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Cartalas, Jérémy. "Characterization of the RNA maturation-degradation machinery in plant mitochondria." Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAJ003.
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Les mitochondries sont le lieu de production de l'énergie des cellules eucaryotes. La mitochondrie possède son propre transcriptome. Ainsi pour générer un transcriptome mature et efficient, tout un ensemble de RNases permettent la maturation et la dégradation de l'ARN. Parmi elles la protéine MNU2 a été caractérisé comme ayant un rôle dans la maturation. Mais elle pourrait également jouer un rôle dans la dégradation. Au cours de mon doctorat, j'ai montré que MNU2 pourrait être un hub pour un degradosome, en interagissant avec la mtPNPase et une polyA polymérase J'ai généré des mutants mnu2, et afin de caractérisé sa fonction j'ai adapté des méthodes de Séquençages nouvelles générations et les appliquer dans des approches de génétiques inverse. Mes recherches ont montré un rôle déterminant de MNU2 dans la définition des extrémités 5' des ARNs mitochondriaux. Il a également permis de mettre en lumière une potentiel voie de dégradation 5'-3'Mitochondria are the site of energy production in eukaryotic cells. Mitochondria have their own transcriptome. In order to generate a mature and efficient transcriptome, a whole range of RNases are required for RNA maturation and degradation. Among these, the MNU2 protein has been characterized as having a role in maturation. But it could also play a role in degradation. During my PhD, I showed that MNU2 could be a hub for a degradosome, interacting with mtPNPase and a polyA polymerase. I generated mnu2 mutants, and in order to characterize its function I adapted new generation sequencing methods and applied them in reverse genetics approaches. My research has shown a decisive role for MNU2 in the definition of 5' monoP ends. It has also shed light on a potential 5'-3' degradation pathway
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Winger, Alison Marie. "Impact of 4-hydroxy-2-nonenal in Arabidopsis mitochondria /." Connect to this title, 2006. http://theses.library.uwa.edu.au/adt-WU2007.0121.
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Tan, Yew-Foon. "Metal-protein interactome in plant mitochondria." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0162.
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[Truncated abstract] Transition metals in the plant mitochondrion have dual roles in regulating the function of the organelle. While metals participate in mitochondrial respiratory metabolism as ligands in bioenergetic, detoxifying, and various other metabolic enzymes, a breakdown in metal homeostasis during oxidative stress can perpetuate the cycling of ROS by redox active metal ions. Large-scale studies into the duplicitous roles of metal ions in biological systems has been lacking and in this thesis, a combination of metallomics, database annotations, membrane proteomics, metal-protein interactomics, structural biology, functional assays and mass spectrometry were all used to gain a clearer insight into the involvement of metal ions in affecting plant mitochondrial function. The Arabidopsis mitochondrion was shown to contain the transition metals cobalt, copper, iron, manganese, molybdenum, and zinc. Interestingly, the redox active copper and iron represented 75% of the mitochondrial metallome and these metal species were revealed to be highly labile during oxidative stress suggesting a possible contribution of metal-catalysed oxidation (MCO) in the damage of biological macromolecules. Bioinformatic analysis of metalloproteins predicted and experimentally determined to be mitochondrially localised revealed that metal ion transporters are poorly characterised. An in-depth proteomic analysis of the membrane proteome was conducted on mitochondria isolated from unstressed and stressed cell cultures resulted in the identification of stress-responsive as well as potential metal ion transporters. Also, many of the annotated metalloproteins predicted to be mitochondrial lack experimental evidence for subcellular localisation. ... However, based on evidence in the literature, it was hypothesised that metal-interacting sites may be the targets for MCO due to their affinity for metal ions. Attempts were made to identify the site specificity of MCO on mitochondrial proteins but no carbonyl sites could be found owing to technical problems associated with non-specific binding of proteins to the enrichment resin and low abundance of the labelled protein carbonyls. The use of the model protein BSA showed that protein oxidation occurs in clusters and the use of model peptides demonstrated that the ability of amino acid residues to complex metal ions is important in dictating susceptibility to MCO. Further experimental verification for the site specificity of MCO is required to determine the consequences of MCO on mitochondrial protein function. Overall, this thesis provided a large-scale analysis of the contributions of metal ions to mitochondrial respiratory metabolism with an emphasis on metal ion induced toxicity. Using multi-facetted approaches, an insight into the dynamic nature of mitochondrial metal homeostasis, stress responsive transporters, the interactions of metal ions with mitochondrial proteins and the possible mechanism in which proteins are specifically oxidised by MCO has been uncovered paving the way for future focused studies characterising the consequences of oxidative stress on specific proteins and their function.
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Lee, Alex Chun Pong. "Dynamics of the plant mitochondrial proteome : towards the understanding of metabolic networks." University of Western Australia. School of Biomedical and Chemical Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0181.
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[Truncated abstract] The mitochondrion is the energy powerhouse that provide energy to many metabolic functions in the form of ATP. Mitochondria in plants are also known to carry out a variety of other important biochemical processes within the cell, including the anaplerotic function of tricarboxylic acid (TCA) cycle, one-carbon metabolism and portions of photorespiration. Dynamics of the mitochondrial proteome in plants underlies fundamental differences in the roles of these organelles under different developmental and environmental conditions. A quantitative comparative proteomic approach was carried out to analyze mitochondria isolated from non-photosynthetic models, cell culture and root, and compared them to mitochondria isolated from photosynthetic shoots. The glycinedependent respiration rate and the protein abundance of the photorespiratory apparatus was found to be higher in shoot than cell culture and root mitochondria. Also, there were major differences in the abundance and/or activities of enzymes in the TCA cycle between the three systems examined. The metabolic pathways that relied on the supply of intermediates from TCA cycle and photorespiration were also altered, namely cysteine, formate and one-carbon metabolism, as well as amino acid metabolism focused on 2-oxoglutarate generation, and branched-chain amino acids degradation. To further provide insight into the extent of mitochondrial heterogeneity in plants, mitochondria isolated from six organ/cell types, leaf, root, cell culture, flower, stem and silique were analyzed. Of the 251 protein spots on a 2D-gel of the mitochondrial soluble/matrix fraction, the abundance of 213 spots were significantly varied between different samples. Identification of these spots revealed a non-redundant set of 79 proteins which were differentially expressed between organ/cell types. ... Importantly, posttranslational modifications played a significant role in the dynamics of the leaf mitochondrial proteome during the diurnal cycle. Overall, these findings indicated that the mitochondrial proteome is dynamic in order to fulfil different functional and physiological requirements in response to organspecific growth and changes in the external environments. These results also indicated that the majority of the changes in the mitochondrial proteome occurred in the matrix and suggested differences in substrate choice/availability in various plant organs and during the diurnal cycle. Further, these analyses demonstrate that, while mitochondrial proteins are regulated transcriptionally by the nucleus, post-transcriptional regulation and/or post-translational modifications play a vital role in modulating the activation state and/or regulation of proteins in key biochemical pathways in plant mitochondria. The integration of proteomics data with respiratory measurements, enzyme assays and transcript datasets will allow the identification of organ-enhanced and/or light/darkresponsive metabolic pathways as well as providing potential targets for reverse genetic approaches for further functional analysis of plant mitochondria.
