Cell structure and dynamics.

Rebecca Heald is in the Department of Molecular and Cell Biology at the University of California, Berkeley. Her lab uses cytoplasmic extracts from Xenopus eggs to reconstitute and study spindle assembly and chromosome segregation in vitro, as well as mechanisms of spindle and organelle size control. The cytoskeleton is at the heart of cell structure and dynamics, both in eukaryotes and in prokaryotes. Recent studies highlight the central role of the cytoskeleton in positioning organelles and determining their morphology and function. A major theme in this issue of Current Opinion in Cell Biology is the link between cytoskeletal elements and other cellular components, from the plasma membrane to the Golgi and nucleus. A highly specialized attachment between spindle microtubules and chromosomes occurs at the kinetochore, and several reviews in this issue deal with how mitotic chromosomes form, and the causes and consequences of their missegregation. This set of reviews reflects the wide range of approaches used in cell biology that continue to yield a more detailed understanding of many cellular phenomena that underlie cell structure as well as dynamic events including cell migration and division, and muscle contraction.