acquired through the Virginia Institute of Marine Science Aquaculture Genetics and Breeding Technology Center (ABC). Tetraploid oysters are created from fecund triploid females and propagated favoring the most fertile tetraploids. We hypothesized that heritable fertility may be transferred to the commercial product, possibly yielding fertile triploid oysters. To investigate this possibility, twelve half-sibling families were produced by crossing individual tetraploid males with aliquots from a pooled source of eggs from diploid females. Tetraploid males came from tetraploid lines bred for one, two, five, or eight generations. Two replicates of each family were deployed to two sites: a site known for episodes of triploid mortality on the Eastern Shore of Chesapeake Bay, and at a control site in the Rappahannock River. Temperature and salinity exhibited typical patterns at both sites while oysters were raised to market size. When compared to the control site, cumulative mortality of triploid oysters at the Eastern Shore location was significantly higher, with significantly lower growth rate and fecundity; the latter measured by direct egg counts at peak ripeness. Diploid oysters performed similarly at both sites and exhibited significantly greater fecundity than triploids. Fecundity differed significantly among several triploid families based upon paternal lineage, but fecundity did not vary as a function of tetraploid lineage.
22
Fogelström, Elsa. "Herbivores, pollinators and selection on flowering time in tetraploid and octoploid Cardamine pratensis." Thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-88100.
Full textAbstract:
Repeated polyploidization events are thought to be among the most important causes of sympatric speciation throughout evolutionary time. Changes in phenology and trait expressions that arise in polyploids have been shown to affect plant interactions with insect herbivores and pollinators. If these interactions are changed, selection subsequent to the polyploidization event could contribute to further divergence, or increased similarity, of cytotypes. This study was conducted to investigate plant interactions with insect herbivores and pollinators and patterns of selection in tetraploid and octoploid Cardamine pratensis L. (Brassicaceae), and to answer the following questions: i) Is there phenotypic selection on flowering phenology and number of flowers? ii) Is pollen limitation or herbivory most important for variation in reproductive output? iii) During what stages of ovary and ovule development do variation in fitness mainly arise? iv) Can the intensity of interactions be linked to phenology and number of flowers, suggesting that selection is mediated by pollen limitation or herbivory? v) Do intensity of interactions, and of interaction-mediated selection, differ between ploidy levels? From a combination of an observational study of herbivory and a hand pollination experiment, selection was found for earlier flowering in both subspecies. Intensity of herbivory was an important determinant of plant reproductive success, while hand pollination had little effect. Positive effects of flowering time on intensity of herbivory suggest that selection for earlier flowering was mediated by herbivores. Tetraploids initiated flowering later and suffered from more intense herbivory than did octoploids. The direction of selection was similar in both subspecies. However, differences strength of selection and intensity of herbivory suggest that there is a possibility of selection for their further divergence.<br>Polyploidisering anses vara en av de viktigaste orsakerna till artbildning inom populationer. Skillnader i blomningskaraktärer, såsom fenologi och blomantal, som uppstår i och med polyploidiseringen har visat sig påverka växters interaktioner med såväl pollinatörer som herbivorer. Förändringar i växt-insektsinteraktioner till följd av polyploidiseringen kan leda till selektion för ökade skillnader, eller likheter, mellan cytotyper. Studiens syfte var att undersöka växters interaktioner med insekter i form av pollinatörer och herbivorer, samt att undersöka selektionsmönster hos tetraploida och oktoploida Cardamine pratensis L. (Brassicaceae). Jag ville även besvara följande frågor: i) Sker selektion på blomningstid och blomantal? ii) Vilken växt-insektsinteraktion är viktigast för variation i reproduktionsframgång? iii) Under vilka utvecklingsstadier uppstår den största variationen i fitness? iv) Kan intensiteten av interaktionerna kopplas till blomningsfenologi och blomantal, vilket skulle indikera att selektion förmedlas genom pollenbegränsning eller herbivori? v) Skiljer sig styrkan av interaktionerna, och av interaktionsförmedlad selektion, mellan ploidinivåer? Studien utformades som en kombination av en observationsstudie av herbivori och ett handpollineringsexperiment, och jag fann selektion för tidigare blomning hos de två underarterna. Reproduktionsframgång styrdes av herbivori snarare än pollenbegränsing. Förlust av potentiell fitness genom att fröämnen inte utvecklades till frön var den faktor som starkast påverkade variation i fitness, och detta var också den fas i utvecklingen som bidrog i störst utsträckning till kvantitativ förlust av fitness. Ett positivt samband mellan blomningsfenologi och herbivoriintensitet indikerar att selektion för blomningstid var förmedlad av herbivorer. Tetraploider blommade senare och utsattes för mer intensiva herbivorattacker än oktoploider. Detta, samt skillnader i selektionsstyrka, indikerar att selektion skulle kunna leda till ökad divergens av underarterna.
23
Baack, Eric Jon. "An investigation of ecological factors affecting tetraploid speciation in snow buttercups (Ranunculus adoneus) (Ranunculaceae) /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
Full text
24
SHERMAN, RICHARD ALAN. "CHROMOSOMAL INHERITANCE IN A BACKCROSS PROGRAM BETWEEN A HEXAPLOID COTTON LINE AND TETRAPLOID COTTON (CYTOGENETICS)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183873.
