New technologies in imaging

Visualization of cellular and molecular processes is an indispensable tool for cell biologists, and innovations in microscopy methods unfailingly lead to new biological discoveries. Today, light micros-copy (LM) provides ever-higher spatial and temporal resolution and visualization of biological process over enormous ranges. Electron microscopy (EM) is moving into the atomic resolution regime and allowing cellular analyses that are more physiological and sophisticated in scope. Importantly, much is being gained by combining multiple approaches, (e.g., LM and EM) to take advantage of their complementary strengths. The advent of high-throughput micros-copies has led to a common need for sophisticated computational methods to quantitatively analyze huge amounts of data and translate images into new biological insights. In vivo imaging requires carefully balancing conflicting parameters to achieve high imaging speed, low photobleaching and pho-totoxicity, good three-dimensional resolution, high signal-to-noise ratio, and excellent physical coverage. Light-sheet microscopy provides outstanding performance in all of these categories and has become a key imaging method for the life sciences. Philipp Keller (Janelia Farm) showed how entire Drosophila embryos can be im-aged throughout embryogenesis at a spatiotemporal resolution that enables comprehensive cell tracking. The use of automated approaches for computational image analysis enables systematical reconstruction of cell lineage information from such recordings in real time. Progress in the light-sheet microscopy field is faster than ever, and further improvements in temporal and spatial resolution are expected in the near future. These capabilities will directly synergize with the rapid progress in related fields, such as the development of advanced fluorescent reporter strategies, powerful approaches to high-throughput data analysis, and computational tools for biophys-ical modeling, opening up exciting new opportunities for micros-copy-based research in the life sciences. Superresolution imaging is enabling the visualization of intracel-lular relationships unobtainable using traditional fluorescent micros-copy. However, different superresolution techniques are based on distinct physical principles to break conventional light microscopy limitations, and these principles determine the apparent size of the biological structure being imaged. The 25-nm-microtubule diameter appears to be between 30 and 120 nm, depending on the technique used. These specific principles also define the acquisition speed of each method, resulting in a family of techniques, with each technique optimized for both size (e.g., organelles vs. transmem-brane receptors) and dynamics (e.g., slow transport vs. diffusion). Recent advances that combine multiple approaches to address a biological question show great promise for overcoming these limitations. Catherine Galbraith (National Institutes of Health) showed how live-cell superresolution imaging of …