Cytoplasmic Filaments of Amoeba Proteus
Authors
Discussion
Loading...
Member takes
Overview
In vitro analysis reveals ATP-stimulated filament assembly and viscosity changes in Amoeba proteus extracts, indicating that two distinct filament types drive ameboid movement.
Key Points
- To investigate the structural and mechanical roles of cytoplasmic filaments in viscosity changes and movement within cell-free extracts of Amoeba proteus.
- Isolated motile cytoplasmic extracts and isolated groundplasm fractions from Amoeba proteus at 0°C using the Thompson and Wolpert extraction method.
- Tracked structural and physical transformations upon warming to 22°C in the presence of ATP using light microscopy, polarization microscopy, electron microscopy, and viscosity measurements.
- Warming extracts to 22°C with ATP triggered a biphasic response: phase one produced an increase in apparent viscosity accompanied by newly formed 50–70 Å thin filaments, followed by phase two where 70 Å filaments aggregated into birefringent microscopic fibrils.
- Pure groundplasm devoid of 160 Å filaments and membranous organelles formed 50–70 Å filaments and birefringent fibrils upon ATP stimulation but exhibited little to no motility, showing that both 50–70 Å and 160 Å filaments are necessary for cytoplasmic streaming.
Cite This Study
Pollard et al. (1970) studied this question.