Dissertations / Theses: 'Science / Botany'

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Van, Ruymbeke Christine. "Science and poetry in medieval Persia : the botany of Nizami's Khamsa /." Cambridge : Cambridge University Press, 2007. http://catalogue.bnf.fr/ark:/12148/cb41209098p.

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Lombaard, Deidré. "Natural Science teacher attitudes and Pedagogical Content Knowledge for teaching Botany." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/45870.

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This South African study investigated a sample of Grade 4 to 7 Natural Sciences teachers’ attitudes towards botany and botany teaching and these teachers’ botany Pedagogical Content Knowledge (PCK). It explored whether a relationship exists between teachers’ attitudes towards botany teaching and their PCK. The study provides an overview of international and South African literature and research on the underrepresentation of botany and the teaching of botany in Natural Sciences classes. Throughout the study insight is provided on the universal problems of plant blindness and negative attitudes towards botany and botany teaching in the Natural Sciences classroom. Data were collected during teachers’ interviews, class observations and analyses of lesson plan documents. The results indicated that most teachers harbour negative attitudes towards botany and botany teaching. There are various reasons for this negativity such as past experiences in botany training, zoochauvinism and plant blindness. The Pedagogical Content Knowledge of teachers in this study was insufficient. It was found that teachers’ attitudes towards botany teaching influence their PCK and teachers’ PCK can, in turn, influence teacher attitudes towards botany, which can affect the teachers’ ways of teaching. This study confirms that problems of plant blindness, zoochauvinism and negativity towards botany and botany teaching that occur elsewhere in the world are also prevalent among South African teachers. This confirmation casts doubts on Natural Sciences teachers’ botany PCK. This study adds to the literature on botany teaching and PCK in the South African context
Dissertation (MEd)--University of Pretoria, 2014.
tm2015
Science, Mathematics and Technology Education
MEd
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Jamonnak, Suphanut. "LITTLE BOTANY: A MOBILE EDUCATIONAL GAME FOR GARDENING." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1479080799053076.

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Cornish, Caroline. "Curating science in an age of empire : Kew's Museum of Economic Botany." Thesis, Royal Holloway, University of London, 2013. http://repository.royalholloway.ac.uk/items/f5bcc23c-e039-e81b-8f25-2156ff0f662d/7/.

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This thesis considers the history and significance of the Museum of Economic Botany at the Royal Botanic Gardens, Kew, focussing especially on the period from its opening in 1847 to the eve of the First World War. Looking specifically at the Museum's collection of wood specimens and artefacts, it seeks to understand the nature of economic botany during this period, and to evaluate the contribution made to the field by the Kew Museum. Through examination of the Museum's practices, networks, spaces, and objects, it sets out to address the question: how do museums produce scientific knowledge? Part One sets the context. Chapter One provides a brief historical account of nineteenth-century economic botany and the Museum. Chapter Two offers a critical overview of literatures on Kew and economic botany; on the role of place in the production, circulation, and reception of scientific knowledge; and on the role of the public museum in Victorian science and culture. It also outlines the conceptual framework of the thesis. Chapter Three presents an account of the methodology and sources. Part Two highlights museum practices. Chapters Four to Six are devoted respectively to the practices of ‘exhibition' (the spatialities, rhetorics, and rationalities of display); ‘instruction' (the educational uses of museum objects); and ‘supply' (the circulation of objects). Part Three turns to specific objects and their biographies. Chapters Seven and Eight trace respectively the production, circulation and reception of a totem pole from British Columbia and a timber trophy from Tasmania, to demonstrate how objects acquire diverse meanings in diverse contexts, and how they are used to impart meaning to particular sites. In conclusion, Chapter Nine reflects on the cumulative findings of the thesis and on its potential outcomes, and it looks beyond the thesis to recommend areas for future research and practice.

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Seligo, Carlos. "The origin of science fiction in the monsters of botany : Carolus Linnaeus, Erasmus Darwin, Mary Shelley /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/9361.

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Reay, Nicky. "An evaluation of the importance of plant resources to rural communities - a case study of Heuningvlei in the Cederberg." Bachelor's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/23931.

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Within the framework of living resource conservation as advocated by the world Conservation Strategy, this case study investigates the utilitarian value of indigenous plant resources as a supplementary or "hidden" income for a rural community at Heuningvlei. The objectives of the study were to document the rapidly disappearing customary knowledge regarding the utilisation of plant resources, to gain an indication of whether a sustainable method of utilisation exists within the case study community, and to interpret the results in terms of conservation objectives.

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Hart, Jaynee E. "Biochemical and genetic approaches to modulate phototropin photoreceptor sensitivity." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/30991/.

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The necessity of light for plants to sustain their autotrophic lifestyle has made the optimization of growth to maximize light capture a crucial strategy for survival in light-limiting environments. Increases in light capture can be achieved through alterations in plant architecture, such as modifications to leaf position and stem length. Responses to the light environment are mediated by a network of photoreceptor proteins, which sense specific wavelengths of light and respond to light excitation by initiating signaling. Higher plants respond to red and far-red light through the phytochrome family, blue light through cryptochromes, the zeitlupe family, and phototropins, and UV-B light through the UV RESISTANCE LOCUS 8 photoreceptor. Of these photoreceptor proteins, the phototropins (phots) are perhaps the most closely tied to photosynthetic efficiency. Higher plant phots, phot1 and phot2, mediate leaf expansion to maximize the surface area available for light capture as well as control movement and positioning responses, such as petiole inclination, movement towards more favorable light conditions through phototropism, and, at a cellular level, chloroplast movement. Furthering the role of phots in optimizing responses upstream of photosynthesis, phot1 and phot2 also control stomatal opening in response to blue light, allowing the uptake of carbon dioxide into the leaf for fixation into sugars. In general, these responses are redundantly coordinated by both phot1 and phot2, with phot1 acting as the primary sensor due to its greater sensitivity. Because of the profound effect phots have on photosynthetic competence, the studies presented here examine phot1 with the goal of understanding the physiological role of phot1 sensitivity in plants and explore the possibility that enhancing phot1 sensitivity could increase plant growth. Phots consist of two N-terminal light sensing LOV (Light, Oxygen or Voltage) domains, LOV1 and LOV2, coupled to a serine/threonine kinase domain at the C-terminus. Each of the LOV domains bind a flavin mononucleotide (FMN) chromophore that allows these domains to perceive blue light. In darkness, FMN is non-covalently bound within each of the LOV domains, which repress the activity of the kinase domain. When FMN is excited by blue light, a covalent bond is formed between a conserved cysteine residue present within each LOV domain and FMN. LOV2 specifically is coupled to the kinase domain through two alpha helices, Jα and A’α, which become disordered following the formation of the covalent photoadduct. The unfolding of these alpha helices relieves repression of the kinase domain, initiating signaling. The onset of phot1 signaling is characterized by phot1 autophosphorylation and the dephosphorylation of the phot1 signaling partner NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3). Over time, the covalent photoadduct decays and phot1 returns to its inactive dark state, completing the photocycle. The chemistry of the phot1 photocycle in vitro is understood in detail, but its downstream signaling following activation remains relatively elusive, with only a handful of signaling partners and phosphorylation substrates identified. For the sensitivity of phot1 to be thoroughly explored, how the phot1 photocycle affects plant growth as well as how phot1 activity is modulated by signaling partners needed to be addressed. Therefore, a biochemical approach was used to introduce mutations within LOV2 to slow its dark reversion to prolong signaling and investigate how this modulates phot1 sensitivity in vitro and in planta, and, secondly, a genetic strategy was employed to uncover whether any signaling processes can modulate phot1 sensitivity in plants. Compared to other photoreceptors that receive blue light through LOV domains, dark reversion of phot1 following a light stimulus is relatively fast, with the lit state lasting only approximately 15 minutes, while other LOV domains remain activated for many hours. To generate slow photocycle mutants of phot1, previous characterizations of slow photocycling LOV domains were exploited to engineer the phot1 photocycle to have a slower dark reversion by introducing mutations into LOV2. To study the photocycle in vitro, the phot1 light-sensing module consisting of the LOV1 and LOV2 domains (LOV1+LOV2) was heterologously expressed and purified from E. coli and the photocycle was measured spectrophotometrically. Using this approach, 13 LOV2 variants were generated and examined to identify slow photocycle mutants. Three mutations in LOV2, N476L, V478I, and L558I, were found to slow the LOV1+LOV2 photocycle in vitro. Following identification, these mutations were introduced into full-length phot1 expressed heterologously in insect cells to verify the autophosphorylation activity of each mutant. Following the characterization of the candidate slow photocycle mutants in vitro, each phot1 photocycle mutant was examined in planta in a phot1phot2 double mutant background to see whether possession of a slow photocycle increased phot1 sensitivity. Of the three candidate mutations, V478I and L558I were verified as possessing a slow dark reversion through the phosphorylation status of NPH3. NPH3 is dephosphorylated in a phot1-dependent manner following light treatment; it was found that in the presence of wild-type phot1, the phosphorylated form of NPH3 is recovered around one hour following a return to darkness after phot1 stimulation by blue light. By contrast, the dephosphorylated state of NPH3 was sustained in phot1-V478I and -L558I for a substantially longer period of time, consistent with a slow phot1 photocycle and prolonged phot1 activation in these mutants. Surprisingly, it was found that these mutants were less sensitive than wild-type phot1 for phototropism in response to low intensity light treatments. Furthermore, biomass accumulation was not increased in the phot1-L558I mutant under growth conditions consisting of very low light. While the photocycle mutants did not exhibit increased sensitivity or growth in response to continuous light treatments, evidence from collaborators indicated that phot1-L558I is more efficient than wild-type phot1 for the chloroplast accumulation response following brief pulses of blue light. While the role of the phot1 photocycle under continuous irradiation remained unclear, this enhanced chloroplast accumulation response implies that the phot1 photocycle is important for its sensitivity to brief irradiations. Unlike phot1, further work with phot2 later indicated that introducing a slow photocycle mutation to phot2 LOV2 can significantly increase growth in a phot1phot2 mutant background under continuous low light. To investigate other factors that may affect phot1 sensitivity, a genetic screen was undertaken in an attempt to identify suppressors of phot1 activity. The LOV2Kinase (L2K) transgenic line, which expresses a truncated version of phot1 in a phot1phot2 double mutant background, was previously found to be unable to respond to low-intensity blue light, though it can mediate phot1 responses when the light intensity is increased. Because L2K possesses this conditional phenotype, random mutations were introduced into the genome of L2K-expressing plants and a screen was established to identify mutants that were able to respond to low-intensity light with the hypothesis that those mutations could lie within suppressors of phot1 activity, allowing L2K to signal under circumstances where it ordinarily could not. Using this approach, three independent candidate suppressor mutants were identified that had increased sensitivity for the petiole positioning response under low light. One suppressor mutant was identified as a novel allele of the phytochrome B red light receptor, the second is likely to be a mutant of a transcription factor, and the identity of the third candidate suppressor is still not known, though it overexpressed the L2K protein. These candidate suppressors may represent novel modulators of phot1 activity and possible mechanisms for how these candidate suppressors may act on phot1 activity are discussed. In summary, both the biochemical and genetic approaches yielded mutants with increased sensitivity for phot1-mediated responses, enabling a more detailed understanding of how phot1 sensitivity influences its activity and plant growth.
This lays the groundwork for extending the increased sensitivity observed in response to pulses in the photocycle mutants to responses other phot1-mediated responses, and for integrating new models of suppression of phot1 activity into our framework for phot1 activation and signaling.

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Bissiengou, Pulcherie. "Taxonomic assessment of O. furcillata (Oxalidaceae)." Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/3339.

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Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2005.
The family Oxalidaceae has a worldwide distribution, but is most common in tropical and subtropical regions. Oxalis L. is the largest genus of the family comprising ca. 800 of the 900 species. Oxalis species are annual or perennial herbs or rarely subshrubs or trees. The current study assesses on the taxonomic placement of O. furcillata Salter. Currently this species, comprising two varieties, O. furcillata var. furcillata and O. furcillata var. caulescens Salter, is placed in section Foveolatae. Members of this section have endospermous seeds and fleshy leaflets. However, both in terms of leaf morphological and seed characters the two varieties of this species appear to be misplaced within this section. In addition O. furcillata var. caulescens has a unique pollen type, different from both the typical variety and the rest of the section. Both lines of evidence thus suggest that O. furcillata var. caulescens may be misplaced within this section. The present study thus sets out to assess the placement of O. furcillata in general, and the placement of O. furcillata var. caulescens in particular. A multi-disciplinary approach was followed, which included analyses of macro-morphological (including LM and SEM analyses), biogeographical and palynological characters. The variability of quantitative characters was assessed using the STATISTICA 6.0 software package. Leaf dimensions, plant height, bulb length, petiole length and palynology showed sufficient differences between the two taxa to confirm the separate identity of these two varieties as separate species. O. furcillata var. caulescens was thus raised to specific status as O. caulescens (Salter) Bissiengou. The results suggest two different options in terms of the taxonomic placement of the species O. furcillata and O. caulescens. They can either remain in section Foveolatae, best placed near O. senecta and O. densa or may moved to the highly variable section Latifoliolatae. But retaining them within the section Foveolatae appeared to be the better alternative. The correct position will be established both through further morphological analyses and correlation to the trnL-F and ITS sequence-based phylogeny of the southern African members of Oxalis.

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Cardegård, Fanny. "Alléer i Östergötlands län : alléers utbredning och förändring mellan 1868-1877 och idag." Thesis, Högskolan Kristianstad, Fakulteten för naturvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-17946.

