BACTERIAL CHEMOTAXIS

Ford

Roseanne Ford is the first and presently only female Professor of Chemical and Biochemical Engineering at UVA. Dr. Ford obtained her B.S. in Chemical Engineering at the University of Delaware and continued her education at the University of Pennsylvania to receive M.S. in Chemical Engineering. She later finished her Postdoctoral Fellowship studying “Bacterial Chemotaxis – Cell Flux Model, Parameter Measurement, Population Dynamics, and Genetic Manipulation” obtaining her Ph.D. in 1989 in Chemical and Biochemical Engineering at the University of Pennsylvania. Afterwards, she became a Professor at the University of Virginia and has produced many publications of chemotaxis in scholarly journals such as Journal of the American Chemical Society

Presentation

On Tuesday, February 18, Dr. Rosanne Ford gave her presentation on bacterial chemotaxis in Wilsdorf Hall in the School of Engineering, Department of Materials Science and Engineering and the Center for Nanoscopic Materials Design. She began her lecture with a brief introduction on how bacteria can remediate oil spills in bodies of water by converting hydrocarbons and oxygen into less noxious components like carbon dioxide and water. She illustrated this bioremediation process as safe and natural, attributing the bacteria attraction to chemicals as chemotaxis, a bacterium’s affinity to direct their entire movement towards a chemical gradient. Dr. Ford clarified the components responsible for this mechanism by explaining the inner machinery of bacterial motor locomotion. When a bacterium encounters an attractive chemical in its environment, the molecules stimulate extracellular receptors in its membrane. These intermediary transducers signal many tiny flagella to spin and propel the cell toward the higher concentration. To ensure the greatest chances for survival, specific cellular appetites have developed alongside clear methods to detect and pursue their source.

trajectoryDr. Ford studied bacterial movement under a 3D-tracking microscope, taking a picture every twelfth of a second and viewing the images in succession. In patterns of stimulus and response, the bacteria swim in one linear vector at a time. Red dots in her maps indicate when the bacterium has changed direction to follow signals in its immediate environment. At a larger scale, Dr. Ford presented wonderful patterns of mass bacterial migration extending from a single origin in a petri dish, and each example revealed a unique pattern of systematic exploration and colonization. Chemotaxis has curious potential for scientific artwork and pattern mapping. Dr. Ford collaborated with a local musician to create an algorithm that linked specific movements to certain sounds, transducing chemotaxic mechanical movement into sound production and music. The most practical implications of her studies explore the efficiencies of bacterial chemotaxis as corrective remediation for oil spills that have seeped deep into the ground and threaten the water table. By understanding the relationships between the chemical gradient, the mechanical response, and the visual measurements, scientists are able to read this multidimensional language and predict how much time, bacteria, and money would be required for a full scale remediation project on a poisoned landscape.

Response

The aspartate receptor is the primary transduction agent that links the outside world to the inner workings of the cell. Located within the membrane, the receptor creates a binding opportunity for specific ligands outside the cell, and these encounters signal conformational changes within the cell, such as protein production and release. In the language of these chemosensory mechanisms, a build up of a protein called “CheY” will cause the locomotor complex of bacteria to move in a different direction. Depending on the concentration of an attractive chemical cue, it will influence the rotation of the flagella. Since chemical cues can be transduced into mechanical energy, there can be widespread implications for the analysis of human behavior and their physical attractions. For instance, studying this paradigm could inform our understanding of human responses to chemical stimulus and the extent a body can will itself to obtain it. These micro-scale models of addiction, attraction, and motivation can potentially link the behaviors of individuals to those of entire populations.

As the systems of migration are better mapped, chemotactic bacterial growth holds potential as an art of distinct spatial-temporal evolutions. If factors such as “initial cell density, nutrient concentration, and chemotaxis strength” are known, then the type of emerging paths can be predicted through a mathematical algorithm. Perhaps bacterial chemotaxis can be transduced into visual and acoustic expressions by manipulating the variables that affect its proliferation, illustrating biological beauty through methodical means. As a result, researchers and their audience can obtain an representations of bacterial growth in a language that bridges the divide between observation and manipulation.

More Information

Spatial Patterns Formed by Chemotactic Bacteria Escherichia Coli

URBAN METABOLISM

JorgJorg Sieweke is an Assistant Professor of Landscape Architecture at the UVA School of Architecture. He received a Diplom-Ingenieur in landscape architecture from the University of Essen and an M.A. in Architecture with a concentration in urban design from Berlin’s Kunsthochschule. Through his dual degrees, he is a licensed landscape architect and urban designer in Berlin and previously practiced with Stefan Tischer and Topotek1. He is director of ‘_Scapes’ urban design, his firm based in Berlin. As an Academic, Professor Sieweke joined the UVA faculty in 2009 from Technische Universität School of Architecture in Berlin. He is a recipient of numerous awards in design projects and teaching as well as the co-author of Energy Atlas : IBA-Hamburg. He is also involved in public service and consulting, and is an advisory board member of “UrbanbyNature,” the 2014 Architecture Biennale project from Netherlands in Rotterdam. To further his interest in implications of modernizations on urban landscapes, he is director of ParadoXcity, a design-based research initiative focused on understanding the swampy grounds of DeltaCities such as Venice, New Orleans, Baltimore and Hamburg in hopes of inventing a sustainable infrastructure. Professor Sieweke focuses on concept, strategy, theory and tactic to inform design of urban landscape as a critical practice.

