The first morphogenetic process of Drosophila development is the formation of the primary epithelium by cellularisation, during which invagination of the plasma membrane packages the nuclei into around 6000 distinct cells. Using microarrays, RNAi and time-lapse phenotyping, Lecuit and colleagues have identified several novel genes that profoundly affect cellular architecture during cellularisation. Their paper on focuses on one of these genes - charleston (char). They show that epithelial nuclei lacking Char (owing to mutation or RNAi) fail to elongate during cellularisation and instead remain spherical, which distorts cell shape and the normal columnar morphology of the epithelium. Unexpectedly, the binding of microtubules to the nuclear envelope is unaffected in charRNAi embryos. Instead, Char's localisation to the inner nuclear membrane indicates that it directly controls the structural organisation of the nuclear envelope. The authors suggest that Char is a component of a nucleoskeleton needed by the nuclear membrane to respond to microtubules; whether this is true will become clear as its molecular partners are identified.
