Siga este link para ver outros tipos de publicações sobre o tema: Photosynthetic.
Teses / dissertações sobre o tema "Photosynthetic"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 50 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Photosynthetic".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja as teses / dissertações das mais diversas áreas científicas e compile uma bibliografia correta.
1
Forrest, Mary Elspet. "Studies on the transcription of photosynthesis genes of the photosynthetic bacterium Rhodobacter capsulatus". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28778.
Texto completo da fonteResumo:
Rhodobacter capsulatus is a Gram negative bacterium that exhibits a variety of growth modes, including chemoheterotrophic growth and photoheterotrophic growth. Upon a shift of cultures from high to low oxygen concentrations the photosynthetic apparatus is synthesized and incorporated into the inner membrane. The puf operon contains genes that encode structural proteins found in the light-harvesting and reaction center complexes. In a preliminary attempt to pinpoint the location of the puf promoter R. capsulatus RNA polymerase was purified by standard techniques and used in in vitro runoff
transcription assays. It was found that the polymerase was capable of specific transcription with linearized pUC13 DNA but no specific transcription could be obtained with K capsulatus DNA. It was concluded that some factor or condition necessary for specific transcription with R capsulatus DNA was absent from these assays. The location of the puf promoter was subsequently found through a series of deletions and oligonucleotide-directed mutations in the 5' region of the puf operon. Fragments that contained these mutations were placed translationally in-frame with the lacZ gene of Escherichia coli in plasmids that could be conjugated into K capsulatus. Assays of beta-galactosidase activities under low and high oxygen conditions resulted in localization of the promoter to a position approximately 540 basepairs upstream of what was previously believed to be the first gene of the operon, the pufB gene. RNA 5' end-mapping experiments showed that the quantity of RNA transcripts obtained were comparable to the lacZ activities. The existence of multiple low abundance RNA 5' ends prompted the theory that the primary transcript has a short half-life, and is rapidly processed to yield a more stable transcript with a 5' end that maps just upstream of the pufB gene. It was found that only the 5' end nearest to the promoter could be capped by guanylyl transferase, and this could only be detected when the putative processing sites were deleted. The DNA sequence between the promoter and the pufB gene contains a new gene of the puf operon, the pufO gene. Deletion of this gene showed that it plays an essential role in the formation of mature light-harvesting and reaction center complexes.Science, Faculty of
Microbiology and Immunology, Department of
Graduate
2
Tan, Swee Ching. "Photosynthetic proteins photovoltaic devices". Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609050.
Texto completo da fonte
3
Bibby, T. S. "Photosynthetic complexes of cyanobacteria". Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595520.
Texto completo da fonte
4
Tomeo, Nicholas J. "Genetic Variation in Photosynthesis as a Tool for Finding Principal Routes to Enhancing Photosynthetic Efficiency". Ohio University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1492185865465393.
Texto completo da fonte
5
Channa, Aravinda Wijesinghe W. M. "Photosynthetic antenna-reaction-center mimicry". Diss., Wichita State University, 2012. http://hdl.handle.net/10057/5369.
Texto completo da fonteResumo:
The research presented in this dissertation discusses the mimicry of primary events in natural photosynthesis via artificial molecular constructs. Photosynthesis involves two major steps, absorption of light by antenna pigments and transfer of the excitation energy to the reaction center where charge separated entities are formed via photoinduced electron transfer (PET).
The synthesized artificial molecular systems are comprisedof porphyrin-fullerene, donor-acceptor entities due to their well studied photophysical properties which are essential to yield long-lived charge-separated states. Covalent and non covalent binding strategies have been employed in the design and synthesis of these novel artificial antenna-reaction centers.
The synthesized molecular systems are characterized using standard spectroscopic techniques. Their properties and performances in terms of an artificial photosynthetic model are evaluated by electrochemical, computational, time resolved emission, and transient absorption spectral studies. The systems studied reveal their potential in transferring excitation energy and yielding long-lived charge separated states with fast charge separation and slow charge recombination. The photoelectrochemistry of some of the compounds reveal their ability to convert light into electricity. Some triads show better performance as dyes in dye sensitized solar cells giving around 12% IPCE, incident photon-to-photocurrent conversion efficiency.Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Chemistry
6
Nandha, Beena. "Regulation of photosynthetic electron transport". Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502263.
Texto completo da fonteResumo:
Investigations in this thesis aimed to understand the mechanisms that regulate the photosynthetic electron transport chain in C3 plants and therefore also the significance of cyclic electron flow (CEF). Physiological analysis of Arabidopsis thaliana photosynthetic pgr5 mutant, which had previously been reported to be a CEF mutant, were undertaken. The reduced state of P700 in the light meant that standard assays for P700 and CEF, using P700 absorbance could not be applied. Design and development of flash spectrophotometric techniques were necessary. This primarily involved P700 oxidation kinetics at 820 nm combined with the electrochromic shift at 520 nm to measure electrical field generation.
7
Beanland, Timothy James. "The phylogeny of photosynthetic organisms". Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385339.
Texto completo da fonte
8
Horken, Kempton M. "Isolation of photosynthetic membranes and submembranous particles from the cyanobacterium synechococcus PCC 7942". Virtual Press, 1996. http://liblink.bsu.edu/uhtbin/catkey/1036184.
Texto completo da fonteResumo:
Photosynthetic membranes were prepared from the cyanobacterium Synechococcus PCC 7942 with oxygen evolving specific activity of 250-300 µmoles 02/ mg chl/hr. The membranes retained activity with a half-life of 4-5 days when stored at 0°C, or when quickly frozen in liquid nitrogen, greater than 95% of the activity remained after 2 months. Attempts to purify homogeneous preparations of photosystem II complexes from these membranes by detergent extraction were unsuccessful as indicated by a lack of a significant increase in oxygen evolution specific activity of the detergent extracts. Photosynthetic membrane detergent extracts usually maintained the same oxygen evolution specific activity as the orginal membranes, and a considerable amount of Photosystem I activity (75 µmoles 02 consumed /mg chl/hr in the Mehler reaction) was still present. The donor side of the photosystem II particles in the detergent extract was intact since the artificial electron acceptor, 2,6-dichiorophenolindophenol (DCPIP), was reduced at a rate comparable to the oxygen evolving activity. All oxygen evolving activity of the detergent extracts was lost when ion-exchange chromatography was used to resolve the co-extracted photosystem II and photosystem I complexes.Department of Biology
9
Zilsel, Joanna. "Studies on inter-species expression of photosynthesis genes in Rhodobacter capsulatus". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29902.
