eBook: Advancing Neuroscience Research - 8

Another type of super resolution, stochastic optical
reconstruction microscopy (STORM), reconstructs a
super-resolution image from stochastic emissions
of individual fluorophores within a specimen. A
group led by Erin Schuman at the Max Planck Institute
for Brain Research recently used Nikon's
N-STORM system to study protein synthesis within
dendrites during synaptic plasticity.7
" Local synthesis
is required for synaptic plasticity, but little is
known about the level and specific location of the
necessary molecular tools, " says White. " This proves
to be a perfect application for N-STORM. " Using
metabolic labeling and DNA-PAINT (DNA point
accumulation in nanoscale topology, a super-resolution
imaging method using short DNA oligonucleotides
labeled with fluorophores), Schuman's
group detected dendritic ribosomes and nascent
proteins at single-molecule resolution, and found
that local protein synthesis was correlated with the
level of synaptic activity.
Single-molecule imaging within
the brain
The brain's unique spatial organization makes it a
prime target for investigation by microscopy-especially
as techniques mature in both resolution
and molecular capabilities. Vizgen's MERSCOPE
platform uses MERFISH (multiplexed error-robust
fluorescence in situ hybridization), a single-molecule
imaging technology that can measure the
copy number of up to 100s of 1000s of RNA molecules
simultaneously, with subcellular resolution.
" The MERSCOPE platform enables spatially profiling
the expression of hundreds of genes across full
tissue slices, revealing the exact three-dimensional
coordinates of nearly all copies of the targeted
transcript with better than 100 nm accuracy, " says
George Emanuel, Scientific Cofounder, Director of
Technology and Partnerships at Vizgen.
High-resolution spatial profiling of gene expression
is a powerful mapping tool for any type of
tissue. In the brain, researchers are dissecting complex
interactions, such as the migration of microglial
cells down blood vessels during development.
" Only high-resolution transcriptome profiling is
able to distinguish the microglia transcription from
the transcription in the blood vessels, " says Emanuel.
" This unveils a window into the composition of
the brain that was not feasible with previous commercially
available technologies and is particularly
relevant in neuroscience research. "
Spatial profiling is turbo-charging cell atlas efforts
in the brain by delivering positional information of
individual cells within tissues (previous methods
typically involved tissue dissociation followed by
single-cell sequencing). Using MERFISH and a retrograde
tracer to map neuronal connections from
terminus to source, researchers can identify the
subtypes of neurons involved. A group led by Xiaowei
Zhuang at Harvard University recently used
this method to generate a cell atlas of the mouse
primary motor cortex, and investigated the projection
patterns of intratelencephalic neurons.8
They
also found that neurons from the primary motor
cortex send and receive information to other areas
in neuronal clusters.
Microscopy is advancing neuroscience still further
to provide high-resolution images of live neurons
and glial cells. A new study led by Robert Prevedel
at the European Molecular Biology Laboratory uses
several methods including adaptive optics 3-photon
microscopy to obtain high-resolution images
deep within live brain tissue.9
All of these results inspire
future avenues of inquiry for neuroscientists
armed with the latest microscopy techniques.
8
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