Full textAbstract:
A breeding program was begun to transfer the caducous bract trait from the wild cotton diploid species Gossypium armourianum Kearney (D genome, 2n = 26) to the cultivated tetraploid species G. hirsutum (AD genomes, 2n = 4x = 52). The sterile triploids were then doubled with colchicine to obtain fertile hexaploid plants. These plants and their open pollinated progeny varied in their chromosome number from 73 to 82 chromosomes, the majority being the expected 78 chromosomes. Chromosome associations included bivalents, trivalents, quadrivalents, and hexavalents. The caducous bract trait varied from being similar to each parent species to intermediate expression. Backcrossed to G. hirsutum, progeny with 61 to 67 chromosomes were obtained with associations including frequent trivalents, quadrivalents, and one hexavalent. The caducous bract trait was not expressed in most plants and only variable in others. Progeny from open pollination or backcrossing these plants gave chromosome numbers closer to the tetraploid parent, with ranges of 56 to 64 chromosomes in open pollinated progeny and 52 to 58 for backcrossed plants. Again, the caducous bract trait was variable, possibly due to the influence of the A and D genomes of the New World cottons. Tetraploids recovered from the progeny had bivalent pairing and chiasma frequencies similar to G. hirsutum. Further backcrossing is hoped to increase the expression of the caducous bract trait.
25
Wall, Sarah. "The role of B chromosomes in the genetic system of a tetraploid grass (Koeleria cristata L.)." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237468.
Full text
26
Skoneczka, Jeffrey Allen. "Inheritance and expression of Cry3Aa and PVY-O coat protein transgenes in diploid and tetraploid potato." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/10068.
Full textAbstract:
The potential benefits of plant genetic engineering for disease and pest resistance have been widely acknowledged in many studies, and although genetically modified crops are still encountering public wariness, these benefits warrant continued exploration. Because of its intrinsic economic benefits, the development of true potato seed (TPS) cropping systems has been instituted in many regions of the world. The incorporation of transgenic resistance could further the economic gain of farmers who are seeking ways to sustain their livelihood in the most efficient way possible. It is, however, largely unresearched how sexual hybridization of a transgenic crop would affect the behavior of a transgene in the resultant progeny. In the initial part of this study, transgenic lines were developed with a Cry3Aa transgene. These plants were then used in 4x-4x reciprocal crosses and 4x-2x hybridization schemes to determine the stability of the transgene after sexual hybridization. There was no observed parent of origin effect on transgene expression; however, a highly significant, non-mendelian inheritance of the Cry3Aa transgene was seen in the maternally inherited transgene of one set of progeny from a reciprocal cross. Additional transgenic lines of potato were developed with a PVY-O coat protein transgene. These plants were challenged with PVY-O and monitored for symptoms visually and for virus serologically. One transgenic line exhibited complete resistance to PVY-O while two others showed a delay in symptom occurrence. Further examination of the expression levels of the PVY-O coat protein transgene will be necessary to determine the type and usefulness of the observed resistance.<br>Master of Science
27
Loehrlein, M. M., and D. T. Ray. "Techniques for Separating Tetraploid and Triploid Watermelon Seed and Effects of Some Priming Treatments on Germinaiton." College of Agriculture, University of Arizona (Tucson, AZ), 1988. http://hdl.handle.net/10150/214150.
Full textAbstract:
Seeds of the commercial cultivar for seedless watermelons, TriX313, were separated into groups based on thickness in one experiment and on weight in another. Number of triploids and tetraploids were recorded for each category. There were no significant differences in ploidy levels based on either weight or seed thickness. Seeds from this same cultivar were treated with priming solutions of polyethylene glycol (PEG 8000), KNO3, and distilled water for three lengths of time (1,3, or 6 days). The seed was subsequently air-dried for 1 or 7 days and then tested for germination and emergence.
28
Liu, Chao-yin. "Variation and genetic control of prolamins in tetraploid wheats and their association with quality in durum wheat." Title page, contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phl783.pdf.
Full text
29
Whitebrook, J. "Heavy metal tolerance and the distribution in SW Britain of the diploid and tetraploid cytotypes of Leucanthemum vulgare Lam. (Compositae)." Thesis, University of Bristol, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372036.
Full text
30
Ormanbekova, Danara <1987>. "Durum wheat gene annotation and selection signature detection in the tetraploid wheat germplasm from wild emmer to modern durum wheat." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amsdottorato.unibo.it/8908/1/Tesi_Dottorato_Ormanbekova_Danara.pdf.
Full textAbstract:
The domestication of the wild emmer wheat nearly 10,000 years ago in the Fertile Crescent lead to the evolution of the free-threshing and easy to harvest tetraploid Triticum durum wheat. We annotated the gene models and assessed the gene expression pattern of a 10.45-gigabase assembly of durum wheat cultivar Svevo and predicted 66,559 high-confidence genes with 95.8% expression evidence. 75.0, 70.5 and 74.5% of high-confidence genes were expressed in grain, leaf and root tissues, respectively, of the 13 elite worldwide durum wheat varieties. Additionally, we annotated 1,487 loci associated with NBS-LRR genes that are prominently involved in signaling and plant disease resistance. Using the Global Tetraploid wheat Collection composed of 1,856 accessions representing the four principal germplasm groups involved in the tetraploid domestication and selection history, we detected the genetic diversity and selection signature regions associated with wild emmer domestication and durum wheat evolution on the pericentromeric regions of chromosome groups 2, 4, 6 and on chromosomes 1A, 7B. Several diversity reduction and selection signature peaks overlapped with loci associated with domestication, disease resistance, yellow pigment content and seed dormancy. Population structure of the tetraploid diversity panel assessed by ADMIXTURE subdivided wild emmer (WEW) in two main populations, domesticated emmer (DEW) and durum landraces (DWL) in six populations each, and durum cultivars (DWC) in five subpopulations. The modern durum wheat germplasm showed the highest relationship to the North African and Turkey to Transcaucasia DWL populations, while the Ethiopian and T. turanicum populations were the most differentiated with a minimal contribution to the modern durum germplasm. The selection signature detection provided an insight into the dynamics of tetraploid wheat domestication and selection. The reference assembly of durum wheat is a valuable resource directed to accelerate the progress and accuracy of genome-assisted advancement of modern wheat.
