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Staphylococcus aureus is a pathogenic bacterium infecting the human host. It’s multifaced adaptation to various environmental conditions is mediated by a tight regulation of the virulence factors influencing the host’s immune system. In this thesis two regulators of gene expression were analysed: (i) the global influence of the two-component system SaePQRS and (ii) the regulation of superantigen gene expression by the alternative sigma factor σB. At the outset of this thesis, single target genes induced by SaeRS were known (hla, hlb, cap5, fnbA, coa). In order to get a general idea of the Sae-regulon, the influence of SaePQRS on gene-expression was analysed in two strain backgrounds by proteomics and transcriptomics aproaches. Recapitulatory, expression of at least 18 secreted and two covalently cell-wall bound proteins was decreased following inactivation of the Sae-system. Sae-dependently expressed were, amongst others, well decribed virulence factors like the y-hemolysins HlgA, HlgB, HlgC, LukM and LukF, the innate immune system modulating proteins Efb, CHIPS and SCIN-B as well as the enterotoxin SEB. SaeR acts as an activator of its target genes. Some proteins were detected in increased amounts in the extracellular proteome of the Sae-deficient strain. However, these changes did not occur at the transcriptional level. The expression of virulence factors is determined by other global regulators. No influence of SaePQRS on the transcription of five substancial regulators, namely the Agr-system and its effector molecule RNAIII, the alternative sigma factor σB, the two-component system ArlRS and the DNA-binding protein SarA, could be shown. In the second part of this thesis the issue was broached to the regulation of gene-expression of a subgroup of virulence factors, the superantigens (SAgs) of S. aureus by SaePQRS and σB. In contrast to their well described molecule structure and function, the regulation of their gene expression was largely unknown. Six different S. aureus strains (two laboratory strains and four clinical isolates) encoding one to seven SAg-genes each, were used for analysis of a total of twelve SAgs regarding their transcription and mitogenic activity. The transcriptional units were characterized using Northern-Blotting. The expression of SAgs could be correlated to the respective growth phase. While egc-SAgs were expressed mainly at low optical densities, seb was induced during late growth phase. In contrast, the transcription of sea, seh, sek, tst and sep remained constant and growth-phase independent. The transcriptional dataset was verified using T-cell proliferation assays. The expression of seh, tst and the egc-operon was dependent on σB. A potential σB-dependent promotor could be identified preceeding seo, the first gene of the egc-operon. In contrast, the expression of seb was increased in sigB-deficient background. This might be due to indirect effects. Expression of seb required SaePQRS. Transcriptional datasets were verified by Immuno-Blotting and T-cell-proliferation assays. In conclusion, the same mutation in sigB but in different strain backgrounds could result in opposite phenotypes with respect to their mitogenic activity. Besides well characterized virulence factors, some secreted proteins with so far unknown function belong to the Sae-regulon. Given that the influence of SaePQRS was restricted to virulence factors and induced especially modulators of the innate immune system, it can be assumed, that these proteins potentially play a role in virulence of S. aureus. In the third part of this thesis, one of these potential new virulence factors, namely SACOL0908, was analysed in detail. In cooperation with the group of Prof. Stehle, Tübingen, the crystal structure was solved. The protein folding of SACOL0908 is new with only minor similarities to described protein structures. Recombinantly expressed SACOL0908 binds to granulocytes. These cells belong to the innate immune system, incorporate bacteria by phagocytosis and kill them. The receptor for SACOL0908 on the surface of granulocytes could not be identified using immunoprecipitation, antibody-blocking assays and functional assays in cooperation with the group of Prof. Peschel, Tübingen. The gene encoding SACOL0908 was deleted in two S. aureus strain backgrounds (COL and Newman). These mutants are currently in use to characterize their phenotype in mouse-infection studies.
The dissertation aims at developing means to integrate conservation and development in biosphere reserves in Madagascar. Despite a multitude of concepts such as UNESCO biosphere reserves, Integrated Conservation and Development Projects and community-based natural resource management, gaps between conservation and development remain to exist. In a qualitative case study in Mananara-Nord and Sahamalaza Iles-Radama Biosphere Reserves in Madagascar data was collected on biosphere reserve management, local use of natural resources and socio-cultural aspects that influence natural resource use. Furthermore, natural values local people associate with the forest were investigated. Analysis revealed that management capacities constitute a limiting factor in biosphere reserve management. Collaboration between management, local people and international organisations fosters the achievement of both conservation and development. However, collaboration is only possible if (i) clear rules are formulated and (ii) partners have a vision in common. Based on the theory of social capital, newly introduced and locally existent rules/institutions having an influence on the use of natural resource were categorized in bonding, linking and bridging social capital. Furthermore, the perception of natural values was classified in instrumental and non-instrumental values and assigned to ecosystem services identifying the importance of nature for human well-being. With the capabilities approach Amartya Sen defined human well-being as the achievement of those capabilities a person considers valuable. This includes aspects that assure livelihoods on the one hand and aspects that are conducive to well-being on the other, thus both being relevant for development. In the dissertation capabilities are based on both instrumental and non-instrumental natural values and consequently offer an opportunity to demonstrate and characterise the relationship between nature and human well-being. Social and natural values provide orientation for a biosphere reserve management. The category bonding social capital (social values) describes local socio-cultural aspects in communities and their importance for collaborative processes. Natural values provide the management with guiding principles to foster nature conservation and to integrate locally existent capabilities. Supporting and furthering these capabilities enables the development of new capabilities of all concerned persons. The dissertation demonstrates various possibilities to build bridges between (i) nature conservation and development, (ii) natural and social sciences, (iii) formal regulations and local socio-cultural aspects and (iv) diverse actors. Implementation of a social monitoring is recommended together with local stewards and Malagasy students to collect information about the perception of natural and social values and use them as guiding principles for biosphere reserves. Collaboration with national and international scientific institutions can foster this process.
Multiple sclerosis (MS) and stroke share a number of mechanisms of neuronal damage. In both cases the balance between neurodestruction and neuroprotection appears modulated by the function of the adaptive immune system. MS is a chronic inflammatory disease of the central nervous system (CNS), leading to permanent disability. It seems certain that an autoimmune response directed against the CNS is central to the pathogenesis of the disease. While these CNS-specific T cells are activated in MS patients, they are inactive and naive in healthy. Therefore it is believed that an activation of autoreactive T cells by cross-reactivity with pathogens occurs outside of the CNS. In consequence T cells express adhesion molecules and proteinases which enable them to cross the blood-brain barrier. In stroke, however, the blood-brain barrier is disturbed in its integrity caused by the decreased blood flow. Cells can freely migrate from the periphery into the brain. CNS autoreactive cells from the periphery can be activated within the CNS and thus contribute to further tissue damage. While the local autoimmune response remains temporary in stroked brains, it is chronically destroyed in MS. The differences between the underlying mechanisms are not understood. This thesis investigated T cell responses in Multiple Sclerosis in response to the therapeutics Mitoxantrone and IFN-b. The induction of a TH1 to TH2 cytokine response appears to be a shared mechanism of action between both therapeutic agents. Primarily the post stroke immune response was investigated. Patients developed a stroke induced immune suppression characterized by monocytic dysfunction and lymphocytopenia explaining the high frequency of post stroke infections. Moreover early post stroke predictors of subsequent infections, like the CD4+ T cell count, were identified. The T cell response of stroke patients appeared primed to proinflammation and unsuppressed after mitogen stimulation. A detailed understanding of post stroke immune alterations may offer new avenues of intervention to improve the clinical fate of stroke victims. In addition, such knowledge could also further our understanding of Multiple Sclerosis, because, while increasing the infection risk, the dampening of the immune system could have an important protective function, if it limits autoimmune brain damage triggered by the massive release of brain antigens during stroke. If these two pathways could be modulated separately it would create the opportunity to develop distinct therapeutic approaches that inhibit autoimmunity and strengthen antibacterial defenses. To further delineate these mechanisms it is crucial to investigate the role of the innate immune system as compared to the adaptive immune system in stroke induced immune suppression.
