Title:  Advances in Localization Microscopy

Speaker:  Sam Hess, The University of Maine

When:  Monday, June 6, 2011   9:00 am

Where:  UMaine, Fogler Library Media Services (Video Conference room at the back of Fogler library (1st floor); Jackson Lab IMB conference room, and KIP University of Heidelberg.  Also select video locations at University of Virginia, MIHGH, MDIBL, .  


  Diffraction limits resolution in visible light microscopy to ~200-250 nanometers. However, many biological functions are regulated at the molecular level. FPALM (fluorescence photoactivation localization microscopy), can break the diffraction limit and can achieve effective lateral resolution in the tens of nanometers. FPALM performs successive rounds of photoactivation, imaging, localization, and photobleaching, to obtain the coordinates of large numbers of probe molecules. The image is then generated by plotting the measured positions of all successfully localized molecules. Biological applications of FPALM to intracellular membrane, cytosolic, nuclear, and cytoskeletal proteins have been demonstrated, including results from live cells, fixed cells, and fixed tissue. Dynamics of individual molecules, including trajectories, can be recorded and quantified do determine molecular diffusion properties or velocities. Three-dimensional imaging using Bi-plane FPALM has recently been demonstrated to yield 30 nm x 30 nm x 70 nm resolution. Polarization FPALM can measure both the positions and orientations of localized probe molecules in biological samples, and has been used to image cytoskeletal and membrane proteins in cells. Multicolor FPALM allows detection of three or more fluorescent species in living or fixed specimens. These powerful capabilities offer great potential for biological applications.