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Joint Seminar:  Departments of Biophysics and  Bioinformatics 

 

Peter Dahlberg, Ph.D. Panofsky Research Fellow, SLAC National Accelerator Laboratory

Title:Combining cryogenic fluorescence and electron microscopy: New methods with applications from biology to physical chemistry 

Abstract: Both fluorescence and cryogenic electron microscopy have undergone major advances in the past decade. These advances have enabled a deeper understanding of a broad range of biological and synthetic systems. Despite the strength of both of these imaging modalities, each suffers from unique limitations. Fortunately, many of these limitations can be circumvented when complementary information from each of the two methods is integrated into a single approach known as cryogenic correlative light and electron microscopy (CryoCLEM). Traditionally, CryoCLEM has focused on combining diffraction-limited fluorescence information with cryogenic electron tomography (CryoET) of cellular samples. In these experiments, the low-resolution fluorescence image has primarily been used to guide the CryoET acquisition to cellular regions of interest. Here I will discuss two new and powerful ways that fluorescence and CryoET can be combined to provide a more biologically informative picture. The first approach involves the development of single-molecule-based cryogenic super-resolution fluorescence microscopy, which enables the precise locations of proteins of interest to be determined within the cellular context provided by CryoET. The second approach uses ratiometric fluorescent biosensors to correlate aspects of the local environment (such as pH, ion concentrations, redox, etc.) with ultrastructural observations from CryoET, providing critical chemical information for the interpretation of the observed physical structures. I will conclude with a brief perspective on the future of correlative methods and anticipated developments which will have the most profound impact on diverse fields of study.

Speaker Bio: Peter Dahlberg was named in 2021 Panofsky Fellow in the Department of Energy’s SLAC National Accelerator Laboratory.  He completed his postdoc training with W. E. Moerner at Stanford, and continues to work closely with him and  Stanford professor Wah Chiu. His research focus is on developing new methods and technology to study the function and behavior of proteins inside the cell by combining fluorescence methods with CryoEM.

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