Carmichael’s Concise Review Coming Events
2019 PITTCON Conference & Expo 2019 March 17–21, 2019
Philadelphia, PA
https://pittcon.org
ACS Spring Meeting: Chemistry for New
Frontiers March 31–April 4, 2019
Orlando, FL
www.acs.org/content/acs/en/meetings/ national-meeting/abstract-submission. html?sc=meetings_1800815_mtg_%20OR19_od
FOM2019: Focus on Microscopy 2019 April 14–17, 2019
London, UK
www.microbeamanalysis.eu/events/ event/57-fom2019-focus-on-microscopy-2019
MRS Spring Meeting & Exhibit April 22–26, 2019
Phoenix, AZ
www.mrs.org/spring2019
PICO 2019 – Frontiers of Aberration Corrected Electron Microscopy May 5–9, 2019
Kasteel Vaalsbroek, Netherlands
www.er-c.org/pico2019/about.htm
EMAS 2019 – Modern Developments and Applications in Microbeam
Analysis May 19–23, 2019
Trondheim, Norway
https://www.microbeamanalysis.eu
Microscopy & Microanalysis 2019 August 4–8, 2019
Portland, OR
www.microscopy.org
2020 Microscopy & Microanalysis 2020 August 2–6, 2020
Milwaukee, WI
www.microscopy.org
2021
Microscopy & Microanalysis 2021 August 1–5, 2021
Pittsburgh, PA
www.microscopy.org
2022 Microscopy & Microanalysis 2022 July 31–August 4, 2022
Portland, OR
www.microscopy.org
2023
Microscopy & Microanalysis 2023 July 24–28, 2023
Minneapolis, MN
www.microscopy.org
2024 Microscopy & Microanalysis 2024 July 28–August 1, 2024
Cleveland, OH
www.microscopy.org
More Meetings and Courses Check the complete calendar near the back of this magazine.
8
Combining Microscopies Allows Molecular Contrast at Nanoscale Resolution
Stephen W. Carmichael Mayo Clinic, Rochester, MN 55905
carmichael.stephen@
mayo.edu
Neural circuits across the brain are composed of structures that vary in size
about ten million-fold. No one imaging modality can examine all the significant structures across that span. Electron microscopy (EM) excels at looking at the smallest structures, but confocal fluorescence microscopy can image the larger structures with labels to yield information about the molecular composition of the structures. Authors Ruixuan Gao, Shoh Asano, and Srigokul Upadhyayula, led by Nobel Laureate Eric Betzig and neuroscientist Edward Boyden, combined two imaging modalities that not only covered this huge range of size differences, but also identified the molecular constituents of the specimen, such as the proteins, across the range [1]. One of the modalities they used was expansion microscopy (ExM), which was
reviewed in this column in 2015 (Microscopy Today, 23(3) (2015) 8–10). Basically this technique involves adding a water-absorbent polymer gel to preserved tissue. When transferred from a saline solution to pure water, the polymer swells, stretching the tis- sue approximately four-fold. Te imaging relies on fluorescent tags that attach specifi- cally to proteins in cells and tissues and also to the surrounding gel. Te proteins are digested to leave the fluorescent molecules exactly in place, and the relative positions between these molecules are maintained aſter the swelling. Te expanded specimen was imaged by Gao et al. using lattice light-sheet
microscopy (LLSM), which was also reviewed in this column (Microscopy Today, 23(1) (2015) 8–10). Briefly, this technique sweeps an ultrathin layer of light through the tissue. By using a less intense light than is required for other methods, the beam can linger on the sample while not bleaching the fluorescence or obscuring part of the image. Since it is relatively fast, LLSM illuminates a whole plane at one time rather than a single spot. It could gather enough information to image the entire
Figure 1: Dopaminergic neurons and the associated presynaptic sites across an adult fruit fly brain, color-coded by brain regions. Image width = 660 µm.
doi:10.1017/S1551929519000245 2019 March
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