Thesis (Ph. D.)--University of Göteborg, 1994. / Published dissertation.

Universiẗat, Diss., 2003--Köln.

Organisms are comprised of many cells with multiple distinct cell types, each of which must be decided precisely to ensure proper formation of a functional organism. In C. elegans, the basic helix-loop helix transcription factor HLH-2 is required for the specification of the anchor cell, or AC. The AC arises from a group of four somatic gonad cells, all of which initially express HLH-2. Two of the four cells, which we call β cells, lose AC competence early and instead become ventral uterine precursor cells, or VUs. We call the remaining two cells α cells. One α cell becomes the AC, while the other becomes a VU. Which α cell becomes the AC is random—50% of the time one α cell becomes the AC, while the other 50% of the time the other α cell becomes the AC. The choice of which cell becomes the AC and which becomes the VU is called the AC/VU decision, and occurs through reciprocal signaling by LIN-12/Notch and its ligand LAG-2/DSL. At first, both α cells express similar levels of lin-12 and lag-2. As the AC/VU decision progresses, the AC expresses higher levels of lag-2, and the VU expresses higher levels of lin-12. By this time, HLH-2 is only present in the specified AC, while it is post-translationally degraded in VUs. The mechanism by which HLH-2 is degraded and the consequences of disrupting its degradation on AC specification are unknown. In this work, we studied the function and regulation of HLH-2 during two stages of somatic gonad development. First, we used long-term fluorescence microscopy to visualize HLH-2 over the course of somatic gonad development. We found that HLH-2 expression begins in the parents of the α and β cells a consistent amount of time after their birth, and that the parent cell that first expresses HLH-2 almost always gives rise to the α cell that becomes the VU, while the second cell to express HLH-2 gives rise to the AC. This led us to study the effect of a loss of hlh-2 activity in the α and β cells. We generated an α and β cell-specific hlh-2(0) allele using genome editing tools and found that LIN-12 protein is not present in the absence of hlh-2 activity. Based on this discovery, we conceived a model where HLH-2 expression biases the first-expressing cell towards the VU fate by endowing it with an edge in lin-12 activity. Next, we focused on restriction of HLH-2 to the AC. Typically, HLH-2 protein is degraded in VUs, which we hypothesized was a crucial step in restriction of the AC fate to a single cell. We found that in a lin-12(0) background, HLH-2 is stabilized in VUs even when the resulting cell does not become an AC, indicating that lin-12 directly promotes HLH-2 degradation. This led us to search for a lin-12-regulated factor that targets HLH-2 for degradation in VUs. We identified seven ubiquitin-related genes whose depletion resulted in stabilized HLH-2 in VUs, but surprisingly did not cause an AC/VU defect. We suspect that HLH-2 degradation in VUs is one of multiple negative regulatory mechanisms that ensure the robustness of the AC/VU decision. The following research contributes new insights into how stochastic cell fate decisions amplify noise to ensure a consistent and reproducible outcome.

Indiana University-Purdue University Indianapolis (IUPUI) / The basic Helix-Loop-Helix (bHLH) transcription factors Hand1 and Hand2 play critical roles in the development of multiple organ systems during embryogenesis. The dynamic expression patterns of these two factors within developing tissues obfuscates their respective unique and redundant organogenic functions. To define cell lineages potentially dependent upon Hand gene expression, we generated a mutant allele in which the coding region of Hand1 is replaced by Cre recombinase. Subsequent Cre-mediated activation of β-galactosidase or eYFP reporter alleles enabled lineage trace analyses that clearly define the fate of Hand1-expressing cells. Comparisons between Hand1 expression and Hand1-lineage greatly refine our understanding of its dynamic spatio-temporal expression domains and raise the possibility of novel Hand1 functions in structures not thought to be Hand1-dependent. To genetically examine functional overlap between Hand1 and Hand2, we conditionally deleted Hand2 from Hand1-expressing cells. Hand2 conditional knockout mice die midgestation and exhibit cardiovascular and limb defects. Moreover, Hand2 lineage-restricted deletion from the proepicardial organ results in defective epicardialization and failure to form coronary arteries. Together, these novel data demonstrate a hierarchal relationship whereby transient Hand1 expression within the septum transversum defines epicardial precursors that depend upon subsequent Hand2 function.

Die Tailspike Proteine (TSP) der Bakteriophagen P22, Sf6 und HK620 dienen der Erkennung von Kohlenhydratstrukturen auf ihren gram-negativen Wirtsbakterien und zeigen, von den ersten 110 Aminosäuren des N-Terminus abgesehen, keine Sequenzübereinstimmung. Mit Röntgenkristallstrukturanalyse konnte gezeigt werden, dass HK620TSP und Sf6TSP ebenfalls zu einer parallelen, rechtsgängigen beta-Helix falten, wie dies schon für P22TSP bekannt war. Die Kohlenhydratbindestelle ist bei Sf6TSP im Vergleich zu P22TSP zwischen die Untereinheiten verschoben. / The bacteriophages P22, Sf6 and HK620 need their tailspike proteins (TSP) for recognition of surface carbohydrates on their gram-negative host bacteria. Sequence identity is completely lacking in their C-terminal 500 to 600 amino acids. The three TSP have the same fold, an oligomeric parallel beta-helix, as shown by crystal structure analyses of HK620TSP and Sf6TSP. Compared with P22TSP, the carbohydrate binding site of Sf6TSP is located at the interface between two monomers and not on a single monomer.

Neutrophil degranulation involves a number of well-orchestrated structural and biochemical events. We have investigated the mechanism of intracellular signalling involved in neutrophil degranulation that was mediated by the high affinity leukotriene (LT)B[subscript 4] receptor, BLT1. The model systems used were consisted of Peripheral blood neutrophils as well as promyeloid PLB-985 cells, stably transfected with human BLT1 cDNA (PLB-BLT) or a substitution mutant (2L(304-305)/A) of the distal dileucine motif in helix VIII of BLT1, and differentiated into a neutrophil-like phenotype. The degranulation of these cells was measured in the presence and absence of factors that would affect the signaling pathway. The results show that Degranulation responses to LTB[subscript 4] were similar for differentiated PLB-BLT1 and neutrophils. However, the degranulation response of cells bearing the dileucine mutation in helix VIII of BLT1 was significantly reduced in response to LTB[subscript 4]. Pretreatment of differentiated PLB-BLT1 cells and neutrophils with Y-27632, a pharmacological inhibitor of p160-ROCK, the down-stream effector of the small GTPase RhoA, abrogated their degranulation in response to LTB[subscript 4]. The degranulation defect observed with the dileucine mutation was corrected by transient transfection of the cells bearing the mutation with a constitutively active form of RhoA. Taken together, our results suggest an essential role for the distal dileucine motif in helix VIII of BLT1 involving RhoA which allows normal neutrophil degranulation in response to LTB[subscript 4].

Innovation is widely recognised as essential to the modern economy. The term knowledgebased innovation system has been used to refer to innovation systems which recognise the importance of an economy’s knowledge base and the efficient interactions between important actors from the different sectors of society. Such interactions are thought to enable greater innovation by the system as a whole. Whilst it may not be possible to fully understand all the complex relationships involved within knowledge-based innovation systems, within the field of informetrics bibliometric methodologies have emerged that allows us to analyse some of the relationships that contribute to the innovation process. However, due to the limitations in traditional bibliometric sources it is important to investigate new potential sources of information. The web is one such source. This thesis documents an investigation into the potential of the web to provide information about knowledge-based innovation systems in the United Kingdom. Within this thesis the link analysis methodologies that have previously been successfully applied to investigations of the academic community (Thelwall, 2004a) are applied to organisations from different sections of society to determine whether link analysis of the web can provide a new source of information about knowledge-based innovation systems in the UK. This study makes the case that data may be collected ethically to provide information about the interconnections between web sites of various different sizes and from within different sectors of society, that there are significant differences in the linking practices of web sites within different sectors, and that reciprocal links provide a better indication of collaboration than uni-directional web links. Most importantly the study shows that the web provides new information about the relationships between organisations, rather than just a repetition of the same information from an alternative source. Whilst the study has shown that there is a lot of potential for the web as a source of information on knowledge-based innovation systems, the same richness that makes it such a potentially useful source makes applications of large scale studies very labour intensive.

There are many existing programs and initiatives in Uganda supporting small businesses, but tend to suffer from a number of weaknesses. In particular typically small businesses find it difficult to do research and development; commercialize their results in markets (innovation) as fast as they should. For micro, small & medium enterprises to be dully competitive in a competitive economic environment requires that they develop internal capabilities to effectively assimilate, use and adapt product and process technologies for their businesses to survive on an ongoing basis. To overcome this drawback, the concept of Business Incubation has been proposed. This concept has gained large interest in the research community. The key idea is to create and nurture new businesses for growth by providing services and infrastructure required by utilizing the external knowledge sources (open innovation) and triple-helix model which assist formation of business and industrial clusters. A business incubator is an organization that supports the creation and growth of new businesses by providing services and infrastructure that is required by the targeted clients. Given that most firms in developing countries start too small to compete especially in international markets, a pre-requisite to industrial development, governments and policy makers should give particular attention to the constraints and needs of MSMEs. This can be done by adopting a mix of policies and framework conditions to reduce on the obstacles that hamper technological innovation, collaboration and business growth. In particular is access to finance and enhancing technology and business capacity development through training, linkages and networks. This Licentiate thesis discusses and reviews the initiatives and programs aimed at supporting the development of MSMEs with a view to stimulate industrial development in Uganda. The main aim of this research is to examine the process of business incubation and explain the contribution of open innovation business incubators to entrepreneurs/ start-up firms within the broader context of developing entrepreneurship, promoting science, technology and innovation and creating employment. This research focuses on the roles and relationships of government, university and research institutions and the private sector as sources of knowledge for technological innovations. Literature review, theory understanding, and participatory methods including group discussions with questionnaires, meetings and interviews, were used to achieve the objectives. From the findings, it was revealed among MSMEs that due to their sizes, limited managerial and technological skills, and inadequate functional business support services have had adverse effects on their upgrading and growth. There was little linkage and follow up between industry and other public research sectors i.e. government agencies and higher institutions although there are quite a number of support institutions with poor coordination. The research analyzed a wide range of issues that are related to the desired structural transformation of the Ugandan economy towards industrialization process. Finally it will propose strategies for the most appropriate model for Uganda.

