Knutson - 2019

Laboratory of Advanced Microscopy and Biophotonics
Lab Chief
Rozhin Penjweini, Ph.D
NHLBI
Mentor Name
Jay R. Knutson, Ph.D.
Mentor Email
Mentor Telephone
(301) 496-2557
Laboratory And Project Description

We develop and exploit the techniques of ultrafast laser microscopy. We develop state-of-the-art instruments that help us determine the local flexibility, size, and structure of protein or DNA complexes both in solution and inside living cells. For years, we have been developing 2-photon, lifetime and FCS microscopy methods to extend a detailed spectroscopic approach to the cellular level. We have, for example, recently developed an intracellular sensor for [O2] based on Myoglobin-mCherry chimeras, and we are using that construct with FLIM to map oxygen levels in various organelles, cells and tissues (and also oxygen gradient chambers for tumor simulation).  We couple that metabolic sensor with our prior work mapping the free/bound ratio of NADH in cells including cardiac mitochondria (2p lifetime).  Using other microscopes sensitive to protein mobility, we have  e.g. quantified the binding of HIV nef to receptor CD4 by monitoring cross-correlation in translation (FCS), and also mobility of oncogene TFs in nuclei. We have collaborated with NHLBI/LCE in the creation of new fs CARS microscopes to study water permeation across vessel walls, and we continuously develop global analysis tools for imaging. We have recently developed new 'superresolution' methods to calibrate and observe <100nm resolution images in fluorescence microscopy - using both STED and our own novel "STAQ" dyes (requiring much less STED power). We also collaborate on lifetime studies in cuvettes or the microscope to help characterize novel bright fluorescent aptamers.

Depending on their interests, summer interns will all be introduced to fluorescence instruments and image/data acquisition-- plus:

  • Help exploit superresolved acquisition of cell images in novel microscopes, using transfected versions of the STAQ architecture.
  • Help test and exploit our novel fluorescence chimera that senses intracellular [O2] levels.
  • Help develop computer software to "globally" analyze either features and flexibility of proteins and DNA, FRET of aptamers, or micro/nanoscopic image sets in cells.
  • Exploit FLIM (Fluorescence Lifetime Microscopy) features to push STED/STAQ resolution below 500A.

Feel free to call for more information.