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Tambov State Technical
University
Biomedical engineering
department
Avsievich T.I., Abdulkarim S.N., Proskurin S.G.
Tambov State Technical University, Russia
[email protected]
Saratov Fall Meeting 2015
Amoeboid motility is a typical example of self-oscillating waves, which are inherent for a
wide class of cells from single-celled amoeboid to cancer cells in multicellular organisms.
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Examples:
Belousov - Zhabotinsky reaction;
mechanisms in cardiac muscle contraction;
nerve impulse propagation;
activity in cells from single-celled amoeboid to
fibroblasts, leukocytes, and cancer in multicellular organisms;
amoeboid motility
Model organism to study amoeboid
motility, nonmuscle motility.
Nature of oscillators generating
plasmodium self-oscillating motility are
still unknown
P. Polycephalum plasmodium
To analyse self-oscillating motility in the isolated plasmodium strand of
plasmodium Physarum Polycephalum upon exposure to inhibitors of
cellular respiration by sign-sensitive velocity registration.
1. Registration of self-oscillating activity in plasmodium strand in normal
conditions (buffer solution) and after inhibitors treatment;
2. Spectral analysis of the time dependences obtained using sign-sensitive
laser Doppler microscope;
3. Mathematical model building describing the oscillations in the strand
plasmodium.
P. Polycephalum
potassium cyanide (KCN):
• cytochrome pathway inhibitor
• Slime mold
• Network of cylindrical bands
100-500 µm in diameter and
length up to 2 cm
• Model organism for many
studies involving amoeboid
movement and cell motility
salicylhydroxamic acid (SHAM):
• alternative oxidase inhibitor
1)inhibition of aerobic ATP synthesis
2) cessation of breathing
3)cessation the movement of protoplasm
1) Strand of plasmodium was cut out of plasmodium and placed in the buffer solution pH=7.2,
velocity time dependence V (t) was registered;
2) Strand was treated by KCN and SHAM (5 and 7 µM respectively) which leads to a cessation
the endoplasm streaming;
3) Further inhibitors were removed and strand was placed in buffer. Resuming endoplasm
motility through 10 min was recorded.
P. Polycephalum
• potassium cyanide (KCN)
• salicylhydroxamic acid (SHAM)
Laser Doppler spectroscopy
He-Ne Laser
Detector
λ=638.2 nm,
P=1-15 mW
Strand of plasmodium
with a stream of
particles inside
Results of measurements - Velocity
time dependence (20 min)
Biophysics (2014), p. 928
Doppler spectra obtained from a moving endoplasm in a strand of Physarum
Polycephalum plasmodium.
The spectra correspond to the motion at different velocities and motionless
endoplasm (V=0 µm/s).
Solid lines - Gaussian approximation (r >0.98).
Optics & Spectroscopy (2015), in press
Velocity module
registration
Sign-sensitive
registration
SPIE Proc. (2015) Vol. 9448
Short-time Fourier Transform - STFT of time dependencies (length 600 s)
0-600 s
600-1200 s
Frequency spectra of the time dependencies of endoplasmic streaming obtained by STFT in
case of velocity module (circles) registration and in an alternating mode registration (squares).
Two distinct peaks are clearly seen in
case of sign-sensitive registration only
Optics & Spectroscopy (2015), in press
Velocity module registration r≈0.46
Simulated (red solid
line) time
dependencies based
on the spectral
characteristics:
frequencies,
amplitudes and
phases, obtained from
STFT
Sign-sensitive registration r≈0.95
Optics & Spectroscopy (2015), in press
Normal conditions,
buffer solution
One half treated
by KCN and SHAM
10 min after treatment
by KCN and SHAM
Solid lines - Gaussian
approximation
ω1=0.013±0.0004 Hz
ω2=0.0254±0.0001 Hz
ω2/ω1= 1.961,
SD 1.7 %
ω1=0.0082±0.0004 Hz
ω2=0.0161±0.00009 Hz
ω2/ω1= 2.008,
SD 2 %
ω1=0.0198±0.0004 Hz
ω2=0.0388±0.0013 Hz
ω2/ω1= 1.963,
SD 1.8 %
Biophysics (2015), submitted
Analytical calculation of the self-oscillation frequencies of harmonics:

E (0,5k1  k2  k4 )

16  l 
 
rh  n 
2
 k4 (0,5k1  k2 )
where E - Young's modulus of ectoplasm, k1, k2, k4 - rate constants, n - harmonic
number, l, r – length and radius of the strand, μ – endoplasm viscosity [2].
Theoretical frequencies:
ω1=0.0191 Hz,
ω2=0.0123 Hz
ω1/ω2=1.6
The corresponding simulated (blue solid line) time dependencies based on the spectral
characteristics: frequencies, amplitudes and phases, obtained from STFT.
Significant correlation (r≈0.95) between experimental and simulated data is observed.
Normal conditions,
buffer solution
One half treated
by KCN and SHAM
Biophysics (2015), submitted
1 harmonic ω1
appearance of a second
harmonic ω2
Harmonic oscillator with ω1 is still active after treatment – no movement is registered.
Activity recovering of the second oscillator with ω2 means that endoplasm is moving
again.
Biophysics (2015), submitted
1) STFT of velocity time dependencies allows obtaining two distinct harmonic
components in both signals.
2) The ratio of obtained frequencies with good accuracy equal to two and
remains constant in all measurements, regardless the KCN+SHAM
treatment. This indicates the presence of an internal oscillator, which
frequency is doubled and shifted in phase, or the two types of oscillators
whose frequencies differ by the factor of two.
3) Influence of KCN and SHAM leads to a complete cessation of endoplasmic
motility. After removal of the inhibitors the respiratory system becomes
normal, gradually restoring the activity of both harmonic oscillation
sources.
4) Significant correlation between mathematical model and experimental data
were demonstrated, no less than r=0.95.
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3)
4)
S.G. Proskurin, T.I. Avsievich. Spectral analysis of self-oscillating motility
in an isolated plasmodial strand of Physarum polycephalum //
Biophysics, 2014, Vol. 59, No. 6, pp. 1143–1150.
T. I. Avsievich, K. E. S. Ghaleb, S. V. Frolov, S. G. Proskurin Endoplasmic
motility spectral characteristics in plasmodium of Physarum
polycephalum // Proceedings of SPIE, 2015, Vol. 9448, p. 94480H.
Avsievich T.I., Frolov S.V., Proskurin S.G., Spectral characteristics of
shuttle self-oscillating endoplasmic motility in slime mold plasmodium
// Optics and Spectroscopy, 2015 (in press)
Avsievich T.I., Frolov S.V., Proskurin S.G., Influence of respiration
inhibitors on self-oscillating motility of Physarum polycephalum
plasmodium // Biophysics, 2015 (submitted)