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Tengelin, Fredrik, Kristian Roos, and Johan Axelsson. "En jämförelse av stomval till skolan i Hagfors." Thesis, Karlstad University, Faculty of Technology and Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-1820.
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<p>Sammanfattning</p><p>Detta arbete baseras på nybyggnationen och ombyggnationen av skolan i Hagfors som NCC gör för Hagfors kommun. Uppgiften är att göra en jämförelse av olika stomalternativ; platsgjuten betong, prefabricerad betong och stålstomme på nybyggnationen med hänsyn till tid, ekonomi och miljöpåverkan. Den nybyggda delen kommer att bli ca 7000 m2 fördelat på tre plan och stommen utgörs i dagsläget till största del av prefabricerad betong.</p><p>De frågeställningarna som behandlas i arbetet är</p><p>• Vilket material är mest fördelaktigt utifrån ett tidsperspektiv?</p><p>• Vilket material/stomlösning är ur ett ekonomiskt perspektiv att föredra?</p><p>• Hur påverkas miljön av de olika stomsystemen?</p><p>Målet med examensarbetet är att välja den mest lämpliga stomlösningen för nybyggnationen av Visa Bildningscentrum i Hagfors på uppdrag av NCC, ur ett ekonomiskt och tidsmässigt perspektiv. De alternativ som ska undersökas och jämföras är stålstomme, prefabricerad betongstomme och platsgjuten stomme.</p><p>Syftet med arbetet är att kunna få en inblick i hur olika stomsystem utformas, vilka byggmetoder som används, samt göra en jämförelse av stomsystemen som kan generera en relevant slutsats. Vi ska studera ett objekt där stommen redan är vald för att på så sätt få en mer verklighetsanknuten förståelse för problematiken vid val av stomme.</p><p>Problemlösningen baseras på laster, pelardimensioner, balkdimensioner, antal pelare och balkar. Dessa har tillhandahållits av NCC. Beräkningar genomfördes för att specificera armeringsmängd i betongstommarna och för att dimensionera stålstommen. För att se vad de olika stomalternativen kostade användes BidCon för att få fram en kalkyl på stommen, inklusive material och arbetskostnader. Resultatet av detta blev att den platsgjutna betongstommen kostar 4 104 000 kr, stålstommen kostar 5 835 000 kr och den prefabricerade betongstommen kostar 4 558 000 kr.</p><p>Om man ska se till tiden är det den prefabricerade betongstommen som tar kortast tid vid förutsättningen att leveranser och samordning sker planenligt. Den platsgjutna stommen är den mest tidskrävande bland annat beroende på långa uttorkningstider och faktumet att platsgjuten betong är mycket väderberoende.</p><p>Sett utifrån ett miljöperspektiv föll valet på att använda betong på grund av lägre energiförbrukning och utsläpp vid tillverkning, jämfört med stål, samt att en byggnad i betong har en stor värmetröghet vilket skapar förutsättningar för ett lägre och jämnare energibehov i den färdiga byggnaden. Transporter till byggplatsen har även betydelse på grund av att de prefabricerade betongelementen i detta fall tillverkas i och levereras från Tyskland.</p><p>Vid tillverkning av prefabricerade element minimeras de flesta problem som väder orsakar vid användning av platsgjuten betong. All produktion sker inomhus i fabriker och förutom att problem på grund av väderförhållanden försvinner så minskas även olycksrisken. Prefabricerat byggande har dock nackdelen att det är mycket störningskänsligt på grund av att det förlitar sig helt på att logistiken fungerar utan några förseningar. Problem med arbetsmiljö, exempelvis belastningsskador och olycksrisker, kan man flytta från byggarbetsplatsen till en fabrik där arbetsmiljön kan kontrolleras på ett bättre sätt genom att välja en prefabricerad stomme, även om man inte helt kan undvika dem.</p><p>I rapporten finns exempel på hur beräkningar genomförts, kalkyler på stålstommen och den platsgjutna betongstommen och ritningar på nybyggnationen.</p><p>Arbetet utförs på uppdrag av NCC med Bo Rom och Thomas Boman som externa handledare. Handledare på universitetet är Carina Rehnström.</p>
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Enokson, Oskar, and Emil Holm. "Kommersiellt byggande i trä : En undersökning av trä som stomval i kontorsbyggnader." Thesis, Uppsala universitet, Byggteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-360509.
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The objective of this report is to evaluate why wooden frameworkis not used more frequently in larger buildings when both contractors and clients profile themselves as environmental friendly, with future goals of becoming neutral to the environment. The biggest incentive to build more with a wooden framework is how the choice of material impacts the climate and work environment at the construction site. It is hard to put a financial value on the benefits for the climate and work environment that a wooden framework provides. This is one of the reasons why the wooden frame is being neglected in the bidding process because it is often more expensive at that point in the construction process. Construction industries around the world has a large negative impact on the climate and greenhouse effect and contributes to 40 % of the global carbon emissions. Statistics show that the manufacturing of concrete and steel products used in constructionemits more than twice as much carbon dioxide as wood-based materials. Wood-based materials binds carbon dioxide during its life span and releases it when the product is obsolete. Many consider the healthier work environment as a very significant benefit of building with a wooden framework, especially theconstruction workers themselves. A healthy work environment forthe construction workers increase well-being and efficiency at the construction site. Project management is easier when the work situation for the construction workers is prosperous. The wooden framework contributes to a healthier workplace and reduces dust, vibrations from machines and noise considerably, the air is also cleaner and it has a better smell to it. Buildings with wooden framework is often being built under a tentof some sort to prevent moisture and rain to penetrate the building causing damage. The tent itself is very expensive tobuild under, and it’s a major reason why framework made of wood is more expensive in the bidding process. Contractors supplying framework-systems made of wood are constructing the building in the same way a steel and concrete frame would be constructed, without materials sensitive to moisture. The wooden frame dries out faster than a frame made of steel and concrete. If the two prefabricated systems are assembled in a similar way the wooden framework can better compete on equal terms with other framework systems in the bidding process. The crucial part for an increased usage of wooden frameworks in commercial office buildings is that the contractors and clientsreach a turning point. A turning point in which they accept that the wooden framework appears more expensive in the bidding process but yet they choose it because of the benefits it provides. Only then can the right circumstances be achieved, which leads to an increased use of wooden frameworks in the market.<br>Målet med den här studien är att göra en utvärdering på varför det inte byggs fler större projekt med en trästomme när både entreprenörer och beställare har högt uppsatta framtida miljömål och vill profilera sig som miljömedvetna. De starkaste incitamenten för att bygga mer i trä är hur materialvalet påverkar klimatet och arbetsmiljön på arbetsplatsen. Det är svårt att sätta ett värde i pengar på miljö och arbetsmiljö, vilket är en av anledningarna till att ett stomsystem i trä ofta väljs bort i anbudsskedet då kalkylen för en trästomme ofta påvisar att trästommen är dyrare i den delen av byggprocessen. Världens byggindustrier har en stor negativ klimatpåverkan på växthuseffekten och står idag för 40 % av de globala koldioxidutsläppen. Statistik visar att framställningen av betongprodukter och stålarmering står för mer än dubbelt så stora utsläpp koldioxidutsläpp som träbaserade material. Träbaserade material binder koldioxid under sin livstid och avger det när produkten är förbrukad. Ett träbaserat material avger aldrig mer koldioxid än den binder under sin livscykel och har därmed en neutral påverkan på klimatet. Många upplever arbetsmiljön som en stor fördel med arbetet i en trästomme, framförallt yrkesarbetarna. En sund arbetsmiljö för yrkesarbetare ökar trivsel och effektivitet i projekt. Projektstyrningen underlättas när yrkesarbetarnas välmående och arbetssituation är så bra som möjligt. Att bygga hus med trästomme medför färre arbetsmoment och är förebyggande mot vibrationsskador orsakade av förborrning och användande av hårt vibrerande maskiner som slagborrar och bilmaskiner. En trästomme minskar damm och buller avsevärt, samt att luften är renare och det luktar fräscht. Trähus byggs ofta under väderskydd eller tält för att förebygga mot regn och byggfukt som kan medföra fuktskador. Det är dyrt att resa stomme under tält med traverskranar och det är en stor anledning till att trästommar är dyrare vid stomresning. De träentreprenörer som levererar och monterar trästommar har börjat resa trästommen till byggnader utan fuktkänsliga trämaterial till att huset är tätt. När huset är tätt torkar byggnaden ut fortare än ett hus av betong och invändiga arbeten med fuktkänsliga material kan påbörjas. När en trästomme monteras på samma sätt utan tält som en stålstomme med betongbjälklag blir den mer konkurrenskraftig i anbudsskedet. Det som är avgörande för utökat användande av trästomme i kommersiella kontorsbyggnader är att entreprenörer och beställare kommer till en brytpunkt. En brytpunkt där de accepterar att trästommen ser dyrare ut i anbudsskedet men ändå väljer den på grund av de positiva effekterna på arbetsmiljö, brukarupplevelse och långsiktig hållbarhet. Först då kan rätt förutsättningar skapas för att trästommen ska bli mer konkurrenskraftig mot övriga marknaden.
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Rönnberg, Andreas, and Daniel Lindblom. "Bollhall i Säffle : En jämförelse mellan stål- och trästomme." Thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-73065.
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SÄBO AB will construct a sports Centre in Säffle municipality, the sports Centre will be used for football practice and the outer dimension of the sports Centre was determined to be 40x70 m. The purpose was to demonstrate price and carbon dioxide emissions for the production of glulam and steel frames, the cross-laminated timber, CLT, and Paroc curtain wall. This was done by dimensioning the frames according to the Eurocodes and generate producing prices for the materials, also a calculation was made for carbon dioxide emissions for the alternatives in terms of transport and production. To calculate a key figure for earned carbon dioxide per invested capital, the differences could be more clearly demonstrated. Another aim was to produce a design proposal. The glulam frame consists of glulam columns with three-joint truss in glulam, drawstick and windstrut in round steel. The roof trusses have a span of 40 m and the ceiling height indoors is 7.5 m. This frame became the most expensive but more beneficial in terms of carbon dioxide emissions for production. The steel frame consists of HEA columns and saddle framework as roof, the roof trusses have a span of 40 m and the ceiling height indoors is 7.5 m. This frame was the cheapest but has the largest emissions of carbon dioxide from the production. The curtain wall of CLT released the least carbon dioxide but became the most expensive alternative, the curtain wall of Paroc became the cheapest option but released most carbon dioxide from these two alternatives.<br>SÄBO AB skall uppföra en hallbyggnad i Säffle kommun, hallbyggnaden ska användas till fotbollsutövning och storleken på fotbollsplanen kommer vara en 7-mannaplan. Yttermåttet på bollhallen bestämdes till 70 x 40 meter. Målet var att påvisa pris och koldioxidutsläpp för framställning av limträ- och stålstomme, och utfackningsvägg av KL-trä samt av Paroc. Detta gjordes genom dimensionering av stommarna enligt eurokoderna och genom att priser togs fram för materialen, även en beräkning gjordes för koldioxidutsläpp för alternativen vad gäller transport och framställning. Genom att ett nyckeltal för tjänad koldioxid per investerat kapital togs fram kunde skillnaderna påvisas på ett tydligare sätt. Ett ytterligare mål var att ta fram ett gestaltningsförslag. Limträstommen består av limträpelare med treledstaktolar i limträ, dragband och vindstag i rundstål. Takstolarna har en spännvidd på 40 m och den fria takhöjden inomhus är 7,5 m. Denna stomme blev dyrast men mer fördelaktig vad gäller koldioxidutsläpp för framställning. Stålstommen består av HEA-pelare och sadelfackverkstakstolar, takstolarna har spännvidden 40 m och den fria takhöjden inomhus är 7,5 m. Denna stomme blev billigast men har det största utsläppen av koldioxid från framställningen. Utfackningsväggen av KL-trä släppte ut minst koldioxid men blev det dyraste alternativet, utfackningsväggen av Paroc blev således det billigaste alternativet men släppte ut mest koldioxid av dessa två alternativ.
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Klemetz, Jacob, and Joseph Eklund. "Klimatpåverkan av stommaterial på Regnbågens förskola i Årjäng : Med fokus på koldioxidutsläpp vid val av KL-trästomme alternativt stålstomme med utfackningsväggar av trä och bjälklag av betong." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-78947.