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Alléer är ett landskapselement som består av både natur och kultur och som planterats av människan av olika skäl. Sveriges alléer minskar och därför önskar Trafikverket och Riksantikvarieämbetet ta fram ett nationellt underlag för alléer. I Östergötland saknas en sammanställning av alléer under historisk tid därför är studiens syfte att undersöka alléers utbredning och kontinuitet i Östergötland från 1868 fram till idag. Resultatet visade att alléer i länet ökat idag jämfört med perioden 1868–1877. Alléer har störst förekomst i slättbygden. Alléer vid gods- samt bruk hade förändrats minst från perioden 1868–1877 till idag vilket troligen beror på att alléer vid gods och bruk redan var vanliga under perioden 1868–1877. Infartsalléer till gårdar har ökat i bygderna sedan perioden 1868–1877 vilket kan kopplas till skiftesreformerna som förändrade landskapet under slutet av 1800-talet och gav upphov till alléplanteringar i länet. Hos dagens alléer är alléer med blandade trädslag främst förekommande.
Avenues are a landscape element that consist of both nature and culture and that’s been planted by man for various reason. The Swedish avenues reduces because of that the Trafikverket and the Riksantikvarieämbetet wishes to develop a national basis for avenues. In Östergötland there is no compilation of avenues in historical time because of that the purpose of the study is to examine avenues spread and continuity in Östergötland from 1868 until today. Avenues has the greatest occurence in the flat country. Avenues belonging to manor or factory had changed least from the period 1868-1877 until today which is probably due to avenues belonging to manor or factory already was common under the period 1868-1877. Approach avenues leading to farms has increased in the districts since 1868-1877 which can be linked to the agriculture shiftreform that changed the landscape in the late 19th century and gave rise to avenue plantings in the county. Today’sk avenues are avenues witch mixed tree species uppermost occurring.

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Grau, Andres Roger. "Drought and fuel structure controls on fire severity : effects on post-fire vegetation and soil carbon dynamics." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/7929/.

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Calluna-dominated habitats, including dry heaths and peat bogs, provide important ecosystem services such as biodiversity, soil carbon stores and water supply. Climate change projections estimate drier conditions throughout their range, which could lead to increased wildfire activity. Such altered fire regime could induce a fundamental change to the ecology of Calluna moorlands and increase carbon emissions from their carbon-rich soils. The aim of this research was to understand how ecosystem response varies in relation to increased fire severity in Calluna heathlands and peat bogs. I completed experimental fires at two sites in Scotland, a dry heath and a raised bog, where I manipulated pre-fire fuel structure and fuel moisture content to achieve a gradient of fire severity and investigated the subsequent effect on post-fire vegetation regeneration and soil carbon dynamics. I found that drought increased fire severity in terms of ground fuel consumption and soil heating through increased flammability of the moss and litter layer. Substantially higher fire-induced ground heating was recorded when this layer ignited. When consumption of the moss and litter layer was extensive, post-fire soil thermal dynamics were altered and diurnal and seasonal thermal variation was higher, resulting in warmer soils that may lead to higher soil carbon emissions. Fire effects (ground fuel consumption, ground heating, changes in post-fire soil thermal dynamics) were much stronger at the dry heath than at the raised bog, likely due to ecohydrological differences between sites, i.e. thicker moss layer and deeper, wetter soil at the raised bog. For example, average fire-induced maximum temperatures at the soil surface at the dry heath increased from 31 degree C to 189 C due to drought, but at the raised bog they increased from 10 C to 15 C. Post-fire vegetation community composition varied in relation to the gradient of fire severity at the dry heath. Higher fire severity increased abundance of dominant ericoid species (Calluna vulgaris, Erica cinerea and Erica tetralix ) through improved substrate conditions (consumption of the moss and litter layer leading to bare soil), despite the fact that higher fire-induced soil heating hindered their regeneration. Short-term soil carbon emissions increased after burning due to a greater reduction in photosynthesis than in ecosystem respiration. Methane fluxes were negligible at the dry heath, but increased after burning at the raised bog, especially in warmer conditions. Generally, higher fire severity had little effect on soil carbon dynamics (ecosystem respiration, net ecosystem exhange, methane flux and dissolved organic carbon concentration), but higher autumn emission after higher fire severity at the dry heath and the important control of plant functional type cover suggest differences may become apparent in the longer term. This research advances our understanding of how an altered fire regime with higher fire severity could alter ecosystem functioning in Calluna moorlands and impact on its conservation value and belowground carbon stores. The work presented here can be useful to managers using burning as a land management tool, or who need to plan for wildfire occurrence in these fire-prone habitats, to inform strategies to accomplish a range of objectives, including conservation, protection of carbon stores and recreation, and to researchers interested in environmental change in Calluna moorlands. This research was funded by the University of Glasgow with support from the Centre for Ecology and Hydrology, the Ohio State University and Glen Tanar Estate.

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Betts, C. J. "Synecological factors and processes of Calluna-lichen sub-communities at Hartlebury Common." Thesis, University of Worcester, 1990. http://eprints.worc.ac.uk/7125/.

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Hacking, Rachel. "The plant communities of disused railway ballast in Great Britain." Thesis, Edge Hill University, 2014. http://repository.edgehill.ac.uk/7990/.

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Disused railway lines make excellent vehicles to study ecological processes being linear, of fixed width, constructed in the same way, with potential vegetation influences such as time since abandonment and climate being easy to discover. Moreover they are rarely studied. Thus the current study fills a gap in the literature. Samples were taken from a total of 176 releves across 35 sites on 22 different railway lines within England and Wales. The communities were analysed using the standard UK phytosociological method, the National Vegetation Classification (NVC). Few similarities were found with published NVC communities. A large number of communities had affinities with MG1 Arrhenatherum elatius grassland but with un-described sub-communities, with ruderal species or wood and scrub species as major components. Similarly, a number of communities had affinities to OV communities but with different constant species. Hence it is difficult to apply the NVC to synanthropic habitats and that there are ruderal communities in existence that are not described in the NVC. A modified Braun-Blanquet approach to analysing the vegetation data was also undertaken. Hierarchical analysis identified seven clusters equating to communities. Species characteristic of each community were identified using Indicator Values, although these species rarely had both high fidelity and exclusivity. The potential contribution of environmental, temporal and edaphic variables to the development of these communities was assessed. This was underpinned by the theoretical question of succession. Is it an ordered progression through to a climax community or is the process much more stochastic ? There is no simple relationship between time since abandonment and any measure of successional progress. However CCA analysis showed that some factors, primarily abiotic, were significantly associated with community composition. Time since abandonment only becomes significant when it is combined with soil factors. This suggests that vegetation composition is not entirely random in these communities.

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Zhang, Ben. "The role of VAMP proteins in K+ channel regulation." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6230/.

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SNARE (soluble N-ethylmaleimide-sensitive factor protein attachment protein receptor) proteins drive vesicle traffic, delivering membrane and cargo to target sites within the cell and at its surface. They contribute to cell homeostasis, morphogenesis and pathogen defense. A subset of SNAREs, including the Arabidopsis SNARE SYP121, are known also to coordinate solute uptake via physical interactions with K+ channels and to moderate their gating at the plasma membrane. R-SNAREs, also known as vesicle-associated membrane proteins (VAMPs), are most commonly associated with trafficking vesicles. In guard cells of Arabidopsis, ABA-dependent stomatal closure was inhibited when the expression of VAMP71 family genes were suppressed by an antisense VAMP711 construct. Such results reveal that VAMPs play an important role in plant response to stress, especially in the regulation of stomatal closure under ABA treatment. Two R-SNAREs, VAMP721 and VAMP722, are known to assemble in SNARE core complexes with SYP121 and with its closest homolog SYP122, which raises the question whether the channel interaction might extend to the R-SNAREs leading to VAMP regulating channel gating. To answer this question, I investigated the interaction between the VAMP7 proteins with KC1 and KAT1 K+ channels by mating based Split-Ubiquitin System (mbSUS) assay, and verified these interactions by ratiometric bimolecular fluorescence complementation (rBiFC) assay. I found VAMP721 and VAMP722, but not VAMP723, interacted with the channels. The selective binding was associated with the VAMP longin domain, notably with Tyr57. What is the effect of the VAMP-K+ channel interaction on transmembrane ion transport and vesicle traffic? I found VAMP721 affected K+ channel gating and suppressed the K+ current within the physiological voltage range by electrophysiological analysis in Xenopus oocytes and in VAMP over-expression wild type Arabidopsis. The effect of VAMP721 on K+ channel regulation was opposite to the action of SYP121 on K+ channel. From localization, interaction and electrophysiological studies, I was able to show that Tyr57 is a key residue required both for VAMP-dependent gating of the K channels and for localization of the VAMPs at the plasma membrane. For vesicle traffic, I found overexpression of full length VAMP721 in Arabidopsis seedlings blocked the secretion of secYFP while coexpressing with KC1 K+ channel rescued the traffic block, demonstrating a potential action of VAMP-K+ channel interaction on secretory traffic. These results add to understanding the interaction between SNARE and K+ channels that link membrane traffic with osmotically active solute transport in the plant.

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Thomson, Catriona E. "Investigation of phototropin blue light receptor function and signalling in arabidopsis." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/170/.

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The global success of plants depends largely on their ability to perceive and respond to light, mainly in two regions of the electromagnetic spectrum. Phytochromes are light sensors for the red and far-red wavelengths of light while cryptochromes, phototropins and members of the ZTL/ADO family respond to blue and UV-A wavelengths of light. Phototropins are UV-A/blue-light receptor kinases found ubiquitously in plants from the unicellular green alga Chalmydomonas reinhardtii through bryophytes and pteridophytes up to angiosperms. The model plant Arabidopsis possesses two phototropins (phot1 and phot2) and is the subject of the work presented in this thesis. The general structure of the phototropin protein comprises a photosensory region at the N-terminal that contains two LOV (light, oxygen and voltage sensing) domains and a C-terminal kinase domain belonging to the large AGC family of protein kinases. The LOV domains form a covalent adduct with the chromophore flavin mononucleotide (FMN) in response to illumination with blue light which in turn leads to structural changes throughout the protein resulting in autophosphorylation of the N-terminal region by the kinase domain. Phototropins function redundantly to mediate a number of physiological responses in planta which serve to promote plant fitness and maximise photosynthetic potential. Phototropism, chloroplast accumulation, blue light-induced stomatal opening, leaf expansion and leaf movements can be induced through the activation of both phot1 and phot2 in response to different intensities of light, with phot1 being more light sensitive than phot2. In addition to the functionally redundant responses, phot1 alone is responsible for destabilisation of certain mRNA transcripts and the rapid inhibition of hypocotyl elongation when etiolated seedlings are transferred to blue light, while phot2 is solely responsible for the high light induced chloroplast avoidance response. While much is known about the mechanisms of light perception by the phototropins at the molecular level, and the responses mediated by them have been well described, little is known about their methods of signalling to induce these physiological responses upon photoactivation by blue light. Therefore, the aims of this study were to identify novel phot-interacting proteins and to investigate the modes of phot1 signalling by structure/function analyses in order to better understand the way phototropins elicit signal transduction to downstream components in order to bring about the responses described above. Initially, a yeast two-hybrid screen was carried out to try to identify immediate interacting partners for phot1. The results of the yeast two-hybrid screen are described in Chapter 3. One hundred and thirty yeast colonies containing putative phot1-interacting proteins were identified from the screen and preliminary characterisation of six of these proteins are described in this chapter. Two of the proteins investigated are members of the ADP-ribosylation family which is involved in the regulation of membrane trafficking. The ARF proteins identified show a blue-light-sensitive interaction with phot1 and also interact with phot2. These proteins are of interest given the subcellular movement of phototropins from the plasma membrane after exposure to blue light. The C-terminal kinase domain of phot1 was found to interact with p-glycoprotein 19 (PGP19), a protein involved in polar auxin transport. The interaction between these proteins is interesting because of the role auxin plays in phot1-mediated responses such as phototropism and leaf expansion, and preliminary characterisation of the interaction in vitro is shown in Chapter 3. The implications of a direct link between phototropins and the proteins involved in auxin transport are discussed. A further two proteins identified from the screen are members of the NPH3/RPT2-Like (NRL) family. RPT2 has already been identified as a phot1-interacting protein and identification of this protein increased confidence in the efficacy of the screen to identify genuine interacting proteins. A novel member of the NRL family, designated NPH3-L, was also identified from the screen. Chapter 4 describes the tissue specific and subcellular localisation of NPH3-L and contains results of preliminary investigations into the function of NPH3-L in planta. 14-3-3λ was identified from the screen using full-length phot1 as bait. A 14-3-3 protein has been shown previously to bind to autophosphorylated phototropin in Vicia faba (Kinoshita et al., 2003). Chapter 5 details the localisation of 14-3-3λ at tissue and subcellular levels and shows that 14-3-3λ binding to plant-derived phot1-GFP is both light dependent and induced by receptor autophosphorylation. Creation of GFP-14-3-3λ overexpressing lines in wild-type and phot1-5phot2-1 backgrounds allowed investigation into the roles that light and phototropins play in regulating the subcellular localisation of 14-3-3λ. It is shown that light-induced movement of 14-3-3λ at the plasma membrane is dependent on the presence of endogenous phototropins. Physiological implications of this interaction are discussed. Finally, in order to determine the modes of phototropin signalling, structure/function studies were carried out by expressing different regions of phot1 in a variety of Arabidopsis backgrounds. The results of the structure/function studies are described in Chapter 6. Known phot1-mediated responses were investigated in the transgenic plants to determine the effects of individual domains of phot1. Particular attention was paid to the role of receptor autophosphorylation in phot1-mediated responses to light. A transgenic line overexpressing the LOV2-kinase region of phot1 demonstrates that phot1 autophosphorylation is not the primary signalling event involved in phot1-mediated responses to light and shows that the truncated version of phot1 is sufficient to complement most phot1-mediated responses. This also shows that the LOV1 domain is dispensable and suggests phot1 may signal through phosphorylation of substrates. Comparisons are drawn between phot1 kinase overexpressing lines and inactive phot1 kinase overexpressing lines. Preliminary observations of a transgenic line overexpressing phot1 in a wild-type background indicate that overexpression of phot1 may alter polar auxin transport. Together these studies provide new insights into possible mechanisms of phot1 signalling and the function of major domains of phot1.

