Maternal-effect loci involved in Drosophila oogenesis and embryogenesis: P element-induced mutations on the third chromosome.

A collection of 1609 recessive P-lethal mutations on the third chromosome was tested in germline clones for effects on egg differentiation and embryonic development. In 164 lines, normal differentiation of the egg chamber is prevented and in 841 lines, embryos develop abnormally. This latter group of maternal-effect mutations was subdivided into 23 classes based on the cuticular phenotypes. Our collection comprises new alleles of previously characterized genes (e.g. kayak, punt, string, tramtrack). For some of the genes identified in this screen, a maternal contribution to embryonic development has not been described previously (e.g. extramacrochaete, Trithorax-like, single minded, couch potato, canoe). The genes classified in our study with a dual function during oogenesis and embryogenesis not only substantially extends the existing collection of maternal-effect genes but will also aid further understanding of how patterning of the Drosophila embryo is controlled by the maternal genome.