Texto completo da fonteResumo:
The primary amino acid sequences of the L, M, and H photosynthetic reaction center peptide subunits from a number of purple non-sulfur bacteria, including Rhodopseudomonas viridis, Rhodobacter sphaeroides, and Rhodobacter capsulatus have been previously shown to be highly homologous, and detailed X-ray crystallographic analyses of reaction centers from two species of purple non-sulfur bacteria, Rps. viridis and R. sphaeroides have shown that all recognized structural and functional features are conserved. Experiments were undertaken to determine whether genes encoding reaction center and light harvesting peptide subunits from one species could be functionally expressed in other species. Plasmid-borne copies of R sphaeroides and Rps. viridis pigment binding-peptide genes were independently introduced into a photosynthetically incompetent R. capsulatus mutant host strain, deficient in all known pigment-binding peptide genes. The R. sphaeroides puf operon, which encodes the L and M subunits of the reaction center as well as both peptide subunits of light harvesting complex I, was shown to be capable of complementing the mutant R. capsulatus host. Hybrid reaction centers, comprised of R. sphaeroides-encoded L and M subunits and an R. capsulatus-encoded H subunit, were formed in addition to the R. sphaeroides-encoded LHI complexes. These hybrid cells were capable of photosynthetic growth, but their slower growth rates under low light conditions and their higher fluorescence emission levels relative to cells containing native complexes, indicated an impairment in energy transduction. The Rps. viridis puf operon was found to be incapable of functional expression in the R. capsulatus mutant host. Introduction of a plasmid-borne copy of the Rps. viridis puhA gene, which encodes the H subunit of the reaction center, into host cells already containing the Rps. viridis puf operon, such that all structural peptides of the Rps. viridis reaction center were present, still did not permit stable assembly of Rps. viridis photosynthetic complexes. RNA blot analysis demonstrated that the barrier to functional expression was not at the level of transcription. Differences between Rps. viridis and R. sphaeroides that may account for their differing abilities to complement the R. capsulatus mutant host strain are discussed.Science, Faculty of
Microbiology and Immunology, Department of
Graduate
10
Gallagher, Victoria Nicole. "Photosynthetic hydrogen production by Chlamydomonas reinhardtii". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 72 p, 2007. http://proquest.umi.com/pqdweb?did=1338926921&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Texto completo da fonte
11
Liou, Je-Wen. "Scanning probe microscopy of photosynthetic membranes". Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398112.
Texto completo da fonte
12
Beoku-Betts, D. F. "Electron transfer reactions of photosynthetic proteins". Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353440.
Texto completo da fonte
13
Langley, Thomas Austin. "The isolation of non-photosynthetic plastids". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363137.
Texto completo da fonte
14
Das, Rupa 1980. "Photovoltaic devices using photosynthetic protein complexes". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/30101.
Texto completo da fonteResumo:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (leaves 59-63).
Photosynthetic proteins have been used as an active material in design of organic solar cells. Traditional organic solar cells have the limitation of not being able to absorb light in the visible-NIR region of the solar spectrum. This region corresponds to over 70% power of the total solar radiation. Using molecular proteins obtained from nature these limitations can be overcome. Biological photosynthetic complexes contain reaction centers with a quantum yield of >95% and a bandgap of less than l.leV allowing absorption in the 600-11 00nm visible-NIR range. Two types of photosynthetic complexes are employed to demonstrate the generality of the solid state integration technique to make solar cells. The simplest photosynthetic complex used is a bacterial reaction center (RC), isolated from the purple bacterium R. sphaeroides. The other protein being used is Photosystem I (PSI), a much larger complex, which is isolated from spinach chloroplasts. Electronic integration of devices is achieved by depositing organic semiconducting protective layer over a self-assembled monolayer of photosynthetic reaction centers oriented via an engineered metal-affinity polyhistidine tag. Various analytical and spectroscopic techniques have been used to examine solution spectrum and solid state device characteristics. Reasonable efficiencies have been obtained which demonstrates applicability of such techniques. The efficiency obtained is higher than a wet cell made using same proteins. The next immediate goal is to optimize processing conditions and therefore improve efficiency to reach levels comparable traditional organic solar cells.
by Rupa Das.
S.M.
15
Maeda, Hiroshi. "Vitamin E functions in photosynthetic organisms". Diss., Connect to online resource - MSU authorized users, 2006.
Encontre o texto completo da fonte
16
Lee, Sengyong. "Analyses of mutants in the 33 kDa manganese stabilizing protein of photosystem II and construction of a deletion mutant in synechococcus PCC 7942". Virtual Press, 1993. http://liblink.bsu.edu/uhtbin/catkey/865930.
Texto completo da fonteResumo:
The 33 kDa manganese stabilizing protein (MSP) has been proposed to provide ligands to stabilize Mn ions in the water lysis reaction of photosystem II of photosynthesis. In previous research site-directed mutagenesis had been performed on regions of the psbO gene encoding two aspartic acid residues of MSP which were thought to have the potential to form carboxyl bridges with Mn ions. The purpose of this research was to analyze these mutants. Plasmids pUC120-33 (#1,3,5,7,9,11,15) containing mutant psbO genes could not be isolated from E.coli because the expressed MSP was toxic to the cells. However, a psbO mutant gene carried in pPGV5-33 (#7) was isolated from E.coli and transformed into cyanobacterium Svnechococcus PCC 7942. Cyanobacterial cells carrying the MSP mutant showed a susceptibility to intensive light (100 footcandles) with a decrease of 30% in the growth rate within the first 100 hours after inoculation. This result suggested a possible function of the MSP in protecting the oxygen evolving complex from intensive light exposure. However, the mutant appeared to revert after this time probably due to homologous gene recombination with the wild type gene. In order to further analyze the function of mutants without recombination occurring, the construction of an MSP deletion was attempted using insertion of a kanamycin cartridge into the middle of the psbO gene. The inactivated psbO gene was transformed into E.coli and transformants were selected by kanamycin resistance. However, plasmid DNA carrying the interrupted genes could not be isolated, probably due to toxicity of the expression product in E.coli cells. Thus, future studies should be directed to reconstruction of a deletion mutant by direct transformation into cyanobacterial cells. Once a deletion mutant has been constructed analyses of the site-directed mutations could be performed in cyanobacteria.Department of Biology
17
Bonavia-Fisher, Bruna. "Evidence that a chloroplast membrane protein is located in the mitochondria of photosynthetic and non-photosynthetic euglenoids". Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36755.
