Refine
Has Fulltext
- no (110) (remove)
Year of publication
- 2021 (110) (remove)
Document Type
- Doctoral Thesis (110) (remove)
Is part of the Bibliography
- yes (110)
Keywords
- Alterung (2)
- Deutschland (2)
- aging (2)
- atomic force microscopy (2)
- cell wall (2)
- 13CO2 labeling (1)
- 1950er Jahre (1)
- 3D breast cell model (1)
- 3D motion analysis (1)
- 3D-Bewegungsanalyse (1)
Institute
- Historisches Institut (13)
- Institut für Ernährungswissenschaft (13)
- Institut für Biochemie und Biologie (12)
- Öffentliches Recht (9)
- Fachgruppe Politik- & Verwaltungswissenschaft (8)
- Bürgerliches Recht (7)
- Institut für Jüdische Studien und Religionswissenschaft (6)
- Institut für Chemie (5)
- Fachgruppe Betriebswirtschaftslehre (4)
- Institut für Geowissenschaften (4)
The energy required to drive photochemical reactions is derived from charge separation across the thylakoid membrane. As the consequence of difference in proton concentration between chloroplasts stroma and thylakoid lumen, a proton motive force (pmf) is generated. The pmf is composed out of the proton gradient (ΔpH) and membrane potential (ΔΨ), and together they drive the ATP synthesis. In nature, the amount of energy fueling photosynthesis varies due to frequent changes in the light intensity. Thylakoid ion transport can adapt the energy flow through a photosynthetic apparatus to the light availability by adjusting the pmf composition. Dissipation of ΔΨ reduces the charge recombination at the photosystem II, allowing for an increase in ΔpH component to trigger a feedback downregulation of photosynthesis. K+ Exchange Antiporter 3 (KEA3) driven K+/H+ antiport reduces the ΔpH fraction of pmf, thereby dampening a non-photochemical quenching (NPQ). As a result, it increases the photosynthesis efficiency during the transition to lower light intensity. This thesis aimed to find the answers for questions concerning KEA3 activity regulation and its role in plant development. Presented data shows that in plants lacking chloroplast ATP synthase assembly factor CGL160 with decreased ATP synthase activity, KEA3 has a pivotal role in photosynthesis regulation and plant growth during steady-state conditions. Lack of KEA3 in cgl160 mutant results in a strong growth impairment, as photosynthesis is limited due to increased pH-dependent NPQ and decreased electron flow through cytochrome b6f complex. Overexpression of KEA3 in cgl160 mutant increases charge recombination at photosystem II, promoting photosynthesis. Thus, during periods of low ATP synthase activity, plants benefit from KEA3 activity. The KEA3 undergoes dimerization via its regulatory C-terminus (RCT). The RCT responds to changes in light intensity as the plants expressing KEA3 without this domain show reduced photo-protective mechanism in light intensity transients. However, those plants fix more carbon during the photosynthesis induction phase as a trade-off for a long-term photoprotection, showing KEA3 regulatory role in plant development. The KEA3 RCT is facing thylakoid stroma, thus its regulation depends on light-induced changes in the stromal environment. KEA3 activity regulation overlaps with the stromal pH changes occurring during light fluctuations. The ATP and ADP has shown to have an affinity towards heterologously expressed KEA3 RCT. Such interaction causes conformational changes in RCT structure. The fold change of RCT-ligand interaction depends on the environmental pH value. With a combination of bioinformatics and in vitro approach, the ATP binding site at RCT was located. Introduction of binding site point mutation in planta KEA3 RCT resulted in antiporter activity deregulation during transition to low light. Together, the data presented in this thesis allowed us to assess more broadly a KEA3 role in photosynthesis adjustment and propose the models of KEA3 activity regulation throughout transition in light intensity.