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Winger, Alison Marie. "Impact of 4-hydroxy-2-nonenal in Arabidopsis mitochondria." University of Western Australia. Biochemistry and Molecular Biology Discipline Group, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0121.
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[Truncated abstract] A range of biotic and abiotic stresses increase levels of reactive oxygen species (ROS) in plants due to perturbations of chloroplast and mitochondrial metabolism and the generation of ROS in defence responses. The polyunsaturated fatty acids of membrane lipids are susceptible to ROS induced peroxidation yielding various aldehydes, alkenals and hydroxyalkenals including the cytotoxic compound 4-hydroxy- 2-nonenal (HNE). HNE has the potential to cause substantial oxidative damage in cells via its reactivity with sulfhydryl groups of cysteine (Cys) and lipoic acid, the imidazole group of histidine (His) and the ?-amino group of lysine (Lys) protein residues. Analysis of the components of the plant respiratory electron transport chain to HNE revealed a particular susceptibility to inhibition of activity of the alternative oxidase (Aox). Incubation with HNE prevented dimerisation of Aox protein, suggesting that one site of modification was the conserved cysteine residue involved in dimerisation and activation of this enzyme (Cys1). However, a naturally occurring isoform of Aox lacking Cys1 and unable to dimerise, LeAox1b from tomato, was equally sensitive to HNE inhibition, showing that other amino acid residues in Aox also interact with HNE and are likely responsible for inactivation of the enzyme. ... The broader impact of HNE on the whole Arabidopsis mitochondrial proteome was examined by use of various 2-dimensional gel separation techniques coupled with use of HNE-adduct antibodies. 32 proteins involved in a number of mitochondrial functions were found to be susceptible to modification by HNE, including components of the electron transport chain, the TCA cycle, as well as proteins involved amino acid metabolism and stress-responses. Implications of modification of these proteins by HNE are discussed. As HNE is produced in vivo during oxidative stress, the profile of mitochondrial targets of HNE was examined from Arabidopsis cell cultures exposed to various oxidative stress inducers. Menadione and hydrogen peroxide induced oxidative stress throughout the cell, while antimycin A initiated a mitochondrial targeted stress. A differential profile of mitochondrial proteins was observed to be modified by HNE in the various treatments. These results also showed that induction of stress within a whole cell can impact lipid peroxidation within the mitochondria. Overall, this work showed the presence and production of HNE in plant cells, and that HNE, both exogenous and endogenous, has the ability to modify a specific subset of mitochondrial proteins. In several cases this HNE modification was shown to have functional or structural consequences.
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Mahe, Laetitia. "Import of chimeric proteins into plant mitochondria." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33804.
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Cytoplasmic male sterility (CMS) in plants is associated with mitochondrial dysfunction. We have proposed in this study that the mitochondrial-encoded chimeric peptide thought to be responsible for cytoplasmic male sterility in Polima system could function as a dominant male sterility inducer when expressed in the nucleus and targeted to the mitochondria. Transgenic plants expressing such mitochondrial targeting constructs exhibited reduction of pollen production that was characterized in fertile Westar (nap ) and restored fertile Westar (pol) plants by homeotic transformation of floral organs and in male-sterile Westar (pol) plants by a reduction in pollen production with shortening of the stamens. Genetic and molecular analysis has shown that the phenotypic changes were correlated with the effective genetic transmission of the inserted transgene through female gametes. Most significantly, we have found that differences in floral morphology induced by transgene expression between pol CMS and fertile Westar plants might be related to differences in transcriptional activity of the APETALA3 MADS box gene. We suggest that the alterations in floral morphology that accompany CMS in several plant species might be due to effects of mitochondria on transcriptional activity of floral organ identity genes.
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Kay, Christopher John. "Reactions of ubiquinone in higher plant mitochondria." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37739.
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L'Homme, Yvan. "Molecular characterization of cytoplasmic male sterility in Brassica napus." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28810.
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In order to identify organizational differences between sterile Polima (pol) and fertile Campestris (cam) mitochondrial genomes that could be linked to cytoplasmic male sterility (CMS), the physical map of the pol mitochondrial genome was constructed and compared to the physical map of the cam mitochondrial genome. The only structural differences between the two genomes are confined to a region encompassed by a 4.5 kb segment, present in pol mtDNA but absent in cam mtDNA. This 4.5 kb CMS-associated pol segment contains a chimeric gene called orf224 that is cotranscribed with atpG and comprises the single mtDNA region expressed differently in fertile, sterile and fertility restored plants which makes it a good candidate for specifying the sterility trait. Sequence analysis of the pol 4.5 kb segment has shown that orf224 was the only significant open reading frame (ORF) within the segment that gives rise to abundant transcripts, strengthening the view that the orf224/atp6 gene region is conferring pol male sterility. The pol 4.5 kb segment is also present and similarly organized in the common Brassica napus nap mtDNA but the sequences flanking the two segments are unrelated. Thus, the 4.5 kb segment appears to have transposed during the evolution of the pol and nap mitochondrial genomes and appears to have been lost in the cam mitochondrial genome. Sequence analysis of the nap segment revealed the presence of an ORF related to but divergent from orf224. This open reading frame (orf222) potentially encodes a protein of 222 amino-acids with 79% homology to the predicted product of orf224. orf222 is co-transcribed with the third exon of the trans-spliced gene, nad5, and another ORF of unknown function. Expression of the orf222 gene region is tightly associated with nap CMS since the levels of orf222 transcripts are significantly reduced upon restoration while the expression of 22 other mitochondrial genes do not consistently correlate with nap CMS. Antibodies were rai
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Soole, Kathleen Lydia. "Characterisation of the NADH dehydrogenases associated with isolated plant mitochondria /." Title page, contents and summary only, 1989. http://web4.library.adelaide.edu.au/theses/09PH/09phs711.pdf.
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Buckler, Carlyn Suzanne Keith. "Miniature plant phenotype and mitochondrial porins in maize /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9946248.
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Aissa, Abdi Fatima. "Mitochondrial complex I dysfunction enhances in vitro plant organogenesis." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS136/document.
