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Picornaviridae Zum Gestalten von Modell- und Visualisierungskonzepten in der Virologie
Abstract
Die Publikation setzt sich mit der Darstellbarkeit von Virusstrukturen unter Berücksichtigung ihres geometrischen Ursprungs am Beispiel der Familie der Picornaviren (Picornaviridae) auseinander. Sie stellt damit eine Schnittstelle zwischen Wissenschaft und Gestaltung dar und stellt das Potenzial gestalterischer Prozesse innerhalb interdisziplinärer Forschungsansätze heraus.In diesem Kontext stehen modellbezogene Lehr- und Lern-prozesse sowie die Auseinandersetzung mit den Schwierigkeiten und Grenzen der seit den 1960er-Jahren etablierten Modelle im Fokus. Dabei werden auch Fragen zur Kongruenz in Text und Bild sowie zur immanenten Verknüpfung von Theorie- und Modellbildungsstrukturen gestellt und beantwortet:
Welche zentrale Rolle spielten theoretische Modellkonzepte tatsächlich in Bezug auf die Thesenentwicklung früher Pioniere der Virusforschung? Was haben Buckminster Fullers Tensegrity und geodätische Kuppeln mit Virusstrukturen gemein?
Das entwickelte und in der Publikation dargestellte Konzept stellt sich der Vielzahl isolierter Visualisierungskonzepte und funktioniert als erweitertes, verknüpfendes und umfassendes Modellkonzept. Es bietet die Möglichkeit, als literaturübergreifender Verständnisschlüssel genutzt zu werden; dabei kann es Lehre und Forschung didaktische Mittel an die Hand geben, welche die Förderung einer allgemeinen Modellkompetenz unterstützen.
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The P21 Framework for 21st Century Learning identifies collaboration as a key educational outcome as it prepares students for the real world problem solving and enhance their prospects for employment. Therefore, group assessments are becoming a commonplace in higher education, mainly to promote collaborative working environment and peer learning amongst students. In addition, group assessments are considered as an effective assessment strategy to manage large classes as it reduces the marking burden on academics. Despite the benefits, students resent group work particularly when a common group mark is awarded when there is a varying level of inputs from the members of the group. Especially, non- engaging students could possibly attain good grades without contributing to the group work or with minimal contribution. This problem of “free riders” disadvantages and discourages engaging students. There is a plethora of peer assessment methods used by academics to assess group works. However, there is a dearth of studies which explores why a particular method is preferred and the difference it makes on the final grades of students. Therefore, this paper explores different methods of peer assessments by reviewing recent literature and expands into comparing the final grades derived from two different methods of peer assessments adopted in the same module to study the end results. Finally, the correlation between the final individual grades and the peer marks given was unpacked which allows academics to make an informed decision.
Humans are fundamentally designers – humans create artifacts, shelters, communities, and landscapes. Design is a complicated process and involves conceiving, representing, and executing constructions across a wide range of scales. Various methods and approaches to design have been theorized over the last several decades resulting in a wide range of design process diagrams and strategies. The task outlined here was to develop a tool to help structure the ongoing decision-making that is part of any design process, to present a comprehensive range of topics that designers should consider as they evolve a scheme. To this end we are introducing the Diagram as a working tool that frames a broad range of spatial, ecological, cultural, and material factors; it is designed to play a key role as a teaching tool primarily within design studios.
It is difficult to think of science without models: they are part of our surrounding material culture. In fact, material models are a key part of modern research within different fields of science. Especially in university education is a great demand of assessing material models in both digital and physical materiality. Modeling competence has a major impact on the level of understanding models and on the ability to push forward further research, especially regarding the highly dynamic processes in the context of model creation, hypothesising, questioning and recreation. The present paper focus on the phenomenon of missing modeling competence and illustrates possible practice-based solution approaches out of the perspective of a designer who is developing educational model concepts.
Modelling is the essence of thinking and working scientifically. But how do secondary students view science models? Usually as toys or miniatures of real-life objects with few students actually understanding why scientists use multiple models to explain concepts. A conceptual typology of models is presented and explained to help teachers select models that are appropriate to the conceptual ability of their students. The article concludes by recommending that teachers model scientific modelling to their students, encourage the use of multiple models in science lessons, progressively introduce sophisticated models, systematically present in-class models using the Focus, Action and Reflection (FAR) guide and socially negotiate all model meanings.
