Researchers in Japan have discovered a way to detect cytosine methylation in DNA that could be used in epigenotyping. 

Akimitsu Okamoto and colleagues at Kyoto University have distinguished cytosine from 5-methylcytosine using their large differences in osmium oxidation. The researchers found that 5-methylcytosine was oxidised efficiently by a reaction mixture containing an osmium compound, while cytosine was oxidised only weakly.

5-Methylcytosine appears in genomic DNA and plays a key role in epigenetic events, which affect the control of gene expression and cell differentiation, said Okamoto.

'Detecting the existence of only one methyl group in a long strand of DNA is like finding a needle in a haystack,' said Okamoto. 'Analysis of the cytosine methylation status of a gene is very important for understanding the expression mechanism of genetic information. Exposition of many secrets on the origin of cancer and cell differentiation will be possible.' 

Okamoto said this method can be used for the epigenotyping of a small amount of gene sample. The next step is to develop 'quantitative and highly sensitive detection of the cytosine methylation status at a specific site in a long sequence. Application to high throughput epigenotyping systems is also challenging.' 

Nicola Nugent