New findings provide evidence that developmentally staged RhoGEFs control assembly of two alternative forms of cleavage furrows: the 'Rappaport' furrows, which govern division of Drosophila syncytial cortical division cycles, and conventional spindle-directed furrows.

The 95F myosin, a class VI unconventional myosin, associates with particles in the cytoplasm of the Drosophila syncytial blastoderm and is required for the ATP- and F-actin-dependent translocation of these particles. The particles undergo a cell cycle-dependent redistribution from domains that surround each nucleus in interphase to transient membrane invaginations that provide a barrier between...

nuclear fallout (nuf) is a maternal effect mutation that specifically disrupts the cortical syncytial divisions during Drosophila embryogenesis. We show that the nuf gene encodes a highly phosphorylated novel protein of 502 amino acids with C-terminal regions predicted to form coiled-coils. During prophase of the late syncytial divisions, Nuf concentrates at the centrosomes and is generally cyt...

Calcium signaling is known to be associated with cytokinesis; however, the detailed spatio-temporal pattern of calcium dynamics has remained unclear. We have studied changes of intracellular free calcium in cleavage-stage Xenopus embryos using fluorescent calcium indicator dyes, mainly Calcium Green-1. Cleavage formation was followed by calcium transients that localized to cleavage furrows and ...

Early Drosophila embryogenesis is characterized by shifting from astral microtubule-based to central spindle-based positioning of cleavage furrows. Before cellularization, astral microtubules determine metaphase furrow position by producing Rappaport-like furrows, which encompass rather than bisect the spindle. Their positioning is explained by our finding that the conserved central spindle com...

S plitting mitotic cells in two is not the one-way signaling road it once seemed, based on evidence from Hu et al. The group identifi es a positive feedback loop that creates a furrow at cytokinesis. The fi ndings also throw a wrench in the well-accepted dogma of microtubule dynamic instability. Hu and colleagues devised a monopolar HeLa system to determine how the cytokinetic furrow is created...

The transport of runoff with high copper concentrations and sediment loads into adjacent surface waters can have adverse effects on nontarget organisms as a result of increased turbidity and degraded water quality. Runoff from vegetable production utilizing polyethylene mulch can contain up to 35% of applied copper, a widely used fungicide/bactericide that has adverse effects on aquatic organis...