| 研究課題/領域番号 |
20H02687
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| 研究機関 | 東京大学 |
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研究代表者 |
ウッドワード ジョナサン 東京大学, 大学院総合文化研究科, 教授 (80526054)
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| 研究期間 (年度) |
2020-04-01 – 2023-03-31
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| キーワード | 磁気受容 / 細胞の自家蛍光 / ラジカル反応 / 磁場効果 / 発光分析 / スピン化学 |
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| 研究実績の概要 |
During the first year of the project the work undertaken was focused in two main areas:
Instrument development: A ccd based UV/vis spectrometer was purchased and installed in our fluorescence microscope system. Custum software was written to control timed spectral capture from a focussed camera selected image.
Multiple supercontinuum (SC) light sources were loaned from a manufacturer and tested extensively in the TOAD microscope. Pulse-to-pulse reproducibility was determined to be too low for use in our TOAD microscope with the necessary sensitivity for investigating radical pair photochemistry. A new approach was developed using multiple CW lasers and an appropriate set of lasers and optics were purchased and delivered at the end of the first year.
Investigations of the magnetic field dependence of natural cellular photochemistry: Magnetic field effects on cellular autofluorescence were observed for the first time. Work began with optimisation of the fluorescence microscope system for this particular type of sample. After magnetic field responses were observed, extensive testing was undertaken to eliminate any possibility that the observed effects were artefactual. This included eliminating all possibility of sample heating or the influence of magnetic field generation on other instrumentation. The spectral and magnetic responses were studied in detail and a new convolution method to compensate for slow photochemistry was developed. The results were reported in the journal Proceedings of the National Academy of Sciences (PNAS). The work received substantial media coverage.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
Major progress was made in the investigation of the magnetic field dependence
of natural cellular photochemistry. Magnetic field responses were observed directly on the weak autofluorescence from HeLa cells at physiological pH. Characterisation of the spectral and magnetic responses concluded that the signals arose from radical pair based flavin photochemistry in the mitochondria. This is the first time that radical pair chemistry and spin effects have been observed in native, living cells.
One of the main goals for year one of the project was to convert our TOAD microscope to a supercontinuum (SC) based probe light source to allow spectral discrimination. Disappointingly, this approach was revealed to be impossible on the basis of extensive testing of instruments borrowed from the manufacturer. While published specifications of commercial SC sources are impressive, manufacturers never publish data on the shot-to-shot power stability. Our detailed testing revealed this to be very poor. As a consequence, it is impossible to use such a source as a direct probe pulse in our TOAD measurements and achieve the necessary sensitivity levels to monitor radical pair photochemistry in sub-cellular volumes at realistic concentrations. Therefore, we needed to develop an entirely new approach exploiting multiple highly stable single wavelength solid-state CW lasers, which combined can cover the useful spectral range necessary to characterise flavin photochemistry. We thus purchased such lasers and accompanying optics instead of the originally proposed SC source and wavelength separator.
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| 今後の研究の推進方策 |
Instrument development: Different optical arrangements for the new multiple diode laser system will be tested and the best approach adopted. The system will then be installed in the TOAD microscope system, followed by extensive testing, optimization and characterization using model chemical systems of flavin photochemistry. Operating software will be written and tested.
Investigations of the magnetic field dependence of natural cellular photochemistry: Measurements on cellular autofluorescence will continue and will focus on testing the ubiquity of the effect in other cultured cells, the impact of cellular stress on magnetic field effect magnitude, the variation of the magnetic field sensitivity across different cellular subsystems and on developing experimental techniques to perform measurements in tissue samples.
Developing methods to study the magnetic sensitivity of proteins artificially introduced into cells: Protein expression will begin for key proteins including cryptochromes and mitochondrial flavoproteins lipoamide dehydrogenase and electron transfer flavoprotein. Experiments will then be undertaken to investigate the possibility of studying the photochemistry of these proteins directly inside the cells in which they are expressed using both optical absorption and fluorescence based microscopy.
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| 備考 |
Reported by a wide range of news sites worldwide. Reporting languages included Arabic, French, German, Croatian, Finnish, Portuguese, Spanish. A reddit article in r/science received 35000 upvotes.
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