Background: Cardiovascular diseases are the leading cause of death worldwide. Subclinical alterations of the cardiovascular system, such as increased exercise blood pressure or an endothelial dysfunction confer a higher risk of manifest cardiovascular diseases and incident events. Detecting associations between circulating markers of the endocrine-metabolic system and the subclinical cardiovascular phenotypes could be useful to better understand cardiovascular disease progression and to improve risk prediction for manifest cardiovascular diseases. Methods: The associations between (a) serum thyroid-stimulating hormone and increased exercise blood pressure, (b) serum hemoglobin A1c and endothelial dysfunction as well as (c) serum insulin-like growth factor I and endothelial dysfunction were studied using cross-sectional data from around 1400 subjects aged 25 to 85 years collected during the 5-year follow-up of the population-based Study of Health in Pomerania (SHIP-1). Increased exercise blood pressure was defined as a value above the sex- and age-specific 80th percentile measured at the 100 W stage of a symptom-limited bicycle ergometry test. Endothelial dysfunction was defined as an impaired flow-mediated dilation measured as a continuous decrease or below the median of sex-specific distribution. Non-fasting blood samples were drawn from the cubital vein in the supine position. Results: The odds for increased systolic exercise blood pressure (odds ratio 1.24, 95% confidence interval 0.88; 1.76) and diastolic exercise blood pressure (odds ratio 0.98, 95% confidence interval 0.70; 1.39) as well as for exercise-induced increase of systolic and diastolic blood pressure were not significantly different between subjects with high and low serum thyroid-stimulating hormone levels within the reference range. In women without current use of antihypertensive medication, increasing serum hemoglobin A1c levels were associated with decreasing flow-mediated dilation levels (ß = -1.17, 95% confidence interval -2.03; -0.30). Such an association was not found in men. In men, logistic regression analysis revealed an odds ratio of 1.27 (95% confidence interval 1.07; 1.51) for decreased flow-mediated dilation for each decrement of serum insulin-like growth factor I standard deviation. In women, no significant association between serum insulin-like growth factor I levels and flow-mediated dilation was observed (odds ratio 0.88, 95% confidence interval 0.74; 1.05). Conclusions: Based on the presented results it is concluded that (a) serum thyroid-stimulating hormone levels are not associated with exercise blood pressure in the general population, (b) higher serum hemoglobin A1c levels in non-diabetic subjects are inversely associated with flow-mediated dilation in women without antihypertensive medication, but not in men, and (c) lower serum insulin-like growth factor I levels are associated with impaired endothelial function in men, but not in women. Therefore the metabolic marker hemoglobin A1c and the endocrine marker insulin-like growth factor I might be markers facilitating the identification of subjects at high risk of subclinical cardiovascular alterations.
Interactive Visualization for the Exploration of Aligned Biological Networks and Their Evolution
(2011)
Network Visualization is a widely used tool in biology. The biological networks, as protein-interaction-networks are important for many aspects in life. Today biologists use the comparison of networks of different species (network alignment) to understand the networks in more detail and to understand the underlying evolution. The goal of this work is to develop a visualization software that is able to visualize network alignments and also their evolution. The presented software is the first software for such visualization tasks. It uses 3D graphics and also animations for the dynamic visualization of evolution. This work consists of a review of the Related Work, a chapter about our Graph-based Approach for Interactive Visualization of Evolving Network Alignments, an explanation of the Graph Layout Algorithm and some hints for the Software System.
Decision making in everyday purchase situations requires mental processing of factors that are related to the items on display. These influencing factors – called persuasive information – can take various forms, like the price level, the design of the package or the display of certain product attributes. Despite the existence of persuasive information trying to influence our buying behavior, almost nothing is known about the underlying neural mechanisms responsible for processing this information. In this thesis functional magnetic resonance imaging was used to investigate neural activity correlated with product related persuasive information. As persuasive information organic, light and regular labeled food was chosen. The 1st experiment investigated the neural correlates of visually inspected organic and regular labeled food and the influence on willingness to pay (WTP) for the displayed items. It was hypothesized that organic compared to regular labeled food will be perceived as more rewarding which should be visible by an increased activity in the ventral striatum as a central area for reward processing and by a heightened WTP. As organic label information the national German eco emblem 'Bio-Siegel' was chosen (for stimuli details see 2.1). As there is no emblem indicating regular food, an artificially created logo was used for indicating a conventional product. 40 well- known food products (e.g. milk, bread, eggs etc.) were presented to the subjects. These products were marked with the organic emblem and the same 40 products with the regular label. We found that visual inspection of organic labeled food indeed led to an increase in neural activity in the ventral striatum and to a heightened WTP, suggesting a higher subjective value for these products. The 2nd experiment investigated the neural correlates of actually administered food stimuli labeled organic, light or regular and the influence on expected and experienced taste. For organic compared to regular labeled food we hypothesized an increase in expected and experienced taste pleasantness. Furthermore, light compared to regular labeled food should lead to a decrease in expected and perceived pleasantness and intensity ratings. During the active tasting process this should be accompanied by an increase in reward-related (e.g. organic vs. regular; regular vs. light) areas like the ventral striatum medial orbitofrontal cortex or aversion-related (e.g. regular vs. organic; light vs. regular) areas as the lateral orbitofrontal cortex (lOFC) and operculum/insula. As organic label information the national German eco emblem 'Bio-Siegel' was chosen. Light label information was issued in form of the internationally used 'Bewusst-Wählen®' ('Healthy Choice') label (for stimuli details see 2.2). However, inside the scanner the written forms 'Bio', 'Light' or 'Normal' (indicating regular food) were chosen. Subjects were randomly assigned in two groups and were either confronted with the organic or the regular label (organic group) or with the light or the regular label (light group) but otherwise identical milk drink. The results show that organic compared to regular labeling of identical food stimuli indeed led to an increase in expected and experienced taste pleasantness for organic labeled food. Light compared to regular labeling of identical food stimuli led to a decrease in expected and experienced taste pleasantness and intensity for light labeled food. Moreover, taste-related activity was found in aversion related areas like the operculum insula and the lOFC for food labeled regular compared to organic and in reward-related areas like the ventral striatum for food labeled regular compared to light. The results show that persuasive food-related information influences human cognition on the behavioral and neural level; the effects were shown during visual and gustatory evaluation of the stimuli. Taken together the results demonstrate that the same stimulus can vary dramatically in personal valuation depending on the applied information.
