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Institute
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The present work is a cumulative dissertation that covers the research work of the author at the Department of Analytical and Physical Chemistry of Chelyabinsk State University. It contains a short description of the study and a set of attached publications in peer-reviewed journals and conference proceedings.
The phase and chemical equilibria in binary systems Me – Si
(where Me is the 4th-period transition metal) as well as Mo – Si, Mn – Ge and Fe – Ge at low temperatures were considered. The solid solubility of silicon in vanadium, chromium, manganese, iron, nickel, cobalt and copper and that of germanium in manganese and iron was estimated.
The phase equilibria in Me – Si – O, Mo – Si – O, Mn – Ge – O and Fe – Ge – O ternary systems at standard conditions were considered from a thermodynamic viewpoint. The atmospheric corrosion of transition metals silicides and manganese and iron germanides was discussed.
The chemical and electrochemical equilibria in Me – Si – H2O, Mo – Si – H2O, Mn – Ge – H2O and Fe – Ge – H2O systems were considered from a thermodynamic viewpoint. Pourbaix diagrams for some 4th-period transition metals and molybdenum, as well as for silicon, were revised. The potential – pH diagrams for Me – Si – H2O, Mo – Si – H2O, Mn – Ge – H2O and Fe – Ge – H2O systems were plotted in the first time. The corrosion-electrochemical behaviour of transition metals silicides and manganese and iron germanides in aqueous media was discussed.
The potential – pH diagrams for some siliceous brasses and bronzes (which are multicomponent alloys containing both transition metals and silicon) were plotted, and the corrosion of these alloys in aqueous media was discussed.
Method of estimation of corrosion-electrochemical behaviour of multicomponent alloys, which takes into account both thermodynamic and kinetic data and is based on mutual construction of equilibrium and polarisation potential – pH diagrams, was described. Its usage was illustrated in the example of the structural steel 20KT.
The southern Baltic Sea embodies an incomparable geological archive of the tectonic evolution of the 450 Ma old Trans‐European Suture Zone (TESZ). This WNW to NW trending suture formed during the collision of Baltica and Avalonia and has accommodated the repeatedly changing stress regimes since then, as evidenced by numerous fault zones and systems. The German offshore part in the vicinity of Rügen Island is strongly block‐faulted, with each block showing a specific geological pattern, enabling the reconstruction of the structural evolution of the area.
The work of this thesis is part of the USO working group of the University of Greifswald and the Geological Survey of Mecklenburg‐Western Pomerania, which aims to build a unified three‐dimensional tectonic model of the southern Baltic Sea area. This thesis presents the results of new structural investigations of the Arkona, Wolin and Gryfice blocks north and east of Rügen. Especially, conflicting structural analyses in the previous work are united into a consistent model.
The integrated interpretation of 144 reprocessed seismic vintage lines (original Petrobaltic data) and 23 high resolution academic seismic sections (from the Universities of Hamburg and Bremen), with additional consideration of on‐ and offshore wells, revealed 19 seismostratigraphic horizons that subdivide the succession between the Proterozoic basement and the Upper Cretaceous. Up to 100 faults of superior fault zones and systems control the tectonic situation. Besides NW trending deep faults formed during the Palaeozoic, for instance the Wiek and Nord Jasmund faults, and NNW trending Mesozoic faults and flexures that belong to the Western Pomeranian Fault System, other major faults such as the Adler‐Kamień Fault Zone document the polyphase evolution of this area.
The restoration of selected seismic sections support the evaluation of separately generated faults and their reactivation, leading to a subdivision of the tectonic evolution of the area into six stages:
(1) The Caledonian Orogeny (Ordovician/Silurian) was accompanied by a NE‐SW compression, resulting in the formation of the TESZ and an accretionary wedge within the upper crust. (2) The following S to SW trending extension of the Variscan Foreland (Devonian/Carboniferous) triggered the
evolution of the Middle Devonian Old Red Rügen Basin south of the Wiek Fault. Further WNW to NW trending faults (e.g. Nord Jasmund Fault) subdivided the basin. (3) The advancing Variscan Orogeny (Late Carboniferous) caused an increasing NE‐SW orientated compression and subsequently reactivated faults and tilted blocks (e.g. Lohme Sub‐block). (4) The North German Basin and Mid Polish Trough formed by thermic subsidence in the S to SE of the research area during the Permo‐Carboniferous. Simultaneously, the evolution of the Gryfice Graben as part of the Teisseyre‐Tornquist Zone commenced. (5) Due to the Arctic‐North Atlantic Rifting an E‐W trending extension increased. Consequently, grabens such as the Gryfice Graben continued their subsidence. As the stress system rotated counter‐clockwise, the shear strength increased along the NE trending faults. The Western Pomeranian Fault System developed due to intense transtension during the Keuper and Jurassic, and is characterised by pull‐apart structures. (6) In the Upper Cretaceous, a NE‐SW compression, forced by the Africa‐Iberia‐Europe convergence, triggered the reactivation of faults and flexures as reverse ones, the inversion of grabens (e.g. Gryfice Graben), and the formation of anticlines, for instance at the Wolin Block.
This thesis combines the calculation of gridded time structure maps and a detailed fault pattern analysis, and represents the base for a velocity‐ and subsequently depth‐based 3D modelling.
