Arrangement of actin filaments and myosin-like filaments in the contractile ring and of actin-like filaments in the mitotic spindle of dividing HeLa cells
Key result
HeLa cell contractile rings display aligned actin and myosin filaments supporting a sliding filament mechanism.
Population
Dividing HeLa cells
Design
Preclinical
Authors
Discussion
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Member takes
Implication
No immediate clinical implications; leaves open generalizability of sliding-filament contractility beyond HeLa cells.
Key Points
- To resolve the structural arrangement of actin and myosin-like filaments within the contractile ring and mitotic spindle during cell division.
- Preserved dividing HeLa cells using a glutaraldehyde-tannic acid-saponin fixative to improve actin filament preservation for thin-section electron microscopy.
- Quantified filament diameters, bundle sizes, packing densities, and spatial relationships within the cleavage furrow and the mitotic spindle.
- The contractile ring contains circumferentially oriented bundles of approximately 25 actin filaments that interdigitate with 13-nm myosin-like thick filaments.
- Contractile ring actin filaments exhibit lower packing density than the ~23 filaments per bundle in filopodia, with some radiating from electron-dense plasma membrane sites.
- The mitotic spindle lacks long actin filaments but contains 400 to 1,000 very short actin-like filaments per cubic micron.
Structured PICO
P
Population
Dividing HeLa cells
E
Exposure
Glutaraldehyde-tannic acid-saponin fixative preparation for thin sectioning
O
Outcome
Arrangement of actin and myosin-like filaments in the contractile ring and mitotic spindlesurrogate
The ultrastructural arrangement of interdigitating actin and myosin-like filaments in the contractile ring of dividing HeLa cells supports a sliding filament mechanism for tension generation during cytokinesis.
Cite This Study
Maupin et al. (1986) studied Dividing HeLa cells. Glutaraldehyde-tannic acid-saponin fixative was evaluated on Arrangement of actin and myosin-like filaments. In dividing HeLa cells, the contractile ring contains parallel actin filament bundles and circumferentially aligned myosin-like thick filaments, consistent with a sliding filament mechanism.