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Idag förbrukas jordens resurser i högre takt än vad jorden klarar av att bearbeta. Byggbranschen tillhör en av de sektorer som har högst klimatpåverkan, främst i form av koldioxidutsläpp. Därför pågår ett kontinuerligt arbete med att ta fram byggnadsmaterial som skall minska belastningen på miljön. I byggbranschen kan man se en trend att korslimmat trä (KL-trä) blir allt mer efterfrågat som stommaterial. Det sägs ge upphov till mindre miljöpåverkan samt ge ett bättre inneklimat än vad andra stommaterial gör. Denna studie visar en teoretisk jämförelse av klimatpåverkan samt av inomhusmiljön mellan en KL-trästomme och en kombinerad stål- och betongstomme. Båda stomalternativen har projekterats av ByggDialog tillsammans med deras samarbetspartners. Referensbyggnaden är Regnbågens förskola i Årjängs kommun. Syftet med denna studie är att uppmärksamma, skapa en medvetenhet samt ge verktyg till ByggDialogs kunder för att göra ett klimatsmart stomval, vilket i sin tur också kan bidra till att de svenska hållbarhets målen uppnås till 2030. Klimatpåverkan beräknades under produktskedet vilket innebär råvaruförsörjning, transport och tillverkning för ingående material (modul A1-A3) med hjälp av ett Global Warming Potential-värde (GWP-värde). Vilket är ett värde på hur stor klimatpåverkan ett material ger upphov till i form av utsläpp av koldioxidekvivalenter. För att undersöka hur stomval påverkar inomhusmiljön gjordes en litteraturstudie. Resultatet visade att KL-trä som stommaterial gav upphov till cirka hälften så stor miljöpåverkan vad gäller koldioxidutsläpp men var cirka 12% dyrare att uppföra jämfört med en kombinerad stål- och betongstomme. Vid beräkning av koldioxidutsläpp per SEK visade det sig att en stomme av KL-trä hade cirka 67% lägre koldioxidutsläpp per SEK än vad en kombinerad stål- och betongstomme hade. Litteraturstudien visade att KL-trä som stommaterial gav en jämnare luftfuktighet men sämre värmelagringsförmåga och ljudabsorption i form av steg- och stomljud jämfört med en kombinerad stål- och betongstomme. Forskning visade att synligt trä till exempel KL-trä, ger en upplevelse av trygghet, avkoppling och allmänt välbehag för människor som vistas i byggnaden.<br>Today, the Earth's resources are used at a higher rate than the Earth can manage. The construction industry is one of the sectors that have the greatest negative climate impact, mainly related to high carbon dioxide emissions. This industry continuously strives to develop building- and construction materials resulting in an as low environmental footprint as possible. Recent trends, in the construction industry, shows an increase in the use of cross-limbed timber (CLT) for frame material. The claim is lower environmental footprint at the same time as it gives a better indoor climate compared to other frame materials. This study will be a theoretical comparison of the climate impact as well as the indoor environment between a CLT frame and a combined steel and concrete frame. Both frame alternatives have been designed by the construction company ByggDialog together with their partners. The reference building for this study is Regnbågens Preschool in Årjäng Municipality. The purpose of this study is to raise and create awareness and also provide tools for ByggDialog and their customers enabling a climate-smart frame selection. This will most likely also contribute to achieving the Swedish sustainability goals by 2030. By using data from the Global Warming Potential (GWP) for the input materials, the climate impact was calculated. Each construction frame type data was analyzed during the product phase which include raw material supply, transport and manufacturing (module A1-A3) in the form of emissions of carbon dioxide equivalents. A literature study was also conducted to analyze how a frame of CLT affects indoor environment. The result showed that by using a CLT frame material versus a combined steel and concrete-frame the environmental reduction was about 50% and about 12% increase in cost. When calculating the carbon dioxide emissions per SEK, it was found that the CLT frame construction had about 67% lower carbon dioxide emissions per SEK compared to a combined steel and concrete frame. The literature study showed that a frame material of CLT provides a more evenly distributed humidity, poorer heat storage capacity and less sound absorption capacity in the form of step- and frame sound compared to a combined steel and concrete frame construction. Further research in this field indicates that by having visible wood, for example a CLT frame provides an experience of safety, relaxation and general well-being for people in the building.
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Papanatsiou, Maria. "Stomatal clustering and hydrogen sulfide : unraveling novel aspects of stomatal behavior." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/6514/.
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Stomata are pores found on the epidermis of most aerial parts of plants and are formed by a specialized pair of cells, the guard cells. Stomata enable the uptake of CO2 in expense of water vapour release and therefore optimize the trade-off between transpirational water loss and carbon gain. Regulation of gas exchange is achieved by controlling the stomatal pore aperture involving the osmotic solute accumulation. Fluxes of K+ are mediated by the plasma membrane inward and outward rectifying K+ channels (KIN and KOUT), while the anion channels enable Cl- fluxes. Stomata in most plants follow the �one cell spacing rule� implying that the separation of stomata by at least one epidermal cell. However, there are several genera exhibiting stomata clusters, such as the genus Begonia. In this study I have used two Begonia species as well as Arabidopsis stomatal patterning mutants to explore the impact of stomatal clustering in plant physiology. In the tmm1 mutants the stomatal movements suppressed gas exchange responses when plants were exposed to light and darkness. Kinetic analysis of the K+ channels uncovered changes in the gating characteristics that affected the activity of KOUT channels as well as the voltage-dependence of KIN channel opening. Tail current analysis of K+ channels demonstrated that the effect was to reduce accumulation of K+ ions in the cytosol of guard cells from tmm1 plants. Raising light intensity and lowering evaporative demand enhanced WUE and growth of plants exhibiting single stomata, albeit the tmm1 mutant plants failed to respond likewise. Astonishingly, the tmm1 mutants were more resilient to prolonged drought stress via minimizing the transpirational water loss. Phenotypic analysis also revealed that the impaired stomatal behaviour of the tmm1 plants attenuated root growth under sucrose abundant conditions. I have also made use of the novel gasotransmitter hydrogen sulfide (H2S) to examine its effect on stomata. H2S-induced stomatal closure in both Arabidopsis and tobacco plants was dependent on the exclusive inhibition of KIN channels. The data implied a partial sensitivity of H2S effect to the intracellular Ca2+ levels, and modelling also suggest a role for pH in the H2S-mediate response. The tmm1 mutants did not respond to H2S in a wild type fashion, indicating that stomatal movements are altered irrespectively to the nature of stimuli. Collectively, my data suggest that stomatal spacing and their associations with neighbouring epidermal cells is important for the K+ relations of guard cells and their capacity to drive stomatal movements. The role of spacing was crucial for gaseous exchange as well as plant growth under favourable conditions. The data also provided novel insights into the network governing stomatal behaviour and positioned H2S to an independent branch of the ABA pathway. Finally, the data suggested an adaptive role for stomatal clustering under water-limited habitats and a potential use of H2S as a tool to minimize transpirational water loss.
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Saunders, Stephanie. "Living with a Stoma After Surgical Resection for Rectal Cancer: An Interpretive Phenomenological Study to Understand How Stomas Can Affect Physical Activity." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37308.
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The benefits of physical activity for cancer survivors are numerous and well-substantiated. However, it is unclear how to accommodate specific cancer treatments, such as a stoma as part of treatment for rectal cancer, in order to be physically active. To bridge this gap, this study undertook an interpretive phenomenological analysis to explore the experience of 15 rectal cancer survivors' engagement in physical activity with a stoma. Overall, three themes were found: 1) understanding the drive and the motivation to be physically active, 2) despite being motivated to be physically active with a stoma it can be challenging, and 3) how to be physically active with a stoma: lessons learned. The findings suggest rectal cancer survivors with a stoma require motivational support and enhanced competence and self-efficacy in order to engage in greater physical activity. Incorporating these skills into current information and supportive services targeting rectal cancer survivors with a stoma may help promote physical activity in this population.
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Aphalo, Pedro Jose. "Interactions in stomatal function." Thesis, University of Edinburgh, 1991. http://hdl.handle.net/1842/14758.