The proteasome is a major part of the ubiquitin-proteasome-system playing an important role in cell homeostasis due to its protein quality control function. Moreover, the proteasome is involved in cell cycle regulation and in the regulation of transcription factors. Upon induction of interferons, or treatment with lipopolysaccharides, an isoform of the standard-proteasome is composed, named immunoproteasome (i-proteasome). The i-proteasome is constitutively expressed in immune cells and deficiency of proteolytic subunits of this multiprotein complex has been associated with a poor outcome during infectious diseases. I-proteasome-deficiency has been shown to result in reduced MHC class I presentation. Using mice which are deficient for all three proteolytic active subunits LMP2, MECL-1 and LMP7, we could demonstrate that i-proteasome-deficiency lead to an altered recruitment of immune cells to the CNS when challenged with the intracellular parasite Toxoplasma gondii, resulting in increased frequencies of neutrophils and other cells of myeloid origin. The shift to reduced frequencies of CD45highCD11blow lymphocytes can be further explained by a decreased migratory capacity of i-proteasome-deficient CD8+ T cells. In contrast to previous studies using other pathogens, effector function of CD8+ as well as CD4+ T cells, measured by frequencies of IFNγ, TNF, IL-2 and granzyme B producing cells, were not impaired in these mice, whereas induction of CD4+ Tregs was strongly reduced. In addition, we found that parasite control was comparable to control mice and that i-proteasome deletion caused an overall pro-inflammatory cytokine milieu within the brain. Our results indicate that i-proteasome-deficiency lead to prolonged tissue inflammation during T. gondii infection which could be an explanation for the more severe course of disease observed in these mice.
The Src homology domain containing phosphatase 2 (SHP2) is a tyrosine phosphatase modulating several signaling pathways and therefore has an influence in cell cycle, differentiation, proliferation and cell activation. However, SHP2 is assumed to play a negative role during T-cell activation as the phosphatase has been shown to inhibit T-cell receptor-induced signaling cascades. Although, various gain-of-function mutations in the SH2 or PTP domain of this phosphatase, such as D61Y, have been associated with myeloproliferative diseases such as juvenile myelomonocytic leukemia (JMML), effects of such mutations on T cells have not been addressed in scientific literature so far. Therefore, in the second part of this thesis we could demonstrate that D61Y mutation in the SH2 domain of SHP2 did not cause JMML pathology when only introduced into T cells. Especially in aged mice, T cells of SHP2 mutant mice showed an increased expression of cell adhesion molecule CD44. In accordance with these findings, we observed increased influenza A virus-specific T cells in the bone marrow of SHP2 D61Y mutant mice, indicating a role of the phosphatase in memory formation or maintenance of CD8+ Tem. Although SHP2D61Y mice revealed a comparable viral clearance, IFNγ production of virus experienced CD4+ and CD8+ T cells was diminished compared to control mice, underlining a negative involvement of the phosphatase in the JAK/STAT1 signaling axis as suggested before by studies using mice with SHP2-/- T cells.
Background: Sedentary behavior (SB) is a modifiable behavior with increasing prevalence worldwide. There is emerging evidence that time spend in SB and the manner in which SB is accumulated over time is associated with cardiovascular and cardiometabolic health. The requirement for SB data to be accurately measured is minimization, or at least accurate quantification of human-related sources of measurement errors such as accelerometer measurement reactivity (AMR). The present thesis was to examine SB and their associations with cardiovascular and cardiometabolic health, and to focus on challenges related to the assessment of SB. The first aim of the thesis was to identify patterns of SB describing how individuals accumulate their time spend in SB day-by-day over one week, and to examine how these patterns are associated with cardiorespiratory fitness as a marker for cardiovascular health (paper 1). The second aim of the thesis was to examine the multiple types of SB, and how this is associated with a clustered cardiometabolic risk score (CMRS; paper 2). The third aim of the thesis was to examine AMR and the reproducibility in SB and physical activity (PA) in two measurement periods, and to quantify AMR as a confounder for the estimation of the reproducibility of SB and PA data (paper 3).
Methods: The three papers were based on data of two different studies. For study 1, 1165 individuals aged 40 to 75 years were recruited in three different settings. Among these, 582 participated in a cardiovascular risk factor screening program including cardiopulmonary exercise testing. For the analyses of paper 1, 170 participants were eligible, agreed to wear an accelerometer, fulfilled the wearing regime, and completed the study period by wearing the accelerometer for seven consecutive days. Patterns in accelerometer data were classified based on time spent in SB per day applying growth mixture modeling. Model‐implied class‐specific peak oxygen uptake (VO2peak) means were compared using adjusted equality test of means (paper 1). The underlying study of paper 2 and 3 were based on data of a pilot study aiming to investigate the feasibility of a brief tailored letter intervention to increase PA and to reduce SB during leisure time. Among the individuals who agreed to be contacted again in study 1, a random sample of those aged between 40 and 65 years was drawn. Of those, 175 attended in a cardiovascular examination program. Assessment included giving blood sample, standardized measurement of blood pressure, waist circumference, body weight, and height at baseline, and after twelve months. Further, they agreed to complete a paper-pencil questionnaire on SB (Last 7-d Sedentary Behavior Questionnaire, SIT-Q-7d) and PA (International Physical Activity Questionnaire, IPAQ), and to receive seven-day accelerometery at baseline, and after 12 months. In addition, self-administered assessments were conducted at months one, three, four, and six after baseline. Only individuals of a random subsample (= intervention group) received up to three letters tailored to their self-reported SB and PA at months one, three, and four. For paper 2, associations between SBs and a clustered cardiometabolic risk score (CMRS) were analyzed using linear as well as quantile regression. To account for missing values at baseline, multiple imputations using chained equations were performed resulting in a total sample of 173 participants. Paper 3 comprised data of 136 individuals who participated at the baseline and twelve months assessments, and fulfilled the wearing regime. AMR was examined using latent growth modeling in each measurement period. Intraclass correlations (ICC) were calculated to examine the reproducibility of SB and PA data using two-level mixed-effects linear regression analyses.