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Kaiserli, Eirini. "Subcellular localisation and functional analysis of UVR8, a UV-B specific signalling component in Arabidopsis." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/57/.

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UV-B is an integral component of the daylight spectrum that regulates plant gene expression and development, but very little is known about how plants perceive UV-B. Although UV-B-induced damage and repair have been extensively investigated, the mechanisms by which UV-B is perceived as a signal, which mediates physiological and protective responses is not yet clearly understood neither in mammals, nor in higher plants. Low fluence rates of UV-B induce the expression of genes involved in UV-protective responses such as flavonoid biosynthesis and promote plant survival in UV-B. The aim of this study is to contribute to the elucidation of the signal transduction events that lead to the acclimation of plants in response to non-damaging levels of UV-B (< 3.5 μmol m-2 s-1). In particular, the characterisation of UVR8 (UV-RESISTANCE LOCUS 8), a UV-B specific signalling component, is carried out at the protein level. The function of UVR8 involves the orchestration of the expression of a range of genes mediating vital UV-protective responses, including those encoding light-regulated transcription factors HY5 and HYH, enzymes involved in the phenylpropanoid pathway, antioxidant and stress proteins (Brown et al., 2005). UVR8 shows 30% sequence identity to the human regulator of chromatin condensation (RCC1) but differs both in activity and function. The phenotype of uvr8 mutant plants is characterised by an increased susceptibility to UV-B and the lack of the UV-B-specific induction of genes involved in UV-protection, such as CHS (encoding the flavonoid biosynthetic enzyme chalcone synthase) and the transcription factor HY5. The UVR8-mediated regulation of transcription in response to UV-B seems to occur via the association of UVR8 with chromatin via histones in the promoter region of HY5 (Brown et al., 2005) and other genes involved in light signalling. In this study, further investigation of the mechanism by which UVR8 acts as a UV-B specific signalling component is performed by employing a number of approaches including: spatial, temporal protein analysis, subcellular localisation studies, structure-function analyses, and the yeast-two-hybrid assay for the identification of UVR8 interacting proteins. To study spatial, temporal and wavelength specific UVR8 protein abundance anti-UVR8 peptide antibodies were generated. Western blot analyses showed that UVR8 is ubiquitously expressed in all plant tissues from the very early stages of development and at every light treatment tested (dark, white light, UV-B). The subcellular localisation of UVR8 analysed by confocal fluorescence microscopy revealed that a fusion of UVR8 with green fluorescent protein (GFP) is localised in the cytoplasm and the nucleus of various plant tissues (leaf, hypocotyl, root, flower) and under various light fluence rates and qualities (white, red, UV-A, UV-B). Interestingly, a treatment of low fluence rates of UV-B led to an increase of GFP-UVR8 protein accumulation in the nucleus, which was confirmed by western blot analysis based on protein fractionation studies in wild-type plants. The wavelength specificity, the kinetics and the fluence-rate sensitivity of GFP-UVR8 nuclear accumulation suggest that this response is UV-B specific, rapid (10 min UV-B) and very sensitive to very low fluence rates of UV-B (0.1 μmol m-2 s-1). Protein synthesis does not seem to be involved in this process, as there is no change in the protein levels before and after a UV-B irradiation. To assess the importance of the presence of UVR8 in the nucleus and the cytoplasm of the plant cell, uvr8-1 transgenic plants were produced expressing either constitutively nuclear localised GFP-UVR8 fused to a nuclear localisation signal (NLS), or cytosolically retained GFP-UVR8 fused to a nuclear export signal (NES). Nuclear exclusion of NES-GFP-UVR8 fusion protein was sustained under most light conditions apart from UV-B, which induced nuclear import of the protein. This indicates that the mechanism involved in the nuclear accumulation of UVR8 can overcome an export signal either by masking it or by simply superseding it. Furthermore, the NES-GFP-UVR8 construct was functional after UV-B treatment, since it rescued the mutant uvr8 phenotype. None of the inhibitor treatments tested (staurosporine, cycloheximide, cantharidin) was successful in blocking the UV-B induced nuclear import of NES-GFP-UVR8, although they impaired the UVR8 regulated induction of CHS expression. Thus, no evidence is presented for a specific protein modification, which could control this response. Constitutive nuclear localisation of NLS-GFP-UVR8 had no effect on the function of the protein according to complementation analyses. Furthermore, no change in localisation, fluorescence intensity or protein abundance was observed in response to white light or after a UV-B irradiation. These results indicate that the constitutive nuclear localisation of UVR8 is not sufficient for constitutive activation of UVR8 regulated gene expression and that a UV-B stimulus is still necessary to trigger these responses. Unfortunately, based on the current data it cannot be concluded whether the UV-B signal perception occurs in the nucleus or in the cytosol of the plant cell. To investigate the structure-function relationship within the UVR8 protein, deletion analyses followed by complementation studies in transgenic plants were performed. More specifically, deletion of the first 23 amino acids at the N-terminus of UVR8 impaired its nuclear accumulation in response to UV-B. Deletion of a 27 amino acid region near the C-terminus had no effect on the UV-B dependent re-localisation of the protein, but abolished UVR8 regulated gene expression. In addition, a highly basic sequence at the extreme C-terminal of UVR8, resembling a putative monopartite nuclear localisation signal, was deleted. Subcellular localisation and complementation analyses suggest that this sequence does not serve as a nuclear localisation signal, it is not involved in the UV-B induced nuclear accumulation and its absence does not affect UVR8 protein function. Chromatin immunoprecipitation assays show that none of the regions deleted is required for chromatin association and none of the deletions affects subcellular localisation in white light. In order to identify interacting partners for UVR8, the yeast-two hybrid system was used. Unfortunately no interacting proteins have been identified, neither from a screen, nor by directed-interaction studies. A different approach could be employed in the future involving size exclusion chromatography of protein extracts from plants in order to establish whether UVR8 functions as part of a complex in vivo.

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16

Litthauer, Suzanne. "Analysing the role of SAL1/PAP retrograde signalling within the circadian system of Arabidopsis thaliana." Thesis, University of Essex, 2017. http://repository.essex.ac.uk/21465/.

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Plants have developed an internal timing mechanism, the circadian system, that serves to synchronise physiological and metabolic functions with daily, predictable cues such as dawn and dusk. This endogenous oscillator is comprised of biochemical and transcriptional rhythms that are entrained by environmental signals, particularly light and temperature, through the action of input pathways. The circadian system provides plants with an adaptive advantage, and techniques that allow in vivo monitoring of circadian rhythms give valuable insights into the components and mechanisms employed by plants to optimally respond to abiotic signals. This study shows that chlorophyll a fluorescence imaging can be used to describe circadian rhythms of PSII operating efficiency (Fq’/Fm’) in the chloroplasts of Arabidopsis thaliana. These circadian rhythms in Fq’/Fm’ are influenced by the well-defined rhythmic transcriptional feedback loops that comprise the central oscillator in the nucleus, and are maintained under constant blue light by the action of phototropin photoreceptors. Using chlorophyll a fluorescence imaging, the chloroplast-localised enzyme SAL1 was identified as impacting circadian oscillations both in chloroplasts and in the nucleus. SAL1 is a redox-sensitive component of the SAL1-PAP-XRN retrograde signalling pathway, and influences nuclear gene expression in response to stress by modulating the levels of its substrate, 3’-phosphoadenosine 5’-phosphate (PAP). PAP accumulates in chloroplasts under abiotic stress and inhibits the activity of 5’→3’ exoribonucleases (XRNs). This study shows that genetically inducing the SAL1-PAP-XRN pathway in plants lacking SAL1 function induces a long circadian period in a blue light-dependent manner. Application of exogenous PAP or osmotic stress lengthens circadian period, and period lengthening correlates with increases in endogenous PAP levels. Furthermore, plants lacking functional XRNs exhibit a similar long circadian period phenotype. The SAL1-PAP-XRN pathway is therefore proposed to regulate nuclear circadian rhythms in response to changes in chloroplast redox poise, and serves as a possible link between molecular timekeeping and abiotic stress response mechanisms.

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17

Battle, Martin W. "Understanding and engineering photoresponses in Arabidopsis thaliana." Thesis, University of Essex, 2018. http://repository.essex.ac.uk/23574/.

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Light is a remarkably versatile and precise tool, the prevalent nature of which has caused it to become a common stimulus in biological processes. Along with metabolic signals derived from photosynthesis, plants have evolved a suite of five known families of photoreceptor proteins which make up photoperception array of the organism. These photoreceptors are the red and far-red light sensitive phytochromes, the blue light sensitive cryptochromes, phototropins and zeitlupe family and the UV-B receptor UVR8. The role of phototropins in the maintenance of circadian rhythms in the chloroplast has been recently identified, suggesting the potential for further involvement of phototropins in the circadian system of Arabidopsis. This study shows that in mutant plants lacking functional phototropins, the lack of phototropin function has little effect upon circadian rhythms of luciferase bioluminescence but is sufficient to induce loss of robustness in rhythms of chlorophyll fluorescence, indicating that phototropins are most likely indirectly involved in the regulation of circadian rhythms via the chloroplast and not directly involved in the regulation of the nuclear circadian clock. No known plant photoreceptors have a peak of absorbance within the green range of the photosynthetically active spectrum. While plants are capable of developing to maturity in the absence of green light, this study examines some of the subtle ways in which plants respond to green light. Via observation of hypocotyl elongation in seedlings lacking specific photoreceptor functions we show that phytochromes and cryptochromes are required to induce de-etiolation in seedlings grown under green light. Additionally, luciferase bioluminescence imaging of mutants lacking cryptochrome function is used to show that cryptochromes are required to maintain circadian rhythms in Arabidopsis under certain green light spectra, although the presence of blue wavelengths within the spectra of many green lights are sufficient to mask this response. Finally, the subtlety of green light responses in plants has provided a non-invasive input for an optogenetic construct which allows for light controlled manipulation of gene expression in planta. In this study, we present the design and engineering of a green light sensitive optogenetic system for use within plants based upon a cyanobacterial photoreceptor. This prototype system is functional in transiently transformed Nicotiana benthamiana leaves but displays significant leakiness and requires further development before its uses can be developed upon. Additionally further development is required in order to better engineer the system for the production of stable transgenic lines in Arabidopsis. The studies presented here seek to define and explore the roles of phototropins and green light within the circadian system and to design and engineer a green light sensitive optogenetic system for use in plants.

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18

Eisenach, Cornelia. "Membrane and ion channel trafficking in stomatal regulation." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/3004/.

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Stomata open in response to light allowing CO2 uptake for photosynthesis and they close in response to abiotic stress, such as drought, to prevent transpirational water loss from the plant. A pair of guard cells surrounds each stoma and stomatal movements depend on K+ fluxes across the guard cell plasma membrane. These fluxes are mediated by inward and outward rectifying K+ channels (K+in and K+out). The SNARE SYP121 was originally identified in association with ion channel regulation in guard cells. SNARE proteins mediate vesicle fusion and facilitate delivery of membrane proteins to target membranes. They are also linked to a variety of physiological responses. In particular, the plasma membrane SNARE SYP121 has been attributed a role in immune response and K+ nutrition. I have used the Arabdopsis loss-of-function mutant syp121 and uncovered a set of mutant phenotypes associated with impaired stomatal opening. In the syp121 mutant stomatal reopening was delayed and incomplete following Ca2+-induced closure, and increase in stomatal transpiration was slowed in the light. Incomplete reopening was rescued by complementation with wild-type SYP121 and was not observed in the syp122 mutant, lacking the homologous gene product. Guard cell K+ in current, necessary for K+ uptake during stomatal reopening, was reduced in syp121 mutant guard cells. Analysis of current gating characteristics suggested an impaired delivery of K+in channels to the plasma membrane, which was consistent with inhibition of stomatal reopening by the trafficking inhibitor Brefeldin A in wild-type plants. Impaired stomatal reopening in the syp121 mutant was phenomenologically similar to a Ca2+-encoded form of ‘programmed closure’ and my results suggest that endocytosis and delayed recycling of K+in channels may underly this phenomenon. Impaired stomatal function manifested in a conditional syp121 mutant growth phenotype dependent on high light and low humidity, characterised by reduced stomatal conductance and photosynthetic CO2 assimilation. My results suggested the necessity for SYP121-dependent K+in channel traffic during stomatal reopening. My results revealed a novel syp121 stomatal phenotype that was linked to K+in channel recycling in guard cells and had consequences for whole-plant water use and biomass production.

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19

Lanier-Shipp, Elizabeth. "Investigating Nature: John Bartram's Evolution as a Man of Science." Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1180703760.

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20

Tiang, Choon Lin. "The role of SYN1 in early Arabidopsis meiosis." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1341/.