Phosphines are highly versatile ligands for transition metal catalysts because of wide tuning abilites of their stereoelectronic properties. Bulky and basic phosphines, to a smaller extend also π-acidic phosphites were intensively studied whereas dicoordinated trivalent phosphorus compounds were comparatively little investigated in this respect. In part this may go back to the limited stability of many P=C compounds, in the case of the stable benzazaphosphole to low stabilityof complexes with non-zero-valent transition metals. With the availability of suitable chelate complexes this problems may be overcome. Because biaryl phosphines proved particularly useful as chelate ligands this work is focused on the development of convenient syntheses of new biaryl-type N-heterocyclic or functionally aryl substituted 1,3-benzazaphosphole P,N- P,P- and P,O-chelate ligands and the characterization of their structures. The pivotal point was to find an applicable synthetic route to the title ligands. Because currently transition metal catalyzed cross-coupling reactions are a hot field in catalytic research, the initial target of my work was the investigation of the applicability of suitable biaryl coupling reactions on 1,3-benzazaphospholes. There are several types of transition metal catalyzed biaryl couplings. One reaction, which is currently in the main focus by use of non-toxic and air stable coupling partners, often allowing water as environmental friendly solvent, is the Pd-catalyzed Suzuki-Miyaura coupling of an aryl halide with an arylboronic acid. To apply the Suzuki coupling to the synthesis of biaryl-type benzazaphospholes, the synthesis of either benzazaphosphol-2-boronic acids or reactive 2-halogen-benzazaphospholes have to be performed. Because of the successful introduction of functional groups in position 2 of benzazaphospholes via lithiation and reaction with electrophiles, the 2-lithiation of suitably available N-substituted benzazaphospholes and introduction of boryl groups or halogen by reaction with boronic acid esters or with a halogenating reagent like dibromoethane appeared as a realistic route and was chosen for closer study. N-Neopentyl-benzazaphosphole was selected by its relatively easy access and N-mesityl-benzazaphosphole as a N-aryl representative. From the two principal methods developed to synthesize 1,3-benzazaphospholes, only the synthesis and reduction of o-aniline phosphonic acid esters to o-phosphinoanilines and subsequent [4+1] cyclocondensation is promising to access N-substituted 2-CH benzazaphospholes. My first investigations targeted to improve the synthesis of the benzazaphosphole precursors. The invention of a Cu- instead of the earlier used Pd-catalyzed P-C coupling allows a more economical access to anilinophosphonates which were then transformed to 2H-1,3-benzazaphospholes by the established orthoformamide cyclocondensation. Several attempts of the coupling with careful control of dryness of all reagents and solvents were made in order to obtain pure 1,3-benzazaphosphole-2-boronic acid ester and, after mild hydrolysis, to isolate 1,3-benzazaphosphole-2-boronic acid. The coupling worked with N-mesityl-1,3-benzazaphosphole 13e, but the benzazaphosphol-2-boronic acid could not be obtained in pure form because of easy B-C bond cleavage during crystallization, certainly by the two ‘OH groups. For attempts with a reverted methodology, the synthesis of a 2-bromo-substituted benzazaphosphole was studied, which should be coupled with (hetero)arylboronic acids via Suzuki-Mijaura reaction. However, the 2-bromo-benzazaphosphole also could not be obtained in pure form, and a coupling experiment with phenyl boronic acid and catalysis with ligand free Pd/C failed. Therefore, other routes to biaryl-type benzazaphospholes were envisaged. Direct C-H functionalization has emerged over the past few years as an attractive strategy to enhance molecular complexity. This holds also for π-excess-type heterocycles like indoles, benzoxazoles or purines which allow direct CH-arylation in 2-position. These reactions generally involve palladium based catalysts and in some cases rhodium catalysts. In a series of experiments the catalytic arylation, heteroarylation and later also alkylation were studied with 1,3-benzazaphospholes 13a-e as precursors. The initial studies were carried out with iodobenzene, keeping similar reaction conditions as for 2-CH arylation of indoles. Then transition metal catalysts, bases and conditions were varied. The necessity and influence of a catalyst was established by blind experiments without transition metal catalyst which led to strong decrease of the reactivity. However, the transitional metal catalyzed reactions of N-substituted-1,3-benzazaphosphole with aryl- and heteroaryl halides did not give the desired 2-aryl-substituted 1,3-benzazaphosphole biaryl ligands but revealed a novel oxidative addition at the P=C double bond. In the presence of moisture benzazaphospholine-P-oxides are formed. Further exploration of the scope of this reaction showed that it is applicable to several functionally substituted aryl halides and heteroaryl halides. As besides PdX2 (X = Cl, OAc) also Pd(0)(PPh3)4 was found active as catalyst, it can be assumed, that the reaction occurs via a Pd(0) species and oxidative addition of the aryl halide at Pd(0). Because Pd(0) will coordinate stronger to the π-acidic benzazaphosphole than Pd(II) it is assumed that in the first step small equilibrium amounts of a Pd(0)benzazaphosphole complex will be formed which undergo the oxidative addition and then react to benzazaphospholium salt and furnish back a Pd(0) complex with 1,3-benzazaphosphole ligand. The benzazaphospholium salts are highly sensitive to moisture and react with traces of water to form benzazaphospholine-P-oxides 20 and acid, neutralized by the base. A cyclic species RR’P(OH)=CHR”, where the halogen is replaced by OH, may be assumed as intermediate which undergoes a rearrangement to the more stable RR’P(=O)-CH2R” tautomer, driven by the high P=O bond energy. After various investigations of the optimum conditions for the reaction, a number of new functionally substituted P-aryl or P-heteroaryl benzazaphospholine P-oxides and 1,3-dineopentyl-benzazaphospholine-3-oxide were isolated and characterized by 1H, 31P, 13C and HRMS data and two by crystallography. The biaryl-type 2-phenyl-1,3-benzazaphosphole is known since the earliest reports of these heterocycles, synthesized by cyclocondensation of 2-phosphinoaniline with benziminoester hydrochloride or in low yield with benzaldehyde. The latter method was further developed because of the compatibility of the aldehyde group with various donor functions. 2-Phosphinoaniline (12a) and 2-phosphino-4-methylaniline (12b) were heated with pyridine-2-carboxaldehyde under varied conditions, and a crucial role of acid catalyst was observed in the investigation. The results showed that the dehydrogenating cyclocondensation, if catalyzed by a suitable type and amount of acid catalyst, works well for primary phosphinoanilines 12a,b and a variety of reactive aldehydes, including N-heterocyclic and o- or m-functionally substituted arylaldehydes. In an equimolar ratio, on heating usually hydrogen is eliminated, at least formally, to furnish the aromatically stabilized 1H-1,3-benzazaphosphole ring systems of 35 whereas in other cases reductive side reactions occur, e.g. the N-CH2R substitution to 36 in reactions with two equivalents of aldehyde. Thus the synthesis of 1,5-dimethyl-1,3-benzazaphosphole (36a) was achieved by double cyclocondensation of 12b and formaldehyde in a 1:2 molar ratio. This provides the so far shortest way to synthesize N-substituted 1,3-benzazaphospholes and suggests, that the reaction is generally applicable in reactions with two equivalents of monoaldehyde. This puts the question if N-secondary o-phosphinoanilines such as N-neopentyl-2-phosphinoaniline (12d) can be cyclocondensed with aldehydes to benzazaphospholes or if a primary amino group is required. The successful experiment shows that cyclocondensation of N-secondary o-phosphinoanilines with suitable aldehydes is possible. N-Neopentyl-2-pyrido-1,3-benzazaphosphole was obtained in high yield. An interesting extension of the above reaction are cyclocondensations with compounds bearing two aldehyde groups. Double condensation of 12b with o-phthaldialdehyde was performed. It proceeded fast and gave tetracyclic-1,3-benzazaphosphole in high yield. Based on the NMR monitored primary formation of organoammonium phosphino glycolates from amines, phosphines and glyoxylic acid, followed by conversion to phosphinoglycines, it is assumed that the reaction proceeds by initial attack of the primary phosphino group of 12b at the carbonyl carbon atom of R-CHO, polarized with the help of the acid catalyst. The resulting P-C bonded secondary phosphine, containing an α-hydroxy group, may release water after transfer of a proton to oxygen in equilibrium, followed by attack of amine. This leads to formation of the dihydro-intermediate 34, observed by NMR reaction monitoring in several cases. Possible ways are releasing of H2 during reflux, directly giving 2-substituted NH-1,3-benzazaphospholes 35, or hydrogen transfer, connected e.g. with N-substitution leading to 1,2-disubstituted 1,3-benzazaphospholes 36. The second path is observed mainly when excess or double molar quantities of aldehydes are used at the start of the reaction. The two hydrogen atoms at P and C2 are consumed during the second condensation and formation of the NCH2R group and generate the P=C double bond. Finally, cyclocondensation of o-phosphinoanilines with aldehydes has proven as a useful method for the synthesis of biaryl type benzazaphosphole ligands. After thorough investigations, N-primary and secondary phosphino anilines were found cyclisable with various heteroaryl aldehydes upon refluxing in toluene in the presence of a suitable acid catalyst, and 11 new compounds were synthesized following this procedure and characterized by 1H, 31P, 13C NMR and HRMS data. For two compounds crystal structures were also obtained. First attempts to synthesize chelate complexes with the 2-(hetero)aryl-1,3-benzazaphospholes were started. A soluble 2-(o-diphenylphosphinophenyl)-1,3-benzazaphoasphole-Cr(CO)4 chelate complex was detected by NMR spectroscopy, whereas most products of the new ligands with Rh(COD) or NiCp complexes were insoluble in usual NMR solvents and require further efforts for synthesis and full analytical and structural characterization.
Novel heterocyclic alpha-phosphinoamino acids, by structural relationship named 3-phosphaprolines, were obtained by cyclocondensation of 2-phenylphosphinoethylamines with glyoxylic, pyruvic or phenylglyoxylic acid at room temperature in diethylether. The reactions proceed via primary attack of the P-lone electron pair, as shown by the synthesis of phosphonium glycolates from tertiary phosphines and glyoxylic acid, and addition of PH at the carbonyl group. The ring closure proceeds by replacement of the hydroxy by the amino group and is kinetically controlled. NMR monitoring of the phosphaprolines in CD3OD over several days indicates changes of the diastereoisomer ratios leading to higher contents of the more stable trans-diastereoisomers. The zwitterionic compounds are soluble in part in CD3OD, DMF or DMSO, are somewhat sensitive to air in solution and may undergo hydrolysis with larger amounts of water. The structures are proved by multinuclear NMR spectra and two crystal structure analyses. Suitable phosphaprolines as well phosphonium glycolates and Ni(COD)2 allow to generate precatalysts, activated by NaH for the oligomerisation of ethylene to mainly linear products with methyl and vinyl end groups. Some additional investigations with phosphinophenolates, another type of P-C-C-O- ligands, were performed for comparison. Precatalysts prepared from 2-phosphinophenolesters and Ni(COD)2 at room temperature were characterized by multinuclear NMR but decomposed on heating to stable nickel cis-bis(P,O-chelate) complexes. Heating precatalysts generated from a phosphinophenolester or phosphinophenols and Ni(COD)2 in the presence of ethylene under pressure led to linear ethylene oligomers. These reactions are much faster than the above mentioned conversions with NaH activated P,O-Ni-catalysts. In the presence of 9-decenol with unprotected remote hydroxyl group incorporation of a small amount of isolated hydroxyoctyl side groups takes place, detected by 13C NMR spectroscopy. Finally it is stated that the development of a facile synthesis and the characterization of the properties of the phosphaprolines pave the way for derivatisation and further studies with these novel types of amino acids.
Proteolysis represents the final step in the life of a protein. It is one of the most important cellular processes assisted by chaperone systems and ensures an appropriate protein homeostasis. Protein degradation is essential for the removal of cytotoxic protein aggregates and mis-translated/mal-folded proteins, „unemployed“ and regulatory proteins to enable rapid cell adaptation to altering environmental conditions (Gottesman, 2003; Wiegert & Schumann, 2001; Parker, 1981; Stansfield et al., 1998; Drummond & Wilke, 2008; Goldberg, 1972; Gerth et al., 2008). The bacterial Clp (caseinolytic proteins) protease complexes are analogous to the eukaryotic 26S proteasome and consist of Hsp100/Clp proteins of the AAA+ superfamily and an associated barrel-like proteolytic chamber (e.g. ClpP). The Clp proteases seem to be responsible for the major protein turnover in low GC, Gram+ bacteria. The main goal of this thesis was to develop new methods and tools to investigate global proteolysis more precisely and to get a detailed understanding of protein degradation during starvation conditions and it´s regulation in low GC, Gram-positive bacteria. To analyse protein degradation under starvation conditions the well established glucose starvation model was used. In Bacillus subtilis it could be shown that approximately 200 proteins are selectively degraded in a glucose depletion induced stationary phase. Furthermore radioactive pulse-chase labelling experiments coupled with 2D-PAGE analysis revealed that mainly the ClpCP protease complex is involved in the degradation of proteins in the stationary growth phase. To investigate proteolysis in the human pathogen Staphylococcus aureus in the same way, a newly developed chemically defined medium was established suitable for radioactive pulse-chase labelling experiments under stable glucose starvation conditions. The degradation kinetics of individual 2D spots was significantly better resolved using 14C-BSA as an internal marker protein for the sample normalisation. A rather huge overlap was found within the functional protein classes that were degraded in B. subtilis and S. aureus the stationary phase. Among others, especially proteins involved in amino acid, nucleotide and cell wall biosynthesis were rapidly degraded, whereby not always the same and sometimes another enzymes from a biosynthetic chain were targeted for proteolysis. Despite the resolution power of the 2D-PAGE method, there are some drawbacks such as a limited "protein window" with regard to the molecular weight and isoelectric point, loss of low abundance proteins and a rather low reproducibility for time course experiments. Therefore a mass spectrometry based approach for the simultaneous detection of protein synthesis, accumulation and degradation was developed. This pulse-chase SILAC approach provides a very good reliability with a broad spectrum of proteins that can be analysed. Through the combination with ultracentrifugation even non-soluble and aggregated proteins could be analysed. Several hundred proteins were degraded in S. aureus during glucose starvation. Among them was the functional cluster of ribosomal proteins which is degraded in the early stationary phase. Furthermore proteins belonging to complexes were degraded with the same kinetic (e.g. NrdE, NrdF). In addition selective protein degradation took place according to functional categories (e.g., ribosomal proteins, biosynthetic, glycolytic enzymes) and not to regulatory groups (e.g. CcpA, SigB regulon).The investigation of a clpP deletion mutant in S. aureus revealed a greater susceptibility to aggregation, where the cells try to counteract with the expression of chaperones like GroEL/ES, ClpB and DnaK. The renaturation process is very ATP consuming and only takes place in energy rich phases of growth (e.g. from exponential to transient growth phase). Protein aggregation was found enhanced in the stationary phase. Furthermore, a higher GTP level compared to the wild-type probably resulted in a stronger CodY mediated repression with a rather low level of amino acids in clpP mutant cell. In addition substances like glycerol, which thermodynamically stabilise proteins in refolding processes (Maeda et al., 1996; Feng & Yan, 2008), were found in higher levels compared to the wild-type. A strong response to reactive oxygen species was detected in the clpP mutant strain, which is probably due to ROS production during the early stages of protein aggregation. Altogether, different methods were used for investigation protein degradation at a proteome-wide scale. Hundreds of degradation candidates were identified by gel-based and gel-free approaches in S. aureus wild-type cells. “Unemployed” proteins (e.g. ribosomal proteins, biosynthetic enzymes) were degraded and proteins particularly required and synthesized in glucose-starved cells such as TCA cycle enzymes were stable in the stationary phase. Investigation of the clpP mutant strain supports a proposed model for the pleiotropic phenotype and provides a deeper insight in the fine-tuned protein quality control and the important role of ClpP during starving conditions.