Cellulose is the most abundant biopolymer on Earth and cell wall (CW) synthesis is one of the major carbon consumers in the plant cell. Structure and several interaction partners of plasma membrane (PM)-bound cellulose synthase (CESA) complexes, CSCs, have been studied extensively, but much less is understood about the signals that activate and translocate CESAs to the PM and how exactly cellulose synthesis is being regulated during the diel cycle. The literature describes CSC regulation possibilities through interactions with accessory proteins upon stress conditions (e.g. CC1), post-translational modifications that regulate CSC speed and their possible anchoring in the PM (e.g. with phosphorylation and S-acylation, respectively). In this thesis, 13CO2 labeling and imaging techniques were employed in the same Arabidopsis seedling growth system to elucidate how and when new carbon is incorporated into cell wall (CW) sugars and UDP-glucose, and to follow CSC behavior during the diel cycle. Additionally, an ubiquitination analysis was performed to investigate a possible mechanism to affect CSC trafficking to and/or from the PM. Carbon is being incorporated into CW glucose at a 3-fold higher rate during the light period in comparison to the night in wild-type seedlings. Furthermore, CSC density at the PM, as an indication of active cellulose synthesizing machinery, is increasing in the light and falling during the night, showing that CW biosynthesis is more active in the light. Therefore, CW synthesis might be regulated by the carbon status of the cell. This regulation is broken in the starchless pgm mutant where light and dark carbon incorporation rates into CW glucose are similar, possibly due to the high soluble sugar content in pgm during the first part of the night. Strikingly, pgm CSC abundance at the PM is constantly low during the whole diel cycle, indicating little or no cellulose synthesis, but can be restored with exogenous sucrose or a longer photoperiod. Ubiquitination was explored as a possible regulating mechanism for translocation of primary CW CSCs from the PM and several potential ubiquitination sites have been identified.. The approach in this thesis enabled to study cellulose/CW synthesis from different angles but in the same growth system, allowing direct comparison of those methodologies, which could help understand the relationship between the amount of available carbon in a plant cell and the cells capacity to synthesize cellulose/CW. Understanding which factors contribute to cellulose synthesis regulation and addressing those fundamental questions can provide essential knowledge to manage the need for increased crop production.
Bundeswehrapotheken
(2021)
„Bundeswehrapotheken" schildert die Entstehung und Entwicklung der Sanitätsmaterialversorgungseinrichtungen der Bundeswehr von ihrer Aufstellung Ende der 1950er Jahre bis in die 2000er Jahre. Anfangs im rechtlichen Sinne noch keine Apotheken, waren diese Einrichtungen damals in erster Linie auf den Kriegsfall ausgerichtet und von sehr begrenzter pharmazeutischer Leistungsfähigkeit.
Heute sind nur noch wenige große Bundeswehrapotheken verblieben, die jedoch hinsichtlich ihrer personellen, materiellen und infrastrukturellen Ausstattung und Möglichkeiten uneingeschränkt zivilen Einrichtungen vergleichbar leistungsfähig sind. Überwiegend mit militärischen Fachleuten besetzt und entsprechend ausgerüstet, können die heutigen Bundeswehrapotheken diese Leistung prinzipiell weltweit erbringen.
Gegliedert nach markanten Zeitabschnitten hat der Autor vor dem Hintergrund der jeweils geltenden politischen und militärischen Rahmenbedingungen sowie der Einsatzgrundsätze der Bundeswehr den Einfluss der jeweiligen rechtlichen, militärischen, gesellschaftlichen und fachlichen Vorgaben sowie prägender Ereignisse herausgearbeitet, eingeordnet und bewertet.
Hacker und Haecksen zählen zur Avantgarde der Computerisierung. Seit den späten 1970er-Jahren bildeten sie sich in der Bundesrepublik und in der DDR zu eigensinnigen ComputernutzerInnen mit einschlägigem Wissen heraus. Sie eigneten sich das Medium spielerisch an, schufen Kontakträume und brachten sich so aktiv in den Prozess der Computerisierung ein. Durch ihre Grenzüberschreitungen zeigten sie dabei Chancen und Risiken der Digitalisierung auf.
Julia Gül Erdogan geht der Entstehung der Hackerkulturen in Ost- und Westdeutschland nach. Sie analysiert, wie deren teils subversive Praktiken Machtgefüge in Politik, Wirtschaft und Gesellschaft herausforderten. Zugleich verdeutlicht die Arbeit Gemeinsamkeiten und Unterschiede der frühen sub- und gegenkulturellen Computernutzung in den beiden deutschen Teilstaaten.
