Elastic and piezoelectric properties of microtubules
The elasticity of microtubules is another issue of physical relevance, which has
been of recent theoretical and experimental interest. Using Gittes procedure
(Gittes et al., 1993) to determine flexural rigidity, Mickey & Howard (1995)
determined the Young's modulus of microtubules to be E=1.4 GPa. The value of
Young's modulus increases almost three-fold under the stabilizing action of
MAP-tau or taxol. The knowledge of this value allowed Sirenko et al. (1996) to
model the vibrations of microtubule within a fluid. They found that the microtubule
within water can support interface elastic waves with frequencies up to the
gigahertz range and that acoustic waves with velocities from 200 to 600 m/s are
possible.
Another interesting feature of microtubules is that they could have piezoelectric
properties (Athenstaedt, 1974). The word piezo is Greek for "push". Crystals,
which acquire a charge when compressed, twisted or distorted, are said to be
piezoelectric. This provides a convenient transducer effect between electrical and
mechanical (elastic) oscillations. The reverse phenomenon is also observed: if an
electrical oscillation is applied to piezoelectric crystal, it will respond with
mechanical vibrations. The biological importance of the piezoelectric effect in
microtubules remains to be assessed.
Discussion
The local electric and magnetic field strengths were assessed to be varying from
0.01 V/m to 10 V/m for the electric intensity and from 10-10 to 10-7 T for the
magnetic flux density. This rules out the possibility for the local magnetic field to
input sensory information to tubulins. We have seen that if microtubules are
intimately linked to our “consciousness” then they should have developed
mechanisms for inputting the information carried by the local electric field.
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