Photostable dye improves superresolution imaging of mitochondria

Photostable dye improves superresolution imaging of mitochondria


Stimulated emission depletion (STED) microscopy is a superresolution imaging method that can enable live cell imaging at high spatial and temporal resolution. However, the strong lasers used in STED microscopy rapidly bleach fluorescent dyes used to visualize mitochondria, which are the powerhouses of eukaryotic cells.

Researchers fashioned a fluorescent probe named MitoPB Yellow, whose high photostability, long fluorescence lifetime, and specificity for the mitochondrial inner membrane render it a superior tool for live STED imaging of the organelle, compared with conventional dyes such as MitoTracker Green FM, MitoTracker Deep Red FM, and Rhodamine 123.

MitoPB Yellow enabled visualization of ultrastructural features of mitochondrial cristae—folds of the inner membrane that serve to maximize surface area for energy generation—at 60-nm resolution while using a 660-nm depletion laser.

The dye revealed fine details of the mitochondrial inner membrane in live mammalian cells previously visible only through electron microscopy and allowed the authors to derive accurate counts of cristae from the fluorescence intensity.

Additionally, MitoPB Yellow helped observe the dynamic remodeling of cristae in cells exposed to starvation and apoptotic stress as well as the merging of cristae within individual mitochondria and fusion between mitochondria.

According to the authors, the findings demonstrate the advantages of MitoPB Yellow for STED imaging of mitochondrial membrane structure and dynamics in living cells.