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Redistribution of Actin during Assembly and Reassembly of the Contractile Ring in Grasshopper Spermatocytes

By G. Bradley Alsop, Wei Chen, Margit Foss, Kuo-Fu Tseng and Dahong Zhang


Cytokinesis in animal cells requires the assembly of an actomyosin contractile ring to cleave the cell. The ring is highly dynamic; it assembles and disassembles during each cell cleavage, resulting in the recurrent redistribution of actin. To investigate this process in grasshopper spermatocytes, we mechanically manipulated the spindle to induce actin redistribution into ectopic contractile rings, around reassembled lateral spindles. To enhance visualization of actin, we folded the spindle at its equator to convert the remnants of the partially assembled ring into a concentrated source of actin. Filaments from the disintegrating ring aligned along reorganizing spindle microtubules, suggesting that their incorporation into the new ring was mediated by microtubules. We tracked incorporation by speckling actin filaments with Qdots and/or labeling them with Alexa 488-phalloidin. The pattern of movement implied that actin was transported along spindle microtubules, before entering the ring. By double-labeling dividing cells, we imaged actin filaments moving along microtubules near the contractile ring. Together, our findings indicate that in one mechanism of actin redistribution, actin filaments are transported along spindle microtubule tracks in a plus-end–directed fashion. After reaching the spindle midzone, the filaments could be transported laterally to the ring. Notably, actin filaments undergo a dramatic trajectory change as they enter the ring, implying the existence of a pulling force. Two other mechanisms of actin redistribution, cortical flow and de novo assembly, are also present in grasshopper, suggesting that actin converges at the nascent contractile ring from diffuse sources within the cytoplasm and cortex, mediated by spindle microtubules

Topics: Research Article
Publisher: Public Library of Science
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Provided by: PubMed Central

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  8. (2007). Cell and molecular biology of the spindle matrix.
  9. (1991). Cell division in Dictyostelium with special emphasis on actomyosin organization in cytokinesis.
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  11. (2003). Conserved microtubule-actin interactions in cell movement and morphogenesis.
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  13. (1996). Cytokinesis in animal cells.
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  22. (2008). Interaction between Anillin and RacGAP50C connects the actomyosin contractile ring with spindle microtubules at the cell division site.
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  24. (1990). Mechanism of the formation of contractile ring in dividing cultured animal cells. I. Recruitment of preexisting actin filaments into the cleavage furrow.
  25. (1990). Mechanism of the formation of contractile ring in dividing cultured animal cells. II. Cortical movement of microinjected actin filaments.
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  27. (2000). Microtubules and mitotic cycle phase modulate spatiotemporal distributions of F-actin and myosin II in Drosophila syncytial blastoderm embryos.
  28. (2003). Microtubules are the only structural constituent of the spindle apparatus required for induction of cell cleavage.
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  30. (2008). Mid1p/anillin and the septation initiation network orchestrate contractile ring assembly for cytokinesis.
  31. (2006). Mitochondria: more than just a powerhouse.
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  36. (2008). Redundant mechanisms recruit actin into the contractile ring in silkworm spermatocytes.
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  38. (2001). Reorganization of actin cytoskeleton at the growing end of the cleavage furrow of Xenopus egg during cytokinesis.
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  40. (2003). Spinning disk confocal microscope system for rapid high-resolution, multimode, fluorescence speckle microscopy and green fluorescent protein imaging in living cells.
  41. (2005). Split decisions: coordinating cytokinesis in yeast.
  42. (2008). Stepping into the ring: the SIN takes on contractile ring assembly.
  43. (1949). The anaphase movement of chromosomes in the spermatocytes of the grasshopper.
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