Key Points
- Determine the structural polarity and spatial arrangement of actin microfilaments within stress fibers and cleavage furrows during interphase and cell division.
- Permeabilized rat kangaroo (PtK2) cells using ethanol at -20 °C and labeled microfilaments with heavy meromyosin (HMM) to determine filament polarity.
- Fixed specimens with tannic acid and glutaraldehyde for transmission electron microscopic visualization of microfilament banding patterns.
- Actin filaments demonstrated uniform polarity pointing away from cell junctions and attachment plaques, but exhibited mixed parallel and antiparallel orientations within stress fibers and cleavage furrows.
- Cleavage furrow fibers showed alternating dark and light bands measuring approximately 0.16 µm each, identical to stress fibers, which disappeared once the mid-body formed.
- Decorated actin filaments spanned across as many as four band lengths, accompanied by undecorated 10 nm filaments situated within the light bands.
Structured PICO
PPopulationInterphase and cleaving rat kangaroo (PtK2) cells
IInterventionHeavy meromyosin (HMM) decoration followed by tannic acid-glutaraldehyde fixation for electron microscopy
OOutcomePolarity and banding of actin filamentssurrogate
The study proposes a model explaining the arrangement of actin filaments in stress fibers and cleavage furrows based on observed striations and polarity.