31
Naran, D., P. H. Skelton, and Martin Herrer Villet. "Karyology of the redfin minnows, genus Pseudobarbus Smith, 1841 (Teleostei: Cyprinidae): one of the evolutionarily tetraploid lineages of South African barbines." African Zoology, 2006. http://hdl.handle.net/10962/d1008063.
Full textAbstract:
The karyotypes of six species of Pseudobarbus Smith, 1841, namely P. afer (Peters, 1864), P. asper (Boulenger, 1911), P. burchelli Smith, 1841, P. burgi (Boulenger, 1911), P. phlegethon (Barnard, 1938) and P. tenuis (Barnard, 1938), were examined by conventional Giemsa staining and described. All six karyotypes have 2n = 100 chromosomes, dominated by biarmed chromosomes, as does the only other member of the genus, P. quathlambae (Barnard, 1938). Sex-related intraspecific karyotype variation was not found. The shared chromosome numbers and general similarity of the karyotypes (FN = 186–192) provide a new synapomorphy to support their monophyly, which is already indicated by anatomical and mtDNA markers. Karyotype evolution within the genus has been accompanied by chromosomal inversions and centromeric shifts. Comparison of the diploid number found in Pseudobarbus with other African barbine cyprinines, which have in the region of 2n=50 and lower FNs, suggests a tetraploid evolutionary origin of the genus, possibly by allotetraploidy.
32
De, Jesus Larry. "Effects of artificial polyploidy in transformed roots of Artemisia annua L." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0424103-155547.
Full text
33
Sederberg, Maria C. "Physical Mapping of Ribosomal Genes in New World Members of the Genus Chenopodium Using Fluorescence in Situ Hybridization." BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/1629.
Full textAbstract:
The genus Chenopodium contains many economically important species in the New World, but is relatively understudied and poorly understood, especially in terms of evolutionary relationships. A better understanding of the structure of this genus could significantly help in breeding efforts on its cultivated members, notably the tetraploid C. quinoa and also certain varieties of C. berlandieri, also tetraploid. Of special concern is determining which diploid weed species are the most likely ancestors for C. quinoa, C. berlandieri, and the other tetraploid members of subsection Cellulata. The phylogeny can be understood in part by examining the ribosomal RNA loci and observing how many copies of the 5S and 45S loci each New World species contains. In this work, the 5S and 45S ribosomal RNA loci are characterized by means of fluorescence in situ hybridization in 23 Chenopodium species collected in the New World, with the 5S locus labeled red and the 45S locus labeled green. Based on these results, the pool of most likely candidate ancestor species for C. quinoa and C. berlandieri includes C. fremontii, C. incanum, C. neomexicanum, and C. watsonii.
34
Oliveira, Hugo Rafael Cardoso. "Archaeogenetics and the spread of agriculture in the Iberian Peninsula and Northwest Africa : a study of genetic variation within tetraploid and diploid wheats." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609794.
Full text
35
Hennig, Anne [Verfasser], Andrea [Akademischer Betreuer] [Gutachter] Polle, and Reiner [Gutachter] Finkeldey. "Drought stress response of tetraploid hybrid aspen (Populus tremula L. x P. tremuloides Michx.) of protoplast fusion experiments) / Anne Hennig. Betreuer: Andrea Polle. Gutachter: Andrea Polle ; Reiner Finkeldey." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://d-nb.info/1102535656/34.
Full text
36
Stewart, Alan V. "Plant breeding aspects of ryegrasses (Lolium sp.) infected with endophytic fungi." Phd thesis, University of Canterbury. Lincoln College, 1987. http://theses.lincoln.ac.nz/public/adt-NZLIU20071005.172250/.
Full textAbstract:
Some aspects of the presence of systemic endophytic fungi in agriculturally important New Zealand grasses were studied in relation to plant breeding. Seedling resistance to adult Argentine stem weevil feeding in perennial ryegrass, Italian ryegrass and tall fescue was found to be related to the presence of their respective Acremonium endophytes in the seed rather than to plant genetic resistance. In addition a study of perennial ryegrass revealed that this resistance was independent of endophyte viability. The seedling resistance conferred by the endophyte of Italian ryegrass was found to be beneficial for field establishment. This endophyte differs from that in perennial ryegrass and tall fescue in that it does not confer resistance to Argentine stem weevil on mature plants, but only on seedlings. The extent of plant genetic seedling tolerance to adult Argentine stem weevil feeding was limited to broad inter-specific differences, with tall fescue more tolerant than perennial ryegrass and both of these more tolerant than Italian ryegrass. This ranking corresponds with previous observations on feeding preference on mature plants. A study of factors affecting the concentration of endophyte mycelia in infected seed of perennial ryegrass revealed that plant genetic factors had little effect. The major factors studied were: 1) the endophyte concentration in the maternal parent plant directly influenced the endophyte concentration in the seed. 2) nitrogen fertilizer applications to a seed crop reduced the concentration of mycelia in the seed, with earlier applications having a greater effect. 3) application of the fungicide propiconazole (Tilt) to a seed crop reduced the endophyte concentration in the seed. 4) the endophyte concentration in the seed was found to directly influence the endophyte concentration in seedlings, six month old plants and that of seed harvested from a first year seed crop. As there have been no previous reports of tetraploid perennial ryegrass cultivars with endophyte an experiment was conducted to determine if these could be developed by the standard procedure of colchicine treatment. The results revealed that endophyte was retained following colchicine treatment.
37
Rosche, Christoph [Verfasser], Isabell [Akademischer Betreuer] Hensen, Heinz [Akademischer Betreuer] Müller-Schärer, and Marie [Akademischer Betreuer] Jasieniuk. "The potential of polyploidy to counteract the negative consequences of demographic disequilibria in colonizing populations : empirical insights from diploid and tetraploid Centaurea stoebe / Christoph Rosche ; Isabell Hensen, Heinz Müller-Schärer, Marie Jasieniuk." Halle, 2016. http://d-nb.info/1117028291/34.
Full text
38
Oliveira, Stéfanie Cristina de. "Poliploidização e calogênese in vitro de Jatropha curcas L." Universidade Federal do Espírito Santo, 2012. http://repositorio.ufes.br/handle/10/6567.
Full textAbstract:
Made available in DSpace on 2016-12-23T14:37:31Z (GMT). No. of bitstreams: 1
Stefanie Cristina Oliveira.pdf: 1100238 bytes, checksum: e4200efbe53a66bdaa4fc82fbfac51ed (MD5)
Previous issue date: 2012-07-27<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>O uso de bioenergia tem sido apontado como uma estratégia para diminuição da utilização de combustíveis fósseis. Fundamentado nesse fato, muitos países, incluindo o Brasil, aumentaram os esforços para financiar pesquisas com espécies
vegetais produtoras de biocombustíveis. Dentre essas espécies, Jatropha curcas L. destaca-se pelo alto potencial para produção de óleo. Visando à propagação clonal e massal de acessos elite de J. curcas, técnicas de cultura de tecidos têm sido aplicadas. Entretanto, diferentes autores frisaram a necessidade de ampliação de estudos envolvendo ferramentas da cultura de tecidos vegetais, dentre elas a poliploidização in vitro. A indução de poliploides in vitro é uma importante ferramenta no melhoramento genético de plantas, por possibilitar a obtenção de maior variabilidade de materiais com possíveis incrementos de características agronômicas desejáveis. Nesse sentindo, um dos objetivos deste trabalho foi estabelecer um protocolo de indução in vitro de plântulas poliploides da variedade / Gonçalo/ (2C = 0.85 pg, 2n = 2x = 22 cromossomos). Os resultados de citometria de fluxo evidenciaram que tetraploides e mixoploides foram obtidos a partir de ápices caulinares tratados com diferentes concentrações de colchicina e tempos de exposição. Fundamentado em três parâmetros (número de plântulas sobreviventes, tetraploides e mixoploides), o tratamento envolvendo 0,5 mM de colchicina a um pulso de 96 horas foi considerado o mais adequado. Com base nesse resultado, um
segundo experimento de poliploidização foi realizado somente com a dosagem de 0,5 mM com pulsos de 96, 120, 144 e 168 horas. Os resultados confirmaram que a concentração de 0,5 mM por 96 horas é ideal para indução de tetraploides de J.
curcas / Gonçalo/ . Plântulas mixoploides também foram encontradas nos tratamentos com0,5 mM de colchicina aos pulsos de 96, 120 e 144 horas. Visto a relevância da
propagação clonal e massal de acessos elite de J. curcas, inclusive das plântulas poliploides obtidas no primeiro estudo, o presente trabalho também teve como objetivo induzir a calogênese in vitro a partir de explantes foliares. Os resultados
mostraram que a combinação ácido 2,4-diclorofenoxiacético (2,4-D)/cinetina (KN) promoveu maior número de explantes com calos friáveis quando comparado à combinação ácido indol-3-butírico (AIB)/KN. Dessa forma, o procedimento
envolvendo a combinação auxina/citocinina é fundamental para gerar calos friáveis, os quais representam a base para estabelecimento de um sistema embriogênico in vitro de acessos elite. Pela primeira vez, um sistema de cultura de tecidos foi adaptado para indução, propagação e recuperação de tetraploides e mixoploides de J. curcas / Gonçalo/ . Além disso, os dados gerados contribuem para criação e
ampliação de bancos de germoplasma in vitro da espécie<br>The use of bioenergy has been suggested as a strategy for reducing the utilization of fossil fuels. Thereafter, many countries, including Brazil, have increased efforts to fund the research of plant species for biofuel production. Among these species, Jatropha curcas L. stands out mainly due to its high potential for oil production. Thus, tissue culture techniques have been applied aiming at the mass and clonal propagation of J. curcas elite lines. However, different authors have emphasized the necessity of expanding studies that involve plant tissue culture tools such as in vitro polyploidization. In this sense, the present study sought to establish a protocol for in vitro induction of polyploid seedlings from shoot tips of the variety Gonzalo (2C = 0.85 pg, 2n = 2x = 22 chromosomes). Flow cytometry revealed mixoploids and tetraploids obtained from shoot tips treated with different colchicine concentrations and exposure times. Based on three criteria (survival rate of the explants, and numbers of tetraploid and mixoploid plantlets), the treatment with 0.5 mM colchicine in a 96 hour pulse was statistically considered the most appropriate. Based on these data, a second polyploidization experiment was carried out, using a dosage of 0.5 mM colchicine in pulses of 96, 120, 144 and 168 hours. The results confirmed that the concentration of 0.5 mM for 96 hours was the ideal treatment for J. curcas Gonçalo tetraploid induction. Mixoploid seedlings were also detected in the treatments with 0.5 mM colchicine in pulses of 96, 120 and 144 hours. Considering the relevance of mass and clonal multiplication of elite J. curcas accessions, and the polyploid seedlings obtained in the first investigation, this study further aimed to establish in vitro callogenesis from leaf explants. The results showed that the combination of 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin (Kn) provided
greater number of explants with friable calli in relation to the combination indol-3-butyric acid (IBA) and Kn. Thus, 2,4-D/Kn was the treatment of choice to generate friable calli, which are essential for somatic embryogenesis. Ultimately, a tissue culture system was adapted for induction, propagation and recovery of in vitro tetraploids from the J. curcas variety Gonçalo, as well as other inbred lines. Besides providing a new protocol for polyploidy generation, this study also contributed to the germplasm of J. curcas and the achievement of genetic variability through obtainment of tetraploid and mixoploid seedlings
39
Zale, Peter J. "GERMPLASM COLLECTION, CHARACTERIZATION, AND ENHANCEMENT OF EASTERN PHLOX SPECIES." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417694536.
Full text
40
BELOT, JEAN-MICHEL. "La tetraploidie en mosaique : a propos d'une observation." Lille 2, 1994. http://www.theses.fr/1994LIL2M002.
Full text
41
Kuznetsova, Anastasia. "Transient tetraploidy as a route to chromosomal instability." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-168126.
Full text
42
Nicholson, Joshua Miles. "The effects of chromosome number changes on mitotic fidelity and karyotype stability." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/52957.
Full textAbstract:
The correct number of chromosomes is important for the maintenance of healthy cells and organisms. Maintenance of a correct chromosome number depends on the accurate distribution of chromosomes to the daughter cells during cell division, and errors in chromosome segregation result in abnormal chromosome numbers, or aneuploidy. Aneuploidy is typically associated with deleterious effects on organismal and cellular fitness; however, aneuploidy has also been associated with enhanced cellular growth in certain contexts, such as cancer. Another type of deviation from the normal chromosome number can occur when entire sets of chromosomes are added to the normal (diploid) chromosome number, resulting in polyploidy. Whereas polyploidy is found in certain normal tissues and organisms, tetraploidy (four sets of chromosomes) is associated with a number of precancerous lesions and is believed to promote aneuploidy and tumorigenesis. While it is clear that chromosome mis-segregation causes aneuploidy, the effect of aneuploidy on chromosome segregation is less clear. Similarly, it is unclear whether and how tetraploidy may affect chromosome segregation. The work described here shows that aneuploidy can cause chromosome mis-segregation and induces chromosome-specific phenotypic effects. In contrast, tetraploidy does not per se induce chromosome mis-segregation, but enables the accumulation of aneuploidy thanks to a "genetic buffer" effect that allows tetraploid cells to tolerate aneuploidy better than diploid cells.<br>Ph. D.
43
Darp, Revati A. "Insights into the Role of Oncogenic BRAF in Tetraploidy and Melanoma Initiation." eScholarship@UMMS, 2021. https://escholarship.umassmed.edu/gsbs_diss/1129.
Full textAbstract:
Melanoma, the most lethal form of skin cancer, arises from altered cells in the melanocyte lineage, but the mechanisms by which these cells progress to melanoma are unknown. To understand the early cellular events that contribute to melanoma formation, we examined melanocytes in melanoma-prone zebrafish strains expressing BRAFV600E, the most common oncogenic form of the BRAF kinase that is mutated in nearly 50% of human melanomas. We found that, unlike wild-type melanocytes, melanocytes in transgenic BRAFV600Eanimals were binucleate and tetraploid. Furthermore, melanocytes in p53-deficient transgenic BRAFV600Eanimals exhibited 8N and greater DNA content, suggesting bypass of a p53-dependent arrest that stops cell cycle progression of tetraploid melanocytes. These data implicate tetraploids generated by increased BRAF pathway activity as contributors to melanoma initiation. Previous studies have used artificial means of generating tetraploids, raising the question of how these cells arise during actual tumor development. To gain insight into the mechanism by which BRAFV600E generates binucleate, tetraploid cells, we established an in vitro model by which such cells are generated following BRAFV600E expression. We demonstrate thatBRAFV600E-generated tetraploids arise via cytokinesis failure during mitosis due to reduced activity of the small GTPase RhoA. We also establish that oncogene-induced centrosome amplification in the G1/S phase of the cell cycle and subsequent increase in the activity of the small GTPase Rac1, partially contribute to this phenotype. These data are of significance as recent studies have shown that aneuploid progeny of tetraploid cells can be intermediates in tumor development, and deep sequencing data suggest that at least one third of melanomas and other solid tumors have undergone a whole genome doubling event during their progression. Taken together, our melanoma-prone zebrafish model and in vitro data suggest a role for BRAFV600E-inducedtetraploidy in the genesis of melanomas. To our knowledge, this is the first in vivo model showing spontaneous rise of tetraploid cells that can give rise to tumors. This novel role of the BRAF oncogene may contribute to tumorigenesis in a broader context.
44
Kuznetsova, Anastasia [Verfasser], and Stefan [Akademischer Betreuer] Jentsch. "Transient tetraploidy as a route to chromosomal instability / Anastasia Kuznetsova. Betreuer: Stefan Jentsch." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1049393279/34.
Full text
45
Gouvea, Ediene Galdino de. "Construção de mapas genéticos para os genomas A, B e tetraploide de Arachis spp." reponame:Repositório Institucional da UnB, 2012. http://repositorio.unb.br/handle/10482/10698.
