Niepielko, Matthew Gene. Systematic analysis of bone morphogenetic protein signal diversification across Drosophila species during oogenesis. Retrieved from https://doi.org/doi:10.7282/T3C53KXH
DescriptionEggshells of Drosophila species provide great examples of morphological variation. The eggshell is a three-dimensional structure that protects the developing embryo from the surrounding environment and allows continuous gas exchange via tube-like structures called dorsal appendages (DAs). The number, size, shape, and positions of DAs vary among Drosophila species. During animal development, a handful of signaling pathways control tissue differentiation and morphogenesis. In general, mechanisms governing signal diversification that guide morphological variation remain largely unexplored. One conserved signaling pathway involved in guiding tissue development during Drosophila oogenesis is the Bone Morphogenetic Protein (BMP) signaling pathway. Representing a variety of eggshell morphologies, 16 Drosophila species were screened for diversity in BMP signaling during oogenesis. During early oogenesis, BMP signaling in all species was maintained in similar patterns displaying only anterior-posterior polarity. However, BMP signaling during late oogenesis acquired patterns with distinct dorsal-ventral polarities in all species. Further analyses of late patterns revealed five unique patterning groups. Using genetic tools, we demonstrated that the BMP type I receptor thickveins (tkv) accounted for BMP signaling diversification. Based on signaling diversity, computational modeling was employed to predict patterns of tkv that were further tested experimentally. For most species, it was concluded that spatial changes to tkv guided diversification of late BMP signaling. In species belonging to the D. virilis-repleta radiation, tkv partially accounted for BMP signaling diversity and, for that radiation, the model proposes the involvement of another receptor in guiding BMP signaling. These results establish tkv as a major component in regulating BMP signaling diversification across 45 million years of evolution.