ULTIMATE COMPUTING - Quantum Consciousness Studies

158 Models of Cytoskeletal Computing
and occurs if the distance between the chromophores is relatively close, not to
exceed about 10 nanometers. In the study by Becker, Oliver, and Berlin,
fluorescein isothiocyanate (FITC) was used to fluorescently label one population
of unpolymerized MT subunits or membranes, and another fluorescent label,
rhodamine isothiocyanate (RITC) was used to label a second population of
tubulin. They chose these chromophores because they bind covalently to tubulin
or membranes, and because the emission spectrum of FITC “donors” extensively
overlaps the absorption spectrum of RITC acceptors. Recordings of fluorescence
spectra reveal the “resonance transfer” when it occurs. When MT were
depolymerized, a mixture of donor labeled and acceptor labeled tubulin did not
show resonance transfer. With polymerization or aggregation of MT subunits,
fluorescent excitation of fluorescein labeled tubulin resulted in fluorescent
emission by rhodamine labeled tubulin, as the chromophores were brought
sufficiently close together in a common lattice to permit resonance energy
transfer. The energy transfer occurred not only among tubulin subunits in MT, but
among MT subunits and membrane components.
Evidence for another mode with communicative implications in microtubules
is suggested by the parallel alignment of MT in applied electric and magnetic
fields (Vassilev, Dronzine, Vassileva, and Georgiev, 1982). They cite the
postulated existence of low intensity electric fields (Jaffe and Nuccitelli, 1977;
Adey, 1975) in the range of 20 to 500 millivolts per centimeter within cells (one
millionth of the field strength across polarized membranes). Vassilev and
colleagues isolated rat brain tubulin and created polymerizing conditions in the
presence of pulsed electric fields of about 25 millivolts per centimeter. Electron
micrographs showed that the MT polymerized in perfect parallel alignment with
the applied field. Similar results were obtained when low intensity (0.02 Tesla)
magnetic fields were applied. If assemblies of MT can also generate electric
and/or magnetic fields of similar intensity via an electret effect, then a cooperative
communication comparable to the “Indian rope trick” may be utilized in cellular
growth, differentiation, and synaptic plasticity. MT could then generate their own
pathways for cytoplasmic movement.
Other data (Matsumoto and Sakai, 1979; Alvarez and Ramirez, 1979) suggest
that the intraneuronal cytoskeleton is necessary for nerve membrane excitability
and synaptic transmission. Nerve membrane proteins including ion channels and
receptors which are anchored to the cytoskeleton may be the “tips of an iceberg”
of a cytoskeletal communicative medium which could utilize a number of
possible modes to achieve collective cooperativity and intelligent cellular
behavior. The following models suggest some possible strategies.
8.2 Cytoskeletal Information Processing
The following models have been roughly grouped by authors and significant
concepts.
8.2.1 MT Sensory Transduction/Atema
Several authors have discussed the transduction of sensory information by the
mechanical distortion of cilia: membrane covered centriole-like structures which
protude from cells. Lowenstein, Osborne, and Warshall (1964) suggested that the
“kinocilium” of the hair cells in the inner ear served as motile cilia in reverse.
They reasoned that motile cilia produced movement using chemical energy
provided by ATP hydrolysis, so mechanoreceptor cilia should transduce
mechanical deformation caused by environmental stimuli to provide the cell with
“patterns of chemical energy representing information.” Lettvin and Gestalind