Full textAbstract:
Dissertação (mestrado)—Universidade de Brasília, Programa de Pós-Graduação em Botânica, 2012.<br>Submitted by Jaqueline Ferreira de Souza (jaquefs.braz@gmail.com) on 2012-06-14T11:03:51Z
No. of bitstreams: 1
2012_EdieneGaldinodeGouvea.pdf: 1348445 bytes, checksum: eef908d13b7d1ad7bb9fd1bcfbf8ca24 (MD5)<br>Approved for entry into archive by Jaqueline Ferreira de Souza(jaquefs.braz@gmail.com) on 2012-06-14T11:04:04Z (GMT) No. of bitstreams: 1
2012_EdieneGaldinodeGouvea.pdf: 1348445 bytes, checksum: eef908d13b7d1ad7bb9fd1bcfbf8ca24 (MD5)<br>Made available in DSpace on 2012-06-14T11:04:04Z (GMT). No. of bitstreams: 1
2012_EdieneGaldinodeGouvea.pdf: 1348445 bytes, checksum: eef908d13b7d1ad7bb9fd1bcfbf8ca24 (MD5)<br>O amendoim cultivado (Arachis hypogaea L.) é um grão de grande importância econômica e nutricional, e um dos alimentos humanos mais nutritivos e de fácil digestão, por ter o grão rico em óleo e proteínas. Espécies silvestres de Arachis são importantes fontes de genes que controlam características de interesse para o amendoim. O mapeamento genético é de grande utilidade no auxílio a programas de melhoramento de plantas, possibilitando o mapeamento de locos que controlam características quantitativas, ou QTL‟s (Quantitative Trait Loci); também são usados em estudos de sintenia ou mapeamento comparativo e clonagem de genes. Nesse trabalho foram desenvolvidos três mapas genéticos baseados em populações RIL: um referente ao genoma A, um referente ao genoma B e por último um para o genoma tetraploide do amendoim. Para o mapa A foram utilizados diversos tipos de marcadores, como microssatélites, marcadores âncoras, SNPs e RGAs; já nos mapas B e tetraploide foram utilizados somente marcadores microssatélites. Em geral, os mapas obtidos apresentaram tamanhos e número de grupos de ligação semelhantes aos mapas já publicados. O mapa de genoma A apresentou comprimento total de 1036 cM com 870 marcadores distribuídos em 10 grupos de ligação. O mapa de genoma B teve comprimento total de 560,3 cM, 10 grupos de ligação e 147 marcadores mapeados e o mapa tetraploide 1066 cM, com 210 marcadores mapeados em 21 grupos de ligação. Muitos dos marcadores utilizados são gênicos e de cópias únicas e são de grande importância para estudos de genômica comparativa, e apresentam grande chance de estarem ligados a genes de interesse. Além disso, foi realizado um estudo de sintenia entre esses mapas, que evidenciou bastante semelhança entre eles. Os mapas genéticos moderadamente saturados representam um considerável aumento na capacidade de mapear genes úteis e utilizar a seleção assistida por marcadores nos programas de melhoramento do amendoim. ______________________________________________________________________________ ABSTRACT<br>The cultivated peanut (Arachis hypogaea L.) is a grain of great nutritional and economic importance, and it is one of the most nutritious and digestible human food available, as it is rich in oil and protein. Wild species of Arachis are important sources of genes that control interesting traits for the cultivated peanut. Genetic mapping is a useful tool in plant breeding programs, enabling the mapping of loci controlling quantitative, polygenic or traits with complex inheritance, called QTL's (Quantitative Trait Loci); it is also used in studies of synteny or comparative mapping and gene cloning. In this work three genetic maps were developed based on RIL populations: one for the A genome, one for the B genome and one for the tetraploid peanut genome. For the A map we used different types of markers such as microsatellite, anchor, SNPs and RGA markers, whereas in the B and tetraploid maps only microsatellite markers were used. In general, the maps had size and number of linkage groups similar to already published maps. The A genome map showed a total size of 1036 cM, with 870 markers distributed into 10 linkage groups. The B genome map had a total size of 560,3 cM, 10 linkage groups and 147 markers mapped, while the map for tetraploid genome showed 1066 cM, with 210 markers mapped into 21 linkage groups. Many of the markers are single copy genes and of great importance to comparative genomics studies, and with a great chance of being linked to genes of interest. Furthermore, a synteny study between these maps showed a great similarity between them. The moderately saturated genetic maps represent a considerable increase in the ability to map useful genes and to use marker-assisted selection in peanut breeding programs.
46
Grieger, Patrick. "Untersuchungen zur Züchtung variegater Pelargonium x zonale-Hybriden auf tetraploider Stufe." Doctoral thesis, Humboldt-Universität zu Berlin, Landwirtschaftlich-Gärtnerische Fakultät, 2007. http://dx.doi.org/10.18452/15673.
