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Puzey, Joshua Robert. "Plant MicroRNA Evolution and Mechanisms of Shape Change in Plants." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10143.
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Plant microRNAs have been shown to have important roles in regulating diverse processes ranging from reproductive development to stress response. In the first two chapters, I focus on miRNA diversity in Aquilegia studying both anciently evolved broadly conserved and rapidly evolving species specific miRNAs. In chapter one, I utilize Aquilegia's critical phylogenetic position between the well developed models Arabidopsis thaliana and Oryza sativa to study the evolution of ancient miRNAs across the angiosperms. In chapter two, I utilize smallRNA high-throughput sequencing to annotate Aquilegia specific miRNAs and, in the process, uncover the novel regulation of a floral homeotic gene by an Aquilegia-specific miRNA. In chapter three, I look at the tissue specific development of miRNA regulation in the bioenergetically relevant model organism Populus trichocarpa. High-throughput smallRNA sequencing from four diverse tissue sets including leaves, xylem, mechanically treated xylem, and pooled vegetative and reproductive tissues were analyzed, revealing a total of 155 previously unannotated miRNAs, most of which are P. trichocarpa specific. Expanding on my work with the petal identity pathway, I turned a broader analysis of Aquilegia petal spurs. Petal spurs are the distinguishing characteristic of Aquilegia and are argued to be a key innovation in the adaptive radiation of the genus. In the fourth chapter, I explore the cellular basis of extreme spur length diversity in the genus and find that a single parameter, cell shape, can explain this morphological range. Next, I seek to describe the cellular patterns that give rise to a spur primoridia from an initially flat laminar petal and find that spur initiation is characterized by concentrated, prolonged, and oriented cell divisions. Inspired by this quantitative analysis of growth, chapter five looks at the mechanisms of shape change in cucumber tendrils. I find that anisotropic contraction of a multi-layered gelatinous fiber ribbon explains coiling in cucumbers. Surprisingly, we discover that tendrils display twistless-overwinding when pulled and exhibit an unforeseen force-extension response as a result. These results provide the design basis for twistless springs with tunable mechanical responses and serve as a clear example of how the biological systems can inspire applied mechanical designs.
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van, Zyl Albertha R. "Development of plant-produced Bluetongue virus vaccines." Doctoral thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/28248.
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Bluetongue is a disease of domestic and wild ruminants caused by Bluetongue virus (BTV). It has caused several serious outbreaks, the most recent occurring in Northern Europe in 2006 during which high mortality rates of livestock were reported. The only vaccines currently approved and commercially available for use are live-attenuated or inactivated virus strains and although these are effective, there is the risk of reversion in the case of live-attenuated strains to more virulent forms by recombination. Another drawback associated with the use of live-attenuated virus vaccines is that they are not DIVA (differentiate infected from vaccinated animals) compliant, this means that naturally infected animals cannot be distinguished from vaccinated animals. Recombinantly produced vaccines would be preferable to minimize the risks associated with live-attenuated virus vaccines and also enable the development of candidate vaccines that are DIVA-compliant. A number of recombinant vaccine candidates have been developed against BTV, with the most promising vaccine consisting of BTV virus-like particles (VLPs). BTV VLPs were successfully produced in insect cells by the co-expression of the four BTV capsid proteins (VP2, VP3, VP5 and VP7). Sheep vaccinated with insect cell-produced BTV VLPs were shown to be protected against challenge with wild type virus. However, the high costs associated with the production and scale-up of BTV VLPs in insect cells has possibly limited their widespread application. Plants – such as N. benthamiana – provides a safe, efficient and cost effective system for the production of recombinant proteins. In this study the best plant expression vector with which to co-express the four BTV serotype 8 (BTV-8) VPs – which direct formation of BTV-8 VLPs – was identified. Expression and purification of the BTV-8 VLPs was optimised with the aim of producing a VLP-based vaccine for BTV-8. It was further undertaken to develop two novel second generation plant-produced protein body (PB) vaccines that are DIVA compliant. Mice were immunised with the plantproduced VLP and PB vaccines in order to analyse their ability to elicit humoral immune responses.
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Dennis, Susan Jennifer. "Development of plant-produced African horse sickness vaccines." Thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/33687.
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African horse sickness is a devastating disease that causes great suffering and many fatalities amongst horses in sub-Saharan Africa. It is caused by nine different serotypes of the orbivirus African horse sickness virus (AHSV) and it is spread by Culicoid midges. The disease has significant economic consequences for the equine industry both in southern Africa and increasingly further afield as the geographic distribution of the midge vector broadens with global warming and climate change. Live attenuated vaccines (LAV) have been used with relative success for many decades, but carry the risk of reversion to virulence and/or genetic re-assortment between outbreak and vaccine strains. Furthermore, the vaccines lack DIVA capacity, the ability to distinguish between vaccine-induced immunity and that induced by natural infection. These concerns have motivated interest in the development of new, more favourable recombinant vaccines, initially focusing on the use of insect and mammalian cell expression systems. More recently, several studies have demonstrated the potential for using plant expression systems for the production of virus-like particles (VLPs), which are excellent vaccine candidates, as they do not contain virus genetic material and are DIVA compliant. A vaccine alternative to the currently used live vaccine necessarily needs to provide protection against all nine serotypes of the virus. Cross-protection has been shown to exist between certain serotypes of the virus and as capsid protein VP2 is the protein responsible for AHSV serotype specificity, the idea of a plant-produced VLP vaccine containing a representative VP2 protein from each of the different serotype groups, was conceived. Such a vaccine would potentially provideprotection against all 9 serotypes of the virus and would have DIVA capability. Furthermore, it would address local concerns regarding the use of a live vaccine and would serve as a potentially acceptable prophylactic or rapid response antidote in the wider international context. This work describes two approaches in the development of VLP vaccines in plants. In the first part of this study, the ability of 2 different serotypes of plant-produced AHSV VLPs to safely stimulate an immune response in horses, was investigated. Co-infiltration of Nicotiana benthamiana plants with Agrobacterium constructs encoding the four AHSV serotype 5 structural proteins VP2, VP3, VP5 and VP7, was shown to result in assembly of complete VLPs. Furthermore, co-infiltration with the constructs, encoding VP3 and VP7, together with constructs encoding the two outer capsid proteins VP2 and VP5 of a second serotype, AHSV 4, resulted in assembly of complete AHSV 4 VLPs. Horses vaccinated with plant-produced AHSV 4 and 5 VLPs, all seroconverted after two doses of the vaccine and the virus neutralization titres indicated that the plant-produced VLP vaccines are likely to be at least as effective as the current LAV in protecting against AHSV 4 or AHSV 5. However, they have the added advantage of being free from any of the associated risks of a live vaccine, such as reversion to virulence or genetic re-assortment with field or vaccine strains. In the second part of the study, the use of the so-called SpyTag/SpyCatcher or bacterial “superglue” technology was investigated. This technology is based on the peptide SpyTag irreversibly coupling to the SpyCatcher protein, forming an isopeptide bond when the two are mixed together. The plant-based expression system was used to produce Spy VLPs consisting of either Acinetobacter phage (AP205) VLPs or tobacco mosaic virus (TMV) VLPs displaying a SpyTag or SpyCatcher peptide. In addition, AHSV 5 VP2 displaying SpyTag was expressed in plants and several coupling strategies were tested to determine whether AP205 particles displaying AHSV 5 VP2 could be formed as a result of binding between the SpyTag/SpyCatcher moieties of the recombinant proteins. Although it was not proven that coupling occurred, this research will pave the way towards developing a multivalent vaccine platform whereby VP2 of different AHSV serotypes can be displayed on the Spy VLP surface to allow optimal presentation of these proteins to the animal's immune system. Together, the results obtained in this study show that there is great potential for the production of novel, diverse, efficacious and economically viable AHSV VLP vaccines in plants.
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Anna, Newman-Griffis Hare. "Plant nuclear envelope-associated proteins function in development and symbiosis." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1542733901078983.
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Catarino, Bruno. "Evolution of bHLH transcription factors that control epidermal cell development in plants." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:88f764a3-dfe9-432f-a33a-3db3981c21d9.
