Gene duplication and divergence has emerged as an important aspect of developmental evolution. The genomes of Caenorhabditis nematodes encode an ancient family of PUF RNA-binding proteins. Most have been implicated in germline development, and are often redundant with paralogs of the same sub-family. An exception is Cbr-puf-2 (one of three Caenorhabditis briggsae PUF-2 sub-family paralogs), whi...

Animal development relies on signals that trigger or inhibit growth and differentiation in precise places and at precise times, so that a new organ, say, forms ‘‘right here’’ instead of ‘‘over there.’’ The outline of that signaling process has been known for some time, with diffusible molecules released from various sites establishing a set of gradients that form an ever-more specific map of th...

The LIN-3-LET-23-mediated inductive signaling pathway plays a major role during vulval development in C. elegans. Studies on the components of this pathway have revealed positive as well as negative regulators that function to modulate the strength and specificity of the signal transduction cascade. We have carried out genetic screens to identify new regulators of this pathway by screening for ...

The Hox gene lin-39 plays a crucial role in the establishment of the nematode vulva equivalence group. Mutations in lin-39 in Caenorhabditis elegans and Pristionchus pacificus result in a vulvaless phenotype because presumptive vulva precursor cells adopt non-vulval fates. Interestingly, the non-vulval fate of anterior and posterior epidermal cells differs between Caenorhabditis and Pristionchu...

Studies of Schizosaccharomyces pombe and mammalian cells identified a series of histone modifications that result in transcriptional repression. Lysine 9 of histone H3 (H3K9) is deacetylated by the NuRD complex, methylated by a histone methyltransferase (HMT) and then bound by a chromodomain-containing protein, such as heterochromatin protein 1 (HP1), leading to transcriptional repression. A Ca...

The Caenorhabditis elegans locus lin-15 negatively regulates an intercellular signaling process that induces formation of the hermaphrodite vulva. The lin-15 locus controls two separate genetic activities. Mutants that lack both activities have multiple, ectopic pseudo-vulvae resulting from the overproduction of vulval cells, whereas mutants defective in only one lin-15 activity appear wild-typ...