Full textAbstract:
Die vorliegende Arbeit befasst sich mit züchtungsmethodischen Untersuchungen zur Schaffung blattvariegater Pelargonium x zonale-Hybriden auf tetraploidem Leistungsstand. Basierend auf dem Wirkstoff Trifluralin konnte eine effektive Behandlungsvariante zur somatischen Polyploidisierung periklinalchimärischer Pelargonium x zonale-Klone etabliert werden. Unter Ausnutzung biparentaler Erbgänge wurden fünf ausgewählte Plasmotypen an das Leistungsniveau moderner Sortimente herangeführt. Daneben erbrachten Kreuzungen innerhalb der Sektion Ciconium hybridvariegate F1-Pflanzen. Die Möglichkeit der Ausnutzung von Kern-Plasma-Wechselwirkungen in der Pelargonienzüchtung wird diskutiert. Im Hinblick auf den Aufbau eines Protoplastenregenerationssystems konnten Zellsuspensionskulturen etabliert werden. Im Anschluss an enzymatische Verdauungen wurde die Regeneration von Kallus beobachtet. Variegate Pflanzen aus Mutationsversuchen mit NMH (Nitroso-Methyl-Harnstoff), einer weiteren experimentellen Variante, erwiesen sich als steril, so dass eine weiterführende Züchtungsarbeit auf diesem Weg bisher noch nicht möglich war<br>The study analyzes breeding schemes concerning the development of variegated tetraploid Pelargonium x zonale-hybrids (Pelargonium x hortorum). With a focus on practical relevance breeding methods for periclinal chimeric leaf patterns are discussed. Trifluralin-induced tetraploid Pelargonium x zonale-hybrids were successfully crossed with modern cultivars. Via biparental mode of inheritance five defined plasmotypes were transfered to the karyological background of current high-performance Pelargonium series. In a crossing-program within the section Ciconium hybrid-variegation was detected. The possibility of using nucleo-plasmatic interactions in developing new Pelargonium cultivars is discussed. First steps concerning a biotechnological approach to create variegated plants included the establishment of cell-suspension-cultures as the base for a protoplast regeneration system. Following the enzymatic digestion of Pelargonium-liquid cultures up to now, callus regeneration was achieved. Variegated plants resulting from mutagenic treatments with NMU (Nitroso-methylurea) proved to be sterile.
47
Burton, Tracy Lynn. "Relationships between diploids, tetraploids and their triploid hybrids, implications for evolution of polyploidy in plants." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0019/NQ55619.pdf.
Full text
48
Carrillo, Maurício [UNESP]. "Indução à tetraploidia em tilápia nilótica Oreochromis niloticus utilizando-se choque térmico." Universidade Estadual Paulista (UNESP), 2004. http://hdl.handle.net/11449/144121.
Full textAbstract:
Made available in DSpace on 2016-09-27T13:40:11Z (GMT). No. of bitstreams: 0
Previous issue date: 2004-06-02. Added 1 bitstream(s) on 2016-09-27T13:45:31Z : No. of bitstreams: 1
000224725.pdf: 617563 bytes, checksum: 40034ec7e8e2119ebc589d8e72abd28c (MD5)<br>A indução à tetraploidia em tilápia do Nilo foi realizada mediante a aplicação de choques térmicos quentes a uma temperatura de 41º C, utilizando-se três tempos pós-fertilização (P.F.). No 1º ensaio, utilizaram-se tempos de P.F. de 50, 55 e 60 minutos e duração de 2 e de 5 minutos e no 2º de 24, 27 e 30 minutos, com duração de 5 e de 8 minutos. Para a coleta dos gametas, somente as fêmeas que apresentaram características secundárias de maturação foram induzidas artificialmente, por meio de injeções intramusculares com Gonadotrofina Coriônica Humana (HCG). Os machos não foram induzidos pela facilidade na liberação do sêmen. Depois da aplicação dos tratamentos os animais foram mantidos ate os quatro meses de idade momento no qual, foi comprovada a eficácia dos tratamentos mediante a contagem do número de cromossomos em preparações mitóticas 'in vivo de células de rim e a cultura in vitro de linfócitos. Foram encontradas diferenças significativas (P< 0.05) nos tempos de duração do choque para os dois ensaios, em relação à estimativa das taxas de sobrevivência as quais foram inversamente dependentes da temperatura. O resultado das análises da contagem de cromossomos em todos os tratamentos, mostrou um número modal normal diplóide (2n=44), indicando que a não obtenção de tilápias tetraploides deva-se provavelmente à idade dos animais em que foi feita as provas<br>The induction of the tetraploid in Nile tilapia was carried through means of application of hot thermal shoks to a temperature of 41,0 ºC, using it three times after-fertilization (A.F.). On the 1º assay A.P., times of 50, 55 and 60 minutes have been used and duration of 2 and 5 minutes and on the 2º of 24,27 and 30 minutes, with duration of 5 and 8 minutes. For the collection of gametes, the females that preented secondary characteristics of maduration had only been induced artificially, by means of intramuscular injections with Human Gonadotrophin Corionic (HCG). The males had not been induced for the easiness on the release of the milt. After the application of the treatments the animals were kept until four mounts of age moment in which, was proven the effectiness of the treatments by the counting of the number of chromosomes in mitotic preparations in vivo of kidney cells and culture in vitro of limphocytes. Significant differences in the times of duration of the shoks for the two assays had been found, in relation to the estimate of the survival taxes which had been inversely dependents on the temperature. The result of the analysis of the counting of chromosomes in all treatments, showed a normal diploid modal number (2n: 44), indicanting that the not attainment of tetraploids tilapias must be probably due to the animals on which the tests were made
49
Carrillo, Maurício. "Indução à tetraploidia em tilápia nilótica Oreochromis niloticus utilizando-se choque térmico /." Jaboticabal, 2004. http://hdl.handle.net/11449/144121.
