38
Figure 3: Resolution of proximal cortical microtubules labeled with GFP-MBD microtubule
954
marker, comparing SIM, WF and CLSM. (A to C) The same cortical area of a hypocotyl
955
epidermal cell expressing GFP-MBD fusion protein showing two adjacent microtubules by SIM
956
(A; full view in Fig. S5A), WF (B; full view in Fig. S5B) and CLSM (C; full view in Fig. S5C).
957
(D to F) Normalized fluorescence intensity profiles corresponding to white lines in (A to C),
958
showing clear discrimination of the two adjacent microtubules as two peaks in SIM (D) in
959
contrast to the fluorescence intensity profiles obtained from the respective WF (E) and CLSM
960
(F) acquisitions showing only one peak. (G to I) Different areas from the same cell visualized
961
with SIM (G; full view in Fig. S5D), WF (H; full view in Fig. S5E) and CLSM (I; full view in
962
Fig. S5F). White lines across adjacent microtubules represent the position from which
963
fluorescence intensity profiles were acquired and correspond to the Rayleigh resolution limit
964
(i.e., peak-to-peak discrimination at ca. 25% depression of maximum fluorescence intensity). (J
965
to L) Quantitation of the corresponding intensity profiles shown in (G to I). Brackets denote the
966
peak-to-peak separation at the Rayleigh limit. (M) Graph depiction of the averaged Rayleigh
967
limits measured for SIM, WF and CLSM (mean
±SD, n=32 measurements in all cases; *,
968
p<0.001 comparing Rayleigh limits from SIM with WF and CLSM). Scale bars for all Figures: 5
969
μm.
970
Figure 4: Resolution of individual cortical microtubules of Arabidopsis thaliana hypocotyl
971
epidermal cells, labeled with GFP-MBD (A, C, E, G, I) or GFP-TUA6 (B, D, F, H, J) during
972
time-lapsed imaging with SIM (A, B), WF (C, D), CLSM (E, F), TIRF (G, H) and SD (I, J)
973
microscopies. Scatter plots represent averaged weighted profiles of many individual
974
microtubules. (A, B) Resolution of individual cortical microtubules labeled with GFP-MBD (A;
975
n=40) and GFP-TUA6 (B; n=71) after SIM imaging. (C, D) Resolution of individual cortical
976
microtubules labeled with GFP-MBD (C; n=40) and GFP-TUA6 (D; n=71) after WF imaging.
977
(E, F) Resolution of individual cortical microtubules labeled with GFP-MBD (E; n=41) and
978
GFP-TUA6 (F; n=43) after CLSM imaging. (G, H) Resolution of individual cortical
979
microtubules labeled with GFP-MBD (G; n=41) and GFP-TUA6 (H; n=47) after TIRF imaging.
980
(I, J) Resolution of individual cortical microtubules labeled with GFP-MBD (I; n=54) and GFP-
981
TUA6 (J; n=83) after SD imaging. Black lines are positioned to a normalized fluorescence
982
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39
intensity (0.5) corresponding to the FWHM of each respective curve. Scale bars for all Figures: 5
983
μm.
984
Figure 5: Independent and intrabundle dynamics of GFP-MBD and GFP-TUA6-labeled cortical
985
microtubules visualized by SIM. (A to C) Overview (A) of a hypocotyl epidermal cell
986
expressing GFP-MBD microtubule marker during time-lapsed imaging with SIM, selected stills
987
of a free microtubule visible at both ends (right boxed area in A; B) and respective kymograph of
988
the same microtubule exhibiting short length transitions of growth and shrinkage (full
989
arrowheads; C). (D) Kymograph representing dynamics of free cortical microtubule (corresponds
990
to Figs. S6A, B; Video S1) visible at one end showing smooth, uninterrupted growth (solid lines)
991
and shrinkage (catastrophe; dotted line). (E to G) Overview (E) of a hypocotyl epidermal cell
992
expressing GFP-TUA6 microtubule marker, selected stills of a fully visible independent
993
microtubule (boxed area in E; F; arrowheads point to plus end; Video S2) and respective
994
kymograph showing dark and bright striations owing to the inhomogeneous incorporation of
995
GFP-TUA6 in the microtubule lattice (G). (H) Another kymograph of a GFP-TUA6-labeled
996
microtubule where minus end behavior can be followed (corresponds to Figs. S6C, S6D). (I)
997
Selected stills of a microtubule growing within a bundle from the top right boxed area in (A). (J)
998
The respective kymograph showing vigorous plus end dynamics and short length excursions in
999
the plus end (arrowheads) and minimal dynamics at the minus end. (K) Longitudinal
1000
fluorescence intensity profile along the bundle encompassing the microtubule tracked in (I). (L)
