physarum
IB-physarum-ca-inhibits
In Physarum actomyosin, Ca2+ INHIBITS contraction — the opposite sign to animal striated muscle — and intracellular Ca2+ oscillates near-antiphase with tube radius.
Observed quantities
Ca2+-inhibition sign stable across ~40 years of biochemistry; Ca2+ vs tube-radius phase relation is near-antiphase
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Primary source
- Kohama — Physarum myosin Ca2+-regulation (report gives author name only; ~40-yr literature, no year/venue specified)
- Kscheschinski, Kramar & Alim 2023 (venue unverified in report)
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Boundary of this block
Only the SIGN of Ca-regulation and the phase relation are directly measured; the closed stretch->Ca->inhibition FEEDBACK LOOP is modeled and does not yet quantitatively fit.
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Connections
Outgoing
- relates to In Physarum a stimulus self-propagates ADVECTIVELY on the cytoplasmic shuttle-streaming flow at 1-20 um/s, in the laminar regime (Reynolds number ~0.0008) — a fully CLASSICAL transport mechanism, no quantum effects required. this Ca2+ oscillator is the pump that drives the shuttle-streaming flow doing the transport
- relates to In the only directly-testable system (Physarum), body-wide contraction FAILS to globally coordinate: coordination is intermittent and slowly-modulating — wave direction reverses and amplitude drifts — which REFUTES the global standing wave. this local oscillator is exactly what fails to lock into one global wave