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(1) What is the relationship between stomatal responses and the rate of photosynthesis? The COa flux density and stomatal conductance are closely correlated, but there is not a simple causal link between them. This relationship is complex, and depends on both parallel but independent responses to light of stomata and photosynthesis, and indirect response of stomata mediated by photosynthesis. This indirect response occurs through CO2 depletion in the air spaces of the mesophyll and stomatal response to CO2- No evidence was found in favour of the proposed effect of photosynthesis on stomata through an unknown messenger. (2) What is the nature of the interaction between stomatal responses to humidity and temperature? The hypothesis that these responses are brought about by a single response to relative humidity at the leaf surface was tested, and shown to be incompatible with the responses of Hedera helix. It is suggested that the most appropriate variable for expressing humidity is, in this context, the water vapour deficit at the leaf surface. (3) What is the role of the boundary layer in the control of stomatal opening? Real world and simulation experiments were used to show that responses to bulk air vapour and COa mol fractions are both dependent on stomatal responses to CO2 and humidity. It is also shown that a feedforward response to humidity requires feedback through another variable for stability under natural conditions. Response to wind speed is due to changes in humidity and CO2 mol fraction at the leaf surface. (4) Are our current knowledge, and the resulting models, good enough for predicting short-term stomatal responses to changes in the environment? The need for a careful analysis of simulation models is stressed. Ball's empirical model of stomatal conductance was analysed. The original interpretation was found to be flawed, and a new one was proposed. The new interpretation views the model as a description of the relationship between COj flux rate and stomatal conductance, rather than of stomatal conductance alone. It is shown that this model is useful for describing the behaviour of the intercellular COj concentration. The model, was tested against data from the experiments. It was found that the responses to temperature and humidity are not treated in a satisfactory way. The response of the model to other variables is realistic. A modification to the model is described and tested. It is concluded that the model is a good starting point for the development of simulation models to be used as submodels in canopy and regional models.
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Amsbury, Samuel. "The composition and mechanical properties of the stomatal cell wall : implications for stomatal function." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/17245/.
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Denley, Bowers Rachel. "The economics of stomatal development." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22920/.
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Development is the result of a series of division, expansion and differentiation events, and the relationship between these events drives characteristics such as organ size and shape, patterning of tissues, and placement of specialised cells. Varying the rates of division, expansion and differentiation allows for plasticity in development. This plasticity means that there are often several routes to the same developmental outcome: for example, increasing cell division will increase the distance between specialised cells or increase organ size, and so will increasing cell expansion. Hence, a question arises: why do plants maintain a certain size or cell placement through a specific route, such as increasing cell expansion? The reason for this could be that one route is more energetically favourable than another, and so a calculation of economy is responsible for certain developmental decisions. Stomata are pores on the surface of the leaf which, in their opening and closing, regulate gas exchange and the movement of water vapour between the interior of the leaf and its environment. Stomatal development is a plastic developmental process which is governed by a series of specific cell division and differentiation events, and therefore provides a suitable model for exploring the relationship between changes in plastic developmental processes and energetic cost to the plant. The work described in this thesis uses a combination of experimental and theoretical methods to further understand the range of cell division, expansion and differentiation events which result in the spacing of stomata within the abaxial epidermis of the model plant Arabidopsis thaliana and the economic costs of those processes, to develop an understanding of the economics of stomatal development.
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Batta, Kucheli. "The role of guard cell chloroplasts in stomatal function and coordinating stomatal and mesophyll responses." Thesis, University of Essex, 2018. http://repository.essex.ac.uk/23447/.
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Guard cells controls the stomata through which exchange of gas takes place by balancing between CO2 uptake for photosynthesis and water loss through transpiration leading to ultimate plant water use efficiency (WUE). Climate change is predicted to lead to greater temperatures and reduced water availability resulting in adverse effect on plant productivity. Sustainable agriculture will therefore require a major reduction in plant water use hence stomata have become potential target for manipulation. Understanding the signal mechanisms of stomata in response to these changing environmental conditions is therefore critically important. In order to facilitate an understanding of stomatal regulation and how it is influenced by the surrounding mesophyll cells, we have used two approaches to find a possible coordination that links mesophyll and guard cell metabolism through the use of stomatal physiology and genetic engineering. The first approach used a novel epidermal mesophyll transfer experiment to monitor stomatal responses to dynamic environmental changes with and without the mesophyll present. The second approach used new molecular tools and techniques to manipulate chloroplast metabolism specifically in the guard cells to elucidate mesophyll-derived signals that coordinate mesophyll CO2 demands with stomatal behaviour towards crop improvement. The results presented have shown guard cells plays a role in stomatal function even though the degree of responsiveness is slower than when the mesophyll is present. Furthermore, the molecular approach demonstrated using Arabidopsis plants overexpressing Rieske and SBPase resulted in substantial and significant impacts on plant development coupled with increases in photosynthetic efficiency of photosystem II in the early stages of seedling development. The result obtained proves more opportunities await the exploitation of guard cells metabolism towards the improvement of plants.
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Parmar, Paroo. "Polyphosphoinositide metabolism in stomatal guard cells." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239043.
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Ries, Amber Beth. "Carbonic anhydrases function as mediators of CO₂-induced stomatal movements and regulators of stomatal development in Arabidopsis thaliana." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p1467784.
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Thesis (M.S.)--University of California, San Diego, 2009.<br>Title from first page of PDF file (viewed September 15, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 58-61).
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Ramic, Zlatan, and Kawa Eliassi. "Snedställningskrafters påverkan på prefabricerade pelar-balk stommar." Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-15751.
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Mellstrand, Caroline. "Rationell produktion av platsgjutna stommar för flerbostadshus." Thesis, KTH, Byggnadsteknik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-35040.
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van, Gardingen Paul R. "Environmental and stomatal physiology of Nothofagus seedlings." Thesis, University of Canterbury. Botany, 1987. http://hdl.handle.net/10092/7573.
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The Maruia Valley on the West Coast of the South Island of New Zealand is a region with Nothofagus forest dominated by mixtures of N. fusca and N. menziesii. The Station Creek area was selected for environmental and gas exchange measurements with the two species.
The mean daily temperature and vapour pressure deficit (VPD) variation was found to be up to two times higher on an open logged site than under both closed canopy and a small canopy gap. The light flux under closed canopy gap was 5% of that gap measured in the open. During summer the light flux under the canopy gap was up to 25% of that in the open.
Gas exchange was measured using a LI-COR LI-6000 portable photosynthesis system. An improved set of formulae were developed for this system and have been implemented in a computer programme for the IBM PC and compatibles.
Gas exchange measurements at Station Creek were used to determine the maximum rates of photosynthesis (Amax) and stomatal conductance (gmax) as well as the sensitivity of these estimates to VPD. The rates of gas exchange were higher in N. menziesii than N. fusea. No significant difference was found between species for the estimates of stomatal and photosynthetic sensitivity. In addition there was no difference between foliage growing in the open, under a canopy gap, or under closed canopy.
Gas exchange measurements of saplings growing in a nursery at Rangiora on the east coast of the South Island gave similar results during early summer. As the season progressed, the rates were lower at Rangiora due to moderate water stress.
