The genetic control of development is well understood in Drosophila, but how have genetic programs changed during the course of evolution? Some regulatory genes are conserved over vast evolutionary distances, such as the the Hox genes that control cell fates along the antero-posterior axis. Others have changed rapidly. The full spectrum can best be understood by studying organisms ranging from close relatives of the model systems, through a series of more distantly related species. The focus here is on embryonic patteming in the wasp Nasonia vitripennis. Nasonia is more closely related to Drosophila than are other well-studied insects such as beetles and grasshoppers. The Pultz lab has isolated zygotic mutations that identify Nasonia embryonic patterning genes. The next step is developing molecular tools to illuminate mechanisms of Nasonia early development and to study two interesting Nasonia patterning genes, headless and head only. These genes have phenotypic similarities to patterning genes in Drosophila, but affect larger regions of the embryo than Drosophila zygotic genes, suggesting that zygotic gene functions may play a larger role in the wasp than in the fly. The experimental approaches will be threefold. (1) The relationship between headless and head only will be studied through double mutant analysis. (2) Nasonia counterparts of Drosophila genes will be studied by linkage analysis and DNA sequencing, asking whether headless is Nasonia hunchback and whether head only may be Nasonia Kruppel, caudal, nanos or pumilio. (3) Expression of Nasonia hunchback and caudal RNA and protein products will be examined in wild type embryos, asking whether these gene products are provided maternally as well as zygotically. Nasonia hunchback and caudal expression will also be analyzed in head only and headless mutant embryos. This work will include construction of embryonic cDNA libraries, isolation of cDNA clones, in situ hybridizations and construction of fusion proteins for raising antibodies. Protein gradients will be examined by three-dimensional reconstructions of fluorescently-stained embryos. Together, these experiments will address hypotheses about headless and head only identities and functions, and will explore whether Nasonia and Drosophila differ in their dependence on maternally loaded developmental regulatory gene products.