In the mid 1950s, Francis Crick and James Watson attempted to explain the structure of spherical viruses. They hypothesized that spherical viruses consist of 60 identical equivalently situated subunits. Such an arrangement has icosahedral symmetry. Subsequent biophysical and electron micrographic data suggested that many viruses had >60 subunits. Drawing inspiration from architecture, Donald Caspar and Aaron Klug discovered a solution to the problem - they proposed that spherical viruses were structured like miniature geodesic domes.
The three-dimensional structure of human rhinovirus 14 has a deep surface depression or "canyon" encircling each of the twelve 5-fold vertices. The canyon's surface is inaccessible to the broad antigen binding region of antibodies, permitting conservation of residues that might be required for host cell receptor recognition without danger of attack by the host's immune system. In contrast, the exposed surface features, where neutralizing antibodies are known to bind, change rapidly under pressure from the host's immune system. It was, therefore, hypothesized that this depression was the site of receptor attachment. Similar, but smaller, depressions had been observed previously on both the hemagglutinin and neuraminidase spikes of influenza virus. These have also been shown to be the site of host cell interaction. Although support for the canyon hypothesis was only circumstantial in the first place, there are now extensive confirmatory data. These include site-specific mutations of residues in the canyon and conformational changes induced in the canyon by the binding of small organic molecules, all of which alter receptor attachment. The strategy used in human rhinovirus 14 to protect the viral receptor attachment site from immune surveillance may be utilized not only in other picornaviruses but also in many other types of viruses including human immunodeficiency virus.
A schematic drawing summarizes the overall features of a structure in a quickly graspable and relatively memorable form. It follows that there are two crucial and nontrivial tasks of a schematic drawing. The first is to portray the overall organization of the structure rather than a collection of details; for example, one should try to draw a β- sheet rather than drawing β-strands. The second major task is to communicate accurate three-dimensional information, by utilizing all available monocular depth cues and, where possible, by mimicking the appearance of a binocular image. There are many different but related types of schematics, for example, for myoglobin, carbonic anhydrase, thioredoxin, immunoglobulin, PGM, and tRNA. Along with the specific methods explained, it could also add or substitute conventions from some of those other representations if they were especially suitable for showing the features of a given structure. For example, in showing large multisubunit structures it is helpful to simplify further to cylindrical helices and entire β-sheets or β-barrels.
Purposeful switching among different conformational states exerts self-control in the construction and action of protein assemblies. Quasi-equivalence, conceived to explain icosahedral virus structure, arises by differentiation of identical protein subunits into different conformations that conserve essential bonding specificity. Mechanical models designed to represent the energy distribution in the structure, rather than just the arrangement of matter, are used to explore flexibility and self-controlled movements in virus particles. Information about the assembly of bacterial flagella, actin, tobacco mosaic virus and the T4 bacteriophage tail structure show that assembly can be controlled by switching the subunits from an inactive, unsociable form to an active, associable form. Energy to drive this change is provided by the intersubunit bonding in the growing structure; this self-control of assembly by conformational switching is called "autostery", by homology with allostery. A mechanical model of the contractile T4 tail sheath has been constructed to demonstrate how self-controlled activation of a latent bonding potential can drive a purposeful movement. The gradient of quasi-equivalent conformations modelled in the contracting tail sheath has suggested a workable mechanism for self-determination of tail tube length. Concerted action by assemblies of identical proteins may often depend on individually differentiated movements.
Excerpt
THE FUNCTIONAL ORGANIZATION OF VIRUS PARTICLES
There are two key facts about viruses from which all consideration of their structure and functional organization must proceed. The first is that the essential infective agent of all viruses is a high molecular weight nucleic acid component— either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). Second, the nucleic acid molecule is contained in a protective package which serves to transmit this infectious agent in a functionally intact state through space and time to a susceptible host.
The virus nucleic acid has the capacity of redirecting the synthetic machinery of its host cell to the production of more virus. It is becoming increasingly clear that this control over the cell metabolism can be exerted at a number of different stages of normal biosynthesis. The DNA of large bacteriophages, for example, may pertinently be regarded as a transmissible piece of bacterial chromosome (Luria, 1959). In...
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