Verification of quantum biological predictions for weak magnetic field effects on superoxide in planarians.

The dependence of superoxide concentration and tissue regeneration on weak magnetic field strength in planarians exhibits a nonmonotonic behavior that classical physics struggles to explain. Here, we experimentally verify the predictions of a simple radical pair (RP) model for magnetic field modulation of superoxide levels during planarian regeneration. The model predicted increased superoxide concentrations at both hypomagnetic and higher fields (>500 µT). Previously reported magnetic field effects on blastema size do not follow the same pattern as our predictions for superoxide levels, while in earlier experiments blastema size was correlated with superoxide levels within a narrower magnetic field range (200 and 500 µT). Surprisingly, our experiments confirmed the model's predictions. We also performed a search over the parameter space of a more general RP model and identified multiple parameter sets that produce magnetic field profiles consistent with the observed ranges of superoxide levels. While the precise relationship between blastema size and superoxide concentration is evidently more complex than previously thought, and important biochemical aspects-including the identities of the radicals involved-remain to be determined, our findings support a general RP hypothesis and bolster the case for a quantum-biological explanation for these magnetic field effects.