Meaty Stuff from Paul Nurse

The following passages struck me as particularly relevant to our work:

"The next step is difficult, as it involves the mapping of molecular
interactions and biochemical functions onto the logic modules, in effect
linking the cellular chemistry tool-kit with the logic tool-kit. The success
of this mapping will depend on whether there are sufficient regularities
between specific logic modules and specific interacting molecules, at least
at some level of probability."
"Such regularities may not exist if natural selection has recruited many
different components from the chemical tool-kit to generate specific
examples of the logic tool-kit. However, there may be sufficient
regularities to make this mapping possible."

"Dynamic signals
"Another interesting feature of logic circuits in biological systems is the
roles that temporal organization or dynamics may have. Signalling pathways
within or between cells have generally been thought of as linear sequences
that lead to on/off switches. An analogy for such a sequence is a railway
signal that results in only one of two outcomes, a stop or a go signal. If
dynamics is introduced into signalling pathways, richer behaviours can
emerge. For example, if signals are pulsed down a pathway and the changing
outputs are monitored, much more complex information can be transmitted.
A metaphor here would be the use of the Morse code and the telegraph to
communicate messages. Pulses of information sent along the telegraph
generate a code for letters and as a consequence sentences can be
communicated. This converts the same signalling pathway from a simple on/off
switch to a device that can transfer, for example, the works of Shakespeare.
It is likely that dynamics has been exploited more generally in the
evolution of biological systems for signalling purposes, allowing the
communication of more complex information."

Regards,
Ted

LifeAsLogicSystem.pdf (35.4 KB)

[From Bill Powers (2009/01.06.1055 MST)]

"Dynamic signals
"Another interesting feature of logic circuits in biological systems is the
roles that temporal organization or dynamics may have. Signalling pathways
within or between cells have generally been thought of as linear sequences
that lead to on/off switches. An analogy for such a sequence is a railway
signal that results in only one of two outcomes, a stop or a go signal. If
dynamics is introduced into signalling pathways, richer behaviours can
emerge. For example, if signals are pulsed down a pathway and the changing
outputs are monitored, much more complex information can be transmitted.
A metaphor here would be the use of the Morse code and the telegraph to
communicate messages. Pulses of information sent along the telegraph
generate a code for letters and as a consequence sentences can be
communicated. This converts the same signalling pathway from a simple on/off
switch to a device that can transfer, for example, the works of Shakespeare.
It is likely that dynamics has been exploited more generally in the
evolution of biological systems for signalling purposes, allowing the
communication of more complex information."

I don't think Nurse is familiar with electronic circuitry -- he seems to think that "logic" is the only kind of interaction possible, rather than continous analog variations. But it's nice to see cell chemistry starting to make a move into the 20th century: I'd say they have reached about 1925. Of course they lead the rest of us by a century in biochemistry.

best,

Bill P.

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At 04:16 PM 1/3/2009 -0700, Ted Cloak wrote: