We count nucleic acids with the accuracy of a molecule

A new method of DNA counting is proposedAlexander Sotov, Rossiyskaya Gazeta 

Biologists from the University of Helsinki (Finland) and the Karolinska Institute (Sweden) have proposed a new empirical method for estimating the number of DNA and RNA molecules that can increase the accuracy of modern technologies for reading and copying carriers of genetic information (Karolinska Institutet, A better way to count molecules discovered – VM).

In an article published in the journal Nature Methods (Kivioja et al., Counting absolute numbers of molecules using unique molecular identifiers), a method for counting the absolute number of molecules in a sample is proposed, which does not require either identification of each individual molecule or accounting for copies made from them. This is achieved due to the fact that the analyzed molecule is first made unique. A special label is used for this. It can serve as a randomly compiled fragment of DNA, which scientists attach to fragments of the analyzed chain, or an arbitrary section in each segment of the molecule after splitting it into short chains of nucleotides.

Counting the number of biological molecules is the most important task in assessing the cellular response, which is necessary for many clinical measurements. There are a large number of analytical methods for estimating the relative number of DNA by sampling analysis, however, in clinical practice, the only available method for estimating the absolute number of molecules remains the digital polymerase chain reaction (digital PCR) method, which is limited by the fact that one specific molecule is examined for each analysis. The new method is designed to remove these limitations, since "it can be used to estimate the number of molecules without observing each of them separately," the authors of the article note.

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22.11.2011