Genetic Material under a Magnifying Glass

Jan 28, 2008

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.”

Citation: Volker Deckert, Tip-Enhanced Raman Spectroscopy of Single RNA Strands: Towards a Novel Direct-Sequencing Method, Angewandte Chemie International Edition, doi: 10.1002/anie.200704054

Source: Angewandte Chemie

Explore further: Scientists find clues to cancer drug failure

add to favorites email to friend print save as pdf

Related Stories

Epigenetic 'switch' regulates RNA-protein interactions

4 hours ago

Chemical changes - also known as epigenetic modifications - to messenger RNA (mRNA) are thought to play an important role in gene expression, and have recently been found to affect biological processes such as circadian clock ...

DNA 'cage' could improve nanopore technology

Feb 10, 2015

Despite having a diameter tens of thousands of times smaller than a human hair, nanopores could be the next big thing in DNA sequencing. By zipping DNA molecules through these tiny holes, scientists hope ...

Genetics lab unravels mystery killing at sea

Feb 05, 2015

Observers on a NOAA Fisheries marine mammal survey some 200 miles off the coast of Central California had spotted the telltale signs of a killer whale attack through high-powered binoculars a few miles away. ...

Recommended for you

Scientists find clues to cancer drug failure

8 hours ago

Cancer patients fear the possibility that one day their cells might start rendering many different chemotherapy regimens ineffective. This phenomenon, called multidrug resistance, leads to tumors that defy ...

Smart crystallization

13 hours ago

A novel nucleating agent that builds on the concept of molecularly imprinted polymers (MIPs) could allow crystallographers access to proteins and other biological macromolecules that are usually reluctant ...

Supersonic electrons could produce future solar fuel

13 hours ago

Researchers from institutions including Lund University have taken a step closer to producing solar fuel using artificial photosynthesis. In a new study, they have successfully tracked the electrons' rapid transit through ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.