Results: Results of paper 1 revealed four patterns of SB: 'High, stable', 'Low, increase', 'Low, decrease', and 'High, decrease'. Persons in the class 'High, stable' had significantly lower VO2peak values (M = 25.0 mL/kg/min, SD = 0.6) compared to persons in the class 'Low, increase' (M = 30.5 mL/kg/min, SD = 3.6; p = 0.001), in the class 'Low, decrease' (M = 30.1 mL/kg/min, SD = 5.0; p = 0.009), and in the class High, decrease' (M = 29.6 mL/kg/min, SD = 5.9; p = 0.032), respectively. No differences among the other classes were found. In paper 2, results revealed that the only factor positively associated with a CMRS in all regression models was watching television. Depending on the regression analysis approach used, other leisure-time SBs showed inconsistent (using a computer), or no associations (reading and socializing) with a CMRS. In paper 3, results revealed that time spent in SB increased (baseline: b = 2.3 min/d; after 12 months: b = 3.8 min/d), and time spent in light PA decreased (b = 2.0 min/day; b = 3.3 min/d). However, moderate-to-vigorous PA remained unchanged. Accelerometer wear time was reduced (b = 4.6 min/d) only at baseline. The ICC coefficients ranged from 0.42 (95% CI = 0.29 - 0.57) for accelerometer wear time to 0.70 (95% CI = 0.61 - 0.78) for moderate-to-vigorous PA. None of the regression models identified a reactivity indicator as a confounder for the reproducibility of SB and PA data.
Conclusions: The present thesis highlights SB in the field of cardiovascular and cardiometabolic research that have implications for future research. Individuals sit for different purposes and durations in multiple life domains, and the time spent in SB is accumulated in different patterns over time. Therefore, research should consider the fact that SB is embedded in an individual's daily life routine, hence might have differential effects on cardiovascular and cardiometabolic health. Further, methodological aspects have to be considered when dealing with SB. In order to detect how SB is 'independently' associated to an individual's health, an accurate measurement of SB is fundamental. Therefore, human-related sources of bias such as AMR should be taken into account when either planning studies or when interpreting data drawn from analysis of SB data.
The first part of my work comprises empirical findings and theoretical foundations on stress in its historical development and socio-emotional and behavioural factors.
The first study of my dissertation focuses on the relationship between perceived stress in adolescence, the context variables of perceived helpfulness and competition and socio-emotional and behavioural strengths and difficulties (i.e., emotional problems, symptoms of hyperactivity, problems with peers, prosocial behaviour and conduct problems) from early to middle adolescence. I postulated a moderation or mediation of the effect of perceived stress on socio-emotional and behavioural strengths and difficulties through the two context variables. My hypotheses were tested using a latent moderating structural equation model (moderation analysis) and a multi-group structural equation model taking into account the gender and age of the students (mediation analysis). The theoretical basis of my first study is the transactional stress model by Lazarus and Folkman (1984).
The second study of my dissertation is dedicated to the question whether perceived stress is a moderator in the relationship between depressive symptoms in early adolescence and socio-emotional and behavioural strengths and difficulties in middle adolescence. Based on the cognitive vulnerability-transactional stress theory of Hankin and Abramson (2001), which assumes reciprocal and dynamic relationships between the individual and the environment, I investigated this question and tested the relationships using a latent moderating structural equation model.
The third study of my dissertation is based on Bronfenbrenner’s socio-ecological model (1975). Using a cross-lagged panel design, I investigate the within time and longitudinal relationships between variables of emotional (in-)stability (i.e., depressive symptoms, perceived stress and loneliness) and socio-environmental factors (i.e., sense of belonging, student-student and teacher-student-relationship) from early to middle adolescence.
At the end of my work there is a summary of all results, a discussion and an outlook for future research.
Medical doctors sometimes make diagnoses in persons who are not their patients and who did not ask for their medical opinion, e.g., when an off-duty dermatologist diagnoses melanoma in a stranger, outside of the hospital setting. These diagnoses are referred to as unsolicited medical opinions.
The unsolicited medical opinion raises several ethical questions. Most importantly, it poses a moral challenge for the physician: a possible disease, which may lead to a serious loss of health, is recognised in a person who is not the physician’s patient, outside of the formal medical context. The fundamental ethical question addressed in this dissertation is: Does a medical doctor who makes a clinical diagnosis in a stranger, outside of the formal medical context, have an ethical obligation to offer an unsolicited medical opinion?
This ethical question involves some related questions: If physicians do have an ethical obligation to offer an unsolicited medical opinion, are there any limiting factors to this obligation, which would justify not acting? A more practical question is also raised: How should a physician approach the person in whom an unsolicited diagnosis is made?
The cumulative dissertation is based on three publications addressing the unsolicited medical opinion. Firstly, the unsolicited medical opinion is explored from the perspective of utilitarianism, and a utilitarian argument is made in favour of offering an unsolicited medical opinion. Secondly, the topic is placed in the context of the existing scientific literature and analysed from the perspective of several ethical theories: virtue ethics, care ethics, principlism and contract theory. Lastly, the unsolicited medical opinion is discussed in the context of “medically unknown symptoms”. As in the central argument of this thesis, a utilitarian principle is applied and an argument made in favour of an unsolicited mental health diagnosis.
The term diabetes mellitus comprises a group of metabolic diseases all distinguished by their main characteristic hyperglycaemia. With a steadily increasing prevalence diabetes displays an enormous burden for patients and health systems and is therefore of special interest for research. The development of the two main types of diabetes, type 1 and type 2, is closely linked to the formation of reactive species, especially hydrogen peroxide, inside different compartments of pancreatic beta cells. However, these cells are especially vulnerable towards oxidative stress mediated by hydrogen peroxide due to a low expression of antioxidative enzymes.
The main aims of the present thesis were to analyse the intracellular generation and to enable the site-specific detection of hydrogen peroxide to evaluate its role in the delicate equilibrium between redox signalling and oxidative stress under certain pathophysiological conditions, and moreover to monitor its movement through compartments and subcellular membranes of insulin-producing cells. Additionally, a new methodology for an artificial site-specific generation of hydrogen peroxide inside living cells was developed.