It is suggested that Nothofagus seedlings have a wide ecological tolerance, which is in part due to the generalized stomatal response to VPD. This can explain how Nothofagus is capable of regenerating under a wide range of environmental conditions. Under extreme environments seedling growth is reduced and regeneration will succeed only in the absence of rapidly growing competing species.
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Metcalfe, Michelle J. "Monitoring environmental features using leaf stomatal characteristics." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4698/.
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It is recognised that atmospheric CO(_2) concentrations are increasing, with concerns raised as to the global impact continued rises may have. Plant stomatal parameters have been suggested as a means of monitoring changing CO(_2) levels. In order to assess their suitability for use, a thorough examination of leaf characteristics within a variety of surroundings was undertaken. Environments examined included both natural variations in CO(_2), which incorporated a variety of environmental influences and artificially enhanced ones where it was possible to monitor specific responses to variable CO(_2) levels. A short term study of Ranunculus ficaria, Sambucus nigra and Hedera helix revealed considerable variation in stomatal parameters, with inconsistent responses observed between and within species. These variations could not be attributed to CO(_2) changes and were assigned to a combination of other factors. R. ficaria grown in an artificial environment at ambient and elevated CO(_2) produced significant and consistent changes in stomatal parameters. Stomatal density and index were found to be reduced at elevated CO(_2) concentrations, with a decrease in guard cell dimensions. Salix herbacea, growing along a naturally reduced CO(_2) partial pressure gradient further highlighted the extent of variation in stomatal parameters in extant material within a species. No consistent stomatal trends associated with changing CO(_2) levels were observed. This inherent variation must be considered before any conclusions can be made regarding stomatal parameters obtained from fossil material. The novel application of molecular biology techniques to identify S. herbacea leaves was partially successful. However, identification of leaf macrofossils was not possible, due to the inferior preservation of DNA. However, the technique will provide a useful tool for identification if suitably preserved macrofossil fragments were available. S. herbacea leaf macrofossils revealed no consistent correlation to past changes in CO(_2) levels. The use of as an additional tool with which to monitor environmental change once again showed variation, and was not associated closely with changes in CO(_2) levels or stomatal parameters. In light of this work it would appear that the use of stomatal parameters is of limited value as a model to monitor environmental change, in the absence of information concerning other variables, and as such must be treated with caution.
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Nichols, K. J. "The influence of bentazone on stomatal movements." Thesis, Nottingham Trent University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233906.
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Buckenham, A. H. "Effects of sulphur dioxide on stomatal functioning." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378436.
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Lee, Joonsang. "Influence of the mesophyll on stomatal opening." Thesis, University of Aberdeen, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314415.
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This study shows that stomata in the isolated epidermis do not behave like those in the intact leaf and that the mesophyll plays an important role in the mechanism of stomatal opening over short periods. The results suggested that the opening of stomata in isolated epidermis was inferior to that in the intact leaf and was influenced by the concentration of KCl in the medium rather than by light. Stomatal opening in isolated epidermis of <i>Commelina</i> was not only insensitive to light but also unaffected by CO<sub>2</sub> in the medium containing 100 mol m<sup>-3</sup> KCl. The absence of an effect of light and CO<sub>2</sub> on the stomata in isolated epidermis and the evidence that they possessed the potential of those in the intact leaf to open wide, suggested that the mesophyll could be important in influencing stomatal opening in the intact leaf. The solution in which the mesophyll cells were incubated was separated by centrifugation. The medium from cells previously incubated in the light caused the stomata in the isolated epidermis to open but that from cells kept in the dark had no effect. Thus the stimulatory influence of the mesophyll cells in bringing about stomatal opening could be separated from the cells into solution. For ease of description it is tentatively suggested that the putative factor which promotes stomatal opening indicated by the results be called stomatin. Stomatin will be produced when the chloroplasts in the mesophyll are exposed to white light.
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Dutton, Christian. "Interactions between stomatal density and plant disease." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22749/.
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Jiang, Kun. "Identifying novel stomatal signalling components in Arabidopis thaliana." Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504233.
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The role of actin cytoskeleton reorganisation in mediating Arabidopsis stomatal movement has been established for a decade. However, the signalling machinery facilitating actin reorganisation in response to environmental stimuli remains largely unknown. This study demonstrates that the actin-related protein-2/3 (ARP2/3) complex plays a pivotal role in coupling external signal perception to downstream actin dynamics. A mutation in HSR3, which is allelic to the gene encoding the lRPC2 subunit of the ARP2/3 complex, confers stomatal insensitivity to a range of external stimuli such as light/dark transition, abscisic acid and CaCl2. RT-PCR malysis of guard cell-enriched RNA suggests that HSR3 is expressed in guard cells.
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Evans, N. H. "Responses of stomatal guard cells to methyl jasmonate." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598902.
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Previous studies had indicated that the jasmonate family of plant growth regulators (PGR's) might promote stomatal closure, although the mechanistic basis of any effect was not determined. In this study, patch-clamp electrophysiology was used to examine potassium transport across the plasma-membrane of <I>Vicia faba </I>guard cell protoplasts and demonstrated methyl jasmonate (Me-JA) has concentration-dependent effects on transport. At 0.1 μM, Me-JA reduced the conductance of the inward-rectifying potassium channel and increased the conductance of the outward-rectifying potassium channel. This would facilitate the efflux of potassium from the guard cell cytoplasm and a loss of guard cell turgor, indicating how Me-JA might act to promote stomatal closure. In radioactive flux studies, Me-JA promoted the efflux of vacuolar <SUP>86</SUP>Rb<SUP>+</SUP> from <I>Commelina communis </I>guard cells, suggesting it had the ability to mobilise K<SUP>+</SUP> from the major ion store in the turgid guard cell. The results of bioassay experiments supported the conclusions drawn from patch-clamp and radioactive flux work, demonstrating that Me-JA could act to promote stomatal closure in <I>C. communis</I> epidermal peels. In patch-clamp, radioactive flux and bioassay studies, the frequency and magnitude of the Me-JA response varied considerably, suggesting it may have been dependent upon the physiological address of the guard cells. Calcium buffering failed to eliminate Me-JA-induced changes in plasma-membrane K<SUP>+</SUP> channel conductance but nicotinamide inhibited the vacuolar efflux response, suggesting the Me-JA signal is relayed to the tonoplast via a calcium-dependent mechanism.
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Aitken, Fiona Louise. "Phosphoinositide signal transduction genes from stomatal guard cells." Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310758.
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Kutter, Claudia. "MicroRNA-mediated regulation of stomatal development in arabidopsis /." Basel : [s.n.], 2007. http://edoc.unibas.ch/diss/DissB_8055.
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Smyth, Wendy Dawn. "Regulation of ion channels in stomatal guard cells." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621992.
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Ballard, Trevor R. "Blue and Red Light Effects on Stomatal Oscillations." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7393.
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Plants absorb CO2 through pores in their leaves called stomata, which are known to open and close in response to myriad environmental and physiological triggers. We demonstrate that blue light inhibits stomatal aperture oscillations in both the guard cells and surrounding tissue layers, whereas these oscillations continue under the influence of red light. This observation of blue light behavior agrees with recent research and suggests another physiological pathway for oscillations.