The characterization of exoplanets applying high-resolution transmission spectroscopy ini- tiated a new era making it possible to trace atmospheric signature at high altitudes in exoplanet atmospheres and to determine atmospheric properties which enrich our under- standing of the formation and evolution of the solar system. In contrast to what is observed in our solar system, where gaseous planets orbit at wide orbits, Jupiter type exoplanets were detected in foreign stellar systems surrounding their host stars within few days, in close orbits, the so called hot- and ultra-hot Jupiters. The most well studied ones are HD209458b and HD189733b, which are the first exoplanets where absorption is detected in their atmospheres, namely from the alkali line sodium. For hot Jupiters, the resonant alkali lines are the atmospheric species with one of the strongest absorption signatures, due to their large absorption cross-section. However, al- though the alkali lines sodium and potassium were detected in low-resolution observations for various giant exoplanets, potassium was absent in different high-resolution investiga- tions in contrast to sodium. The reason for this is quite puzzling, since both alkalis have very similar physical and chemical properties (e.g. condensation and ionization proper- ties). Obtaining high-resolution transit observations of HD189733b and HD209458b, we were able to detect potassium on HD189733b (Manuscript 1), which was the first high-resolution detection of potassium on an exoplanet. The absence of potassium on HD209458b could be reasoned by depletion processes, such as condensation or photo-ionization or high-altitude clouds. In a further study (Manuscript II), we resolved the potassium line and compared this to a previously detected sodium absorption on this planet. The comparison showed, that the potassium lines are either tracing different altitudes and temperatures compared to the sodium lines, or are depleted so that the planetary Na/K- ratio is way larger than the stellar one. A comparison of the alkali lines with synthetic line profiles showed that the sodium lines were much broader than the potassium lines, probably being induced by winds. To investigate this, the effect of zonal streaming winds on the sodium lines on Jupiter-type planets is investigated in a further study (Manuscript III), showing that such winds can significantly broaden the Na- lines and that high-resolution observations can trace such winds with different properties. Furthermore, investigating the Na-line observations for different exoplanets, I showed that the Na-line broadening follows a trend with cooler planets showing stronger line broadening and so hinting on stronger winds, matching well into theoretical predictions. Each presented manuscript depends on the re- sults published within the previous manuscript, yielding a unitary study of the exoplanet HD189733b. The investigation of the potassium absorption required to account for different effects: The telluric lines removal and the effect of center-to-limb variation (see Manuscript I), the residual Rossiter-Mc-Laughlin effect (see Manuscript II) and the broadening of spectral lines on a translucent atmospheric ring by zonal jet streams (see Manuscript III). This thesis shows that high-resolution transmission spectroscopy is a powerful tool to probe sharp alkali line absorption on giant exoplanet atmospheres and to investigate on the properties and dynamics of hot Jupiter type atmospheres.
The Arctic environments constitute rich and dynamic ecosystems, dominated by microorganisms extremely well adapted to survive and function under severe conditions. A range of physiological adaptations allow the microbiota in these habitats to withstand low temperatures, low water and nutrient availability, high levels of UV radiation, etc. In addition, other adaptations of clear competitive nature are directed at not only surviving but thriving in these environments, by disrupting the metabolism of neighboring cells and affecting intermicrobial communication. Since Arctic microbes are bioindicators which amplify climate alterations in the environment, the Arctic region presents the opportunity to study local microbiota and carry out research about interesting, potentially virulent phenotypes that could be dispersed into other habitats around the globe as a consequence of accelerating climate change. In this context, exploration of Arctic habitats as well as descriptions of the microbes inhabiting them are abundant but microbial competitive strategies commonly associated with virulence and pathogens are rarely reported. In this project, environmental samples from the Arctic region were collected and microorganisms (bacteria and fungi) were isolated. The clinical relevance of these microorganisms was assessed by observing the following virulence markers: ability to grow at a range of temperatures, expression of antimicrobial resistance and production of hemolysins. The aim of this project is to determine the frequency and relevance of these characteristics in an effort to understand microbial adaptations in habitats threatened by climate change. The isolates obtained and described here were able to grow at a range of temperatures, in some cases more than 30 °C higher than their original isolation temperature. A considerable number of them consistently expressed compounds capable of lysing sheep and bovine erythrocytes on blood agar at different incubation temperatures. Ethanolic extracts of these bacteria were able to cause rapid and complete lysis of erythrocyte suspensions and might even be hemolytic when assayed on human blood. In silico analyses showed a variety of resistance elements, some of them novel, against natural and synthetic antimicrobial compounds. In vitro experiments against a number of antimicrobial compounds showed resistance phenotypes belonging to wild-type populations and some non-wild type which clearly denote human influence in the acquisition of antimicrobial resistance. The results of this project demonstrate the presence of virulence-associated factors expressed by microorganisms of natural, non-clinical environments. This study contains some of the first reports, to the best of our knowledge, of hemolytic microbes isolated from the Arctic region. In addition, it provides additional information about the presence and expression of intrinsic and acquired antimicrobial resistance in environmental isolates, contributing to the understanding of the evolution of relevant pathogenic species and opportunistic pathogens. Finally, this study highlights some of the potential risks associated with changes in the polar regions (habitat melting and destruction, ecosystem transition and re-colonization) as important indirect consequences of global warming and altered climatic conditions around the planet.
