Live correlative light-electron microscopy to observe molecular dynamics in high resolution

Fluorescence microscopy (FM) is a powerful tool for observing specific molecular components in living cells, but its spatial resolution is relatively low. In contrast, electron microscopy (EM) provides high-resolution information about cellular structures, but it cannot provide temporal information in living cells. To achieve molecular selectivity in imaging at high resolution, a method combining EM imaging with live-cell fluorescence imaging, known as live correlative light-EM (CLEM), has been developed. In this method, living cells are first observed by FM, fixed in situ during the live observation and then subjected to EM observation. Various fluorescence techniques and tools can be applied for FM, resulting in the generation of various modified methods that are useful for understanding cellular structure in high resolution. Here, we review the methods of CLEM and live-cell imaging associated with CLEM (live CLEM). Such methods can greatly advance the understanding of the function of cellular structures on a molecular level, and thus are useful for medical fields as well as for basic biology.