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Wood, Julian Lawrence. "The role of pH signalling in stomatal responses." Thesis, University of Oxford, 1996. https://ora.ox.ac.uk/objects/uuid:e97ed751-5a06-4bc7-9a48-d09b8a93d9a8.
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The role of cytoplasmic pH in guard cell signal transduction was investigated in epidermal strips of Commelina communis. The cytoplasmic pH of guard cells was measured by dual excitation ratio confocal laser scanning microscopy. Large transient alkalinisations occurred for up to 20 minutes both during closure, in response to ABA and calcium, and opening in response to IAA and fusicoccin. Therefore the direction of the pH change does not determine the direction stomatal movement in Commelina communis in contrast to previous reports in Paphiopedilum tonsum. Furthermore, CO<sub>2</sub> caused a slow acidification during stomatal closure, indicating that pore movements are not always associated with a transient cytoplasmic alkalinisation. The internal pH of guard cells was buffered by low concentrations of isobutyrate. Small reductions in stomatal closure in response to ABA and calcium were observed, however, responses to CO<sub>2</sub>, IAA and fusicoccin were unaltered. High levels of isobutyrate stimulated wide stomatal opening for all stimuli. Therefore manipulation of cytoplasmic pH only give limited support in the case of ABA and calcium that cytoplasmic pH changes are either necessary for or modulate stomatal movements. The observed pH changes may therefore be a consequence of the mechanism underlying pore movement rather than genuine cytoplasmic signals per se, A model is described based on strong ion and weak acid chemistry which predicts that the observed pH transients result from changes in the concentrations of chloride and malate which charge balance the potassium fluxes during stomatal movements. No suitable fluorescent indicator was found to measure pH in either the apoplast or vacuole. However the volume of the guard cell lumen, vacuole, nucleus and chloroplast were directly measured during stomatal movements and the cytoplasmic volume was calculated. These volumes were used to re-calculate compartmental pH and ion concentrations from previous reports.
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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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Liu, Xuguang. "The Arabidopsis MYB FOUR LIPS conditionally restricts stomatal endoreduplication." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/30886.
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Stomata are two-celled epidermal valves responsible for gas exchange between the shoot and the atmosphere. FOUR LIPS and MYB88 are MYB transcription factors required for correctly patterning Arabidopsis stomata. Normally the guard mother cell (GMC), a stomatal precursor cell, divides once symmetrically producing a two-celled stoma. However, when FLP function is lost via mutation, excess divisions occur which result in abnormally two (or more) stomata in direct contact. Thus FLP normally represses cell divisions allowing normal stomatal differentiation and patterning. The last division in normal stomatal development, as well as the excess divisions in flp mutants, require the activities of CYCLIN DEPENDENT KINASE B1;1 and CDKB1;2. This study reports that the loss of function of all four genes (i.e. in a flp-1 myb88 cdkb1;1 cdkb1;2 quadruple mutant) induces a novel phenotype of endoreduplicated stomata and single guard cells, which are much larger than normal. In addition, chemically blocking mitosis in the flp-1 mutant or flp-1 myb88 double mutant, as opposed to in the quadruple mutant, also induces the formation of endoreduplicated stomata and single guard cells. These data suggest that the genetic or chemical blockage of mitosis allows the loss of FLP function, which normally limits division, to instead derepress endoreplication. FLP directly targets and likely represses the expression of a series of core cell cycle genes including those that act during G1-to-S phase (such as CELL DIVISION CONTROL 6A which promotes DNA replication) and G2-to-M phase (such as CDKB1;1 which promotes mitosis). These data extend previous results showing that FLP is a developmental regulator that coordinates cell cycle and differentiation.
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Montgomery, Lucy Theresa. "Investigations of ABA signalling pathways in stomatal guard cells." Thesis, Lancaster University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242895.
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Odapalli, Nalini. "CONTROL OF STOMATAL FORMATION IN ARABIDOPSIS THALIANA INFLORESCENCE STEM." Master's thesis, University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2758.
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Stomata are cellular structures that control water loss and gas exchange through the plant epidermis. Stomata arise from special stem cells called meristemoids through a series of programmed asymmetric divisions that are controlled by cell signaling, or via multitude of regulatory pathways and intercellular communication between epidermal cells. In Arabidopsis thaliana, stomata are spaced non-randomly in the epidermis by cell-cell signaling of the receptor-like protein TOO MANY MOUTHS (TMM) as well as other proteins. Point mutation of the TMM gene prevents the development of stomata in some tissues like inflorescence stems. Investigation of tmm mutant stems showed that self-renewing stem cell-like precursors form by dividing asymmetrically but fail to form stomata. This is further supported by molecular markers of stomatal cell fate that show stomatal precursors form but do not differentiate as stomata. Therefore, TMM signaling is likely required to control expression of genes that are essential for the formation of stomata in stems. As a second approach, gene expression profiling was used to identify candidate genes involved in stomatal biogenesis. Differentially expressed genes were categorized by gene ontology and analyzed for statistically overrepresented classes to gain insight into functional processes. Comparison of stem expression data with previously published microarray data was used to narrow the list to genes involved in stomatal patterning. Mutants in these target genes have been obtained and phenotypic analysis revealed new stomatal regulators. Comparison of epidermal cells of the stem tip region from wild-type and tmm revealed that there are significantly more meristemoids formed in tmm stems compared to wild-type stems. In addition, the orientation of meristemoids formed in wild-type stems was random with respect to stem polarity and followed a spiral pattern of asymmetric divisions similar to leaves. This showed that stomatal patterning in dicots does not follow orientation in asymmetric cell division for spacing the adjacent stomata like monocots.<br>M.S.<br>Department of Biology<br>Sciences<br>Biology MS
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Wilhoite, David, Tyler D. O. Aasen, and Lawrence M. D. Schmidt. "Life threatening GI bleeding from stomal varices managed by TIPS and Amplatzer plug embolization." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/asrf/2018/schedule/73.
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Stomal varices are a rare phenomenon that can infrequently develop in patients with enterostomies and portal hypertension. Acute gastrointestinal bleeding from stomal varices can be life threatening and is often a diagnostic challenge. We present a case of severe gastrointestinal hemorrhage from stomal varices requiring emergent intervention with transjugular intrahepatic portosystemic shunt (TIPS) and plug embolization.
A 61 year old male patient with a history of colorectal adenocarcinoma status post chemotherapy, radiation, along with low anterior colon resection with ostomy creation presented with a one day history of sudden onset of bright red blood from his colostomy site. He had a known history of decompensated cirrhosis related to hepatitis C and alcohol abuse. On arrival, the patient was tachycardic with borderline low blood pressure with evidence of bright red bleeding from his ostomy site. After initial resuscitation, a colonoscopy through the stoma revealed active bleeding from what appeared to be submucosal colonic varices. The patient continued to experience large volumes of blood loss and became more hemodynamically unstable. Cross sectional imaging showed colonic varices being fed by a branch of the inferior mesenteric vein. The patient underwent TIPS followed by Amplatzer plug embolization of the branch of the interior mesenteric vein that was feeding the colonic stomal varices. The patient’s bleeding was stopped by the combination of these therapeutic modalities and he recovered without complication.