Texto completo da fonteResumo:
1. Distribution of the two photosystems (PS I and PS II) in the thylakoid membranes of the alga Euglena gracilis. The distribution of photosystem I and II (PS I and PS II) in the alga Euglena gracilis Z strain was studied by electron microscopic immunocytochemistry. In this alga, the thylakoids are not organized in gram structures, as they are in higher plants. Two different antibodies were used to identify PS I. One is directed against particles of PS I from maize and the other against the 60 and 62 kDa PS I reaction centre proteins of the cyanobacterium Synechococcus elongatus. Both antibodies demonstrated the presence of PS I in the two types of thylakoid membranes, appressed (AM) and non-appressed (NAM). Quantitative analysis showed that 60--74% of PS I is in the AM and 26--40% is in the NAM, and since about 80--90% of the membranes are AM, that PS I is more concentrated in the NAM. An antibody directed against the CP47 protein of PS II also revealed labelling in both types of thylakoid membranes (54% in AM and 46% in NAM). PS II is again more concentrated in the NAM. I demonstrated by the photo-oxidation of 3,3'-diaminobenzidine that there is PS I activity in the two types of membranes and, moreover, that there are changes in this activity during the light cycle of the cell. My results indicate that the distribution of PS I and PS II in Euglena gracilis Z strain is different from that of higher plants and is similar to that seen in green algae. The possible evolutionary significance of our observations are discussed.2. Localization of the protein CP47 (plastid protein) in the mitochondria of euglenoids. The localization of the CP47 protein to the mitochondria of euglenoids was studied by electron microscopic immunocytochemistry. My results demonstrate that this protein, which is coded by chloroplast DNA in all algae and plants, is present in whole or in part in the mitochondria of Euglena gracilis and related euglenoids. I used two different antibodies against the protein CP47 (anti-CP47 from Chlamydomonas reinhardtii and S. elongatus) to test wild-type, light-grown, cells of Euglena. Both antibodies selectively labelled the mitochondria. These results furthermore suggest that this labelling is particularly associated with mitochondrial cristae. Anti-CP47 from S. elongatus also labelled the mitochondria of other euglenoids, such as dark-grown cells of Euglena gracilis, the mutant Y9Z1NaL, and Astasia longa. Since the CP47 protein is present in dark-grown cells and in the mutant Y9Z1NaL, which are organisms that do not have an active psbB gene, I suggest that a gene transfer has occurred from the plastid to the mitochondria during evolution. Because our results show the presence of CP47 in the mitochondria of Astasia longa, I postulate that the transfer occurred before the branching of Astasia from Euglena.
18
Tzalis, Dimitrios. "A characterization of psbO mutant genes encoding the 33 kDa protein in a cyanobacterium". Virtual Press, 1992. http://liblink.bsu.edu/uhtbin/catkey/845939.
Texto completo da fonteResumo:
This research was an attempt to characterize previously constructed mutants with a specifically altered psbO gene which encodes a 33 kDa protein active in photosynthesis. This polypeptide was believed to function in stabilization of manganese ions during photolysis of water at the photosystem II. The initial phase of this work was concerned with determining the manganese content of the genetically manipulated PS II particles of the photosynthetically active cyanobacteria.We found however, that the results of the isolation procedure for PS II particles of photosynthetically active cyanobacteria as described by Burnap et al. was not reproducible in our research organism. This prevented the chemical characterization of function of these particles as had been planned.In the second phase of the research sequencing of the mutated gene was to be performed for several clones in order to determine the kinds of specific alterations that had been made. The mutated genes had been cloned into both pUC1 20 and pPGV5 vectors which were transformed into Escherichia OR (EQQJi) and the cyanobacterium Synechococcus PCC 7942, respectively.Several attempts were mad o isolate plasmid DNA from both the transformed E QQJI and cyanobacterium. Isolation of pUC120 DNA was not achieved due to the toxicity of the 33 kDa protein product of the psbO gene in sgJj. The pPGV5 plasmid isolation was successful and PCR-sequencing was performed. However, the sequencing did not result in a readable sequence. Instead, banding patterns showed more than one nucleotide per lane. Since pPGV5 contains a strong constitutive promoter, a large amount of mutant protein was being produced. Our findings suggested that transformed cyanobacteria may have been under pressure to revert the altered gene to wild-type. Thus, upon growth of a single colony to a larger volume, a heterogeneous population of cells with different sizes of plasmids may have resulted. Restriction analysis of isolated plasmid DNA confirmed the presence of multiple-sized plasmid molecules. Therefore, this research has shown that the previously constructed mutants are not stable enough to characterize for alterations in manganese binding.Department of Biology
19
Hendry, Garth S. "Dependence of substrate-water binding on protein and inorganic cofactors of photosystem II /". View thesis entry in Australian Digital Theses Program, 2002. http://thesis.anu.edu.au/public/adt-ANU20041124.140348/index.html.
Texto completo da fonte
20
Pan, Hao. "Phylogenetic analysis of photosynthesis related proteins in Chromera velia and study of its photosynthetic response to iron limitation". Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/13921.
Texto completo da fonteResumo:
Chromera velia (C.velia) is a newly discovered algal species in Australia (Moore et al., 2008). It possesses photosynthetic characteristics similar to photosynthetic dinoflagellates, but has physiological and molecular features of non-photosynthetic apicomplexan parasites. Hence, it has been proposed that C.velia may be the missing link between photo-autotrophic dinoflatellates and heterotrophic apicomplexans. This project aimed to: (1.) analyse the light harvesting complexes (LHC) and enzymes involved in the Calvin-Benson cycle in C.velia using a phylogenetic method to obtain a better understanding of the evolutionary development of light and dark reactions in photosynthesis; and (2.) characterize the photosynthetic apparautus in C.velia under normal and iron-stress conditions using a set of biochemical analysis methods as well as bioinformatics. LHC comprise proteins that absorb light energy and transfer it to photosynthetic reaction centres. Sequencing of the LHC in C.velia identified three typical membrane spanning regions (MSR). Phylogenetic analysis indicates that one group is closely related to diatoms, another to red algae, and a third one containing a LHC peptide closely related to the LI818/LHCSR group in charge of photosynthesis regulation. This is the first time LHC in C.velia have been analysed using phylogenetic methods. Our results clearly support the hypothesis that there is a connection between C.velia and diatoms (Moore et al., 2008). This relationship was also confirmed by protein sequencing of isolated LHC from C.velia. The Calvin-Benson cycle is an important part of the dark reaction of photosynthesis. It fixes CO2 and converts inorganic carbon into organic chemicals using adenosine triphosphate synthesized from light reactions. Phylogenetic analysis of the enzymes involved in the Calvin-Benson cycle in C.velia revealed a complicated evolutionary pathway. The majority of enzymes in C.velia originate from proteobacteria, with two exceptions (Fructose-bisphosphate aldolase and Phosphoribulokinase). Different enzymes in C.velia share close relationships with green algae, red algae, diatoms, photosynthetic dinoflagellates, and Apicomplexa. We carried out our phylognetic analysis of the enzymes involved in the Calvin-Benson cycle as a whole for the first time. Our results clearly showed that these enzymes have a mosaic pattern of evolutionary relationships with other groups, supporting the “shopping bag” theory proposed by Larkum et al. (2007). Iron is an essential element for photosynthesis, vital for assembling photosystem I and other photosynthetic proteins. Given that the oxidized form of iron does not dissolve in water, iron is often limited in the marine environment. Therefore, oxygenic photosynthetic organisms have developed different strategies to cope with iron limitation during their evolutionary process. A study of iron-stress response in the primitive C.velia can help improve our understanding of its photosynthetic system. Our study revealed that iron-stress conditions led to decreased growth rate (with a doubling time of 7.54 days in the iron-stress culture, compared with 2.82 days in a normal culture), decreased oxygen evolution rate, decreased chlorophyll concentration per cell, shifted carotenoid composition, and shifted protein expression pattern. As a potential evolutionary intermediate between photoautotrophs and heterotrophs, C.velia offers an excellent opportunity to explore the link the evolutionary development of photosynthesis in apicomplexan parasites. Thus, phylogenetic analysis and study of its photosynthetic apparatus contributes to a better understanding of its evolutionary development as well as its inherent molecular mechanism.
