Traditionally, light microscopes produce two-dimensional images of cells mounted on thin glass slides. Seeing inside cells to discern their components has been limited in resolution by the wavelength of light.
Now a researcher at the University of Texas Southwestern Medical Center is pushing the boundaries of light microscopy to include movies and three-dimensional images from inside living animals, as well as fine details of cells.
Reto Fiolka was recruited to join the faculty in the department of cell biology at UT Southwestern where he was already an instructor. Fiolka was being recruited to other universities around the world, and a CPRIT First-Time Tenure-Track Award was used to retain this talented microscopist in Texas.
Off-the-shelf, commercially available microscopes, Fiolka says, are often 10 years behind where cutting-edge development is happening. His goal is to not only expand the technological capabilities of light microscopes but also build them in such a way that they can be used in other laboratories on campus.
First, he is advancing the microscopes’ ability to capture images in 3D and in real time. He wants to record the dynamics of cells over time, and do it in such a way that the cells are not behaving differently either because of the environment they are in or the amount of light they are exposed to. Doing this requires the rapid acquisition of thousands of images that form the basis for a three-dimensional time series. For analyzing the large volume of data, Fiolka collaborates with UT Southwestern CPRIT Scholar Gaudenz Danuser, an expert in image analysis and computational biology.
Second, Fiolka is using adaptive optics to delve deeper into living tissues and organisms. Light microscopy is typically limited to very simple layers of tissues or samples because light can’t travel very deep. But to see deeper inside mixtures of cells or even animals, like the zebrafish or mouse, Fiolka is taking advantage of technology developed to allow telescopes to see deep into space without blurring from atmospheric distortions.
Imagine a car windshield splattered with raindrops, and the distorted image it creates for a driver. The idea of adaptive optics is measuring these distortions and then correcting for them, so that a clear image emerges.
Last, Fiolka is pushing the spatial resolution of light microscopes. Traditionally, light microscopes can’t resolve structures smaller than half the wave length of light, about 200 nanometers. This is enough to see the components of a cell, like the nucleus, or organelles like mitochondria, but cannot resolve finer structures inside organelles or individual filaments of the cytoskeleton. Electron microscopes allow scientists to study these elements in much finer detail, but can’t b e used on living cells.
Fiolka is trying to bridge the “resolution gap” between light and electron microscopes and allow living tissues to be imaged in much finer detail than has been possible till now, using what’s called “super resolution.”
Fiolka is excited to not only build cutting-edge microscopes but also to be able to use them for practical applications throughout the life sciences at UT Southwestern. “I have been in places where we could really build top instruments, but what was lacking were the applications,” he says. “There is a commitment at UT Southwestern to put us on the map as having both advanced imaging technologies and collaborative research.”
Fiolka received his master’s degree in mechanical engineering and Ph.D. in advanced light microscopy from ETH Zurich in Switzerland, and then trained with pioneers in the development of super-resolution light microscopy and adaptive optics at HHMI’s Janelia Farm Laboratory in Ashburn, VA. He first joined UT Southwestern in 2013 as an instructor in Danuser’s laboratory.
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