Presentation

On Tuesday, February 18, Professor Sieweke gave a presentation titled “Urban Metabolism” in conjunction with Professor Ford’s presentation on “Chemotaxis” as part of the week’s “Taxis” theme. Urban metabolism is explained as ”the physiological process [transportation and transformation of matter and energy] in anthropogenic ecological systems.” Invented by Paul Crutzen, a Nobel prizewinning atmospheric chemist, the word “anthropocene” defines ‘the era of the human being’ in which humanity is affecting the earth at the scale of its planetary ecology. To explain these theories in depth, Professor Sieweke presented problems and solutions that have arisen in the metamorphosis of urbanism. The main concerns of our current society are the often ignored “Limits of Growth” that balance environmental degradation and overpopulation. Landscape architects combat the problems of disappearing natural ecologies in a quickly developing globalized world. He warned the myopic complications that accompany the common notion of cities as closed systems, as depicted by the illustration below by Cedric Price.

City as Egg

He highlighted the concept of ‘hinterland’ as a necessary critique of contemporary planning. Hinterland is defined as the “territories and compartments of the environment outside the borders of an urban system, which this urban system necessitates for the import and export of goods”. Incorporating the idea of hinterlands and employing the Netzstadt method (a scientific approach to urban planning), planners analyze material flow analysis to visualize the division of human activities and to quantify the resources that enter and leave the assumed system boundary. Hinterlands describe those spaces outside the concerns of the urban condition, but increasingly those regions are cities themselves, or exploited for its benefit. When one system’s outside becomes another’s inside, there must be more efficient considerations in place for a successful planetary metabolism. When the concentrated metropolis depends of an excess of resources in neighboring landscapes, the boundaries of the complete urban condition must be re-conceptualized as a more holistic system.

Netzstadt

Professor Sieweke posed a question: if the entire world is turning urban, can we continue to rely on hinterland? His solution is to think of the geosphere with an inclusive concept of what before, has been the “other”. The L.A. River is a quintessential example of a quasi-natural environment in which the recycled sewage treatment water is not fenced away “outside” the city, but is channeled into the river’s domesticated cement banks. Years of use have allowed the highly engineered condition to relax into a natural order, where animals and plants now take part in a complex and ruinous infrastructural landscape. In relation to this concept, he emphasized the importance of addressing the issues of urbanism through societal and cultural momentum instead of policy. He showed a clip of a popular film, Drive that showed a romanticized overgrowth of L.A. River’s extents, through which public audiences can digest the inclusive concept that serve as convincing alternatives to contemporary boundaries.

BetterQ_LA_River_DriveIn conclusion, he proposed that we must solve the urban problems in order to solve the global problems.

Response

Taxis, broadly defined as a movement in response to a stimulus, is a fundamental concept for collaboration and transduction of signals. The progression of Professor Sieweke’s presentation highlighted the failures of technological fixes for the issues of urbanism. Waiting on the release of miraculous devices and inventors often leads to a deterministic cycle of temporary solutions and oversized complications. Individual transduction of cultural acceptance and collaboration of differing expertise may be more effective and provide a long-lasting solution for vast issues of urbanism. In the successful renovation of past systems of thought and consideration of more sustainable practices, whole communities could help imagine small improvements to the control of greater networks. The current urban environment is complex and is shared between many societies. The concerns of climate change and imminent shortage of resources must not be tackled by engineers alone, but in conjunction with design and its public.  An inviting environment, honestly designed for people and larger ecological services will lead to more organic community efforts to accept and maintain the responsibilities that follow global urbanization.

In this way, mass media and social media play a huge role as a medium between the taxis of human interfaces and activism at a planetary scale. Through artistic expression, real events and alternative perspectives can be communicated and shared across space and time boundaries. A non-fictional or even a fictional film can convince an audience through logical arguments using its visual and audible evidence. The role of media in current society can transmit information as signals that inspire our practical imaginations.

MAPPING CONNECTIONS

Project Lab: Preliminary Sketches

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Thematic Connections

Taxis_Map_3

Urban metabolism is connected to chemotaxis through common themes in the middle. Natural resources lead to energy, which is then mediated by transducers that convert this energy into forms of physical movement or progress in society. Hinterland is labeled as movement/progress because recognition that the hinterland is in fact part of society, not separate it, is imperative for a self-sustainable society in the current model of urbanism to create a stable and cyclic energy flow, the quintessence of a maintainable city. Furthermore, parallels can be drawn between chemotaxis and urban metabolism from an artistic perspective to represent the “design” category. Bacterial chemotaxic growth can develop from a manipulation of variables affecting its propagation, whereas the design of urban cities can lead to the development of a blueprint for sustainability.

Report by SunHye Park and William Park.