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Sarikaya, Didem P.

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Sarikaya

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Didem P.

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Sarikaya, Didem P.

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Now showing 1 - 3 of 3
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    Publication
    The Hippo Pathway Regulates Homeostatic Growth of Stem Cell Niche Precursors in the Drosophila Ovary
    (Public Library of Science, 2015) Sarikaya, Didem P.; Extavour, Cassandra
    The Hippo pathway regulates organ size, stem cell proliferation and tumorigenesis in adult organs. Whether the Hippo pathway influences establishment of stem cell niche size to accommodate changes in organ size, however, has received little attention. Here, we ask whether Hippo signaling influences the number of stem cell niches that are established during development of the Drosophila larval ovary, and whether it interacts with the same or different effector signaling pathways in different cell types. We demonstrate that canonical Hippo signaling regulates autonomous proliferation of the soma, while a novel hippo-independent activity of Yorkie regulates autonomous proliferation of the germ line. Moreover, we demonstrate that Hippo signaling mediates non-autonomous proliferation signals between germ cells and somatic cells, and contributes to maintaining the correct proportion of these niche precursors. Finally, we show that the Hippo pathway interacts with different growth pathways in distinct somatic cell types, and interacts with EGFR and JAK/STAT pathways to regulate non-autonomous proliferation of germ cells. We thus provide evidence for novel roles of the Hippo pathway in establishing the precise balance of soma and germ line, the appropriate number of stem cell niches, and ultimately regulating adult female reproductive capacity.
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    Counting in oogenesis
    (Springer Science + Business Media, 2011) Green, Delbert Andre; Sarikaya, Didem P.; Extavour, Cassandra
    The determination of a precise number of cells within a structure and of a precise number of cellular structures within an organ is critical for correct development in animals and plants. However, relatively little is known about the molecular mechanisms that ensure that these numbers are achieved. We discuss counting mechanisms that operate during ovarian development and oogenesis.
  • Publication
    The Effect of Development and Ecology on the Evolution of Ovary Size in Drosophila
    (2015-05-20) Sarikaya, Didem P.; Extavour, Cassandra G.; Kramer, Elena; Perrimon, Norbert; Haig, David
    How the size of an organ is established and altered during evolution is poorly understood. The ovary of fruit flies of the genus Drosophila serves as an interesting model for understanding organ size evolution, as the number of egg-producing structures called ovarioles determines the ovary’s functional ‘size’. Species with more ovarioles can lay more eggs, and ovariole number can evolve rapidly between closely related species. However, the developmental and genetic mechanisms that determine and alter ovariole number were poorly characterized at the beginning of this thesis. I first analyzed the developmental basis of plasticity and species-specific ovariole number changes in D. melanogaster and closely related species. This analysis revealed distinct developmental mechanisms that alter ovariole number via changes in one cell type (terminal filament cells) in the developing ovary. To characterize the genetic mechanisms underlying proliferation patterns and potential cell-type interactions within the ovary, I then studied the role of the Hippo pathway in the somatic and germ cells of D. melanogaster. I uncovered a complex interaction between somatic cells and germ line cells, where proportional growth of these cell types is maintained by the Hippo pathway via interactions with the EGFR and JAK/STAT pathways. Finally, I expanded this work to investigate the physical, ecological, and developmental parameters that influence ovariole number evolution in Hawaiian Drosophila, where previous studies suggested that ovariole number correlated with larval food substrate. I describe my ongoing efforts to test correlations of ecology and ovariole number in a phylogenetic context in Hawaiian Drosophila. Primary differences in ovariole number between species occur through changes in cell number.