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Saturday, November 9, 2019 at 8:00am to 5:00pm
Physical Sciences Building, 120
245 East Avenue
Samuel Hess, Professor of Physics, Physics and Astronomy, The University of Maine
Research Highlights from Cornell’s Field of Biophysics
"Super-Resolution Microscopy: Technological Advances Coupled to Biological Insights"
Localization microscopy circumvents the diffraction limit by identifying and measuring the positions of numerous subsets of individual fluorescent molecules, ultimately producing an image whose resolution depends on the uncertainty and density of localization. Now that the diffraction barrier has been broken, what defines the best possible resolution that can be obtained? Photophysical studies coupled with a theoretical framework reveal that there is an optimal resolution for a given fluorescent marker imaged under a given set of conditions. Dark state transitions, fluorescence background, acquisition frame rate and illumination intensity all play a role in defining the spatial resolution for a given probe. Spectral resolution can be improved by incorporating a dispersive element in the detection path of a localization microscope, which can be useful for separation of multiple probes imaged simultaneously, and also for detection of changes in emission spectra of fluorophores resulting from changes in their (cellular) environment. Neural networks and new illumination geometries can improve the rate of identification of individual molecules, thus improving localization density and overall resolution. These methodological advances enable new biological applications, which in turn motivate new questions and technical innovations. In one such example, live- and fixed-cell imaging of the influenza viral protein hemagglutinin (HA), and host cell components, have revealed a relationship between HA, host cell actin, actin binding proteins, and the lipid phosphatidylinositol (4,5)bisphosphate (PIP2). Results will be discussed in the context of several existing models of plasma membrane organization.