Northern peatlands are ecosystems with unique hydrological properties, storing about 400-500 Gt of carbon. As the production rate of organic material is higher than its decomposition, which is slowed down in the wet and cold environment, peatlands store a great amount of carbon. Carbon assimilated from the atmosphere during photosynthesis by plants is partly lost due to autotrophic and heterotrophic respiration as carbon dioxide (CO2), as methane (CH4) or/and as dissolved organic carbon. The proportion of each carbon component is strongly controlled by environmental conditions as temperature, radiation, precipitation and subsequent water table changes and active role of vegetation. With predicted changes in the global climate, changes in the influence of environmental parameters on peatland ecology are expected. Thus thorough research is essential for a better understanding of mechanisms which influence carbon cycling in peatlands. In this thesis, various components of the carbon cycle were studied at two boreal peatland sites (Ust Pojeg in Komi Republic in Russian Federation and Salmisuo in Eastern Finland) using the micrometeorological eddy covariance method. The focus was placed on the temporal changes of the controlling parameters, ranging from a few days during short snow thawing through the rest of the year. At the Salmisuo site, two measurement seasons allowed to address possible inter-annual variation. We observed that diurnal variations in methane emissions which are typically controlled by vegetation during the growing season, might appear during snow melt as a result of the influence of physical factors rather than biological factors. The diurnal pattern in methane emissions was caused by the interaction of the freeze-thaw cycle and near urface turbulence. During the night time, when surface temperatures fell below zero and caused formation of the ice layer, methane emissions were only around 0.8 mg m-2 h-1, however after the increase in temperature and melting of the ice layer they reached peak values of around 3 mg m-2 h-1. The near surface turbulence had a significant influence on methane emissions, however only after the thawing of the ice layer. The effect of changing environmental parameters over the year was further elaborated on a carbon dioxide time series from the Ust Pojeg site. The generally accepted effects of temperature on ecosystem respiration during the night are not stable throughout the year and can change rapidly during the growing season. Using moving window regression analysis I could show that the strength of the exponential relationship between ecosystem respiration and temperature is changing during the year. This was in correspondence with recent publications elaborating on sub-seasonal changes of the controlling parameters. In general, measurements from the Ust Pojeg site represent estimates of annual CO2 and CH4 fluxes with an annual carbon balance of -94.5 g C m-2 and a new contribution to the quantification of trace gases emissions from a Russian boreal peatland. The inter-annual comparison of net ecosystem exchange (NEE) measurements with previously published data on CH4 and DOC flux from the Salmisuo site showed that the NEE of CO2 is the most important component of the carbon balance at this site. However, primary production was not responsible for the inter-annual changes in NEE. Rather, the effects of water table position during the year had a strong influence on ecosystem respiration, which was probably due to the influence on soil respiration, and higher NEE was observed during the year with smaller primary production, but higher water table levels. The effects of higher precipitation and higher water table during the wet year were shown to increase CH4 flux and the export of DOC, but their effects could not compensate for changes in ecosystem respiration. In the presented thesis intra- and inter- annual changes in carbon flux components and their controls, in our case attributed mostly to hydrological conditions in combination with other environmental parameters as temperature and the role of peatland vegetation, are discussed.
In this thesis, two novel assay systems had been developed, which allow a fast and easy screening for amine transaminase activity as well as the characterization of the amino donor and acceptor specificity of a given amine transaminase. The assays overcome some limitations of previously described assays but of course have some limitations themselves. The relatively low wavelength of 245 nm, at which the production of acetophenone is detected with the spectrophotometric assay, limits the amount of protein/crude extract that can be applied, which eventually results in a decreased sensitivity at higher enzyme loads due to an increased initial absorbance. Otherwise, this assay can be used very easily for the investigation of the amino acceptor specificity and both pH and temperature dependencies of amine transaminases. The conductometric assay is – by its very nature – limited to low-conducting buffers, a neutral pH and constant temperatures. In summary, the assays complement one another very well and the complete characterization of the most important enzyme properties can be accomplished quickly. Furthermore, we developed and applied a novel in silico search strategy for the identification of (R)-selective amine transaminases in sequence databases. Structural information of probably related proteins was used for rational protein design to predict key amino acid substitutions that indicate the desired activity. We subsequently searched protein databases for proteins already carrying these mutations instead of constructing the corresponding mutants in the laboratory. This methodology exploits the fact that naturally evolved proteins have undergone selection over millions of years, which has resulted in highly optimized catalysts. Using this in silico approach, we have discovered 17 (R)-selective amine transaminases. In theory, this strategy can be applied to other enzyme classes and fold types as well and for this reason constitutes a new concept for the identification of desired enzymes. Finally, we applied the seven most promising candidates of the identified proteins to asymmetric synthesis of various optical pure amines with (R)-configuration starting from the corresponding ketones. We used a lactate dehydrogenase/glucose dehydrogenase system for the necessary shift of the thermodynamic equilibrium. For all ketones at least one enzyme was found that allowed complete conversion to the corresponding chiral amine with excellent optical purities >99% ee. Bearing in mind that until last year there was only one (R)-selective amine transaminase commercially available and two microorganisms with the corresponding activity described, the identification of numerous enzymes is a breakthrough in asymmetric synthesis of chiral amines.
Triple helix-forming oligonucleotides (TFOs) are one of the most specific DNA duplex binding agents and offer new perspectives towards oligonucleotide-mediated gene regulation and manipulation. However, the poor thermodynamic stability of DNA triplexes under physiological conditions limits a successful application in the antigene strategy. Thus, the conjugation of TFOs with small triplex-specific binding ligands is a promising approach to stabilize the formed complexes and to enhance their overall binding affinity. The present study focused on the synthesis of novel TFO conjugates with triplex-binding indolo[3,2-b]quinoline derivatives (PIQ) and on their ability to form and stabilize intermolecular triplexes through their recognition of a duplex target. During the course of the work the thermodynamics of conjugate binding and structural aspects of drug-DNA interactions have been characterized by a variety of spectroscopic and calorimetric techniques.
The present work provides new insight concerning histidine phosphorylation in proteins, which is an essential regulatory posttranslational modification. To study histidine phosphorylation, a newly developed NMR approach, the HNP experiment, is presented in this thesis. The HNP experiment provides specific experimental evidence of phosphorylated histidines in proteins. It allows for the determination of the regiochemistry of phosphohistidines on the basis of three individual peak patterns for distinguishing all three phosphohistidines i.e. 1- and 3-phosphohistidine and 1,3-diphosphohistidine. This novel NMR approach allows the investigation of histidine phosphorylation in proteins under physiological conditions without resorting to chemical shift comparisons, reference compounds, or radioactively labelled phosphate. In this thesis, histidine phosphorylation in the regulatory domains PRDI and PRDII of the Bacillus subtilis antiterminator protein GlcT was intensely studied. GlcT is a transcription factor, which regulates the phosphotransferase system (PTS) by modulating the expression level of PTS-enzymes (Enzyme I, HPr, Enzyme II) on a transcriptional level. Upon the phosphorylation of conserved histidines in PRDI and PRDII, the function of GlcT is regulated through its aggregation state. In this thesis, it is shown that histidines in both PRDs are primarily phosphorylated at their N(Epsilon-2), forming 3-phosphohistidine. In addition, we found, by newly optimized mass spectrometry conditions, that both PRDs are dominantly onefold phosphorylated. By using tandem mass spectrometry to study PRDI, we identified histidine 170, which is the second of two conserved histidines (His 111 and His 170), as the phosphorylation site. In this thesis, it is also shown through comprehensive mutational studies that both conserved histidines (His 218 and His 279) in PRDII can be individually phosphorylated. This is in good agreement with mass spectrometry results that indicated an additional twofold phosphorylation in PRDII. This can be explained as follows: an intra-domain phosphate transfer between both conserved histidines in PRDII might be involved in the phosphorylation reaction, finally leading to a mainly onefold phosphorylated PRDII at one of the two conserved histidines. This minor twofold phosphorylation has also been found in PRDI. However, the specific peak pattern in the HNP-spectra of PRDI strongly suggest that this additional phosphorylation originates from a 1,3-diphosphohistidine, most likely at histidine 170. Furthermore, for the first time the existence of 1,3-diphosphohistidine in a protein was found. We also show that the phosphorylation of PRDI can be achieved in the absence of Enzyme II which is in contrast to the literature. Shown by analytical gel filtration, the monomeric aggregation state of PRDI obtained upon Enzyme II-free phosphorylation is identical to the monomeric aggregation state which was proposed for the Enzyme II-dependent phosphorylation of GlcT. As shown in this thesis, the combined results of HNP-NMR, mass spectrometry and analytical gel filtration deepen our understanding of regulatory histidine phosphorylation in the individual PRDI and PRDII domains of the Bacillus sub- tilis GlcT. I anticipate that this approach will be applicable to study histidine phosphorylations in other phosphoproteins.