21
Masot, Mata Alexandra. "Engineering photosynthetic systems for bioregenerative life support". Doctoral thesis, Universitat Autònoma de Barcelona, 2007. http://hdl.handle.net/10803/5312.
Texto completo da fonteResumo:
El projecte MELiSSA (Micro-Ecological Life Support System Alternative) de l'Agència Espacial Europea (ESA) és un ecosistema artificial concebut com una eina per estudiar i desenvolupar la tecnologia per a sistemes de suport de vida biològics requerits per a missions tripulades de llarga durada a l'espai. El fet que el projecte internacional MELiSSA es desenvolupa en cooperació amb organitzacions de diferents països ha permès que el treball experimental d'aquesta tesi es realitzés part a la Planta Pilot MELiSSA (MPP), ubicada a la Universitat Autònoma de Barcelona (Spain), i part a Controlled Environmental Systems Research Facility de la University of Guelph (Canada). Inspirant-se en un ecosistema natural aquàtic, el bucle MELiSSA produeix aliments, aigua i oxigen a partir de la degradació dels residus orgànics (biomassa no comestible, femta, orina i CO2) utilitzant l'activitat combinada de diferents microorganismes i plantes superiors, que colonitzen cinc compartiments interconectats. L'objectiu d'aquesta tesi és avançar en el desenvolupament dels compartiments fotosintètics del bucle per tal de ser integrats a la MPP. Concretament, el treball s'ha estructurat en 3 unitats principals.
I - Compartiment d'Arthrospira:
S'han realitzat cultius en continu a diferents velocitats de dilució i intensitats lumíniques (seleccionades segons un disseny central composat tipus Box Wilson) per determinar els límits operacionals i la màxima productivitat del fotobioreactor a escala pilot d'Arthrospira. La productivitat més alta aconseguida fou de 27 mg·L-1·h-1 a una velocitat de dilució de 0.044 h-1 i 194 W·m-2. S'ha estudiat la resposta dels cultius davant de pertorbacions afectant el pH i els cabals de líquid i gas. De forma més detallada, s'ha avaluat l'efecte de l'amoni en la producció i composició de l'Arthrospira, determinant que per tal d'evitar l'inhibició del creixement d'Arthrospira cal mantenir les concentracions d'amoni a l'estat estacionari per sota de 5.6 mM.
II - Compartiment de Plantes Superiors:
S'han realitzat cultius de remolatxa i enciam dins de cambres de plantes estanques per obtenir dades de referència de productivitat, composició, consum de nutrients i fixació de carboni. La productivitat mitjana entre els 3 cultius en discontinu i els 2 en etapes és de 15.31 g dw·m-2·d-1 per remolatxa i de 13.85 g dw·m-2·d-1 per enciam. La mesura de la fixació neta de carboni és una bona tècnica per estimar el creixement i la producció de les plantes dintre les cambres sense utilitzar mètodes destructius. A més, s'ha provat que el consum de nutrients permet estimar el contingut mineral total dins la cambra utilitzant la producció de biomassa. També s'ha avaluat l'adequació d'un model fotosintètic per estimar la producció de biomassa dins la cambra. S'ha conclòs que el model hiperbòlic és adequat per descriure la resposta fotosintètica d'una fulla a diferents intensitats lumíniques. A més l'estimació dels corresponents paràmetres ha permès determinar que ni el rendiment quàntic (?), ni la velocitat fotosintètica màxima (Pmax) ni la velocitat de respiració (Rd) depenen de l'edat de la planta i únicament la Pmax depèn de la concentració de CO2.
III - Integració dels Compartiments Fotosintètics:
S'han dimensionat i dissenyat les cambres de plantes que s'integraran pròximament a la MPP. Les 3 cambres de plantes amb una àrea de producció de 5 m2 cada una tindran una producció de biomassa comestible (remolatxa, enciam i blat) equivalent al 20% dels requeriments diaris d'un humà. La configuració seleccionada (una cambra allargada amb dues subcàmares estanques a cada banda) permetrà obtenir una producció semicontínua de biomassa i assegurar d'estanqueïtat del sistema. Finalment, s'ha avaluat l'impacte de la integració dels compartiments fotosintètics a la MPP desenvolupant un model que permet calcular els balanços de nitrogen, CO2 i O2 dins del bucle i determinar en quines condicions és possible aconseguir el tancament dels mateixos.
The MELiSSA project (Micro-Ecological Life Support System Alternative) of the European Space Agency is an artificial ecosystem conceived as a tool to study and develop technology for a future biological life support system required for long term manned space missions. The fact that the MELiSSA project is formed by several independent organizations of different countries made possible that part of the experimental work of this thesis was carried out in the MELiSSA Pilot Plant (MPP) located at Universitat Autònoma de Barcelona (Spain) and the Controlled Environmental Systems Research Facility located at University of Guelph (Canada).
Based on the principle of an aquatic ecosystem, MELiSSA aims to produce food, fresh water and oxygen from organic wastes (inedible biomass, faeces, urine and CO2) using the combined activity of several microorganisms and higher plants, which colonize five interconnected compartments. The main contribution of this thesis is in the engineering of the photosynthetic compartments and their integration into MPP. Particularly, the work has been structured in the following three main units.
I - Arthrospira Compartment:
Several continuous cultures have been carried out at different dilution rates and light intensities, planned using a Box-Wilson Central Composite Design, to determine the operational limits and maximum productivity of Arthrospira pilot plant photobioreactor. The highest Arthrospira productivity attained is 27 mg·L-1·h-1 at a dilution rate of 0.044 h-1 and a light intensity of 194 W·m-2. Disturbances of normal operating conditions affecting pH, liquid and gas flow rate influence Arthrospira growth has been studied. The effect of ammonium on Arthrospira production and composition has been evaluated in detail and it is determined that to avoid inhibition of the Arthrospira growth, the steady-state ammonium concentration must be lower than 5.6 mM.
II - Higher Plant Compartment:
Three batch and two staggered cultures in sealed environment chambers have been performed to collect baseline data of productivity, tissue composition, nutrient uptake and canopy photosynthesis from beet and lettuce trials. The mean total plant productivity among batch and staggered cultures is 15.31 g dw·m-2·d-1 for beet and 13.85 g dw·m-2·d-1 for lettuce. The net carbon exchange rate technique is a good alternative to classical growth analysis for estimating plant growth and production inside the chamber without using destructive analyses. In addition to this, the ionic uptake of the nutrient solution has been proven to be a good predictor of total canopy mineral content using the estimated biomass. Moreover, the photosynthetic study performed at leaf level has contributed to estimates of light energy related parameters for the canopy model. The rectangular hyperbola model is suitable in defining the leaf photosynthetic response to light at different CO2 levels and crop ages. No significant differences are detected for the quantum yield (?) and dark respiration rate (Rd) among CO2 levels, but in contrast, the maximum photosynthetic rate (Pmax) was found to depend on CO2 concentration. Moreover, it is observed that that ?, Pmax and Rd values remain constant through crop development.
