First published online October 19, 2007
Journal of Experimental Biology 210, 3805-3820 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.005439
Assessment of sperm chemokinesis with exposure to jelly coats of sea urchin eggs and resact: a microfluidic experiment and numerical study
Munish V. Inamdar1,
Taeyong Kim1,
Yao-Kuang Chung2,
Alex M. Was1,
Xinran Xiang2,
Chia-Wei Wang1,
Shuichi Takayama2,
Christian M. Lastoskie2,3,
Florence I. M. Thomas5 and
Ann Marie Sastry1,2,4,*
1 Department of Mechanical Engineering, University of Michigan, Ann Arbor,
48109 MI, USA
2 Department of Biomedical Engineering, University of Michigan, Ann Arbor,
48109 MI, USA
3 Department of Civil and Environmental Engineering and University of
Michigan, Ann Arbor, 48109 MI, USA
4 Department of Materials Science and Engineering, University of Michigan,
Ann Arbor, 48109 MI, USA
5 Hawaii Institute of Marine Biology, University of Hawaii at Manoa, HI,
USA
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Fig. 1. The PDMS diffusion device, with dimensions, showing the chemochamber
(reservoir), the migration channel and the sperm chamber (reservoir). Boundary
and initial conditions used to solve the 1D diffusion equation (see Materials
and methods) are also shown.
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Fig. 2. Schematic of highly motile (A) and bulk (B) sperm in the migration channel.
(A) The situation immediately after sperm injection in the sperm chamber.
After  1.5–3 min, the bulk of spermatozoa appear in the migration
channel (B). The highly motile sperm shown in A move forward and go out of the
focus view by the time bulk sperm appear in the migration channel.
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Fig. 3. An illustration of the methodology employed to estimate the diffusion
coefficient values of bulk sperm (D value). The processed image
showing diffused bulk sperm is divided into small rectangular zones (gray
rectangles) of 29.5–31.5 µm width. The average light intensity of
each rectangular zone (I value) and the location of its center along
the length of the channel (x value) are recorded. The I
values are normalized (called In values and shown in the
figure) using the intensity value of the corresponding sample
(Io value). The x values as X
coordinates and In values as Y coordinates are
supplied to the MATLAB curvefitting toolbox. The D value is obtained
by curve-fitting Eqn 6 to the
In–x data. Not all In
and x values are shown for the sake of clarity. erf, error
function.
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Fig. 4. Schematic of egg–sperm collision simulations. The egg is pinned at
the center of the domain, and spermatozoa are distributed randomly at the
beginning of the simulation. Then sperm are moved within the domain until they
collide (penetrate) the jelly coat.
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Fig. 5. The captured image (A) and processed image (B) of sperm diffusing in ASW.
The sperm sample was prepared by mixing 10 µl dry sperm in 200 µl ASW.
(C) The sperm concentration profile along the length of the channel and the
D value estimation by curve-fitting
Eqn 6. Scale bars, 500 µm.
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Fig. 6. The captured (A) and processed (B) image of sperm diffusing in 10:250
dilution jelly coat solution. The sperm sample was prepared by mixing 10 µl
dry sperm with 200 µl 10:250 dilution jelly coat solution. (C) The sperm
concentration profile along the length of the channel and D value
estimation by curve-fitting Eqn
6. Scale bars, 500 µm.
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Fig. 7. The captured image (A) and processed image (B) of sperm diffusing in 250
nmol l–1 resact solution. The sperm sample was prepared by
mixing 10 µl dry sperm with 200 µl 250 nmol l–1 resact
solution. (C) The sperm concentration profile along the length of the channel
and the D value estimation by curve-fitting
Eqn 6. Scale bars, 500 µm.
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Fig. 8. The captured image (A) and processed image (B) of sperm diffusing in 25
nmol l–1 resact solution. The sperm sample was prepared by
mixing 10 µl dry sperm with 200 µl 25 nmol l–1 resact
solution. (C) The sperm concentration profile along the length of the channel
and the D value estimation by curve-fitting
Eqn 6. Scale bars, 500 µm.
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Fig. 10. Images of sperm treated with 250 nmol l–1 resact (A) and
10:250 dilution jelly coat (B). The resact sample shows clusters of sperm,
which are absent in jelly coat sample. These images were taken immediately
after filling the microfluidic device with respective samples. Scale bars, 500
µm.
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Fig. C1. A typical image of from the sperm life experiments showing immobile sperm
among mobile ones. (A) The image captured using the CCD camera and SimplePCI.
(B) The image processed by ImageJ. The sperm dilution for this image was
40x and hence the sperm clusters are visible in both the images.
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Fig. C2. The fraction of immobile sperm shown as a function of time. (A–C)
These three graphs were obtained for sperm from three sea urchins (shown
separately in A, B and C). The fraction of immobile sperm is shown for both
the sperm dilutions, 40x and 400x. The data for all sperm samples
studied for the sperm life experiments are shown in these figures.
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© The Company of Biologists Ltd 2007
,
where tsim is the simulation time (1800 s) and
egg is the egg diameter. The normalized collision times are
the ratio of time required for 10/30 highly motile sperm to collide the egg,
to the simulation time. The values along y-axis are the average
collision time values. (B) The bulk sperm–egg collision data. The
normalized sperm diffusion coefficient values are obtained using
,
where tsim is the simulation time (1800 s) and
