Research Experiences for Undergraduates
Summer 2013

Vanderbilt University
Physics & Astronomy

Research Projects: Biological Physics

Nonlinear Dynamics, Chemical Communication and Cell Migration
(Prof. Erin Rericha)
Our lab applies the ideas and tools from nonlinear physics and fluid dynamics to problems on the interface between physics and cell/ organismal biology. Our biophysics focus this summer will be on the influence of the microenvironment to direct cell migration. When the body is wounded or infected, chemical signals released at the site initiate signaling cascades which lead to the recruitment of white blood cells, such as neutrophils, from the blood stream to the damage site. Neutrophils migrate along increasing chemical concentrations of these signaling molecules in order to find the wound. The effective regulation of this process is vital to clearing infections and closing wounds without scarring. In addition, cancer cells show similar behaviors which promote cancer spreading. Understanding how cells undergo directed migration is a key part in developing more effective cancer treatments. Using a combination of microfluidics and optical tweezers we examine the coordination of these chemical gradients and the mechanical environment through which the cell migrates to determine the efficiency and path of migration. In conjunction with these experiments, we also measure the role of the intracellular fluid in force production as the cell migrates in three dimensional environments. Because understanding these problems require the development of new physics, students have the opportunity to perform experiments and numerical calculations on non-Newtonian fluid mechanics including: the motion of fluid through polymer networks of varying topology; synchronization in networks of excitable media; principles of storage and loss in surface interactions of non-Newtonian fluids; and the fluidization forces found in avalanches.

Multidisciplinary Biomedical Research
(Prof. John Wikswo)
Students will work in the development and application of micro- and nano-scale devices for instrumenting and controlling single biological cells and small cell populations. The cellular instrumentation project is working to develop and apply a new class of microscale devices that allow simultaneous recording of multiple signatures of a variety of cellular metabolic and signaling processes with sufficient bandwidth that will eventually be used to achieve stable, real-time, closed-loop external control of a single living cell. Such instrumented and controlled cells would help us answer the virtually innumerable sets of questions that will be raised by the explosion of genomic and proteomic information, and address issues as varied as using cells to identify and discriminate chemical and biological warfare agents by metabolic phenotype, the use of BioMEMS (BioMicroElectroMechanical Systems) devices to study molecular signaling associated with chemotaxis, cellular motility, angiogenesis, and metastasis; and the nature of signaling and metabolic activity during the immune response; and the associated how mechanical stimulation during cell culture alters cell morphology and physiology. Already in place are student-taught workshops in microfabrication and development of cellular instrumentation. These will be made available to the REU students enabling them to work at nano-scales that are not commonly available for hands on work by undergraduates.

Probing the Physical Forces that Drive Morphogenesis
(Prof. Shane Hutson)
Students will participate in interdisciplinary projects at the interface between physics and biology designed to probe the physical forces between cells. The action of these forces ultimately gives rise to the shape of an organism (morphogenesis). Students will investigate these forces during the embryonic development of the fruit fly. Students will have the opportunity to operate our custom laser-microsurgery workstation, which combines real-time 3D imaging via a laser-scanning confocal microscope with microsurgical capabilities via a pulsed Nd:YAG laser. By cutting the connections between individual cells in the embryo and following the subsequent mechanical response, one can solve the inverse problem to calculate the pre-incision forces between cells. Experimental projects include: quantitatively analyzing the morphogenetic dynamics occurring in specific episodes of fruit fly development, and testing hypotheses about the forces underlying these episodes by conducting microsurgical interventions. Computational projects include: automation of image-processing routines for feature extraction from 3D image sequences; modeling of native morphogenetic processes via finite element routines; and the use of finite element models for solving the inverse problem above. This project will team a physics REU student with a Vanderbilt biology student. The goal is for each student to see what interdisciplinary research is all about by collaborating with a peer from a different discipline.

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