III - Photosynthetic Compartments Integration:
The HPC prototype to be integrated into the MPP has been designed. It is concluded that 3 HPC prototypes with 5 m2 of growing area each, will be constructed to provide 20% of the daily crew diet with beet, lettuce and wheat. The selected configuration, an elongated chamber with two air-locks at each end, allows the semi-continuous biomass production while ensuring gas environment isolation. Finally, the impact of the integration of the photosynthetic compartments into the MPP has been evaluated using a static mass balance model for assessing the nitrogen, CO2 and O2 balances, while determining the conditions under which the closure of the mass balances can be expected.
22
Hill, Ross. "Coral bleaching : photosynthetic impacts on symbiotic dinoflagellates /". Electronic version, 2008. http://hdl.handle.net/2100/526.
Texto completo da fonteResumo:
University of Technology, Sydney. Faculty of Science.Global climate change is leading to the rise of ocean temperatures and is triggering mass coral bleaching events on reefs around the world. This involves the expulsion of the symbiotic dinoflagellate algae, known as zooxanthellae, from the coral host. Coral bleaching is believed to occur as a result of damage to the photosynthetic apparatus of these symbionts, although the specific site of initial impact is yet to be conclusively resolved. This thesis examined a number of sites within the light reactions of photosynthesis and evaluated the efficiency of photoprotective heat dissipating pathways. Upon expulsion, the capacity for long-term survivorship of expelled zooxanthellae in the water column was also assessed. A reduction in photosystem II (PSII) photochemical efficiency during exposure to elevated temperature and high light (bleaching conditions) was found to be highly dependent upon the increase in abundance of QB non-reducing PSII centres (inactive PSII centres), indicating damage to the site of the secondary electron acceptor, QB, resulting in a limited capacity for its reduction. Therefore, this reduced the rate of the reoxidation of the primary electron acceptor, QA-. Fast induction curve (FIC) analysis of the rise from minimum fluorescence to maximum fluorescence revealed a lower amplitude in the J step along this curve, which was consistent with a reduction in the rate of QA reoxidation. This photoinhibition of PSII was found to occur once the effectiveness of excess energy dissipation through energy-dependent quenching and state-transition quenching was exceeded, suggesting that these mechanisms were incapable of preventing photodamage. Antenna size heterogeneity showed little change under bleaching conditions with a significant increase in PSIIbeta only apparent in one species of coral. The thermostability of the oxygen evolving complex (OEC) and thylakoid membrane were found to increase during exposure to bleaching conditions and exceeded bleaching thresholds of corals. This rapid rise in temperature-dependent thermostability also occurred over seasons, where variation in ocean temperatures was matched by gradual shifts in OEC and thylakoid membrane thermotolerance. Variation in thermostability between species was not found to be linked to zooxanthellae genotype, and instead was related to the bleaching susceptibility of the host. Despite this capacity for resilience to bleaching conditions, the PSII reaction centres did not exhibit such a mechanism for rapid acclimatisation. Corals can only be as tolerant to bleaching conditions as their most sensitive component allows. The formation of nonfunctional PSII centres is therefore suggested to be involved in the initial photochemical damage to zooxanthellae which leads to a bleaching response. Zooxanthellae were found to be expelled irrespective of OEC function and thylakoid membrane integrity, as these sites of the photosynthetic apparatus were still intact when cells were collected from the water column. Although zooxanthellae were photosynthetically competent and morphologically intact upon expulsion, their longevity in the water column was dependent on the time of expulsion following the onset of bleaching and the ambient water temperatures. The survivorship of these zooxanthellae was restricted to a maximum of 5 days in the water column which suggests that unless expelled zooxanthellae inhabit other environs of coral reefs which may be more favourable for survival, their capacity for persistence in the environment is extremely limited. Chlorophyll a fluorescence measurements are a common tool for investigating photosynthetic impacts to in hospite zooxanthellae of corals. Pathways causing dark-reduction of the plastoquinone pool are shown to be active in corals and affect measurements which require dark-adaptation. Pre-exposure to far-red light was found to be an effective procedure to oxidise the inter-system electron transport chain and ensure determination of the true maximum quantum yield of PSII and accurate FICs. It is concluded that the trigger for coral bleaching lies in the photosynthetic apparatus of zooxanthellae and evidence is presented in support of this impact site not being the OEC or thylakoid membrane.
23
Zhang, Haoyu. "Studies of zeolite-based artificial photosynthetic systems". Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1203019490.
Texto completo da fonte
24
Goncalves, da Cruz Sonia Marisa. "Photosynthetic energy dissipation and chlororespiration in diatoms". Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522439.
Texto completo da fonte
25
Torabi, Salar Abu-Torab. "Establishment of photosynthetic complexes in the chloroplast". Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-183292.
Texto completo da fonte
26
Sayed, O. H. "Photosynthetic responses to high temperature in wheat". Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234213.
Texto completo da fonte
27
Nichol, Caroline Jane. "Remote sensing of photosynthetic-light-use efficiency". Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/15517.
Texto completo da fonteResumo:
Narrow waveband spectral reflectance, chlorophyll fluorescence and gas exchange measurements were made sequentially on individual leaves of Vicia faba at three levels of 500, 1000 and 1500 mmol m-2 s-1. PRI was calculated from the reflectance data and correlated with LUE calculated from gas exchange and photosystem II( PS II) efficiency measured from chlorophyll fluorescence. PRI was linearly related to photosystematic LUE and PS II efficiency over the range of light levels and followed the diurnal light response of photosynthetic light-use-efficiency. The relationship between PRI and LUE was then investigated over boreal forests in Canada. Reflectance measurements of four stands were made from a helicopter-mounted spectroradiometer during the 1994 growing season. Eddy covariance towers were measuring CO2 fluxes during this time and LUE was calculated from these data. A strong linear relationship was found between PRI and LUE for the four sites, and when expressed on a functional type basis of conifer and deciduous, the relationships were stronger still. The relationship between PRI and LUE at the canopy scale was further investigated in boreal forest in Siberia during the "green-up" period from winter into spring in 2000. During this time the photosystems were under stress as a result of extremes of temperature (from -20°C to +35°C) coupled with a high radiation load. Reflectance measurements of four stands were made from a helicopter-mounted spectroradiometer and PRI was calculated from these data. Eddy covariance towers were operating at each site and offered a means to calculate LUE. A significant linear relationship was apparent between PRI and LUE although the relationship was weaker than that found between PRI and LUE in the Canadian boreal forest. Collating the data for all the boreal forests highlighted a difference between the slopes of the PRI:LUE relationship. Reflectance measurements were also made from the eddy covariance tower of the Scots pine canopy and needles were sampled simultaneously for xanthophyll pigment determination. Strong linear relationships were observed between PRI, the epoxidation state of the xanthophyll cycle and LUE over the seasonal change and the diurnal cycle.
