Biomedical engineering
Tambov State Technical University
Self-oscillating endoplasmic motility study
in a strand of plasmodium P. Polycephalum
T.I. Avsievich, S.N. Abdulkareem,
S.G. Proskurin
http://bmt.tstu.ru/
spros@tamb.ru
INTRODUCTION
Endoplasmic motility is an example of auto oscillation, which is inherent to a wide class of
cells from single-celled amoebas to cancer cells in multicellular organisms.
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•
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Examples:
Belousov - Zhabotinsky reaction;
mechanisms in cardiac muscle contraction;
nervous impulse propagation;
activity in cells from single-celled amoeboid to
fibroblasts, leukocytes and tumor cells in multicellular
organisms;
amoeboid motility
P. Polycephalum
Autowaves in Belousov
- Zhabotinsky reaction
PURPOSE of the STUDY
To analyse time-dependent velocity V(t) of self-oscillating motility of
endoplasm in the isolated strand of plasmodium Physarum Polycephalum
upon exposure to inhibitors of cellular respiration.
OBJECTIVES
1. Registration of self-oscillating motility in the strand in normal conditions
(buffer solution) and after the inhibitors’ treatment;
2. Fourier analysis of the time dependences V(t) of the endoplasm;
3. Mathematical model describing the registered oscillations.
MATERIALS and METHODS
• Slime mold
• Network of cylindrical bands
100-500 µm in diameter and
length up to 2 cm
• Model organism for many
studies involving amoeboid
motility
P. Polycephalum
potassium cyanide (KCN):
•cytochrome pathway inhibitor
salicylhydroxamic acid (SHAM):
•alternative respiration inhibitor
1) inhibition of aerobic ATP synthesis
2) cessation of breathing
3) cessation of endoplasmic motility
1) 10 mm strand was isolated out of plasmodium and placed in buffer solution pH=7.2;
2) Strand was treated with KCN and SHAM (5 and 7 µM, respectively) which leads to a cessation
of protoplasmic motility;
3)Further inhibitors were removed and strand was placed in the buffer solution. Resumption of
endoplasmic motility, V(t) recording for 10 min after.
MATERIALS and METHODS
P. Polycephalum
• potassium cyanide (KCN)
• salicylhydroxamic acid (SHAM)
Laser Doppler anemometer
Laser
Velocity time dependence
Detector
Strand of plasmodium
with shuttle
endoplasmic motility
inside
RESULTS
Spectral analysis (Fast Fourier Transform - FFT)
(length 600 s) from 0 and 600 s
Figure 1.
Fourier spectra of the time dependence V(t) of
protoplasmic motility from 0 to 600 s (blue)
and 600 to 1200 s (pink) in the buffer solution.
Figure 2.
Similar spectra after KCN and SHAM treatment
Solid lines - Gaussian approximations to the peaks
Proskurin S. G., Avsievich T. I., Biophysics, 2014 (in press)
RESULTS
Influence of inhibitors
After removal of respiratory inhibitors
ω1
• During first 10 min increases
activity of the first peak and the
complete suppression of the second
one.
ω2
• On 12th minute, system begins to
return to the normal state with two
harmonic components.
Respiratory inhibitors affect on both sources of oscillation,
but one of them (ω1) recovers faster.
Proskurin S. G., Avsievich T. I., Biophysics, 2014 (in press)
RESULTS
Buffer solution ( pH=6,8)
In buffer after treatment
by KCN and SHAM
ω1 and ω2 remains constant
during 20 min:
at first 10 min just one source of oscillations ω1 is
present, in the next 10 min noted the appearance
of a second frequency peak ω2:
ω1=0.013±0.0004 Hz
ω2=0.0254±0.0001 Hz
ω1=0.0198±0.0004 Hz
ω2=0.0388±0.0013 Hz
ω2/ω1= 1.961
SD 2.6 %
ω2/ω1= 1.963
SD 1.8 %
Spectral analysis reveals two distinct harmonic signals.
Despite the frequencies differ in first and second signals, the ratio
ω2 /ω1=1.96±2% in each of them remains constant.
RESULTS
Analytical calculation of the self-oscillation frequencies of harmonics:

E (0,5k1  k 2  k 4 )

16  l 
 
rh  n 
2
 k 4 (0,5k1  k 2 )
where E - Young's modulus of ectoplasm elasticity, 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=0.0361 Hz
ω2/ω1=1.89
RESULTS
Time dependences of endoplasmic motility in plasmodium strand before (a)
and after removing the respiration inhibitors (b)
a)
R2=0.943
b)
Significant correlation
between the model and
experimental data is
observed
R2=0.971
RESULTS
1 harmonic ω1
appearance of a second harmonic ω2
R2=0.971
Significant correlation between mathematical model and experimental data up to
800 s is observed.
Additional parameters are required to describe transition to the normal state.
RESULTS
Directed motion of endoplasm
S+
S-
Area under the graph is changed
S+ - above X axis
S– - under X axis
S+ / S - ≈ 0, 6
S+
S- S / S ≈ 1, 6
+
-
Directed motion of the strand is different for the first and the second signal
DISCUSSION and CONCLUSIONS
1) Sign-sensitive laser Doppler velocimetry allows to register shuttle
endoplasmic motility in plasmodium strands with diameter up to 0.5 mm;
2) Fourier analysis of velocity time dependences of the endoplasm allows
obtaining two distinct harmonic components in both signals;
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.
REFERENCES
1.
Proskurin S.G., Avsievich T.I., Spectral analysis of self-oscillation motility in isolated
plasmodium strand of Physarum Polycephalum // Biophysics. 2014 (in press).
2.
Teplov V.A., Mitrofanov V.V., Romanovsky Y.M., Synchronization of mechanochemical
auto-oscillations within the Physarum polycephalum plasmodium by periodical
external actions // Biophysics. 2005, T. 50, № 4. p. 704-712.
Biomedical engineering
Tambov State Technical University
Self-oscillating endoplasmic motility study
in a strand of plasmodium P. Polycephalum
T.I. Avsievich, S.N. Abdulkareem,
S.G. Proskurin
http://bmt.tstu.ru/
spros@tamb.ru