<p>An abstract of a thesis devoted to using helix-coil models to study unfolded states.\\</p><p>Research on polypeptide unfolded states has received much more attention in the last decade or so than it has in the past. Unfolded states are thought to be implicated in various</p><p>misfolding diseases and likely play crucial roles in protein folding equilibria and folding rates. Structural characterization of unfolded states has proven to be</p><p>much more difficult than the now well established practice of determining the structures of folded proteins. This is largely because many core assumptions underlying</p><p>folded structure determination methods are invalid for unfolded states. This has led to a dearth of knowledge concerning the nature of unfolded state conformational</p><p>distributions. While many aspects of unfolded state structure are not well known, there does exist a significant body of work stretching back half a century that</p><p>has been focused on structural characterization of marginally stable polypeptide systems. This body of work represents an extensive collection of experimental</p><p>data and biophysical models associated with describing helix-coil equilibria in polypeptide systems. Much of the work on unfolded states in the last decade has not been devoted</p><p>specifically to the improvement of our understanding of helix-coil equilibria, which arguably is the most well characterized of the various conformational equilibria</p><p>that likely contribute to unfolded state conformational distributions. This thesis seeks to provide a deeper investigation of helix-coil equilibria using modern</p><p>statistical data analysis and biophysical modeling techniques. The studies contained within seek to provide deeper insights and new perspectives on what we presumably</p><p>know very well about protein unfolded states. \\</p><p>Chapter 1 gives an overview of recent and historical work on studying protein unfolded states. The study of helix-coil equilibria is placed in the context</p><p>of the general field of unfolded state research and the basics of helix-coil models are introduced.\\</p><p>Chapter 2 introduces the newest incarnation of a sophisticated helix-coil model. State of the art modern statistical techniques are employed to estimate the energies</p><p>of various physical interactions that serve to influence helix-coil equilibria. A new Bayesian model selection approach is utilized to test many long-standing </p><p>hypotheses concerning the physical nature of the helix-coil transition. Some assumptions made in previous models are shown to be invalid and the new model </p><p>exhibits greatly improved predictive performance relative to its predecessor. \\</p><p>Chapter 3 introduces a new statistical model that can be used to interpret amide exchange measurements. As amide exchange can serve as a probe for residue-specific</p><p>properties of helix-coil ensembles, the new model provides a novel and robust method to use these types of measurements to characterize helix-coil ensembles experimentally</p><p>and test the position-specific predictions of helix-coil models. The statistical model is shown to perform exceedingly better than the most commonly used </p><p>method for interpreting amide exchange data. The estimates of the model obtained from amide exchange measurements on an example helical peptide </p><p>also show a remarkable consistency with the predictions of the helix-coil model. \\</p><p>Chapter 4 involves a study of helix-coil ensembles through the enumeration of helix-coil configurations. Aside from providing new insights into helix-coil ensembles,</p><p>this chapter also introduces a new method by which helix-coil models can be extended to calculate new types of observables. Future work on this approach could potentially</p><p>allow helix-coil models to move into use domains that were previously inaccessible and reserved for other types of unfolded state models that were introduced in chapter 1.</p> / Dissertation

Notre étude a pour objet de déterminer l’impact engendré par les infrastructures technologiques sur l’innovation et la croissance économique dans les pays de l’Organisation de Coopération et de Développement Economiques (OCDE). Nous allons nous inspirer de la théorie « Quadruple Helix of Innovation » (QH) pour construire un modèle théorique de croissance économique afin d’évaluer le rôle joué par un ensemble d’infrastructures technologiques, en présence des systèmes ouverts d’innovation et du « Mode 3 » de production des connaissances. Nous avons choisi la récente théorie QH au sein des Systèmes Nationaux d’Innovation (SNI) car elle décrit une nouvelle réalité économique où l’innovation est considérée comme le résultat de la co-création entre les entreprises, les citoyens, les universités et le gouvernement, dans un contexte caractérisé par l'existence de partenariats, de réseaux de collaboration et de relations symbiotiques. Un modèle théorique de croissance économique axé sur la R&D et avec des dépenses publiques productives sera élaboré afin de démontrer l’importance de l’existence des infrastructures technologiques et il sera possible d’apprécier les effets des dépenses publiques productives à travers une étude de « dynamique transitoire » et une analyse empirique fondée sur la nouvelle base de données CANA (2011). / Our study has the aim of defining the impact generated by the technological infrastructure on innovation and economic growth in the countries of the Organization for Economic Cooperation and Development (OECD). We will draw inspiration from the "Quadruple Helix of Innovation" theory (QH) in order to construct a theoretical model of economic growth that will assess the role played by a set of technological infrastructures belonging to different "innovation ecosystems", in the presence of innovation open systems and the "mode 3" of knowledge production. We chose the recent QH theory on National Innovation Systems (NIS) as it describes a new economic reality where innovation is seen as the result of co-creation between businesses, citizens, universities and government, in a context characterized by the existence of partnerships, networks of collaboration and symbiotic relationships. A theoretical model of economic growth based on R & D and on productive public spending will be developed to demonstrate the importance of the existence of technological infrastructure in promoting innovation, and ultimately its contribution to economic growth. This will make it possible to evaluate the effects of productive public spending through a study of "transitional dynamics" and an empirical analysis based on the new database CANA (2011).