Highly read on pubs.acs.org in December
Nearly 60 years after the structure of DNA was first discovered, scientists using transmission electron microscopy have captured direct images of it.
Enzo di Fabrizio at the Italian Institute of Technology in Genoa and his colleagues spread droplets of fluid containing DNA from a bacterium-infecting virus onto silicon wafers that were etched with micrometre-scale pillars and holes. As the droplets dried overnight, the DNA stretched taut across the tops of the pillars, passing over some of the holes. The researchers then imaged the DNA (pictured; scale bar, 20 nanometres) by beaming electrons through the holes.
The team observed a structure with helices that repeated roughly every 2.7 nanometres (inset, red arrows), consistent with A-DNA — a non-physiological DNA conformation known to occur in dehydrated samples.