动物地磁导航机制研究进展

Progresses in the Mechanisms of Animal Geomagnetic Navigation

地磁场是地球重要的物理场,它不仅能保护地球生物免受太阳风及其他宇宙射线的伤害,阻挡地球生命赖以生存的大气圈和水圈被剥蚀,为地球生物提供一个温和的生存进化环境,而且其强度、偏角和倾角能为动物迁徙提供定位导航参考。目前,行为学研究已经发现许多鸟类、爬行类、两栖类、哺乳类等动物都能够利用地磁场导航。动物感知地磁场的磁感受器(magnetoreceptor)、磁信息的感知机制和信号传递通路一直是动物地磁导航研究的焦点和难点,但目前对它们的了解并不十分清楚。基于国内外学者最近的研究成果,本文首先介绍三种主要的磁感知机制及其相应的证据:电磁感应、基于光受体的磁感知及基于磁铁矿纳米颗粒的磁感知。其次,总结鸟类基于光受体和磁铁矿纳米颗粒的磁感知神经通路和相应的磁信息响应脑区:(1)眼睛视网膜上光依赖的磁感受器——隐花色素通过视觉通路与大脑联系获取准确方向信息;(2)上喙或内耳中的磁铁矿纳米颗粒磁感受器,通过三叉神经或内耳听壶传入神经将感知的磁场强度信息传至脑干前庭区域,获得"导航图"信息。最后,简要总结近年来哺乳动物地磁导航的研究进展,并指出动物地磁导航研究当前亟待解决的几个重要科学问题。

Geomagnetic field （GMF） is an important geophysical field of the planet Earth. It is the field that shields organisms from the solar wind and other cosmic rays, and plays an important role in protecting the atmosphere and hydrosphere escape from earth which are crucial to life survival to provide a mild survival habitability of our planet planet. Besides, it is widely recognized that the intensity, declination and inclination of the GMF can provide navigational reference information for animals during their migration. It has been found that diverse animals, including birds, reptiles, amphibians, mammals and other animals, can use the GFM for orientation and navigation. However, the magnetoreceptor which allows an organism to detect the magnetic field, the mechanisms of magnetoreception and the related neural pathway of magnetoreception is still largely unknown. In this review, we describe three major well-known magnetoreception mechanisms and their corresponding evidence： （1） Electromagnetic-induction-based magnetoreception; （2） Photoreceptor-based magnetoreception; and （3） Magnetite-based magnetoreception. The magnetoreception neural pathways and brain regions involved in magnetic information processing of mechanism （2） and （3） in birds will be discussed： the photoreceptor-cryptochrome in retina which obtains the direction of geomagnetic field can transmit the magnetic information to brain through visual pathway to acquire direction information; and the magnetite receptors, based on nanoparticles of magnetite either in the skin of upper beak or/and inner ear lagena of avian which transmitted the magnetic strength information to brainstem neurons through trigeminal nerve/lagena afferent terminations as a part of the ＂navigational map＇ to obtain positional information. We also summarized the recent progresses on mammals geomagnetic navigation and raised some key scientific issues in the further researches on animal geomagnetic navigation.