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Renner, Swen Christoph. "Structure and diversity of cloud forest bird communities in Alta Verapaz, Guatemala, and implications for conservation." Doctoral thesis, [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969959478.
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Bayoudh, Aïcha Souami Lakhdar. "Récit et discours dans le Kitāb al-imtāʻ wa-al-muʼānasa d'Abū Ḥayyān at-Tawḥīdī, 310-320/922-932 - 414/1023 /". Lille : Atelier national de reproduction des thèses, 2007. http://catalogue.bnf.fr/ark:/12148/cb411537861.
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Bayoudh, Aïcha. "Récit et discours dans le Kitāb al-imtāʾwa l-muʾānasa d'Abū Ḥayyān at-Tawḥīdī (310-320/922-932 - 414/1023)". Paris 3, 2003. http://www.theses.fr/2003PA030147.
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Le savoir commun est une source de communication dans l'existence quotidienne. Il l'est plus particulièrement dans les cercles intellectuels du IV/X s. Il était donc indispensable pour l'homme de lettres d'y participer pour combler son besoin de discussion et pour affirmer sa notoriété intellectuelle parmi ses émules. Pour Abû Hayyân at-Tawhîdî, il suffit de dépasser les obstacles de discrimination socio-culturelle et religieuse pour révéler un esprit libre, déterminé à dénoncer le mal pour instaurer le bien. De toute évidence, son but est éducatif. Il est clair ensuite que le rôle de l'élite intellectuelle est de s'interroger sur tous les phénomènes de la vie pour servir la sagesse et répandre l'éthique. C'est ce qui permet d'instaurer un équilibre parfait entre la passion et la raison. Or, une telle tâche ne peut se réaliser que par l'exploitation d'un langage conforme aux messages visés. Pour cela, il faut se servir d'une méthode adéquate aux circonstances de la communication. C'est ainsi que dans l'Imtâ' wa l-mu'ânasa, at-Tawhîdî procède à retranscrire les idéologies communes dans une perspective de production littéraire déterminée par le principe du discours et du récit. Faut-il voir dans cette méthode un acte de transmission destiné à l'exploration ?<br>Shared knowledge is a source of communication in the bayly life. This was particulary the case in intellectual circles in the IV/X th. Centuries, and was an essential part of life for men of letters at that time in order tout fulfil their need for discussion and establish their intellectual reputations among their acolytes. For Abû Hayyân at-Tawhîdî, overcoming the obstacle of soiocultural and religious discrimination was sufficient to reveal a free spirit, one determined to demounce evil and enshrine good. It seems his objective was educational. Ii's clear subsequently that the role of the intellectual elite is to inquire into the phenomena of life in order to serve wisdom and disseminate ethics. It is this that makes in possible to establish a perfect balance between passion and reason. Yet such a goal could only be ashieved using language that corresponded to the message. To this end, it was nacessary to to employ a method adapted to the circumstances of communication. Thus in al-Imtâ' wa l-mu'ânasa, at-Tawhîdî proceeded to retranscribe commonideologies in the course of a literary production thet was determined by the principal of discourse and narration. Should this method be viewed as an act of transmission aimed at exploration ?
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Wu, Mingfu. "A novel non-canonical WNT pathway regulates the asymmetric b cell division in Caenorhabditis elegans." Diss., Kansas State University, 2005. http://hdl.handle.net/2097/355.
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Doctor of Philosophy<br>Department of Biology<br>Michael A. Herman<br>The polarities of several cells that divide asymmetrically during C. elegans development are controlled by Wnt signaling. LIN-44/Wnt and LIN-17/Fz control the polarities of cells in the tail of developing C. elegans larvae, including the male-specific blast cell, B, which divides asymmetrically to generate a larger anterior daughter and a smaller posterior daughter. We determined that the canonical Wnt pathway components are not involved in the control of B cell polarity. However, POP-1/Tcf is involved and asymmetrically distributed to B daughter nuclei. Aspects of the B cell division are reminiscent of the divisions controlled by the planar cell polarity (PCP) pathway that has been described in both Drosophila and vertebrate systems. We identified C. elegans homologs of Wnt/PCP components and have determined that many of them appear to be involved in the regulation of B cell polarity and POP-1 asymmetric distribution to B daughter nuclei. Thus a non-canonical Wnt pathway, which is different from other Wnt pathways in C. elegans, but similar to the PCP pathways, appears to regulate B cell polarity.
Molecular mechanisms of this PCP pathway were also investigated. We determined that LIN-17/Fz is asymmetrically distributed to the B cell cortex prior to, during, and after, division. Furthermore, the asymmetric localization of LIN-17::GFP is controlled by LIN-44/Wnt and MIG-5/Dsh. The cysteine rich domain (CRD), seven trans-membrane domain and KTXXXW motif of LIN-17 are required for LIN-17 to rescue lin-17, while only seven trans-membrane domains and KTXXXW motif are required for LIN-17 asymmetric localization. MIG-5::GFP asymmetrically localized to the B cell prior to and after division in a LIN-17/Fz dependent manner. We examined the functions of these MIG-5 domains. The DEP domain is required for MIG-5 membrane association, while the PDZ domain is responsible for different levels of MIG-5 in the B daughters. The DEP and PDZ domain are required to rescue B cell polarity defect of mig-5 males, while the DIX domain is not that important. In summary, a novel PCP-like pathway, in which LIN-17 and MIG-5 are asymmetrically localized, is conserved in C. elegans and involved in the regulation of B cell polarity.
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Nakamura, Rei. "Investigation of the Role of Muller Glia-Derived Dickkopf3 (Dkk3) during Retinal Degeneration." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/310.
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Retinal degeneration is characterized by the irreversible loss of photoreceptors. A key research question is the identification and characterization of photoreceptor protective factors that prevent or delay vision loss. The Wnt pathway is a critical cellular communication pathway involved in development and diseases of the central nervous system (CNS). Recently, we discovered that multiple components of the Wnt pathway were differentially expressed in the rd1 mouse model of retinal degeneration. One of the most highly upregulated genes was Dickkopf3 (Dkk3), a secreted Wnt pathway protein of unknown function. Additionally, we demonstrated that Wnt signaling is neuroprotective in primary retinal culture (Yi et al., 2007). These data led to the hypothesis that Dkk3 is a regulator of Wnt-mediated neuroprotection during retinal degeneration. The role of Dkk3 in the retina and its activity in the Wnt pathway was identified in this dissertation project using a series of biochemical, molecular and cell biology methodologies. First, Dkk3 was shown to be expressed and secreted from Muller glia in mouse retinal tissue and primary Muller glia culture. I then demonstrated that Muller glia are a Wnt-responsive cell type and that Dkk3 potentiates Wnt3a-mediated signaling. Interestingly, the latter effect was not observed in other cell types in the retina such as retinal ganglion cells and retinal pigmented epithelial cells. Thus, Dkk3 may act on Muller glia to positively modulate Wnt signaling during retinal degeneration, which could potentially amplify the neuroprotective activity of the Wnt pathway. Next, the role of Dkk3 in cellular viability was explored. HEK293 cells stably expressing Dkk3 were shown to be significantly protected from staurosporine-induced apoptosis compared with vector control. This result suggests that Dkk3 may mediate a direct pro-survival effect onto photoreceptors during retinal degeneration. Protein interaction experiments demonstrated that Dkk3 formed a complex with the single pass transmembrane proteins Krm1 and Krm2 in the membrane, potentially in the endoplasmic reticulum (ER). Furthermore, Wnt signaling luciferase reporter assays demonstrated that Krm2, but not Krm1, abolished Dkk3-mediated Wnt3a potentiation. These data suggest that Dkk3 modulates Wnt signaling by antagonizing Dkk1-Krm dependent Wnt inhibition. Further studies will determine whether this activity is sufficient for the potentiation of Wnt signaling by Dkk3. Lastly, co-immunoprecipitation followed by mass spectrometry analysis was used to identify a novel interacting protein of Dkk3. Dkk3 was shown to interact with glucose response protein 78 (GRP78), an ER-resident chaperone. This suggested that Dkk3 protein is part of the unfolded protein response through GRP78 in the ER. In conclusion, these studies identified two novel functions of Dkk3 in regulating Wnt signaling pathway and cellular viability and suggest a physiological role for Dkk3 and Wnt signaling during retinal degeneration. Future studies will explore the significance of Dkk3-Krm and Dkk3-GRP78 interactions in the retina. Further, elucidation of the regulation of Dkk3 and other Wnt ligands in the ER and the consequence of ER stress on the biological activity of Wnt signaling will provide a better understanding of the role of the Wnt pathway during retinal degeneration.