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La régénération in vitro est un processus complexe largement utilisé pour la multiplication végétative ainsi qu'en recherche fondamentale pour étudier l'organogenèse. Malgré les diverses applications de la caulogenèse in vitro, les mécanismes de régulation impliqués restent mal caractérisés. Avant le début de mon doctorat, nous avons identifié un mutant d'Arabidopsis thaliana chez lequel un défaut du complexe I de la chaîne de transport d'électrons mitochondriale (CTEm) entraîne une augmentation du taux de régénération comparé au sauvage, mesurée sur des cals issus de protoplastes. Au début de mon projet doctoral, j'ai confirmé le lien entre le dysfonctionnement respiratoire et l'augmentation des taux de régénération en utilisant un inhibiteur spécifique du complexe I appelé roténone. Pour comprendre ce phénomène, j'ai étudié les mécanismes moléculaires et biochimiques liant la respiration mitochondriale et l'organogenèse in vitro. J'ai analysé différents mutants affectés dans l'activité du complexe I et conclu que le retard de croissance qui en découle est positivement corrélé avec le taux de régénération. Pour comprendre comment les perturbations de la CTEm affectent la formation des bourgeons, j'ai comparé les profils d'expression des gènes dans des tissus mutants du complexe I et dans des cals traités avec la roténone. Les résultats obtenus montrent, d’une part, que le profil d’expression des gènes est différent chez le sauvage et chez les mutants du complexe I et, d’autre part, que la roténone induit un stress oxydatif, inhibe la prolifération cellulaire et module les régulations hormonales. J'ai confirmé que la réponse oxydative induite par la roténone est rapidement relayée dans le cytosol en utilisant un bio-senseur de l’état redox cellulaire. Nos résultats suggèrent un lien de causalité entre un stress oxydatif induit par des perturbations respiratoires et la hausse du taux de régénération. Nos travaux pointent vers des méthodes alternatives pour améliorer l'efficacité de l'organogenèse in vitro par inhibition transitoire d'activités mitochondrialesIn vitro shoot regeneration is a complex process routinely used for vegetative propagation and to study plant organogenesis. Despite multiple applications of in vitro shoot initiation, the regulatory mechanisms involved remain poorly understood. Prior to the beginning of my PhD thesis, we identified an Arabidopsis thaliana mutant in which a defect in the complex I of the mitochondrial electron transport chain (mETC) results in a higher shoot regeneration rate compared to wild type, measured on protoplast-derived calli. At the beginning of my PhD project, I confirmed the link between the respiratory defect and the shoot regeneration boost with a specific complex I inhibitor called rotenone. To understand this phenomenon, I investigated the molecular and biochemical mechanisms linking mitochondrial respiration and shoot organogenesis. For this purpose, I analyzed different mutants affected in the complex I activity and concluded that the resulting growth retardation is positively correlated with the regeneration rate. To understand how mETC perturbations promote shoot regeneration, I compared gene expression profiles in complex I mutant tissues and in calli treated with rotenone. Our data show, on the one hand, that gene expression profiles are different in complex I mutants and, on the other hand, that rotenone induces an oxidative stress, inhibits cell proliferation, and modulate hormonal regulations. I confirmed that the oxidative response induced by rotenone is rapidly relayed in the cytosol with a redox- sensitive biosensor. Altogether, our results suggest a causal link between an oxidative stress caused by respiratory impairments and shoot regeneration enhancement. Our findings point to alternative methods to promote in vitro organogenesis via transient inhibition of mitochondrial activities
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Johansson, Monika. "The role of nucleoside diphosphate kinase in plant mitochondria /." Uppsala : Dept. of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200674.pdf.
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Padovan, Anna Caterina. "The control of oxidative phosphorylation in isolated plant mitochondria /." Title page, table of contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09SB/09sbp124.pdf.
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Sarah, Caroline J. "The import of proteins into isolated higher plant mitochondria." Thesis, University of Edinburgh, 1991. http://hdl.handle.net/1842/12898.
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Investigations of plant mitochondrial protein import have been very limited and few reports exist in the literature. The work presented in this thesis describes the development of an in vitro Zea mays mitochondrial protein import system, which has enabled the import of plant nuclear-encoded mitochondrial proteins to be examined. This Z.mays import system was characterised and partially optimised with the Nicotiana plumbaginifolia manganese superoxide dismutase (MnSOD). Results suggest that the energy requirements for protein import into plant mitochondria are similar to those of Saccharomyces cerevisiae and Neurospora crassa, requiring both an energised inner mitochondrial membrane and ATP. The inclusion of 1,10-phenanthroline inhibited the processing, but not the import of MnSOD and indicated that the processing activity within Z.mays mitochondria was dependent upon the presence of metal ions. The plant mitochondrial processing protease may therefore be similar to the characterised S.cerevisiae and N.crassa matrix processing protease. The import of the Z.mays adenine nucleotide translocator (ANT) protein was then investigated. Unlike the ANT of S.cerevisiae and N. crassa, this plant ANT was synthesised as a precursor protein, which was processed upon import into mitochondria isolated from both Z.mays and Solanum tuberosum. The subsequent isolation of an S.tuberosum ANT cDNA clone PANT-1, enabled the import of a second plant ANT to be investigated. Results corroborated the findings previously obtained with the Z.mays ANT and it was therefore concluded that the import of plant ANT proteins are distinctly different from those of S.cerevisiae and N.crassa.
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Song, Daqing. "Homologous Strand Exchange and DNA Helicase Activities in Plant Mitochondria." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd931.pdf.
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Purdue, Paul Edward. "Nuclear genes and protein import into maize mitochondria." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/12812.
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Menassa, Rima. "Nuclear-mitochondrial gene interactions and mitochondrial gene expression in Brassica napus." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0018/NQ44513.pdf.
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Peters, Katrin [Verfasser]. "Characterization of the OXPHOS system in plant mitochondria / Katrin Peters." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2012. http://d-nb.info/102116738X/34.
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Smith, Anna Marie Odette. "Investigating the TCA cycle in isolated plant mitochondria using NMR." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409761.
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Moore, Ian Robert. "Development of a strategy for genetic transformation of plant mitochondria." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/11183.
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Hamel, Nancy. "Nuclear regulation of mitochondrial gene expression in Brassica napus." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27331.
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Previous studies have shown that transcriptional differences in the orf224-atp6 mitochondrial gene region are correlated with fertility restoration of the pol CMS trait by the dominant nuclear Rfp gene in Brassica napus. Recently, the recessive rfp allele, or a tightly linked gene, was found to act as a dominant gene, designated Mmt, in controlling the production of additional, smaller transcripts of two other mitochondrial loci. The results presented in this thesis reveal that Mmt-specific transcripts lack sequences found at the $5 sp prime$ end of the full-length transcripts of these loci and contain a common sequence, UUGUGG, which maps immediately downstream of their $5 sp prime$ termini. A similar sequence, UUGUUG, is found within orf224 downstream of the major Rfp-specific $5 sp prime$ transcript terminus; these hexanucleotide sequences may serve as recognition motifs in the generation of Mmt- and Rfp-specific transcripts. These results suggest that Rfp/Mmt is a novel nuclear locus affecting the expression of multiple mitochondrial gene regions, with different alleles or haplotypes affecting different mitochondrial genes.
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Zhang, Mingda. "Plant mitochondrial RNA : replicons characterization and developmentally regulated distribution." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41804.
