Cryo-electron tomography provides first view of a cell’s nucleus in its natural, undisturbed environment

Researchers have gotten a glimpse of the membrane surrounding an intact cell’s nucleus using cryo-electron tomography, revealing the technique’s unique ability to peer past a cell’s cluttered cytoplasm and focus in on its buried organelles. Other structural biology techniques, such as cryo-electron microscopy, cannot resolve cellular elements beyond an intact cell’s surface, explains Julia Mahamid of the Max Planck Institute for Biochemistry, a member of the research team (Science 2016, DOI: 10.1126/science.aad8857). By capitalizing on recent innovations in cryo-transmission electron microscopy, detector sensitivity, and phase contrast enhancement, the team could visualize, for the first time, features on the nuclear membrane surface in their natural context, such as the nuclear pore complex—a revolving door for RNA, proteins, carbohydrates, and more—and previously unseen nuclear laminar filaments, which are just 2–4 nm in diameter. These protein filaments (shown in this computer-generated image) provide stiff structural support to the nucleus, Mahamid says, making it the least pliable organelle in the cell.