Bulletin of the American Physical Society
80th Annual Meeting of the APS Southeastern Section
Volume 58, Number 17
Wednesday–Saturday, November 20–23, 2013; Bowling Green, Kentucky
Session FB: Biophysics and Medical Physics |
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Chair: Xujing Wang, University of Alabama at Birmingham Room: 3/4 |
Friday, November 22, 2013 11:00AM - 11:12AM |
FB.00001: Mismatch repair protein mobility in human cancer cells Keith Bonin, Justin Sigley, Martin Guthold Here we plan to report on the mobility of the mismatch repair protein msh2 in cells from a cell line that has normal, immortal, and tumorigenic cells. Additionally we have measured the mobility of the protein in metastatic MDA-MB-231 cells. Specifically, we plan to report on the diffusion coefficients of msh2 as measured using Raster Image Correlation Spectroscopy, a single molecule technique that takes advantage of the natural scanning nature of confocal microscopes. Results will be reported on all four cell types, with separate measurements for both cytoplasmic and nuclear cell regions. [Preview Abstract] |
Friday, November 22, 2013 11:12AM - 11:24AM |
FB.00002: Finite Element Modeling of Heat Shock-Induced Mechanical Failure in Drosophila Amnioserosa W. Tyler McCleery, Sarah M. Crews, David N. Mashburn, Jim Veldhuis, G. Wayne Brodland, M. Shane Hutson Embryonic development is a complex process that is both regulated genetically and constrained mechanically. Normal development can be disturbed by environmental perturbations, leading to a range of developmental defects. For example, application of heat shock to fruit fly (\textit{Drosophila melanogaster}) embryos leads to the much later opening of holes in the dorsal region of a specific epithelial tissue, the amnioserosa. Embryos exhibiting such holes fail to appropriately complete subsequent developmental processes like germ band retraction and dorsal closure. We hypothesize that holes appear in the dorsal amnioserosa, as opposed to other epithelial tissues, due to the localized concentration of tensile stress. To test this hypothesis, we are developing cell-level finite element models of early Drosophila embryos to analyze the morphogenetic stress fields. We will also use these models to test whether holes in the amnioserosa are sufficient to cause subsequent failures in germ band retraction. [Preview Abstract] |
Friday, November 22, 2013 11:24AM - 11:36AM |
FB.00003: Manipulating morphogenesis with light using photoactivatable Rac1 Monica Lacy, Shane Hutson, Andrea Page-McCaw, Kimberly LaFever One of the major focuses in current Drosophila studies is the morphogenetic process of germ band retraction, which involves two embryonic tissues--the germ band and the amnioserosa--moving in tandem. A challenge of particular interest for biophysicists is defining the specific roles of the proteins that regulate cell motility in these tissues, as well as quantifying the forces exerted as a result of their activity. Among the proteins active in the embryo is the Rho GTPase Rac1, which regulates the formation of lamellipodia at cell edges. My research uses new tools to investigate the role of Rac1 in GBR, with the eventual goal of quantifying the forces involved. Existing work suggests that the crawling of the amnioserosa over the caudal end of the germ band, aided by lamellipodia, is instrumental in the onset of GBR. Using photoactivatable forms of Rac1 incorporated into fly stocks and targeted laser illumination, I will directly control spatial and temporal patterns of Rac1 activation in the amnioserosa to test the hypothesis that increasing and decreasing Rac1 activity in the amnioserosa will affect its crawling over the germ band, and subsequently the process of GBR. This work will explore the possibilities of photoactivatable proteins in biophysical research and add to the body of knowledge on the motions and forces involved in Drosophila morphogenesis. [Preview Abstract] |
Friday, November 22, 2013 11:36AM - 11:48AM |
FB.00004: Stress field mapping in the amnioserosa of \textit{Drosophila} embryos using laser microsurgery Sarah M. Crews, W. Tyler McCleery, M. Shane Hutson Embryonic development in \textit{Drosophila} is a complex process involving coordinated movements of mechanically interacting tissues. Perturbing this system with a transient heat shock can result in a number of developmental defects. In particular, a heat shock applied at gastrulation can lead to apparent recovery, but then subsequent failure 5-6 hours later during germ band retraction. The amnioserosa, a single layered epithelial tissue, is known to be mechanically essential for the completion of germ band retraction. Heat shock at gastrulation can induce the later opening of holes in the amnioserosa, which can lead to a failure in germ band retraction. These holes could be caused by a combination of weakness in the amnioserosa or increased mechanical stress at the site where holes open. Here, we use laser hole drilling to map the stress field of the amnioserosa around the times of hole openings to inform the cause of this mechanical failure. [Preview Abstract] |
Friday, November 22, 2013 11:48AM - 12:00PM |
FB.00005: Computer Simulations for Understanding Dose Enhancement Through Microdosimetry Nicole Ackerman Dose enhanced radiotherapy uses high atomic number materials, such as iodine and gold, to increase local dose from radiation, such as X-rays. The efficacy of this technique has been demonstrated in many systems, but results have not been consistent. I will present a detailed simulation method for measuring dose enhancement from physical models. Using Geant4, I am able to explore the underlying physics, such the role of low energy electrons and differences in beam energy. I combine Geant4 with a double strand break model, which predicts additional enhancement for low beam energies. This work furthers our understanding of how to measure and simulate dose enhancement, working toward optimized drugs for clinical treatment. [Preview Abstract] |
Friday, November 22, 2013 12:00PM - 12:12PM |
FB.00006: A Study of Cultural Modifications and Taphonomic Alterations on Prehistoric Human Skeletal Remains from Crystal Onyx Cave (15Bn20), Barren County, Kentucky Using the Large Chamber Scanning Electron Microscope Julie Scott, Darlene Applegate, Edward Kintzel Crystal Onyx Cave is a pit cave on Prewitts Knob in Barren County that was used prehistorically (ca. 1100-800 BC) as an ossuary. Archaeologists collected human bones from the cave in the 1980s, and since 1999 faculty and students at Western Kentucky University have been analyzing the remains. Over 2,800 highly fragmented bone specimens represent over thirty commingled male and female adults and subadults. This research focused on analysis of cut marks and elemental deposits on over 100 bone specimens using the Large Chamber Scanning Electron Microscope (LC-SEM) at WKU. Nondestructive testing of the remains was made possible using the variable pressure mode with back-scattered electrons for topographical analysis and use of energy dispersive spectroscopy for elemental analysis. The results confirm the practice of mortuary treatment involving defleshing and disarticulation at the Early Woodland site, as well as post-depositional accumulation of manganese in the cave environment. [Preview Abstract] |
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