Carmichael’s Concise Review Coming Events
Due to COVID-19, please check to see if the listed events have been postponed or cancelled.
2021
ICMCMM 2021: 15th International Conference on Macromolecular Chemistry and Molecule Microscopy
June 24–25, 2021 Oslo, Norway
https://waset.org/macromolecular-chemistry-and- molecule-microscopy-conference-in-june-2021-in-oslo
5th International Congress on 3D Materials Science (3DMS 2021) June 29–July 2, 2021 Washington, DC
www.tms.org/3DMS2021
mmc2021: Microscience Microscopy Congress 2021
July 5–8, 2021 Virtual
www.mmc-series.org.uk
Microscopy & Microanalysis 2021 August 1–5, 2021
Virtual
www.microscopy.org/events/future.cfm
MC 2021 Joint Meeting of Dreiländertagung & Multinational Congress on Microscopy
August 22–26, 2021 Virtual
www.microscopy-conference.de
2021 Gordon Research Conference on Three-Dimensional Electron Microscopy
October 31–November 5, 2021 Newry, ME
www.grc.org/three-dimensional-electron- microscopy-conference/2021
2022
Microscopy & Microanalysis 2022 July 31–August 4, 2022
Portland, OR
www.microscopy.org/events/future.cfm
2023
Microscopy & Microanalysis 2023 July 24–28, 2023
Minneapolis, MN
www.microscopy.org/events/future.cfm
2024
Microscopy & Microanalysis 2024 July 28–August 1, 2024
Cleveland, OH
www.microscopy.org/events/future.cfm
Do Bird Migration and Childhood Leukemia Have Something in Common?
Stephen W. Carmichael Mayo Clinic, Rochester, MN 55905
carmichael.stephen@
mayo.edu
It is possible that both the migration of birds (and other animals) and
childhood leukemia involve cells that are sensitive to magnetic fields. In an elegant study [1] that required the development of a unique microscope, Noboru Ikeya and Jonathan Woodward may have identified the mechanism by which cells respond to a magnetic field; this in turn could be related to both animal migration and human health. Te study of magnetic field effects on biological processes is extremely challenging since the effects are typically weak and highly variable. What was needed to convincingly demonstrate cellular magnetic field responses was a measurement in which the direct influence of the magnetic field on living cells or subcellular structures was clearly observed in real time. Ikeya and Woodward have provided this. A strong candidate for a mechanism by which cells sense magnetism is
the so-called radical pair mechanism (RPM). It has been well-established that some chemical reactions, that proceed through the formation of short- lived reaction intermediates called radical pairs (RPs), can be influenced by the application of weak magnetic fields. Indeed the key candidate molecules proposed as being responsible for the magnetic “compass” in migratory birds are blue light-photosensitive proteins called cryptochromes, which contain flavin adenine dinucleotide (FAD) and that generate RPs when photoexcited. Flavins are also one of the molecules responsible for the autofluorescence of cells. Crucial to the RPM is the ability of RPs to mix between different spin states, the efficiency of which can be altered by the application of a magnetic field. Te subsequent “spin-selective reaction” results in different fates for the RPs depending on their spin state and, thus, on the magnetic field. In this study the application of a magnetic field alters the amount of time the flavin molecules spend in a fluorescent state, resulting in a change of the observed fluorescence signal caused by their photoexcitation. Under certain circumstances, the fluorescence will decrease as the magnetic field is applied. Ikeya and Woodward chose to use HeLa cells because they are the most
extensively studied immortal human cell line. Te goal was to demonstrate that autofluorescence in these cells showed a magnetic field effect consistent with the RPM and present evidence that the source of this effect could be explained by known reactions to blue light photoexcitation. Using their unique microscope that was capable of applying a magnetic field in the low milli-tesla range directly to a cell, they showed a small but clear change in fluorescence in response to the magnetic field (Figure 1). Specifically, a decrease in autofluorescence of 1 to 2.5% was observed in real time when the magnetic field was applied. Te variation in autofluorescence change meant that the effect of the magnetic field is more clearly visible in some cells than others. Tese observations led Ikeya and Woodward to suggest that the simplest explanation is probably correct (Occam’s razor); specifically, flavin-based RPs are responsible for the observed magnetic responses in the cells.
8 doi:10.1017/S155192952100064X 2021 May
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