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SYN1 is a meiosis-specific Arabidopsis homologue of yeast REC8. REC8 is an important component of the meiotic cohesion complex which maintains cohesion between sister chromatids. Cytological analysis of syn1\(^{-/-}\) has shown chromosome fragmentation at metaphase I. To determine the basis of chromosome fragmentation in the syn1\(^{-/-}\), three double mutants were constructed. I have demonstrated that chromosome fragmentation in syn1 is AtSPO11-1-dependent. Moreover, I have also shown that SYN1 has a role in DSB repair by analysing Atdmc1\(^{-/-}\)/syn1\(^{-/-}\) meiocytes. To investigate this further, immunolocalization studies in wild-type and syn1\(^{-/-}\) were conducted. Distribution of ASY1 and AtZYP1 was affected in syn1\(^{-/-}\). Both proteins appeared as aggregates, developing into an abnormal short linear signal in early prophase I, suggesting that both axis formation and synapsis are compromised. Distribution of the recombination proteins AtRAD51 and AtMLH1 was also aberrant. Localization of SYN1 in wild-type nuclei revealed a continuous signal along the chromosome axes. However, careful inspection revealed that this was accompanied by patches of more intense signals, possibly corresponding to DSB regions. To investigate this further I analysed SYN1 distribution in an Atspo11-1-4\(^{-/-}\) mutant. Whilst faint SYN1 signals were apparent along the axis, no patches of intense signals were visible. Cisplatin-induced DSBs restored AtZYP1 foci in Atspo11-1-4\(^{-/-}\) and also resulted in restoration of intense patches of the SYN1 signals. This is consistent with the recruitment of SYN1 to DSB sites.

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21

Chesney, Sarah Jane. "The Fruits of their Labors: Exploring William Hamilton's Greenhouse Complex and the Rise of American Botany in Early Federal Philadelphia." W&M ScholarWorks, 2014. https://scholarworks.wm.edu/etd/1539624009.

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This dissertation explores the world of early American botany and the transatlantic community of botanical enthusiasts from the perspective of William Hamilton, gentleman botanical collector in late eighteenth and early nineteenth century Philadelphia. Drawing on both existing documentary sources and three seasons of archaeological excavation at The Woodlands, Hamilton's country estate on the west bank of the Schuylkill River, I analyze both the physical requirements of botanical collecting as well as the more nuanced social, cultural, and economic elements of this trade and its early modern participants.;The personal experiences of individual participants in this exchange are often traced through the existing documentary evidence they leave behind, in the form of letters, plant orders, and published works. But this botanical exchange was not just intellectual; it was also physical and material, as both knowledge about plants and the plants themselves were shipped back and forth across the Atlantic Ocean. Exploring the physical and material elements of this trade adds immeasurably to our understanding of the experiences of individual participants by locating them and the items exchanged within the physical spaces of these exchanges themselves. The archaeological investigation of William Hamilton's greenhouse complex at The Woodlands explores the physical and material elements of this trade in one specific site of exchange -- Hamilton's greenhouse complex -- and the ways in which those physical and material elements reflect the experiences of the participants in this transatlantic botanical trade.

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22

Danese, Antonio. "Darwin's contrivances: orchids, evolution and scientific ethics in the philosophy of science of XIX century." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3421859.

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With Orchid book Charles Darwin was able to accurately explain and demonstrate the evolutionary mechanisms underlying flower adaptations and, at the same time, to build a philosophical dimension for natural history. Asa Gray was one of the first to perceive that Orchid book might undermine theological explanations of nature and he described it as "a flank movement on the enemy". Darwin accepted such description implying that he intended to attack natural theology: but there is a debate whether he and Gray had the same "enemy" in mind. I will try to demonstrate that the flank movement was, before than a direct attack on natural theology, a clever and scrupulous attempt to convince scientists of the validity of Darwin's science exposed in Origin. This attempt didn't consist only in the ability to respond to the criticisms of the theologians and philosophers of science. Darwin was able to convince scientists first of all through the methodology imposed on his work: Orchid book was the result of 20 years of a "patient observation" and "accuracy of reasoning", the proposed results were original and showed how advantageous the study of organisms was for natural history under the belief of the modification of species. Among all his post-Origin researches, Orchid book provided a weapon to counteract the destructive and widespread criticisms that the theoretical results of Origin had been obtained. However there are other historical-scientific aspects that we can discover in Orchid book and made the flank movement irreducible to a theological dispute over the fixism and transmutation of species: the place of religion and finalism in the working life of scientists, the meaning of evolution in the professionalization and institutionalization of biology, the emergence of ecology, the historical role of orchids in political and social beliefs of nineteenth-century, the research for practical and theoretical tools for classification, the possibility of observational predictions in botany, the reference to graphic examples to observe the results of natural selection, innovations in agriculture for horticulturists and a new way of interpreting the beauty of nature emancipated from the explanations of natural theology. This leads to a multi-component approach for the clarification of the meaning of the flank movement that makes complementary all the aspects above described. Following this model I will try to show that if we want to give an historical justification for the conversion of botanists to darwinian side of explaining natural history, we have to conceive the flank movement as a mosaic of interactive historical, philosophical and biological components. The core of my argument is that through the choice of orchids as subject for a book in Victorian age and the demonstration that this book allowed new ways for studying classification of species, coevolution, the relationship between function and design in morphology, homologies and natural selection from the perspective of common descent, Darwin managed to convince the scientific community to which he belonged that Origin's generalizations were correct and/or that he never had betrayed the inductive method.

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23

Almalki, Najla Abdullah. "High temperature stress on cereal photosynthesis : a re-evaluation." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/6096/.

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Under natural conditions, crop plants are likely to experience high leaf temperatures that reduce plant growth, reproduction, and photosynthesis, which impact dramatically on crop yield. Some wild plants such as Agave can withstand prolonged periods of Tleaf in excess of 55⁰C but the mechanisms of thermotolerance are unclear at present. To establish whether there is sufficient genetic diversity to be exploited for developing heat tolerant crops, a comparative study was conducted to assess the effects of high leaf temperatures (Tleaf) on two barley lines (C3, Optic and Local) and two maize lines (C4, Sundance and Katumani) that are routinely grown in temperate and sub-tropical regions, respectively, in addition to the obligate C3 plant Yucca filimentosa that is endemic to hot arid habitats. Gas exchange measurements show light saturated CO2 assimilation rates (Asat) and the carboxylation coefficient (the efficiency of CO2 fixation, CO2) were irreversibly suppressed to approximately 20% of their pre-treatment levels immediately after raising Tleaf to 38.0 (± 0.2 ⁰C) for 3 hours in all lines regardless of their origins (temperate or sub- tropical), and this inhibition was not attributed to stomatal closure. In contrast, Y. filimentosa showed a close correspondence between Asat and stomatal conductance (gs) in response to leaf temperatures between 36° to 40°C with a marked suppression immediately after heat stress and rapid full recovery following one hour of release from stress. Above 40°C however, stomata respond differently by opening and increase gs. This pattern suggested the response of stomata in Y. filimentosa is regulated by temperature. There is a general consensus that the primary site of thermal injury to CO2 assimilation is RuBisCO Activase but this is contentious. In this study the effects of high leaf temperatures (Tleaf) on photosynthetic efficiency of barley were re-investigated. Parallel measurements using a range of techniques confirmed that the suppression of Asat was not attributable to Maximum Quantum Efficiency of PSII (ФPSII), or changes in the light harvesting capacity (leaf absorbance, Chla fluorescence excitation spectra), or in vitro electron transport rates. Metabolomics profiling of heat stressed and control leaves showed that carbon flow between Ribose 5-phosphate (Ri5P) and 3-phosphoglycerate (3-PGA) was severely impaired by heat stress, consistent with the assertion that Asat was suppressed by inhibition of RuBisCO activity. Surprisingly, enzyme-linked assays on RuBisCO prepared from leaves exposed to 38.0° (± 0.2°C) for 3 hours showed unequivocally that RuBisCO activity was not affected suggesting the substrates for RuBisCO (CO2 and/or RuBP), rather than RuBisCO activity itself, accounted for the decrease in carbon flow from Ri5P to 3-PGA. These studies also showed that the standard procedures for isolating RuBisCO from cereal leaves lead to a partial re-activation of RuBisCO resulting in false conclusions on the in vivo activation state of the enzyme. The implications of these results are discussed. In intact barley leaves, the suppression in Asat was not reversed by increasing external CO2 (Ca) to 1000 μmol CO2. mol-1 air suggesting chloroplast CO2 levels were not limiting. In vitro assays demonstrated the activities of Ri5P isomerase and phosphoribulose kinase (PRK) were not affected by these heat stress treatments. In contrast, measurements on leaf ATP levels and in vivo electron transport rate (ETR) showed a parallel and dramatic decline (>75%). Post-illumination chlorophyll fluorescence relaxation (light-to-dark transition) was used to assess the magnitude of the proton motive force (pmf) across the thylakoid membrane of control and heat stressed leaves. Heat stress increased the relaxation half time (t½) from 45 to 180 seconds suggesting a decrease in proton conductance through the ATP synthase, and thus a decrease in leaf ATP levels1. Taken together these results suggest high leaf temperatures lead to a decrease in chloroplast ATP levels and this suppresses the synthesis of Ribulose 1,5-Bisphosphate by the C3 Cycle; carbon flow through RuBisCO is impaired and thus whole leaf photosynthesis rates decline severely.

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24

Velanis, Christos N. "Regulation of transcription by Ultraviolet-B radiation in Arabidopsis thaliana." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6204/.

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Plants are sessile photo-autotrophic organisms and need to adapt constantly to a dynamic environment. Light is of utmost importance for plants to be able to monitor their surroundings. Ultraviolet-B radiation (UV-B; 280-315 nm) is an intrinsic part of sunlight and, depending on the wavelength and the fluence rate, it may be a stressful signal or an “informational” one. The so called photomorphogenic responses of plants to UV-B are largely mediated by the UV-B specific photoreceptor UV RESISTANCE LOCUS 8 (UVR8), which “senses” UV-B via a tryptophan based mechanism. UVR8 is localised in the cytoplasm and the nucleus mainly as a homodimer. Upon UV-B irradiation it splits to its monomers and accumulates in the nucleus where it has been found to interact with the E3 Ubiquitin ligase COP1. In the nucleus UVR8 has been shown to associate with chromatin on loci of UV-B responsive genes, including that encoding for the bZIP transcription factor (TF) ELONGATED HYPOCOTYL 5 (HY5), a key effector of UVR8-dependent signalling pathways. The binding of UVR8 to chromatin appears to take place via interaction with histones (H2B in particular) rather than DNA itself. However, this association with chromatin seems not to be UV-B specific. The above data suggest a mechanistic basis for an assumed function of UVR8 in the regulation transcription. It seems likely that UVR8 interacts with other proteins associated with chromatin to promote remodelling and/or recruits/activates TFs which in turn stimulate transcription of its target genes. The main objective of this study was to address the above working hypothesis.

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25

Silva, Patrícia Gomes Pinheiro da [UNESP]. "O ensino da botânica no nível fundamental: um enfoque nos procedimentos metodológicos." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/102000.

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Made available in DSpace on 2014-06-11T19:31:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-03-28Bitstream added on 2014-06-13T20:02:40Z : No. of bitstreams: 1 silva_pgp_dr_bauru.pdf: 1443273 bytes, checksum: e9c4606959d320c45930b364c5b1c3ad (MD5)
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São freqüentes os textos que consideram que a botãnica apresenta grande dificuldade no seu processo de ensino e aprendizagem, gerando pouco interesse e baixo rendimento. Mas, por quê? Quais situações contribuem para reforçar esta afirmação? A partir de uma revisão teórica e histórica sobre o desenvolvimento do estudo dos vegetais, é possível dizer que uma delas seria a falta de atualização do professor em relação ao conhecimento botânico, cada vez mais específico. Outra situação, conseqüentemente, seria a forma como a botânica vem sendo ensinada: muito teórica, desestimulante, fundamentada na reprodução, repetição e fragmentação e distante da realidade dos alunos e dos problemas ambientais atuais. Percebe-se, enfim, a questão metodológica como central no processo de ensino e aprendizagem de botânica, dificultando, o entendimento e criando aversões quando não adequada. Segundo estudos recentes, é importante que os alunos tenham contato com os vegetais na natureza, aproximando-se do ambiente natural.
Many papers hold the view that botany poses great challenge in its teaching and learning process, arising little interest and resulting in poor productivity. What factors account for this? Based on a historical and theoretical review on the development of the study of plants, it is possible to say that one of these factors is the lack of teachers with an updated Knowledge in this increasingly specific field. Another factor is the method applied in the teaching/learning process: too theoretical, unexciting, based on reproduction, repetition and fragmentation, distant from tody's reality and environmental problems. This inadequate method makes difficult for students to understand Botany, in some cases leading to aversion. Therefore, the methodological matter becomes the center of debate concerning the theaching/learning process of the study of plants. According to recent research, it is essential that students come into contact with plants within their natural environment.

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26

Gehl, Bernadette. "Functional and molecular characterisation of two stomatin-like proteins from Arabidopsis thaliana." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/640/.

