ULTIMATE COMPUTING - Quantum Consciousness Studies

Cytoskeleton/Cytocomputer 93
and overall cell polarity. How can a peripheral clue lead to reorganization deep in
the cell One possible explanation is that a signal is relayed through the
cytoskeleton to the MTOC, leading to a change in its orientation and directed
nucleation of microtubules. Another is that a signal at the periphery affects the
MT distribution directly. Since the entire cytoskeletal array is dynamic, it might
only be necessary to transiently stabilize a particular subset of microtubules for
the cellular cytoskeletal array to rapidly transform. Kirschner and Mitchison
(1986) have proposed that the dynamic microtubule array probes many regions at
random. By stabilizing certain MT configurations as they arise, they believe the
cell can arrive at a structure that is not precisely defined by genetic information
but one that adapts to fulfill a particular functional role.
Dynamic structural rearrangement of the MT cytoskeleton appears to require
intelligence. Like the brain as a whole, cytoskeletal intelligence has features of
connectionism, parallelism, distributedness, and hierarchy. The apparent
cytoskeletal commanders are MTOC, of which the critical structures are the
organelles which may have hijacked evolution: centrioles.
5.2.3 Microtubule Organizing Centers (MTOC) and
Centrioles
MTOC and their chief components, centrioles, are the specific apparatus
within living cells which trigger and guide reorganization of cytoplasm such as
occurs during growth, generation of form and function (“differentiation”) and cell
movement. The enigmatic MTOC determine where, when, and how these
functions occur (Figure 5.11).
MTOC (or “centrosomes”) contain centrioles and “pericentriolar substance”
which facilitates tubulin assembly by somehow lowering Cc. Centrioles are the
common structure in all of these cellular control centers. Centrioles are composed
of two similar cylinders; their diameters are 0.2 microns or 200 nanometers. Each
cylinder possesses a 9 fold radial symmetry and is constructed essentially of 9
triplets of microtubules fused longitudinally. “Satellites,” electron dense proteins,
appear to orbit the centrioles. A cartwheel filamentous structure (“pinwheel”)
connects all the microtubules within each centriole at one end. One centriole
begets another by replication perpendicular to the cylindrical surface of the
centriole. The first step in cell division is maturation of the “mother” cell,
followed by separation of pairs of centrioles and migration to establish
architecture of “daughter” cells. Centriole mechanisms of perpendicular
replication, orientation and guidance are unknown.