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The lab approaches questions of pattern formation and cell fate specification in the fruit fly Drosophila melanogaster. Our current interests are the mechanisms underlying the patterning of the embryonic dorsal-ventral (D/V) axis and the asymmetric self-renewal divisions of adult stem cells.
The main focus of lab has been on the role of the Bone Morphogenetic Protein (BMP) family member Decapentaplegic (Dpp) in patterning the D/V axis. Over the years, my laboratory discovered the conservation of dorsal-ventral patterning mechanisms between arthropods and chordates, identified the function of the Spemann organizer in Xenopus, showed that a non-linear feedback circuit resulted in a bistable pattern of BMP signaling during Drosophila D/V patterning, identified a genetic network that confers robustness to the D/V patterning system in Drosophila, and was involved in a collaboration to demonstrate that spatial-temporal changes in the BMP gradient drove morphological changes during Dipteran evolution.
We have also investigated the processes responsible for the maintenance of the germ line stem cells (GSCs) in the adult ovary. The GSCs are present in a niche composed of non-dividing somatic cells, and these cells secrete BMP ligands necessary for GSC maintenance. The GSC has high levels of BMP signaling, while its sister cell, the Cystoblast, has low levels of BMP signaling and begins the process of differentiation. We have identified multiple redundant mechanisms that aid in creating this dichotomy in BMP signaling between sister cells. In particular, we have shown that interactions between the GSC and the surrounding niche cells create an intrinsic polarity in the GSC that both controls the plane of GSC division and elevates responsiveness to Dpp within the GSC. Recently, we have shown that GSCs can be maintained in the niche with very low levels of BMP signaling, which has implications for stem cell maintenance during aging.