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Ataman, Bulent. "The Molecular Mechanisms of Activity-Dependent Wingless (Wg)/Wnt Signaling at a Drosophila Glutamatergic Synapse: a Dissertation." eScholarship@UMMS, 2008. https://escholarship.umassmed.edu/gsbs_diss/353.
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Synaptic plasticity, the ability of synapses to change in strength, underlies complex brain functions such as learning and memory, yet little is known about the precise molecular mechanisms and downstream signaling pathways involved. The major goal of my doctoral thesis was to understand these molecular mechanisms and cellular processes underlying synaptic plasticity using the Drosophilalarval neuromuscular junction (NMJ) as a model system.
My work centered on a signaling pathway, the Wg/Wnt signaling pathway, which was found to be crucial for activity-driven synapse formation. The Wg/Wnt family of secreted proteins, besides its well-characterized roles in embryonic patterning, cell growth and cancer, is beginning to be recognized as a pivotal player during synaptic differentiation and plasticity in the brain. At the DrosophilaNMJ, the Wnt-1 homolog Wingless (Wg) is secreted from presynaptic terminals and binds to Frizzled-2 (DFz2) receptors in the postsynaptic muscle. Perturbations in Wg signaling lead to poorly differentiated NMJs, containing synaptic sites that lack both neurotransmitter release sites and postsynaptic structures. In collaboration with other members of the Budnik lab, I set out to unravel the mechanisms by which Wg regulates synapse differentiation. We identified a novel transduction pathway that provides communication between the postsynaptic membrane and the nucleus, and which is responsible for proper synapse development. In this novel Frizzled Nuclear Import (FNI) pathway, the DFz2 receptor is internalized and transported towards the nucleus. The C-terminus of DFz2 is subsequently cleaved and imported into the postsynaptic nucleus for potential transcriptional regulation of synapse development (Mathews, Ataman, et al. Science (2005) 310:1344).
My studies also centered on the genetic analysis of Glutamate Receptor (GluR) Interacting Protein (dGRIP), which in mammals has been suggested to regulate the localization of GluRs and more recently, synapse development. I generated mutations in the gene, transgenic strains carrying a dGRIP-RNAi and fluorescently tagged dGRIP, and antibodies against the protein. Remarkably, I found dgrip mutants had synaptic phenotypes that closely resembled those in mutations altering the FNI pathway. Through the genetic analysis of dgrip and components of the FNI pathway, immunoprecipitation studies, electron microscopy, in vivotrafficking assays, time-lapse imaging, and yeast two-hybrid assays, I demonstrated that dGRIP had a hitherto unknown role as an essential component of the FNI pathway. dGRIP was found in trafficking vesicles that contain internalized DFz2. Further, DFz2 and dGRIP likely interact directly. Through the use of pulse chase experiments I found that dGRIP is required for the transport of DFz2 from the synapse to the nucleus. These studies thus provided a molecular mechanism by which the Wnt receptor, DFz2, is trafficked from the postsynaptic membrane to the nucleus during synapse development and implicated dGRIP as an essential component of the FNI pathway (Ataman et al. PNAS (2006) 103:7841).
In the final part of my dissertation, I concentrated on understanding the mechanisms by which neuronal activity regulates synapse formation, and the role of the Wnt pathway in this process. I found that acute changes in patterned activity lead to rapid modifications in synaptic structure and function, resulting in the formation of undifferentiated synaptic sites and to the potentiation of spontaneous neurotransmitter release. I also found that these rapid modifications required a bidirectional Wg transduction pathway. Evoked activity induced Wg release from synaptic sites, which stimulated both the postsynaptic FNI pathway, as well as an alternative presynaptic Wg pathway involving GSK-3ß/Shaggy. I suggest that the concurrent activation of these alternative pathways by the same ligand is employed as a mechanism for the simultaneous and coordinated assembly of the pre- and postsynaptic apparatus during activity-dependent synapse remodeling (Ataman et al. Neuron (2008) in press).
In summary, my thesis work identified and characterized a previously unrecognized synaptic Wg/Wnt transduction pathway. Further, it established a mechanistic link between activity-dependent synaptic plasticity and bidirectional Wg/Wnt signaling. These findings provide novel mechanistic insight into synaptic plasticity.
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Lai, Wan Teng [Verfasser]. "We come. We work. We relate. The migrant labourers in Penang / Wan Teng Lai." Bonn : Universitäts- und Landesbibliothek Bonn, 2017. http://d-nb.info/1149050748/34.
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Welsing, Marcel [Verfasser]. "Die Vorgaben des Art. 57 WSA und die konstitutionellen Verfassungen der thüringischen Staaten / Marcel Welsing." Baden-Baden : Nomos Verlagsgesellschaft mbH & Co. KG, 2016. http://d-nb.info/1106337816/34.
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Liu, Wan-hsin [Verfasser]. "Determinants of Industrial Innovation in China and the Role of University Research / Wan-Hsin Liu." Kiel : Universitätsbibliothek Kiel, 2012. http://d-nb.info/102748865X/34.
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Henry, Julia, та Thomas Fischer. "التوعية الصحية للمراة - alhaml, alwilada wa nifass: الحمل,الولادة والنفاس - Atawiaa asihia lelmaraa". Zentrum für Forschung, Weiterbildung und Beratung (ZFWB) an der ehs Dresden gGmbH, Dresden, 2020. https://slub.qucosa.de/id/qucosa%3A75298.
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Die Broschüre ist ein Ergebnis des Projektes 'Gesundheitskompetenz für Migrantinnen und Migranten', gefördert durch das Sächsische Staatsministerium für Soziales und Gesellschaftlichen Zusammenhang. Das Projekt wurde durchgeführt durch die Zentrum für Forschung, Beratung und Weiterbildung an der Evangelischen Hochschule Dresden gGmbH. Basierend auf verschiedenen wissenschaftlichen Erhebungen wurde dabei der Edukationsbedarf im Hinblick auf Schwangerschaft, Geburt und Wochenbett bei Arabisch sprechenden geflüchteten Frauen ermittelt.
Zielgruppe der Publikation sind Multiplikatoren ('Peers') sowie Arabisch sprechende Frauen und deren Familien. Sie enthält laiengerecht aufbereitete Informationen Schwangerschaft, Geburt, Wochenbett und seelischer Gesundheit in der Schwangerschaft.
Die Broschüre ist in arabischer Sprache verfasst. Eine identische deutsche Sprachfassung liegt ebenfalls vor.
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Al-Maguz, M. A. T. "A critical edition of fourteenth part of Kitab An-Nawadir Wa Az-Ziyadat by Ibn Abi Zayd Al-Qayrawani 310 A.H. - 386 A.H." Thesis, University of Exeter, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234558.