1001
selected stills of a short intrabundle microtubule (arrowheads) selected from the left boxed area
1002
of (A). (M) The corresponding kymograph of the microtubule in (L) showing frequent and short
1003
length transitions in the plus end (full arrowheads) and dynamic instability at the minus end
1004
(open arrowheads). (N) The longitudinal fluorescence intensity profile harboring the short
1005
intrabundle microtubule depicted in (L). (O, P) Graphs depicting average plus and minus end
1006
growth and shrinkage rates reported for GFP-MBD and GFP-TUA6 labeled extrabundle (O) and
1007
intrabundle (P) microtubules from values summarized in Tables S1 and S3 for free and
1008
intrabundle microtubules respectively. All full arrowheads point to plus ends and all open
1009
arrowheads point to minus ends. Scale bars: 5
μm (A, E), 2 μm (B, F, G, L), 1 μm (C, D, I, J, M)
1010
and 0.5
μm (H). Time bars in kymographs: 127.85s (C), 80s (M), 60s (J) 34.5s (D), 30s (G) and
1011
10s (H). (+) indicate microtubule plus ends and (-) indicate microtubule minus ends. Numbers in
1012
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40
(B, F, I, L) are in min:sec.msec. In all kymographs (C, D, G, H, J, M) time evolution is from top
1013
to bottom.
1014
Figure 6: Overview of independent cortical microtubule dynamics of hypocotyl epidermal cells
1015
of the mpk4 mutant expressing GFP-MBD fusion protein, as visualized by SIM and quantified
1016
accordingly. (A to C) Widefield SIM view (A), selected stills (B) from the boxed area in (A) and
1017
respective kymograph showing a shrinkage (C, dotted line) and a successive growth event (C,
1018
full line). (D) Another kymograph of a free growing microtubule showing two growth phases
1019
with different rate (full lines) interrupted by one catastrophe (dotted line). Arrowheads denote
1020
minor such transitions. (E) Graphic illustration of plus and minus end dynamics of free
1021
microtubules observed by SIM in hypocotyl epidermal cells of GFP-MBD-transformed mpk4
1022
mutants as summarized in Table S1. Scale bars: 5
μm (A), 2 μm (B), and 1 μm (C, D). Time bars
1023
in (C, D) 60 s. (+) indicate microtubule plus ends. Numbers in (B) are in min:sec.msec. In all
1024
kymographs (C, D) time evolution is from top to bottom.
1025
Figure 7: Intrabundle microtubule dynamics of the GFP-MBD expressing mpk4 mutant as
1026
acquired with SIM. (A) Overview (A; see also Video S3) of an mpk4 hypocotyl epidermal cell
1027
with GFP-MBD-labeled microtubules, exhibiting extensive cortical microtubule bundling (boxed
1028
areas). (B) Selected stills of a short microtubule (from left bottom boxed area in A; open
1029
arrowheads) growing on the tip of a cortical microtubule bundle. From the same bundle a free
1030
microtubule extends away by its plus end (red arrowhead). Temporal changes of the longitudinal
1031
profile illustrated in H, can be seen in Fig. S (C) Selected stills from the right boxed area in (A)
1032
of a microtubule bundle showing two discrete short microtubules (denoted by orange and white
1033
full arrowheads respectively). Red full arrowhead shows depolymerizing microtubule in the
1034
same bundle and full and open blue arrowheads show a short gap visible as a steep fluorescence
1035
intensity depression in (I). (D) Selected stills of a short microtubule growing (full arrowheads)
1036
upon a bundle from the top left boxed area in (A). (E to G) Kymographs corresponding to B (E),
1037
C (F) and D (G) respectively. Arrowheads in (E to G) are tracking the respective positions shown
1038
in (B to D). (H to J) Longitudinal fluorescence intensity profiles drawn along the microtubule
1039
bundles depicted in the last frames of B (H), C (I) and D (J). (K) Vertical fluorescence intensity
1040
profiles corresponding to the colored lines in the last frame of (B; blue line, 1 microtubule; green
1041
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41
line, 2 microtubules; red line, three microtubules) demonstrating the complexity of the respective
1042
bundle. (L) Graph depiction of plus and minus end intrabundle microtubule dynamics in the
1043
mpk4 mutant as summarized in Tables S3 and S4. Scale bars: 5
μm (A), 2 μm (B to D), 1 μm (F)
1044
and 0.5
μm (E, G). Time bars in kymographs: 35 s (E to G). Numbers in B to D min:sec.msec. In
1045
all kymographs (E to G) time evolution is from top to bottom.
