Mutations that alter the morphology of the malpighian tubules in Drosophila.

During Drosophila embryogenesis the malpighian tubules evaginate from the hindgut anlage and in a series of morphogenetic events form two pairs of long narrow tubes, each pair emptying into the hindgut through a single ureter. Some of the genes that are involved in specifying the cell type of the tubules have been described. We surveyed mutations of previously described genes and identified ten among those surveyed that are required for morphogenesis of the malpighian tubules. Of those ten, four block tubule development at early stages, four block later stages of development, and two, rib and raw, which we have described previously, alter the shape of the tubules without arresting specific morphogenetic events. Three of the genes, sna, twi, and trh, are known to encode transcription factors and are therefore likely to be part of the network of genes that dictate the malpighian tubule pattern of gene expression.