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The colonization of the arid continental surface by plants was one of the milestones in Earth's history. Morphological innovations, such as the origin of complex 3D tissues, allowed the successful colonization and radiation of plants on land. The epidermis is the outermost plant tissue that constitutes the interface between the plant and the environment. Thus, the evolution of epidermal cells was crucial for the adaptation of plants on the terrestrial arid environment. I undertook a combined approach that aims to understand the evolutionary trends that drove land plant colonization and the genetic mechanisms that underlie the development of the epidermis. This approach includes: 1) analyses of plant transcription factors (TFs) families distribution and diversification, with a particular focus on the basic Helix-Loop-Helix (bHLH) TF family, and 2) functional characterization of a putatively conserved bHLH TF subfamily involved in epidermal cell development in land plants. Here, I showed that there was a stepwise increase in the number of transcription factor (TF) families and bHLH subfamilies that predated the colonization of the terrestrial surface by plants. The subsequent increase in TF number on land was through duplication within pre-existing TF families and subfamilies. Moreover, a similar trend occurred in metazoan bHLH TF, suggesting that the majority of innovation in plant and metazoan TF families occurred in the Precambrian before the Phanerozoic radiation of land plants and metazoans. Furthermore, I demonstrated that the function of IIIf bHLH TFs in controlling the development of the epidermal cell layer is conserved between liverworts and angiosperms. This suggests that IIIf bHLH TFs are ancient and conserved regulators of epidermal cell development since the early colonization of the land by plants. Moreover, these bHLH TFs were recruited during the evolution of land plants to control the development of seemingly unrelated morphological characters in specific lineages of extant land plants. The recruitment of ancient developmental regulators to control distinct and unrelated developmental processes in land plants might underlie the huge morphological and taxonomic radiation of plants on land.
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Cao, Jingyi. "CELL TYPE-SPECIFIC ALTERNATIVE POLYADENYLATION IN ARABIDOPSIS DURING DEVELOPMENT AND STRESS RESPONSE." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1492702815819455.
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Hable, Whitney Elizabeth 1967. "Expression and regulation of phytoene desaturase during maize seed development." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282172.
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An essential component of development is the accumulation of specific metabolites in a temporal and tissue-specific manner. The growth regulator abscisic acid (ABA), which accumulates at a specific time during seed development, is required for seed maturation and prevents the premature developmental switch from dormancy to germination ABA accumulates differently in two tissues of the seed; levels in the embryo are several-fold higher than in the endosperm and the temporal accumulation of ABA is also different between these tissues. To begin to understand how ABA accumulation is regulated during seed development, the regulation of ABA biosynthesis was investigated. The approach taken was to examine the expression of the biosynthetic enzyme, phytoene desaturase (PDS), which catalyzes a regulated step in ABA synthesis in several other organisms (Bramley, 1985, Sandmann et al., 1989, Hugueney et al., 1992 and Giuliano et al., 1993). Unlike ABA accumulation, PDS transcript and protein levels were higher in the endosperm than in the embryo. The spatial difference in PDS levels did correlate with levels of the pathway intermediate, beta-carotene, suggesting that PDS may control the synthesis of ABA precursors while subsequent enzymes may regulate ABA accumulation. The temporal expression of Pds was also unrelated to ABA accumulation. In the endosperm, transcript levels were initially high and declined during desiccation while protein levels remained high throughout development. In the embryo, transcript levels were low and constant while protein levels declined. There are several maize mutants (viviparous mutants) disrupted in ABA biosynthesis, resulting in decreased levels of ABA and premature germination. Analysis of the Pds allele and transcript in the viviparous-5 mutant showed that the gene contains multiple insertions and deletions, giving rise to a larger transcript. In addition, the 55 kDa PDS protein was not detected in the vp5 mutant by immunoblot analysis, indicating that the vp5 phenotype results from a mutation at the PDS locus. To determine whether the wild type protein encoded by the ABA mutant, vp2, or the pathway intermediate, lycopene, regulate PDS, transcript and protein levels were compared in wild type and mutant (vp2 and vp7, respectively) seeds. The levels of PDS were not significantly different in vp2 or vp7 wild type and mutant seeds, suggesting that neither the VP2 protein nor lycopene regulate PDS at the steady-state transcript or protein level.
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Landberg, Katarina. "TERMINAL FLOWER2, the Arabidopsis HETEROCHROMATIN PROTEIN1 Homolog, and its Involvement in Plant Development." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7502.
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Zhang, Chang. "Abscisic Acid And Nitrate Transporter Mtlatd/nip Signaling In Root And Nodule Development In Medicago Truncatula." ScholarWorks @ UVM, 2015. http://scholarworks.uvm.edu/graddis/380.
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Abscisic acid (ABA) is a plant hormone that regulates various developmental processes and environmental stress responses. ABA modulates growth of both primary roots and lateral roots, helping to shape root architecture. The lateral root organ defective (latd) mutants, disrupted in the MtLATD/NIP gene, encoding a nitrate transporter, have severe root growth defects that can be rescued by applying ABA. However, the way in which ABA stimulates latd root growth is unclear, and the downstream components of MtLATD/NIP and ABA signaling are completely unknown. To answer these questions, this dissertation focuses on two major potential downstream regulators: Reactive Oxygen Species (ROS) and transcription factors (TFs).
ROS are important signaling molecules required in ABA-induced stomatal closure under drought or osmotic stresses, but their role in ABA regulation of root development is unclear. I found that latd mutant roots have increased ROS levels, and the expression level of several MtRboh genes, which encode major ROS-producing enzymes, the NADPH oxidases, is also increased. ABA decreases the amount of ROS in latd roots and also reduces expression of MtRbohC, in particular. In addition, I observed that latd mutant roots have cell elongation defects, which can also be rescued by exogenous ABA. I demonstrated that pharmaceutically decreasing ROS levels using an NADPH oxidase inhibitor, or reducing the expression of MtRbohC using RNA interference can increase cell elongation and stimulate lateral root elongation in latd roots. These findings have revealed a mechanism by which ABA restores root growth in latd mutant roots via regulating ROS levels, and identified MtRbohC as an important downstream target of ABA signaling mediated by MtLATD/NIP.
TFs act as regulatory nodes controlling the transcription of gene clusters and playing a crucial role in plant growth and development. Using a high-throughput TF profiling approach, I have identified 20 TFs that exhibit altered expression levels in latd mutant roots as compared to wild type, 60% of which can be restored to normal levels by ABA. My analysis also revealed that ABA regulates the expression of a different set of TFs in latd roots, suggesting that MtLATD/NIP is crucial for ABA regulation of TF expression. Moreover, ABA changes the TFs regulated by MtLATD/NIP almost completely, indicating a tight control of ABA on TFs regulated by MtLATD/NIP. Surprisingly, I found that the expression of NODULATION SIGNALING PATHWAY 2 (MtNSP2), a GRAS family TF required for nodulation, is regulated by MtLATD/NIP, ABA and nitrate in non-symbiotic roots. In symbiotic roots, MtLATD/NIP is required for the transcriptional signaling pathway downstream of MtNSP2 in the epidermis as well as induction of MtNSP2 expression by cytokinin and subsequent activation of its downstream targets in the cortex. These findings indicate that MtLATD/NIP functions in nodulation signal transduction upstream of MtNSP2, and mediates crosstalk with cytokinin.
Together, these two approaches have begun to characterize a signaling pathway downstream of ABA and MtLATD/NIP that involves ROS, MtNSP2, and a core group of TFs in the regulation of root development and nodulation in M. truncatula.
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Logsdon, Charles A. "Mutants of Arabidopsis thaliana exhibiting abnormal gravitropism and seedling plastid development." [Bloomington, Ind.] : Indiana University, 2005. http://wwwlib.umi.com/dissertations/fullcit/3162266.
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Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2005.Title from PDF t.p. (viewed Dec. 2, 2008). Source: Dissertation Abstracts International, Volume: 66-01, Section: B, page: 0146. Chair: Roger P. Hangarter.
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Rieger, Mary Alice. "Horticultural management and population biology of several Banksia species." Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09phr554.pdf.
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Bibliography: leaves 159-205. This research aims to improve understanding of the control of flowering in relation to photoperiod and temperature to increase knowledge of the floral initiation trigger for Banksia. An exploration of the population biology in relation to genetic variation present in commercial and natural populations of Banksia will provide information on the gene pool for breeding programs. Molecular biology techniques have been used to explore areas such as pollen competition and gene flow.
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Workman, Rachael Elizabeth. "Effects of Arbuscular Mycorrhizal Fungal Infection and Common Mycelial Network Formation on Invasive Plant Competition." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/2025.
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Understanding the biotic factors influencing invasive plant performance is essential for managing invaded land and preventing further exotic establishment and spread. I studied how competition between both conspecifics and native co-habitants and arbuscular mycorrhizal fungal (AMF) impacted the success of the invasive bunchgrass Brachypodium sylvaticumin early growth stages. I examined whether invasive plants performed and competed differently when grown in soil containing AMF from adjacent invaded and noninvaded ranges in order to determine the contribution of AMF to both monoculture stability and spread of the invasive to noninvaded territory. I also directly manipulated common mycelial network (CMN) formation by AMF to determine hyphal network contribution to competitive interactions.
I found that invasive plants performed most poorly (as indicated by decreased chlorophyll content, size and shoot dry mass) in invaded range soil against conspecifics. This could be two-pronged evidence for existing biotic pressure on the invasives to expand into adjacent noninvaded ranges. I also found a negative effect of AMF colonization and invasive plant performance, potentially indicating deleterious plant-soil feedbacks which could help maintain plant biodiversity at a community level. CMN effects were found to be interactive with root competition and directly affected the performance and nutrient status of B. sylvaticum. Although no direct correlations between AMF colonization levels and competition were found, CMN presence contributed significantly to plant growth and nutrient status. Therefore AMF, through infection and CMN formation, may be able to influence invasive plant growth and spread in the field.
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Xu, Limin. "Development of molecular approaches in the study of lettuce downy mildew (Bremia lactucae) population biology." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/49561/.
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Downy mildew of lettuce caused by Bremia lactucae is a serious disease resulting in yield loss. The population structure of the pathogen in the UK is poorly understood. This PhD project concentrated on developing molecular markers to differentiate the genotypic variation of B. lactucae populations, with the aim of improving methods to investigate lettuce - Bremia interactions. Thirty-seven B. lactucae isolates (including single-spore and new field isolates) were collected and characterized for virulence using the conventional International Bremia Evaluation Board (IBEB) differential set. Microsatellite markers (SSR, ISSR) were investigated for Bremia race specific marker development. Three isolates of B. lactucae were characterized by ISSR (inter simple sequence repeat) primers, although the polymorphic DNA could not be cloned in this project due to the highly variable results of the ISSR process. Some microsatellite repeats were found in B. lactucae isolates sequences that amplified by Plasmopara viticola (grape downy mildew) SSR markers. The development of Simple Sequence Repeat (SSR) markers from Bremia genomic DNA was not successful, which might result from the primers used being unsuitable for Bremia microsatellite enrichment. Bremia specific ITS primers were used for quantitative PCR. RxLR primers obtained from UC Davis (USA) were tested using the collection of B. lactucae isolates. RxLR1 primers distinguished between isolates BL801 and BL806. Eight SNPs were identified in three isolates amplified by RxLR5. No polymorphism was observed on the gel for the remaining RxLR primers on single spore races. Unrefined field isolates showed more polymorphisms on the gel than single spore isolates. The phenotypic differences between these two isolates have been identified by the IBEB differential set. Microscopy and qPCR quantification were used to investigate the compatible and incompatible interactions. The results suggest that BL801 is more virulent than BL806, as more infection structures were observed in IBEB resistant cultivars. Results of qPCR and spore count/unit weight of cotyledons showed that BL801 and BL806 were significantly different. The qPCR quantification results from 4 and 5 dpi were correlated with the spore count/unit weight of cotyledons. Although further work is required to develop race specific markers, the methods used in this project demonstrate the potential use of molecular markers to investigate lettuce - Bremia interactions.
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Blancaflor, Elison B., Aruna Kilaru, Jantana Keereetaweep, Bibi Rafeiza Khan, Lionel Faure, and Kent D. Chapman. "N-Acylethanolamines: Lipid Metabolites with Functions in Plant Growth and Development." Digital Commons @ East Tennessee State University, 2014. https://doi.org/10.1111/tpj.12427.
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Twenty years ago, N‐acylethanolamines (NAEs) were considered by many lipid chemists to be biological ‘artifacts’ of tissue damage, and were, at best, thought to be minor lipohilic constituents of various organisms. However, that changed dramatically in 1993, when anandamide, an NAE of arachidonic acid (N‐arachidonylethanolamine), was shown to bind to the human cannabinoid receptor (CB1) and activate intracellular signal cascades in mammalian neurons. Now NAEs of various types have been identified in diverse multicellular organisms, in which they display profound biological effects. Although targets of NAEs are still being uncovered, and probably vary among eukaryotic species, there appears to be remarkable conservation of the machinery that metabolizes these bioactive fatty acid conjugates of ethanolamine. This review focuses on the metabolism and functions of NAEs in higher plants, with specific reference to the formation, hydrolysis and oxidation of these potent lipid mediators. The discussion centers mostly on early seedling growth and development, for which NAE metabolism has received the most attention, but also considers other areas of plant development in which NAE metabolism has been implicated. Where appropriate, we indicate cross‐kingdom conservation in NAE metabolic pathways and metabolites, and suggest areas where opportunities for further investigation appear most pressing.
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Douglas, Stephanie. "The development of molecular markers for use across all plant species using expressed sequence tags." FIU Digital Commons, 2006. http://digitalcommons.fiu.edu/etd/3234.
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There are over a half a million plant species on earth, and we use them in virtually every aspect of our lives. Little or no genomic information exists about the vast majority of these plants. This study investigated the use of Expressed Sequence Tags (ESTs) to locate highly conserved sequences from which to design a set of universal molecular markers for all plant species. Plant species for this study were chosen to representative of the plant kingdom. This was done by sampling several individuals of at least one species from all of the major terrestrial plant groups.
Conserved sequences are generally found in a wide range of plants species and often in all plant species. A set of eight degenerate primers was designed specifically to detect Single Nucleotide Polymorphisms (SNPs) using capillary array electrophoresis-single stranded conformational polymorphism (CAE-SSCP). The results of this research confirmed that homologous regions of the genome could be used to design universal molecular markers for all plant species.
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Murphy, Phillip James. "Plant-fungal interactions during vesicular-arbuscular mycorrhiza development : a molecular approach." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phm9778.pdf.
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Bibliography: leaves 153-185. Vesicular-arbuscular (VA) mycorrhiza formation is a complex process which is under the genetic control of both plant and fungus. This project aims to develop a model infection system in Hordeum vulgare L. (barley) suitable for molecular analysis; to identify host plant genes differentially expressed during the early stages of the infection process; and to screen a mutant barley population for phenotypes which form abnormal mycorrhizas.
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Wehmeyer, Nadja. "Arabidopsis class I small heat shock proteins: Regulation and functional analysis during seed development." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284011.
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The goal of this dissertation was to analyze the regulation and function of cytoplasmic class I small heat shock proteins (sHSPs) during seed development in Arabidopsis thaliana. Results show that two class I sHSPs accumulate in late seed maturation, persist in the dry seed and decline rapidly during germination. HSP17.4 accounts for 90% of total class I sHSP in the dry seed. The temporal pattern of sHSP accumulation during seed development suggests that HSP17.4 may help establish seed properties that are acquired during late seed maturation, such as dormancy or desiccation tolerance. Several mutants with reduced seed dormancy were determined to accumulate wild type levels of HSP17.4, however, all desiccation intolerant seeds analyzed had decreased levels of HSP17.4. Thus, HSP17.4 reduction correlates with desiccation intolerance. In total, these data suggest that HSP17.4 is not sufficient for seed dormancy and that it may be necessary for desiccation tolerance. The localization and regulation of HSP17.4 were examined in developing Arabidopsis seeds by transforming plants with hsp17.4 promoter fused to the β-glucuronidase (GUS) gene. HSP17.4::GUS expression was detected in the cotyledons early in seed development and eventually throughout the embryo. Arabidopsis embryos showed a much different pattern of HSP17.4::GUS expression in response to heat indicating distinct mechanisms regulate sHSP transcription during heat shock and during development. To analyze seed specific transcriptional activator regulation of HSP17.4 transcription, HSP17.4::GUS transgenic plants were crossed to seed transcriptional activator mutants. Results showed aberrant localization of HSP17.4::GUS in fus3-3 and lec1-2 seeds and negligible levels in abi3-6. These results strongly implicate AB13 in the transcriptional regulation of HSP17.4. To analyze more specifically HSP17.4 function, transgenic antisense technology was used to suppress hsp17.4 expression to 30--50% of wild type. These lines exhibited a reduced dormancy phenotype as assayed by reduced sensitivity to germination on ABA and by the ability of fresh seed to germinate. These data provide insight into the localization, regulation and function of HSP17.4 during seed maturation. The seed-specific transcriptional activator ABI3 is implicated in controlling hsp17.4 expression during development. Overall, these results demonstrate the importance of HSP17.4 during seed maturation, and establish a role for sHSPs in dormancy.
