Systems Biomechanics of the Cell - Systems Biomechanics of the Cell - page 45

Fig. 25 Oscillations of the
lymphocyte centrosome at the
immunological synapse.
( a ) Model cell structure
plotted as in Fig. 24 . ( b )
Oscillating microtubule
system shown in projection
onto the synaptic plane. The
parts that are in contact with
the synaptic surface and are
experiencing the pulling are
highlighted. Reproduced
from Kim and Maly ( 2009 )
under the Creative Commons
Attribution License
developed theoretical concepts led Kim and Maly ( 2009 ) to develop a new model.
Elimination of the load-induced disengagement as an a-priori assumption led to the
demonstration of its effective emergence on the cellular level from the large defor-
mations of microtubules against the cytoplasmic viscous drag.
The construction of the Kim-Maly model for the cell-body movement in lym-
phocytes was discussed in the previous section. In the simulation of large-angle
reorientation of the cell body (Fig. 24 ), the emergence of pulse-like oscillations
could already be noticed. By analyzing further the mechanism of this instability, it
was found that oscillations develop in the model even if the synapse is formed next
to the initial location of the centrosome. Engagement of the microtubules with the
pulling surface causes the model centrosome to move past (or away from) the center
point of the interface. Although this point is the position of symmetry for the centro-
some, the complete symmetry of the system in general does not develop, or cannot
be sustained, in this dynamic model. The centrifugal movement of the centrosome
eventually stops, and it begins the reverse motion, again approaching the center
point and again overshooting (Fig. 25 ). The oscillations persist without noticeable