The current standard of care for treatment of such varices is with either (1) local therapy with ligation or sclerotherapy, (2) surgical interventions such as stomal manipulation or vessel shunting, either transhepatic or portosystemic to reduce portal pressures, or (3) liver transplantation. Our patient required an unusual combination of TIPS and Amplatzer plug embolization to control his massive hemorrhage. This combination of therapies has been shown effective for the management of select cases of esophageal or gastric variceal bleeding; however, our case demonstrates that the application of the TIPS plus Amplatzer plug embolization can be applied more broadly to the rare scenario of colonic stomal varices.
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Parsons, Andrew. "Calcium signalling in guard cells of intact Arabidopsis thaliana plants : investigations using transgenic techniques." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365333.
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Lucas, Jessica Regan. "Microtubule arrays and cell divisions of stomatal development in Arabidopsis." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1181759887.
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Metcalf, Jessica Lynne. "Conservation genetics of the greenback cutthroat trout (Oncorhynchus clarkii stomias)." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3273821.
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Osman, Mohamoud, Albert Dobrenz, Haile Tewolde, and Robert Voigt. "Stomatal Response to Water Stress in Two Pearl Millet Genotypes." College of Agriculture, University of Arizona (Tucson, AZ), 1987. http://hdl.handle.net/10150/203813.
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A study was conducted in the field to test whether stomatal sensitivity to water stress can be used as a selection criterion for drought tolerance in two pearl millet genotypes. In both cultivars, stomatal aperture was significantly reduced by the water stress. However, the proportion of reduction per 20 mm decrease in applied water was much higher for the hybrid than for the female parent. This is clearly an indication of a higher stomatal sensitivity in the hybrid, which probably explains the superior performance under water stress that was previously observed in this genotype.
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Funk, Kevin A. "Stomatal stem cell regulation by a novel protein in Arabidopsis." Honors in the Major Thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1260.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.<br>Bachelors<br>Sciences<br>Biology
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Liu, Lumin. "Stomatal and leaf growth responses to water deficit in willow." Thesis, University of Aberdeen, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297564.
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Abscisic acid (ABA) was synthesised in dehydrating leaves and roots of willow (<I>Salix dasyclados</I>) and exogenous ABA in the xylem stream was shown to cause decreases in stomatal conductance. A transient decrease in leaf water potential occurred if water was entirely withheld from roots on one side of a willow plant. This was avoided if roots from all sides of the plant were watered and only root tips were allowed to dehydrate. Partial stomatal closure and decreased leaf extension rate then occurred without any initial perturbation in leaf water potential or leaf ABA. The drying event was associated with an increased content of ABA in root tips and xylem sap. The effects were reversible on either rewatering or excision of the affected root tips. It was concluded that partial dehydration of root tips caused partial stomatal closure and decreased leaf extension, and that changes in the ABA content of root tips and the xylem sap were consistent with a possible causal role for root-sourced ABA in the regulation of leaf physiology in response to root water deficit. Stem-girdling experiments indicated that a major pathway of ABA transport, between leaves on different stems in the shoot system, was in the phloem, without an apparent involvement of transport in the xylem. Damage to the shoot apex caused an increase in stomatal conductance. This was associated with a decreased content of ABA in the xylem sap and in fully extended leaves. It is suggested that these changes may have been associated with a possible import of ABA from mature leaves into the growth sites of axillary shoots. Results are discussed within the context of water deficit and the growth and survival of individual stems in a willow plantation.
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Lan, Jue. "The role and regulation of triacylgycerol breakdown in stomatal opening." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.730836.
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Lan, Jue. "The role and regulation of triacylglycerol breakdown in stomatal opening." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.742980.
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Chireshe, Nyaradzo. "Stomatal control during dessication in the resurrection plant Xerophyta humilis." Bachelor's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/24964.
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Stomatal apertures on leaves of the resurrection plant Xerophyta humilis were monitored microscopically in order to characterize stomatal regulation during a dehydration time course. In addition, the effect of exogenous application of the stress hormone ABA on stomatal regulation was followed. X humilis stomatal regulation appears to be initially similar to that typical of desiccation sensitive plants, but differed in that stomata did not all close at once but at a slower rate to control the drying rate of the plant, this gave time for protection mechanisms to be laid down. The signal hormone ABA was found to have strong stomatal control on the adaxial surfaces of leaves but weak control on the abaxial leaf surfaces, thus it is difficult to say that ABA regulates the process until RWC of below 50%, where stomatal apertures open as a result of shrinkage of guard cells due to loss of water.
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Beguerisse, Diaz Mariano. "Mathematical modelling of integrated signalling networks in stomatal guard cells." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9677.
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Stomata are tiny pores in plant leaves that regulate gas and water exchange between plants and their environment. Abscisic acid and ethylene are two well-known elicitors of stomatal closure. Yet when stomata are presented with a combination of both signals, they fail to close; these observations are hard to reconcile biologically and their explanation is not easily obtained by experimental means alone. To shed light on this unexplained behaviour, a combination of mathematical, computational, and experimental techniques are used. A differential equation model of stomatal closure is constructed from known biochemical interactions; this modelling process has motivated the collection of experimental measurements of components in the pathway, at time points beyond what is usually found in the literature. The experimental observations include stomatal aperture and hydrogen peroxide production in Arabidopsis thaliana guard cells treated with abscisic acid, ethylene, and a combination of both. These measurements show that sustained high levels of hydrogen peroxide are required to achieve stomatal closure and that guard cells exhibit increased antioxidant activity when treated with a combined dose of abscisic acid and ethylene. Additionally, the experimental observations and modelling suggest a distinct role for two antioxidant mechanisms during stomatal closure: a slower, delayed response that is activated by a single stimulus (abscisic acid or ethylene) and another more rapid mechanism that is only activated when both stimuli are present. The model indicates that the presence of this ‘and’ mechanism in the antioxidant response is crucial to explain the lack of closure under a combined stimulus. Estimating parameters from data is a key stage of the modelling process, particularly in models of biological systems many parameters need to be estimated from sparse and noisy data sets, such is the case of the stomatal closure model presented here. Over the years, a variety of heuristics have been proposed to solve this complex optimisation problem, with good results in some cases yet with limitations in the biological setting. In this thesis, an algorithm for model parameter fitting is developed combining ideas from evolutionary algorithms, sequential Monte Carlo methods and direct search optimisation. The method is shown to perform well even when the order of magnitude and/or the range of the parameters is unknown. The method refines iteratively a sequence of parameter distributions through local optimisation combined with partial resampling from a historical prior defined over the support of all previous iterations. The method is tested on biological models using both simulated and real experimental data, and it estimates the parameters efficiently even in the absence of a priori knowledge about the parameters. Then, this method is used to find the parameter values of the much larger stomatal closure model from experimental observations. A classic model of linear activation cascades is studied in this thesis. In a special but important case the output of an entire cascade can be represented analytically as a function of the input and a lower incomplete gamma function. If the inactivation rate of any component is altered, the change induced at the output is independent of the position in the cascade of the modified component. These analytical results show how one can reduce the number of equations and parameters in ODE models of cell signalling cascades, and how delay differential equation models can sometimes be approximated through the use of simple expressions involving the incomplete gamma function. The expressions with the lower incomplete gamma functions are used in the construction of the model of stomatal closure to represent the activation dynamics of the antioxidant mechanisms in guard cells. Fitting the stomatal closure model parameters to the data indicates that the antioxidant responses should have two different timescales, which can explain the lack of closure under a combined ABA and ethylene stimulus.