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Kiernan, Matthew D. "Identifying and understanding factors associated with failure to complete infantry training among British Army recruits." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/11699/.
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BACKGROUND: Over 30% of the British Army‟s Infantry Recruits who underwent training between 1999 and 2003 failed to complete their training. Previous studies have focused predominantly on identifying the cumulative reasons for failure. There is a dearth of research investigating the effect of failure on the individual recruit and what influences their ability to pass training. AIM: The overall aims of this study were: to achieve an understanding of the role that antecedent personal, social and demographic factors play in a British Army recruit‟s ability to complete basic training; to investigate the possibility of identifying predictive factors that would identify infantry recruits who were at risk of being unable to cope with the transition to life in the British Army; and to explore the reasons given by those recruits who failed to complete basic training to develop a more comprehensive understanding of why recruits fail. METHODS: All new army recruits joining the first and second battalion between September 2002 and March 2003 were invited to take part in the study. A biographical questionnaire based on a modified version of the US Army‟s 115 item biographical questionnaire form was self-completed prior to infantry training by all those agreeing to take part in the study. Study participants were monitored weekly throughout their training and the training outcome (pass/fail) was recorded. The data was randomly split into a development dataset (two thirds) and a test dataset (one third). Independent variables were grouped into five categories (Demographic & Physical Measurement, Education, Outdoor Education, Non-Physical Activity and Conduct and Behaviour) and tested univariably and multivariably to examine their association with training outcome in the development dataset using logistic regression. The multivariable model was then used to construct a score and its sensitivity and specificity was tested using the test dataset. All those within the study who failed to complete Infantry recruit training were invited to take part in a qualitative semi-structured exit interview. These interviews were analysed using framework analysis methodology. Findings from both the quantitative and qualitative analysis were integrated to determine whether prediction of failure was practicable and to develop an increased understanding of the impact that antecedent factors and training experiences contributed to training failure. RESULTS: Of the study cohort of 999 recruits 36.2% (n=362) failed. Within the failure group 74.4% (n=269) gave reasons to suggest that this was attributable to difficulties in adapting to life in the British Army Infantry. Factors associated with higher odds of failure were: absence of female siblings (p=0.005), aggressive coping strategies (p=0.013), use of ecstasy (p=0.02), evenings per week spent at the family home (p=0.032), truancy (p=0.039), an increased number of schools attended (p=0.046) and classroom behaviour (p=0.052). The area under the curve on the test dataset was 0.58 (0.501-0.65 95% CI). Analysis of the qualitative data suggested that there was a marked difference between the socio-personal identity of recruits who failed training and the organisational identity of the British Army Infantry. Cognitive dissonance and varying extremes of stress were reported by those recruits that failed during the transition to military life. CONCLUSION: A screening tool constructed from items of the biographical questionnaire was unable to predict failure in training with sufficient accuracy to recommend its routine use for new recruits to British Army Infantry training. This study has identified that there is a lack of fit between military identity and the socio-personal identity of the infantry recruit which results in dissonance and stress during the transition into the military. It is recommended that future studies should focus on how to reduce the psychological impact of the transition into infantry training.
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Villetard, Gabrielle. "Traduction commentée du Kitāb Riyāḍat al-nafs wa Adab al-nafs (Du redressement de l’âme et De l’éducation de l’âme) d’al-Ḥakīm al-Tirmidhī (m. vers 300/910)". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEP039/document.
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Cette thèse propose la traduction et le commentaire de la Riyāḍa et de l’Adab al-nafs d’al-Ḥakīm al-Tirmidhī, mystique sunnite khorasanien des 9ème et 10ème siècles de l’ère commune, connu pour l’impact qu’a eu son Kitāb khatm al-awliyā’ sur la pensée postérieure, celle d’Ibn ‘Arabī (m. 638/1240) en particulier. Ce sont deux manuels fondamentaux d’anthropologie spirituelle qui témoignent d’une mystique philosophique islamique ancienne assimilant des éléments de la pensée néoplatonicienne et de traditions religieuses orientales telles que le manichéisme et le bouddhisme. La systématisation du concept de sainteté (walāya) caractérise cette pensée que l’on pourrait qualifier de théosophique : dans la Riyāḍa et l’Adab sont ainsi exposées les règles de l’éducation de l’égo en vue de rétablir l’ascendant du cœur sur ce dernier, transformant le croyant en saint (walī). L’éthique de Tirmidhī se rapproche du principe bouddhiste selon lequel des actes apparemment identiques proviennent soit d’une motivation désintéressée soit d’une motivation égoïste. Le cœur, organe cognitif et organe de l’action, produit des actes conformes à la connaissance divine, tandis que l’âme s’approprie les actes pour satisfaire sa passion égoïste. L’anthropologie du Sage de Termez possède une dimension cosmologique, caractéristique elle aussi de la théosophie mystique : le saint, libéré de l’égo, voit apparaître en son cœur l’ordre divin régissant les mondes et devient ainsi lieutenant de Dieu, l’instrument d’une manifestation divine qui établit au sein de la communauté des croyants et dans le monde l’ordre de l’unicité et de la Loi que le culte de l’égo transgresse et corrompt. Les caractéristiques du saint chez Tirmidhī – sa connaissance et son pouvoir théophaniques – possèdent des correspondances évidentes avec celles attribuées à l’imam dans le shi‘isme<br>This thesis proposes the translation of and commentary on the Riyāḍa and the Adab al-nafs of al-Ḥakīm al-Tirmidhī, a Khorasanian Sunni mystic from the 9th and 10th centuries of the Common Era, known for the impact that his Kitāb khatm al-awliyā' had on posterior thought, that of Ibn 'Arabī (638/1240) in particular. These are two fundamental textbooks of spiritual anthropology that testify to an ancient Islamic philosophical mysticism assimilating elements of Neoplatonic thought and Eastern religious traditions such as Manichaeism and Buddhism. The systematization of the concept of holiness (walāya) characterizes this thought that could be described as theosophical: in the Riyāḍa and the Adab are thus exposed the rules of the education of the ego in order to restore the ascendancy of the heart on the latter, transforming the believer into a saint (walī). Tirmidhī's ethic is similar to the Buddhist principle that seemingly identical acts come either from selfless motivation or from a selfish motivation. The heart, the cognitive organ and the organ of action, produces acts in accordance with the knowledge of the Law and divine attributes, while the soul appropriates acts to satisfy its selfish passion. The anthropology of the sage of Termez has a cosmological dimension, also characteristic of mystical theosophy: the saint, freed from the ego, sees appearing in his heart the divine order governing the worlds and thus becomes a lieutenant of God, the instrument of a divine manifestation which establishes within the community of believers and in the world the order of Oneness (tawḥīd) and Law that the cult of the ego transgresses and corrupts. The characteristics of the saint in Tirmidhī - his theophanic knowledge and power - have obvious correspondences with those attributed to the imam in Shi'ism
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Mannan, Ashraf-ul. "Elucidation of Theg gene role in spermatogenesis and characterisation of a novel spontaneous mutation named "nax" in mouse." Doctoral thesis, [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968492398.
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Mustroph, Angelika. "Die Bedeutung von Fermentation, Photosynthese und Pyrophosphat für das Überleben von Pflanzen unter Sauerstoffmangel." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2006. http://dx.doi.org/10.18452/15446.