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Stomatins belong to the band-7 (or SPFH domain) family (short for Stomatin, Prohibitin, Flotillin HflC/K) of diverse membrane proteins. This protein family is evolutionary conserved with members found in all sequenced eukaryotes and in most prokaryotes. Band-7 family proteins have the ability to oligomerise and generally aid in the assembly and regulation of large membrane-bound protein complexes. In animals, stomatins have been demonstrated to regulate ion channels by direct protein interactions. Additionally, they localise to membrane microdomains where they actively contribute to their assembly by binding sterols, and they also associate with the actin cytoskeleton. The Arabidopsis genome encodes for two structurally similar stomatin-like proteins that are functionally completely unknown yet. They will be referred to as AtSlp1 (for Arabidopsis thaliana stomatin-like protein) and AtSlp2. The aim of this thesis was to provide a detailed characterisation of these two genes on a molecular and functional level. Both proteins are expressed ubiquitously throughout plant development, but they accumulate at particularly high levels in pollen and other metabolically active cells. Phylogenetic analysis reveals that AtSlps are homologous to stomatin-like proteins of type 2. Amongst these, the human stomatin-like protein 2 (HsSlp2) is localised to mitochondria where it participates in large membrane-bound protein complexes and is also involved in the proliferation of cancer cells. Evidence is provided here that demonstrates mitochondrial localisation of both Arabidopsis Slp proteins in vitro and in vivo. On a functional level, mitochondria from an slp1 knockout mutant plant have a decreased mitochondrial membrane potential and increased oxygen consumption rates. This is interpreted as a defect in coupling efficiency and an impairment of the mitochondrial inner membrane integrity. This defect results in a variety of other growth phenotypes that are related to metabolically active tissues and cell types. Knockout plants are delayed in overall growth of shoots and roots and have decreased seed germination rates. Additionally, these plants are less resistant to conditions of high salinity and are less fertile. Overexpression of a protein acting as a putative dominant-negative Slp fragment results in plants with a dwarf phenotype and early onset of leaf senescence. This phenotype correlates with increased levels of reactive oxygen species and altered organelle ultrastructure. Guard cells from these plants in particular have enlarged chloroplasts and are impaired in transpirational control. It is concluded that also in plants, stomatins act together with other band-7 family proteins as parts of large protein complexes that have regulatory roles important for development and stress responses. Their main role is probably to provide membrane scaffolds that affect mitochondrial function and morphology during cell division and in situations of mitochondrial stress.

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27

Hoebe, Petrus Nicolaas. "Evolutionary dynamics of mating systems in populations of North American Arabidopsis lyrata." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/1405/.

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Plants can vary in their mating systems from completely inbreeding to completely outcrossing, with intermediate forms referred to as mixed mating systems. Arabidopsis lyrata is a strongly outcrossing perennial due to a sporophytic self incompatibility (SI) system. The species occurs in temperate regions of the Northern hemisphere where in Europe its SI system is fully working but around the Great Lakes of North America some populations of A. lyrata show a breakdown in SI. Consequently these North American populations are inbreeding or have a mixed mating system next to outcrossing populations with a working SI system. In this thesis I used North American A. lyrata to investigate the evolutionary consequences involving variation in mating systems. First of all I was interested in the time that populations had been isolated from each other in the past that could explain differences in mating systems. In order to determine whether populations experienced a breakdown of SI independently or whether this originated from a single event I used chloroplast DNA (cpDNA) markers to reveal deep phylogeny and microsatellite markers to determine recent population genetic patterns. The results showed a loss of SI in populations from all three detected cpDNA haplotypes. Microsatellite data showed that predominantly inbreeding populations sharing one of these haplotypes showed high levels of homozygosity and that in all three haplotype lineages self-compatible individuals always had reduced heterozygosity compared to self-incompatible individuals. The data further showed that there had likely been at least two independent postglacial colonization routes to the north of the great lakes. This was consistent with phylogeographic studies of other organisms with limited dispersal such as reptiles and amphibians. The next question was the role of inbreeding depression in the loss of SI. Inbreeding depression is defined as the decline of fitness after an inbreeding event. Inbreeding causes an increase in homozygosity that exposes recessive deleterious mutations, which would normally be sheltered in a heterozygous state, and causes a fitness decline. Individuals experiencing a loss of SI will have higher inbreeding levels and can result in inbreeding depression, which is thought to maintain the SI system. To gain more insight into the role of inbreeding depression in the shift from self-incompatibility to self-compatibility, I conducted an experiment in which I created outcrossed and selfed offspring from self-compatible and self-incompatible mothers from populations with different outcrossing histories. I monitored the offspring for early- and late acting fitness traits like germination rate, growth and time to flowering. I found inbreeding depression in only one late acting fitness trait, the increase in leaves 5 weeks after germination, to be significantly higher for self-incompatible than self-compatible individuals. I also conducted a regression analysis where relative fitness (the ratio of the fitness trait values of selfed and outcrossed offspring) per mother was regressed against population heterozygosity and found a significantly negative regression. This result suggested that individuals from a population with a relatively high heterozygosity suffered more from inbreeding depression than individuals from populations with a relatively low heterozygosity. This indicated that the history of outcrossing of a population, or purging, played an important role in the shift from outcrossing to inbreeding. The detection of inbreeding depression could not be evident by only looking at life history traits under greenhouse conditions. But stressful environmental conditions like a pathogen infection could magnify inbreeding depression. I would expect that predominantly outcrossing populations would have a higher heterozygosity than predominantly inbreeding populations and therefore be able to show a higher fitness when exposed to a pathogen. To test this hypothesis I used four outcrossing and four inbreeding populations, which I infected with the crucifer pathogen Albugo candida and measured relative growth rates (RGR) and monitored resistance rates. The results showed that there were three infection phenotypes: resistant (no signs of infection), partially resistant (only the initially infected parts showed symptoms) and susceptible (symptoms present on the whole plant). The inbreeding populations showed a bimodal distribution of resistance as two populations showed a high rate of resistance and two showed a low rate of resistance. The outcrossing populations showed a much more uniform distribution of resistant individuals with a higher rate of partially infected individuals across populations than inbreeding populations. Resistant and partially resistant individuals did not differ significantly in their RGR from each other but both had a significantly lower RGR than the untreated control group and a significantly higher RGR than the susceptible individuals. This suggested a cost of resistance that was lower than a cost of being susceptible in the presence of a pathogen. There was no effect of mating system on RGR, which was primarily caused by the fact that two inbreeding populations contained a high amount of resistant individuals and an outcrossing population that showed a very low amount of partially resistant and resistant individuals. The difference in resistance to A. candida in A. lyrata differed much more between inbreeding than between outcrossing populations. This suggested that alleles responsible for resistance were concentrated in homozygous form in inbreeding populations and both homozygous and heterozygous form in outcrossing populations. This would mean that mating system plays a role in susceptibility, as resistance genes would be concentrated in certain individuals in inbreeding populations as opposed to a more modal distribution in outcrossing populations. A shift in mating system often has an effect on floral traits, as there is a lack of necessity to attract pollinators. I wanted to test whether these changes were apparent in A. lyrata by comparing pollinator attractants and sexual floral traits between strongly outcrossing and strongly inbreeding populations. I hypothesized that individuals depending on pollinators for outcrossing would show a higher emission of volatiles and floral traits that had evolved to optimize pollen transmission to conspecifics. Autonomously selfing individuals would be independent of pollinators so should show a reduced volatile emission pattern, a floral trait composition that evolved to transmit pollen to their own stigma, and a reduction in floral display compared to outcrossers. My results showed a somewhat contradicting pattern as self-compatible individuals showed higher volatile emission than self-incompatible individuals but self-incompatible individuals showed larger petal size than self-compatible individuals. Pistil height and stamen length were strongly correlated but petal size seemed to co-vary relatively independent from pistil and stamen length. I found no effect of mating system on the evolvement of floral traits to optimize pollen to the stigma and contradicting patterns for pollinator attractant traits. Due to low sample sizes this study turned out to be a pilot study for further research so the results in this study were not conclusive at this stage. Finally I conclude that SI has been lost independently several times and the low observed genetic load in the North American populations compared to the European populations could be responsible for that. There have probably been two independent colonization routes to the North of the Great Lakes following the last glaciation in which a Northern distributed cpDNA haplotype lineage seems to have a lower frequency of SC individuals than a southern cpDNA haplotype lineage.

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28

Cross, Adam D. P. "The influence of seabird-derived nutrients on island food-webs." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/6312/.

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There is an increasing understanding of the influence seabirds have on island food webs globally, which often arises from the trans-boundary input of nutrients. Seabird-derived nutrients, primarily in the form of guano, can have significant effects on island communities by increasing primary productivity and then indirectly influencing other species. However, there are few studies looking at how the influence of seabirds permeates island food webs to higher trophic levels, in particular within the United Kingdom, which holds globally significant populations of seabirds. To understand the extent to which seabirds influence islands, the size of the seabird population must be first reliably determined. With an increasing seabird population size and density the effects of seabirds on land increases concomitantly. The Atlantic puffin Fratercula arctica is a difficult species to reliably monitor, given its underground presence from the use of burrows and its notoriously erratic attendance at colonies. This study looks firstly at a novel method to monitor the Atlantic puffin using time-lapse photography. Time-lapse photography provides a way to derive an estimate of population size from counts of individuals, by repeated photographs across a period of time with relatively low cost and from areas normally considered inaccessible. The results showed there was a significant and positive relationship between the maximum numbers of Atlantic puffins observed and the size of the population; further work is required though to reduce the error associated with population size estimates. Data from high temporal resolution time-lapse photography shows how the attendance of Atlantic puffins at the colony varies over different temporal scales. Given the variability in sampling intensity the study stresses the need for standardised sampling intensity with the use of photography to monitor Atlantic puffins. Secondly, this study showed how the presence of two seabird species, the Atlantic puffin and the great skua Stercorarius skua, alters island food webs. These seabird species are likely to change plant community diversity, relative to areas without seabirds. The chemical concentration of grasses inside seabird colonies was also altered: grasses had significantly higher concentrations of nitrogen and also had higher values of δ15N, relative to areas without seabirds. These chemical alterations suggest that nutrients from seabirds are incorporated into local vegetation. Furthermore, samples of hair from rabbits and sheep found within puffin colonies also had significantly higher values of δ15N, suggesting that nutrients travel from seabirds into secondary consumers, via ornithogenic forage. An additional study on the transfer of nutrients within island food webs showed how ornithogenic nutrients deposited on an island in the Baltic Sea were incorporated into house martins, via aquatic insects. These studies, along with an understanding of seabird population size, suggest that the impact of seabirds on island food webs may be considerable and have large consequences for island conservation and management.

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Smith, Ross L. "Invasive alien plant species of The Bahamas and biodiversity management." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1275062320.

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30

Hillethan, Morgan. "Smycket av ett biologiskt kulturarv eller en utdöende epok? : en återinventering av hamlade träd i nordöstra Skåne 2019." Thesis, Högskolan Kristianstad, Fakulteten för naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-19794.

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Forskning och studier om hamlade träd och lövängar har varit något begränsad p.g.a. att de spår som syns i våra marker endast hyser ett fåtal rester. Förmodligen har landskapet varit rikt på hamlade träd. Under en inventering som pågick mellan 2004–2007 i nordöstra Skåne lokaliserades individer med hamlingsspår samt lövängsrester. Med den som grundmaterial genomfördes en inventering av fyra utvalda lokaler, varav två har ett formellt skydd i form av naturreservat och kulturreservat samt två utan skydd. Samma metod användes. Inventeringen visar att hamling och nyhamling av träd har ökat, främst på de lokaler som har skydd. Dessa lokaler har dessutom en skötselplan som gynnar hävd vilket passar individer med hamlingsspår. Resurser i form av medel och kunskap borde förläggas inom de områden där hamlade träd har störst chans att leva kvar. Reservat ger den möjlighet som ett långsiktigt bevarandearbete kräver, med en skötsel som gynnar de hamlade individerna, framhäver nyhamling samt det biologiska kulturarvet.

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31

Jimenez, Ricardo A. "Evaluation of Fomesafen for Broadleaf Weed Control, In Soybeans (Glycine Max)." TopSCHOLAR®, 1988. http://digitalcommons.wku.edu/theses/1711.

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The lack of effective broadleaf weed control represents one of the major factors having detrimental effects on growth and yield of soybeans. Broadleaf weeds are a serious threat to soybean growers in the southeastern United States. A broad range of herbicides is being used in an effort to control broadleaf weeds in soybeans, and research is still being conducted to find new herbicides that can best work for this purpose. This study involved the use of one these herbicides. It was fomesafen, 5-[2-chloro-4-trifluromethyl) phenoxy]-N-(methyl-sulfonyl)-2-nitrobenzamide, which controls a broad spectrum of broadleaf weeds in soybeans. The experiment was conducted in the summers of 1987 and 1988. Broadleaf weed control treatments with fomesafen at rates at 0.07, 0.14, 0.28, and 0.35 kg ai/ha in single early postemergence and late postemergence applications were evaluated using the herbicide with a nonionic surfactant at 0.25% and 0.50% of the solution. All treatments were compared with a check which did not receive herbicide application. Among the most common broadleaf weeds found in the area under study during the summer of 1987 were morningglories (Ipomoea spp), redroot pigweed (Amaranthus retroflexus L.), jimsonweed (Datura stramonium L.), common lambsquarters (Chenopodium album L.), carpetweed (Moliugo verticillata L.), and prickly sida (Sida spinose L.), For the summer of 1988 the most prevalent broadleaf weeds were morningglories, horsenettle (Solanum carolinense L.), horseweed [Conyza canadensis (L.), Cronq.], and prickly sida. The results of the experiment showed no significant differences between early postemergence and late postemergence treatments. There were no significant differences in broadleaf weed control in treatments which received 0.14, 0.28 and 0.35 kg ai/ha of fomesafen for either 1987 or 1988. Poor broadleaf weed control resulted with the application of fomesafen at its lowest rate (0.07 kg ai/ha). No significant differences were found in broadleaf weed control between concentration of 0.25% and 0.50% of the nonionic surfactant added to fomesafen. Statistically significant yield variation did occur among treatments in 1987. No significant differences in yields were found between any of the herbicide treatments in 1988. Soybean yields were significantly higher in 1988 than in 1987.

