Misalignment between the magnetic dipole moment and the cell axis in the magnetotactic bacterium Magnetospirillum magneticum AMB-1
Misalignment between the magnetic dipole moment and the cell axis in the magnetotactic bacterium Magnetospirillum magneticum AMB-1
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趋磁细菌磁螺菌 AMB-1 中磁偶极矩与细胞轴之间的错位
DOI：
10.1088/1478-3975/ab2858
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发表时间：
2019
期刊：
影响因子：
2
通讯作者：
C. Fradin
中科院分区：
文献类型：
--
作者：
Lucas Le Nagard;Liu Yu;Murtuza Rajkotwala;Solomon Barkley;D. Bazylinski;A. Hitchcock;C. Fradin
虽然大多数对趋磁细菌运动的定量研究都依赖于细胞的磁偶极矩与其运动方向一致的前提，但这一假设迄今为止很少受到质疑。在这里，我们使用相衬显微镜检测的非运动细胞的磁AMB-1周围的磁矩的旋转扩散，显示在这个物种的磁偶极矩，事实上，不完全对齐与细胞体轴。从细胞旋转轨迹，我们能够推断出细胞磁矩和体轴之间的偏差，精度优于1°，表明它平均为6°，可以高达20°。我们提出了一种方法来纠正这种错位，并进行无偏测量的基础上分析其取向分布的单细胞的磁矩。使用这种校正，我们表明，磁矩强烈相关的细胞长度。在一个种群中，磁矩和细胞轴之间存在一系列的错位，这意味着置于外部磁场中的趋磁细菌的方向和轨迹比通常假设的要复杂得多，并且可能显示出一些重要的细胞与细胞之间的差异。
While most quantitative studies of the motion of magnetotactic bacteria rely on the premise that the cells’ magnetic dipole moment is aligned with their direction of motility, this assumption has so far rarely been challenged. Here we use phase contrast microscopy to detect the rotational diffusion of non-motile cells of Magnetospirillum magneticum AMB-1 around their magnetic moment, showing that in this species the magnetic dipole moment is, in fact, not exactly aligned with the cell body axis. From the cell rotational trajectories, we are able to infer the misalignment between cell magnetic moment and body axis with a precision of better than 1°, showing that it is, on average, 6°, and can be as high as 20°. We propose a method to correct for this misalignment, and perform a non-biased measurement of the magnetic moment of single cells based on the analysis of their orientation distribution. Using this correction, we show that magnetic moment strongly correlates with cell length. The existence of a range of misalignments between magnetic moment and cell axis in a population implies that the orientation and trajectories of magnetotactic bacteria placed in external magnetic fields is more complex than generally assumed, and might show some important cell-to-cell differences.