Global climate change is occurring all over the world, but in the Arctic the climate is changing more rapidly and drastically than in many other parts of our planet. Many species that are already at their climatic limit need to adapt to recent climate conditions or migrate in order to not go extinct. The possibilities of adaption include phenotypic plasticity and adaptation to various extents. This is also the case for white spruce P. glauca, which belongs to the conifers and thus in the largest group of gymnosperms still living today. Among the approx. 600 extant conifer species white spruce is one of the most widespread trees in North American boreal forests. Its range extends from 69° N in the Canadian Northwest Territories to the Great Lakes at about 44° N, where it occurs from sea level to an altitude of about 1520 m (Burns and Honkala, 1990). Site related, climate-dependent differences in white spruce reproduction can be seen as a strategy to survive under the harsh climatic conditions at Alaska's treelines: Besides sexual reproduction, the vegetative propagation occurs in the white spruce as an additional reproductive mechanism. This can be realized by "layering" when the lower branches of the tree crown touch the ground and develop roots to later grow as a separate individual with or without a connection to the mother tree. Known as other mechanisms of vegetative propagation are also the rooting of fallen trees which were not completely uprooted, and the "root suckering", in which new shoots sprout from the roots of the tree. However, the latter was not yet observed in the genus Picea. With the help of short, repetitive, non-coding sequences in the genome, which are therefore not subject to selection and are called microsatellites, these clones can be determined by genotyping.
For this purpose, using different polymorphic microsatellites, an individual multilocus genotype is created for each tree, by means of which it can be compared with all other trees of the same species.
In the first part of this work (article I), the occurrence of clones in three study areas at Alaskan treelines are examined and the reasons for their appearance in variable numbers are discussed. For this purpose, 2571 white spruces (P. glauca) were genotyped and their position was determined via differential GPS in the field. The percentage of clonal trees is higher in areas with harsh climatic conditions and correlates with the height of the lowest branches of the tree crown. This suggests that the vegetative propagation of white spruce is a backup strategy for times when climatic conditions hamper sexual reproduction. The correlation between clone numbers and tree crown height suggests "layering" as the main mechanism for cloning whereas selection for vegetative reproduction seems to be very unlikely shown by the results for genetic differentiation between the clonal and the singleton trees in this study.
In the second part of this work (articles II and III), the influence of environmental factors and phenotypic traits on the mycobiome of the needles (including all fungi living on (epiphytic) and in (endophytic) the needles) in our study areas in Alaska was investigated. The mycobiome of the white spruce needles was chosen as a proxy for the parasite infection rate by fungi and thus serves as a fitness parameter. For this purpose, all epiphytic and endophytic fungal species were analyzed by a metabarcoding analysis.
In article II, 48 trees of one study area at Alaska’s northern treeline (Brooks Range) were examined for differences in mycobiome due to genetic differentiation, phenotypic characteristics and / or habitat characteristics. The trees used for this study were sampled from two adjacent plots on a south-facing mountain slope with an elevation gradient from 875 to 950 meters above sea level. It could be shown that, in contrast to the trees genotype, the height above sea level, the mountain slope, as well as the height and age of the trees have a significant impact on the mycobiome. The genetic differentiation between the tree individuals, however, showed no significant effect.
Based on article II we examined the mycobiome composition of a total of 96 trees in 2 plots (16 trees each) at three sites in Alaska over a distance of 500 kilometers. Additionally, we sampled needles of two different ages for each tree (current year and three years old needles) summing up to 192 samples in total. The incentive of this study (article III) was to investigate the influence of origin and age of spruce needles on their mycobiome and if there is a genetic predisposition that is related to the fungal species community. In addition, the sampling design was improved by collecting needles from all four orientations (North, South, East and West) and sampling trees at a standardized distance to each other to avoid systematic errors. Comparable to article II the influence of the trees genetics on the species community of the epiphytic and endophytic fungi of the white spruce needles seems to be very unlikely. In contrast, a significant influence of the geographic origin and the needle age on the species structure of the needle inhabiting fungal species was found. The phenotypic tree traits height and dbh (diameter at breast height) had only minor influence and did in fact explain less than 2% of the mycobiome variance. Using Illumina sequencing, 10.2 million reads from the nucleotide sequence between the internal transcribed spacer (ITS) genes could be obtained, which yielded in 1575 ribotypes (called operational taxonomic unit, OTU) for the fungi. These were compared with a reference database to compare and assign them to known fungal species. For example, 942 OTUs with >95% similarity could be identified as known species, with 1975 samples identified on genus level and 2683 when determined to family level. The most pronounced difference between the two studies (article II and III) were due to the fungal species of the class of Pucciniomycetes, more specifically the genus Chrysomyxa which belongs to the rust fungi and is plant pathogenic. In the study of article II (sampling in 2012), Pucciniomycetes accounted for only a minor portion of the assigned DNA sequences. In the second study (article III, sampling in 2015) they accounted for more than half of all basidiomycetes found, which in turn contain 20.0% of all DNA sequences, the second largest phylum found beside Ascomycetes (51.4%).
Central to this thesis are so-called G-quadruplex (G4) nucleic acids. These unusual structures have recently moved into the scientific limelight - mostly due to their prevalence in the human genome. Incidentally, the vast majority of G4-prone sequences is found in telomeric regions and in the promoter sequences of a large number of cancer-related genes.
Furthermore, recent studies suggest a wide applicability of these structures as therapeutic and functional agents, though the technology is still in its infancy with only a few oligonucleotides in clinical trials. Notably, G-quadruplexes are highly polymorphous, exhibiting different topologies and conformations based on sequence, solution condition and molecularity. Therefore, rational design of such structures with specific, topology-encoded functions demands a comprehensive understanding of the underlying folding parameters.