Full textAbstract:
Orientadora: Elizabeth Romagosa<br>Banca: Pedro Manoel Galetti<br>Banca: Teresa Cristina Ribeiro Dias Koberstein<br>Resumo: A indução à tetraploidia em tilápia do Nilo foi realizada mediante a aplicação de choques térmicos quentes a uma temperatura de 41º C, utilizando-se três tempos pós-fertilização (P.F.). No 1º ensaio, utilizaram-se tempos de P.F. de 50, 55 e 60 minutos e duração de 2 e de 5 minutos e no 2º de 24, 27 e 30 minutos, com duração de 5 e de 8 minutos. Para a coleta dos gametas, somente as fêmeas que apresentaram características secundárias de maturação foram induzidas artificialmente, por meio de injeções intramusculares com Gonadotrofina Coriônica Humana (HCG). Os machos não foram induzidos pela facilidade na liberação do sêmen. Depois da aplicação dos tratamentos os animais foram mantidos ate os quatro meses de idade momento no qual, foi comprovada a eficácia dos tratamentos mediante a contagem do número de cromossomos em preparações mitóticas 'in vivo" de células de rim e a cultura "in vitro" de linfócitos. Foram encontradas diferenças significativas (P< 0.05) nos tempos de duração do choque para os dois ensaios, em relação à estimativa das taxas de sobrevivência as quais foram inversamente dependentes da temperatura. O resultado das análises da contagem de cromossomos em todos os tratamentos, mostrou um número modal normal diplóide (2n=44), indicando que a não obtenção de tilápias tetraploides deva-se provavelmente à idade dos animais em que foi feita as provas<br>Abstract: The induction of the tetraploid in Nile tilapia was carried through means of application of hot thermal shoks to a temperature of 41,0 ºC, using it three times after-fertilization (A.F.). On the 1º assay A.P., times of 50, 55 and 60 minutes have been used and duration of 2 and 5 minutes and on the 2º of 24,27 and 30 minutes, with duration of 5 and 8 minutes. For the collection of gametes, the females that preented secondary characteristics of maduration had only been induced artificially, by means of intramuscular injections with Human Gonadotrophin Corionic (HCG). The males had not been induced for the easiness on the release of the milt. After the application of the treatments the animals were kept until four mounts of age moment in which, was proven the effectiness of the treatments by the counting of the number of chromosomes in mitotic preparations " in vivo" of kidney cells and culture "in vitro" of limphocytes. Significant differences in the times of duration of the shoks for the two assays had been found, in relation to the estimate of the survival taxes which had been inversely dependents on the temperature. The result of the analysis of the counting of chromosomes in all treatments, showed a normal diploid modal number (2n: 44), indicanting that the not attainment of tetraploids tilapias must be probably due to the animals on which the tests were made<br>Mestre
50
Bai, Jian. "Actin reduction by MsrB2 is a key component of the cytokinetic abscission checkpoint and prevents tetraploidy." Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS041.pdf.
Full textAbstract:
La dernière étape de la cytocinèse, appelée abscission, conduit à la séparation physique des deux cellules filles issues de la division cellulaire. En réponse à la présence anormale de chromatine dans le pont intercellulaire, un point de contrôle conservé au court de l’évolution appelé « abscission / NoCut checkpoint » retarde l’abscission et évite la formation de cellules binucléées en stabilisant le pont intercellulaire. Comment l’activation de ce point de contrôle permet de maintenir le pont intercellulaire pendant plusieurs heures reste mal connu mais pourrait reposer sur la présence de filaments d’actine. Ce travail de thèse a permis de montrer que la polymérisation de l’actine-F est essentielle pour la stabilisation du pont intercellulaire dans les cellules humaines, uniquement en cas de présence anormale de chromatine. En explorant le mécanisme sous-jacent, nous avons découvert que la réductase humaine MsrB2 (Methionine sulfoxide reductase B2) localisée dans le cytosol est fortement recrutée au midbody spécifiquement en cas de présence anormale de chromatine, où elle promeut la polymérisation d’actine-F. Dans les cellules ayant une expression réduite de MsrB2, les niveaux d’actine-F dans le pont sont diminués et la présence anormale de chromatine aboutit à la formation de cellules binucléées du fait de l’instabilité des ponts intercellulaires. De plus, nous avons démontré que MsrB2 réduit de manière sélective les monomères d’actine oxydés et ainsi, contrebalance l’activité de MICAL1, une enzyme connue pour dépolymériser l’actine-F en oxydant directement les filaments d’actine. Ce travail révèle ainsi que la réduction des monomères d’actine par MsrB2 est un composant clé du « NoCut checkpoint » puisqu’elle favorise la polymérisation des filaments d’actine et empêche la formation de cellules tétraploïdes, un des éléments déclencheurs de la tumorigenèse. Il s’agit de la première implication d’une réaction de réduction dans la division cellulaire<br>Abscission is the terminal step of cytokinesis leading to the physical separation of the daughter cells. In response to the abnormal presence of lagging chromatin between dividing cells, an evolutionarily-conserved abscission/NoCut checkpoint delays abscission and prevents formation of binucleated cells by stabilizing the cytokinetic intercellular bridge. How this bridge is stably maintained for hours while the checkpoint is activated is poorly understood and has been proposed to rely on F-actin in the bridge region. This thesis work revealed that actin polymerization is essential for stabilizing the cytokinetic bridge in human cells, exclusively when lagging chromatin is present. Mechanistically, we found that a cytosolic pool of human Methionine sulfoxide reductase B2 (MsrB2) is strongly recruited at the midbody specifically in the presence of lagging chromatin, where it promotes actin polymerization. In MsrB2-depleted cells, F-actin levels are decreased and dividing cells with lagging chromatin become binucleated as a consequence of unstable bridges. We further demonstrated that MsrB2 selectively reduces oxidized actin monomers and thereby counteracts MICAL1, an enzyme known to depolymerize actin filaments by direct oxidation. This work thus reveals that actin reduction by MsrB2 is a key component of the abscission checkpoint that favors F-actin polymerization and limits tetraploidy, a starting point for tumorigenesis. This work demonstrates the first implication of a protein reduction reaction in cell division