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The structure of one member of a family of maize mitochondrial RNA replicons (or RNA plasmids), RNA b, has been characterized. It is shown that RNA b shares a 13 nucleotide sequence with the central conserved region of Cadang-Cadang viroid of coconuts which might be involved in substrate recognition by the RNA replicase during replication. RNA b likely was derived from a larger member in that family, RNA a, through co-linear deletions similar to those involved with the generation of the defective interfering (DI) elements associated with both animal and plant viruses. RNA b may represent a "selfish" RNA optimized for replication as it does not have the capacity to encode its own replicase. Mitochondrial RNA plasmids have been found not to be restricted to the S and RU cytoplasms, as previously reported. Related plasmid RNAs have been detected in maize plants with C, N and T cytoplasms as well as 13 Latin American races. They were not found, however, in teosintes, indicating that the ancestral nucleic acid from which these RNAs evolved was acquired soon after the split between teosintes and maize, before the divergence of the maize races. Distribution of the plasmid RNAs, a maize mRNA (atp6), and a mitochondrial rRNA (26S) in different organs and tissues was investigated by in situ hybridization. These results indicated that mitochondrial gene expression is subjected to an unexpected degree of both spatial and developmental regulation, and that individual mitochondrial genes are subjected to different controls. Similar results were obtained in in situ hybridization studies of Brassica floral buds. Both studies suggested that the levels of mitochondrial genes transcripts are not particularly high in the tapetal cells of both maize and Brassica anthers contrary to common belief. High levels of RNA plasmid were detected in the pollen of S maize anthers prior to pollen abortion, suggesting they might be related to the cytoplasmic male sterility (CMS) trait of S maize
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Woods, Clare A. "Respiratory carbon loss in plant tissues under environmental stress." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:829338ba-7c5a-41b8-9cdd-ead4646e161e.
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Crop productivity is a balance between carbon gain by photosynthetic assimilation of CO2 and the release of fixed carbon as CO2 via respiration. Respiration is the process by which carbohydrates are oxidised to produce ATP to fuel biochemical reactions, whilst simultaneously releasing CO2 as a by-product; therefore, increased demand for ATP or decreased efficiency of ATP production by uncoupling of the mitochondrial electron transport chain results in greater CO2 production. ATP produced by respiration is either used to support processes involved in growth or to power cell maintenance processes, such as macromolecule turnover or maintenance of membrane ion gradients. Respiration increases when plants are exposed to high temperatures; a factor that will become increasingly important as we try to maximise food production as the global climate changes. However, it is unknown if increased respiration at high temperature is necessary to provide energy to support growth, is a consequence of increased ATP consumption for maintenance processes or is due to increased mitochondrial uncoupling at high temperature. Flux measurements showed that CO2 production by excised Arabidopsis thaliana roots increases with temperature up to 37°C. Although growth also increased up to 37°C resulting in increased respiration associated with growth processes, the majority of overall CO2 production at high temperatures could be accounted for by non-growth respiration. An analysis of ATP-consuming processes demonstrated that protein turnover and maintenance of ion gradients collectively account for the majority of maintenance respiration, but that ATP consumption for the maintenance of ion gradients is quantitatively more important than protein turnover at high temperature. Furthermore, a decrease in in vivo P/O ratio at high temperature was demonstrated; the results presented suggest that this is most likely due to increased basal proton leak across the inner mitochondrial membrane. It can be concluded that increased CO2 production at high temperature results from a combination of increased ATP consumption for the maintenance of ion gradients and a decrease in coupling of the mitochondrial electron transport chain through a common mechanism of increased membrane fluidity and ion leak.
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Clifton, Rachel. "The alternative oxidase gene family in arabidopsis : insights from a transcriptomic study /." Connect to this title, 2005. http://theses.library.uwa.edu.au/adt-WU2006.0004.
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Carrillo, Catherine. "RNA splicing and editing of group II introns in flowering plant mitochondria." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0016/NQ57026.pdf.
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Rayapuram, Naganand. "Insights into understanding the maturation of c-type cytochromes in plant mitochondria." Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13127.
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Scherban, Donna Michele 1954. "LIPOXYGENASE ACTIVITY ASSOCIATED WITH CYANIDE-INSENSITIVE OXYGEN UPTAKE IN MITOCHONDRIAL FRACTIONS FROM SEEDLINGS OF GLYCINE MAX L." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276512.
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Soybean seeds are known to contain high levels of lipoxygenase activity, especially during early stages of germination. Crude mitochondrial fractions from germinating soybeans also have been shown to exhibit high rates of cyanide-insensitive oxygen uptake. These results show the effects of successive discontinuous PercollR density gradients on mitochondrial fractions from 2 day old soybean seeds as judged by polarographic studies and Ouchterlony double diffusion. Axis mitochondria exhibited totally cyanide-sensitive oxygen uptake after two gradients and cotyledon mitochondria exhibited from none to 11% cyanide-insensitive oxygen uptake after three gradients. Mitochondrial fractions which were assayed for lipoxygenase with double diffusion exhibited positive results with fractions that showed cyanide-insensitive oxygen uptake and negative results with cyanide-sensitive mitochondria. These results suggest that lipoxygenase can loosely associate with the mitochondrial membrane and that gradient centrifugation can purify mitochondria free of both lipoxygenase and cyanide-insensitive oxygen uptake.
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Thornsberry, Jeffry M. "Mitochondrial-chloroplast interactions : studies using the NCS mutants of maize /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9946304.
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Chaulk, Christine Annie 1964. "Chromosome number, fertility, and mitochondrial genome of backcross populations derived from Medicago sativa x Medicago dzhawakhetica hybrids." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277157.
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Backcross populations (BC) from Medicago sativa L. x M. dzhawakhetica Bordz. hybrids were analyzed for chromosome number, fertility and morphological characteristics. Previously obtained F1 hybrids were recovered when diploid (2n = 2x = 16) M. sativa was crossed with tetraploid (2n = 4x = 32) M. dzhawakhetica. Resulting F1 hybrids were triploid (2n = 3x = 24), completely male sterile and had low levels of female fertility. Subsequent populations were obtained by successive backcrossing to unrelated (4x) M. sativa clones. The BC1 plants were pentaploid (2n = 5x = 40) and both male and female fertile. BC2 populations had chromosome numbers ranging from 2n = 32 to 48, and most plants (94% were male and female fertile. BC3 populations were tetraploid (2n = 32) or near tetraploid (2n = 33) and were morphologically similar to M. sativa. Preliminary analysis of mitochondrial nucleic acids by agarose gel electrophoresis, indicated biparental inheritance of this organelle in the F1 hybrids; however, further analysis provided inconclusive results.
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Crichton, P. G. "Structure-function analysis of the plant alternative oxidase expressed in Schizosaccharomyces pombe mitochondria." Thesis, University of Sussex, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549668.