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Scales, J. C. "Improving the thermal tolerance of photosynthesis in wheat." Thesis, University of Essex, 2015. http://repository.essex.ac.uk/15358/.

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Wheat yields need to rise to meet growing demands due to population growth and changing diets. Additionally, the resilience of crop yields to climate change and rising temperatures needs to be improved. Inhibition of photosynthesis under sub-optimal environmental conditions decreases carbon fixation, reducing crop yields. Heat stress inhibits photosynthesis, in part due to a decrease in the activation state of Rubisco. Rubisco activase (Rca) is required to restore and maintain the catalytic activity of Rubisco. Rca has a relatively low temperature optimum; improving its thermal tolerance would maintain Rubisco activity and enhance photosynthesis at higher temperatures, with predicted positive impacts on grain yields under moderate heat stress. Two approaches were taken to improve the thermal tolerance of Rca in wheat. Firstly, natural variation in the thermal tolerance of Rca in wheat was investigated. Cultivars exhibiting differences in their photosynthetic performance were identified, but the complexity in breeding for increased thermal tolerance was highlighted, with both advantageous and disadvantageous characteristics being identified. The second approach was to introduce the more thermally stable Rca from cotton into wheat in an attempt to broaden the range of temperatures at which photosynthesis operates. Transgenic plants were produced but the cotton Rca protein was undetectable in the wheat lines investigated. Two genes encoding Rca in wheat were identified; one gene is alternatively spliced to produce α and β isoforms. Virus-Induced Gene Silencing of the Rca isoforms in wheat indicated that the Rca genes in wheat may be co-regulated. A non-radioactive activity assay was developed for use in Rubisco and Rca research, allowing high-throughput of samples and avoiding the difficulties some labs may have in completing radioactive assays. The information gained in this study will guide future approaches to optimise the thermal stability of Rca and generate temperature-resilient crops.

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Kellermeier, Fabian. "Environmental genetics of root system architecture." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4663/.

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The root system is the plant’s principal organ for water and mineral nutrient supply. Root growth follows an endogenous, developmental programme. Yet, this programme can be modulated by external cues which makes root system architecture (RSA), the spatial configuration of all root parts, a highly plastic trait. Presence or absence of nutrients such as nitrate (N), phosphate (P), potassium (K) and sulphate (S) serve as environmental signals to which a plant responds with targeted proliferation or restriction of main or lateral root growth. In turn, RSA serves as a quantitative reporter system of nutrient starvation responses and can therefore be used to study nutrient sensing and signalling mechanisms. In this study, I have analysed root architectural responses of various Arabidopsis thaliana genotypes (wildtype, mutants and natural accessions) to single and multiple nutrient deficiency treatments. A comprehensive analysis of combinatorial N, P, K an S supply allowed me to dissect the effect of individual nutrients on individual root parameters. It also highlighted the existence of interactive effects arising from simultaneous environmental stimuli. Quantification of appropriate RSA parameters allowed for targeted testing of known regulatory genes in specific nutritional settings. This revealed, for example, a novel role for CIPK23, AKT1 and NRT1.1 in integrating K and N effects on higher order lateral root branching and main root angle. A significant contribution to phenotypic variation also arose from P*K interactions. I could show that the iron (Fe) concentration in the external medium is an important driving force of RSA responses to low-P and low-K. In fact, P and K deprivation caused Fe accumulation in distinct parts of the root system, as demonstrated by Fe staining and synchrotron X-Ray fluorescence. Again, selected K, P and Fe transport and signalling mutants were tested for aberrant low-K and/or low-P phenotypes. Most notably, the two paralogous ER-localised multicopper oxidases LPR1 and LPR2 emerged as important signalling components of P and K deprivation, potentially integrating Fe homeostasis with meristematic activity under these conditions. In addition to the targeted characterisation of specific genotype-environment interactions, I investigated novel RSA responses to low-K via a non-targeted approach based on natural variation. A morphological gradient spanned the entire genotype set, linking two extreme strategies of low-K responses. Strategy I accessions responded to low-K with a moderate reduction of main root growth but a severe restriction of lateral root elongation. In contrast, strategy II genotypes ceded main root growth in favour of lateral root proliferation. The genetic basis of these low-K responses was then subsequently mapped onto the A. thaliana genome via quantitative trait loci (QTL) analysis using recombinant inbred lines derived from parental accessions that either adopt strategy I (Col-0) or II (Ct-1). In sum, this study addresses the question how plants incorporate environmental signals to modulate developmental programmes that underly RSA formation. I present evidence for novel phenotypic responses to nutrient deprivation and for novel genetic regulators involved in nutrient signalling and crosstalk.

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Murphy, Stephen J. "Community Assembly and Dynamics of the Forests of Powdermill Nature Reserve (Rector, PA)." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu153200426920788.

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35

Hung, Kuang-Chi. "Finding Patterns in Nature: Asa Gray's Plant Geography and Collecting Networks (1830s-1860s)." Thesis, Harvard University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3600183.

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It is well known that American botanist Asa Gray's 1859 paper on the floristic similarities between Japan and the United States was among the earliest applications of Charles Darwin's evolutionary theory in plant geography. Commonly known as Gray's "disjunction thesis," Gray's diagnosis of that previously inexplicable pattern not only provoked his famous debate with Louis Agassiz but also secured his role as the foremost advocate of Darwin and Darwinism in the United States. Making use of previously unknown archival materials, this dissertation examines the making of Gray's disjunction thesis and its relation to his collecting networks. I first point out that, as far back as the 1840s, Gray had identified remarkable "analogies" between the flora of East Asia and that of North America. By analyzing Gray and his contemporaries' "free and liberal exchange of specimens," I argue that Gray at the time was convinced that "a particular plan" existed in nature, and he considered that the floristic similarities between Japan and eastern North America manifested this plan. In the 1850s, when Gray applied himself to enumerating collections brought back by professional collectors supported by the subscription system and appointed in governmental surveying expeditions, his view of nature was then replaced by one that regarded the flora as merely "a catalogue of species." I argue that it was by undertaking the manual labor of cataloging species and by charging subscription fees for catalogued species that Gray established his status as a metropolitan botanist and as the "mint" that produced species as a currency for transactions in botanical communities. Finally, I examine the Gray-Darwin correspondence in the 1850s and the expedition that brought Gray's collector to Japan. I argue that Gray's thesis cannot be considered Darwinian as historians of science have long understood the term, and that its conception was part of the United States' scientific imperialism in East Asia. In light of recent studies focusing on the history of field sciences, this dissertation urges that a close examination of a biogeographical discovery like Gray's thesis is impossible without considering the institutional, cultural, and material aspects that tie the closets of naturalists to the field destinations of collectors.

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36

Sandor, Daniel S. "Cultivar, Mowing Height, and Herbicide Effects on Bermudagrass, Cynodon Dactylon [L.] Pers., Suppression in Tall Fescue, Schedonorus Arundinaceus [Schreb.] Dumort., Nom. Cons." TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1270.

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In the fall of 2011, a study was initiated at the Western Kentucky University Farm in Bowling Green, Kentucky on a Crider silt loam (Typic Paleudalf). The objective of this study was to determine cultivar, mowing height, and herbicide effects on bermudagrass, Cynodon dactylon [L.] Pers., suppression in tall fescue, Schedonorus arundinaceus [Schreb.] Dumort., nom. cons. The experimental design was a split plot design with whole plots consisting of varying mowing heights and split plots consisting of different herbicide treatments with three replications. Two separate experiments were conducted. The tall fescue variety ‘KY 31’ was utilized for one study and the turf type cultivar ‘Bullseye’ was utilized in the other. In the fall of 2011, glyphosate (Roundup Pro) was applied to selected plots at the rate of 0.36 kg ae/ha. ‘KY 31’ and ‘Bullseye’ tall fescues were sown into an existing mixed stand of common and hybrid bermudagrass at 342 kg pls/ha. Mowing heights were maintained at 7.62 cm, 10.16 cm, and 12.70 cm. In the spring of 2012, treatments containing fenoxaprop (Acclaim Extra), mesotrione (Tenacity), and fluazifop (Fusilade II) were applied to selected plots at the rates of 0.07 kg ai/ha, 0.48 kg ai/ha, and 0.24 kg ai/ha respectively. A non-ionic surfactant at 0.25% (v/v) was utilized in treatments containing mesotrione and fluazifop. Three weeks later these treatments were applied a second time. Data were collected visually on turf quality, tall fescue cover, broadleaf weed cover, and bermudagrass cover. The study was repeated in 2012 – 2013. Fluazifop and glyphosate + fluazifop resulted in significantly lower turf quality than all other treatments up until ten weeks after initial treatment. Treatments containing fluazifop significantly reduced tall fescue cover but also significantly suppressed bermudagrass cover the greatest. However, these treatments also resulted in the greatest amount of broadleaf weed cover. High mowing heights may play a role in achieving high turf quality ratings and better broadleaf weed and bermudagrass suppression in forage type tall fescue than in turf type tall fescue.

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37

Obone, Charline. "The systematic significance of the fruit and seed morphology and anatomy in selected Oxalis L. (Oxalidaceae) species." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1147.

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38

Albhilal, Waleed Sulaiman. "The Arabidopsis thaliana heat shock transcription factor A1b transcriptional regulatory network." Thesis, University of Essex, 2015. http://repository.essex.ac.uk/15732/.

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Plants as sessile organisms have adapted highly sophisticated cellular processes to cope with environmental stress conditions, which include the initiation of complex transcriptional regulatory circuits. The heat shock transcription factors (HSFs) have been shown to be central regulators of plant responses to abiotic and biotic stress conditions. However, the extremely high multiplicity in plant HSF families compared to those of other kingdoms and their unique expression patterns and structures suggest that some of them might have evolved to become major regulators of other non-stress related processes. Arabidopsis thaliana HSFA1b (AtHSFA1b) has been shown to be a major regulator of various forms of plant responses to abiotic and biotic stresses. However, it has also been suggested that overexpression of AtHSFA1b results in a subtle developmental effect in Arabidopsis thaliana and Brassica napus in the form of increased seed yield and harvest index. Through genome-wide mapping of the AtHSFA1b binding profile in the Arabidopsis thaliana genome, monitoring changes in the AtHSFA1b-regulated-transcriptome, and functional analysis of AtHSFA1b in Saccharomyces cerevisiae under non-stress and heat stress conditions, this study provides evidence of the association of AtHSFA1b with plant general developmental processes. Furthermore, the outcome of this research shows that AtHSFA1b controls a transcriptional regulatory network operating in a hierarchical manner. However, in an agreement with a previously suggested model, the results from this study demonstrate that the involvement of AtHSFA1b in the regulation of heat stress response in Arabidopsis thaliana is possibly limited to the immediate and very early phases of heat stress response which also results in a collapse in its transcriptional network which seems to be accompanied by a general shutdown in plant growth and development.

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Silva, Patrícia Gomes Pinheiro da. "O ensino da botânica no nível fundamental : um enfoque nos procedimentos metodológicos /." Bauru : [s.n.], 2008. http://hdl.handle.net/11449/102000.

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Orientador: Osmar Cavassan
Banca: Elenice Moura Varanda
Banca: Jandira Liria Biscalquini Talamoni
Banca: Renata Carmo de Oliveira
Banca: Fernando Bastos
Resumo: São freqüentes os textos que consideram que a botãnica apresenta grande dificuldade no seu processo de ensino e aprendizagem, gerando pouco interesse e baixo rendimento. Mas, por quê? Quais situações contribuem para reforçar esta afirmação? A partir de uma revisão teórica e histórica sobre o desenvolvimento do estudo dos vegetais, é possível dizer que uma delas seria a falta de atualização do professor em relação ao conhecimento botânico, cada vez mais específico. Outra situação, conseqüentemente, seria a forma como a botânica vem sendo ensinada: muito teórica, desestimulante, fundamentada na reprodução, repetição e fragmentação e distante da realidade dos alunos e dos problemas ambientais atuais. Percebe-se, enfim, a questão metodológica como central no processo de ensino e aprendizagem de botânica, dificultando, o entendimento e criando aversões quando não adequada. Segundo estudos recentes, é importante que os alunos tenham contato com os vegetais na natureza, aproximando-se do ambiente natural.
Abstract: Many papers hold the view that botany poses great challenge in its teaching and learning process, arising little interest and resulting in poor productivity. What factors account for this? Based on a historical and theoretical review on the development of the study of plants, it is possible to say that one of these factors is the lack of teachers with an updated Knowledge in this increasingly specific field. Another factor is the method applied in the teaching/learning process: too theoretical, unexciting, based on reproduction, repetition and fragmentation, distant from tody's reality and environmental problems. This inadequate method makes difficult for students to understand Botany, in some cases leading to aversion. Therefore, the methodological matter becomes the center of debate concerning the theaching/learning process of the study of plants. According to recent research, it is essential that students come into contact with plants within their natural environment.
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40

Bowen, Anna Kate Miller. "Characterizing the Invasion of an Understory Grass Species (Oplismenus undulatifolius (Ard.) Roem. & Schult) in the Mid-Atlantic Region of the United States." Miami University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=miami1595531995193925.

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41

Le, Roux Benjamin. "Comprendre la structure moléculaire du vivant au début du XXe siècle : Une biographie scientifique d'Henri Devaux (1862-1956)." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0068/document.