As the folding process is the result of a whole orchestra of parameters with synergistic effects, the herein proposed approach to understand the G4 structural arrangement concentrates on native G4-forming sequences with well-defined topologies. Perturbations of these structures by rational nucleotide substitutions allow for the observation of discrete effects on the folding pathway and on the resulting overall topology.
The method chosen for primary investigation in the following studies on G4 architectures was Nuclear Magnetic Resonance (NMR) as it is the most powerful tool for structure elucidation in liquids. Unique to this technique, it permits the observation of discrete species in mixtures by distinct perturbations at the atomic level as well as valuable insights into the molecular dynamics.
The included publications study the effects of site-specific bromine substitutions on native quadruplex scaffolds, thereby successfully inducing new structures. These expand the G4 structural landscape but also enhance our understanding of the driving forces in G4 folding.
Escherichia coli has been commonly used as a platform for recombinant protein production and accounts for approximately 30% of current biopharmaceuticals on the market. Nowadays, many recombinant proteins require post-translational modifications which E. coli normally cannot facilitate. Therefore, novel technological advancements are unceasingly being developed to improve the E. coli expression system. In this work, some of the most recently engineered platforms for the production of disulfide bond-containing proteins were used to study the E. coli proteome under heterologous protein production stress. The effects of protein secretion via the Sec and Tat translocation pathways were examined using a comparative LC-MS/MS analysis. The E. coli proteome responds to foreign protein production by activation of several overlapping stress responses with a high degree of interaction. In consequence, a number of important cellular processes such as cellular metabolism, protein transport, redox state of the cytoplasm and membrane structure are altered by the production stress. These changes lead to the reduction of cellular growth and recombinant product yields. Resolving the identified bottlenecks will increase the efficiency of recombinant protein expression processes in E. coli.
Reversible posttranslational modifications play an important role during the regulation of many central processes in bacterial cells. Protein phosphorylation, in particular, can influence signal transduction processes and thus enables a distinct reaction of the cell to different stress and environmental conditions. In the case of the human pathogen Staphylococcus aureus, protein phosphorylation is involved in the adaptation to changing conditions during colonisation of human hosts. For this reason, the investigation of phosphorylations in S. aureus allows a better understanding of pathophysiology and virulence of this organism. Apart from stable phosphorylations at the amino acids serine, threonine and tyrosine, insights into energy-rich phosphorylations, for instance at arginine residues, gain more and more scientific attention. For this reason, one purpose of this study was the investigation of incidence and physiological relevance of this protein modification at a global scale. Firstly, the analysis of this modification was methodically optimised resulting in the identification of eight arginine phosphorylations in wild type cells of S. aureus COL. Secondly, the deletion mutant ΔptpB missing the gene that codes for an arginine phosphatase, was analysed. The characterisation of PtpB in vitro proved its activity and specificity towards arginine phosphorylations. This enabled the global analysis of the phosphoproteome with a focus on arginine phosphorylations. In addition to the optimisation of the phosphopeptide enrichment as part of the sample preparation, the data analysis process was adapted to the special challenges of energy-rich phosphorylations. Here, classical database search was extended by spectral library based analyses. In addition, synthetic peptides allow the generation of high quality mass spectra and the verification of database based evaluation strategies to ensure the quality of the spectral library. Next, S. aureus COL was cultivated under various conditions and several subcellular fractions were analysed with the aim to cover a broad part of the proteome. The combination of the spectra of synthetic peptides, the spectra of non-phosphorylated peptides from extensive cultivation experiments and the spectra of enriched phosphopeptides rendered the construction of a spectral library possible. This contained 2,270 proteins out of which 392 were found to be phosphorylated. A comparison of the database based analysis with spectral library based analysis showed the advantages of the latter when comparing the reproducibility of biological replicates. Thereby a permanent issue in phosphoproteomics was investigated. Hence, spectral libraries were used for the analysis of the phosphoproteome of S. aureus under control and stress conditions. 215 arginine phosphosites were identified within the mutant under control conditions and 117 under oxidative stress conditions. Oxidative stress was chosen because phenotypic characterisation of the mutant revealed that the most distinct growth changes in comparison with the wild type occurred after oxidative stress. These phenotypic changes were quantitatively approached in the last part of this work. Total proteome quantification of the wild type and mutant under control and stress conditions revealed an influence of the ptpB deletion on amino acid metabolism, oxidative stress response and virulence. The quantification of phosphopeptides by means of a combination of spectral library with Census based analysis finally confirmed the observations made during total proteome quantification.
Profiling the activity and hepatotoxicity of flupirtine through medicinal chemistry approaches
(2019)
Drug induced liver injury (DILI) and tissue discoloration led to the recent discontinuation of the therapeutic use of the closely related drugs flupirtine and retigabine, respectively. Experience gained with these drugs strongly suggests that heterodimer, voltage‐gated potassium channels 2 and 3 (KV2/3) are valid targets for effective treatment of pain and epilepsy. Because the adverse effects are not related to the mechanism of action, it appears promising to investigate chemical modifications of these clinically validated, drug‐like leads. In the present retro metabolic drug design study, a series of 44 compounds were
synthesized and characterized with regards to KV7.2/3 opening activity and efficacy. The most active compounds displays excellent potency (EC50 = 4 nM) and efficacy (154%) as an Kv7.2/3 opener. Limited aqeous solubility hampered toxicity testing at concentrations higher than 63 μM, but this concentration was nontoxic to two hepatocellular cell ilnes (HEP‐G2 and TAMH) in culture.
In times of recent climate change, mechanisms to deal with different environments (e.g. via dispersal to other habitats, or via in-situ responses such as genetic adaptation or phenotypic plasticity) are essential. In regions showing seasonality, organisms are already adapted to regular and, thus, often predictable environmental changes. One well-known strategy to survive periods of food shortage, especially during the winter, is hibernation. Although hibernation is already an adaptation to overcome unfavourable conditions, the optimal timing of hibernation to match for example food abundance peaks is likely to be influenced by changing climatic conditions, as expected during human-induced global change. Thus, the ability to respond to changes in optimal timing of hibernation can be crucial for organisms. All hibernators are positioned at the slow end of the slow-fast life history continuum. Longevity combined with a low annual reproductive output can result in slow recovery from population crashes and is expected to be associated with slow genetic adaptation. Therefore, it is assumed that phenotypic plasticity, a rather rapid and sometimes reversible process, is a crucial mechanism in long-lived organisms to adapt to changing environments. However, how differences in individual hibernation behaviour influence mortality and whether individuals are plastic with respect to their hibernation behaviour are largely unknown.
Recent studies suggest that climatic change can influence hibernation behaviour in various species differently, in a positive or negative way. Female Columbian ground squirrels (Urocitellus columbianus) delayed their emergence from hibernation with later snow melt and lower spring temperatures. Next to the environmental impact, emergence date showed a moderate heritability in female Columbian ground squirrels. Yellow-bellied marmots (Marmota flaviventris) emerged earlier from hibernation with warmer spring temperatures which resulted in a longer growing period for their offspring and, therefore, higher survival rates. In contrast, in alpine marmots (Marmota marmota) lower snow cover due to higher temperatures and, thus, less isolation led to lower juvenile survival. Negative effects, such as reduced juvenile survival, would be of high concern, especially for long-lived species with a low reproductive output.
Bats are exceptionally long-lived compared to other mammals of the same size and often show a low reproductive output with one offspring per year. This is especially true in the temperate zone where bats, furthermore, are characterized by seasonality and depend on hibernation during winter period to survive food and water shortage. Because bats are of high conservation concern it is of prime importance to understand their ability to respond to different climatic conditions and associated mortality costs.
The basis of this study was a five-year data set of 1047 RFID-tagged individuals from two bat species, Natterer’s bats (Myotis nattereri) and Daubenton’s bats (Myotis daubentonii), that were automatically tracked when entering or leaving the joint hibernaculum, “Brunnen Meyer”, located in north-western Germany. The two species are similar sized, share demographical traits and often occupy the same areas. Nevertheless, they differ in their foraging strategy and activity pattern during hibernation period. Natterer’s bats are able to glean insects from surfaces, even at low temperatures. Daubenton’s bats depend on flying arthropods and, thus, warmer temperatures. And indeed there is evidence that Natterer’s bats are able to hunt during hibernation period, while in Daubenton’s bats a lack of feeding during the hibernation period is suggested. Furthermore, Natterer’s bats are characterized by a higher activity at the hibernaculum throughout the hibernation period, while Daubenton’s bats on average arrive earlier, stay inactive through the winter and leave later in spring.
In both species, the aim was to investigate the impact of their individual hibernation behaviour, precisely the timing of departure in late winter and early spring, on mortality, their adjustment of departure timing to the North Atlantic Oscillation Index (NAO), as well as differences within and between the two species from 2011 until 2015.
To later on estimate the potential mortality costs of departure timing, gaining knowledge about the seasonal survival pattern (winter vs. summer) in the two species was a first necessity. In birds, particularly small species were described as winter-regulated populations with a higher mortality during winter. In contrast, in hibernating mammal species, such as bats, a relatively lower or similar winter survival compared to summer survival was shown. In this study, the analysed data demonstrated that the winter 2010/2011 was exceptionally catastrophic in Natterer’s bats and did not impact Daubenton’s bats. When excluding this catastrophic winter in Natterer’ bats, our results revealed a stable winter-summer-survival difference (higher winter and lower summer survival) in adult Natterer’s and Daubenton’s bats, with inter-annual variation in the level of survival which indicates a potential environmental impact on survival. This winter-summer survival pattern is in line with the survival pattern shown for other hibernators. Juveniles always had a lower survival rate than adult bats in both species. Nevertheless, the extent to which the species differ between seasons and age classes was stronger in Daubenton’s bats. They always showed a slightly higher winter survival and a lower summer survival than Natterer’s bats. Together with the catastrophic winter 2010/2011 in Natterer’s bats, this indicates a species-specific sensitivity to the timing of specific weather events which is in line with their foraging strategies and activity pattern during hibernation period.
With respect to emergence behaviour from the hibernaculum, the results of this study suggest considerable differences among individuals within as well as between bat species. In comparison to Daubenton’s bats, Natterer’s bats tuned their emergence more closely to weather conditions, specifically the NAO, a large scale weather index related to winter severity, and showed individual variation in behavioural plasticity. In Daubenton’s bats only the females responded to changing conditions and left earlier in individually-experienced warmer and milder winters, comparable to Natterer’s bats females. A potential reason might be reproductive advantages for the females resulting in a longer growing period for their offspring. The shown higher winter survival in adult bats of both species indicated already higher energy expenditure outside the hibernaculum. Thus, leaving early, being active and staying outside longer by itself bore a risk (exposure risk effect). Under consideration of longer exposure times, early departing individuals had on top of that an increased risk to die. This was not given in each year, but a species- and year-specific pattern was revealed. Natterer’s bats were only significantly affected by early departure in 2011, while the remaining years show no significant additional risk of leaving early. In Daubenton’s bats, the years 2014 and 2015 were associated with a significantly higher mortality of leaving early. This is in line with the hypothesis that Daubenton’s bats might not be able to hunt for insects leaving too early and do so as a best out of a bad job. Nevertheless, the year-specific pattern suggests that early bats might profit from advantageous weather conditions during early spring.
An additional hint for an environmental impact on early bat survival in at least Daubenton’s bats is that the median proportion of night hours above 3 °C within five days after departure was included in the model with the lowest AIC. However, the effect was not strong enough to be selected as the best model and, therefore, further analyses are needed to investigate this first hint.