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The alternative oxidase (AOX) is a terminal respiratory oxidase found in the mitochondria ()f higher plants, many fungi as well as several protists. Its activity is non-protonmotive and therefore decreases the efficiency of mitochondrial energy transduction. Structural and mechanistic insights into AOX regulation and catalysis are therefore important for a I'undamental understanding of mitochondrial energy metabolism. Given that some parasites. unlike their mammalian hosts, are dependent upon an AOX, such information may also facilitate the design of novel AOX inhibitors as potential chemotherapeutic drugs. The work presented in this thesis comprises a biochemical analysis of plant AOX proteins expressed in isolated yeast mitochondria using a previously established heterologous system. An initial characterisation of isolated S. pombe mitochondria reveals oxygen uptake activity dependent upon the presence of ethanol. This activity is shown to be the result of a novel matrix-located alcohol dehydrogenase that regenerates NADH, which is subsequently oxidised by the respiratory chain. Data obtained using a system kinetic approach provide further insight into the unusual behaviour of this respiratory pathway. The relative activities of site-specific mutants of the Sauromatum guttatum AOX have been assessed in isolated yeast mitochondria and characterised with respect to substrate and inhibitor affinity. The mutation of two residues is shown to affect the apparent affinity of AOX for oxygen. A potential influence of these residues on the active site of AOX is discussed. Following the expression of a second AOX isozyme (AOXla from Arabidopsis thaliana), respiratory analysis with isolated yeast mitochondria and mitochondrial membranes indicates that the S. guttatum AOX is the first plant isozyme identified that is not regulated by organic acids and appears to be in a constitutively active state. A bioinformatic study implicates novel residues, other than established regulatory cysteines, in the interaction with organic acids and provides a framework for structural hypotheses
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Rugen, Nils [Verfasser]. "From single proteins to supercomplexes : a proteomic view on plant mitochondria / Nils Rugen." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2019. http://d-nb.info/1204458707/34.
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Branch, Traci L. "Pattern and distribution of RNA editing in land plant RBCL and NAD5 transcripts." Akron, OH : University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1163792182.
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Thesis (M.S.)--University of Akron, Dept. of Biology, 2006."December, 2006." Title from electronic thesis title page (viewed 12/31/2008) Advisor, Robert Joel Duff; Committee members, Richard Londraville, Francisco B. Moore, Amy Milsted; Department Chair, Bruce Cushing; Dean of the College, Ronald F. Levant; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Mower, Jeffrey P. "The weird world of plant mitochondria transient mutators, horizontal gene transfer, and RNA editing /." [Bloomington, Ind.] : Indiana University, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3204308.
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Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2006.Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0102. Adviser: Jeffrey D. Palmer. "Title from dissertation home page (viewed Feb. 21, 2007)."
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Auchincloss, Andrea Helen. "Transcription initiation sites on the soybean mitochondrial genome." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63914.
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Formanová, Nataša. "A complex synthesizing the maize mitochondrial plasmid RNA b /." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=68173.
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RNA b is the most abundant member of a family of autonomously replicating single- and double-stranded RNA plasmids found in mitochondria of several maize races. The extent to which this molecule associates in vivo with proteins was investigated by both rate zonal and CsCl equilibrium density gradient centrifugations of clarified lysate of mitochondria from maize plants with the S-type cytoplasm. A soluble endogenous complex of RNA b, responsible for synthesis of the more abundant (+) RNA b strand in in vitro conditions (in mitochondrial lysate), was identified. The complex had a density of 1.49 g/cm$ sp3$ but a surprisingly low sedimentation coefficient, only slightly larger than the naked RNA b. Only a minor fraction of RNA b molecules were bound in the complex; the majority of RNA b sedimented as naked RNA molecules. Complexes synthesizing other, less abundant, maize RNA plasmids were not identified. However, in vitro synthesis of all RNA plasmid species in mitochondrial lysate was resistant to heparin, suggesting that in all cases preformed RdRp-RNA template complexes, capable of elongating in vivo preinitiated RNA plasmid strands, were present.
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Barreto, Pedro Paulo 1988. "Alterações no metabolismo energético provocadas pela superexpressão da proteína desacopladora mitocondrial 1 (UCP1) em tabaco induzem biogênese mitocondrial e resposta global a estresses : Alterations on energy metabolism caused by mitochondrial uncoupling protein 1 (UCP1) overexpression in tobacco induce mitochondrial biogenesis and global stress response." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317202.
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Orientador: Paulo ArrudaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A proteína desacopladora mitocondrial 1 (UCP1) é uma proteína mitocondrial codificada pelo núcleo capaz de desacoplar o gradiente eletroquímico usado para a síntese de ATP, dissipando a energia na forma de calor. A descoberta de homólogos e ortólogos da UCP1, sugere outros papéis fisiológicos para estas proteínas. As UCPs podem servir como uma válvula de escape, diminuindo a força protonmotiva (PMF) e reduzindo a produção de ROS em condições desfavoráveis. Plantas superexpressando UCPs se desenvolvem melhor quando submetidas a estresses bióticos e abióticos. Estas plantas demonstraram diminuição na produção de ROS, alteração no estado redox celular, além de um aumento no metabolismo energético e na fotossíntese. Neste trabalho nós investigamos os mecanismos moleculares envolvidos no metabolismo energético celular e resposta a estresses em plantas de tabaco superexpressando a UCP1 de A. thaliana. Demonstramos, através de análises moleculares e genômicas, que a superexpressão da UCP1 é capaz de provocar o aumento na respiração desacoplada em mitocôndrias isoladas, diminuir o conteúdo de ATP intracelular, e desencadear um processo de sinalização retrógrada que resulta na indução de genes mitocondriais e genes responsivos a estresses. Esta sinalização retrógrada resultou na indução do processo de biogênese mitocondrial verificado pelo aumento no número e área mitocondrial por célula, além de alterações morfológicas nestas organelas. O processo de biogênese mitocondrial nestas plantas é acompanhado pelo aumento na expressão de um grande número de genes responsivos a estresses, o que resulta no melhor desempenho e reduzida produção de ROS mitocondrial quando submetidas a estresses abióticos. A análise detalhada do transcriptoma de plantas superexpressando UCP1 em comparação com plantas selvagens demonstrou uma forte conexão entre os metabolismos mitocondrial, citoplasmático e cloroplástico para compensar as alterações provocadas pelo aumento na atividade da UCP1. Um grande número de fatores de transcrição ainda não caracterizados foram identificados e podem representar bons alvos para investigações futuras a respeito da regulação da biogênese mitocondrial e do metabolismo energético em plantas. Os resultados contidos nesta tese nos permitem melhor compreender a flexibilidade do metabolismo energético em plantas e identificar possíveis reguladores do processo de biogênese mitocondrial e resposta a estresses em plantas
Abstract: The mitochondrial uncoupling protein 1 (UCP1) is a nuclear-encoded mitochondrial protein capable of uncouple the electrochemical gradient used for ATP synthesis, dissipating energy as heat. The discovery of UCP1 homologues, and its corresponding orthologues suggest diverse physiological functions for these proteins. UCPs may serve as an escape valve, decreasing the proton motive force (PMF) and preventing ROS production under unfavorable conditions. Plants overexpressing UCPs perform better under biotic and abiotic stresses. These plants show diminished ROS production, alteration of cell redox homeostasis, increased energy metabolism and photosynthesis. In this work we investigated the molecular mechanisms underlying cell energy metabolism and stress response in tobacco plants overexpressing an Arabidopsis thaliana UCP1. We demonstrated through molecular, cellular and genomic tools that UCP1 overexpressing plants is capable of increasing uncoupled respiration of isolated mitochondria, decrease intracellular ATP levels, and trigger a retrograde signaling that resulted in a broad induction of mitochondrial and stress response genes. The retrograde signaling resulted in the induction of mitochondrial biogenesis verified by increased mitochondrial number, area and alterations on mitochondrial morphology. The increased mitochondrial biogenesis in these plants accompanied by the broad increase in the expression of stress responsive genes, may be responsible for the diminished ROS production and the better performance of these plants when submitted to several abiotic stresses. We also performed a detailed analysis of the transcriptome expression of the UCP1 overexpressing plants as compared with the wild type plants. We verified that the UCP1 overexpressing plants exhibited a tight connection between mitochondrial, cytoplasm and chloroplast energy metabolism to accommodate the alterations caused by the increased UCP1 activity. A number of uncharacterized transcription factors seem to be good targets for future investigations on the regulation of plant mitochondrial biogenesis and energy metabolism. The results presented in this work allowed a better understanding of the flexibility of energy metabolism in plants, and the use of this mechanism to identify possible regulators of plant mitochondrial biogenesis and stress response
Doutorado
Bioinformatica
Doutor em Genetica e Biologia Molecular
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Calixte, Sophie. "RNA processing of the ccmFn-rps1 and rpl5-Psirps14-cox3 loci in wheat mitochondria during seedling development." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27580.
