Bulletin of the American Physical Society
2007 Joint New England Sections of the APS and AAPT Spring Meeting
Volume 52, Number 4
Friday–Saturday, April 20–21, 2007; Orono, Maine
Session A1: Statistical Physics & Applications |
Hide Abstracts |
Chair: Susan R. McKay, University of Maine Room: Bennett Hall 137 |
Friday, April 20, 2007 1:30PM - 2:30PM |
A1.00001: Imaging Nanoscale Protein Distributions in Live Cell Membranes with Fluorescence Photoactivation Localization Microscopy (FPALM) Invited Speaker: Resolution in light microscopy is limited by diffraction, yet structures exist on sub-diffraction length scales which are of great interest to the fields of biology and nanoscience. Recent developments in laser scanning microscopy, single molecule photophysics, and fluorescence spectroscopy are beginning to allow far-field optical methods to circumvent the diffraction barrier. Fluorescence photoactivation localization microscopy (FPALM) [1] images distributions of large numbers of (10$^4$ to 10$^6$) single photoactivatable fluorescent molecules, to generate a position map of those molecules with near-molecular ($\sim$20-30 nm) localization-based resolution. Molecules are initially trapped in an inactive (non-fluorescent) state, but illumination with brief pulses of 405 nm light photoactivates a stochastic subset of the inactive molecules. Photoactivated molecules are then illuminated by a second laser, and their fluorescence is imaged using a high-sensitivity camera at approximately five to ten frames per second. Molecules appear as diffraction-limited spots, which are then localized before photobleaching removes them from view. Additional molecules are photoactivated, imaged, and bleached, in a repetitive process that builds up data from thousands of molecules. Positions of localized molecules are plotted, weighted by their intensities, to form a super-resolution image of the sample. We present FPALM images of living and fixed fibroblast cells transfected with photoactivatable green fluorescent protein (PA-GFP), and of annealed crystalline and glass surfaces coated with PA-GFP. FPALM provides a means to image structures by far-field fluorescence microscopy with demonstrated resolution of $<$30 nm. \newline \newline [1] Hess, S. T., Girirajan, T. P. \& Mason, M. D. ``Ultra-high resolution imaging by fluorescence photoactivation localization microscopy.'' \textit{Biophys. J 91}, 4258-72 (2006). [Preview Abstract] |
Friday, April 20, 2007 2:30PM - 2:45PM |
A1.00002: REFRESHMENT BREAK
|
Friday, April 20, 2007 2:45PM - 3:45PM |
A1.00003: a-Synuclein interactions with model membranes Invited Speaker: a-Synuclein (a-S) has been identified as the major protein component of Lewy body deposits found in the brain tissue of persons suffering from Parkinson's Disease (PD). The interaction of a-S with membranes may be relevant both to its normal function as well as to the pathology of PD. While there have been numerous \textit{in vitro} studies of a-S binding to lipids, much of the existing literature regarding these interactions is contradictory. Fluorescence correlation spectroscopy (FCS) allows for rapid, equilibrium characterization of solutions of fluorescently labeled molecules and thus is a powerful technique for quantifying protein-lipid interactions. We use FCS to characterize the binding of a-S to large unilamellar vesicles (LUVs) as a function of lipid composition and phase, vesicle curvature, and charge density. [Preview Abstract] |
Friday, April 20, 2007 3:45PM - 4:45PM |
A1.00004: A Phase Space for Jamming Invited Speaker: In a remarkably diverse range of systems, the transition from a flowing, liquid state to a jammed, solid state is heralded by a dramatic slowing down of relaxations. Does an equilibrium phase transition underlie this glassy dynamics? To even begin to address this question, we need a statistical framework for describing systems out of thermal equilibrium. Can we construct a phase space for describing phase transitions in such non-equilibrium systems? In this talk, I will show how to construct a statistical ensemble for grain packings and use this statistical ensemble to construct a phase space for jamming and a field theory of two dimensional, zero-temperature, frictionless grain packings. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700