In conclusion, the reduced winter survival of juveniles compared to adults highlights the importance of considering age class effects in studies that investigate seasonal survival patterns. The stable species-specific winter-summer-survival difference with a higher winter survival compared to summer survival, as well as the one catastrophic winter in Natterer’s bats underline the importance of including seasonal survival patterns in assessing potential fitness costs of changed behaviour. Furthermore, our results suggest that long-lived hibernating bat species have the potential to plastically adjust to changing climatic conditions, but this potential differs between species. Among-individual differences in emergence together with species-specific mortality costs of early emergence suggest the potential for natural selection to shape hibernation phenology. In summary, our findings suggest species-, population- and group-specific differences in the ability to respond to changing environments and, therefore, underline the necessity to further investigate local responses in various organisms to estimate consequences of recent climate change on a wider range.
Phylogeny of the Koi herpesvirus and development of a vaccine against the Koi herpesvirus disease
(2019)
The aim of this presented dissertation was a stable, live attenuated and protective KHV usable as vaccine. Moreover this vaccine should by cost effective and easy to apply. Differentiation of infected and vaccinated animals was preferred by genetic and / or serological means. After achieving an attenuated virus, whole genome sequencing should be done to examine the genetic of the vaccine as one feature of biosafety. Besides biosafety additional knowledge on the virulence of Alloherpesviruses, especially of KHV was anticipated. Additionally the diagnostics of KHV and KHVD should be improved to increase reliability and to gain more insights into the relationship of different KHVs and hopefully to detect the source of an outbreak.
Molybdenum dependent enzymes are involved in essential metabolic transformations in bacteria, plants, and human beings. The extreme instability of the molybdenum cofactor (Moco) prevents its use as an effective treatment for patients with a Moco deficiency. Therefore, the design, develop and execute the artificial molybdenum cofactor models are essential.
In the present thesis, the asymmetric molybdopterin (mpt) model precursors with oxygen functionality and various electronic structures and their Moco model complexes mimicking the natural cofactor have been synthesized and comprehensively investigated through multi-nuclear NMR, MS, IR, resonance Raman, X-ray crystallography, UV-Vis, and electrochemical methods. Notably, the asymmetrically substituted dithiolenes in this thesis are confirmed through a significant push-pull effect, which is tuning its electronic structure. The redox behavior of Moco model complexes was investigated by temperature-dependent cyclic voltammetry. Electronic and vibrational spectral studies were investigated in detail to understand substituents effect on the electronic structure of model complexes and to elucidate roles of mpt in catalysis. Since the model complexes can be considered as structural models for the Moco dependent oxidoreductases, catalytic oxygen atom transfer (OAT) reactions in DMSO/PPh3 were investigated.
The main focus of the present thesis was achieved through the development of various synthetic routes that address phosphonate bearing dithiolene ligands, inspiring the natural mpt. Simultaneously the Minisci protocol was applied for the synthesis of new pterin ketophosphonates, taking into consideration the essential aspects of the natural molybdopterin, including the phosphate anchor group. Even though some aspects of this protocol require further optimizations, but the mentioned synthetic route has exceptional potential and flexibility.
In acinar cells, cellular organelles like zymogene granule, mitochondria, endoplasmic reticulum and lysosome functions in coordinate way in order to synthesize and secrets large amounts of digestive enzyme. Dysfunction of this organelle, results into enzyme activation within acinar cell; ultimately, acute pancreatitis. While previous studies reported that mitochondrial function is disrupt but mechanism of clearance of these mitochondria remains unknown during pancreatitis. Here we reported that PINK1 and Parkin mediated pathway is activated during pancreatitis and clears dysfunctional mitochondria in-vivo. PINK1 or Parkin deficient acinar cell had energy crisis, decreased ATP production and altered acinar cell fate in-vitro. Inhibiting clearance of dysfunctional mitochondria aggravates experimental pancreatitis severity and delays regeneration/recovery of exocrine tissue after disease via PARIS-PGC-1α pathway. While an attempt to explore therapeutic target of PARIS-PGC-1α pathway by treatment of SRT1720 rescued experimental pancreatitis. Together, PINK1 and Parkin, restricts exocrine pancreatic damage in pancreatitis and accelerates tissue recovery after disease.
In our retrospective study we researched for possible injuries to the eye and orbit in patients who suffered from polytrauma. We assessed 6,000 patients with severe trauma, who were treated at the Unfallkrankenhaus Berlin (UKB) between February 2006 and August 2014. Out of them, 1,061 maxillofacial CT scans were performed additionally to a whole-body scan as further injuries to eye and/or orbit could clinically not be excluded. We used a systemic diagnostic workup to examine the frequency and severity of a trauma to osseous and soft tissue structures of the orbit. For the assessment of the bony orbital walls we included the detection of a fracture gap, a rough dislocation of bony fragments as well as the detonation of osseous sutures between facial bones. Concerning the orbital soft tissue structures we looked at injuries of the ocular globe including the lens, extraocular muscles, optic nerve and orbital vessels. Complementary, we collected clinical data of eye examinations of our patients by using the medical information system (MIS) software medico. We appraised the ophthalmic diagnostic findings based on three criteria: the intraocular pressure (IOP), the vision and eye movements and recorded whether surgery or conservative treatment was conducted.
