what is genetic magnification
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Answer:
The sequencing of DNA or proteins is a complex procedure requiring sophisticated analytical techniques. However, a new approach to this almost ubiquitous, yet onerous, task, based on Raman spectroscopy, could make things much simpler and potentially less expensive.
The sequencing of DNA or proteins is a complex procedure requiring sophisticated analytical techniques. However, a new approach to this almost ubiquitous, yet onerous, task, based on Raman spectroscopy, could make things much simpler and potentially less expensive.
Volker Deckert and Elena Bailo of the Institute for Analytical Sciences (ISAS), in Dortmund, Germany, point out that DNA sequencing requires that the technology can separate and visualize specific DNA fragments, moreover, while it relies a research team being able to obtain substantial amounts of the target DNA it does not actually read the base composition of the DNA strand directly.
"A method that utilizes the inherent information of the distinct bases present in DNA or RNA without the need of further labelling is therefore desirable," say Deckert and Bailo. They are now developing just such a method based on tip-enhanced Raman spectroscopy, that functions well with single strands of DNA's extranuclear cousin RNA.
The new approach builds on earlier efforts to recruit scanning tunnelling microscopy (STM) into the array of available tools. STM, however, provides only low contrast and usually needs a detailed statistical analysis to obtain any useful data. Higher contrast is possible with atomic force microscopy (AFM), the team asserts. They have now combined the near-field prowess of AFM, which allows them to investigate and even manipulate a material at the surface level atom-by atom, with Raman spectroscopy to reveal the details along an RNA strand.
The combination of AFM and Raman, exploits the advantages of both techniques will side-stepping the common low contrast of other microscopy techniques and compensating for the poor lateral resolution of Raman by provide atomic level control. "In just a few seconds acquisition time tip-enhanced Raman spectroscopy (TERS) gives high sensitivity at lateral resolution down to a few tens of nucleobases," say the researchers. Similar arrangements have been used previously to study simpler structures such as carbon nanotubes and synthetic polymers, the team points out.
Such a direct approach to sequencing means that the individual letters of the genetic code can be read as if one were simply looking at a strand of RNA with a hypothetical magnifying glass. The "magnifying glass is the AFM, which steers a tiny, silvered glass tip along the length of the RNA strand. A laser beam focused on the tip excites the section of the strand being examined and causes it to vibrate. The resulting Raman spectrum of the scattered light then "reads" the molecular structure of the segment giving a close to base-by-base readout as the AFM tip scans the strand.
Key to their success was the minimal use of buffers (to avoid errant crystals on the scanned surface) and essential control of the RNA to prevent tangling (caused by lack of buffer, ironically enough!). The tip of the AFM must also be guided very precisely so that there is no sample drift, the tip must stay very close to the line of the RNA, in other words.
The researchers concede that direct resolution of individual bases has not yet been achieved. However, it is also not always necessary. The tip only has to be moved over the RNA strand at intervals corresponding to the approximate base to base distance and even if there is overlap in the spectral lines, from several neighbouring bases, the information can by logic be used to derive the sequence of the RNA.
The team hopes to be able to extend TERS to DNA. Such an achievement could revolutionize the decoding of genetic information because it needs just one strand of genetic material, which avoids a whole range of sample preparative steps, such as polymerase chain reaction (PCR). "DNA sequencing could become as simple as reading a barcode at the supermarket," says Deckert. The team is also now investigating the possibility of sequence short protein sequences and peptides, using TERS.
"The actual key to success was not only the sample preparation, but even more the achieved signal-to-noise ratio due to the high enhancement factors of the tips," Deckert told SpectroscopyNOW.
"We think that our approach could also be developed into a system that can compete with PCR," adds Deckert, "The advantages are obvious, in the extreme case only one strand is needed and it can be sequenced very fast. Coming from physical chemistry I have not so much experience with the molecular biology itself," he says, "The molecular biologists I've talked to about the experiments were quite excited about the potential."
Explanation:
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Magnification is the heritable increase of copy number of the X chromosome rDNA array.
The sequencing of DNA or proteins is a complex procedure requiring sophisticated analytical techniques. However, a new approach to this almost ubiquitous, yet onerous, task, based on Raman spectroscopy, could make things much simpler and potentially less expensive.
The sequencing of DNA or proteins is a complex procedure requiring sophisticated analytical techniques. However, a new approach to this almost ubiquitous, yet onerous, task, based on Raman spectroscopy, could make things much simpler and potentially less expensive.
Volker Deckert and Elena Bailo of the Institute for Analytical Sciences (ISAS), in Dortmund, Germany, point out that DNA sequencing requires that the technology can separate and visualize specific DNA fragments, moreover, while it relies a research team being able to obtain substantial amounts of the target DNA it does not actually read the base composition of the DNA strand directly.
"A method that utilizes the inherent information of the distinct bases present in DNA or RNA without the need of further labelling is therefore desirable," say Deckert and Bailo. They are now developing just such a method based on tip-enhanced Raman spectroscopy, that functions well with single strands of DNA's extranuclear cousin RNA.
The new approach builds on earlier efforts to recruit scanning tunnelling microscopy (STM) into the array of available tools. STM, however, provides only low contrast and usually needs a detailed statistical analysis to obtain any useful data. Higher contrast is possible with atomic force microscopy (AFM), the team asserts. They have now combined the near-field prowess of AFM, which allows them to investigate and even manipulate a material at the surface level atom-by atom, with Raman spectroscopy to reveal the details along an RNA strand.
The combination of AFM and Raman, exploits the advantages of both techniques will side-stepping the common low contrast of other microscopy techniques and compensating for the poor lateral resolution of Raman by provide atomic level control. "In just a few seconds acquisition time tip-enhanced Raman spectroscopy (TERS) gives high sensitivity at lateral resolution down to a few tens of nucleobases," say the researchers. Similar arrangements have been used previously to study simpler structures such as carbon nanotubes and synthetic polymers, the team points out.
Such a direct approach to sequencing means that the individual letters of the genetic code can be read as if one were simply looking at a strand of RNA with a hypothetical magnifying glass. The "magnifying glass is the AFM, which steers a tiny, silvered glass tip along the length of the RNA strand. A laser beam focused on the tip excites the section of the strand being examined and causes it to vibrate. The resulting Raman spectrum of the scattered light then "reads" the molecular structure of the segment giving a close to base-by-base readout as the AFM tip scans the strand.