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Courtney "CJ" Johnson

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People / Courtney "CJ" JohnsonShroff Lab
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CV
Associate
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Current Research:

Phase-diversity-based Wavefront Sensing for Adaptive Optics in Fluorescence Microscopy
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As biologists probe more deeply into tissue, the information content of images degrades due to depth-dependent loss in signal and resolution. The ability to segment structures, count cells, and track motion eventually becomes impossible, preventing further interrogation of biology far from the coverslip.

This image degradation is rooted in distortion of the wavefront of light as it travels through the sample (optical aberrations). Adaptive Optics (AO) promises to reverse these aberrations to enable crisp, bright imaging of structures deep inside living tissues and organisms. However, this tool has not enjoyed broad adoption by the larger biological community because existing approaches to sense wavefront aberrations are slow, expensive, and difficult to use – even by expert microscopists.

Here at Janelia, I work in collaboration with theorists to develop a new computational approach to wavefront sensing that overcomes these barriers and ultimately enable widespread adoption of AO. 

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Biography

Courtney "CJ" Johnson received her Chemistry Ph.D. from Duke University in Durham, NC, where she learned how to build microscopes from an empty optical table to fully automated operation as a founding member of Kevin Welsher’s lab. During her time at Duke, she spearheaded the design of 3D-FASTR, a new method for 3D Point-Scan Microscopy, and led development of the 3D-TrIm single particle tracking microscope for visualizing high-speed virus-cell interactions in 3D. Before coming to Duke, CJ received her B.S. in Chemistry from Texas Woman’s University in Denton, TX.

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Education

Ph.D., Chemistry, Duke University
B.S., Chemistry, Texas Woman's University
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Featured Publications

3D-TrIm: High-Speed Single Particle Tracking
11/10/22 Capturing the start point of the virus–cell interaction with high-speed 3D single-virus tracking
The early stages of the virus–cell interaction have long evaded observation by existing microscopy methods due to the rapid diffusion of virions in the extracellular space and the large three-dimensional cellular structures involved. Here we present an active-feedback single-particle tracking method with simultaneous volumetric imaging of the live cell environment called 3D-TrIm to address this knowledge gap. 3D-TrIm captures the extracellular phase of the infectious cycle in what we believe is unprecedented detail.
3D-FASTR: High-Speed Point-Scan Volume Imaging
11/26/19 Continuous focal translation enhances rate of point-scan volumetric microscopy
Two-Photon Laser-Scanning Microscopy is a powerful tool for exploring biological structure and function due to its ability to optically section through a sample with a tight focus. While it is possible to obtain 3D image stacks by moving a stage, this per-frame imaging process is time consuming. Here, we present a method for an easy-to-implement and inexpensive modification of an existing two-photon microscope to rapidly image in 3D using an electrically tunable lens to create a tessellating scan pattern which repeats with the volume rate.