For the first time, we can discern the structure of individual RNA molecules in living plant cells. This new method ‘unlocks a second, hidden layer of the RNA’, researchers from the UK’s John Innes Centre write in Nature.

RNA molecules are important for many biological processes. To understand how RNA molecules influence these processes, knowledge of their structure is necessary. That structure consists of double helix pieces, where two parts of the RNA molecule bind to each other, and single-stranded RNA pieces. Yet researchers have a poor understanding of the structure. To determine the structure of RNA molecules, researchers blindly apply modifications to the pieces of single-stranded RNA. They then read the sequence of the RNA molecules to find out where the modifications are. The researchers can then use the observed modifications to determine the most suitable structure.

With the current method, using the Illumina platform, researchers can read only 100 nucleotides at a time. To determine the structure of longer RNA molecules, researchers merge the information obtained from multiple fragments. Thus, according to Yiliang Ding of the John Innes Centre, principal investigator of the Nature study, they ‘see the structure of RNA molecules as averages, without knowing whether there is large or small variation’.