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Ajayi, Oyeyemi Olugbenga. "Three Beta-Glucuronosyltransferase Genes Involved in Arabinogalactan-Protein Biosynthesis and Their Roles in Growth and Development of Arabidopsis." Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1625497309408518.
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Ajayi, Oyeyemi Olugbenga. "Three Beta-Glucuronosyltransferase Genes Involved in Arabinogalactan-Protein Biosynthesis and Their Roles in Growth and Development of Arabidopsis." Ohio University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1625497309408518.
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Paddock, Troy N. "Genetic manipulation of NADPH: Protochlorophyllide Oxidoreductase content in Arabidopsis reveals essential roles in prolamellar body formation and plant development." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1211899658.
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Zajac, Mark Arthur. "Population development of Philaenus spumarius (Linnaeus) (Homoptera: Cercopidae) on strawberry, and plant responses to spittlebug feeding /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487588249822402.
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Patel, Jigarkumar J. "The Role of Polyamine Uptake Transporters on Growth and Development of Arabidopsis Thaliana." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1429280174.
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Wang, Hao-Ching. "Role of tobacco anionic peroxidase on plant growth and development and the effect on endogenous auxin production /." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu148639447597754.
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Heath, Jeremy J. "Assessing the drivers of adaptive radiation in a complex of gall midges: A multitrophic perspective on ecological speciation." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1364555299.
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Wright, Bethany Ann. "Systematic studies in the genus Phlox (polemoniaceae): cytotypic variation in Phlox nana nutt. and utility of a low copy nuclear gene region (IDHB) for phylogeny development." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18242.
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Master of ScienceDepartment of Biology
Carolyn J. Ferguson
The genus Phlox L. presents intriguing opportunities for systematics research, and P. nana is of particular interest. Phlox nana occurs chiefly in mountains of the Chihuahuan desert to northern New Mexico, and it exhibits much morphological variation across its range. Historically, this taxon has been recognized as a single species (sometimes with infraspecific taxa), or as several species. Perhaps most interesting, variation in ploidy level (cytotypic variation) has been evidenced for P. nana. This research employed flow cytometry methods in conjunction with chromosome counts to document patterns of cytotypic variation. Intensive fieldwork in Arizona, New Mexico and Texas enabled excellent sampling, and evaluation of ploidy level for 76 populations was achieved. Diploid and tetraploid chromosome counts were made (four diploid counts; five tetraploid counts), and flow cytometry was conducted on all populations, providing evidence for diploid, tetraploid and hexaploid populations. Polyploids were found to occur in many geographical areas, and in some regions, diploids and polyploids occur in close geographical proximity (e.g., within both the Davis Mountains and the Chisos Mountains of west Texas). Genome size data are presented (with discussion of unusual populations), and geographic patterns of cytotypic variation are presented and discussed. Patterns are also briefly considered with respect to morphology and taxonomy: cytotypic variation does not readily align with historical recognition of taxonomic variation, and this work sets the stage for ongoing, detailed morphometric study. Research on particular species of Phlox benefits from an understanding of a broad phylogenetic context, and low copy nuclear DNA regions are an important resource for phylogeny development. This research further evaluated part of the NADP-dependent isocitrate dehydrogenase gene (idhB) for its usefulness in inferring relationships in Phlox. Samples were PCR amplified for idhB and cloned, and resulting sequences were added to a larger set of idhB sequence data previously developed in the lab. A total of 163 samples were included, and Bayesian Inference and Maximum Parsimony analyses were conducted for complete data sets. Phylogenetic findings are discussed in light of previous work based on chloroplast and high copy nuclear DNA regions, and challenges and utility of using idhB are discussed.
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Blackman, Benjamin K. "Evolutionary genetics of flowering time regulation and variation in Helianthus." [Bloomington, Ind.] : Indiana University, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3373495.
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Thesis (Ph.D.)--Indiana University, Dept. of Biology 2009.Title from home page (viewed on Jul 8, 2010). Source: Dissertation Abstracts International, Volume: 70-10, Section: B, page: 5957. Advisers: Loren H. Rieseberg; Scott D. Michaels.
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Svensson, Mats. "Evolution of a family of plant genes with regulatory functions in development; studies on Picea abies and Lycopodium annotinum." Doctoral thesis, Uppsala universitet, Institutionen för evolutionsbiologi, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-1194.
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This work is focused on the molecular genetic basis for morphological change in evolution. Genes belonging to the MADS-box gene family, which includes members, that determine angiosperm floral organ identity, were isolated and characterised from two non-angiosperm plants; Norway spruce (Picea abies) and the club moss (Lycopodium annotinum). The exon/intron organisation of the isolated genes was determined, and its significance as an independent test of the position of a gene within the gene family tree evaluatad. identity genes were identified. One Norway spruce gene, DAL2, is an ortholog to Norway spruce genes that are closely related to the angiosperm floral organ angiosperm C-class MADS-box genes that specify stamen and carpel identity. The expression of DAL2 in male and female cones suggests that orthologous genes in conifers and argiosperms determine the identities of pollen- and seed-bearing structures. Constitutive expression of DAL2 in the angiosperm Arabidopsis resulted in homeotic conversions very similar to those resulting from constiutive expression of the Arabidopsis C-class gene. Angiosperm B-class MADS-box genes determine petal and stamen identity. The isolated Norway spruce B-class orthologs: DAL11, DAL12, and DAL13 are expressed in the developing male cones exclusively, suggesting a conserved function of B-class related genes in the determination of pollen forming organs among seed plants. No orthologs to the floral organ identity genes couId be isolated from the club moss, suggesting that the origin of these gene classes may be coupled to the origin of the pollen and the seed. The club moss MADS-box genes, LAMB2, LAMB4 and LAMB6, conform structurally to plant type MADS-box genes, whereas LAMB1 is divergent in details. The genes LAMB3 and LAMB5 encode shorter proteins. LAMB1 expression is restricted to reproductive structures, whereas LAMB2, LAMB4, LAMB5 and LAMB6 are broadly expressed. The implications from these expression patterns on the ancestral function of plant type MADS-box genes are discussed.
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Marty, DeeMarie. "Characterization of Lab and Novel Agrobacterium Species for Development of New Tools for Plant Transformations." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1406138595.
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Calixte, Sophie. "RNA processing of the ccmFn-rps1 and rpl5-Psirps14-cox3 loci in wheat mitochondria during seedling development." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27580.
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Plant mitochondria possess a gene expression system in which post-transcriptional events, such as transcript end maturation and turnover mechanisms play a key role in regulating the transcriptome. In addition, during early developmental stages of embryo germination, differing transcript profiles have been seen. This research focuses on two loci in wheat mitochondria, ccmFn-rps1 and rpl5-Psirps14-cox3, to elucidate the transcription and post-transcriptional events involved in their expression. Northern analysis of the ccmFN-rps1 genes during early seed-to-seedling development reveals a 3.2 kb primary transcript and a 2.7 kb bicistronic mRNA. A 0.7 kb monocistronic rps1 mRNA is detectable up to 2d but there is no detectable monocistronic ccmFN transcript during the stages examined. Transcript ends were mapped using circular-RT-PCR and phosphatase treatment at three different developmental stages and revealed two processing sites as well as a single 3' end common to all three transcripts. The 5' ends of the processed rps1 transcripts are heterogeneous and do not always include the start codon, questioning the rps1 transcript functionality.