Background: Alcohol consumption accounts for a high burden of disease. The general population of West Pomerania has been characterized as a population at risk with a high prevalence of behavioural risk factors such as alcohol risk drinking. This is reflected by the high proportion of patients being admitted to general hospitals due to alcohol-attributable diseases. The aims of the present dissertation were (a) to analyze dose-response relations between volume of alcohol drinking and the risk of diseases with different alcohol-attributable fractions (AAF) in general hospital inpatients (study 1); (b) to assess motivation to change drinking behaviour and motivation to seek help for alcohol problems during their hospital stay as well as changes in motivation to change drinking behaviour, motivation to seek help and changes in daily alcohol consumption across time according to diseases with different AAFs (study 2); and (c) to investigate the association of fatty liver disease (FLD) with blood pressure and hypertension in a general population sample and to test for the specific contribution of alcohol consumption to this association (study 3). Methods: For studies 1 and 2, data from 'Early Intervention at General Hospitals', a randomized controlled trial to test the effectiveness of brief intervention for alcohol problem drinking in general hospitals, were used. Study 1 comprised data from 846 inpatients, study 2 comprised data from 294 inpatients aged 18 to 64 years with alcohol problem drinking and alcohol-attributable diseases from four general hospitals in West Pomerania. Hospital diagnoses were classified according to their AAF: (1) diseases wholly attributable to alcohol consumption by definition (AAF=1), (2) diseases partially attributable to alcohol consumption (AAF<1), and (3) diseases with no relation to alcohol consumption or where alcohol consumption has been found to be a protective factor (AAF=0). Study 3 encompassed data from the 'Study of Health in Pomerania', a general population sample of 3191 adults aged 20-79 years. FLD was defined using ultrasound in combination with increased serum alanine aminotransferase levels. Results: Analyses showed that 46.8% of the general hospital inpatients had a disease attributable to alcohol consumption. There was a dose-response relationship between volume of alcohol drinking and the risk of diseases with different AAFs. Inpatients consuming >120 g and inpatients consuming 61-120 g of pure alcohol per day revealed significantly higher odds for diseases with AAF=1 compared to inpatients consuming 31-60 g of pure alcohol per day with odds ratios (OR) of 6.3 (95% CI 3.6-11.3) and 2.9 (95% CI 1.6-5.1), respectively. Regarding diseases with AAF<1, inpatients consuming >120 g of pure alcohol per day had significantly higher odds compared to inpatients consuming 31-60 g of pure alcohol per day (OR 2.0, CI 1.2-3.4). Analyses on motivation to change drinking behaviour and on motivation to seek help at hospitalization revealed that motivation to change drinking behaviour was higher among inpatients with alcohol-attributable diseases than among inpatients without alcohol-attributable diseases (p<.001). Among inpatients with AAF=1, motivation to seek help was higher than among inpatients with AAF<1 and AAF=0 (p<.001). While motivation to change drinking behaviour remained stable within one year after hospitalization in all three AAF groups, motivation to seek help decreased in this time period. The volume of alcohol consumed decreased in all three AAF groups within one year after hospitalization. Data from the general population study revealed that FLD was associated with blood pressure and hypertension at baseline and at five-year examination follow-up. For example, the chance of hypertension at both time points was threefold higher in individuals with FLD (OR 2.8, CI 1.3-6.2; OR 3.1, CI 1.7-5.8, respectively) compared to individuals without FLD. Analyses further revealed that the association of FLD with blood pressure and hypertension was independent of alcohol consumption. Conclusion: The results of the present dissertation provide relevant implications for public health. In view of the high proportion of general hospital inpatients with alcohol-attributable diseases, a screening procedure for problem drinking is needed. Furthermore, appropriate interventions considering the inpatient’s motivational level have to be implemented. The concept of AAFs to classify disease conditions according to their causal relationship with alcohol consumption might be a tool to detect inpatients with problem drinking. The results regarding FLD and its association with blood pressure and hypertension demonstrate that it is important to pay attention to alcohol-attributable diseases in the general population and that alcohol-attributable diseases are associated with subsequent serious sequelae. The results of the present work further indicate that the concept to distinguish between alcoholic and non-alcoholic origin of FLD might be obsolete and should be replaced by a concept that regards FLD as a multifactorial disease condition.
IL-10 drives the re-establishment of peritoneal macrophage populations in bacterial peritonitis
(2011)
The aim of this thesis work was to explore the physiological and functional properties of peritoneal macrophage populations in both the steady state and in inflammatory conditions. In the steady state there are two populations of macrophages in the peritoneum which I refer to as the R1 and R2 populations. The R1 cells are a rapidly turning over population which constitute around 20% of the peritoneal macrophages. I show that these cells have the capacity to efficiently present peptides on MHC-II to CD4+ T cells but that they are poor at phagocytosis. Monocytes transferred into the un-infected peritoneum give rise almost exclusively to this R1 population, suggesting that the R1 fate is the default pathway of monocyte development under steady state conditions. In contrast, the R2 population in the peritoneum turns over very slowly in the steady state and is composed of cells which are poor at the presentation of peptide to T cells but which are efficient at phagocytosis. Both of these populations are lost from the peritoneum within an hour of the induction of a poly-microbial peritonitis. A large fraction of the R2 population relocates from the peritoneal wash fraction to the omentum, the fate of the R1 population is less clear. Over the course of the next three days, the macrophage populations in the peritoneum are re-established. Transfer experiments using genetically marked cell populations demonstrated that neither the R1 nor the R2 populations which “disappeared” one hour after infection contributes to the re-established peritoneal wash fraction macrophage pool at day 3. While the re-established R1 population retains the functional properties and the FACS phenotype of the steady state R1 cells, the re-established R2-like population is clearly not identical to the R2 cells present in the pre-infection environment. In particular, this R2-like population can be split into two sub-populations which have non-identical functional properties. In this inflammatory situation monocytes transferred into the peritoneum now acquire the capacity to differentiate not only into R1-like cells but also into R2-like macrophages. I looked for the molecular basis driving this change of monocyte differentiation in the infected peritoneum by using a solid phase cytometry based ELISA procedure to examine the spectrum of cytokines produced in the peritoneum in response to poly-microbial infection. One of the most prominent cytokines produced early in infection is IL-10. To determine whether IL-10 is directly involved in assigning monocyte fate in the peritoneum I looked at the ability of mice carrying a targeted deficiency of either the IL-10 gene or of the IL-10 receptor gene to form the R2-like cells after infection. Neither mouse strain efficiently generates the R2-like population after infection. Adoptive transfer of genetically marked wild type or mutant monocytes into appropriate hosts demonstrated that the effect of IL-10 is not direct. Rather, the IL-10 responding cell produces a mediator which then directs monocyte fate. Thus, the bystander IL-10R deficient monocytes are driven by the mediator produced by wild type monocytes to generate R2 cells with high efficiency. The crucial role of this IL-10 dependent pathway was underscored by supplementation experiments. Mice carrying a targeted deficiency of the IL-10 gene fail to generate the R2 population during peritonitis. However, injection of IL-10 into these animals rescues the capacity to form the R2 population. In addition the normal default pathway of monocyte development in un-infected animals which leads to the R1 population is modulated by injection of IL-10 so that the monocytes can now differentiate into the R2 population. The work presented in this thesis describes the steady state populations of phagocytes in the un-infected peritoneum and the dynamics of these populations during the induction of peritonitis. It also uncovers an IL-10 dependent pathway which regulates the choice of monocyte developmental fate within the peritoneum.
