Modulating RhoA effectors induces transitions to oscillatory and more wavelike RhoA dynamics in zygotes.

Pulsatile RhoA dynamics underlie a wide range of cell and tissue behaviors. The circuits that produce these dynamics in different cells share common architectures based on fast positive and delayed negative feedback through F-actin, but they can produce very different spatiotemporal patterns of RhoA activity. However, the underlying causes of this variation remain poorly understood.

Single-molecule analysis of cell surface dynamics in Caenorhabditis elegans embryos.

We describe a general, versatile and minimally invasive method to image single molecules near the cell surface that can be applied to any GFP-tagged protein in Caenorhabditis elegans embryos. We exploited tunable expression via RNAi and a dynamically exchanging monomer pool to achieve fast, continuous single-molecule imaging at optimal densities with signal-to-noise ratios adequate for robust single-particle tracking (SPT). We introduce a method called smPReSS, single-molecule photobleaching relaxation to steady state, that infers exchange rates from quantitative analysis of single-molecule photobleaching kinetics without using SPT.