Gene order varies between plant species due to the high recombination rate in mitochondrial genomes, as is seen for rpl5-Psirps14 in wheat and rice. In both plants, the functional rps14 gene is encoded in the nucleus and the mitochondrial rps14 copy is a pseudogene. In wheat, rpl5-Psirps14 are co-transcribed with cox3 as two RNA species of 3.5 kb and 2.7 kb at 24hr post-imbibition and exhibit developmentally-specific differences in abundance in seedlings. Two promoter regions were mapped in wheat upstream of rpl5 and both transcripts have the same 3' end. In rice 24hr and 6d however, rpl5-Psirps14 are co-transcribed as a 1.4 kb bicistronic mRNA. This presumably reflects the different regulatory signals used in different species. In addition, rpl5 has been subject to several independent gene transfers to the nucleus in the cereal lineages. For example, there is a functional copy of rpl5 in the mitochondria and the nucleus in wheat but it is absent from the mitochondria in rye and maize. In oat mitochondria, rpl5 appears to be a pseudogene and in barley, rearrangements at the 3' end and low transcript levels question its functionality.
The characterization of transcription initiation sites, processing sites and 3' ends for these two loci reflect the relaxed nature and flexibility of signals exploited by plant mitochondria. This research supports the significant role of post-transcriptional events in the regulation of gene expression in plant mitochondria.
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Kohl, Thomas Oliver. "An investigation into the development of plant-derived vaccines against human papillomavirus type 11 and Cottontail rabbit papillomavirus." Doctoral thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/7433.
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Includes bibliographical references (leaves 207-241).The principal object of this thesis was to investigate the feasibility of developing a novel plant-derived vaccine against Human papillomavirus type 11 (HPV -11), the causal agent of genital warts and laryngeal condylomas. A secondary objective was a proof-of-concept study using Cottontail rabbit papillomavirus (CRPV), as this is a viable animal model for human papillomavirus vaccines. Accordingly, I investigated and compared the potential of two different plant expression systems.
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Sarrión, Perdigones Manuel Alejandro. "Design and development of modular DNA assembly tools for Multigene Engineering and Synthetic Biology in Plants." Doctoral thesis, Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/35399.
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The post-genomics era has put at the disposal of modern plant breeders an endless list of genetic building blocks for the design of new biotechnological crops. After a first wave of single-gene transgenic with controversial public acceptance, genomic information and technology is paving the way for increasingly complex designs based in multiple gene engineering. Those designs aiming at the production of inexpensive health-promoting compounds are most likely to be welcomed by consumers. In this project we plan to develop new multigene assembling tools.
During this PhD, a standardized collection of interchangeable genetic parts (including promoters, CDS, P-DNAs, etc) and vectors will be developed. The collection, inspired in Synthetic Biology standards, will be made easy-to-assemble in an interchangeable, semi-idempotent and seamless fashion by the addition of flanking recognition sites of type IIS Restriction endonucleases. The construction of the collection will facilitate multigene engineering and will constitute a first step towards enabling Synthetic Biology in plants.Sarrión Perdigones, MA. (2014). Design and development of modular DNA assembly tools for Multigene Engineering and Synthetic Biology in Plants [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/35399
TESIS
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Child, Robert Joseph. "The evolution of BARREN INFLORESCENCE1 and related AUX/IAA genes in angiosperms." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527538.
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The plant hormone auxin plays a major role in shaping plant morphology and development, but the gene networks regulating its synthesis and transport are incompletely known. The maize BARREN INFLORESCENCE 1 (BIF1) gene has recently been cloned and shown to play an important role in the early stages of polar auxin transport. Auxin is synthesized in shoot tips and transported basipetally through the plant shoot and acts as a morphogen by facilitating the degradation of transcriptional repressors in a concentration dependent manner. The AUX/IAA gene family encodes transcriptional repressors that regulate a subset of plant developmental responses governed by the transcription of early auxin inducible genes in plants. Although the maize BIF1 gene is a member of the AUX/IAA gene family, the co-ortholog(s) of BIF1 in Arabidopsis thaliana was not known prior to this research.
Bayesian phylogenetic reconstruction placed maize BIF1 in a clade sister to Arabidopsis thaliana AtIAA15. The BIF1 lineage has undergone two gene duplications since the divergence of the early grasses. Molecular evolutionary analyses by maximum likelihood suggest that the BIF1 alignment is under strong purifying selection with positive selection acting on a glutamine residue located in a functional region associated with AUX/IAA protein dimerization in one clade of BIF1 paralogs, the BIF1-Like2 (BIF1L2) clade. A character reconstruction analysis using maximum parsimony estimated an adenine to cytosine transversion at the base of the BIF1L2 clade changed a glutamine into an alanine residue in this functional region. Expression of BIF1 orthologs is conserved in floral meristems in the eudicot AtIAA15 clade containing the taxa Erianthe Guttata, Arabidopsis thaliana, Medicago truncatula, however grass BIF1L2 expression has diverged within the PACMAD – BEP clade, specifically in rice, where BIF1L2 expression is reported to have moved into root tissue. These results suggest that BIF1 paralogs has changed following a second round of gene duplication in the grasses. Taken together, a change in localized expression in these sequences, and positive selection acting on a glutamine-rich region of the protein-protein binding motif could imply that BARREN INFLORESCENCE1-like2 proteins are probably interacting with a new set or subset of AUXIN RESPONSE FACTOR (ARF) binding partners, and that neofunctionalization has occurred in the BARREN INFLORESCENCE1-like2 clade.
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Mahoney, Kevin L. "Development of Techniques for the Cultivation of Fish in a Converted Wastewater Treatment Plant." NSUWorks, 1999. http://nsuworks.nova.edu/occ_stuetd/329.
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The town of Davie, Florida, converted a defunct wastewater treatment plant into an aquaculture facility. A feasibility study was conducted of the facility and it was determined that tilapia would be best suited for growout at the facility. Oreochromis aureus and a hybrid of Oreochromis niloticus are the two fish currently being grown at the aquaculture facility. A review of fish culture suggests that a filtration system that influences water quality will be needed to grow healthy fish. Furthermore, harvesting will prove to be very difficult in the deep tanks, and a most practical methodology for harvesting must be devised.
Two filters were built-one from PVC pipe, nylon cord, and plastic biobarrels, and the other from a PVC frame and wetland plants. Water was run through the filters for 10 days prior to taking water samples. Water samples were then collected, frozen, and transported to the lab for analysis. The water samples were analyzed for ammonia, nitrate, and phosphate concentrations. The results indicate that the filter made of the biobarrels caused a significant increase in nitrate concentrations in the water. The results also indicate that the biobarrel filter was significantly more effective than the hydroponics filter in influencing water quality. There was no significant difference in ammonia or phosphate levels between the two filters.
Three separate harvesting nets were compared. One net was built of hog wire, the second net was made of a stretchable nylon mesh, and the third was made of a nonstretchable nylon mesh. There was no significant difference in the three nets used for harvesting, and, according to the catch per unit effort, it was determined that the nets were ineffective as harvesters. However, the nets did prove to be capable of crowding fish of a desired weight in such a way that facilitated catching the fish with a cast net.
Two different sized cast nets were analyzed to determine their effectiveness in sampling. Each net was cast into the same depth of water 30 times and the catches per unit effort were compared. This was repeated for twelve depths. It was found that catch size was significantly different for the two nets and that catch per cast increased with decreasing depth until shallow water (<5 >ft) prevented proper net closure. However, there was no significant difference in determining the number of fish per unit volume when comparing the catches of each net.
Finally, a comparison was made between two species (Oreochromis aureus and Oreochromis niloticus hybrids) to determine which species was more suited for growth at the Aquaculture Center. Random samples of various sizes for each species were taken simultaneously for a period of time. This information was used to calculate and compare the growth rates of the two species. It was determined that, although the growth rate of blue tilapia was greater than that of hybrid tilapia, hybrid tilapia had a higher overall production rate, possibly because it could tolerate higher stocking densities.
These results helped answer several questions about culture methods, and modifications to the facility, based on these results, were ultimately made.
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Regnard, Guy Louis. "Development of a potential challenge model and plant-produced vaccine candidate for beak and feather disease virus." Doctoral thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15690.