Recent climate change has affected the forest system comprehensively. Northern hemisphere elevational treelines are considered as a key environment for monitoring the effects of current anthropogenic climate change. Moreover, trees from these areas are also widely employed in paleo-climate reconstructions. The stability of the tree growth climate relationship under current scenario is crucial for all tree ring based climate researches. It is important to investigate how trees respond to this rapid environmental change at altitudinal treelines. Tree cores from 21 treeline sites of three species (Pinus tabulaeformis, Picea crassifolia, and Sabina przewalskii) from Northeastern Tibetan have been conducted in this thesis. The instable correlations between tree growth and climate are the general response pattern of trees from all study sites in NE Tibetan Plateau. Picea crassifolia shows the most instable response to climate factors (mean monthly temperature and total monthly precipitation). Pinus tabulaeformis and Sabina przewalskii just showed instable and divergent responses to their main limiting climate factors but no clear trend was found which is limited by the few sample sites. Corresponding to divergent responses of Picea crassifolia to mean monthly temperature, most radial growth of Picea crassifolia were inhibited by this climate change type drought, only few trees within same sites grew faster due to temperature increasing during recent decades. The divergence response mainly started in last 30 years in six of eleven sample sites over the Northeastern Tibetan Plateau. North-westerly drier sites showed a large percentage of trees per site with a negative correlation to temperature and mostly southerly moister sites showed more mixed responses with both negatively and positively responding trees within site. Concurrent with the regional pattern, low elevation sites show mostly negative correlations with temperature and high elevation sites show more mixed responses. As the hydrothermal conditions of the investigation area changed to a drier and warmer combination, drought stress on tree growth have been intensifying over time and expanding spatially from the middle to most of our study area during the last half century. The Picea crassifolia tree growth climate relationship conducted on an elevational gradient with four different levels from upper treeline to lower treeline at the NE Tibetan Plateau. Results show that upper treeline trees show divergent growth trends and divergent responses in recent decades. Trees from lower treeline show a strengthening drought stress signal over time and no divergent growth trends within sites. This potential ecological reaction of tree populations to changing environmental conditions shows an implications for using trees to reconstruct climate, since the indiscriminate use of tree ring data from sites showing opposite responses to increasing warming could cause mis-calibration of tree ring based climate reconstructions, and over- or underestimation of carbon sequestration potential in biogeochemical models. The physiological response of Sabina przewalskii tree growth to major limiting climate factors based on the Vaganov-Shashkin (VS) model indicated that precipitation during the early growing season, especially in May and June, has significant effect on tree growth, while temperature mainly affects tree growth by warming-induced drought and by extending the growing season in the NE Tibetan Plateau. Under current and projected climate scenarios, modeling results predict an increase in radial growth of Sabina przewalskii around the Qaidam Basin, with the potential outcome that regional forests will increase their capacity to sequester carbon. However, most Picea crassifolia trees growing at lower elevations than Sabina przewalskii might be continue stressed by the warming induced drought and might decrease radial growth in future.
The six extraocular muscles (EOMs) are arranged around the eyeball as agonist-antagonist pairs performing the eye movements. The EOMs comprise a distinct muscle group that is fundamentally different from other skeletal muscle, which is reflected on many levels, such as functionality, anatomy as well as in their molecular make-up. Physiologically EOMs are considered superfast, high endurance muscles that are continuously active. In addition, EOMs contain unusual slow-tonic fibers that share features with amphibian and avian slow-tonic fibers. EOMs also express slow/cardiac isoforms of proteins and genes along with the typical isoforms of fast muscle fibers. Another striking hallmark of EOM is their differential involvement in a number of diseases. For instance, EOMs are preferentially spared in Duchenne Muscular Dystrophy (DMD). DMD is the most common fatal, genetic disease in males clinically characterized by progressive muscle wasting. Mutations in the dystrophin gene result in a destabilization of the muscle membrane causing muscle fiber damage. While all other skeletal muscles deteriorate the EOMs remain morphologically and functionally healthy. In the pathogenesis of DMD elevated Ca2+ levels are believed to be an early event and it has been shown that EOMs are protected from pharmacologically induced Ca2+ damage. The goal of this study was to characterize the spared EOMs, in particular their Ca2+ homeostasis, in the context of DMD pathology to reveal new potential therapeutic targets for the disease. A combination of physiological, molecular and biochemical methods was used to investigate the Ca2+ homeostasis of EOMs to demonstrate clear differences compared with the fast limb muscle tibialis anterior (TA). Ca2+ handling of stimulated cultured EOM myotubes suggested more efficient Ca2+ removal from the cytoplasm after induced Ca2+ influx compared with cultured myoblasts from TA. Subsequent mRNA and protein expression analyses of myoblasts and adult muscle tissue revealed high expression levels of many key Ca2+ regulating and buffering proteins in rodent EOMs compared with TA. Among these Ca2+ proteins were slow/cardiac proteins, which normally are not found in fast muscles. For instance, the sarcoplasmic Ca2+ ATPase SERCA2 was elevated along with its regulator phospholamban (PLN). Further, PLN was preferentially endogenously phosphorylated at Thr17 suggesting continuous activation of SERCA2 and possibly the fast isoform SERCA1, the main Ca2+ pumps responsible for removing Ca2+ from the cytoplasm after muscle contraction. Furthermore, Ca2+ buffers, such as calsequestrin (CASQ2) and parvalbumin (PARV) were elevated. These results suggest that EOMs are endowed with a unique and superior Ca2+ homeostasis that facilitates efficient Ca2+ buffering and removal from the cytoplasm. This is in agreement with their continuous and fast activation cycles, as well as with a potential protective mechanism in prevention of Ca2+ overload in DMD. The extreme activity patterns of EOM suggested that a high activity of store-operated Ca2+ entry (SOCE) plays a critical part to replenish Ca2+ for rapid and continuous cycles of contractions. To extend the data on general Ca2+ homeostasis and because of possible implications of store-operated Ca2+ influx and other Ca2+ influx pathways in DMD, the expression patterns of group 1 transient receptor potential (TRP) channels and the proteins Orai1 and STIM1 were studied. The TRP channels, TRPC1, TRPC6 and TRPV4 channel proteins in addition to STIM1 showed higher expression in EOM compared with TA. High TRPC1, TRPV4 and STIM1 levels could play a significant role in the high fatigue resistance, muscle differentiation and SOCE in EOM. In addition, tissue from the mdx mouse model of DMD was investigated. The only channels differentially expressed in mdx EOM compared with normal EOM were TRPM4 and TRPM7 (decreased in mdx EOM) and TRPV4 (increased in mdx EOM). Although, these changes in mdx EOM were of small magnitude, they could point toward subtle compensatory changes related to the disease process. In general, EOMs seem to be unaffected by the disease and inherently protected. In conclusion, the results in this thesis have improved the understanding of the Ca2+ homeostasis in EOMs and suggest that EOM may be better able to prevent prolonged elevation of cytoplasmic Ca2+ levels. These data may help to design new therapeutic approaches targeting Ca2+ handling proteins to ameliorate muscular dystrophy.
