Abstract
Magnetic field effects (MFE) have been asserted to have a role in biology for several decades,
and under various mechanisms. However, the interaction mechanism by which even low
magnetic fields (MF), such as the geomagnetic field (20-60 µT), could significantly affect
biochemical reactions have remained opaque. One way by which biochemical processes could
in principle acquire sensitivity to the geomagnetic field is via the radical pair mechanism
(RPM), as exemplified the cryptochrome hypothesis of magnetoreception (Hore and
Mouritsen, 2016). Cryptochrome, the putative magnetoreceptor molecule, and its flavin
cofactor are thought to generate spin-correlated, charge-separated radical pairs. As reactive
oxygen species (ROS) are prevalent across biology, ROS generation and modulation in
response to magnetic fields may be an important (Usselman et al., 2014) and understudied
element of the whole picture of biological magnetic sensitivity. Using a constitutive model of
Drosophila CRY (DmCRY) expression in an E. coli–∆KatG strain, MFEs on ROS-based
fluorescence, specific growth rate, and associated toxicity were assessed as phenomenological
and quantitative indicators. This work also details the design and testing of non-standard
equipment for the exposure conditions used here, including double-wound Helmholtz coils
for generation of uniform MFs (and control conditions) and an illumination source that covers
electromagnetic (EM) spectrum wavelengths in the visible range, 380 to 790 nm. Additionally,
qualitative results on the FMN-photosensitised oxidation of human lysozyme, and an
MFdependence are presented in this work and serve as validating proof of the capacity for the
designed equipment in generating an MFE in a magnetically sensitive biochemical reaction.
Site-directed mutagenesis of WT DmCRY and human CRY (HsCRY2) and the viability of
these variants are also presented in this work