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Sauerstoffmangel in Pflanzenzellen führt durch Hemmung der mitochondrialen Atmung zur Akkumulation von NADH und zu ATP-Mangel. Reis kann, im Gegensatz zu Weizen oder Kartoffeln, längere Sauerstoffmangel-Perioden überstehen. Ziel dieser Promotionsarbeit war es, einige Aspekte des Primär-Stoffwechsels zu untersuchen, die für das Überleben solcher Stresssituationen verantwortlich sein können, wie die Ethanol-Gärung, die Photosynthese sowie die Nutzung alternativer Energiedonoren. Die Ethanol-Gärung ermöglicht es Pflanzen, NAD zu regenerieren, und so die glycolytische ATP-Bildung aufrechtzuerhalten. Tolerante Reis-Pflanzen bildeten unter Anoxie in Dunkelheit mehr Ethanol als sensitive Weizen-Pflanzen. Dieser Unterschied war allerdings nur im Spross nachzuweisen und resultierte aus hohen Aktivitäten der Gärungsenzyme sowie aus großen Substratmengen in Reis-Blättern. Mehr als 24 h Anoxie konnten aber auch vom Reis aufgrund von Substratmangel nicht überlebt werden. Wurden Pflanzen bei Anoxie belichtet, verbesserten sich die Überlebensraten erheblich. Die Ethanol-Bildung war deutlich verringert, so dass neben der Gärung lichtabhängige Energie-liefernde Prozesse vermutet werden. Allerdings verlief die Photosynthese unter Anoxie aufgrund von CO2-Mangel nur vermindert ab. Eventuell könnte zyklischer Elektronentransport unter diesen Bedingungen zusätzliches ATP produzieren. In der Vergangenheit wurde vermutet, dass Pflanzen unter Sauerstoffmangel für Phosphorylierungsreaktionen statt ATP auch PPi nutzen könnten. In transgenen Kartoffelpflanzen, die infolge von Überexpression der E. coli-Pyrophosphatase weniger PPi enthielten als Wildtypen, wurde unter Hypoxie-Bedingungen nachgewiesen, dass PPi als alternativer Energiedonor bei der Saccharose-Spaltung eine bedeutende Rolle spielt. Dagegen konnte in transgenen Kartoffelpflanzen mit drastisch verminderter Aktivität der PPi-abhängigen Phosphofructokinase keine Beeinträchtigung der Stoffwechsel-Leistungen unter Hypoxie gezeigt werden.<br>Oxygen deficiency stress in plant cells leads through inhibition of mitochondrial respiration to an accumulation of NADH and a decrease in ATP content. Rice plants can survive oxygen deficiency better than wheat or potato plants. The aim of this PhD-work was to examine, which biochemical processes are responsible for plant tolerance against low oxygen stress. The studies were focused on the analysis of ethanolic fermentation, photosynthesis and the function of pyrophosphate (PPi) as an alternative energy source. By using ethanolic fermentation, plants can regenerate NAD and maintain ATP formation during glycolysis. Tolerant rice plants produced much higher amounts of ethanol during anoxia in darkness compared to sensitive wheat plants. The high fermentation rate mainly occurred in the shoots as a result of high activities of fermentative enzymes as well as high availability of carbohydrates. Nevertheless, rice plants could not survive more than 24 h of anoxia in the dark because of carbohydrate depletion. Illumination during anoxia extended survival of plants. Ethanolic fermentation rate was reduced during light exposure of plants, indicating that other energy-producing processes can compensate. However, it could be shown that the complete photosynthesis was slowed down during oxygen deficiency due to CO2 deficiency. It is likely that cyclic electron transport could at least partially contribute to ATP production during these conditions. In the past, it was speculated that PPi could replace ATP for phosphorylating processes during low oxygen stress. With transgenic potato plants expressing E. coli pyrophosphatase and therefore containing less PPi it was demonstrated that PPi is a significant alternative energy donor for sucrose cleavage during hypoxia. However, in transgenic potato plants with a reduction of synthesis and activity of PPi-dependent phosphofructokinase it could not be demonstrated that these plants suffer more from oxygen deficiency than the wildtype.
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Kölsch, Adrian. "Kinetische, theoretische und strukturelle Charakterisierung des Cytochrom c-Photosystem I-Komplexes." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21735.
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Photosystem I (PSI) aus dem thermophilen Cyanobakterium Thermosynechococcus elongatus ist ein transmembraner Protein-Pigment-Superkomplex der photosynthetischen Elektronentransportkette. Er wandelt die Energie des Lichts in elektrische Energie mit einer Quanteneffizienz von nahezu 100 % um. Dazu uberträgt PSI Elektronen von Plastocyanin bzw. Cytochrom c6 (Cyt c6) auf Ferredoxin. Die Struktur des PSI wurde bereits 2001 mit einer Auflösung von 2,5 Å beschrieben (Jordan et al. 2001). Es lässt sich zur Generierung von Photoströmen auf Elektrodenoberflächen assemblieren und zur Produktion von Biokraftstoffen mit Enzymen koppeln. Die elektrische Kontaktierung des PSI mit Elektrodenoberflächen kann durch Komplexierung mit dem mitochondrialem Cytochrom c aus Pferdeherz (Cyt cHH) erhöht werden. Aufgrund der Nutzbarkeit dieses Proteinkomplexes sollte geklärt werden, wie PSI und Cyt cHH wechselwirken und wie sich die Interaktion von der des nativen PSI-Cyt c6-Komplexes unterscheidet. Deshalb lag der Fokus meiner Arbeit darauf, die Bindung des Cyt c6 und seines Analogons Cyt cHH an PSI mit kinetischen, kalorimetrischen, theoretischen und strukturellen Methoden zu untersuchen. Das Cyt c6 bindet im reduzierten Zustand an PSI und verringert nach erfolgtem Elektronentransfer seine Affinität. Das Cyt cHH bindet dagegen sowohl im reduzierten als auch im oxidierten Zustand an PSI. Mit Hilfe der kinetischen Messungen habe ich Bedingungen identifiziert, unter denen PSI mit dem jeweiligen Cytochrom c einen stabilen Komplex eingeht. Mit Hilfe eines rigid-body dockings wurden potenzielle Bindungsstellen der beiden Cytochrome berechnet. Fur Cyt c6 ergab sich eine spezifische Bindungsstelle, die eine gute Übereinstimmung mit den von mir gemessenen Kinetiken sowie mit weiteren Literaturdaten zeigt. Diese Bindungsstelle korreliert mit der veröffentlichten Kostruktur des bakteriellen Reaktionszentrums mit Cyt c2 aus Rhodobacter sphaeroides. Demgegenüber sind mehrere Cyt cHH-Bindungsstellen ...<br>Photosystem I (PSI) from the thermophilic cyanobacterium Thermosynechococcus
elongatus is a membrane-bound, multipigment protein supercomplex. It converts light
to electrochemical energy with a quantum efficiency of almost 100 %. It reduces the
luminal proteins plastocyanin and cytochrome c6 (Cyt c6) to oxidize the stromal
protein Ferredoxin. The structure of PSI has been solved in 2001 at a resolution of
2,5 Å (Jordan et al. 2001). PSI can be assembled on an electrode surface to produce
photocurrents and the generated electrons can be used for the production of biofuels.
The mitochondrial cytochrome c from horse heart (Cyt cHH) binds strongly to both,
PSI and the electrode surface, and can therefore be applied to improve the electrical
coupling. Due to the practical use of the PSI-Cyt c complex, the aim of my thesis is
to characterize the interaction of PSI with Cyt c6 and the analog Cyt cHH. To this
end, the binding of both cytochromes to PSI was analyzed by kinetic, calorimetric,
theory-based and structural methods.
Cyt c6 binds to PSI while being reduced and decreases its affinity after transferring
its electron. In contrast, Cyt cHH binds to PSI in both oxidation states, reduced and
oxidized, with identical affinity. By means of kinetic measurements, I identified conditions in which PSI forms a stable complex with either of the two cytochromes. The positions of the cytochrome binding sites at PSI were calculated by a rigid-body docking.
