Lipid microscopy

A chance meeting with a cosmochemist has led Steven Boxer to a new way to precisely image lipid locations. With Mary Kraft (Stanford University, Stanford, CA) and colleagues, he hopes to test ideas generated by the raft hypothesis. “A lot of this is cartoons,” says Boxer. “We want to translate these cartoons of membrane molecules into reality.”

The technique fills in a gap between FRET (operating over a maximum of a few nanometers) and optical microscopy (several hundreds of nanometers or more). Now, the NanoSIMS (secondary ion mass spectrometry) machine identifies lipid distributions with a lateral resolution of ∼100 nm.

The NanoSIMS sweeps a focused beam of cesium ions over the sample in around 10 minutes. The high-energy beam almost completely fragments proteins and lipids. Thus, molecules can be easily identified only...