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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Modely s racionálním očekáváním. / Models with rational expectation.

Bechyňák, Petr January 2007 (has links)
Práce popisuje vývoj konceptu mekonomického očekávání od extrapolativního, přes adaptivní až po racionální, včetně modelů, v nichž byla tato očekávání použita. V druhé části je odvozen a popsán model, využívající právě racionální očekávání. Tento agregovaný makroekonomický model je pak aplikován na prostředí ČR. Je zde testován i samotný předpoklad racionálního očekávání, což je myšlenka novější, než samotný model.
2

Generierung und Charakterisierung von Proteinderivaten zur gezielten Mineralisierung von DNA-Konstrukten

Gehlhar, Maria 14 June 2021 (has links)
Die Besonderheit der DNA-Nanotechnologie liegt in der Verwendung von DNA als Konstruktionsmaterial für die Herstellung von artifiziellen Strukturen im Nanometermaßstab (Seeman, 1982; Winfree et al., 1998). Diese DNA-Nanoobjekte, wie beispielsweise DNA-Nanoröhren, offerieren innovative und vielversprechende Anwendungsmöglichkeiten in verschiedenen Bereichen wie der Elektronik oder Medizin. Eine Herausforderung für die dauerhafte Verwendung von DNA-Nanoröhren stellt deren Stabilität dar. Einflussfaktoren wie die DNA-Nukleaseaktivitäten, die Ionenstärke und hohe Temperaturen können dabei eine langfristige Anwendung limitieren. Als ein Lösungsansatz für die Erhöhung der Beständigkeit wird eine gezielte Mineralisierung der DNA-Nanoröhren durch spezifische Fusionsproteine angestrebt. Ziel dieser Arbeit ist die dafür notwendige Herstellung und Charakterisierung der DNA-bindenden Fusionsproteine mit Mineralisierungsdomänen vorzustellen. Das umfasst das Auswählen geeigneter DNA-Bindungsproteine als Bestandteil der Fusionsproteine. In dieser Arbeit wurden die DNA-Bindungsproteine MutH und SBB aus Escherichia coli (E. coli) sowie Yku70p aus Saccharomyces cerevisiae (S. cerevisiae) aufgrund ihrer spezifischen Bindungseigenschaften dafür identifiziert. Damit können die Fusionsproteine sequenzspezifische oder -unspezifische Bindungen mit doppelsträngiger (engl. double stranded DNA, dsDNA) oder einzelsträngiger DNA (engl. single stranded DNA, ssDNA) eingehen. Es ist mittels Klonierung gelungen, verschiedene Fusionskonstrukte mit den genannten DNA-Bindungsproteinen zu generieren. Diese beinhalten ebenfalls das enhanced green fluorescent protein sowie den His6-Tag für den Expressionsnachweis und die Proteinreinigung. Weitere Varianten der Fusionskonstrukte bestehen zusätzlich aus der tobacco etch virus-Protease-Erkennungssequenz zur Entfernung des His6-Tags und der Domänen R5-Peptid (R5P) oder Poly-L-Arginin (PLR) für die Mineralisierung. Bestandteil dieser Arbeit sind Western-Blot-Analysen und mikroskopische Aufnahmen, welche die erfolgreiche heterologe Expression aller Fusionskonstrukte nachweisen. Aus den Ergebnissen der Expressions- und Löslichkeitsanalysen lässt sich schlussfolgern, dass insbesondere das Expressionslevel und die Synthese löslicher Proteine mit den Mineralisierungsdomänen eine Herausforderung darstellen. Ebenfalls in dieser Arbeit sind Versuche zur Optimierung mit verschiedenen Expressionsstämmen (E. coli und S. cerevisiae) und Expressionsparametern (Temperatur und Induktor-Konzentration) enthalten. Den Ergebnissen nach eignen sich besonders die Fusionsproteine MutH-EGFP-His6 und SSB-EGFP-His6 für die weiteren Experimente. Die Untersuchungen der DNA-Bindungseigenschaften erfolgten mittels Electrophoretic mobility shift assay (EMSA) und Rasterkraftmikroskopie (engl. atomic force microscopy, AFM). Diese Methoden mussten für jedes Fusionsprotein zuvor etabliert und optimiert werden. Zu Beginn stand das MutH-Fusionsprotein im Focus, wobei die durchgeführten EMSA-Untersuchungen die Spezifität zur GATC-Erkennungssequenz sowie zur dsDNA betrachteten. Die Charakterisierung mittels AFM diente als weitere Möglichkeit zur Analyse der DNA-Bindungseigenschaften. Zusätzlich kam in dieser Arbeit eine Variante des CRISPR/Cas9-Systems als Fusionsprotein für eine sequenzspezifische Adressierung von dsDNA zum Einsatz. Die EMSA- und AFM-Analysen deuteten dabei auf eine Interaktion von dem dCas9-Fusionsproteins und dsDNA hin. Weiterhin war das SSB-Fusionsprotein Bestandteil der Untersuchungen. Die Bindungsanalysen mittels EMSA zeigten, dass es bevorzugt mit ssDNA interagiert und nur eine geringe Affinität zu dsDNA vorliegt. Die Bindung zu ssDNA konnte ebenfalls erfolgreich anhand von AFM-Untersuchungen gezeigt werden. Zusammenfassend bestätigen die Ergebnisse die Funktionalität des MutH- und SSB-Fusionsproteins. Es konnten zudem erste Hinweise erbracht werden, die eine spezifische Bindung der Fusionsproteine an dsDNA oder ssDNA belegen. Mit dieser Arbeit ist es gelungen, Proteinderivate zu generieren und charakterisieren, wodurch eine entscheidende Grundlage für die gezielte Mineralisierung von DNA-Konstrukten geschaffen wurde.
3

