1. Physics of Living Systems
  2. Neuroscience
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Physical limits to magnetogenetics

  1. Markus Meister  Is a corresponding author
  1. California Institute of Technology, United States
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Cite this article as: eLife 2016;5:e17210 doi: 10.7554/eLife.17210

Abstract

This is an analysis of how magnetic fields affect biological molecules and cells. It was prompted by a series of prominent reports regarding magnetism in biological systems. The first claims to have identified a protein complex that acts like a compass needle to guide magnetic orientation in animals (Qin et al., 2016). Two other articles report magnetic control of membrane conductance by attaching ferritin to an ion channel protein and then tugging the ferritin or heating it with a magnetic field (Stanley et al., 2015; Wheeler et al., 2016). Here I argue that these claims conflict with basic laws of physics. The discrepancies are large: from 5 to 10 log units. If the reported phenomena do in fact occur, they must have causes entirely different from the ones proposed by the authors. The paramagnetic nature of protein complexes is found to seriously limit their utility for engineering magnetically sensitive cells.

Article and author information

Author details

  1. Markus Meister

    Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
    For correspondence
    meister@caltech.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-2136-6506

Funding

No external funding was received for this work.

Reviewing Editor

  1. David E Clapham, Howard Hughes Medical Institute, Boston Children's Hospital, United States

Publication history

  1. Received: April 25, 2016
  2. Accepted: August 15, 2016
  3. Accepted Manuscript published: August 16, 2016 (version 1)
  4. Accepted Manuscript updated: August 23, 2016 (version 2)
  5. Version of Record published: September 8, 2016 (version 3)

Copyright

© 2016, Meister

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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Further reading

    1. Physics of Living Systems
    2. Neuroscience
    Polina Anikeeva, Alan Jasanoff
    Insight

    Claims that magnetic fields can be used to manipulate biological systems contradict some basic laws of physics.

    1. Physics of Living Systems
    Debasmita Mondal et al.
    Research Article Updated

    Microorganisms swimming through viscous fluids imprint their propulsion mechanisms in the flow fields they generate. Extreme confinement of these swimmers between rigid boundaries often arises in natural and technological contexts, yet measurements of their mechanics in this regime are absent. Here, we show that strongly confining the microalga Chlamydomonas between two parallel plates not only inhibits its motility through contact friction with the walls but also leads, for purely mechanical reasons, to inversion of the surrounding vortex flows. Insights from the experiment lead to a simplified theoretical description of flow fields based on a quasi-2D Brinkman approximation to the Stokes equation rather than the usual method of images. We argue that this vortex flow inversion provides the advantage of enhanced fluid mixing despite higher friction. Overall, our results offer a comprehensive framework for analyzing the collective flows of strongly confined swimmers.