Sakata Masanobu, Kawasaki Tamami, Shibue Toshimichi, Takada Atsushi, Yoshimura Hideyuki, Namiki Hideo
Department of Integrative Bioscience and Biomedical Engineering, Waseda University, 3-4-1 Okubo, Shinjyuku-ku, Tokyo 169-8555, Japan.
Biochem Biophys Res Commun. 2006 Dec 15;351(2):566-70. doi: 10.1016/j.bbrc.2006.10.078. Epub 2006 Oct 23.
This study characterized the magnetic materials found within Daphnia resting eggs by measuring static magnetization with a superconducting quantum interference device (SQUID) magnetometer, after forming two types of conditions, each of which consists of zero-field cooling (ZFC) and field cooling (FC). Magnetic ions, such as Fe(3+), contained in Daphnia resting eggs existed as (1) paramagnetic and superparamagnetic particles, demonstrated by a magnetization and temperature dependence of the magnetic moments under an applied magnetic field after ZFC and FC, and (2) ferromagnetic particles with definite magnetic moments, the content of which was estimated to be very low, demonstrated by the Moskowitz test. Conventionally, biomagnets have been directly detected by transmission electron microscopes (TEM). As demonstrated in this study, it is possible to nondestructively detect small biomagnets by magnetization measurement, especially after two types of ZFC and FC. This nondestructive method can be applied in detecting biomagnets in complex biological organisms.
本研究通过使用超导量子干涉装置（SQUID）磁力计测量静态磁化强度，对水蚤休眠卵内发现的磁性材料进行了表征。实验形成了两种条件，每种条件均由零场冷却（ZFC）和场冷却（FC）组成。水蚤休眠卵中所含的磁性离子，如Fe(3+)，以以下两种形式存在：（1）顺磁性和超顺磁性颗粒，通过零场冷却和场冷却后在施加磁场下磁矩的磁化强度和温度依赖性得以证明；（2）具有确定磁矩的铁磁性颗粒，通过莫斯科维茨测试表明其含量估计非常低。传统上，生物磁体是通过透射电子显微镜（TEM）直接检测的。如本研究所示，通过磁化测量，特别是在两种零场冷却和场冷却之后，可以无损检测小型生物磁体。这种无损方法可应用于检测复杂生物体内的生物磁体。
