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A study of the primary vascular system and evolution in the familyCupressaceae.Pillman, Anne. January 1978 (has links) (PDF)
Thesis (M.Sc.) -- University of Adelaide, Dept. of Botany, 1979.
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Ultrastructural studies on sieve element plastids and P-proteins in the primary phloem of legumesPalevitz, Barry Allan, January 1971 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.
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Genetic analysis of leaf vascular patterning in Arabidopsis thalianaSteynen, Quintin John, University of Lethbridge. Faculty of Arts and Science January 2001 (has links)
I have isolated and characterized a recessive mutation in the Forked (FKD) gene that results in the abnormal initiation of vascular bundles in the foliar organs, such that the apices of the vascular bundles initiate freely. Once initiated, the development of Fkd vascular bundles is like wild type, generating an open vascular pattern of similar complexity to the closed venation pattern of wild type. Despite the significant alteration in the vascular pattern, Fkd plants are morphologically indistinct from wild type. fkd mutants do not show altered sensitivity to the effects of auxin and show additive phenotypes with auxin response mutants, suggesting the FKD is part of a pathway acting independently of auxin. The similarity of the open vascular pattern of Fkd plants to that of ancestral vascular plants suggests that acquisition of this pathway may have been critical in the evolution of the closed vascular pattern. / x, 55 leaves : ill. ; 28 cm.
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Autobahn : a gene that has a role in auxin influx in Arabidopsis leavesGarrett, Jasmine Jay Tamara, University of Lethbridge. Faculty of Arts and Science January 2005 (has links)
The development of leaf vascular patterns is a highly regulated process. The plant hormone
auxin is critical for vascular patterning: auxin canalization is proposed to cause files of cells to accumulate higher auxin levels and develop into veins. Thus, the response of cells to auxin and transport of auxin are critical to establish proper cell fate. We have characterized a mutation in the Arabidopsis thaliana gene name AUTOBAHN (ABN). abn leaves produce leaves that proliferate disorganized, overlapping veins parallel to the midvein with no differentiation of higher order veins. abn leaves show no normal aspects of the secondary auxin response though double mutant analysis suggest that ABN functions independently of previously characterized auxin response pathways. Wild type plants grown on an influx inhibitor phenocopy abn suggesting that abn is defective in carrier-mediated auxin influx. / x, 69 leaves : ill. ; 28 cm.
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The unhinged gene is essential for vascular complexity in the leaves of ArabidopsisCormack, Ryan David, University of Lethbridge. Faculty of Arts and Science January 2006 (has links)
The complex vasculature seen in the vascular plants provides a scaffolding of
structural support and is responsible for the movement of water, minerals, photosynthate
and some hormones. The auxin canalization model proposes that a positive feedback
mechanism causes auxin-transporting cells to become vascular cells. We have isolated a
leaf-patterning mutant, unhinged (unh), which shows a simplified leaf vascular pattern
with more freely ending veins and fewer secondary veins. Expression of the
ATHB8::GUS reporter construct indicates that the UNH gene acts prior to procambial
patterning of the first presumptive secondary veins. Expression of the auxin responsive
reporter gene DR5::GUS is reduced in unh leaves and roots, indicating that UNH may be
involved in auxin signaling. Increasing the level of auxin in unh leaves through the
addition of auxin transport inhibitors, low concentrations of 2,4-dichlorophenoxyacetic
acid, and through introducing unh into mutants in which auxin transport is defective
partially rescues the unh phenotype, supporting this hypothesis. The unh mutation maps
to a 60kb region near the top of chromosome IV. No other leaf vascular mutant or auxinassociated
mutant have been reported in this area, thus UNH represents a novel
component of leaf vascularization and auxin signaling. / xi, 65 leaves : ill. (some col.) ; 29 cm.
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Investigating the role of pyrophosphate fructose 6-phosphate 1-phosphotransferase in phloem loading /Smith, Marthinus Luther. January 2008 (has links)
Thesis (MSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.
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Chemical hydrology of vascular plant growth : role of root-fungus associationsBalogh, Zsuzsanna, January 2006 (has links) (PDF)
Thesis (Ph. D.)--Washington State University, August 2006. / Includes bibliographical references (p. 82-98).