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Plant mitochondria possess a gene expression system in which post-transcriptional events, such as transcript end maturation and turnover mechanisms play a key role in regulating the transcriptome. In addition, during early developmental stages of embryo germination, differing transcript profiles have been seen. This research focuses on two loci in wheat mitochondria, ccmFn-rps1 and rpl5-Psirps14-cox3, to elucidate the transcription and post-transcriptional events involved in their expression. Northern analysis of the ccmFN-rps1 genes during early seed-to-seedling development reveals a 3.2 kb primary transcript and a 2.7 kb bicistronic mRNA. A 0.7 kb monocistronic rps1 mRNA is detectable up to 2d but there is no detectable monocistronic ccmFN transcript during the stages examined. Transcript ends were mapped using circular-RT-PCR and phosphatase treatment at three different developmental stages and revealed two processing sites as well as a single 3' end common to all three transcripts. The 5' ends of the processed rps1 transcripts are heterogeneous and do not always include the start codon, questioning the rps1 transcript functionality.
Gene order varies between plant species due to the high recombination rate in mitochondrial genomes, as is seen for rpl5-Psirps14 in wheat and rice. In both plants, the functional rps14 gene is encoded in the nucleus and the mitochondrial rps14 copy is a pseudogene. In wheat, rpl5-Psirps14 are co-transcribed with cox3 as two RNA species of 3.5 kb and 2.7 kb at 24hr post-imbibition and exhibit developmentally-specific differences in abundance in seedlings. Two promoter regions were mapped in wheat upstream of rpl5 and both transcripts have the same 3' end. In rice 24hr and 6d however, rpl5-Psirps14 are co-transcribed as a 1.4 kb bicistronic mRNA. This presumably reflects the different regulatory signals used in different species. In addition, rpl5 has been subject to several independent gene transfers to the nucleus in the cereal lineages. For example, there is a functional copy of rpl5 in the mitochondria and the nucleus in wheat but it is absent from the mitochondria in rye and maize. In oat mitochondria, rpl5 appears to be a pseudogene and in barley, rearrangements at the 3' end and low transcript levels question its functionality.
The characterization of transcription initiation sites, processing sites and 3' ends for these two loci reflect the relaxed nature and flexibility of signals exploited by plant mitochondria. This research supports the significant role of post-transcriptional events in the regulation of gene expression in plant mitochondria.
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Salone, Véronique. "Identification du facteur catalytique du processus d'edition des ARN des organites chez les plantes = Identification of the RNA editing enzyme in plant organelles." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0199.
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Il serait opportun de débuter cette introduction en donnant une définition claire du processus d'édition des ARN, mais c'est aussi un exercice périlleux car le terme d'édition des ARN a été utilisé dans la littérature pour décrire une multitude de processus biochimiques différents et la distinction entre les processus d'édition ou de modification est parfois confuse. Le terme dédition des ARN a été utilisé pour la première fois en 1986 pour décrire linsertion de 4 résidus uridines dans le transcrit mitochondrial coxII chez le trypanosome (Benne et al., 1986). La communauté scientifique était sceptique et on a alors pensé que ce mécanisme était sans doute spécifique à ce « drôle » de protozoaire. Puis, rapidement, l'édition d'ARNm a été décrite chez de nombreux organismes eucaryotes, soit pour expliquer des processus d'insertions ou de délétions de nucléotides (qui altèrent le nombre de nucléotides contenus dans la molécule d'ARN) soit pour décrire des conversions ou des remplacements de nucléotides (qui altèrent l'identité des nucléotides contenus dans la molécule d'ARN). Plus tard, le terme d'édition des ARN a été utilisé pour décrire des désaminations (le plus fréquemment C-en-U, et A-en-I) survenant dans les ARNt et les ARNr d'organismes eucaryotes et procaryotes, mais aussi des modifications mineures des résidus (comme l'ajout de groupement méthyl). De même la polyadénylation de la partie 3' de certains ARNt est aussi communément appelée processus d'édition des ARN. Enfin, un phénomène d'édition cotranscriptionnel des ARN lié au « patinage » de l'ARN polymérase a également été mis en évidence chez certains virus.
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Mileshina-Nepomnyashchikh, Daria. "Biotechnological approaches for the manupulation of the genetic information in the mitochondria of plant and human cells." Strasbourg, 2009. http://www.theses.fr/2009STRA6052.
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Les génomes mitochondriaux diffèrent dans leur structure, leur taille et leurs processus fonctionnels. Leur expression complexe est difficile à disséquer. Les maladies dues à des mutations dans l'ADN mitochondrial sont très répandues et la génétique des mitochondries a une grande importance agronomique. Il y a donc un fort besoin de manipuler le système génétique de ces organelles mais aucune approche n'a abouti à une méthodologie de transformation mitochondriale chez les mammifères et les plantes. Les principaux problèmes sont la transfection des organelles et le maintien de l'ADN transfecté. Les mitochondries isolées peuvent cependant importer de l'ADN. Sur la base de ce mécanisme, nous avons exploré des stratégies pour maintenir l'ADN exogène dans les organelles. Dans les mitochondries humaines, la recombinaison est rare. Nous avons ainsi tenté d'élaborer des constructions capables de se comporter comme des réplicons autonomes. Chez les plantes, la recombinaison homologue façonne le génome mitochondrial et nous avons réussi à intégrer une séquence-rapportrice dans l'ADN génomique des organelles. La compétence pour l'import d'ADN est susceptible d'être exploitable in vivo. Nous avons utilisé des vésicules mitochondriotropiques pour délivrer nos constructions à proximité des mitochondries dans des cellules humaines ou végétales. Suivant une autre stratégie, notre équipe a montré qu'un ARN passager associé à un mime d'ARNt et exprimé à partir d'un transgène nucléaire est importé dans les mitochondries des cellules végétales. Nous avons tenté d'analyser la fonctionnalité de l'ARN passager dans les mitochondries par des tests d'édition in vitro, in organello et in vivoMitochondrial genomes from various organisms differ in their structure, size and functional processes. Their complex expression is difficult to dissect. Diseases due to mutations in the mitochondrial DNA are widespread and mitochondrial genetics have a high agronomic relevance. There are thus strong needs to manipulate the mitochondrial genetic system in mammals and plants, but none of the attempted approaches has led to a mitochondrial transformation methodology in these organisms. The main problems to solve are the transfection of the organelles and the maintenance of the transfected DNA. Earlier experiments showed that isolated mitochondria can import DNA. Based on this mechanism, we have explored distinct strategies to achieve maintenance of exogenous DNA in human and plant organelles. In human mitochondria, recombination is a rare event. We have thus attempted to build and test constructs able to behave as autonomous replicons. In plants, homologous recombination is believed to shape the mitochondrial genome and we succeeded in integrating a reporter sequence into the organelle genomic DNA. The DNA import competence might be exploitable in vivo. We therefore used currently developed mitochondriotropic vesicles (DQAsomes, liposomes) to try and deliver our constructs to the vicinity of the mitochondria in human or plant cells. In a further, distinct strategy, our group showed that a passenger RNA associated with a tRNA mimic and expressed from a nuclear transgene is imported into the mitochondria of the transformed plant cells. We have tried to analyse the functionality of the passenger RNA in the mitochondria through in vitro, in organello and in vivo editing tests
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Leach, Graeme Richard. "Regulation of respiratory activity in plant mitochondria : interplay between the quinone-reducing and quinol-oxidising pathways." Thesis, University of Sussex, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320417.