For the calculation with Cyt c6, the majority of the potential binding sites are located
at the luminal side of PSI, close to P700. The theoretic properties of one of these binding
sites are in good agreement with my own kinetic measurements and literature data.
The position and orientation of Cyt c6 in this theoretic binding site is almost identical to the localization of Cyt c2 in cocrystals with the bacterial reaction center from
Rhodobacter sphaeroides. The potential Cyt cHH binding sites are uniformly distributed over
...
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Axmann, Ilka Maria. "The regulatory potential of marine cyanobacteria." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2007. http://dx.doi.org/10.18452/15598.
Full textAbstract:
Das Leben auf der Erde wird maßgeblich durch die Kraft der oxygenen Photosythese bestimmt, die Sonnen- in chemische Energie umwandelt. Cyanobakterien wie Prochloro- und Synechococcus zählen zu den wichtigsten primären Produzenten der Ozeane und werden zunehmend als Modelle für photosynthetische Organismen genutzt. Um die Regulationsmechanismen dieser Picocyanobakterien besser zu verstehen, wurde hier die Information von vier Genomen hochgradig verwandter aber dennoch ökologisch unterschiedlich angepasster mariner Stämme genutzt in einer Kombination aus computer-gestützten und experimentellen Untersuchungen. Sequenzsignale und RNA-kodierende Gene wurden als neuartige Regulationselemente identifiziert und entlang des phylogenetischen Gradienten verglichen. Mittels ''phylogenetic footprinting'' konnte ein minimales, konserviertes Set möglicher Transkriptionsfaktoren, deren Bindestellen und Regulons aufgedeckt werden. NtcA-, LexA- und ArsR-ähnliche Motive wurden ebenso gefunden wie neue regulatorische Elemente. Mit Hilfe von RACE Experimenten wurden einige der vorhergesagten Bindestellen Promotorregionen zugeordnet. Eine Suche nach konservierten Sekundärstrukturen detektierte mehrere nicht-kodierende RNAs, benannt Yfr für cYanobacterial Functional RNA. Eine vergleichende Analyse von Yfr7 innerhalb der cyanobakteriellen Linie ergab, dass diese RNA wahrscheinlich ein Homolog der E. coli 6S RNA ist. Zwei verschiedene Yfr7 Transkripte mit einem zirkadianen aber zeitversetzten Akkumulationsmuster lassen eine Verknüpfung ihrer Expression mit dem zirkadianen Rhythmus oder der Lichtintensität vermuten. Experimente in Synechocystis deckten einen neuartigen Regulationsmechanismus durch eine antisense RNA auf, welche die Menge der isiA mRNA kontrolliert und die Assemblierung von IsiA-Superkomplexen beeinflusst. Die funktionelle Zuordnung dieser neuen Elemente wird zu einem besseren Verständnis regulatorischer Netzwerke in marinen Cyanobakterien und darüber hinaus führen.<br>Life on Earth is driven by the power of oxygenic photosynthesis transforming solar into chemical energy. Cyanobacteria such as Prochlorococcus and Synechococcus belong to the most important primary producers within the oceans and increasingly serve as models for photosynthetic organisms. To better understand the regulatory mechanisms in these picocyanobacteria, here the information from four genomes of closely related and even so ecologically divergent marine strains was used in a combined computational and experimental approach. Sequence signals and RNA-coding genes as novel elements in the regulation of gene expression were identified and their distribution along the phylogenetic gradient compared. Phylogenetic footprinting revealed a minimal conserved set of putative transcription factors, their binding sites and regulons. Sites for NtcA, LexA and ArsR-like regulators were found as well as new cis elements. RACE experiments verified several of these predicted sites belonging to the promoter region. A search, focussing on conserved secondary structures, detected several non-coding RNAs named Yfr for cYanobacterial Functional RNA. A comparative analysis of Yfr7 structures, transcript types and accumulation throughout the cyanobacterial radiation indicated this RNA as the likely homologue of the E. coli 6S RNA. Two distinct Yfr7 transcripts with a circadian but time-shifted expression pattern suggested a coupling of their expression to the circadian rhythm or light intensity. Experiments in Synechocystis discovered a novel antisense RNA-mediated regulatory mechanism that controls isiA mRNA abundance and assembly of IsiA-photosystem I supercomplexes. Functional assignments of these new elements in the future will contribute to a deeper understanding of the regulatory network of marine cyanobacteria and promote new studies on bacterial ncRNAs.
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Pieper, Jörg. "Anwendung der hochauflösenden Laserspektroskopie zur Untersuchung der Energieniveaustruktur und der Elektron - Phonon - Wechselwirkung im lichtsammelnden Komplex II grüner Pflanzen." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2000. http://dx.doi.org/10.18452/14547.
Full textAbstract:
Hole-Burning (HB) und Fluorescence Line-Narrowing (FLN) bei 4.2 K sowie Experimente zur Temperaturabhängigkeit werden angewendet, um Energieniveaustruktur und Elektron-Phonon- Wechselwirkung im Antennenkomplex LHC II grüner Pflanzen zu untersuchen. Besondere Aufmerksamkeit gilt dabei der Vermeidung systematischer Meßfehler durch Reabsorption von Fluoreszenz oder durch Lichtstreuung und unerwünschtes Lochbrennen bei FLN-Experimenten. Durch die Auswertung von Lochspektren können erstmals drei niederenergetische elektronische Zustände bei 677.1, 678.4 und 679.8 nm nachgewiesen werden. Die inhomogene Breite der zugehörigen Absorptionsbanden beträgt etwa 4 nm. Wahrscheinlich stellt jeder dieser Zustände das tiefste Energieniveau einer Untereinheit des LHC II-Trimers dar und ist weitgehend an jeweils einem Chl a-Molekül lokalisiert. Die energetische Differenz zwischen den drei Zuständen kann durch strukturelle Heterogenität erklärt werden. Es kann nachgewiesen werden, daß die Meßergebnisse praktisch frei von Effekten durch unerwünschte Aggregation sind. Die homogene Linienbreite des energetisch tiefsten Zustandes bei 4.7 K wird vorwiegend durch phasenzerstörende Prozesse (pure dephasing) bestimmt. Die Lochbreiten innerhalb der 650 nm Absorptionsbande entsprechen Chl b-Chl a Energietransferzeiten von 1 ps und etwa 240 fs bei 4.2 K, während Lochbreiten innerhalb der 676 nm Absorptionsbande Chl a-Chl a Energietransferzeiten in der Größenordnung von 6-10 ps ergeben. In einer theoretischen Betrachtung werden die Beiträge zu Phonon-Seitenbanden bei HB und FLN separat analysiert. Auf dieser Grundlage können Ergebnisse von HB und FLN Experimenten an LHC II erstmals in einem konsistenten Modell durch schwache Elektron-Phonon-Wechselwirkung mit einem Huang-Rhys-Faktor von 0.9 und ein breites, stark asymmetrisches Ein-Phonon-Profil erklärt werden.<br>Spectral hole-burning (HB) is combined with fluorescence line-narrowing (FLN) experiments at 4.2 K and studies of temperature-dependent fluorescence spectra in order to investigate low-energy level structure as well as electron-phonon coupling of the LHC II antenna complex of green plants. Special attention has been paid to eliminate effects owing to reabsorption of fluorescence and to assure that the FLN spectra are virtually unaffected by hole-burning or scattering artifacts. For the first time, analysis of the 4.2 K hole spectra reveals three low-energy electronic states at 677.1, 678.4 and 679.8 nm, respectively. The inhomogeneous width of their absorption bands is approximately 4 nm. It is likely that each of these states is associated with the lowest energy state of one trimer subunit with the energetic separations being due to structural heterogeneity. It is likely that each of the low-energy states is highly localized on a single Chl a molecule of the corresponding trimer subunit. The results are shown to be virtually free from aggregation effects. The homogeneous width for the lowest state at 4.7 K is predominantly due to pure dephasing. Widths of holes burned into the 650 nm absorption band correspond to Chl b-Chl a energy transfer times of 1 ps and about 240 fs at 4.2 K while holewidths for the 676 nm absorption band lead to Chl a-Chl a energy transfer times in the 6-10 ps range. The complexities associated with the interpretation of the phonon structure in HB and FLN spectra are discussed by theoretically analyzing the different phonon sideband contributions. On this basis, 4.2 K HB and FLN data can be consistently interpreted for the first time by weak electron-phonon coupling with a Huang-Rhys factor of about 0.9 to protein phonons with a broad and strongly asymmetric one- phonon profile.