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Psittacine beak and feather disease (PBFD), the most prevalent viral disease affecting psittacines, is caused by beak and feather disease virus (BFDV). An outbreak of the disease has been reported in wild endangered Cape parrots (Poicephalus robustus), which is endemic to South Africa. No treatment or vaccine is commercially available. In this study, an investigation into the outbreak was undertaken. BFDV diversity was assessed and viral load and clinical signs correlated. A plant-produced BFDV subunit vaccine was produced in parallel with a corresponding challenge model. Cape parrots were assessed and 53 blood samples collected. Viral load was determined using quantitative real-time PCR (qPCR), and 22 BFDV full-length genome sequences acquired to infer phylogenetic relatedness. The capsid gene (cp) was optimised for transient Agrobacterium-mediated expression in whole-plant Nicotiana benthamiana (N. benthamiana). Virus-like particles (VLPs) were purified and analysed using transmission electron microscopy. Virions from a Palm cockatoo (Probosciger aterrimus) were purified and a BFDV dsDNA molecular clone was synthesised and replication assessed in 293TT mammalian cells and N. benthamiana using rolling circle replication and qPCR. Two distinct BFDV phylogenetic clusters were reported for Cape parrots, and a direct correlation was seen between viral load in the blood and clinical signs in PBFD-afflicted birds. The CP was successfully expressed in N. benthamiana, and increased through optimisation of Agrobacterium infiltration density and the inclusion of the NSs silencing suppressor. The CP formed VLPs, which were shown to be morphologically similar to infectious virions. The dsDNA molecular clone was shown to replicate autonomously in mammalian 293TT cells, and in plants with the assistance of the Bean yellow dwarf virus replication associated protein (Rep). BFDV genetic diversity in Cape parrots highlights the importance of ensuring new strains are not inadvertently introduced into the wild. This is the first systematic investigation of virus diversity in Cape parrots and assessment of BFDV viral load in a wild psittacine population. The CP was successfully produced in planta and presence of VLPs suggests the possibility of developing pseudovirions. This is the first reported replication of BFDV in tissue culture, and will greatly expand the scope of available research.
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Hocker, Anna Margaret 1960. "Development of procedures towards the somatic hybridization of alfalfa and Medicago marina L." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/278034.
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Protoplasts were isolated from mesophyll tissue, callus and seedling cotyledons of Medicago sativa L. cv. Regen S and the halophyte M. marina L. Cotyledon protoplasts of Regen S were cultured in protoplast and cell culture media used previously for alfalfa protoplast culture and in media that had been simplified. There were no differences in the plating efficiencies of protoplasts cultured in the simple and complex media, but cells produced in the latter were greener and they colonized sooner. Protoplasts of M. marina grew at one-half the rate of Regen S protoplasts. Etiolated cotyledon protoplasts of Regen S were fused at 31°C using a solution containing PEG, DMSO and calcium at high pH. The frequency of fusion was 16% of the surviving protoplasts. These methods for protoplast isolation, culture and fusion should be useful in the somatic hybridization of alfalfa and M. marina.
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Sampson, Dennis Archie. "An assessment of the evolutionary stability of distyly in Hedyotis caerulea (Rubiaceae)." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1296756691.
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Wang, Yan. "The Role of the Homeobox Gene ATHB16 in Development Regulation in Arabidopsis thaliana." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-4983-2/.
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Bandawe, Gama. "Expression of HIV-1 subtype C nef in E. coli and Nicotiana benthamiana : development of plant-based vaccines for HIV." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/4242.
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Bibliography: leaves 126-145.Expression of the nefgene from HIV-1 subtype C in Nicotiana benthamiana was carried out using a TMV -based vector with the aim of developing a plant-based candidate vaccine for HIV-1. The nef gene of the DU151 isolate of mV-l subtype C taken from a recently seroconverted individual was amplified by PCR with a deletion of 59 amino acids from the cytotoxic N-terminal. The amplified gene was inserted into a bacterial expression vector pProEXHTb for rapid expression of Nef protein, which was used as a diagnostic tool in the development of an indirect ELISA assay for detection of Nef in Nicotiana benthamiana. An indirect ELISA assay was developed using a commercially available polyclonal anti Nef antiserum raised in sheep. The role of codon optimization in expression of Nef in benthamiana was investigated. A synthetic nef gene was constructed based on the codon usage of benthamiana. The plant codon optimized gene and the wild type nef genes were inserted into the TMV -based vector pBSG1057. RNA transcripts from both constructs were used to infect young benthamiana plants. Expression of nefmRNA was confirmed by RT -PCR analysis of total RNA extracted from plants inoculated with respective constructs. The Nef protein was expressed at low levels which were detectable by ELISA. Nef was detectable by Western blot after concentration of plant extract using a membrane filter device. Quantitative analysis of Nef expression in plants was done by western blot on concentrated plant extract from three separate infections. Codon optimization of the nef gene improved the expression of Nef by a factor of about two.
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Angobe, Aune Tuyoleni. "Development of a plant-made immunoassay for the detection of Porcine circovirus infections in South African swine herds." Master's thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33629.
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Porcine circovirus type 2 (PCV-2) is considered the major cause of porcine circovirusassociated diseases and is one of the major pathogens in swine producing countries. PCV-2 is a non-enveloped virus with a single stranded circular DNA genome of about 1.8 kb. This encodes the single capsid protein (CP) which is highly immunogenic, as well as a replication-associated protein. Recombinantly expressed CP can selfassemble into virus-like particles (VLPs) that are structurally and immunogenically very similar to native virions. Current commercially available diagnostic kits are VLPbased and are effective at detecting PCV-2 antibodies in sera. However, these diagnostic assays are expensive, therefore limiting their use in developing countries. Plant-based transient expression systems have recently been investigated to express PCV-2 CP for a cheaper diagnostic reagent. The aim of this study was to develop an inexpensive lateral flow device to be able to test for PCV infection in pig herds. Production of PCV-2 CP in Nicotiana benthamiana via transient Agrobacterium-mediated expression was optimised by comparing two expression vectors, pEAQ-HT and pCBP2, and VLPs were also expressed in Escherichia coli. VLPs produced in plants and in E. coli were used to set up a lateral flow device. In addition, various purification methods of VLPs such as ion exchange chromatography (IEC) and sucrose gradient ultracentrifugation were explored to obtain pure VLPs free of bacterial contamination. The VLPs were successfully expressed in N. benthamiana with both pEAQ-HT and pCBP2, and VLPs were subsequently purified on discontinuous sucrose gradients by ultracentrifugation. The assembly of the CP was assessed by transmission electron microscopy, which showed the presence of assembled VLPs. To further purify the VLPs IEC was used, and fully assembled VLPs which were free of contamination were prepared. Purified VLPs expressed in plants and E. coli were successfully used as coating antigen in lateral flow devices, which were able to detect PCV-2 CP antibodies in CP-immunised rabbit sera. E. coli-made VLPs showed higher affinity to PCV-2 antibodies compared to plant-made VLPs. In conclusion, this study has successfully demonstrated the potential to use a plantbased transient expression system to produce affordable diagnostic reagent, especially for developing countries. This is the first study that expressed PCV-2 VLPs using a pCBP-2 expression vector and used PCV-2 VLPs as a coating reagent in the development of a lateral flow test as a proof of concept.
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Satterfield, Erica. "The Role of Mitogen-activated Protein Kinases in the Regulation of Plant Development." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1775.
