Abstract

Fluorescent dipoles reflect the spatial orientation of the fluorophores, which indicates structural information of the targeted proteins. Imaging of fluorescent dipoles has been widely applied in structural research of cell membranes, biological filaments, and macromolecules. However, it suffers from the Abbe's diffraction limit, which deteriorates the imaging accuracy of both position and orientation of the fluorescent dipoles. Recently we developed several super-resolution tools to image the molecular orientation of fluorophores, including super-resolution dipole orientation mapping (SDOM) [1] and polarized structured illumination microscopy (pSIM) [2]. Our techniques model the fluorophores in the spatio-angular domain, describing both their position and orientation, which adds not only further super-resolution but also valuable biological insights. For the first time, our technique revealed the “side-by­side” organization the actin filaments in the “actin ring” structure of Membrane- associated Periodic Structure (MPS) in hippocampal neurons. Together with spectral detection, we also uncover the lipid heterogeneities of ten subcellular compartments [3], during different developmental stages of organelles, and even within the same organelle. The versatile applications of our technique suggest the broad application of super-resolution fluorescence polarization in future biological research.

© 2021 The Author(s)