28
Johansson, Staffan Andreas. "Improving photosynthetic conversion efficiency in marine microalgae". Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/400390/.
Texto completo da fonteResumo:
Marine photosynthetic microalgae have great potential in biotechnology. They have huge genetic diversity and naturally make an array of metabolites that are precursors in high value products such as fuels and pharmaceuticals. They do not compete with agriculture for land or fresh water and can be used to reduce industrial carbon-emissions. In order to realize this potential however much work needs to be done to overcome the engineering challenges of growing microalgae on large scales and developing the genetic tools required to increase the yield and diversity of products synthesized by cells. Irrespective of the type of microalgal species selected for growth, the efficiency at which light energy is converted into product, the 'photosynthetic conversion efficiency' sets a fundamental limitation on the potential yield. In natural systems as much as 90% of absorbed light energy is re-emitted as heat or fluorescence, representing a major loss in overall efficiency. In this thesis a high-throughput pipeline using random mutagenesis and live single cell sorting has been used to isolate two cell-lines of the eukaryotic microalgae Dunaliella tertiolecta with reduced chlorophyll content (termed lca1 and lca2). As there is no published genome for D. tertiolecta and the species is difficult to transform, this approach represents a feasible method to develop improved cell-lines from any microalgal species. These cell lines are characterized physiologically and shown to increase the maximum rate of chlorophyll-normalized photosynthesis Pmax by 289 (lca1) and 131% (lca2) respectively. The molecular basis of these random mutations characterized by transcriptomics using next-generation sequencing approaches, helps define the differences in regulation in light-harvesting and photosynthesis between the lca1, lca2 and wild-type. The approaches applied in this thesis therefore show how microalgal strains with poor genetic characterization can rapidly be selected for biotechnological applications, and providing new gene targets and valuable insights into the fundamental mechanisms of photosynthesis.
29
Falcone, Deane Louis. "Regulation of CO₂ fixation in photosynthetic bacteria /". The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487779914825823.
Texto completo da fonte
30
Moustafa, Ahmed Bhattacharya Debashish. "Evolutionary and functional genomics of photosynthetic eukaryotes". Iowa City : University of Iowa, 2009. http://ir.uiowa.edu/etd/311.
Texto completo da fonte
31
Mothersole, David J. "Assembly, structure and organisation of photosynthetic membranes". Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4824/.
Texto completo da fonte
32
Langford, Penny. "The photosynthetic ability of Rosa in vitro". Thesis, University of Bath, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377366.
Texto completo da fonte
33
Moustafa, Ahmed. "Evolutionary and functional genomics of photosynthetic eukaryotes". Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/311.
Texto completo da fonteResumo:
My dissertation focuses on genome and functional evolution of photosynthetic eukaryotes and the design and implementation of computational methods and tools to enable genome-wide studies to investigate these taxa. The work described here is grouped into two major topics, 1) endosymbiosis and genome evolution, and 2) harmful algal blooms. I discuss my work related to endosymbiosis and genome evolution in chapters 2-4. Chapters 5-6 cover the work related to harmful algal blooms. In chapter 1, I introduce the state-of-art of what is known about the history of plastids and evolution of photosynthesis in eukaryotes, an overview of marine harmful algae, and the specific aims of my dissertation.
In chapter 2, I describe the design and implementation of the phylogenetic sorting tool, PhyloSort and the assembly of a high-throughput phylogenomic pipeline. Together, PhyloSort and the pipeline has become a key tool for multiple subsequent studies. chapter 2 also presents a case study using these tools in which we provide an estimate of the number of cyanobacterial genes that have been transferred to the nuclear genome of Plantae through primary endosymbiotic gene transfer; I use the model unicellular green alga Chlamydomonas reinhardtii for this purpose.
In chapter 3, I discuss another case of prokaryotic contribution to the nucleus of photosynthetic eukaryotes. Here, the intriguing relationship of Chlamydiae-like bacteria and plants and algae is examined in a large-scale analysis, in which we scanned all available genomes of the primary photosynthetic organisms for genes of potential Chlamydiae origin. Surprisingly, we identified more than fifty Chlamydiae-derived genes in plants and algae. Here, we propose a model for the role that a Chlamydiae-like symbiont might have played in the establishment of the primary plastid in the common ancestor of Plantae.
In chapter 4, I describe a study in which we explored the complete protein models of two diatom organisms as representative for photosynthetic chromalveolates and looked for genes that might have been acquired through endosymbiotic (secondary) or horizontal transfers from red or green algae. In contradiction of the “chromalveolate hypothesis” which states that photosynthesis in chromalveolates originated via the engulfment of a red alga symbiont, our study shows an unexpected green algal contribution that is fourfold greater than that of the canonical red algal symbiont. Our data suggest that the chromalveolate history includes a previously unrecognized green algal endosymbiont that was captured and lost prior to the more recent establishment of the red alga plastid, which is widespread in extant photosynthetic chromalveolates.
In chapter 5, I discuss the identification of the phylogenetic origin of the genes involved in the biosynthetic pathway of saxitoxin in cyanobacteria. Here, we used a pyrosequencing approach to sequence de novo genomes of two strains of Anabaena circinalis, one of which is saxitoxin-producing and the other is non-toxic. Using comparative and phylogenetic analyses, I show that, within the saxitoxin gene cluster, genes that encode the key and unique enzymes in the pathway are of foreign origin that originated via horizontal transfer from non-cyanobacterial sources. These genes introduced the ability to produce saxitoxin in the ancestor of the toxic cyanobacterial clade.
In chapter 6, I describe a gene expression study in which we used massively parallel signature sequencing (MPSS) to investigate RNA abundance patterns in the toxic dinoflagellate Alexandrium tamarense. This work provides the first clear evidence for the utilization by dinoflagellates of transcriptional to regulation. Moreover, using MPSS, we provide an estimate of the number of the distinct genes in Alexandrium tamarense; i.e., remarkably 40,000 loci. Taken together, our data indicate that dinoflagellates possess a great metabolic flexibility that allows them to efficiently toggle between photoautotrophy and heterotrophy based on the environmental conditions.
34
Ponce, Toledo Rafael Isaac. "Origins and early evolution of photosynthetic eukaryotes". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS047/document.
