No evidence for a magnetite-based magnetoreceptor in the lagena of pigeons

• Published in: Current biology 2019-01, Vol.29 (1), p.R14-R15
• Main Authors: Malkemper, E. Pascal, Kagerbauer, Daniel, Ushakova, Lyubov, Nimpf, Simon, Pichler, Paul, Treiber, Christoph D., de Jonge, Martin, Shaw, Jeremy, Keays, David A.
• Format: Article
• Language: English
• Subjects: Animals; Columbidae - physiology; Ferrosoferric Oxide - chemistry; Homing Behavior; Orientation; Saccule and Utricle - physiology
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2018.11.032

It is well established that an array of avian species sense the Earth’s magnetic field and use this information for orientation and navigation. While the existence of a magnetic sense can no longer be disputed, the underlying cellular and biophysical basis remains unknown. It has been proposed that pigeons exploit a magnetoreceptor based on magnetite crystals (Fe3O4) that are located within the lagena [1], a sensory epithelium of the inner ear. It has been hypothesised that these magnetic crystals form a bed of otoconia that stimulate hair cells transducing magnetic information into a neuronal impulse. We performed a systematic high-sensitivity screen for iron in the pigeon lagena using synchrotron X-ray fluorescence microscopy coupled with the analysis of serial sections by transmission electron microscopy. We find no evidence for extracellular magnetic otoconia or intracellular magnetite crystals, suggesting that if an inner ear magnetic sensor does exist it relies on a different biophysical mechanism. It has been proposed that pigeons exploit a magnetoreceptor based on magnetite crystals in the inner ear lagena. Malkemper et al. searched for these crystals exploiting X-ray fluorescence microscopy but find no evidence supporting their existence.