Related Experiment Videos
Organization and spatial arrangement of fluorescein-labeled native actin microinjected into normal locomoting and
Abstract:
Fully polymerization-competent fluorescein-labeled actin from skeletal muscle was microinjected into both normal moving and experimentally treated Amoeba proteus. Its intracellular distribution was followed by integral image intensification of the fluorescence on a television screen and compared with controls injected with rhodamine-labeled serum albumin. The labeled actin was incorporated into the endogenous actin pool and exhibited a characteristic redistribution depending on the cellular morphology. Increased amounts of labeled actin could be detected within a thin layer separating the hyalo- and granuloplasm or running immediately beneath the plasma membrane when hyaloplasmic regions were absent. The topography of the fluorescent layer demonstrated in living cells is in agreement with the cortical microfilament layer described ultrastructurally recently in corresponding cells. The combined results emphasize the important role of the cortical filament layer in both morphogenetic processes (e.g., hyalo-granuloplasm separation or changes in cell shape) and motive force generation for cytoplasmic streaming and amoeboid movement.
Insights
Fluorescein-labeled actin in Amoeba proteus revealed a dynamic cortical layer crucial for cell shape, movement, and internal organization. This study highlights actin's role in fundamental cellular processes.
Area of Science:
- Cell Biology
- Biophysics
- Cytoskeleton Dynamics
Background:
- Actin dynamics are fundamental to cell motility and morphology.
- The cortical actin network's precise role in Amoeba proteus requires further elucidation.
- Understanding actin distribution is key to deciphering cellular mechanics.
Purpose of the Study:
- To investigate the intracellular distribution and dynamics of polymerization-competent actin in Amoeba proteus.
- To correlate actin localization with cellular morphology and movement.
- To validate the existence and function of a cortical microfilament layer.
Main Methods:
- Microinjection of fluorescein-labeled skeletal muscle actin into Amoeba proteus.
- Real-time fluorescence imaging using integral image intensification.
- Comparison with rhodamine-labeled serum albumin controls.
- Correlation of fluorescence patterns with cell morphology and behavior.
Main Results:
- Labeled actin integrated into the endogenous actin pool.
- Actin exhibited redistribution patterns dependent on cellular morphology.
- Increased labeled actin localized to a thin layer between hyalo- and granuloplasm and beneath the plasma membrane.
- Observed fluorescent layer topography aligns with ultrastructurally described cortical microfilaments.
Conclusions:
- The cortical filament layer plays a significant role in morphogenetic processes like hyalo-granuloplasm separation and shape changes.
- This layer is vital for generating motive force in cytoplasmic streaming and amoeboid movement.
- The study provides in vivo evidence for the functional importance of the cortical actin network in Amoeba proteus.