Stage-specific requirement for myosin II during Dictyostelium development.
Dictyostelium cells that lack a functional myosin II heavy chain are motile and are capable of aggregation, but fail to undergo further multicellular development. We have used a Dictyostelium mutant expressing a cold-sensitive myosin heavy chain to examine the requirement for myosin throughout the course of development. The loss of myosin function upon cooling is rapid and reversible. Temperature-shift experiments reveal that myosin is essential during two different stages of development. During aggregation, myosin function appears to be necessary for cells to sort correctly in a way that allows further development to occur. During the final stage of development, it is required for the formation of a complete stalk and the raising of the spore head. Development between those stages, however, proceeds normally in the absence of myosin function. Aggregates at non-permissive temperature undergo an aberrant form of development resulting in a ball of cells. Calcofluor staining and reporter gene fusions reveal that these structures contain defective spores and a miniature stalk.
Department of Biochemistry, Stanford University School of Medicine, CA 94305-5307.
M L
ML
Springer
B
B
Patterson
J A
JA
Spudich
D000818:Animals; D002449:Cell Aggregation / Q000502:physiology; D003080:Cold Temperature; D004023:Dictyostelium / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D017125:Genes, Protozoan; D009154:Mutation; D009218:Myosins / Q000502:physiology*; D010641:Phenotype
D009218:Myosins