The genetic alphabet contains four letters. Although our cells can readily decipher our genetic molecules, it isn’t so easy for us to read a DNA sequence in the laboratory. Scientists require complex, highly sophisticated analytical techniques to crack individual DNA codes.
Volker Deckert and his team at the Institute for Analytical Sciences (ISAS) in Dortmund have recently developed a method that could provide a way to directly sequence DNA. Their process is based on a combination of Raman spectroscopy and atomic force microscopy. As reported in the journal Angewandte Chemie, Deckert and Elena Bailo have successfully analyzed DNA’s closest relative, RNA.
Direct sequencing means that the letters of the genetic code are read directly, as if with a magnifying glass. A DNA or RNA strand has a diameter of only two nanometers, so the magnification must be correspondingly powerful. Deckert’s team uses an atomic force microscope to achieve this degree of magnification. Steered by the microscope, a tiny, silvered glass tip moves over the RNA strand. A laser beam focused on the tip excites the section of the strand being examined and starts it vibrating. The spectrum of the scattered light (Raman spectrum) gives very precise information about the molecular structure of the segment. Each genetic “letter”, that is, each of the nucleic acids, vibrates differently and thus has a characteristic spectral “fingerprint”.
The direct resolution of individual bases has not been attainable, but is also not necessary. The tip only has to be moved over the RNA strand at intervals corresponding to about the base-to-base distance. Even if the measured data then consist of overlapped spectra from several neighboring bases, the information can be used to derive the sequence of the RNA.
If this method, known as tip-enhanced Raman spectroscopy (TERS), can be extended to DNA, it could revolutionize the decoding of genetic information. Previous methods for sequencing DNA are highly complex, work indirectly, and require a large sample of genetic material. In contrast, the TERS technique developed by Deckert directly “reads” the code without chemical agents or detours. It also requires only a single strand of DNA. “DNA sequencing could become very simple,” says Deckert, “like reading a barcode at the supermarket.”
Author: Volker Deckert, ISAS Dortmund (Germany), http://www.isas.de/index.php?id=491
Title: Tip-Enhanced Raman Spectroscopy of Single RNA Strands: Towards a Novel Direct-Sequencing Method
Angewandte Chemie International Edition, doi: 10.1002/anie.200704054
World’s Largest Study on Allergic Rhinitis Reveals new Risk Genes
17.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Plant mothers talk to their embryos via the hormone auxin
17.07.2018 | Institute of Science and Technology Austria
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering