Novel cytokinetic ring components drive negative feedback in cortical contractility

Formin’ the cytokinetic ring

A ll animal and fungal cells assemble a contractile actomyosin ring to divide themselves in two at the end of mitosis. The rings are constructed from actin fi laments formed de novo at the division site and from fi laments that are assembled elsewhere in the cell and transported to the cleavage zone. Both types of fi lament are generated by actinnucleating formin proteins, but whether one sourc...

Negative plant soil feedback explaining ring formation in clonal plants.

Ring shaped patches of clonal plants have been reported in different environments, but the mechanisms underlying such pattern formation are still poorly explained. Water depletion in the inner tussocks zone has been proposed as a possible cause, although ring patterns have been also observed in ecosystems without limiting water conditions. In this work, a spatially explicit model is presented i...

Mechanism of cytokinetic contractile ring constriction in fission yeast.

Cytokinesis involves constriction of a contractile actomyosin ring. The mechanisms generating ring tension and setting the constriction rate remain unknown because the organization of the ring is poorly characterized, its tension was rarely measured, and constriction is coupled to other processes. To isolate ring mechanisms, we studied fission yeast protoplasts, in which constriction occurs wit...

Positive Feedback Between Contractile Ring Myosin and Ring-Directed Cortical Flow Drives Cytokinesis

Still and rotating myosin clusters determine cytokinetic ring constriction

The cytokinetic ring is essential for separating daughter cells during division. It consists of actin filaments and myosin motors that are generally assumed to organize as sarcomeres similar to skeletal muscles. However, direct evidence is lacking. Here we show that the internal organization and dynamics of rings are different from sarcomeres and distinct in different cell types. Using micro-ca...