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Movahedi, Mahsa. "Identifying stomatal signalling genes to improve plant water use efficiency." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4539/.
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Water is lost from higher plants via transpiration through stomatal pores the aperture of which is regulated by pairs of guard cells. Genetic engineering of the guard cell abscisic acid (ABA) signalling network that induces stomatal closure under drought stress is a key target for improving crop water use efficiency. In this study experiments were designed to investigate whether the biochemical mechanisms associated with the N-end rule pathway of targeted proteolysis could be involved in the regulation of stomatal apertures. The results indicate that the gene encoding the plant N-recognin, PRT6 (PROTEOLYSIS6), and the N-end rule pathway, are important in regulating stomatal ABA-responses in addition to their previously described roles in germination and hypoxia. Direct measurements of stomatal apertures showed that plants lacking PRT6 exhibit hypersensitive stomatal closure in response to ABA, and IR thermal imaging revealed reduced evapotranspiration under drought-stress. Together with a reduction in stomatal density, these properties result in drought tolerant plants. Plants lacking PRT6 are able to synthesis NO but their stomata do not close in response to NO suggesting that PRT6 is required for stomatal aperture responses to NO. Double mutant studies suggested that PRT6 (and by implication the N-end rule pathway) genetically interacts with known guard cell ABA signalling components OST1 and ABI1, and that it may act either downstream in the same signalling pathway or in an independent pathway. Several other enzymatic components of the plant N-end rule pathway were also shown to be involved in controlling stomatal ABA sensitivity including arginyl transferase and methionine amino peptidase activities. These results indicate that at least one of the N-end rule protein substrates which mediates ABA sensitivity has a methionine-cysteine motif at its N-terminus. A separate set of experiments were designed to investigate whether stomatal ABA-signalling pathways could have been conserved throughout land plant evolution. Cross-genetic complementation experiments were carried out to determine whether Physcomitrella stomatal apertures are able to respond to ABA and CO2 using a similar signalling pathway to that of flowering plants. The results demonstrated involvement of OST1 and ABI1 orthologues indicating that the stomata of the moss respond to ABA and CO2 using a signalling pathway that appears to be directly comparable to that of the model flowering plant Arabidopsis thaliana.
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Doheny-Adams, Timothy. "Manipulating stomatal density affects plant growth, yield and drought tolerance." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4180/.
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Photosynthesis in leaves is dependent on CO2 reaching mesophyll cells which contain the bulk of chlorophyll, yet most of the leaf is enveloped by a waxy cuticle which is almost impermeable to CO2 and water. Gas exchange is enabled through pores on the leaf epidermis called stomata which are each formed by two specialised guard cells morphologically distinct from general epidermal cells and able to react to their environment by increasing or decreasing cell turgor. This enables the stomatal pores to open or close depending on the plant’s need to acquire CO2 or conserve water, allowing much needed flexibility in plant water relations. The experiments detailed in this thesis have the broad aim of determining correlations between altered stomatal density, stomatal size, leaf gas exchange, drought tolerance, and plant water use efficiency. Most experiments have been carried out on a set of Arabidopsis mutants with altered expression of Epidermal Patterning Factors (EPFs), a peptide family which is involved in the development of stomatal patterning and density on the leaf. Chapter 3 addresses the question of how altering the EPF family of peptides affects leaf morphology and more specifically whether stomatal densities correlate with stomatal size in Arabidopsis plants with altered EPF expression patterns. Chapter 4 examines the leaf gas exchange properties of Arabidopsis and questions whether or not altering stomatal density impacts leaf water use efficiency and photosynthesis. Finally, experiments in chapter 5 highlight how combined changes to leaf morphology and gas exchange due to altered EPF expression impact drought tolerance, seed yield and rosette morphology. Although most of this work was carried out on Arabidopsis plants, stomatal densities and water use efficiencies were also examined in a set of Barley cultivars to determine whether similar trends could be observed in a directly agriculturally useful plant. Results of these experiments and suggested directions to pursue this work in barley are summarised in chapter 6.
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Jose, Sarah Bryallen. "Investigating the link between cuticular wax biosynthesis and stomatal development." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715839.
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Saladžinskas, Žilvinas. "Kvalifikuotos ir kokybiškos pagalbos stomuotiems pacientams organizavimo problemos stacionarinėse asmens sveikatos priežiūros įstaigose." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050616_121644-36326.
Full textAbstract:
Qualified assistance for stoma patients in Lithuania is insufficient. Failure to provide preoperative information to patients results in not only physical, but also psychological trauma, which negatively affects the patients’ postoperative quality of life. Physicians and nurses have insufficient information about stoma care. In Lithuania, there have been no studies that would evaluate the organization of assistance for stoma patients.
The aim of the performed study was to identify the drawbacks in the assistance for stoma patients in hospitals, and to propose measures for the elimination of these drawbacks.
Methods and results. During the study, several investigations were performed, including questionnaire-based inquiry of patients for the evaluation of their post-operative quality of life following stoma formation, and the inquiry of patients for the comparison of the importance of preoperative and postoperative training on stoma care. The inquiry was performed using standardized quality of life questionnaires EORTC QLQ-C30 (version 3), EORTC QLQ-CR38, and additional questionnaires aimed at the evaluation of the convenience of the stoma site and the influence of preoperative and postoperative training on the quality of life during the distant postoperative period. For the second inquiry, three groups of subjects were formed. The first group included patients in whom optimal site of the stoma was selected before the operation, who were provided with full information on... [to full text]
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Ferrero-Serrano, Angel. "Stomal densities in Arabidopsis thaliana : physiology, growth and inter-genotypic interactions in relation to water availability." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539563.
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Matsumoto, Kazuho, Takeshi Ohta, and Takafumi Tanaka. "Dependence of stomatal conductance on leaf chlorophyll concentration and meteorological variables." Elsevier, 2005. http://hdl.handle.net/2237/6964.
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Pepin, Steeve. "Stomatal control of whole-plant photosynthesis and transpiration in conifer seedlings." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ36648.pdf.
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Robinson, Michael Frederick. "Sodium-induced stomatal closure in the maritime halophyte Aster tripolium (L.)." Thesis, Lancaster University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337555.
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