Brown adipose tissue (BAT) is responsible for non-shivering thermogenesis, thereby allowing mammals to maintain a constant body temperature in a cold environment. Thermogenic capacity of this tissue is due to a high mitochondrial density and expression of uncoupling protein 1 (UCP1), a unique brown adipocyte marker which dissipates the mitochondrial proton gradient to produce heat instead of ATP. BAT is actively involved in whole-body metabolic homeostasis and during aging there is a loss of classical brown adipose tissue with concomitantly reduced browning capacity of white adipose tissue. Therefore, an age-dependent decrease of BAT-related energy expenditure capacity may exacerbate the development of metabolic diseases, including obesity and type 2 diabetes mellitus. Given that direct effects of age-related changes of BAT-metabolic flux have yet to be unraveled, the aim of the current thesis is to investigate potential metabolic mechanisms involved in BAT-dysfunction during aging and to identify suitable metabolic candidates as functional biomarkers of BAT-aging. To this aim, integration of transcriptomic, metabolomic and proteomic data analyses of BAT from young and aged mice was performed, and a group of candidates with age-related changes was revealed. Metabolomic analysis showed age-dependent alterations of metabolic intermediates involved in energy, nucleotide and vitamin metabolism, with major alterations regarding the purine nucleotide pool. These data suggest a potential role of nucleotide intermediates in age-related BAT defects. In addition, the screening of transcriptomic and proteomic data sets from BAT of young and aged mice allowed identification of a 60-kDa lysophospholipase, also known as L-asparaginase (Aspg), whose expression declines during BAT-aging. Involvement of Aspg in brown adipocyte thermogenic function was subsequently analyzed at the molecular level using in vitro approaches and animal models. The findings revealed sensitivity of Aspg expression to β3-adrenergic activation via different metabolic cues, including cold exposure and treatment with β3-adrenergic agonist CL. To further examine ASPG function in BAT, an over-expression model of Aspg in a brown adipocyte cell line was established and showed that these cells were metabolically more active compared to controls, revealing increased expression of the main brown-adipocyte specific marker UCP1, as well as higher lipolysis rates. An in vitro loss-of-function model of Aspg was also functionally analyzed, revealing reduced brown adipogenic characteristics and an impaired lipolysis, thus confirming physiological relevance of Aspg in brown adipocyte function. Characterization of a transgenic mouse model with whole-body inactivation of the Aspg gene (Aspg-KO) allowed investigation of the role of ASPG under in vivo conditions, indicating a mild obesogenic phenotype, hypertrophic white adipocytes, impairment of the early thermogenic response upon cold-stimulation and dysfunctional insulin sensitivity. Taken together, these data show that ASPG may represent a new functional biomarker of BAT-aging that regulates thermogenesis and therefore a potential target for the treatment of age-related metabolic disease.
Simultaneously speculative and inspired by everyday experiences, this volume develops an aesthetics of metabolism that offers a new perspective on the human-environment relation, one that is processual, relational, and not dependent on conscious thought. In art installations, design prototypes, and researchcreation projects that utilize air, light, or temperature to impact subjective experience the author finds aesthetic milieus that shift our awareness to the role of different sense modalities in aesthetic experience. Metabolic and atmospheric processes allow for an aesthetics besides and beyond the usually dominant visual sense.
Participation has become an orthodoxy in the field of development, an essential element of projects and programmes. This book analyses participation in development interventions as an institutionalised expectation – a rationalized myth – and examines how organisations on different levels of government process it. At least two different objectives of participation are appropriate and legitimate for international organisations in the field: the empowerment of local beneficiaries and the achievement of programme goals. Both integrate participatory forums into the organisational logic of development interventions. Local administrations react to the institutionalised expectation with means-ends decoupling, where participatory forums are implemented superficially but de facto remain marginalised in local administrative processes and activities. The book furthermore provides a thick description of the organisationality of participation in development interventions. Participatory forums are shown to be a form of partial organisation. They establish an order in the relationship between administrations and citizens through the introduction of rules and the creation of a defined membership. At the same time, this order is found to be fragile and subject to criticism and negotiation.