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www.sciencemag.org/content/344/6181/319/suppl/DC1
Supplementary Materials for
Distinct Profiles of Myelin Distribution Along Single Axons of
Pyramidal Neurons in the Neocortex
Giulio Srubek Tomassy, Daniel R. Berger, Hsu-Hsin Chen,
Narayanan Kasthuri, Kenneth J. Hayworth, Alessandro Vercelli, H.
Sebastian Seung, Jeff W. Lichtman, Paola Arlotta*
*Corresponding author. E-mail: [email protected]
Published 18 April 2014, Science 344, 319 (2014) DOI:
10.1126/science.1249766
This PDF file includes
Materials and Methods Supplementary Text Figs. S1 to S5 Tables
S1 and S2 References Movies S1 to S3
Other Supplementary Material for this manuscript includes the
following: (available at
www.sciencemag.org/content/344/6181/319/suppl/DC1)
Movies S1 to S3
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Materials and Methods:
Mice Wildtype C57Bl/6 mice were purchased from Charles River
Laboratories. Dab1-/- mice
were purchased from Jackson Laboratories. Emx1-Cre;RhoAfl/fl
mice were previously
described(22). All animal studies were approved by the Harvard
University Institutional
Animal Care and Use Committee (IACUC) and performed in
accordance with
institutional and federal guidelines.
Tissue Preparation and Electron Microscopy For the generation of
the adult mouse S1 dataset, brain samples were prepared as
described previously(26). Briefly, one adult mouse was perfused
with 2.5%
glutaraldehyde/2.0% paraformaldehyde in 0.1 M sodium cacodylate
buffer (pH 7.4).
Tissues were dissected, fixed for 2–4 hrs in the same fixative,
rinsed, and stored at 4°C in
0.1 M cacodylate buffer (pH 7.4). The samples were processed
according to the ROTO
protocol(26), dehydrated in graded ethanol solutions, and
embedded in epoxy resin
(Polybed, Polysciences, Warrington) following standard
procedures. The cerebral cortex
was cut and collected on kapton tape (glow discharged to prevent
wrinkling of sections)
with an ATUM (automatic tape-collecting ultra microtome) at 30
nm slice thickness(27,
28)(28). The tape containing all the sections was cut into
strips, mounted on 4 inch
silicon wafers (University Wafers, South Boston) and then carbon
coated (Denton 502B,
Moorestown) to provide grounding for the electron imaging. Every
eighth section was
imaged using a Zeiss Sigma scanning electron microscope at a
resolution of 30x30 nm
per pixel (carbon-coated, backscatter imaging(29)), yielding an
image stack with a voxel
size of 30x30x240 nm and a total imaged volume of ~ 1000x500x61
µm3.
Tracing and rendering
Cell bodies, axons and myelin sheaths were labeled manually
throughout the EM image
stacks, using a software tool (Volume Annotation and
Segmentation Tool, VAST). VAST
allows users to draw in colors over voxel data sets. All
tracings can be reproduced using
the TrakEM2 plug-in of the Fiji framework(10) . Resulting
labeled images and meta-data
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about the labels were exported and processed externally. For
rendering, 3D surface
meshes of labeled objects were generated from the exported data
using MATLAB scripts
developed in house (The MathWorks Inc.) and final 3D renderings
were generated using
3ds Max (Autodesk Inc.). To measure distances and lengths,
fiducials were painted at
points of interest in VAST, and MATLAB scripts generated in
house were used to
compute Euclidian distances between such fiducials. In the V1
data set the pia surface is
horizontal and therefore a single Y coordinate was used to
compute the distance of each
label from the pia. In the S1 data set the pia is oblique and
therefore three points on the
pial surface were used to approximate the position of the pia
and the Y coordinate of each
label was measured as the distance from that plane.
Immunohistochemistry, in situ hybridization and histology
Mouse brains for immunohistochemistry were processed as
previously described(30).
Primary antibodies and dilutions were as follows: rat anti-MBP,
1:100 (Millipore,
MAB386); mouse anti-MBP, 1:100 (Abcam, ab62631); rabbit
anti-CUX1, 1:100
(SantaCruz, M-222); rat anti-CTIP2, 1:1,000 (Abcam, ab18465);
goat anti-SOX10, 1:100
(Santacruz, N-20); mouse anti-APC, 1:500 (Millipore, Ab-7).
Appropriate secondary
antibodies were from the Molecular Probes Alexa series and the
Vectastain ACB system
(Vector Labs). Non-radioactive in situ hybridizations were
performed on 40!μm-thick
vibratome sections mounted on superfrost slides (Fisher) using
reported methods(31).