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Al-bsherawy, Ammar. "La réception du contrat de crédit-bail par le droit positif irakien. Étude à partir des droits français et américain." Thesis, Lyon 3, 2014. http://www.theses.fr/2013LYO30077.
Full textAbstract:
La réception du contrat de crédit-bail par le droit positif irakien n’a pas besoin d’une acculturation qui prendrait la forme de la soumission ou de l’assimilation aux règles juridiques ayant été élaborées dans un environnement juridique différent. Afin d’être accueilli par le droit positif irakien, le contrat de crédit-bail doit passer par la réception des modèles français, américain, islamique dans le système juridique irakien pour y former un droit mixte d’application spéciale. Pour fournir une explication bien satisfaisante pour la réception d’un modèle du contrat de crédit-bail dans l’ordre juridique irakien, il est indispensable de chercher des propositions plus spécifiques s’agissant la sélection des normes juridiques ; l’ajustement entre les normes empruntées et le système juridique dans lequel ils doivent être reçus ; et les relations entre les deux cultures juridiques. Le législateur irakien ne peut se limiter à une simple copie, car il doit veiller à établir des lois qui sont le reflet de la mentalité et de la culture juridique irakienne. Il est donc indispensable d’explorer plus à fond les forces qui motivent la réception du contrat de crédit-bail par le droit positif irakien : la recherche d’un système juridique, culture juridique, et culture fiscale adéquate. Cette analyse ouvre des perspectives nouvelles et soulève toute une série de questions, étudiées à la lumière des droits français, américain et irakien. Les points soulevés par la première partie de notre thèse montrent bien les stratégies, les démarches et les principaux obstacles de la transplantation indirecte des normes juridiques ayant été élaborées dans un environnement non islamique. C’est donc à l’analyse de la réception indirecte des normes juridiques applicables au contrat de crédit-bail que la première partie de la thèse est consacrée. À côté de la réception indirecte des normes juridiques applicables du contrat de crédit-bail, une transplantation directe des normes comptables et fiscales est indispensable pour la réception du contrat de crédit-bail par le droit positif irakien. L’enjeu de la réception d’un point de vue comptable et fiscal sera dès lors multiple : d’une part, un rapprochement entre le droit comptable, fiscal français et le droit fiscal, comptable irakien est souhaitable et recherché. D’autre part, un rapprochement entre le droit comptable, fiscal américain, ayant été inspiré par les normes comptables et fiscales internationales, et le droit fiscal, comptable irakien est faisable. C’est la compatibilité et l’harmonisation qui sont recherchées. C’est donc à l’analyse de la réception directe des normes comptables et fiscales applicables au contrat de crédit-bail que la deuxième partie de la thèse est consacrée<br>The receipt of the contract of finance lease in Iraqi positive law does not need an acculturation which would take the shape of submission or the assimilation to the legal rules having been elaborate in a different legal environment. To be integrated into Iraqi substantive law, the contract of finance lease must pass through the transplantation of French, American and Islamic models in the Iraqi legal system to form mixed law of special enforcement. To provide a satisfactory explanation for the adoption of a model of the contract of finance lease in the Iraqi legal system, it is essential to go beyond the often articulated approaches to legal changes. Seeking more specific proposals regarding the selection of legal innovation sources; the fit between the rules borrowed and the system in which they must be received, and the relationships between sectors of the two legal systems. The Iraqi legislator can not be limited a simple copy, because it must be sure to establish laws that are a reflection of the mentality and the Iraqi legal culture. It is therefore essential to further explore the forces that motivate the receipt of finance lease and defines its scope: the search for a legal system, legal culture, tax culture that is perceived as authentic or adequate. This analysis opens up new perspectives and raises a series of questions examined in the light of French, American and Iraqi rights. The points raised by the first part of this thesis show of strategies, approaches and the main obstacles of indirect legal transplantation of rules that have been developed in a non-Islamic environment. So the analysis of indirect receipt legal standards applicable to the contract of finance lease that the first part of the thesis is devoted. Next to the indirect receipt legal rules applicable of the contract of finance lease, a direct transplantation of accounting and tax standards is essential to receipt of contract finance lease the Iraqi positive law. The issue of receipt of an accounting and tax perspective will therefore be multiplied: One hand, reconciliation between the French accounting law, French tax law and, Iraqi accounting law, Iraqi tax law is desirable and sought after. In addition, reconciliation between the U. S. accounting law, U.S. tax law, having been inspired by the international accounting, and tax standards and Iraqi accounting law, Iraqi tax law is feasible. It is then compatibility and harmonization are sought. So the analysis of the direct receipt of accounting and tax rules applicable to the contract of finance lease that the second part of the thesis is devoted
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Jedrusik-Bode, Monika. "Molekulare Analyse der differentiellen Funktionen von Linkerhiston-Isoformen bei Caenorhabditis elegans." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964334933.
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Mathes, Tilo. "Photochemie und Signaltransduktion von Blaulichtrezeptorproteinen aus photosynthetisierenden Mikroorganismen." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15692.
