A technique can snatch RNA out of a single cell in live, intact tissue, revealing the genes being expressed by that cell.

Other methods of single-cell RNA retrieval tend to disrupt the surrounding tissue before the RNA is captured. James Eberwine of the University of Pennsylvania in Philadelphia and his colleagues created a molecule called a TIVA tag that penetrates cells.

When hit with a beam of light, the tag binds to RNA that is being made from its DNA template. By adding the tag to human and mouse brain tissue and shining a laser on individual cells, the researchers could activate the tag, retrieve the RNA and sequence it.

The approach could reveal how a cell's natural microenvironment affects its activity.

Nature Meth. http://dx.doi.org/10.1038/nmeth.2804 (2014)