  Fluorescence polarization microscopy images both the intensity and
orientation of fluorescent dipoles, which plays a vital role in studying the
molecular structure and dynamics of bio-complex. However, it is difficult to
resolve the dipole assemblies on the subcellular structure and their dynamics
in living cells with super-resolution. Here we report polarized structured
illumination microscopy (pSIM), which decouples the entangled spatial and
angular structured illumination through interpreting the dipoles in
spatio-angular hyperspace. We demonstrate its application on a series of
biological filamentous systems such as cytoskeleton networks and lambda-DNA,
and report the dynamics of short actin sliding through myosin-coated surface.
Further, pSIM reveals "side-by-side" organization of the actin ring structure
in the membrane-associated periodic skeleton in hippocampal neurons. It also
images the dipole dynamics of green fluorescent proteins labeled to the
microtubules in live U2OS cells. pSIM can be applied directly to a large
variety of commercial or home-built SIM systems.