Texto completo da fonteResumo:
Les plastes primaires proviennent d'une cyanobactérie qui a établi une relationendosymbiotique avec un hôte eucaryote. Cet événement a donné naissance au super-groupeArchaeplastida qui inclut les Viridiplantae (algues vertes et plantes terrestres), les Rhodophyta (alguesrouges) et les Glaucophyta. Suite à l'endosymbiose primaire, les algues rouges et vertes ont étendu lacapacité de photosynthèse à d'autres lignées eucaryotes via des endosymbioses secondaires. Bien quedes progrès considérables aient été réalisés dans la compréhension de l'évolution des eucaryotesphotosynthétiques, d'importantes questions sont restées ouvertes, telles que l’identité de la lignéecyanobactérienne la plus proche des plastes primaires ainsi que le nombre et l'identité des partenairesdans les endosymbioses secondaires.Ma thèse a consisté à étudier l'origine et l'évolution précoce des eucaryotes photosynthétiques enutilisant des approches phylogénétiques et phylogénomiques. Je montre par mon travail que les plastesprimaires ont évolué à partir d'un symbiote phylogénétiquement proche de Gloeomargarita lithophora,une cyanobactérie représentant un clade s’étant diversifié précocement et qui a été détectéeuniquement dans les milieux terrestres. Ce résultat fournit des pistes nouvelles sur le contexteécologique dans lequel l'endosymbiose primaire a probablement eu lieu. En ce qui concerne l'évolutiondes lignées eucaryotes avec des plastes secondaires, je montre que les génomes nucléaires deschlorarachniophytes et des euglénophytes, deux lignées photosynthétiques avec des plastes dérivésd'algues vertes, encodent un grand nombre de gènes acquis par transferts depuis des algues rouges.Enfin, je mets en évidence que SELMA, la machinerie de translocation des protéines à travers laseconde membrane externe des plastes rouges secondaires à quatre membranes, a une histoireétonnamment compliquée aux implications évolutives importantes : les cryptophytes ont recruté unensemble de composants de SELMA différent de ceux des haptophytes, straménopiles et alvéolés.Ainsi, ma thèse a permis d’identifier pour la première fois la lignée cyanobactérienne la plus proche desplastes primaires et apporte de nouvelles pistes pour éclaircir les événements complexes qui ontjalonné l’évolution des eucaryotes photosynthétiques secondairesPrimary plastids derive from a cyanobacterium that entered into an endosymbioticrelationship with a eukaryotic host. This event gave rise to the supergroup Archaeplastida whichcomprises Viridiplantae (green algae and land plants), Rhodophyta (red algae) and Glaucophyta. Afterprimary endosymbiosis, red and green algae spread the ability to photosynthesize to other eukaryoticlineages via secondary endosymbioses. Although considerable progress has been made in theunderstanding of the evolution of photosynthetic eukaryotes, important questions remained debatedsuch as the present-day closest cyanobacterial lineage to primary plastids as well as the number andidentity of partners in secondary endosymbioses.The main objectives of my PhD were to study the origin and evolution of plastid-bearing eukaryotesusing phylogenetic and phylogenomic approaches to shed some light on how primary and secondaryendosymbioses occurred. In this work, I show that primary plastids evolved from a close relative ofGloeomargarita lithophora, a recently sequenced early-branching cyanobacterium that has been onlydetected in terrestrial environments. This result provide interesting hints on the ecological setting whereprimary endosymbiosis likely took place. Regarding the evolution of eukaryotic lineages with secondaryplastids, I show that the nuclear genomes of chlorarachniophytes and euglenids, two photosyntheticlineages with green alga-derived plastids, encode for a large number of genes acquired by transfersfrom red algae. Finally, I highlight that SELMA, the translocation machinery putatively used to importproteins across the second outermost membrane of secondary red plastids with four membranes, has asurprisingly complex history with strong evolutionary implications: cryptophytes have recruited a set ofSELMA components different from those present in haptophytes, stramenopiles and alveolates.In conclusion, during my PhD I identified for the first time the closest living cyanobacterium to primaryplastids and provided new insights on the complex evolution that have undergone secondary plastid-bearing eukaryotes
35
Jensen, Brandi Jean. "The role of infrared radiation in the evolution and ecology of anaerobic photosynthetic bacteria". Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594477811&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Texto completo da fonte
36
Evertsen, Jussi. "Solar powered phycozoans : Herbivore sacoglossans with photosynthetic chloroplasts". Doctoral thesis, Norwegian University of Science and Technology, Department of Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2244.
Texto completo da fonte
37
Hardjasa, Amelia. "Structures of photosynthetic reaction centers with alternative cofactors". Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54057.
Texto completo da fonteResumo:
Rhodobacter sphaeroides is a model organism for the study of bacterial photosynthesis. The R. sphaeroides photosynthetic reaction centre (RC) is the primary site of electron transfer, which is mediated by the photosynthetic pigments bacteriochlorophyll a (BChl) and bacteriopheophytin (BPhe). The substitution of key amino acid residues can change the type of cofactors present in the RC. In particular, studies have shown that when the leucine residue in position 214 of the M subunit [(M)L214] is converted into a histidine, the BPhe normally present in the neighbouring position (HA) is replaced with a BChl. This study investigated the hypothesis that steric exclusion by the coordinating residue causes dechelation of the central magnesium ion in BChl, producing BPhe. Crystal structures of RCs where (M)L214 is substituted for glycine and alanine were determined, which demonstrated that the presence of BPhe in the HA pocket is unchanged despite decreasing the size of the residue in position (M)214. A crystal structure of an RC where (M)L214 is substituted for asparagine was also determined and showed that the replacement of BPhe with BChl at HA occurs if residue (M)214 includes an amide moiety. In the R. sphaeroides Δbchd strain, which lacks the ability to make BChl, it is believed that the RC cofactor sites are populated exclusively with zinc-bacteriochlorophyll (Zn-BChl). The crystal structures of this Zn-BChl containing RC (Zn-RC) and a Zn-RC with the (M)L214H substitution (Zn-β-RC) were solved for the first time. These structures confirmed the presence of Zn-BChl in every cofactor position and the tetracoordination of the HA Zn-BChl in the Zn-β-RC, as well as revealing that the occupancy of the HB cofactor was much lower than that of all other cofactors.Science, Faculty of
Microbiology and Immunology, Department of
Graduate
38
Smith, Monica Elizabeth. "Photosynthetic performance of single-cell C₄ species (Chenopodiaceae)". Online access for everyone, 2007. http://www.dissertations.wsu.edu/Thesis/Fall2007/m_smith_111907.pdf.
Texto completo da fonte
39
Pearman, John K. "Molecular ecology and transcriptomics of marine photosynthetic picoeukaryotes". Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/45785/.