DNA Mismatch Repair In Haemophilus Influenzae : Characterization Of MutH, L, S And Their Interaction

Joseph, Nimesh 12 1900 (has links) (PDF)
No description available.
4

Mutational Analysis of the MutH from Escherichia Coli: a Dissertation

Loh, Tamalette 29 September 2000 (has links)
DNA mismatch repair is one process in the preservation of genomic integrity. It has been found in Archeae, bacteria, plants, yeast and mammals. The mismatch repair system is highly conserved among species and allows the strand-specific elimination of base-base mispairs, chemical base modifications, as well as short insertion/deletion loops following DNA replication. The repair system also has important effects on homeologous recombination, contributing to the frequency of reciprocal exchanges. In humans, defects in the repair system have been found to be associated with tumorigenesis. In Escherichia coli, this pathway was originally called long patch repair before being renamed the methyl-directed mismatch repair system. It is unique in that it utilizes a DNA methylation pattern to discriminate between the parental DNA strand and the newly synthesized daughter DNA strand. The current model for the initiation of methyl-directed mismatch repair is that the mispaired bases are recognized and bound by the MutS protein with MutL as a helper protein for binding. MutL also assists the MutH protein to bind, thereby forming the completed initiation complex of MutS, MutL and MutH. In the presence of ATP, there is evidence for translocation ofthe complex along the DNA forming alpha loops. At a d(GATC) site the MutH protein binds and nicks the unmethylated daughter DNA strand 5' to the d(G) (by recognizing the N6-d(A) methylation of the parental DNA strand which it is unable to cut). This completes the initiation of the repair system and allows the hydrolysis and resynthesis of the daughter DNA strand. MutH is a monomer of 25.5 kD in solution and contains a latent Mg2+-dependent endonuclease activity. Unmethylated DNA is nicked without any discrimination on one of the two strands and fully methylated DNA is resistant to cleavage by MutH even though the protein is able to bind the d(GATC) site. The structure of MutH was recently solved and compared to a group of restriction endonucleases that share a structural common core domain with similarly placed catalytic residues. The MutH protein is comprised of two major domains that are able to pivot and rotate with respect to one another. The cleft between the two domains is large enough for double-strand DNA to bind. This research started with the determination of the MutH structure before it was known. After crystallizing the protein and collecting several heavy atom data sets, it was found that the electron density maps were too discontinuous to trace the structure of the protein. Following that work, site-directed mutagenesis was performed on several areas of MutH based on the similarity of MutH and PvuII structural models. The aims were to identify DNA binding residues (in two flexible loop regions), to determine if MutH has the same mechanism for DNA binding and catalysis as PvuII (MutH histidines 112 and 115), and to localize the residues responsible for MutH stimulation by MutL (MutH C-terminal tail region). An in-vivoscreen based on the mutator phenotype was used to select for functionally defective MutH mutants. These bacteria accumulate mutations at a greater frequency than wild-type and this was monitored by selection on plates with rifampicin. Three MutH mutants were identified from this screen (K48A, G49A, and Δ214). They were purified and assayed for total activity and binding ability. Four other mutants with wild-type phenotypic screen results were also chosen to confirm they were not involved in any MutH function (D47A, H112A, H115A, and Δ224). No DNA binding residues (such as D47A) were identified in the two flexible loop regions of MutH, although similar loops in PvuII are involved in DNA binding. The purified D47A MutH protein showed wild-type biochemical activity. Instead, the lysine residue (K48) in the first flexible loop was found to function in catalysis together with the three presumed catalytic amino acids (Asp70, Glu77, and Lys79). This purified MutH protein (K48A) had wild-type binding ability but no endonuclease activity without MutL. In the presence of MutL, the K48A protein had only a three-fold reduction in endonuclease activity. This research has shown that MutL stimulates the wild-type MutH activity by 1000-fold. The wild-type MutH stimulation by MutL for binding was only shown to be 16-fold. The G49A MutH mutant interferes with the proper functioning of the protein but is not informative about the mechanism of action. The binding ability of this mutant was the same as wild-type and the endonuclease activity was down 30-fold with a 10-fold stimulation by MutL. The extra methyl group of the alanine may cause slight structural changes in the lysine 48 side chain that slows catalysis. The two histidines (H112 and H115) in MutH that are in a similar position as the two histidines (H84 and H85) in PvuII (that signal for DNA binding and catalysis) were changed to alanines, but had wild-type activity both in-vivo and in-vitro. These results indicate that the MutH signal for DNA binding and catalysis remains unknown. The two deletion mutations (MutHΔ224 and MutHΔ214) in the C-terminal end of the protein, localized the MutL stimulation region to five amino acids (Ala220, Leu221, Leu222, Ala223, and Arg224). Mutant MutHΔ224 had wild-type MutL stimulation activity, while MutHΔ214 showed no MutL stimulation. Another deletion mutant, MutHΔ119, from another laboratory was shown to have wild-type MutL stimulation also. This leaves one (or more) of the remaining five residues as important for MutL stimulation.
5

