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There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
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IBB Breakfast Club Seminar - Christine Payne, PhD - Assistant Professor, School of Chemistry and Biochemistry
Title: "Imaging Dynamic Events Inside Living Cells"
Abstract
Living cells carry out countless chemical reactions regulated by a variety of environmental parameters; concentration, diffusion, redox state, pH, and active transport. The goal of research in the Payne Lab is to understand the mechanism of intracellular reactions in relation to the cellular environment. Current research focuses on two aspects of cellular regulation; spatial localization of enzymes in vesicles and diffusion within the crowded environment of the cytosol. The highly heterogeneous environment of the cell requires a technique that can measure both the “where” and “when” of the event of interest. Video-rate fluorescence microscopy provides this information, but suffers from limitations associated with time-resolved imaging in the noisy environment of live cells. For this reason, we are simultaneously pursuing new approaches to the intracellular targeting of bright fluorophores and the development of new fluorescence microscopy systems for time-resolved cellular imaging. This seminar will focus on a specific example illustrating the role of spatially localized enzymes in the degradation of extracellular cargo. Using two-color single particle tracking, we have probed the intracellular degradation of low-density lipoprotein (LDL) in living cells. Individual LDL particles were labeled with multiple fluorophores resulting in a quenched fluorescent signal. Control experiments demonstrate that enzymatic degradation of the LDL particle results in an increase in fluorescence. Endocytic vesicles were fluorescently labeled with variants of GFP. We imaged the transient colocalization of LDL with early and late endosomes while simultaneously measuring the intensity of the LDL particle as an indicator of degradation. Using this imaging scheme to directly observe LDL degradation as a function of endosomal interactions, we show that degradation occurs in the late endosome and characterize the endosomal interactions necessary for degradation to occur. In the remaining time, I will discuss the fluorescence microscopy techniques being developed in the Payne Lab.
Continental breakfast will be provided.