Riboprobe for Pdgfrα was a gift of W.D. Richardson (University
College, London);
riboprobe for Plp1 was a gift of J.D. Macklis, (Harvard
University). For Golgi-Cox
impregnation stainings, adult brains (3-4 months old) from
C57Bl/6 mice were processed
using the FD Rapid GolgiStain kit following manufacturer’s
instructions (FD
NeuroTechnologies). 200 μm-thick coronal sections were prepared
using a vibrating
microtome. Pyramidal neurons located in layer II/III and V-VI
were randomly selected
and ImageJ 64 software was utilized to measure their position
within the cortical wall
(distance between the pial surface and the center of the neuron
soma) and the length of
their PMAS. For Black gold II stainings, 40!μm-thick vibratome
sections were mounted
on superfrost slides (Fisher) and processed following
manufacturer’s protocols (Histo-
Chem Inc.). Briefly, after rehydration, slides were incubated in
0.2% Black gold II in
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0.9% saline for 12–15 min at 60°C. After washing in distilled
water, slides were fixed in
sodium thiosulfate solution for 3 min at 60°C and then rinsed in
distilled water,
dehydrated through graded alcohols (50%,70%,100%), cleared in
xylene and mounted in
DPX (Sigma). For Gallyas stainings, adult macaque and human
cortices were processed
as previously described(32). Briefly, 20 μm-thick cryostat
sections (human tissue) or
40!μm-thick vibratome sections (macaque tissue) were washed in
ddH20, passed through
a series of graded acetic acid steps, and then incubated in
silver iodide solution (1% silver
nitrate) for 45' at room temperature. All tissue sections were
imaged using a Nikon 90i
fluorescence microscope equipped with a Retiga Exi camera
(Q-IMAGING) and
analyzed with Volocity image analysis software v6.0.1
(Improvision).
Human and macaque cortical tissue Specimens of adult human
somatosensory cortex (medial postcentral gyrus) were
obtained from the collection of human brains of the Institute of
Forensic Medicine at the
University of Turin, Italy. Specimens were fixed in 4%
paraformaldehyde in phosphate
buffer (PB) 0.1 M, pH 7.4 for four hours at 4°C, and
cryoprotected overnight in a 30%
sucrose solution before freezing, as previously described(33).
20 μm-thick sections were
cut on a cryostat. Specimens of adult Rhesus Macaque (Macaca
mulatta) somatosensory
cerebral cortex (medial postcentral gyrus) were from brains
described before. Briefly,
animals were deeply anaesthetized with ketamine (5–10 mg/kg,
i.m.) and metomidine (30
μg/kg, i.m.) and perfused transcardially with isotonic saline
followed by 4%
paraformaldehyde in 0.1 M PBS. Animal surgery, preoperative, and
postoperative care
were performed according to Italian (DL.vo 116/92) and European
(Directive 86-609 EU)
guidelines for experimentation on primates.
Cell quantification
For quantification of OPCs and OLs, anatomically matched
sections within the
somatosensory cortex were processed to detect Pdgfrα and APC (n=
2 mice per marker;
4 sections, 6-8 hemispheres per brain). Boxes of 300 pixels in
width and spanning the
thickness of the cortex were superimposed at matched locations
on each section and
divided into ten equally-sized bins. Cells were manually counted
in each bin, and bin-
-
distribution was defined as the percentage of cells in each bin
relative to the total number
of cells.
Statistical analysis
All data are reported as the mean!±!s.e.m.. Normally distributed
data were analyzed using
a Student’s t-test. For data that were not normally distributed
a Mann–Whitney U-test
was used.
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Gallyas Nissl
Gallyas Nissl
Mac
aque Hu
man
II/III
IV
V
VI
I
MBPwild type ( 1.5 year )
A
B
giulio srubek tomassyFig. S1
giulio srubek tomassy
(A) Histological staining of myelin by Gallyas on coronal
sections of macaque and human sensory corticesshowing graded myelin
distribution. (B) Immunohistochemistry for MBP on a coronal section
of a 1.5 year old wild type mouse. Scale bars, 400 μm (A), 200 μm,
(B).
giulio srubek tomassyFig. S1. Reduced levels of myelin in the
upper layers are conserved in macaque and human neocortex and
maintained in aged mice.