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Mitogen-activated protein kinases are part of an evolutionarily conserved protein phosphorylation cascade which serves essential regulatory functions in eukaryotic organisms. Although the role of MAPKs in the regulation of a plant’s response to environmental stress and plant defense has been well established, very little is known about their role in the regulation of plant developmental processes. In order to examine the role of MAPKs in plant growth and development, a strong mammalian MAPK phosphatase (MKP-1), which is known to inactivate MAPKs in plants, was introduced into tobacco plants. In tobacco plants, MKP-1 overexpression altered plant responses to the phytohormones, ethylene and cytokinin. Tobacco plants expressing MKP-1 flowered earlier and senesced later than wild-type. Additionally, these plants exhibited similar floral morphology as flowers from ethylene-insensitive tobacco plants. These observed phenotypes seem to depend on the protein phosphatase activity, as transgenic lines expressing an inactive form of MKP-1 (MKPCS) did not show the same phenotypes. Furthermore, both tobacco and Arabidopsis MKP-1 transgenic plants exhibited increased shoot regeneration when compared to wild-type plants, suggesting increased cytokinin sensitivity. In an attempt to elucidate the mechanism by which MKP-1 affects plant growth and development, expression of selected genes were analyzed using RT-PCR. MKP-1 transformed tobacco plants exhibited downregulated expression of an ethylene biosynthesis gene (NtACO) and upregulated expression of a pathogenesis-related gene (PR-1b), similar to gene expression studies previously conducted in plants with increased production of cytokinin. The same MKP-1 transgenic plants also exhibited upregulated expression of the flowering time gene, FT. Results from this study indicate that constitutive expression of MKP-1 may interfere with ethylene-related MAPK pathways, which normally serves to restrict plant growth during times of environmental stress. The reduced responses to ethylene resulted in elevated sensitivity to cytokinin, promoting an enhanced shoot regeneration phenotype.
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Bec, Sladana. "ROLE OF THE SEXUAL CYCLE IN DEVELOPMENT OF GENOTYPIC AND PHENOTYPIC DIVERSITY IN Gibberella zeae." UKnowledge, 2011. http://uknowledge.uky.edu/plantpath_etds/2.
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Gibberella zeae (anamorph Fusarium graminearum) is a homothallic ascomycete pathogen that is responsible for causing Fusarium head blight (FHB) of wheat and small grains. In addition to causing a reduction in yield, harvested grain is frequently contaminated with trichothecene mycotoxins that are harmful for human and animal health. Use of wheat varieties with resistance to FHB is an important strategy to lower its impact. In order to produce varieties with durable resistance, we must understand the origin and degree of genetic diversity present in the pathogen population. In my research, I focused my efforts on an investigation of the role of mating and sexual development in the generation of genotypic and phenotypic variability in G. zeae. The goal of one part of my work was to develop new genetic markers that can be used to monitor out-crossing and genetic diversity in the population. I also optimized gene deletion protocols for G. zeae so that I could produce mutant and control strains to address my research hypothesis that MAT genes play a direct role in pathogenicity. Application of novel repetitive RFLP probes to a group of G. zeae isolates originating from and near Kentucky revealed a surprisingly high degree of diversity in these local populations. Diversity between locations was greater than that within locations, suggesting the relative importance of local inoculum sources. The probes were also useful as genetic markers for segregation analysis. I crossed two genetically closely related, and commonly used, laboratory strains of G. zeae and found that this resulted in transgressive segregation for both aggressiveness and toxigenicity. I showed that the very high and very low levels of aggressiveness and toxigenicity in transgressive segregants are heritable. I also showed that selfing produced a higher degree of diversity in these traits among the progeny than was observed among conidial progeny. This suggests the presence of epigenetic factors that impact pathogenicity. Sexual behavior in G. zeae is under the control of MATing type genes. I deleted the complete MAT1 locus, and the MAT1-1-1, and MAT1-2-1 genes separately. Deletion of each of the targeted sequences produced the expected shifts in fertility phenotype. The mat1KO strains became asexual, while mat1-1-1KO and mat1-2-1KO strains shifted to obligate heterothallism. Deletion of the MAT1-1-1 and MAT1-2-1 genes had a negative effect on aggressiveness and mycotoxin production in planta, but deletion of the complete MAT1 locus had no effect. The set of mutant and ectopic control strains that I generated will be a useful asset that will be made available to the research community.
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Sieberg, Maureen A. "Heritability and development of the free fatty acids and acylglycerideconstituent fatty acids in Vernonia galamensis oil." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280501.
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Since the mid-1970's, there has been active research on the development of Vernonia galamensis (Cass.) Less. as a potential new oilseed crop. Vernolic acid (cis-12:13-epoxy-cis-9-octadecenoic acid) comprises 70--75% of vernonia oil and is chemically reactive, affording it a variety of industrial applications. A concern in the domestication of an oilseed crop is to establish a breeding program to improve oil quality traits. The objectives of this research were to (1) develop a rapid procedure for seed analyses; (2) determine the development of vernonia oil; and (3) estimate the narrow-sense heritability (h 2) of oil quality traits. Successful separation of free fatty acids (FFA) and acylglycerides from small vernonia seed samples was achieved using aminopropyl solid phase extraction columns. Acylglycerides were eluted with a mixture of chloroform and isopropanol, while FFA were eluted with a mixture of acetone and trifluoroacetic acid. Four breeding lines from a collection of Vernonia galamensis held at the US Water Conservation Laboratory in Phoenix, AZ were used for the oil development study and grown in field trails in Phoenix and Tucson, Arizona. Seeds were collected on nine different days after flowering over the course of seed maturation. Seed samples were analyzed for FFA, acylglyceride constituent fatty acids, total acylglycerides, and total oil. In each breeding line, FFA content changed significantly throughout the course of the measurement period, and synthesis of acylglycerides constituent fatty acids followed a previously described pathway proceeding from C16:0 to C18:0 to C18:1 to C18:2 to C18:1 epoxy. Vernolic acid increased late in the measurement period, while total acylglycerides and total oil increased steadily over the period. Mature vernonia seed exhibited substantial variation in the amount of FFA, acylglyceride constituent fatty acids, total acylglycerides, and total oil. Sixty-nine half-sib families were created to study the heritability of FFA, vernolic acid, acylglycerides, and total oil production. Mature capitula were collected and analyzed individually for oil constituents. Narrow sense heritability estimates for these four oil quality traits were: FFA = 33%, vernolic acid = 65%, acylglycerides = 47%, and total oil = 50%. The results indicate potential for progress in selection for these traits.
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Frantz, Jonathan M. "Determining the Factors That Control Respiration and Carbon Use Efficiency in Crop Plants." DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/6600.
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In the literature on plant respiration, there are two viewpoints concerning the source of respiratory control: supply (photosynthate availability) or demand (temperature dependent) limitations. While different studies indicate the primary dependency for respiration is either the supply or demand side, the two paradigms cannot both be true. The relative importance of each paradigm may depend on a number of factors including period of time during which respiration is measured, phase of plant development, environmental conditions, and species.
Studies were performed using continuous CO2 gas-exchange instrumentation to monitor short- and long-term changes in whole canopies of lettuce, tomato, soybean, and rice in response to changes in light and temperature during vegetative growth. Respiration in all crops was less sensitive to temperature than previously reported. This is likely due to large amounts of temperature-insensitive growth respiration as a fraction of total respiration during early growth. Carbon use efficiency (CUE) decreased with warm night temperatures, but the change was too small to decrease the final dry mass or carbon gain after night temperatures decreased. Canopies with constant day/night temperature had the same CUE, in elevated CO2 (1,200 μmol moJ- 1), regardless of temperature. In ambient CO2 (400 μmol mol-1), CUE decreased significantly when temperatures were above 32C.
Applying shade initially decreased CUE because of low photosynthesis and high respiration. After about 12 days, canopies acclimated, based on recovery of CUE. Different species acclimated to shade to different extents, but no interaction was evident between light and shade stress. These data were used to predict changes in photosynthesis, respiration, and carbon use efficiency given light, temperature, and CO2 concentrations.
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Ozkan, Korhan. "Role Of Nitrogen In Submerged Plant Development In Mediterranean Climatic Zone - A Mesocosm Experiment." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610083/index.pdf.
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The effects of increasing nitrogen and phosphorus loading on submerged macrophyte development was tested in a mesocosm experiment for three months. Experiment consisted of three NO3-N loadings with factorial of two PO4-P loadings in a fourfold
replicated design. Twenty four enclosures placed at one meter depth were isolated from the lake but kept open to sediment and atmosphere. Each enclosure stocked with ten Myriophyllum spicatum shoots with underyearling fish to reduce zooplankton grazers.
Biweekly sampling and weekly nutrient additions were performed for three months. Mean total nitrogen (TN) concentrations sustained in nitrogen treatments through out the experiment were 0.52, 1.99, 8.07 mg/l. Both phosphorus treatments
converged to a mean concentration below the targeted level, ranging between 0.05-0.1 mg/l TP. In comparison to mesocosm studies in temperate lakes, higher assimilation rates for nutrients were observed in Lake Pedina. Due to extraordinarily high evapotranspiration and drought in 2007, the water level decreased 0.6 m in enclosures.