Full textAbstract:
Die lichtaktivierte Kinase Phototropin aus Chlamydomonas reinhardtii, die photoaktivierte Adenylatcyclase (PAC) aus Euglena gracilis und das BLUF-Protein Slr1694 aus Synechocystis sp. PCC 6803 wurden in Hinblick auf die molekularen Details der primären photochemischen Prozesse sowie der Signalweiterleitung untersucht. Phototropin wurde mit Hilfe von Arginin aus Escherichia coli in Milligramm Mengen isoliert. Ohne Arginin wurde E. coli cAMP Rezeptorprotein assoziiert aufgefunden, welches eine hohe Homologie zu einer cAMP aktivierten Kinase aus C. reinhardtii besitzt. Volllängen Phototropin bildet wie einzelne LOV-Domänenkonstrukte ohne Kinasedomäne den Flavin-Triplettzustand und das kovalente Cysteinyl-Addukt. Der Zerfall des Signalzustandes ist in Anwesenheit von ATP beschleunigt und deutet auf Photorezeptor-Kinase Interaktion hin. Strukturelle Änderungen in der Kinasedomäne wurden durch FTIR-Differenzspektroskopie gezeigt. Über ELDOR-Spektroskopie wurde der Abstand der Photorezeptordomänen auf etwa 25 Angstrom bestimmt. Mutationen in Slr1694 an S28, N31 und W91 zeigten keine konservierten Einfluss auf die Dynamik des Signalzustands. Die Entfernung der Seitenkette von S28 führte zu einer 15 nm Rotverschiebung des Absorptionsspektrums aufgrund veränderter Wasserstoffbrückenkoordination des Kofaktors. Die Einführung von positiv geladenen Seitenketten an Stelle von N31 erhöhte die Kofaktorbindung von phosphorylierten Flavinen. Künstliche Kofaktoren wie Roseoflavin konnten in Slr1694 durch Koexpression eines prokaryotischen Flavintransporters erreicht werden. Die Rolle von M152 in PAC für die Signalweiterleitung wurde anhand der lichtaktivierten cAMP Synthese-Aktivität gezeigt. Durch ultraschnelle IR-Spektroskopie wurde die Beteiligung der Seitenketten von Y8 sowie Q50 bestätigt und eine genauere Beschreibung der Wasserstoffbrücken im langlebigen Signalzustand ermöglicht.<br>The light activated kinase Phototropin from Chlamydomonas reinhardtii, the photoactivated adenylylcyclase (PAC) from Euglena gracilis and the BLUF protein Slr1694 from Synechocystis sp. PCC 6803 were investigated concerning the molecular details of the primary photochemistry as well as signal transduction. Phototropin was isolated from Escherichia coli in mg amounts after solubilization with arginine. Without arginine E. coli cAMP receptor protein, which shows high homology to a cAMP activated kinase from C. reinhardtii, was copurified. Full length Phototropin shows similar photochemistry to LOV-domain containing proteins without the kinase including triplet and covalent cysteinyl adduct formation. Signaling state decay is accelerated in the presence of ATP and suggests photoreceptor-kinase interaction. FTIR spectroscopy showed light induced structural changes in the kinase domain. The distance of the photoreceptor domains of 25 Angstrom was determined by ELDOR spectroscopy. Mutation of the side chains of S28, N31 and W91 in Slr1694 showed no conserved influence on the dynamic of the signaling state. Removal of the hydroxyl group of S28 lead to a 15 nm red shift of the absorption spectrum as a result of altered hydrogen bond coordination of the cofactor. Introduction of positively charged side chains at the position of N31 strengthened the binding of phosphorylated flavins. An artificial flavin like roseoflavin was introduced in Slr1694 by coexpression of a bacterial flavin transporter. The essential role of M152 in PAC for signal transduction was shown by determination of light activated cAMP synthesis activity. Ultrafast IR spectroscopy confirmed the contribution of Y8 and Q50 in the photocycle and gave a more detailed description of the hydrogen bonding situation in the signaling state.
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De, Antoni Anna. "Structural and functional analysis of yeast proteins involved in ER-to-Golgi transport Sec24p family proteins and the GTPase activating protein Gyp5p /." Doctoral thesis, [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962093610.
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Köhler, Lars. "Die Bedeutung der Epiphyten im ökosystemaren Wasser- und Nährstoffumsatz verschiedener Altersstadien eines Bergregenwaldes in Costa Rica." Doctoral thesis, 2002. http://hdl.handle.net/11858/00-1735-0000-0006-AC03-E.
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Nöske, Nicole. "Effekte anthropogener Störung auf die Diversität kryptogamischer Epiphyten (Flechten, Moose) in einem Bergregenwald in Südecuador." Doctoral thesis, 2005. http://hdl.handle.net/11858/00-1735-0000-0006-B6EF-B.
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Holz, Ingo. "Diversity and Ecology of Bryophytes and Macrolichens in Primary and Secondary Montane Quercus Forests, Cordillera de Talamanca, Costa Rica." Doctoral thesis, 2003. http://hdl.handle.net/11858/00-1735-0000-0006-B682-0.
Full textAbstract:
Folgende Themenkomplexe wurden behandelt:
Biogeographie, Pflanzendiversität, Verbreitungsmuster
von Lebensformen und Arten in Mikrohabitaten sowie
entlang ökologischer Gradienten,
Epiphyt-Porophyt-Beziehungen, Vergesellschaftung,
Sekundärsukzession und die Auswahl von Indikatorarten.
Zum ersten Mal wird bei einer derartigen Untersuchung
die sekundäre Sukzession von Kryptogamengesellschaften
in tropischen Bergregenwäldern voll berücksichtigt. Die
Untersuchung wurde im Einzugsgebiet des Río Savegre auf
der pazifikseitigen Abdachung der westlichen Cordillera
de Talamanca (Costa Rica) durchgeführt.Kapitel 1 gibt eine generelle Einführung in
Tropische Bergregenwälder und die Bedeutung von Moosen
und Makroflechten als wichtige Komponenten dieser
Ökosysteme. Der Leser wird in das Untersuchungsgebiet,
sein Klima, seine Geologie und seine Vegetation
eingeführt.Im Kapitel 2 werden die pflanzengeographischen
Muster der Moose montaner Eichenwälder der Cordillera
de Talamanca dargestellt und diskutiert.Kapitel 3 diskutiert Diversität,
Mikrohabitatdifferenzierung und Lebensformenspektren
der Moose in einem hochmontanen Eichenwald Costa Ricas.
Es wurde versucht, die Moosflora aller Mikrohabitate
eines Eichenwaldes, inklusive der Strauch- und
Bodenschicht zu erfassen. Kapitel 4 und 5 beinhalten
die Beschreibung epiphytischer
Kryptogamengesellschaften (Moose und Makroflechten) in
Primär- und Sekundärwäldern. Mit Hilfe einer aus dem
Alpinismus abgeleiteten Klettertechnik wurden Bäume von
der Stammbasis bis in die Zweige der äußeren Krone
beprobt. Die Vegetationsaufnahmen repräsentieren die
Variation der epiphytischen Vegetation. Prozentuale
Deckungsgrade der rindenbewohnenden Moose und
Makroflechten wurden geschätzt und mit Hilfe einer
Detrended Correspondence Analysis (DCA)' und
nicht-metrischer Multi-response Permutation Procedure
(MRPP)' verglichen. Rindenproben der untersuchten Bäume
wurden mit deionisiertem Wasser extrahiert und der
pH-Wert bestimmt.Kapitel 4 behandelt die epiphytischen
Kryptogamengemeinschaften auf den dominierenden
Baumarten (Quercus copeyensis und Q. costaricensis)
primärer, hochmontaner Eichenwälder Costa Ricas.
Kapitel 5 vergleicht Artenreichtum, Vergesellschaftung
und Ökologie der epiphytischen Kryptogamen in primären
und sekundären hochmontanen Eichenwäldern Costa Ricas.
Quercus copeyensis-Bäume der oberen Baumschicht von
Primär- und Sekundärwäldern wurden beprobt mit dem Ziel
einen Einblick in Regenerationspotential, -muster und
-prozesse der Epiphytensukzession nach anthropogener
Störung zu erhalten.
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Laziyan, Mahemuti. "Identification and characterization of the transcriptional targets of the WNT/β-catenin signaling pathway in granulosa cells". Thèse, 2009. http://hdl.handle.net/1866/3250.
