Subgroup: Membrane Structure & Assembly

[2] A. Zu¨rner et al., Nature 450, (2007), 705; J. Kirstein et al.; Nature Mat.6, (2007), 303; C. Jung et al., Nature Nanotechnology 6 (2011), 87.[3] T. Lebold et al., NanoLetters 9 (2009) 2877; V. Cauda et al., NanoLetters,10 (2010), 2484; A. Sauer, NanoLetters, 10 (2010), 3684; T. Lebold et al.,Advanced Functional Materials, (2011) accepted.30-SubgAdvances in Image Correlation Spectroscopy for Measurements inHeterogeneous Cell EnvironmentsPaul W. Wiseman, Ph.D.Physics, McGill University, Montreal, QC, Canada.Image correlation spectroscopy (ICS) methods provide a spatial regime basedapproach for measurements of membrane associated protein-protein interac-tions and macromolecular transport properties using fluorescence microscopyimages of living cells as input. These approaches are based on space andtimecorrelation analysisoffluctuationsinfluorescenceintensitywithinimagesrecorded as a time series on a laser scanning or TIRF microscope. We recentlyintroduced spatio-temporal image correlation spectroscopy (STICS) whichmeasures vectors of protein flux in cells based on the calculation of a spatialcorrelation function as a function of time from an image time series. Herewe will describe extensions of (ICS) that are suited for measurements in theheterogeneous cell environment. We will introduce a two color extension,spatio-temporal image cross-correlation spectroscopy (STICCS) with a bivari-ate fitting method that accounts for directional confinement in the cell. We willillustrate the method with transport maps of the adhesion related macromole-cules alpha5, alpha6 and alphaL integrins with paxillin, and actin within, or as-sociated with the basal membrane in adherent cells plated on extracellularmatrix components laminin, collagen or fibronectin. Using the method we de-tect transient flow patterns as well as anisotropic diffusion that are correlatedwith adhesion fluxing activity in specific regions of the cell. Finally we willalso highlight recent advances we have made with an extension of reciprocal(k-) space ICS (kICS) that can be used to measure molecular confinement inmembrane domains from analysis of the correlation functions in both k-spaceand time.31-SubgInvitedSaturday SubgroupSpeakerFluorescentProteins:TheShowMustGo On!Gregor Jung.Biophysical Chemistry, Saarland University, Saarbruecken, Germany.A half century ago, Green Fluorescent Protein (GFP) from a pacific jellyfishwas isolated as byproduct in the purification of the chemiluminescent proteinAeqourin. While the latter was later turned into a calcium-sensitive probe,GFP was treated like a fluorescent curiosity in biophysical research for almostthree decades. Once it was recognized that fluorescence appears without theneed of cofactors, the transfection into other organisms proved the autocatalyt-ical character of chromophore formation and boosted the research in life sci-ences. The discovery of the GFP, its first, seminal application and theingenious development of a broad palette of fluorescence proteins, was conse-quently awarded with the Nobel Prize for Chemistry in 2008.In my presentation, I will review the highlights in the history of GFP and otherfluorescent proteins from a spectroscopist’s point of view. Furthermore, openquestions and new ideas how fluorescentproteins can be turned into biosensorswill be discussed.32-SubgColor Coded Optical Nano-Sectioning (COCOS) Reveals Focal AdhesionDynamicsKareem Elsayad