Transition metal complexes play a crucial role in antitumor therapy. Complexes of platinum, ruthenium as well as lanthanum and gallium have been investigated in preclinical as well as in clinical studies. The best known platinum(II) agents approved worldwide, cisplatin or carboplatin, are used in nearly 50% of all cancer therapies. This work focused on the development of new metal-based drugs that could act against human cancer cells. It was motivated in part by previous work with Cu(II) complexes, reporting new coordination compounds of SOD mimicking and cytotoxic activities. On the basis of this work we chose several commercially available heterocyclic ligands to synthesize new metal ion complexes in search of their interesting biological activity. New as well as previously reported Cu(II), Co(II), Pt(II) and Zn(II) complexes were synthesized using various ligands (1-6). Almost all chelating 2:1 ligand-metal complexes were obtained generally in water at room temperature in the reaction of metal(II) chloride with corresponding aromatic nitrogen ligands bearing an O-carboxylate group ligand. The synthesized chelating complexes were characterized by the use of spectroscopic methods, elemental analyses and HPLC chromatography and some by X-ray crystallography. Such coordination compounds are easily formed by transition metals with free orbitals d that can accept the donor electron pairs. The coordination is through the heterocyclic nitrogen and carboxylate oxygen donor atoms, which was shown by analysis of the characteristic functional groups in the IR spectra. The d-d transitions and absorption of visible light in Cu(II) and Co(II) complexes make them highly colored, blue, green or green-blue, respectively. The configuration of the coordination center was established in some cases by X-ray crystallography. Most of the already published structures possess the trans configuration. This led to the assumption that other uncrystallized complexes were also trans configured. However, X-ray data of the Cu(II) complex of 5 showed quite unexpectedly the cis configuration. On the other hand, the LC/MS experiments with the Pt(II) complex of 5 indicated that this complex exists in two isomeric forms, i.e., cis and trans at the Pt(II) center. Through the use of density functional calculations we optimized the structures and calculated the energies and dipole moments. The differences in energy for all complexes were about 6 to 15-fold lower when compared to cis and transplatin. The DFT calculations confirmed that the trans-isomers are more stable than their cis-isomers. UV-Vis stability studies with most of the synthesized complexes as well as some other Cu(II) complexes were performed to study the spectral changes over 24 h in addition of glutathione, a tripeptide present in the cancer cells and ascorbate that were added to the incubations. The results indicated time-dependent changes and instability of the complexes in the cells and their possible decomposition to lose the ligand and release the metal ion. In the case of Cu(II) complexes, reduction of Cu(II) to Cu(I) may take place. New species such as GSSG could arise and the complexes may decarboxylate, but these structures were not elucidated. The synthesized coordination metal(II) complexes were tested for their potential antiproliferative activities by using the crystal violet staining method in a panel of human cancer cell lines. Out of all complexes, three Pt(II) complexes of 2, 5 and 6 showed satisfactory activity and for these complexes the IC50 values were additionally determined in new RT-4, DAN-G and MCF-7 cancer cell lines. Interestingly, the active complexes were the chelating trans complexes which is quite unexpected, based on the difference in activities between cis and transplatin. All of the complexes were tested for their potential antimicrobial activities in comparison to the standard antibiotics on such bacterial strains as Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and yeast Candida maltosa. Co(II) complexes have been especially known to act against bacterial strains. The activity of the Co(II) complexes was indeed the highest of all metal(II) complexes. The ligand 2 (a nicotinic acid isomer) was also found active. This fact could explain why some antibacterial activity was found in the MIC assay. In addition to the complexes synthesized in this work, several novel heterocyclic metal(II) complexes of copper, ruthenium, platinum, gallium, osmium and lanthanum from other research groups were screened for their antiproliferative activity, some of which exhibited very potent activity in the cancer cell lines. In conclusion, Pt(II) complexes with bis-chelating heterocyclic carboxylate ligands represent a particularly interesting new class of compounds from the view point of their structural and biological properties.
In this thesis, it was the subject to build a setup to study the interaction of clusters with intense laser light. A magnetron sputter cluster ion source was built to create metal clusters for the planned investigations. Furthermore, a linear Paul trap setup was built in order to allow the investigation of the mentioned interaction at one specific cluster size. The whole apparatus was characterized and first experiments were performed.
This thesis aims at bridging the gap of deficient understanding of effective buffer zone management. The overall research goal of the thesis is to evaluate buffer zone effectiveness and to identify factors influencing effective buffer zone management in forest biosphere reserves. To address the multi-facetted issue of buffer zone effectiveness an integrative research design was applied. To answer the raised research questions a combination of social science (quantitative and qualitative approaches) and natural science (remote sensing) was chosen. To gain global insights into buffer zone management (research question 1) the quantitative approach of social science research was chosen. As part of a global telephone survey of BR management conducted by the research project in which the thesis was embedded, BR managers were asked to evaluate different management aspects. Between July and December 2006, managers from 225 BRs in 79 countries were interviewed, which corresponds to an overall response rate of 42 %. Answers were statistically analyzed using SPSS 17.0. To obtain detailed information of factors influencing buffer zone management (research question 2) the qualitative social science research approach was applied. A case study was conducted in the Lore Lindu Biosphere Reserve, Sulawesi, Indonesia between March and May 2008. Following the snowball sampling approach 47 semi-structured interviews and seven group discussions were carried out representing the local, sub-national, and national level associated with the BR management. These interviews and discussions provide important insights into the institutional dimensions and their interaction within the context of BR management including e.g. implementation of rules and the distribution of responsibilities for buffer zone management. Interviews were conducted in the national language Bahasa Indonesia, fully recorded, and subsequently transcribed and translated into English. Analysis was carried out with ATLAS.ti to specify categories and to formulate theorems. To evaluate buffer zone effectiveness in terms of reducing deforestation in the core area of Lore Lindu Biosphere Reserve (research question 1), satellite image analysis was performed using a GIS. A time series of LANDSAT scenes from 1972, 1983, 1999, 2002, and 2007 was used to classify homogeneous areas of forest cover to ultimately detect deforestation. Deforestation rate was computed for the periods before and after management establishment in 1998. The combination of all three research methods provided important insights into buffer zone management of BRs. Thus, based on these findings, recommendations to improve buffer zone management (research question 3) could be drawn. Overall, the evaluation of buffer zones depicts their importance for BR management effectiveness. Analysis revealed buffer zone effectiveness as important success factor, while it explicitly depends on both the implementation of the BR concept at the national level and coordination of stakeholders on the local level. As more and more PAs create buffer zones to integrate the local people, they may face similar problems. The case study from Lore Lindu exhibited important preconditions for successful buffer zone management. From a methodological perspective the thesis calls for the need of integrated research approaches across disciplines to adequately assess both buffer zone and PA effectiveness. Generally, it is recommended to pay special attention to pre-Seville BRs in the future, since most of these BRs still lack the three zone scheme. Analysis of the case study area revealed particular weaknesses in implementing central elements for effective BR management, such as the four goals of the Seville Strategy, even 15 years after inauguration. Thus, the thesis shows that not only the quantity of PAs but also the quality of its management and thus effectiveness is an important indicator for global conservation targets. Finally, it can be summarized that the idea of establishing buffer zones within BRs and PAs in general, is the right way forward to enhance PA effectiveness and to achieve global reduction of biodiversity loss. Integrating the people living within and adjacent to PAs, must be given more attention in the future. Establishment of buffer zones, where this integration and cooperation is a necessity, should be the central conservation measure, not only within BRs but also within PAs in general.