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David Knecht's Dictyostelium Movies

The role of myosin in multicellular motility.
In order to determine why mutants that lack myosin are incapable of undergoing morphogenesis, we have begun to analyze the motile behavior of cells during multicellular development.

When wild-type cells are labeled with chloromethyl fluorescein diacetate, mixed with an excess of unlabeled cells, and allowed to develop, the labeled cells can be visualized within the multicellular mass by laser scanning confocal microscopy. Wild-type cells show surprisingly dynamic behavior, changing relative positions and moving laterally within aggregation streams. (1.5 Mb)

Cells lacking myosin accumulate at the edges of aggregation streams and become distorted by their adhesive interaction with wild-type cells. Mutant cells end up at the outside of the aggregate, the back of the slug and the base of the fruiting body. (2.2 Mb)

The results support the notion that the actin cortex of mutant cells is especially flaccid leading to their inability to resist forces generated during morphogenesis and to generate force to penetrate between adhered cells.

Shelden, E. and Knecht, D.A. (1995) Mutants lacking myosin II cannot resist forces generated during multicellular morphogenesis. J. Cell Sci, 108: 1105-1115.
Knecht, D.A. and Shelden, E. (1995) Three Dimensional Localization of Wild-Type and Myosin II Mutant Cells during Morphogenesis of Dictyostelium. Developmental Biology, 170: 434-444.

Comments or Questions to David Knecht: (
University of Connecticut, Storrs

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