单畴磁铁矿磁接收器磁学模型

The magnetic model of the single-domain magnetite magnetoreception

很多生物可以利用地磁场辨别方向和方位,而生物磁铁矿被广泛发现存在于这些生物体中,研究者认为,生物磁铁矿与周围组织(包括神经组织)构成磁接收器,它在与外界磁场的相互作用中,将外界磁场信息转化成神经信息促使生物作出相应的反应;生物磁铁矿磁接收器理论包括单畴磁铁矿磁接收器模型和超顺磁磁铁矿磁接收器模型;趋磁细菌体内存在典型的单畴磁铁矿颗粒,本文中,以趋磁细菌为例,从磁学理论角度出发,定性的探讨了单畴磁铁矿磁接收器的磁学模型和工作机制:在外磁场中,外面包围着生物膜的单畴晶体会受到力的作用,单畴晶体把力转加给生物膜,再被生物膜中的机械感受器接收到,再转变为刺激信号,引起细胞相应的运动行为;或者是,磁铁矿粒子通过与生物膜的结合,把受到的力转变为打开或关闭离子通道,影响离子的流入,跨膜电势发生改变,从而产生刺激信号;多个单畴晶体及膜的存在会导致信号的增加与放大.

Many living beings can distinguish direction and position by using geomagnetic field, while biomagnetites can be found in these living beings, so scholars think that there are magnetoreceptions existing in these living beings which are formed by the biomagnetites and outer organic tissues （including the nerve）. The magnetoreceptions in- teract with outer magnetic field and can transform the magnetic information into neural information, so these living beings can have response to it. The theories of biomagnetite magnetoreceptions include the model of single-domain magnetite magnetoreception and the model of superparamagnetic magnetite m_agnetoreception~ In magnetotactic bac- teria, there are many typical single-domain magnetites, so in this paper, the magnetic model and working mecha- nism of the single-domain magnetite magnetoreception are discussed qualitatively from the point of view of theory of magnetism taking the example of magnetotactic bacteria. In the outer magnetic field, each single-domain magnetite which is surround by biomembrane can be forced, and the single-domain magnetite transmits the force to the outer biomembrane and can be accepted by mechanical receptor in the biomembrane, then the force can be transformed in- to a stimulus signal which can cause the behavior of the bacteria. Another case may also exist, the single-domain magnetites combine with the biomembrane tightly, the force can open or close the ion passageway thereby influen- cing the inflow of ions and influencing the transmembrane potential, so stimulus signal can be produced. The sig- nals can be magnified because many single-domain magnetites and biomembrane exist.