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W= 500 m
D=60m
S1 Layer IV Layer VI
V1 Layer II/III
I
II/III
IV
V
VI
% m
yelin
cov
erag
e/to
tal a
xona
l len
gth
0
20
40
60
layer
VI
S1 lay
er IV
S1 lay
er II/I
II
V
1
***
***
A B
giulio srubek tomassyFig. S2
giulio srubek tomassyFig. S2. Different longitudinal coverage by
myelin along axons of upper and deep layer pyramidal neurons in the
adult mouse neocortex.
giulio srubek tomassy(A) Schematic of S1 dataset location in the
mouse brain and representative magnifications of layer VI and IV.
Also shown is a representativemagnification of layer II/III from
the V1 dataset. (B) Percentage coverage (mean±s.e.m.) by myelin of
axons in layers VI, IV (S1 dataset), and layerII/III (V1 dataset).
Scale bars, 20 μm.
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II/III
IV
I
giulio srubek tomassyFig. S3
giulio srubek tomassy Fig. S3. Relative distribution of
pyramidal neurons reconstructed in layer II/III of V1 dataset.
giulio srubek tomassyRendering of reconstructed neurons and
relative location on one representative image from the V1dataset.
Scale bar, 50 μm.
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Distance from pia ( m)1000800600400
*
***
giulio srubek tomassyFig. S4
giulio srubek tomassyFig. S4. Longitudinal profiles of
myelination on pyramidal neurons of the deep cortical layers.
giulio srubek tomassyHigh-resolution renderings of myelin
distribution along single axons of 12 layer V-VI pyramidal neurons
traced and reconstructed in the S1 dataset. Myelin is rendered in
white. Long unmyelinated tracts are indicated by asterisks. Scale
bar, 50 μm.
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1234 5
67
8
9
10
11
12
1 2
3 4
5 6
7 8
910
11 12
BA C
1
23
1
2
3
4
4
123
456
7
8
12
34
56
7
8
giulio srubek tomassyFig. S5
giulio srubek tomassyFig. S5. Distribution of synapses on
representative neurons in layer II/III of the V1 dataset axons.
giulio srubek tomassyHigh resolution renderings of (A) an
intermittent, (B) an unmyelinated and (C) a "long PMAS" neuron of
the V1 dataset. Insets show all traced synapses.Red and green dots
indicate the native position of each numbered synapse along the
axons. Red, afferent synapses, green, efferent synapses. Scale
bars, 50 μm (renderings), 0.5 μm (insets).
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Table S1. Spatial coordinates of axon hillocks of each neuron
reconstructed in layer
II/III of the V1 dataset. For best visualization of axons the
zoom level should be set at 1.
# neuron x y z Intermittent 54304 59560 134 Intermittent 62340
56800 152 Intermittent 52640 43844 712 Intermittent 86748 56916 536
Intermittent 84240 48096 560 Intermittent 98596 53488 530
Intermittent 55804 51224 206 Intermittent 91692 62112 576
Unmyelinated 65968 44788 180 Intermittent 117312 75372 878
Intermittent 89212 75376 864 Long PMAS 87944 64516 822
Unmyelinated 98340 51060 892 Long PMAS 116304 60704 838
Intermittent 70680 66920 306 Intermittent 58824 66696 362
Intermittent 61444 48764 202 Intermittent 56776 64808 610
Intermittent 80624 74056 942 Intermittent 43976
68784 714 Intermittent 97388 66480
960 Long PMAS 67112 43244 406
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Table S2. Quantification of all traceable synapses along each
axon labeled in the V1
dataset. For best visualization of synapses the zoom level
should be set at -1.
# neuron (myelination
profile)
# afferent synapses
# efferent synapses
Intermittent 3 0 Intermittent 6 0 Intermittent 6 0 Intermittent
2 0 Intermittent 5 2 Intermittent 1 2 Intermittent 4 0 Intermittent
2 0
Unmyelinated 3 0 Intermittent 3 0 Intermittent 1 0 Long PMAS 4
1
Unmyelinated 9 3 Long PMAS 3 1 Intermittent 6 0 Intermittent 3 1
Intermittent 7 1 Intermittent 5 0 Intermittent 1 0 Intermittent 2 0
Intermittent 8 1 Long PMAS 6 0
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Movie Captions
Movie S1. Movie through the XYZ-axes of the V1 dataset showing
reconstruction and
tracing of one intermittently myelinated neuron.
Movie S2. Movie of navigation along the Z-axis through 75 slices
in layer VI of the S1
dataset.
Movie S3. Movie of navigation along the Z-axis through 75 slices
in layer IV of the S1
dataset.
Additiional Data (separate files) Movies S1 to S3.
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