iochemical and kinetic studies have failed to provide a unified view on how the Arp2/3 complex nucleates actin filaments. Does the complex, which mediates actin filament nucleation and branch formation at the leading edge of motile cells, bind to the side of an older actin filament, or does it become incorporated into that filament? B Structural studies now add a new dimension to the discourse,...

Scientific research is undergoing significant restructuring. New fields are emerging, once-separate fields are merging, and many of us are trying to figure out how to combine tools and thinking from different areas of science. Nearly a year into my second post-doc, I search for the best metaphor to describe my ongoing metamorphosis from chemist to chemical biologist. In graduate school, I learn...

The mechanisms that pattern lateral root primordia are essential for the elaboration of root system architecture , a trait of key importance for future crop breeding. But which are most important: periodic or local cues? In this issue of Journal of Experimental Botany (pages 1411–1420), Kircher and Schopfer manipulate growth direction to demonstrate the importance of both sources of patterning ...