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Coupling kinetic models and advection-diffusion equations to model vascular transport in plants, applied to sucrose accumulation in sugarcaneUys, Lafras 12 1900 (has links)
Thesis (PhD (Biochemistry))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: The sugarcane stalk, besides being the main structural component of the plant, is also the major
storage organ for carbohydrates. Sucrose forms the bulk of stored carbohydrates. Previous
studies have modelled the sucrose accumulation pathway in the internodal storage parenchyma
of sugarcane using kinetic models cast as systems of ordinary differential equations. Typically,
results were analysed with methods such as metabolic control analysis. The present study extends
those original models within an advection-diffusion-reaction framework, requiring the use
of partial differential equations to model sucrose metabolism coupled to phloem translocation.
Let N be a stoichiometric matrix, v a vector of reaction rates, s a vector of species concentrations
and r the gradient operator. Consider a coupled network of chemical reactions where
the species may be advected with velocities, U, or diffuse with coefficients, D, or both. We
propose the use of the dynamic system, s + r (Us) + r (Drs) = Nv;
for a kinetic model where species can exist in different compartments and can be transported
over long distances in a fluid medium, or involved in chemical reactions, or both. Darcy’s
law is used to model fluid flow and allows a simplified, phenomenological approach to be
applied to translocation in the phloem. Similarly, generic reversible Hill equations are used to
model biochemical reaction rates. These are also phenomenological equations, where all the
parameters have operationally defined interpretations.
Numerical solutions to this formulation are demonstrated with time-courses of two toy
models. The first model uses a simple “linear” pathway definition to study the impact of
the system geometry on the solutions. Although this is an elementary model, it is able to
demonstrate the up-regulation of photosynthesis in response to a change in sink demand. The
second model elaborates on the reaction pathway while keeping the same geometry definition as
the first. This pathway is designed to be an abstracted model of sucrose metabolism. Finally,
a realistic model of sucrose translocation, metabolism and accumulation is presented, spanning
eight internodes and four compartments. Most of the parameters and species concentrations
used as initial values were obtained from experimental measurements.
To analyse the models, a method of sensitivity analysis called the Fourier Amplitude Sensitivity
Test (FAST) is employed. FAST calculates the contribution of the possible variation in
a parameter to the total variation in the output from the model, i.e. the species concentrations
and reaction rates.
The model predicted that the most important factors affecting sucrose accumulation are the
synthesis and breakdown of sucrose in futile cycles and the rate of cross-membrane transport
of sucrose. The models also showed that sucrose moves down a concentration gradient from
the leaves to the symplast, where it is transported against a concentration gradient into the
vacuole. There was a net gain in carbohydrate accumulation in the realistic model, despite an
increase in futile cycling with internode maturity.
The model presented provides a very comprehensive description of sucrose accumulation
and is a rigorous, quantitative framework for future modelling and experimental design. / AFRIKAANSE OPSOMMING: Benewens sy strukturele belang, is die suikerrietstingel ook die primêre bergingsorgaan vir koolhidrate.
Die oorgrote meerderheid van hierdie koolhidrate word as sukrose opgeberg. Studies
tot dusver het die metabolisme rondom sukroseberging in die parenchiem van die onderskeie
stingellitte as stelsels gewone differensiaalvergelykings gemodelleer. Die resultate is ondermeer
met metaboliese kontrole-analise geanaliseer. Hierdie studie brei uit op die oorspronklike
modelle, deur gebruik te maak van ’n stromings-diffusie-reaksie-raamwerk. Parsiële differensiaalvergelykings
is geformuleer om die metabolisme van sukrose te koppel aan die vloei in die
floëem.
