Multimodal imaging reveals no evidence for magnetite-based magnetoreceptors in the mole-rat eye

Moritz, L.; Nath, K.; Walsh, E. P.; Sternberg, A.; Becher, E.; Lange, A.; Falkenberg, G.; Brueckner, D.; Diwoky, C.; Bredies, K.; Brammerloh, M.; Howard, D.; Paterson, D. J.; Medjoubi, K.; Irsen, S.; Wolf-Kuemmeth, S.; Zhang, L.; Daniel, M. M. M.; Simpson, D. A.; Begall, S.; Malkemper, E. P.

doi:10.64898/2026.04.02.715577

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bioRxiv · 10.64898/2026.04.02.715577

Multimodal imaging reveals no evidence for magnetite-based magnetoreceptors in the mole-rat eye

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Abstract

Magnetoreception, the ability to perceive the geomagnetic field, is widespread across animals. The underlying sensory mechanism remains elusive, but a long-standing hypothesis proposes single-domain magnetite linked to mechanosensitive ion channels. The Ansells mole-rat (Fukomys anselli) is a subterranean rodent with a magnetic sense, and published behavioral and histological data are consistent with magnetite-based magnetoreceptors in the cornea or retina. Here, we systematically screened for magnetite in the mole-rat eye, combining iron detection via enhanced Prussian blue staining and synchrotron X-ray fluorescence microscopy (XFM) with magnetic detection via MRI quantitative susceptibility mapping (MRI-QSM) and quantum-diamond microscopy (QDM). This revealed only a few iron particles in the retina and cornea, which predominantly overlapped with titanium or chromium, indicating a non-biogenic origin. XFM showed iron-enriched lines in the cornea, but these did not show ferrimagnetic signals. Focusing on other ocular tissues, MRI-QSM revealed the highest susceptibility in the ciliary body, where iron-rich pigmented cells were identified. A TEM-screen, however, failed to detect single-domain magnetite particles in these cells. We conclude that our high-sensitivity multimodal screen provides no evidence for magnetite-based magnetoreceptors in the mole-rat eye, suggesting that mole-rat magnetoreceptors either do not reside in the eye or are based on different physical principles.

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Moritz, L., Nath, K., Walsh, E. P., Sternberg, A., Becher, E., Lange, A., Falkenberg, G., Brueckner, D., Diwoky, C., Bredies, K., Brammerloh, M., Howard, D., Paterson, D. J., Medjoubi, K., Irsen, S., Wolf-Kuemmeth, S., Zhang, L., Daniel, M. M. M., Simpson, D. A., Begall, S., Malkemper, E. P.. 2026-04-06. Multimodal imaging reveals no evidence for magnetite-based magnetoreceptors in the mole-rat eye. https://doi.org/10.64898/2026.04.02.715577

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