• Login
    • Submit
    View Item 
    •   Repository Home
    • UT Electronic Theses and Dissertations
    • UT Electronic Theses and Dissertations
    • View Item
    • Repository Home
    • UT Electronic Theses and Dissertations
    • UT Electronic Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    The cellular and molecular mechanisms underlying ventral midline patterning and morphogenesis in the amniote midbrain

    Icon
    View/Open
    BROWN-DISSERTATION-2015.pdf (2.443Mb)
    Date
    2015-12
    Author
    Brown, Charmaine Yvonne
    0000-0001-6242-7243
    Share
     Facebook
     Twitter
     LinkedIn
    Metadata
    Show full item record
    Abstract
    The floorplate (FP) is located at the ventral midline of the developing neural tube, and is involved in patterning and specification of ventral and dorsal cell fates. The FP has long been known to pattern ventral cell fates via secretion of Sonic Hedgehog (SHH). However, the mechanism by which the FP is specified is controversial due to species variations where SHH is differentially required for FP specification in fish and mouse. In Chapter 3, we show that, similar to the fish, the amniote anterior neural plate can be divided into medial (MFP) and lateral (LFP) subdivisions which differentially require SHH and FOXA2 for their specification, and that FOXA2, but not SHH, is sufficient to induce the entire midbrain FP pattern. In addition, we show that all three midbrain signaling centers are physically continuous and interconvertible, with their specification depending on SHH. Prior to the expression of SHH protein, the ventral midline undergoes a morphogenetic event called median hinge point (MHP) formation which buckles the flat neural plate and lifts the neural folds which ultimately fuse into a cylindrical neural tube. Previous studies in the lab have shown that Bone Morphogenetic Proteins (BMP) modulate HP formation. HP formation involves dynamic cell-shape changes, which result in HP cells becoming wedge-shaped. Multiple mechanisms (constriction of the adherens belt via cytoskeletal and junctional remodeling, and polarized endocytosis) have been proposed to explain this shape change. However, they do not explain how reduction in apical area can be achieved in the amniote neural plate where cells are bipolar and only slender processes contact the apical surface in non-mitotic cells. In Chapter 4, we develop an early electroporation technique which is used in Chapter 5 to visualize HP formation in real time as part of a novel 3D explant system. Our results suggest that BMP attenuation regulates cell cycle progression by increasing the duration of G1 and S phases, and causes a subset of cells to prematurely exit the cell cycle and undergo sub-apical G2-M transition, similar to what is seen in the MHP where there is reduced mitotic index and cells undergo mitosis sub-apically.
    Department
    Cellular and Molecular Biology
    Subject
    Floor plate
    Midbrain–hindbrain boundary
    Roof plate
    SHH
    FOXA2
    Signaling centers
    Neural plate
    Gene misexpression
    Gene manipulations
    In ovo electroporation
    BMP
    Hinge point
    Cell cycle
    URI
    http://hdl.handle.net/2152/32917
    Collections
    • UT Electronic Theses and Dissertations
    University of Texas at Austin Libraries
    • facebook
    • twitter
    • instagram
    • youtube
    • CONTACT US
    • MAPS & DIRECTIONS
    • JOB OPPORTUNITIES
    • UT Austin Home
    • Emergency Information
    • Site Policies
    • Web Accessibility Policy
    • Web Privacy Policy
    • Adobe Reader
    Subscribe to our NewsletterGive to the Libraries

    © The University of Texas at Austin

    Browse

    Entire RepositoryCommunities & CollectionsDate IssuedAuthorsTitlesSubjectsDepartmentThis CollectionDate IssuedAuthorsTitlesSubjectsDepartment

    My Account

    Login

    Information

    AboutContactPoliciesGetting StartedGlossaryHelpFAQs

    Statistics

    View Usage Statistics
    University of Texas at Austin Libraries
    • facebook
    • twitter
    • instagram
    • youtube
    • CONTACT US
    • MAPS & DIRECTIONS
    • JOB OPPORTUNITIES
    • UT Austin Home
    • Emergency Information
    • Site Policies
    • Web Accessibility Policy
    • Web Privacy Policy
    • Adobe Reader
    Subscribe to our NewsletterGive to the Libraries

    © The University of Texas at Austin