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Abrecht, Helge. "Purification, functional and structural characterization of two voltage-dependent anion-selective channel isoforms of plant seed mitochondria." Doctoral thesis, Universite Libre de Bruxelles, 2001. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211672.
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Clifton, Rachel. "The alternative oxidase gene family in arabidopsis : insights from a transcriptomic study." University of Western Australia. Biochemistry and Molecular Biology Discipline Group, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0004.
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[Truncated abstract] Mitochondria play an essential role in diverse metabolic pathways in plants. Their primary roles are the oxidation of organic acids via the tricarboxylic acid cycle and the synthesis of ATP coupled to the transfer of electrons from reduced NAD+ to oxygen via the electron transport chain. Plant mitochondria also contain nonphosphorylating bypasses of the respiratory chain, catalysed by the alternative oxidase (AOX), type II NAD(P)H dehydrogenases (NDHs) and uncoupling proteins (UCPs). Each of these components bypasses energy conservation by either circumventing the formation or utilization of the electrochemical proton gradient, and each is encoded by a small gene family in Arabidopsis. It is proposed that the alterative pathways are likely to be involved in balancing cellular redox and energy status and in minimizing the production of ROS generated by over-reduction of basal respiratory chain components. Furthermore the alternative respiratory pathways are thought to play a role in plant responses to stress. In this study a transcriptomic approach was taken to investigate the role of the alternative respiratory pathways in Arabidopsis, with a focus on elucidating the role and regulation of the AOX gene family. Analysis of the expression of the five AOX genes in Arabidopsis over development and in a range of tissues revealed a unique spatiotemporal expression pattern for each gene. Expression profiling using quantitative RT-PCR, MPSS and microarrays detected an abundance of the AOX1a transcript throughout the plant and over development. The expression patterns of other AOX genes provide insight into their putative roles, AOX1b was expressed predominantly in the flower, AOX1d was particularly abundant in senescing leaves and AOX2 expression was only observed in the seed.
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Branch, Traci L. "Pattern and distribution of RNA editing in land plant rbcL and nad5 transcripts." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1163792182.
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Naumann, Julia, Karsten Salomo, Joshua P. Der, Eric K. Wafula, Jay F. Bolin, Erika Maass, Lena Frenzke, et al. "Single-Copy Nuclear Genes Place Haustorial Hydnoraceae within Piperales and Reveal a Cretaceous Origin of Multiple Parasitic Angiosperm Lineages." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-132144.
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Extreme haustorial parasites have long captured the interest of naturalists and scientists with their greatly reduced and highly specialized morphology. Along with the reduction or loss of photosynthesis, the plastid genome often decays as photosynthetic genes are released from selective constraint. This makes it challenging to use traditional plastid genes for parasitic plant phylogenetics, and has driven the search for alternative phylogenetic and molecular evolutionary markers. Thus, evolutionary studies, such as molecular clock-based age estimates, are not yet available for all parasitic lineages. In the present study, we extracted 14 nuclear single copy genes (nSCG) from Illumina transcriptome data from one of the “strangest plants in the world”, Hydnora visseri (Hydnoraceae). A ~15,000 character molecular dataset, based on all three genomic compartments, shows the utility of nSCG for reconstructing phylogenetic relationships in parasitic lineages. A relaxed molecular clock approach with the same multi-locus dataset, revealed an ancient age of ~91 MYA for Hydnoraceae. We then estimated the stem ages of all independently originated parasitic angiosperm lineages using a published dataset, which also revealed a Cretaceous origin for Balanophoraceae, Cynomoriaceae and Apodanthaceae. With the exception of Santalales, older parasite lineages tend to be more specialized with respect to trophic level and have lower species diversity. We thus propose the “temporal specialization hypothesis” (TSH) implementing multiple independent specialization processes over time during parasitic angiosperm evolution.
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Sekharan, Soja. "Aged soybean (Glycine max [L.] Merrill) seeds their physiology and vigor assessment /." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1135809134.
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Castandet, Benoît. "Mécanisme et origine de l’édition des ARN messagers des mitochondries de plante." Thesis, Bordeaux 2, 2010. http://www.theses.fr/2010BOR21789/document.