1046
Figure 8: Lateral-tip interaction between aberrant, short and rigid microtubule bundles with the
1047
walls of individual microtubules labeled with GFP-MBD marker in mpk4 mutant as visualized
1048
by SIM. (A to D) Overview of hypocotyl epidermal cell of mpk4 mutant expressing GFP-MBD
1049
fusion protein as in Fig. 7A (A; see also Video S3), and time series of two short and rigid
1050
microtubule bundles (from boxed area in A; (B) First bundle (full arrowhead) shows short range
1051
rapid gliding along the mother microtubule. Second bundle (open arrowhead) swings freely and
1052
randomly around its stable anchorage on the site of the mother microtubule. (C, D) Respective
1053
kymographs of the short, rigid bundles shown with full and open arrowheads in (B) to
1054
demonstrate their rapid, random motility while maintaining stable attachments (C, arrowhead
1055
shows the tip of the rigid bundle pointed by open arrowhead in B as it approaches an opposing
1056
microtubule (arrow in B, asterisk in C); arrowhead shows to back and forward gliding
1057
transitions). (E, F) Absolute fluorescence intensity profiling (dark grey in E and F) of the
1058
microtubule bundle (open arrowhead in B) referenced against single microtubule (light grey in E
1059
and F). Fluorescence intensity of bundle is about 3-fold increased compared to that of the
1060
individual microtubule suggesting it comprises of three microtubules. Scale bars: 5
μm (A), 1 μm
1061
(B, E), 0.5
μm (C, D). Numbers on time frames time in min:sec.msec. Time bars in kymographs
1062
(35.16s). In all kymographs (C, D) time evolution is from top to bottom.
1063
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0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
0
2000 4000 6000 8000 10000 12000 14000
2:41.608
2:09.290
1:36.968
1:04.647
32.325
Figure 7: Intrabundle microtubule dynamics of the GFP-MBD expressing mpk4 mutant as acquired with SIM. (A) Overview (A; see also Video S3) of an mpk4
hypocotyl epidermal cell with GFP-MBD-labeled microtubules, exhibiting extensive cortical microtubule bundling (boxed areas). (B) Selected stills of a short
microtubule (from left bottom boxed area in A; open arrowheads) growing on the tip of a cortical microtubule bundle. From the same bundle a free microtubule
extends away by its plus end (red arrowhead). Temporal changes of the longitudinal profile illustrated in H, can be seen in Fig. S (C) Selected stills from the
right boxed area in (A) of a microtubule bundle showing two discrete short microtubules (denoted by orange and white full arrowheads respectively). Red full
arrowhead shows depolymerizing microtubule in the same bundle and full and open blue arrowheads show a short gap visible as a steep fluorescence intensity
depression in (I). (D) Selected stills of a short microtubule growing (full arrowheads) upon a bundle from the top left boxed area in (A). (E to G) Kymographs
corresponding to B (E), C (F) and D (G) respectively. Arrowheads in (E to G) are tracking the respective positions shown in (B to D). (H to J) Longitudinal
fluorescence intensity profiles drawn along the microtubule bundles depicted in the last frames of B (H), C (I) and D (J). (K) Vertical fluorescence intensity
profiles corresponding to the colored lines in the last frame of (B; blue line, 1 microtubule; green line, 2 microtubules; red line, three microtubules)
demonstrating the complexity of the respective bundle. (L) Graph depiction of plus and minus end intrabundle microtubule dynamics in the mpk4 mutant as
summarized in Tables S3 and S4. Scale bars: 5
μm (A), 2 μm (B to D), 1 μm (F) and 0.5 μm (E, G). Time bars in kymographs: 35 s (E,F,G). Numbers in B to D
min:sec.msec. In all kymographs (E to G) time evolution is from top to bottom.
A
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2 MTs
3 MT
SIM
1:04.647
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0
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35000
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2000
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5000
6000
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-2
0
2
4
6
+ end
- end
shrinkage
growth
mpk4
μ
m/
mi
n
a
A
G
E
F
B
0.000
32.325
1:36.968
2:09.290
2:41.608
D
3:13.939
1:04.647
B
H
K
I
J
L
C
0.000
32.325
1:04.647
1:36.968
2:09.290
2:41.608
0.000
Profile length [nm]
Profile length [nm]
Profile length [nm]
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