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Formé auprès de Gaston Bonnier (1853-1922) à Paris à la fin des années 1880, Henri Devaux (1862-1956) s’impose comme l’un des botanistes prometteurs de sa génération en travaillant sur les échanges gazeux chez les plantes aquatiques. De 1906 à 1932, il occupe la chaire de physiologie végétale de la Faculté des sciences de Bordeaux. Bien que ce ne soit pas son domaine de prédilection, il s’intéresse progressivement à la physico-chimie des lames (ou couches) minces et devient l’une des figures de l’école française qui émerge dans les années 1910 autour de ces questions. Tout au long du premier tiers du XXe siècle, ses travaux sur les effets de surface vont faire autorité, y compris outre-Atlantique, et lui ouvrir les portes de l’Académie des sciences. Les lames minces sont aussi un moyen pour lui de comprendre la structure et le fonctionnement des membranes cellulaires et in fine ceux du vivant à l’échelle moléculaire. En nous appuyant sur près de 10 000 pages de notes de laboratoire inédites, nous avons reconstruit l’essentiel de son cheminement intellectuel dans ce domaine.Ancré dans la foi réformée, Devaux cherche par ailleurs à montrer dans des écrits de vulgarisation que les savoirs scientifiques et la Bible concordent. Il y défend notamment une vision créationniste et fixiste du monde. Devaux lie régulièrement science et religion dans ses carnets de laboratoire et affirme même sa foi dans un article du Journal de physique
Trained by Gaston Bonnier (1853-1922) in Paris at the end of the 1880s, Henri Devaux (1862-1956) was numbered among the most promising botanists of his generation due to his work on gaseous exchanges of aquatic plants. Between 1906 and 1932, he was professor of plant physiology at the Faculty of sciences of Bordeaux. Even though it was not his primary field of study, he slowly developed an interest in the physico-chemistry of thin films (or layers) and became one of the most prominent figures of the French school that emerged on this topic in the 1910s. Throughout the first third of the 20th century, his works on surface were considered as a reference in this field, also in the United States, and opened him the doors of the Académie des sciences. Thin layers were also for him a way to understand the structure and functions of cellular membranes and, consequently, of the life on the molecular scale. Having worked on almost 10 000 pages of his unexplored laboratory notebooks, we have reconstructed the salient points of his investigative pathway in this field.Rooted in a protestant faith, Devaux also tried to show with science popularization writings that scientific knowledge and the Bible are in harmony. He defended a fixist creationist vision of the world. Devaux regularly linked science and religion in his laboratory notebooks and even claimed his faith in an article published in the Journal de physique

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Harmon, Amanda Lauren Leslie. "Herbarium Collections Management Internship." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1524744021639645.

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43

Lester, Ntsikelelo Blessings. "Preliminary investigations into the phylogenetic relationships in the genus Erica L." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/17376.

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Thesis (MSc)--University of Stellenbosch, 2006.
ENGLISH ABSTRACT: Erica is a genus of about 860 species world wide, with 700 of these found in South Africa’s southwestern and southern Cape, making it by far the most speciose genus in the Cape Floristic Region. This poses a particular challenge in the construction of a molecular phylogeny of the genus. The choice of suitably variable gene regions is a crucial decision on which the successful phylogenetic reconstruction of this important genus is critically dependent. The aim of this project was therefore to determine which DNA regions, both chloroplast and nuclear, would be sufficiently variable to give adequate informative characters that may be useful at the species level phylogenetic reconstruction. A subset of 30 species, representing the range of morphological diversity and pollinator preference within Erica, was selected for study. For each of these species the variability in eight chloroplast regions (trnL-F, matK, trnS-G, rps12- rpl20, psbAtrnH, trnC-D, rps4-trnT and trnT-L) and the nuclear ITS region was investigated. The psbA-trnH, trnC-D, rps4-trnT and trnT-L chloroplast regions were found to be problematic to amplify and to possess too few Parsimony Informative Characters to be of use in phylogenetic reconstruction. Four of the chloroplast regions, trnS-G, trnL-F, matK and rpS12-rpL20 and the nuclear ITS region could be amplified and sequenced with success. The ITS region was found to be reasonably variable, with the chloroplast genes showing less variability. The DNA extraction method employed showed itself to be of critical importance in the success of the study. Two DNA extraction protocols, both modified from the original Doyle and Doyle (1987) method, were tested. The one included double the amount of β-mercaptoethanol and Polyvinylpyrrolidone (PVP) and the other included an extended phenol: chloroform: isoamylalcohol step. These variables, together with the effectiveness of these methods on fresh vs. silica dried plant samples, were investigated to determine which of the two would yield high quantities and qualities of DNA and result in the best method for the extraction of DNA from Erica species.
AFRIKAANSE OPSOMMING: Erica is ‘n genus van omtrent 860 spesies wêreldwyd, met 700 van hierdie spesies aanwesig in die suidwes en suid Kaap van Suid Afrika, wat dit by verre die mees spesieryke genus in die Kaapse Floristiese Streek maak. Dit stel ’n besondere uitdaging in die konstruksie van ’n molekulêre filogenie van die genus. Die keuse van geskikte variërende geen-areas is ‘n belangrike besluit waarvan die suksesvolle filogenetiese rekonstruksie van hierdie belangrike genus krities afhanklik sal wees. Die doel van hierdie projek was dus om te bepaal watter DNS areas, buide chloroplas en kern, genoegsaam varieer om voldoende informatiewe kenmerke te lewer om bruikbaar te wees in ’n spesie-vlak molekulêre rekonstruksie. ’n Subgroep van 30 spesies, wat die reeks van morfologiese diversiteit en bestuiwer voorkeure in Erica verteenwoordig, is dus vir die studie geselekteer. Vir elk van hierdie spesies is die variasie in agt chloroplast areas (trnL-F, matK, trnS-G, rps12- rpl20, psbA-trnH, trnC-D, rps4-trnT en trnT-L) en die kern ITS area ondersoek. Dit was problematies om die psbA-trnH, trnC-D, rps4-trnT en trnT-L chloroplast areas te amplifiseer, en daar is gevind dat hulle te min Parsimonie Informatiewe Kenmerke besig om bruikbaar te wees in filogenetiese rekonstruksie. Vier van die chloroplas areas, trnS-G, trnL-F, matK en rpS12-rpL20 en die kern ITS kon suksesvol geamplifiseer word en die basisvolgordes kon suksesvol bepaal word. Daar is gevind dat die ITS area redelik variërend is, terwyl chloroplas areas minder variasie getoon het. Die DNS ekstraksie metode wat gebruik is het die kritiese belang van die ekstraksie metode in die sukses van die studie bewys. Twee DNS protokolle, beide gemodifiseer van die oorspronklike Doyle en Doyle (1987) metode, is getoets. Die een het dubbel die hoeveelheid β-mercaptoetanol en Polyvinylpyrrolidone (PVP) bevat, en die het ’n uitgebruide fenol: chloroform: isoamylalkohol stap ingesluit. Hierdie veranderlikes, saam met die effektiwiteit van hierdie metodes op vars teenoor silika-gedroogde plant monsters, is ondersoek om vas te stel watter een van die twee die hoogste kwaliteit en kwantiteit DNS sou lewer en dus sal lei tot die beste DNS ekstraksie metode vir Erica spesies.

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Walker, Rhonda. "Bacterial Interactions of Inoculated Price's Potato Bean (APIOS PRICEANA): A Biological Study." TopSCHOLAR®, 2011. http://digitalcommons.wku.edu/theses/1124.

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Apios priceana is a native endangered species plant found in the Southeast United States. It is characterized as a leguminous species that bears wisteria like clusters with pea like flowers, a large tuberous root and four to six inch long seed pods. It is believed the Native Americans and early European settlers relied on this species as a source of protein and utilized the seeds for cultivation of the tuberous “potato” which formed. Apios priceana contains an average of 13% fiber, 6.9% protein, 71% carbohydrate and 9 of the 11 essential amino acids needed in human diets (Walter et al.,1986). In addition, A. priceanatuberous roots contain anti-carcinogenic properties known to be used to treat prostate and breast cancer as well as lowering blood pressure and cholesterol with an added use for diabetes. If removed from the endangered species list it could prove to be a valuable agronomic crop. Its use spans human and animal consumption, bio fuel, medicinal and horticultural purposes. This research was initiated to investigate a biological symbiosis between A. priceana and known beneficial soil bacteria which may indicate growth potential of known colonies. Experimental treatments were 1) no inoculation 2) Azospirillum brasilense inoculate 3) Bradyrhizobium japonicum inoculate and 4) Rhizobium leguminosarum biovar viceae inoculate. Specimens were evaluated at 30, 60 and 90 day’s growth from emergence for taproot length, number of lateral roots and taproot girth. Due to non-germination of seeds, data presented is for treatments 2 and 3. The correlation coefficient for average taproot length, number of lateral roots developed and taproot girth per treatment was as follows: taproot length to number of lateral roots, positive correlation coefficient 0.996; taproot length to taproot girth, positive correlation coefficient 0.999; and number of lateral roots to taproot girth, positive correlation coefficient 0.991. All correlation coefficients are significant at the 0.01 level.

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Dray, Matthew William. "Effects of multiple environmental stressors on litter chemical composition and decomposition." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/68365/.

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Tree litter is a key basal resource in temperate deciduous woodlands and streams that drain them. Litter decomposition promotes carbon and nutrient cycling, fueling woodland food webs. Research to date has not thoroughly explored how ongoing environmental changes affect this process. This study used microcosm and field experiments to investigate how multiple stressors (urban pollution, elevated atmospheric CO2 and stream acidification) affected litter chemical composition, invertebrate consumption, and terrestrial and aquatic mass loss. Leaf litter chemical composition differed between ambient- and elevated-CO2 litters, and between rural and urban litters, but the direction of these responses was complex and differed between experiments. In microcosms, leaf litter consumption by terrestrial and aquatic invertebrate detritivores was species-specific. After exposure to a woodland floor or headwater streams, urban litter broke down faster than rural litter, while CO2 treatment did little to influence mass loss. The abundance, richness and diversity of terrestrial and aquatic invertebrates associated with leaf litter generally declined from 28 to 112 days in the field. Taxon richness and diversity were generally higher in elevated- than ambient-CO2 leaf litter through time, while urban leaf litter had greater diversity than rural litter after 112 days only. Abundance was greater in the circumneutral than the acid stream. Aside from leaf litter, small woody debris was also affected by CO2 treatment: elevated-CO2 twigs had a greater concentration of nitrogen and lignin, and broke down faster than ambient-CO2 twigs on a woodland floor and in headwater streams. This work highlights the complexity of invertebrate- and ecosystem-scale responses to the effects of multiple environmental stressors, with implications for nutrient cycling and food webs. Urban pollution may have a greater influence on litter chemical composition than CO2 treatment, while effects of growth condition may be more important than stream acidity in influencing decay and invertebrate communities.

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Chater, John Matthew. "THE EFFECTS OF FOLIAR NUTRIENT APPLICATIONS ON SPLIT, YIELD, AND INTERNAL FRUIT QUALITY OF 'WONDERFUL' POMEGRANATE (PUNICA GRANATUM L.)." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1510.

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Fruit split is the most important physiological disorder in pomegranate production, causing devastating crop losses worldwide. Foliar nutrient applications have been used experimentally to mitigate pomegranate fruit split but none have been conducted using the industry standard cultivar, Wonderful, and little is known about the effects of foliar nutrient applications on pomegranate. Additionally, investigations into putative health benefits of pomegranate fruit have increased interest in its production but limited evidence exists regarding effects of agricultural practices such as foliar fertilizer applications on internal fruit quality. ‘Wonderful’ pomegranate trees at 2 commercial orchards were treated with foliar applications of ZnSO4 (3000 mg∙L-1, 4000 mg∙L-1, or 5000 mg∙L-1), MgSO4 (1%, 2%, or 3%), KNO3 (1%, 2%, or 3%), or deionized (DI) water (control). Fruit were analyzed for fruit split incidence, yield, fruit number per tree, fruit diameter, fruit mass, mass of all arils in fruit, mass of 100 arils, total soluble solids (TSS), titratable acidity (TA), antioxidant activity (AA), total phenolics (TP), and mineral nutrient concentrations of leaves and fruit. Foliar applications of MgSO4 and ZnSO4 resulted in significantly lower fruit split incidence. Treatments had no significant effect on fruit number per tree, fruit diameter, and mass, mass of all arils in fruit, or mass of 100 arils. Leaf N, K, S, Mn, and Zn were significantly affected by the treatments. TSS and TA were not affected significantly by treatments. AA ranged from 77.8-84.3 percent inhibition of 2,2’-diphenyl-1-picrylhydrazyl and TP ranged from 2489-3046 mg·L-1 gallic acid equivalents, with some KNO3 treatments significantly affecting these parameters. Fruit mineral nutrient concentrations were characterized and Zn-treated trees had greater fruit Zn concentrations. The results suggest that foliar ZnSO4 or MgSO4 could be used to decrease fruit split incidence and increase nutritional content of ‘Wonderful’ pomegranate and any of the three tested foliar nutrients could be applied as a foliar fertilizer without negatively impacting fruit yield, size, internal quality, bioactivity, or mineral nutrient concentration.

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Mwitwa, Jacob Pacific. "Growth and physiological parameters related to shoot dieback in Pterocarpus angolensis DC seedlings." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/20431.

