You will be presented with the abstract, introduction, and discussion section from a biomedical research article. Your task is to create a summary that a layperson can understand, capturing the essence of the research article. Keep essential scientific terms, but ensure that the language remains clear and the concepts are explained in an uncomplicated manner.

Title: Physical limits to magnetogenetics}
Article:
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.
Introduction:
There has been renewed interest recently in the effects of magnetic fields on biological cells. On the one hand we have the old puzzle of magnetosensation: How do organisms sense the Earth’s magnetic field for the purpose of navigation? The biophysical basis for this ability is for the most part unresolved. On the other hand lies the promise of 'magnetogenetics': the dream of making neurons and other cells responsive to magnetic fields for the purpose of controlling their activity with ease. The two are closely linked, because uncovering Nature’s method for magnetosensation can point the way to effectively engineering magnetogenetics. The physical laws by which magnetic fields act on matter are taught to science students in college( Feynman et al., 1963). Obviously those principles impose some constraints on what biological mechanisms are plausible candidates, for both magnetosensation and magnetogenetics. A recent spate of high-profile articles has put forward audacious proposals in this domain without any attempt at such reality checks. My goal here is to offer some calculations as a supplement to those articles, which makes them appear in a rather different light. These arguments should also help in evaluating future hypotheses and in engineering new molecular tools.
Discussion:
The calculations presented here evaluate the mechanisms that might underlie recent observations on a molecular compass( Qin et al., 2016) and neural activation with static magnetic fields( Wheeler et al., 2016) or high-frequency magnetic fields( Stanley et al., 2015). These calculations show that none of the biophysical schemes proposed in these articles is even remotely plausible, and a few additional proposals were eliminated along the way. The forces or torques or temperatures they produce are too small by many orders of magnitude for the desired effects on molecular orientation or on membrane channels. If the phenomena occurred as described, they must rely on some entirely different mechanism. Barring dramatic new discoveries about the structure of biological matter, the proposed routes to magnetogenetics, based on either pulling or heating a ferritin/channel complex with magnetic fields, have no chance of success. One does have to ask why none of these authors attempted a back-of-the-envelope estimate to bolster the claims in their papers. Neither, it seems, did the referees who reviewed the manuscripts, nor the authors of three pieces that heralded these articles( Leibiger and Berggren, 2015; Lewis, 2016; Lohmann, 2016). Why is it important to do so? First of all, claims that violate the known laws of physics often turn out to be wrong( Maddox et al., 1988). There is, of course, always a small chance of discovering new physics, but only if one understands what the old physics predicts and recognizes the discrepancy. If any of the claims in these articles were substantiated – a room-temperature molecular magnet or measurable forces and heating from ferritin – their implications for our basic understanding of nanoscale matter would far outweigh their biological significance. More importantly though, calculations are most useful when done ahead of time, to guide the design of experiments. For example, Stanley et al.( 2015) and Wheeler et al.( 2016) evoke an image in which the magnetic field pulls on the ferritin particles. This is possible only if the magnetic field has a strong gradient( Figure 1a, Equation 10). None of their experiments on animals were designed to produce a strong gradient, nor do the articles report what it was. It is in fact possible to pull on cells that express lots of ferritin, and this has been exploited for magnetic separation( Owen and Lindsay, 1983). It requires very high magnetic fields, and separation columns with a meshwork of fine steel fibers that produce strong gradients on a microscopic scale. Inserting such a wire mesh into the brain would of course negate the goal of non-invasive control. Two other hypothetical mechanisms for the ferritin effects require a strong field but no gradient. This would be of great experimental value, because a homogeneous magnetic field could then deliver the same control signal throughout an extended volume, like the brain of a mouse. Among these, the dipole interaction between ferritins( Figure 1b, Equation 14) offers little hope. Even with a 100-fold larger field( 5 T), these forces are still 4 log units too small to open a channel. That field strength represents a practical limit: Small movements of the animal, or switching of the field, will cause inductive eddy currents that activate the brain non-specifically, a phenomenon experienced also by MRI subjects( Schenck et al., 1992). On the other hand, exploiting anisotropy of the ferritin particle( Figure 1c, Equation 15) may be within range of utility. A 100-fold larger field could produce torque comparable with the thermal energy, which when applied to thousands of channels might have a noticeable effect on membrane currents. To enhance the shape anisotropy of the magnetic particles, perhaps one could engineer the ferritin shell into an elongated shape. More fundamentally, it is clear that the weak effects computed here are a consequence of ferritin’s paramagnetism. A particle with a permanent magnetic moment, such as the magnetosomes made by bacteria( Bazylinski and Frankel, 2004), could exert much larger forces, torques, and temperatures( Hergt et al., 2006), and may offer a physically realistic route to magnetogenetics. With an eye towards such future developments, it is unfortunate that these three questionable claims were published, especially in high-profile journals, because that discourages further innovation. Now that the prize for magnetogenetics has seemingly been taken, what motivates a young scientist to focus on solving the problem for real? There is an important function here for post-publication peer review: It can make up for pre-publication failures and thus reopen the claimed intellectual space for future pioneers.
How biological systems interact with magnetic fields is of great interest both from a basic science perspective and for technological applications . Certain animal species can sense the Earth’s magnetic field for the purposes of navigation . How that compass sense works is perhaps the last true mystery of sensory biology . If we knew how the magnetic field affects the activity of nerve cells , we could harness that mechanism to create new biomedical tools . One technological goal is to genetically engineer specific cells in the brain or elsewhere so their activity can be controlled using an external magnet . This dream has been called “magnetogenetics” . In recent months a string of reports claimed to have solved both the scientific and the technological challenges of magnetogenetics . They all involved the discovery or the engineering of protein molecules that are sensitive to magnetic fields . Markus Meister has now checked whether those claims were consistent with well-established physical laws . For each case , Meister calculated how strongly the protein in question would link magnetic fields to cellular activity . The results show that the predicted effects are too weak to account for the reported measurements by huge margins: between five and ten orders of magnitude . It therefore appears that none of these reports have hit on a solution to magnetogenetics . All of the proposed proteins use iron atoms to couple to the magnetic field , but Meister concludes that these proteins contain far too few iron atoms . How safe is that conclusion ? There has been enormous technological interest in making tiny magnets; for example , to design the ever-denser data storage drives inside computers . Hence the magnetism of small clusters of atoms is exceedingly well understood . If any of the biological reports of magnetogenetics turned out correct , they would force a revolutionary rethinking of basic physics . With the recognition that magnetogenetics remains unsolved , and that different approaches are needed , Meister hopes that other investigators will feel motivated to continue innovating in this area .