Studies On DNA Mismatch Repair Nicking Endonucleases Of Haemophilus Influenzae And Neisseria Gonorrhoeae

Duppatla, Viswanadham 01 1900 (has links)
DNA mismatch repair ensures faithful transmission of genetic material from parents to progeny, which is required for the survival of the organism. The studies on E. coli MMR proteins have formed the basis for the study of the MMR system in eukaryotic organisms, because the functions of MMR proteins believed to be been conserved. In organisms that harbor MutH protein, it is known that MutH acts as a monomer which nicks the unmethylated daughter strand and is activated in a MutS-MutL- dependent manner. The cleavage specificity of MutH is very stringent. Till recently, it was not clear as to how MutH distinguishes hemimethylated DNA from fully or unmethylated DNA. The co-crystal structures of MutH-DNA complexes revealed that Y212, R184 and P185 were in close proximity to the methyl-adenine. Clustal-W sequence alignment of MutH with Sau3AI showed that Sau3AI has PCT residues instead of L183, R184, and P185. A triple mutant MutH-L183P-R184C-P185T was found to cleave both unmethylated and methylated DNA. The nicking endonuclease activity of the LRP→ PCT triple mutant was enhanced in the presence of Haemophilus influenzae MutL. The mutL gene of Neisseria gonorrhoeae was cloned and the gene product purified. It was shown that the homodimeric Neisseria gonorrhoeae MutL (NgoL) protein displays an endonuclease activity that incises covalently closed circular DNA in the presence of manganese or magnesium or calcium ions unlike human MutLα which shows endonuclease activity only in the presence of manganese. Further more the C-terminal domain of Neisseria gonorrhoeae MutL (NgoL-CTD) consisting of amino acids 460 to 658 also exhibits Mn2+ dependent endonuclease activity. Sedimentation velocity, sedimentation equilibrium and dynamic light scattering experiments show NgoL-CTD to be a dimer. By in vitro comparison of wild-type and a mutant NgoL-CTD protein, it was shown that the latter protein exhibits highly reduced endonuclease activity. Surface plasmon resonance spectroscopy was used to determine the kinetics of DNA binding by NgoL. The DNA binding was carried out in absence of metal ions. Interaction studies with NgoL with ssDNA in SPR spectroscopy revealed a KD value of 4.7 × 10–8 M. While the human MutLα endonuclease activity was shown to be stimulated by ATP, ATP inhibits NgoL endonuclease activity. By in vitro comparison of wild-type and a mutant NgoL-CTD protein, it was shown that the latter protein exhibits highly reduced endonuclease activity. NgoL ATPase activity was enhanced in the presence of DNA. The fact that NgoL ATPase activity is stimulated ~ 2.5-fold by dsDNA and ~ 2-fold by ssDNA is a further evidence for the interaction between NgoL and DNA. The results presented above show that NgoL harbors a nicking endonuclease activity which is present in the C-terminal domain. NgoL and NgoL-CTD are dimers in solution and DMHA(X)2E(X)4E motif present in the CTD is required for the nicking endonuclease activity. These results suggest that DNA mismatch repair mechanism in N. gonorrhoeae is different from that in E. coli. In the absence of MutH homolog, N. gonorrhoeae is able to repair the DNA by virtue of MutL nicking endonuclease activity.
6

Quantitative Modeling of DNA Systems

Crocker, Kyle A. January 2021 (has links)
No description available.
7

The Social Construction of Economic Man: The Genesis, Spread, Impact and Institutionalisation of Economic Ideas

Mackinnon, Lauchlan A. K. Unknown Date (has links)
The present thesis is concerned with the genesis, diffusion, impact and institutionalisation of economic ideas. Despite Keynes's oft-cited comments to the effect that 'the ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly understood'(Keynes 1936: 383), and the highly visible impact of economic ideas (for example Keynesian economics, Monetarism, or economic ideas regarding deregulation and antitrust issues) on the economic system, economists have done little to systematically explore the spread and impact of economic ideas. In fact, with only a few notable exceptions, the majority of scholarly work concerning the spread and impact of economic ideas has been developed outside of the economics literature, for example in the political institutionalist literature in the social sciences. The present thesis addresses the current lack of attention to the spread and impact of economic ideas by economists by drawing on the political institutionalist, sociological, and psychology of creativity literatures to develop a framework in which the genesis, spread, impact and institutionalisation of economic ideas may be understood. To articulate the dissemination and impact of economic ideas within economics, I consider as a case study the evolution of economists' conception of the economic agent - "homo oeconomicus." I argue that the intellectual milieu or paradigm of economics is 'socially constructed' in a specific sense, namely: (i) economic ideas are created or modified by particular individuals; (ii) economic ideas are disseminated (iii) certain economic ideas are accepted by economists and (iv) economic ideas become institutionalised into the paradigm or milieu of economics. Economic ideas are, of course, disseminated not only within economics to fellow economists, but are also disseminated externally to economic policy makers and business leaders who can - and often do - take economic ideas into account when formulating policy and building economic institutions. Important economic institutions are thereby socially constructed, in the general sense proposed by Berger and Luckmann (1966). But how exactly do economic ideas enter into this process of social construction of economic institutions? Drawing from and building on structure/agency theory (e.g. Berger and Luckmann 1966; Bourdieu 1977; Bhaskar 1979/1998, 1989; Bourdieu 1990; Lawson 1997, 2003) in the wider social sciences, I provide a framework for understanding how economic ideas enter into the process of social construction of economic institutions. Finally, I take up a methodological question: if economic ideas are disseminated, and if economic ideas have a real and constitutive impact on the economic system being modelled, does 'economic science' then accurately and objectively model an independently existing economic reality, unchanged by economic theory, or does economic theory have an interdependent and 'reflexive' relationship with economic reality, as economic reality co-exists with, is shaped by, and also shapes economic theory? I argue the latter, and consider the implications for evaluating in what sense economic science is, in fact, a science in the classical sense. The thesis makes original contributions to understanding the genesis of economic ideas in the psychological creative work processes of economists; understanding the ontological location of economic ideas in the economic system; articulating the social construction of economic ideas; and highlighting the importance of the spread of economic ideas to economic practice and economic methodology.
8

Johann Friedrich von Uffenbach. Sammler – Stifter – Wissenschaftler / Johann Friedrich von Uffenbach. Collector - Donor - Scientist

Meyerhöfer, Dietrich 28 January 2020 (has links)
No description available.

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