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L’édition des ARN est une exception à la règle de la biologie moléculaire qui stipule que l’information codée par le gène se trouve fidèlement transmise à la protéine. Dans les mitochondries de plante, elle procède par conversion de centaines de cytosines en uraciles par désamination, principalement dans les ARNm. Afin de comprendre le mode de reconnaissance des cytosines par la machinerie d’édition nous avons systématiquement vérifié l’importance des nucléotides -1 et +1 entourant la cytosine cible dans l’édition des transcrits cox2 de blé. Sur cette base, les sites d'édition peuvent être classés en quatre familles: (a) dépendance du résidu +1, (b) dépendance du résidu -1, (c) dépendance des deux résidus et (d) indépendance. Nous avons d’autre part mis en évidence des effets à distance sur le taux de la réaction d’édition, montrant ainsi que certains sites ne sont pas autonomes pour la réaction. L'ensemble des observations nous révèle que le devenir des transcrits a une influence sur l'efficacité de l’édition. Pour le vérifier nous avons construit des gènes cox2 et rps10 dépourvus d'introns. L’efficacité d’édition des transcrits qui ne sont pas soumis à l'épissage est grandement réduite par rapport aux transcrits sauvages, ce qui renforce l’idée que les mécanismes de maturation doivent être interconnectés dans les mitochondries de plante. D’autre part, nous avons montré que l’édition de certains sites introniques pouvait être indispensable à la maturation des transcrits en rétablissant des structures nécessaires à l’épissage. L’exploration de la mécanistique de l’épissage des introns mitochondriaux nous a conduit à mettre au point un test de trans-épissage in organello. Ce test doit permettre de valider expérimentalement les hypothèses ayant trait à la reconnaissance des transcrits et de vérifier le rôle de l’édition dans ce mécanisme. Enfin, la mise en relation de l’édition avec d’autres phénomènes physiologiques touchant les organelles, comme la stérilité mâle cytoplasmique, nous a permis de développer une hypothèse permettant d’expliquer l’émergence et le maintien au cours de l’évolution de ce phénomène chez les plantes. Nous proposons que le conflit nucléo-cytoplasmique a constitué l’élément moteur pour l’apparition de l’édition en permettant l’installation de mutations T en C au niveau de la mitochondrie. La réponse nucléaire a été la correction de ces mutations sur l’ARN mitochondrial, aboutissant à ce que nous appelons aujourd'hui l’édition des ARNRNA editing is an exception to the central dogma of molecular biology which states that the information encoded by the gene is faithfully transmitted to the protein. The plant mitochondrial transcriptome undergoes hundreds of specific C-to-U changes by RNA editing, mainly in mRNAs. To understand the mechanism used by the plant to select the C targets on the transcript, we studied the role of the neighbors -1 and +1 nucleotides in wheat cox2 editing sites. Under this scheme, four different recognition patterns can be distinguished: (a) +1 dependency (b) -1 dependency (c) +1/-1 dependency and (d) no dependency on nearest neighbor residues. An important observation was that distal elements can influence the editing efficiency, indicating that some sites are not autonomous for the reaction. We propose that these results could be a consequence of the fate of transcripts during the different maturation steps. To test this hypothesis, we constructed intronless cox2 and rps10 genes. RNA editing was strongly reduced in these constructs, suggesting that efficient RNA processing may require a close interaction of factors engaged in different maturation processes. Our results on editing events in non coding region, particularly in introns, indicate that editing is essential for splicing by remodeling the secondary structure required to excise the intron. To gain insight into the splicing mechanism for scattered mitochondrial genes, we have settled an in organello trans-splicing assay. By this way, it should be possible to decipher the molecular determinants of the reaction and the eventual role of RNA editing in this process. Finally, we proposed a new hypothesis explaining the origin and evolution of RNA editing in plant mitochondria. We assume that the nucleo-cytoplasmic conflict was the driving force allowing the settlement of T-to-C mutations in the mitochondrial genome. The nuclear response was the correction of these mutations on the RNA, i.e. RNA editing
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Weerakoon, Tasmeen Shiny. "Investigation of a putative mitochondrial Twin Arginine Translocation pathway in Arabidopsis thaliana." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1501256746410956.
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Naumann, Julia, Karsten Salomo, Joshua P. Der, Eric K. Wafula, Jay F. Bolin, Erika Maass, Lena Frenzke, et al. "Single-Copy Nuclear Genes Place Haustorial Hydnoraceae within Piperales and Reveal a Cretaceous Origin of Multiple Parasitic Angiosperm Lineages." Public Library of Science, 2013. https://tud.qucosa.de/id/qucosa%3A27425.
Full textAbstract:
Extreme haustorial parasites have long captured the interest of naturalists and scientists with their greatly reduced and highly specialized morphology. Along with the reduction or loss of photosynthesis, the plastid genome often decays as photosynthetic genes are released from selective constraint. This makes it challenging to use traditional plastid genes for parasitic plant phylogenetics, and has driven the search for alternative phylogenetic and molecular evolutionary markers. Thus, evolutionary studies, such as molecular clock-based age estimates, are not yet available for all parasitic lineages. In the present study, we extracted 14 nuclear single copy genes (nSCG) from Illumina transcriptome data from one of the “strangest plants in the world”, Hydnora visseri (Hydnoraceae). A ~15,000 character molecular dataset, based on all three genomic compartments, shows the utility of nSCG for reconstructing phylogenetic relationships in parasitic lineages. A relaxed molecular clock approach with the same multi-locus dataset, revealed an ancient age of ~91 MYA for Hydnoraceae. We then estimated the stem ages of all independently originated parasitic angiosperm lineages using a published dataset, which also revealed a Cretaceous origin for Balanophoraceae, Cynomoriaceae and Apodanthaceae. With the exception of Santalales, older parasite lineages tend to be more specialized with respect to trophic level and have lower species diversity. We thus propose the “temporal specialization hypothesis” (TSH) implementing multiple independent specialization processes over time during parasitic angiosperm evolution.
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Manzoor, Hamid. "Calcium signaling in plant defense : involvement of subcellular compartments and glutamate receptors." Phd thesis, Université de Bourgogne, 2012. http://tel.archives-ouvertes.fr/tel-00990044.
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Plants do not display an adaptive immune system but express an efficient innate immune system defending them by inducing sophisticated multilevel defense responses against different potential pathogens. Indeed, plant immune responses are triggered upon the detection of many common pathogen- or microbe-associated molecular patterns (PAMPs/MAMPs) through specific pattern-recognition receptors (PRRs) and/or pathogen- or plant-derived signal molecules called elicitors. Cryptogein (Cry) and oligogalacturonides (OGs) are well known elicitors of defense reactions and their recognition induce a Ca2+-dependent signaling pathway: Ca2+ influx and subsequent free cytosolic [Ca2+] ([Ca2+]cyt) variations are earliest steps to trigger downstream plant defense signaling. Here we have demonstrated that elicitor-induced Ca2+ signaling in tobacco also takes place in mitochondria and chloroplasts. Pharmacological studies indicated that IP3-channels play an important role in the regulation of Ca2+ signaling in mitochondria and chloroplasts. Mitochondrial respiration and energy dissipation mechanisms in chloroplasts are partly controlled by [Ca2+] in these organelles. Moreover, using pharmacological and genetic approaches, our data demonstrated that glutamate receptors homologs (GLRs) participate in OGs-mediated Ca2+ signaling in Arabidopsis. GLRs partly control OGs-induced nitric oxide (NO) production, reactive oxygen species (ROS) production and expression of defense-related genes. Importantly, plants treated with GLRs antagonists exhibited compromised resistance to necrotrophic fungal pathogen, Botrytis cinerea and biotrophic oomycete, Hyaloperonospora arabidopsidis. Analysis of Atglr single mutants revealed the important contribution of AtGLR3.3 in resistance against H. arabidopsidis. Moreover, striking similarities in gene expression levels were observed after OGs elicitation/H. arabidopsidis infection. Finally, transcriptomic analysis demonstrated that about 60 % of the total OGs-modulated genes modified their expression in GLRs-dependent manner. These GLRs-dependent genes belong to different functional categories including the category "responses to biotic stresses". Taken together, these data provide strong evidences of 1) elicitor-induced Ca2+ signaling in mitochondria and chloroplasts in tobacco and 2) the regulation of elicitor/pathogen mediated plant defense signaling pathways through GLRs in Arabidopsis thaliana
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Floro, Eric R. "Mitochondrial heteroplasmy in Mimulus guttatus." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1302199999.
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