Out of 1,061 maxillofacial CT images, 811 were excluded. 668 patients did not have a trauma to the midface and 143 patients only showed fractures of the nose and/or jaw. The remaining 250 patients revealed traumata to the orbit: 149 CT scans showed fractures of the orbital cavity without participation of soft tissue structures. Three patients presented with pure soft tissue traumata to the eye and 98 scans displayed combined injuries of bones and orbital soft tissue structures. The right orbit was concerned in 35.6%, the left orbit in 32.8% and both orbits in 31.6% of cases. The prevailing type of fracture was the single wall fracture, followed by two- and three-walled fractures. In the majority of cases the orbital roof, floor or lateral wall were concerned. Besides blow-out fractures, we detected characteristic fractures as the tripod fracture and Le Fort 2°. Regarding the soft tissue traumata of 101 CT scans, we detected an unshaped vitreous body in 23.8% and a (partially) ruptured globe in 6.9%. The ocular lens was dislocated in six cases (5.9%). A foreign body pre-orbital and within the conus was found three times. Considering the extraocular muscles, we discovered that 44.6% of muscles were dislocated. In 7.9% extraocular muscles were pierced by bone, in one case the muscle was pierced by a foreign body. Searching for structural alterations of the optic nerve, 12.9% of 101 scans presented an elongated optic nerve and 9.9% revealed an altered morphology. One nerve was transected by a metallic foreign body. Upon closer inspection of orbital vessels, we detected 9.9% prominent ophthalmic veins and 5.9% posttraumatic dCCF out of 101 CT scans. The results of the clinical eye examinations showed that 19.2% of the collective of 250 patients presented with an increased IOP. 4.8% of 250 patients had a reduced or lost vision and 10% of patients had suffered from a limited ocular movement after trauma to the midface.
In conclusion, approximately 9.5% from 1,061 polytrauma patients presented with associated orbital injuries. Ocular injuries are not often given immediate concern as patients with life-threatening conditions need to be stabilized first. Undetected serious eye injuries might lead to a reduced or lost vision, which could result in severe limitations of quality of life. The results of our study speak in favor for early ophthalmological consultations and radiological imaging. Diagnostic and treatment of possible orbital injuries should be remembered in a polytrauma patient.
The bacterium Staphylococcus aureus is a notorious pathogen that causes dangerous and difficult-to-treat infections. This applies especially to methicillin-resistant S. aureus, better known as MRSA. MRSA infections were originally associated with healthcare settings as a consequence of clinical antibiotic therapy. However, in recent years MRSA infections have become more common among healthy individuals in the community. The community-associated (CA-)MRSA lineages are generally more aggressive than hospital-associated (HA-) lineages. Therefore, it is alarming that such CA-MRSA lineages are now emerging in hospitals. This raises the fundamental question of how CA-MRSA adapts to this new niche. Further, since the originally distinguishing features of CA- and HA-MRSA are losing discriminative value, it is important from a healthcare perspective to identify novel distinctive markers for early recognition and elimination of hospital-adapted CA-MRSA. In the present PhD research, these challenges were tackled with a ‘multi-omics’ approach focused on the USA300 lineage of MRSA, originally identified as CA, but now also causing hospital outbreaks. The results show that hospital-adapted USA300 isolates produce an altered spectrum of virulence factors, changed their metabolism, and exploit human immune cells as a protective environment against antibiotics. Importantly, hospital-adapted CA-MRSA strains can be recognized through distinctive patterns of gene expression and secreted virulence factors. Altogether, these observations show that the epidemic behaviour of MRSA is a multi-factorial trait, and they provide new insights into the missing links between epidemiology and pathophysiology of S. aureus. Moreover, they highlight the benefits of multi-omics technologies for protecting patients and frail individuals against the aggressive CA-MRSA.
We all know the experience of different demands on ourselves. As a parent, we want to be there for our children, and in pursuit of our career, we want to invest as much time as possible. If we are committed to both being a good parent and pursuing a career, it may be impossible to satisfy the demands stemming from both commitments. It is in such moments in which our, what I call, practical identities are conflicted that our will is in a state of volitional disunity. In this dissertation, I discuss how a person may best cope with volitional disunity.
I define practical identities in line with Christine M. Korsgaard as self-descriptions under which a person finds her life worth living and her actions worth undertaking; examples of such self-descriptions are being a parent, an employee, a hobbyist pianist, the friend of Charlotte, etc. Practical identities provide the person with ideals that form a decision-making framework for her deliberations about what to do. The standard analysis of volitional disunity, is that it causes a person to not know what to do as her identities, as guides, point her in conflicting, even opposite, directions. The solutions proposed in the literature always include, what I call, the Unification Ideal: a person has to prioritize her identities by deciding which is more important to her. By unifying her identities in this way, she constitutes who she is and wants to be thereby providing herself with a clear decision-making framework regarding the question of what to do.
In this dissertation however, I argue that a person does not need to overcome her volitional disunity through unification per se. In order to know what to do, a person could also explore the disunity that defines her will, which includes that she could accept the volitional disunity as hers. I base this Exploration Ideal on two assumptions about human nature: 1) we have inner responses to how we act and 2) we are opaque to ourselves. Since a person cannot always know in advance whether she will be happy with a commitment by turning her attention inwards, she can explore who she wants to be and who she can be through the bodily, psychological, and emotive responses she has to her actions. These responses, however, are not the ultimate authority. This authority stays with her practical identities in light of which she can evaluate these inner responses. Thus, a person exposed to volitional disunity should strive to explore this disunity, how she wants it to define her and whether it is constitutive of who she is (Exploration Ideal) instead of trying to overcome the disunity by striving for unification (Unification Ideal).
The importance of investments by emerging country multinationals to industrialised economies has risen continuously as illustrated by the growing number of Chinese merger and acquisitions (M&A) of German Mittelstand firms. This dissertation aims to analyse the effects of institutional distances on the M&A process. To this end, William Scott’s concept of institutions is newly operationalized to investigate institutional distances on the intra-firm, regional and international level. Through interviews with involved firms, intermediaries and key persons with dual backgrounds, the effects on different dimensions of the subsidiaries’ embeddedness as well as various mechanisms of institutional work during and after the M&A are evaluated.