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Transmission electron microscopy DNA sequencing is a single-molecule sequencing technology that uses transmission electron microscopy techniques. The method was conceived and developed in the 1960s and 70s,〔 (Michael Beer and Richard Zobel (1961) "Electron stains II: Electron microscopic studies on the visibility of stained DNA molecules" J. Mol. Biol. Volume 3, Issue 6, December 1961, Pages 717–726, IN3–IN5" ) 〕 but lost favor when the extent of damage to the sample was recognized.〔 (Cole et al (1977) "Molecular microscopy of labeled polynucleotides: Stability of osmium atoms" J. Mol. Biol. Volume 117, Issue 2, 5 December 1977, Pages 387–400 )〕 In order for DNA to be clearly visualized under an electron microscope, it must be labeled with heavy atoms. In addition, specialized imaging techniques and aberration corrected optics are beneficial for obtaining the resolution required to image the labeled DNA molecule. In theory, transmission electron microscopy DNA sequencing could provide extremely long read lengths, but the issue of electron beam damage may still remain and the technology has not yet been commercially developed. ==History== Only a few years after James Watson and Francis Crick deduced the structure of DNA, and nearly two decades before Frederick Sanger published the first method for rapid DNA sequencing, Richard Feynman, an American physicist, envisioned the electron microscope as the tool that would one day allow biologists to “see the order of bases in the DNA chain”.〔Feynman R. (1959) (There’s plenty of room at the bottom ). Caltech lecture.〕 Feynman believed that if the electron microscope could be made powerful enough, then it would become possible to visualize the atomic structure of any and all chemical compounds, including DNA. In 1970, Albert Crewe developed the high-angle annular dark-field imaging (HAADF) imaging technique in a scanning transmission electron microscope. Using this technique, he visualized individual heavy atoms on thin amorphous carbon films. In 2010 Krivanek and colleagues reported several technical improvements to the HAADF method, including a combination of aberration corrected electron optics and low accelerating voltage. The latter is crucial for imaging biological objects, as it allows to reduce damage by the beam and increase the image contrast for light atoms. As a result, single atom substitutions in a boron nitride monolayer could be imaged. Despite the invention of a multitude of chemical and fluorescent sequencing technologies, electron microscopy is still being explored as a means of performing single-molecule DNA sequencing. For example, in 2012 a collaboration between scientists at Harvard University, the University of New Hampshire and ZS Genetics demonstrated the ability to read long sequences of DNA using the technique, however transmission electron microscopy DNA sequencing technology is still far from being commercially available. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Transmission electron microscopy DNA sequencing」の詳細全文を読む スポンサード リンク
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