Full textAbstract:
Les Wnts représentent une famille de glycoprotéines de signalisation qui sont connues pour les nombreux rôles qu'ils jouent durant le développement embryonnaire et dans la cancerogénèse. Plusieurs Wnts, leurs récepteurs (Fzd) et d'autres composants des voies de signalisation des Wnt sont exprimés dans l’ovaire postnatal, et il a été démontré que l’expression de certains de ces gènes est régulée pendant le développement et l'ovulation/luteinization folliculaires. Toutefois, leurs rôles physiologiques dans l’ovaire demeurent mal définis. Pour étudier le rôle de WNT4 dans le développement folliculaire, nous avons entrepris d’identifier ses cibles transcriptionnels dans les cellules de la granulosa. Pour ce faire, nous avons employé la souris Catnbflox(ex3)/flox(ex3), chez laquelle une activation constitutive de la voie de Wnt/β-catenin a lieu suite à l’action de la recombinare Cre. Des cellules de la granulosa de ces souris ont été mises en culture et infectées avec un adenovirus pour causer la surexpression de WNT4 ou l’expression de Cre. L’ARN a alors été extrait de ces cellules et analysé par micro-puce. Les résultats ont démontré qu’une forte proportion des gènes induits par WNT4 étaient des gènes impliqués dans la réponse cellulaire au stress. Presque tous gènes induits par WNT4 ont également été induits par Cre, indiquant que WNT4 signale via la voie Wnt/β-catenin dans ces cellules. Nos résultats suggèrent donc que WNT4 favorise la survie des follicules par l’induction de gènes de réponse au stress dans les cellules de la granulosa, augmentant ainsi la résistance cellulaire à l'apoptose.<br>The Wnts comprise a large family of local-acting, secreted glycoprotein signaling molecules that are known mostly for the numerous roles they play in embryonic development and cancer. Several Wnts, their cognate receptors of the Frizzled (Fzd) family and other components of the Wnt signaling pathways are expressed in the postnatal ovary, and several have been shown to exhibit specific patterns of regulation in response to gonadotropin stimulation. Nonetheless, their role(s) in ovarian physiology remain poorly defined. To study the role of WNT4 in follicle development, we endeavoured to identify its transcriptional targets in granulosa cells. To this end, we used the Catnbflox(ex3)/flox(ex3) mouse model, in which constitutive activation of the Wnt/β-catenin pathway is obtained following Cre-mediated genetic recombination. Cultured granulosa cells from these mice were infected with adenoviruses to either overexpress WNT4 or to express Cre. RNA from these cells was then extracted and subjected to microarray analysis. Results revealed that a large proportion of the genes induced by WNT4 were genes previously shown to mediate cellular stress responses. Nearly all genes that were up-regulated by WNT4 were also induced by the Cre, indicating that WNT4 signals via the Wnt/β-catenin pathway in these cells. Our findings suggest that WNT4 mediates ovarian follicle survival by inducing a stress response in granulosa cells, thereby increasing their resistance to apoptosis.
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Chan, Chih-Chiang. "Feedback Regulation of Wnt Signaling by Naked Cuticle (Nkd) during Drosophila Embryogenesis." 2008. http://www4.utsouthwestern.edu/library/ETD/etdDetails.cfm?etdID=358.
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Wan, Hussin Daniel [Verfasser]. "Bayessche Betrachtung von erweiterten GARCH-Modellen / vorgelegt von D. Wan Hussin." 2010. http://d-nb.info/1003587410/34.
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Kwack, No-Wan [Verfasser]. "Zur Fundierung der monetären Krisentheorie : Marxsche epistemologische Ambivalenzen der Finanzkrisentheorie ; ein Versuch der Weiterentwicklung / vorgelegt von No-Wan Kwack." 2005. http://d-nb.info/980832934/34.
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Wan, Yee-Tak [Verfasser]. "Student expectations in the new millennium : an explorative study of the higher education in Hong Kong / vorgelegt von Yee-Tak Wan." 2006. http://d-nb.info/981077056/34.
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Kim, Suk-Wan [Verfasser]. "Die Bildung des Körpers : eine Untersuchung zu der gesellschaftlichen und kulturellen Formung des Körpers von der Antike bis zur frühen Neuzeit / vorgelegt von Suk-Wan Kim." 2006. http://d-nb.info/990672964/34.
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Damianitsch, Katharina. "Die Funktion des Wnt Antagonisten XsFRP5 während der frühembryonalen Musterbildung des Entoderms in Xenopus laevis." Doctoral thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-000D-F157-1.
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Weland, Nadine. "Diversity and trophic structure of the soil fauna and its influence on litter decomposition in deciduous forests with increasing tree species diversity." Doctoral thesis, 2009. http://hdl.handle.net/11858/00-1735-0000-0006-B679-6.
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Chuang, Eugenia Han-Ning. "Effects of Wnt and different TLR stimulations on microglia-induced invasion of breast cancer cells." Doctoral thesis, 2011. http://hdl.handle.net/11858/00-1735-0000-000D-F01F-7.
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Hsiao, He-Hsuan. "Mass Spectrometric Analyses of Post-Translationally Modified Proteins." Doctoral thesis, 2010. http://hdl.handle.net/11858/00-1735-0000-0006-ADDD-D.
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Floerl, Saskia. "Identifizierung und Charakterisierung extrazellulärer Proteine unter dem Einfluss von Verticillium longisporum in Arabidopsis thaliana und Raps (Brassica napus)." Doctoral thesis, 2007. http://hdl.handle.net/11858/00-1735-0000-000D-F12A-5.
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Cooper, Benjamin. "Membranglykoprotein M6a: Expression und Regulation im Gehirn unter Stress." Doctoral thesis, 2007. http://hdl.handle.net/11858/00-1735-0000-000D-F13E-A.
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Hauer, Florian. "Three-dimensional electron microscopy of structurally heterogeneous biological macromolecules." Doctoral thesis, 2009. http://hdl.handle.net/11858/00-1735-0000-0006-B504-1.
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Petersen, Ute. "Effects of agricultural management and manipulated plant species composition of permanent grassland on productivity and sward structure." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-EF38-3.
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Hofman-Hüther, Hana. "Wirkung schwerer Ionen auf strahlenresistente und strahlensensitive Tumorzellen." Doctoral thesis, 2001. http://hdl.handle.net/11858/00-1735-0000-0006-AE6B-3.
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Löber, Jana. "Identifizierung und funktionelle Charakterisierung neuer RNA-Transportfaktoren in der Xenopus laevis Oozyte." Doctoral thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-0006-ACF5-E.
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Kesting, Stefan. "Shrub encroachment of temperate grasslands: Effects on plant biodiversity and herbage production." Doctoral thesis, 2009. http://hdl.handle.net/11858/00-1735-0000-0006-B044-0.
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Streich, Jan-Hendrik. "Rheumatoide Arthritis: Proteomische Analyse von Serum und synovialen Fibroblasten zur Detektion von Biomarkern." Doctoral thesis, 2009. http://hdl.handle.net/11858/00-1735-0000-0006-AD60-1.
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Gouloudis, Christos. "Expression, Charakterisierung und Kristallisation der spleißosomalen Proteine SMNrp, U4/U6-60k und U4/U6-90k." Doctoral thesis, 2005. http://hdl.handle.net/11858/00-1735-0000-0006-ABAE-5.
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Mitkovski, Miso. "Veranschaulichung subzellulärer physikalischer Kräfte biochemischen und mechanischen Ursprungs mittels FRET." Doctoral thesis, 2005. http://hdl.handle.net/11858/00-1735-0000-0006-ABA6-6.
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Gerich, Florian. "Redoxmodulation Hippokampaler Neurone." Doctoral thesis, 2007. http://hdl.handle.net/11858/00-1735-0000-0006-ACDF-2.
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Lang, Imke Dorothea. "New fatty acids, oxylipins and volatiles in microalgae." Doctoral thesis, 2007. http://hdl.handle.net/11858/00-1735-0000-0006-ACE4-3.
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Chen, Tsai-Wen. "A Systems Level Analysis of Neuronal Network Function in the Olfactory Bulb: Coding, Connectivity, and Modular organization." Doctoral thesis, 2008. http://hdl.handle.net/11858/00-1735-0000-000D-F166-0.
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Grotjohann, Tim. "Generation of Novel Photochromic GFPs: Fluorescent Probes for RESOLFT-type Microscopy at Low Light Intensities." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-EF5C-2.
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Naumann, Peter-Thomas. "Versuche zur Strukturaufklärung bakterieller Thiouridin Synthetasen." Doctoral thesis, 2006. http://hdl.handle.net/11858/00-1735-0000-0006-AC64-1.
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