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Ritchie, K. P.

Publications and source records attributed to Ritchie, K. P..

2 recordsLinked to original sources

Development of ultrafast camera-based imaging of single fluorescent molecules and live-cell PALM

The spatial resolution of fluorescence microscopy has recently been greatly improved. However, its temporal resolution has not been improved much, despite its importance for examining living cells. Here, by developing an ultrafast camera system, we achieved the worlds highest time resolutions for single fluorescent-molecule imaging of 33 (100) {micro}s (multiple single molecules simultaneously) with a single-molecule localization precision of 34 (20) nm for Cy3 (best dye found), and for PALM data acquisition of a view-field of 640x640 pixels at 1 kHz with a single-molecule localization precision of 29 nm for mEos3.2. Both are considered the ultimate rates with available probes. This camera system (1) successfully detected fast hop diffusion of membrane molecules in the plasma membrane, detectable previously only by using less preferable 40-nm gold probes and bright-field microscopy, and (2) enabled PALM imaging of the entire live cell, while revealing meso-scale dynamics and structures, caveolae and paxillin islands in the focal adhesion, proving its usefulness for cell biology research. SummaryAn ultrafast camera developed by Fujiwara et al. allows single fluorescent-molecule imaging every 33 s with a localization precision of 34 nm (every 100 s; 20 nm), and enables ultrafast PALM imaging of whole live cells.

cell biology↗

Focal adhesion membrane is dotted with protein islands and partitioned for molecular hop diffusion

Using the ultrafast camera system and new theories for hop diffusion described in the companion paper, we for the first time demonstrated that membrane molecules undergo hop diffusion among the compartments in the bulk basal plasma membrane (PM), with virtually the same compartment sizes (108 nm) as those in the bulk apical PM and the same dwell lifetimes within a compartment (10 and 24 ms for the phospholipid and transferrin receptor, respectively), suggesting that the basic structures and molecular dynamics are very similar in the bulk regions of the apical and basal PMs. Ultrafast PALM and single-molecule imaging revealed that the focal adhesion (FA) is mostly a fluid membrane, partitioned into [~]74-nm compartments where transferrin receptor and {beta}3 integrin undergo hop diffusion, and that the FA membrane is sparsely dotted with 51-nm diameter paxillin islands, where many other FA proteins probably assemble (compartmentalized archipelago model). {beta}3 integrin intermittently associates with the paxillin islands, dynamically linking them to the extracellular matrix. SummaryAn ultrafast camera with single fluorescent-molecule sensitivities developed by Fujiwara et al. reveals that the focal adhesion membrane is dotted with protein islands and partitioned for molecular hop diffusion, and integrin {beta}3 molecules become temporarily immobilized at the islands.

cell biology↗