2026-05-28 マックス・プランク研究所
Pigeon liver tissue showing iron-containing macrophages (blue). © Lisowski et al. (2026) Science
＜関連情報＞
- https://www.mpg.de/26511515/pigeons-navigate-using-magnetic-sensors-in-their-livers
- https://www.science.org/doi/10.1126/science.aeh9507
暗闇の中を帰宅する
昼光とは無関係な2つのメカニズムによって、ハトは地球の磁場を利用して方向を定めることができる可能性がある
Getting home in the dark
Two mechanisms, independent of daylight, may enable pigeons to navigate using Earth’s magnetic field
Simon Spiro and Hal Drakesmith
Science Published:28 May 2026
DOI:https://doi.org/10.1126/science.aeh9507
Multiple animal species—including certain fish, birds, and sea turtles—can detect Earth’s magnetic field and use it for navigation. However, the anatomical sites and molecular processes enabling this magnetoreception are hotly debated. On page 985 of this issue, Lisowski et al. (1) report that certain immune cells in the liver of one species of magnetoreceptive bird, the pigeon (Columba livia), can sense alignment to Earth’s geomagnetic field and may transmit this information to the brain through afferent nerves. Other recent work by Nordmann et al. (2) also uses pigeons to identify specific regions in the brain that are activated by magnetic stimuli and suggests that the location of the putative magnetosensing cells is in the ear. Could more than one mechanism be at work?
Three prevailing hypotheses exist for how animals sense Earth’s geomagnetic field (3, 4): mechanically, through a compass-like pull on magnetic particles that is possibly associated with the trigeminal nerve (a large cranial nerve); biologically, by voltage-sensitive ion channels in cells that are activated by changes in the magnetic field; or through physical effects on retinal pigments that enable efficient detection of photons and signaling to the brain, although this can only operate in light. Each has supportive evidence, but none are universally considered to provide a full explanation of the phenomenon (5).
Lisowski et al. built on previous work (6) that reported white blood cells called macrophages as superparamagnetic because of their role in engulfing (phagocytosing) senescent red blood cells. Red blood cells contain iron, and superparamagnetism is found in small iron-containing particles that exhibit strong magnetization when exposed to an external magnetic field (7). Hypothesizing that such particles—likely the iron-storage protein ferritin—could be used for magnetoreception, Lisowski et al. screened a range of pigeon tissues for superparamagnetic properties using vibrating sample magnetometry. The liver and spleen gave the strongest magnetization signal, with minor signals in muscle and beak. A subpopulation of superparamagnetic cells could be isolated simply by passing liver-cell suspensions through magnetic columns. Prussian blue histological staining (which marks hemosiderin, a ferritin degradation product) confirmed the presence of iron-containing cells in the liver. The identity of these cells as macrophages was supported by several lines of evidence, including the presence of major histocompatibility complex class II (MHC II), a cell-surface glycoprotein expressed by macrophages.
