Characterization of eggshell diversity among Drosophilidae species: signaling, patterning and morphogenesis

Morphological diversity is exhibited throughout nature yet the differences in the developmental mechanisms which contribute to the variety of traits remain mostly unknown. Drosophila melanogaster oogenesis is a model system used for understanding tissue patterning and development. During oogenesis, the follicle cells, a monolayer of epithelial cells engulfing the developing oocyte, are instructed by several cell to cell signaling pathways, including the epidermal growth factor receptor (EGFR) and bone morphogenetic protein (BMP), to transform from a 2 dimensional (2D) cell-layer into the eggshell’s 3D structures. The eggshell itself possesses features that are common or unique to each species, including the number of the dorsal appendages (embryo respirators), and the presence or absence of a dorsal ridge (a lumen-like structure along the dorsal side of the eggshell). It was previously shown that changes in EGFR and BMP signaling are consistent with the morphological differences observed among the eggshells of Drosophila species. Here, we aim to study a new morphology, the respiratory stripe, featured on the eggshell of Scaptomyza anomala and Scaptomyza elmoi. These species are close relatives to Hawaiian Drosophila species. This thesis includes the characterization of eggshells’ morphologies, the spatiotemporal changes in EGFR and BMP signaling, and determination of some aspects of patterning changes related to the eggshells of S. anomala and S. elmoi.M.S.Includes bibliographical referencesby Alessio S. Russomann