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Thesis (PhD)--Stellenbosch University, 2004.
ENGLISH ABSTRACT:Six experiments, five in the glasshouse and one in the field near Nelspruit, were carried out to ascertain the effect of factors related to shoot die-back, and of water treatments on the growth and physiological responses of Pterocarpus angolensis seedlings. The study was undertaken to broaden the knowledge and understanding of the phenomenon of shoot die-back in order to enhance our ability to regenerate the species. The following experiments were carried out (a) Assessment of biomass accumulation; anatomical characteristics of the shoot apical meristem; foliar, stem and root concentration of micro- and macronutrients associated with each phenophase, (b) Effect of seedling age and seed source on the occurrence of shoot die-back under field conditions; (c) Water treatment effects on ChI. afluorescence traits of£'. angolensis seedlings obtained by assessing the fluorescence yield of photosynthetic samples subjected to dark- and light-adaptation; (d) Genetic variation in shoot die-back and other traits of sixteen halfsib families of £.. angolensis from Malawi, Namibia and Zambia grown over two die-back seasons. Experiments conducted revealed the following 1. Patterns of growth observed in phenophases are indicators of seasonal changes in annual biomass allocation to the shoot and root. Phenophases such as leaf loss and stem senescence, whether shoot die-back occurs completely or not, are directly related to the decline in above-ground biomass and declined rate of increase in root biomass respectively. Leaf flush, expansion and maturation result in increased biomass accumulation whilst shoot die-back has a minimal downregulatory effect on root biomass accumulation compared to the shoot. Shoot dieback is not sudden, therefore from the first day of germination, seedlings synchronise growth and development with the occurrence of shoot die-back. 2. Phenophasic concentration of foliar N, Ca and Mg, stem Fe and Cu and root concentrations of P, K, Mg, Fe and B are associated with shoot die-back. Patterns of mineral nutrient concentration obtained in foliage and roots but to a lesser extent in the stem, may be related to nutrient remobilisation during shoot dieback. Higher relative mineral nutrient changes during leaf yellowing and shoot die-back may be an indication of the removal of significant volumes of mobile nutrients from senescing tissues. 3. The volume of the shoot apex of E. angolensis remains constant during different phenophases which points to seasonal uniformity in the size of the apical dome. Changes in phenology associated with declined growth, or shoot die-back, is revealed through declined cell number in the tunica which is a reflection of declined mitotic activity. 4. Shoot die-back occurs in all seedlings from nursery stock planted under field conditions and all seedlings of up to two years experience complete shoot dieback. Shoot die-back takes place irrespective of seed source or the age of nursery stock that is planted. Survival after the first shoot die-back is normally low. Water treatments had no significant effect on the function of PSIJ reaction centres of P. angolensis nursery seedlings. In the case of both dark- and light-adapted leaves, water treatment had no significant effect on the measured Chi. a fluorescence parameters or the calculated parameters (specific activities, phenomenological fluxes, structure-function and performance indexes and drivingforces). 5. Water treatments affect the shape of ChI. a fluorescence transients of lightadapted compared to that of dark-adapted photosynthetic samples of E. angolensis. No significant water treatment effect was obtained for extracted and technical Chi. afluorescence parameters, specific fluxes, quantum efficiencies and phenomenological fluxes. Quantum yield, relative electron transport and quantum yield limitation, de-excitation rate constants, structure-function, performance indexes and driving forces were also not significantly different across water treatments.6. Genetic variation was observed to exist among 16 halfsib families from Malawi, Namibia and Zambia. High heritabilities were obtained for shoot die-back and other traits, indicating that shoot die-back is genetically controlled. The trait is passed from parents to offspring and it is highly probable that it occurs, throughout its natural range, in all seedlings. Since shoot die-back is genetically programmed, it remains crucial to the ability of a seedling to regenerate in the following rainy season
AFRIKAANSE OPSOMMING:Ses eksperimente, vyf in die glashuis en een in die veld naby Nelspruit, is uitgevoer om die effek van faktore wat verwant is aan die terugsterwing van lote op saailinge, sowel as om die effek van waterstres op die groei en fisiologiese responsies van Pterocarpus angolensis saailinge, te ondersoek. Die studie is ondemeem om die kennis en begrip aangaande die regenerasie-dinamika van die spesies te verbeter. Die volgende eksperimente is uitgevoer: (a) Evaluering van die effek van jisiologiese veranderings op biomassa; blaar-, stam- en wortelkonsentrasies van spoor- en makro-voedingselemente, en anatomiese eienskappe van die apikale meristeem van die lote. (b) Effek van saailingouderdom en saadbron op die voorkoms van lootterugsterwing onder veldtoestande. (c) Waterbehandelingseffekte op Chi. ajluorisensie eienskappe van ,e. angolensis saailinge wat verkry is deur die jluorisensie te evalueer van fotosintesemonsters wat aan donker- en lig-adaptasies onderwerp is. (d) Genetiese variasie in loot-terugsterwing en ander groei-eienskappe van 16 halfsib families van ,e. angolensis vanaf Malawi, Namibia en Zambia wat gekweek is oor twee terugsterj-seisoene. Die eksperimente het die volgende aan die lig gebring: 1. Groeipatrone waargeneem gedurende die fenofases is indikatore van seisoenale veranderings in jaarlikse biomassa allokasies aan die loot en die wortels. Fenofases soos blaarverlies en lootafsterwing, ongeag of loot-terugsterwing volledig is of nie, is direk verwant aan die afname in bogrondse biomassa en afnemende tempo van toename in wortelbiomassa respektiewelik. Bottende blare, vergroting en rypwording van blare lei tot toenemende biomassa akkumulasie terwyl loot-terugsterwing 'n minimale afskalende effek op akkumulasie van wortelbiomassa het in vergelyking met die van die loot. Loot-terugsterwing is nie skielik, met ander woorde vanaf die eerste dag van ontkieming sinchroniseer saailinge groei en ontwikkeling met die voorkoms van loot-terugsterwing. 2. Fenofase konsentrasies van en veranderings in blaar N en Ca en loot Fe, asook veranderings in waargenome wortel N, K, Ca, Mn, Cu, Zn en B is sterk geassosieer met loot-terugsterwing. Patrone van minerale voedingselementkonsentrasies wat in blare en wortels, en in minder mate in die loot, verkry is, mag direk verwant wees aan hermobilisering van voedingselemente gedurende loot-terugsterwing. Hoe relatiewe minerale voedingselementveranderings gedurende die vergeling van blare en lootterugsterwing mag 'n indikasie wees van die verwydering van betekenisvoUe hoeveelhede mobiele nutriente vanaf sterwende weefsel. 3. Die volume van die groeipunt van r. angolensis bly konstant gedurende verskillende fenofases wat dui op seisoenale uniformiteit in die grootte van die apikale koepel. Veranderings in fenologie ge-assosieer met afnemende groei, of loot-terugsterwing, word gerejlekteer deur afnemende selgetaUe in die tunika wat dui op afnemende mitotiese aktiwiteit. 4. VoUedige loot-terugsterwing kom voor in aUe saailinge vanaf die kwekery wat in die veld geplant word tot op die ouderdom van twee iaar. Dit kom voor angeag van saadbron of ouderdom van saailinge ten tye van planting. Oorlewing na aanvanklike loot-terugsterwing is normaalweg laag. 5. Water behandelings het geen beduidende effek op die funksie van PSII reaksiesentra van r. angolensis kewekery-saailinge gehad. Vir beide donker- en lig-aangepaste blare is geen beduidende waterbehandelingseffek verkry vir waargenome ChI. a jluoresensie parameters of die berekende parameters (spes ifieke aktiwiteite, jenomenologiese jlukse, struktuur-funksie-indekse, "perjormance-indekse oj" driving forces" ). 6. Genetiese variasie tussen 16 halfsibfamilies vanaf Malawi, Namibie en Zambie is verkry vir loot-terugsterwing en ander groei-eienskappe. Dit dui op genetiese beheer van terugsterwing en dat die eienskap oorerjbaar is, en waarskynlik in die hele natuurlike verspreidingsgebied van die spesies in aUe saailinge voorkom. Aangesien loot-terugsterwing gene ties geprogrammeer is, is dit noodsaaklik vir die vermoe van die plant om in die volgende reenseisoen te regenereer.

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Gregory, Samuel James. "Investigation into the relationship between aluminium treatment and the superoxide dismutase (SOD) enzyme system in Lolium perenne (L. perenne cv. Nui) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science (with Honours) in Plant Biology at Massey University." Massey University, 2009. http://hdl.handle.net/10179/1216.

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Lolium perenne cv. Nui is a cultivar of ryegrass grown throughout New Zealand in pastures due to favourable traits such as high palatability for livestock and its ability to withstand intensive grazing. However, the productivity of pastures is reduced when levels of aluminium and other metals accumulate in soils to toxic levels, a phenomenon referred to as the ‘acid soil syndrome’. In response to this toxicity, plants activate a series of antioxidant reactions, with one catalysed by the superoxide dismutase (SOD) enzymatic system. The enzyme system comprises three isoenzymes, a Cu/ZnSOD, FeSOD and a MnSOD which catalyse the same reaction but differ in amino acid sequence, molecular mass and the metal ion co-factor (hence Cu/ZnSOD, FeSOD and MnSOD). Together these isoenzymes combat the damaging effect of superoxide radicals which accumulate due to metal toxicity. In this thesis, the isolation of genes encoding isoenzymes of the SOD enzyme from L. perenne cv. Nui is described. As well, the growth of L. perenne cv. Nui and changes in expression of the SOD genes encoding each isoenzyme in response to aluminium treatment (0.2mM AlCl3) is investigated. A 1072 bp FeSOD gene sequence and a 705 bp MnSOD gene sequence were isolated from shoot tissue of L. perenne cv. Nui using a combination of RT-PCR with degenerate primers and 3'-RACE. The FeSOD gene comprised 572 bp of the coding sequence and 500 bp of 3'-UTR while the MnSOD gene comprised 508 bp of coding sequence and a 197 bp 3'-UTR. By alignment of each sequence with the gene from the database with highest identity it was predicted that the translation start codon (ATG) is located a further 196 bp upstream for the FeSOD gene (aligned with an Oryza sativa FeSOD sequence as a reference) and a further 152 bp upstream for the MnSOD sequence (aligned with a Triticum aestivum MnSOD sequence as a reference). Using RT-PCR with degenerate primers, a 313 bp CuSOD sequence was predominantly cloned from shoot tissue of L. perenne cv. Nui, but it was not possible to generate the 3'-UTR using 3'-RACE. For growth analysis, seedlings of L. perenne cv. Nui were germinated and acclimatised in Hoagland’s solution, and then subjected to either aluminium treatment (0.2mM AlCl3) or no treatment to act as a control over a designated time course of 0, 4, 8, or 24 hours. Two growth trials were conducted that differed in the age of seedlings used and plant tissues were separated into root and shoot tissues. Similar growth trends were observed in both trials, but the sampling regime in the second growth trial meant that statistical analysis could be carried out. In this trial, analysis revealed that over a time course of 24 hours exposure to 0.2mM aluminium, both root and shoot tissue fresh weight did not significantly differ when compared to the control (no aluminium). A general trend of an increase in root and shoot fresh weight was observed in plants treated with aluminium, but this trend was not significant at P=0.05. No significant change in fresh weight partitioning from shoot to root, or root to shoot in response to aluminium was also observed. Using semi-quantitative Reverse Transcriptase-Polymerase Chain Reaction (sqRTPCR) and primers based around the 3'-UTR with RNA isolated from plants grown in the second hydroponic trial, it was determined that under the conditions used, expression of the FeSOD and MnSOD genes isolated in this study were neither up-regulated or downregulated in response to aluminium treatment in both shoot and root tissue. Further, using degenerate primers to detect expression of one or more genes encoding the Cu/ZnSOD isoenzyme, total expression of the Cu/ZnSOD isoenzyme was also unresponsive to aluminium treatment.

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Dritsas, Lawrence. "The Zambesi Expedition : African nature in the British scientific metropolis." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/2161.

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This thesis investigates the geography in and of Victorian scientific practice by examining the Zambesi Expedition (1858-1864), which was led by the Scottish explorer David Livingstone. A team of assistants accompanied Livingstone: Dr. John Kirk, Dr. Charles Meller, Thomas Baines, Richard Thornton and Charles Livingstone. The official purposes of this expedition, funded by the British Foreign Office, were to catalogue the natural resources of the regions adjacent to the Zambezi River in order to identify new sources of raw materials for British industry and to introduce commercial markets to supplant the slave trade. The scientific results of the Zambesi Expedition have never been catalogued. Only limited attention has been paid to the ways in which science was made in the field and how it returned to Britain In order to address these issues, a survey was made of relevant scientific literature to identify published analyses of the data and specimen collections produced by the Expedition’s staff. Extant specimen collections were located and examined along with archival records and correspondence. The combined manuscript and material evidence reveals that scientific concerns were an important justification for the Expedition. Fieldwork practices are examined in depth and an ideology of technology, expressed in different ways, is shown to have structured the encounters between the British and the locals. The Expedition’s members based their assumed superiority upon technological skill, especially their abilities to understand the environment and to command power—in terms of steam navigation, instrumental authority and the naming of natural productions. Power differentials were apparent in the field when the information possessed by local informants was required for the success of the scientific goals of the expedition. Credibility in the field became a tenuous quality negotiated between local informants, explorers and the metropolitan scientific community. The expedition’s members, as interpreters, were required to navigate the social and physical spaces of the field and the metropolis in order to produce and present credible knowledge. The thesis examines for the first time elements of the reception of the expedition by considering the publication of its scientific results. Critics’ voices are used to uncover those attitudes of the time that judged explorers—and this expedition—according to their prior experiences, social connections and field skills. The work of the Expedition, then, was performed in different spaces and at different scales; operating within and between the field and metropolis and actively linking local practices to global networks. These multivalent practices enabled and circumscribed a British construction of African nature.

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Wunderly, Martin A. "Defining Zostera marina (Eelgrass) Restoration Sites in Virginia's Coastal Bays with Aerial Images and Bathymetric Mapping." Miami University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=miami1261160088.

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Dissertations / Theses on the topic 'Science / Botany'

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