EPFL biophysicists have developed a high-throughput super-resolution microscope to probe nanoscale structures and dynamics of mammalian cells, showing in unprecedented detail the twists and turns of an organelle important for cell division

Date:
June 22, 2020
Source:
Ecole Polytechnique Fe'de'rale de Lausanne
Summary:
Biophysicists have developed a high-throughput super-resolution
microscope to probe nanoscale structures and dynamics of mammalian
cells, showing in unprecedented detail the twists and turns of an
organelle important for cell division.



FULL STORY ==========================================================================
If you want to understand the underlying mechanisms of cellular motility
and division, then the centriole is the organelle of interest. Each cell
has a pair of centrioles which help to segregate chromosomes during cell division. These special organelles are multi-molecular machines composed
of hundreds of proteins and have a hidden code of post-translational modifications (PTMs), that contribute to their rigidity or flexibility,
which in turn may help explain how centrioles function.


========================================================================== Based on previous studies mostly using electron microscopy, the
basic structure of centrioles is known. But PTMs are invisible to the
electron microscope, so what do they look like? Thanks to improved
super resolution fluorescence microscope technology developed by EPFL biophysicists, we now have a detailed picture of these nanoscale
structures, both isolated and in situ. As expected, the centrioles
are shaped like ridged bullets, i.e. they are cylindrical with nine
lengthwise ridges and their diameter tapers off at one end. Given this
high degree of organization, the scientists were surprised to find that
one PTM actually twists around these ridges. The results are published
today in Nature Methods.

"The symmetries of multi-molecular machines often explain how they
can perform diverse functions. PTMs can form a special code that tells
proteins where to dock, but can also stabilize the centriole while forces
are pulling during division. We still don't know why the twist is there,
but it offers a clue to how centrioles work. Our study underlines that super-resolution microscopy is an important partner to electron microscopy
for structural biology," says biophysicist Suliana Manley who leads the Laboratory of Experimental Biophysics (LEB).

Improved super resolution imaging techniques Centrioles are about 100
times smaller than a mammalian cell, and a thousand times smaller than a
human hair. So observing them inside of living cells required improving super-resolution microscope technology that uses light to probe specimens, since the methods tend to be too slow for structural studies.

Dora Mahecic, a PhD student in the LEB, improved the illumination
design to increase the size of images their microscope could capture by delivering light more uniformly across the field of view.

The microscope, a super-resolution fluorescence microscope, is not at
all the typical optical microscope that one would see in an introductory biology class.

It is actually a complex setup of carefully aligned mirrors and lenses
that shape and deliver laser light into the specimen. The biophysicists combined this setup with advanced sample preparation that uses physical magnification of the sample and fluorophores to make proteins, the
building blocks of life, re- emit light.

This new super resolution technology could be used to study numerous other structures within the cell, like mitochondria, or to look at other multi- molecular machines such as viruses.


========================================================================== Story Source: Materials provided by
Ecole_Polytechnique_Fe'de'rale_de_Lausanne. Original written by Hillary Sanctuary. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Dora Mahecic, Davide Gambarotto, Kyle M. Douglass, Denis Fortun,
Niccolo'
Banterle, Khalid A. Ibrahim, Maeva Le Guennec, Pierre Go"nczy,
Virginie Hamel, Paul Guichard, Suliana Manley. Homogeneous
multifocal excitation for high-throughput super-resolution
imaging. Nature Methods, 2020; DOI: 10.1038/s41592-020-0859-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200622133045.htm

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