Gestel N is ’n stoichiometriese matriks, v ’n vektor van reaksiesnelhede, s ’n vektor van
spesie-konsentrasies en r die differensiaalvektoroperator. Beskou ’n netwerk van gekoppelde
reaksies waar die onderskeie spesies stroom met snelhede U, of diffundeer met koëffisiënte D,
of onderhewig is aan beide prosesse. Dit word voorgestel dat die dinamiese stelsel,
_s + r (Us) + r (Drs) = Nv;
gebruik kan word vir ’n kinetiese model waar spesies in verskeie kompartemente kan voorkom
en vervoer kan word oor lang afstande saam met ’n vloeier, of kan deelneem aan chemiese
reaksies, of albei. Darcy se wet word gebruik om die vloeier te modeller en maak dit moontlik
om ’n eenvoudige, fenomenologiese benadering toe te pas op floëem-vervoer. Eweneens word
generiese, omkeerbare Hill-vergelykings gebruik om biochemiese reaksiesnelhede te modelleer.
Hierdie vergelykings is ook fenomenologies van aard en beskik oor parameters met ’n duidelike
fisiese betekenis.
Hierdie omvattende raamwerk is ondermeer gedemonstreer met behulp van numeriese oplossings
van twee vereenvoudigde modelle as voorbeelde. Die eerste model het bestaan uit ’n
lineêre reaksienetwerk en is gebruik om die geometrie van die stelsel te bestudeer. Alhoewel
hierdie ’n eenvoudige model is, kon dit die toename in fotosintese as gevolg van ’n verandering
in metaboliese aanvraag verklaar. Die tweede model het uitgebrei op die reaksieskema
van die eerste, terwyl dieselfde stelselgeometrie behou is. Hierdie skema is ontwerp as ’n abstrakte
weergawe van sukrosemetabolisme. Ten slotte is ’n realistiese model van sukrosevervoer, metabolisme en berging ontwikkel wat agt stingellitte en vier kompartemente omvat. Die meeste
parameters en konsentrasies van biochemiese spesies wat as aanvanklike waardes in die model
gebruik is, is direk vanaf eksperimentele metings verkry.
Die Fourier Amplitude Sensitiwiteits-Toets (FAST) is gebruik om die modelle te analiseer.
FAST maak dit moontlik om die bydrae van parameters tot variasie in modeluitsette soos
reaksiesnelhede en die konsentrasies van chemiese spesies te bepaal.
Die model het voorspel dat sintese en afbraak van sukrose in ’n futiele siklus, asook transmembraan
sukrosevervoer, die belangrikste faktore is wat sukrose-berging beïnvloed. Die model
het ook getoon dat sukrose saam met ’n konsentrasiegradiënt beweeg vanaf die blare tot by
die stingelparenchiem-sitoplasma, van waar dit teen ’n konsentrasiegradiënt na die vogselholte
(vakuool) vervoer word. Volgens die realistiese model was daar ’n netto toename in die totale
hoeveelheid koolhidrate, ten spyte van ’n toename in die futile siklus van sukrose in die ouer
stingellitte.
Die model wat in hierdie proefskrif voorgestel word verskaf ’n uitgebreide, omvattende
beskrywing van sukroseberging. Voorts stel dit ’n rigiede kwantitatiewe raamwerk daar vir
toekomstige modellering en eksperimentele ontwerp.
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Modelling the auxin-mediated vein formation system in plant leavesSlingerland, Martin Jacob (Marc), University of Lethbridge. Faculty of Arts and Science January 2007 (has links)
The plant hormone auxin is involved in a wide range of developmental phenomena in
plants. It carries out many of its effects through a signalling network involving the regulation
of specific genes, including those involved in its own polar transport between cells.
These transporters are able to be redistributed between cell faces, causing the asymmetric
auxin transport that is a key requirement for the formation of vein patterns in leaves.
In this thesis I describe the development of a biochemical kinetics-based model of auxin
signalling and transport in a single cell, which displays biologically plausible responses
to auxin application. The single-cell model then serves as the basis for a multicell model
of auxin-mediated vein formation at a very early stage of leaf formation in Arabidopsis
thaliana. / ix, 73 leaves : ill. ; 29 cm.
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Abundance patterns for vascular epiphytes in a tropical secondary forest, Costa RicaKull, Matthew Austin. January 2007 (has links)
Thesis (M.S.)--State University of New York at Binghamton, Department of Biological Sciences, 2007. / Includes bibliographical references.
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