Total macrophyte biomass remained indifferent to nutrient treatments with continuous growth and failed to validate any direct or indirect negative effect of increasing nutrient concentrations. Phytoplankton biomass differed significantly among factorial treatments but remained low, while periphyton biomass differed among nitrogen treatments. In comparison with other studies the phytoplankton biomass remained low and the periphyton biomass became high for reference TP concentrations, indicating a competitive advantage of periphyton over phytoplankton on nutrient utilization in the enclosures. Zooplankton:phytoplankton biomass ratio was low throughout the experiment and zooplankton community mainly consists of smaller species, reflecting high predation pressure.
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Bartholmes, Conny. "Regulation of Morphogenesis of Lateral Organs in the Basal Eudicot Eschscholzia californica." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1305123248.
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Nair, Meera. "UNDERSTANDING THE ROLE OF MEMBRANE LOCALIZED UGT80B1 ENCODING FOR UDP-GLUCOSE: STEROL GLUCOSYLTRANSFERASE IN PLANT DEVELOPMENT." UKnowledge, 2014. http://uknowledge.uky.edu/pss_etds/54.
Full textAbstract:
Sterols have been identified as major components of membrane lipids that are part of specialized membrane domains necessary for organizing events such as polar protein targeting and signal transduction in plants, fungi and animals. However a common modification of sterols is the addition of sugar moieties via glycosylation abundantly found in plants. An exact physiological role for such diversification of sterols in plants is still unknown. Using reverse genetics and transcriptomics we show that UDP-glucose: sterol glucosyltransferase encoded by UGT80B1 is necessary for correct epidermal patterning in Arabidopsis root. Patterning of hair cells (trichoblasts) and non-hair cells (atrichoblasts) in the epidermis of the Arabidopsis root involves signaling through SCRAMBLED (SCM), a plasma membrane localized LRR-RL kinase. Feedback regulation via the transcriptional regulatory complex containing R2R3-MYB transcription factor WEREWOLF (WER) represses SCM and activates the homeodomain-leucine-zipper protein GLABRA2 (GL2) in atrichoblasts. Evidence suggests symplastic connections between cells, known as plasmodesmata, establish passage ways for single-repeat R3-MYB transcription factors to activate SCM expression in trichoblasts. Mutations in UGT80B1 cause atypical localization patterns of GL2, WER, and SCM in the root epidermis. The ugt80B1 formed fewer trichoblasts in comparison to wild-type. A translational fusion of UGT80B1 to GFP localizes to the ER, plasma membrane and to sites that appear to be plasmodesmata-associated desmotubules. Ultrastructural analysis revealed abnormalities in plasmodesmata formation and morphology in ugt80B1 mutants. Steryl glucoside profiling indicated deficiencies in specific glycosylated sterol compounds in roots. This study identifies UGT80B1 as a novel membrane component that is critical for plasmodesmata morphogenesis and cell-fate determination in the root epidermis. A model is proposed in which UGT80B1 activity provides spatially discreet sterol and steryl glucoside architecture within the plasma membrane to anchor the SCM receptor and within plasmosdesmata to facilitate intercellular movement of R3-MYB regulatory proteins underlying proper differentiation of trichoblasts versus atrichoblasts. Moreover, evidence from reverse genetics, proteomics and live cell imaging point to a actin dependent localization of UGT80B1 at the vesicle rich zone of root hair tip. This localization actively supports root hair elongation via tip growth, possibly by membrane modifications required for vesicle trafficking.
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Canto, Pastor Alex. "Small RNAs in tomato : from defence to development." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/273780.
Full textAbstract:
RNA silencing is a major regulator of gene expression in plants, controlling from development to transposable element silencing and stress responses. As part of the silencing machinery, micro (mi)RNAs orchestrate silencing of their targets, either directly or through cascades of secondary small interfering (si)RNAs. To investigate the role of RNA silencing in plant immunity, I chose to focus on the miR482/2118 family, because of its diversity and presence in many plant species since the appearance of seed plants, with most genomes containing several copies, and because its members target sequences conserved in a family of disease resistance genes known Nucleotide biding site leucine-rich repeat (NLR) genes. In this dissertation, I wanted to address the extent to which the miRNA family and its derived phasiRNAs regulate expression of defence genes as well as contribute to quantitative resistance in crops. I explore the structural differences of miR482/2118 members in Solanum lycopersicum and show that they are functionally significant and affect their target preferences. My approach was based on small RNA sequencing and degradome data to characterize targets of these miRNAs, including the recently discovered tomato TAS5 locus. I also generated transgenic tomatoes constitutively expressing target mimic RNAs that sequester different miR482/2118 members. These tomato mimic RNA lines were less susceptible than their non-transgenic precursors to pathogens Phytophthora infestans and Pseudomonas syringae. Additionally, I investigated the role of small RNAs and their effector proteins during vegetative and reproductive development in tomato. I employed transcript and small RNA sequencing and CRISPR-Cas9 techniques of gene editing to investigate the impact of these factors in gamete viability and transposable element silencing in vegetative meristems. The results presented here provide new evidence about the extent that RNA silencing contributes to the regulation of vital processes in plants. My study primarily explores the extent to which structural differences between the members of the miR482/2118 family affect their range of action, and the use of target mimics against these miRNAs as biotechnological approach for enhancing disease resistance in highly bred cultivars.
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Wierzba, Michael. "A Family of Four LRR-RLKs Modulate Development and Defense Signaling in Arabidopsis thaliana through Interaction with the Co-receptor BAK1." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/312668.
Full textAbstract:
Receptor-like kinases (RLKs) are encoded for by one of the largest gene families in Arabidopsis and represent the predominant form of cell surface receptors in plants. RLKs mediate signal transduction in diverse processes including steroid-mediated growth pathways, pathogen-triggered innate immune responses. Here I present characterization of mutant phenotypes, expression patterns, and genetic interactions for the BAK1 INTERACTING RECEPTOR (BIR) family of Leucine-rich Repeat-RLKs, three members of which have had no previous characterization. Furthermore, I show that cell death, aerial growth, and lateral root development defects in bir1-1 are suppressed by mutations of the LRR-RLK co-receptor BRI1-ASSOCIATED KINASE 1 (BAK1); I identify a novel primary root growth phenotype in bir1-1 mutants, as well as a lateral root development phenotype for bir3 mutants; and primary root growth and aerial defects in bir3.bir4;bak1 triple mutants. Using an allelic series of bak1 mutations I show that bir phenotypes are dependent upon particular functions of BAK1, and propose that the BIR family exhibits a novel function, previously undescribed for LRR-RLKs, as regulators of co-receptor/ligand-binding receptor complex specificity.
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Chun, Elizabeth M. "Developing a Recombinant Plant Virus Nanoparticle Vaccine for Rift Valley Fever Virus." Scholarship @ Claremont, 2019. https://scholarship.claremont.edu/scripps_theses/1345.
Full textAbstract:
Rift Valley Fever (RVF) is an emerging infectious disease found in both livestock and humans. RVF is associated with high abortion and mortality rates in livestock and can be fatal in humans. As such, RVF is economically and socially significant to affected smallholder and subsistence farmers, those infected, and national livestock industries. However, Rift Valley Fever virus (RVFV) vaccines are not commercially available outside of endemic areas or for humans, and current vaccines are limited in their safety and efficacy. A plant-based, viral nanoparticle vaccine offers a more affordable alternative to conventional vaccines that is safe, rapidly producible, and easily scalable, better meeting the needs of impacted communities. This project focuses on assessing the potential of using a Nicotiana benthamiana plant expression system to generate recombinant tobacco mosaic virus (TMV) nanoparticles displaying RVFV glycoprotein epitopes. Eight TMV-RVFV glycoprotein constructs were designed. Five TMV-RVFV constructs were successfully cloned, and four recombinant TMV constructs were successfully expressed in planta. The antigenicity of these constructs was examined for their possible use in RVFV vaccine development.
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Mitra, Sayantan. "Arabidopsis Cohesin proteins: WAPL, CTF7 and PHD finger proteins: MMDL1, MMDL2 are essential for proper meiosis, gamete development and plant growth." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1517605898967702.
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