Texto completo da fonteResumo:
Photosynthetic picoeukaroytes (PPEs), defined here as single celled organisms <3 μm in diameter, are significant contributors to primary production. Until recently, marine PPEs had received relatively little research attention in contrast to the more numerous picocyanobacteria. Molecular studies have now started to reveal the diversity of this group, using both the nuclear 18S rRNA gene and the plastidtargeted 16S rRNA gene as taxonomic markers. The latter marker has the advantage of directly targeting the PPE community, counteracting the problem of heterotrophic sequences dominating clone libraries. As well as PCR based molecular approaches, genomic studies of PPEs are starting to reveal the metabolic capabilities of these organisms. In this thesis, taxonomic information obtained on two flow-sorted PPE populations (Euk-A and Euk-B) showed that pico-prymnesiophytes, largely representing lineages with no close cultured counterpart, dominated the Euk-A and Euk-B libraries (54 and 58%, respectively) in tropical and sub-tropical waters of the Atlantic Ocean. Radiotracer work performed elsewhere had shown these PPE groups contribute up to 19% and 38% (Euk-A and Euk-B, respectively) to total CO2 fixation, demonstrating the importance of these PPE groups in marine carbon cycling. To further assess the taxonomic composition and distribution of these Euk-A and Euk-B PPE populations at the ocean-basin scale, clone libraries were constructed along an Atlantic Meridional Transect (AMT18). Major components of these flow cytometry sorted PPE populations were Prymnesiophyceae and Chrysophyceae using plastid markers, or Prasinophyceae and Dinophyceae (nuclear markers) including several lineages with no cultured counterparts. In surface waters a latitudinal diversity gradient was observed with a peak in PPE diversity found in the equatorial region. Distribution patterns of specific PPE groups and OTUs were subsequently correlated with measured environmental parameters, although most of the variation in PPE diversity was not explained by the measured variables. Attempts were undertaken to obtain into culture novel PPEs, especially those representative of oligotropic regions. However, the majority of isolates obtained were related to Prasinoderma or Chlorella which are cosmopolitan, fast-growing genera. Even so, some isolates more relevant of open ocean environments were obtained, including a clade VIIA prasinophyte and a Pelagomonas sp. Trancriptomics was used to further assess the functional potential of specific PPE populations, firstly in cultures using both an Ochromonas sp. and a prasinophyte as being representative of organisms present along AMT18. This approach revealed a C4 carbon concentrating mechanism in the clade VIIA prasinophyte and enzymes required for a functioning urea cycle in the Ochromonas sp. A pipeline was also developed to undertake a metatranscriptomic approach on a flow cytometrically sorted PPE population from the south Atlantic gyre. This approach revealed a diatom-like C4 carbon concentrating system in the metatranscriptome. Overall, this thesis has given new insights into the diversity of specific PPE groups at the ocean basin-scale, developed a new pipeline for the transcriptomic analysis of PPEs both in culture and in the environment, and in so doing has provided new information on the functional potential of these important photosynthetic organisms.
40
Forster, Rodney Malcolm. "The control of photosynthetic capacity in aquatic plants". Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317439.
Texto completo da fonte
41
Wood, Louise. "Photosynthetic characteristics of free-living phycobionts from lichens". Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299048.
Texto completo da fonte
42
Harrison, Michael Andrew. "Molecular mechanisms of adaptation in the photosynthetic apparatus". Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277375.
Texto completo da fonte
43
Savage, Anne Margaret. "Genetic diversity and photosynthetic characteristics of zooxanthellae (Symbiodinium)". Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369298.
Texto completo da fonte
44
Whitford, D. "The role of cytochromes in photosynthetic electron transport". Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37894.
Texto completo da fonte
45
Thorne, Rebecca. "Bio-photo-voltaic cells (photosynthetic-microbial fuel cells)". Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548097.
Texto completo da fonteResumo:
Photosynthetic Microbial Fuel Cell (p-MFC) research aims to develop devices containing photosynthetic micro-organisms to produce electricity. Micro-organisms within the device photosynthesise carbohydrates under illumination, and produce reductive equivalents (excess electrons) from both carbohydrate production and the subsequent carbohydrate break down. Redox mediators are utilised to shuttle electrons between the organism and the electrode. The mediator is reduced by the micro-organism and subsequently re-oxidised at the electrode. However this technology is in its early stages and extensive research is required for p-MFC devices to become economically viable. A basic p-MFC device containing a potassium ferricyanide mediator and the algae Chlorella vulgaris was assembled and tested. From these initial experiments it was realised that much more work was required to characterise cell and redox mediator activities occurring within the device. There is very little p-MFC literature dealing with cellular interaction with redox mediators, but without this knowledge the output of complete p-MFC devices can not be fully understood. This thesis presents research into the reduction of redox mediators by the micro-organisms, including rates of mediator reduction and factors affecting the rate. Both electrochemical and non-electrochemical techniques are used and results compared. Additionally, cellular effects relating to the presence of the mediator are studied; crucial to provide limits within which p-MFCs must be used. After basic characterisation, this thesis presents work into the optimisation of the basic p-MFC. Different redox mediators, photosynthetic species and anodic materials are investigated. Importantly, it is only through fundamental characterization to improve understanding that p-MFCs can be optimised.
46
Agić, Heda. "Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes". Doctoral thesis, Uppsala universitet, Paleobiologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-265229.
Texto completo da fonteResumo:
One of the most important events in the history of life is the evolution of the complex, eukaryotic cell. The eukaryotes are complex organisms with membrane-bound intracellular structures, and they include a variety of both single-celled and multicellular organisms: plants, animals, fungi and various protists. The evolutionary origin of this group may be studied by direct evidence of past life: fossils. The oldest traces of eukaryotes have appeared by 2.4 billion years ago (Ga), and have additionally diversified in the period around 1.8 Ga. The Mesoproterozoic Era (1.6-1 Ga) is characterised by the first evidence of the appearance complex unicellular microfossils, as well as innovative morphologies, and the evolution of sexual reproduction and multicellularity. For a better understanding of the early eukaryotic evolution and diversification patterns, a part of this thesis has focused on the microfossil records from various time periods and geographic locations. Examination of microfossil morphology, cell wall microstructure and biochemical properties, reflect their intracellular complexity and function, and allow reconstructions of their life cycle, as well as observing the evolutionary pattern of change from Mesoproterozoic, to Cambrian-Ordovician transition. Several case studies included assemblages deriving from Mesoproterozoic, Neoproterozoic and early Paleozoic time intervals that show disparate morphotypes and innovative features indicative of algal clades. The Mesoproterozoic Ruyang Group in northern China has yielded a diverse microfossil assemblage that provides important clues about the diversification of different eukaryotic groups. Furthermore these microfossils contributed an additional evidence for the emergence of the crown group Eukarya by 1.7-1.4 Ga. In another part of this thesis, examination of wall microstructure and chemical properties via Raman spectroscopy has been used to assess the biological affinities of various Neoproterozoic problematic carbonaceous compression fossils. Studies on the early Phanerozoic (c. 545-485 Ma) assemblages from Estonia reconstructed patterns of the early radiations of phytoplankton and its evolutionary innovations. A continuing theme in this thesis has been using a combination of evidence of microfossils’ fine-scale morphology, ecology and chemical properties to determine their function in life, in addition to their systematic position.Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes
47
Vaughan, Felix Matthew William Chase. "Exciton energy transfer in photosynthetic light harvesting complexes". Thesis, University of Bristol, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.761220.
Texto completo da fonte
48
Stross, Clement David. "Energy transfer and initial states in photosynthetic complexes". Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.730844.
Texto completo da fonte
49
Cline, Sara G. "The Biogenesis of Photosynthetic Complexes PSII and b6f". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1339709844.
Texto completo da fonte
50
Lee, Choon-Hwan. "Multilinear analysis of fluorescence spectra of photosynthetic systems /". The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487594970651308.
Texto completo da fonte