[
Nature,
1992]
Induction is the process in development in which the fate of one cell mass is determined by another. A simple example occurs during vulval development in the nematode Caenorhabditis elegans: a gonadal cell called the anchor cell induces three neighbouring cells to embark on a programme of cell division and morphogenesis, which culminates, in a few hours, in the formation of a vulva. On page 470 of this issue, Hill and Sternberg report strong evidence that they have identified the anchor-cell signalling molecule, which they find is a member of the EGF (epidermal growth factor) group of growth factors.
[
Nature,
1999]
Advances in human genetics have meant that the genes mutated in human diseases can be identified exclusively by their location in the genome. But how do we work out the cellular functions of the associated protein products? Reports on pages 383 and 386 of this issue begin to address this problem for two proteins - polycystin-1 (PKD1) and polycystin-2 (PKD2) - that are defective in human kidney disease. From their studies of the nematode worm Caenorhabditis elegans, Barr and Sternberg present evidence that homologues of the polycystins act together in a signal-transduction pathway in sensory neurons. Chen et al., by contrast, have used an oocyte-expression system in the from Xenopus laevis to show that a homologue of PKD2 is associated with the activity of a cation channel. These results support the hypothesis that polycystin-related proteins belong to a hitherto unknown class of signal-transduction molecules.