• Login as Editor
    View Item 
    •   Yeshiva Academic Institutional Repository
    • Albert Einstein College of Medicine (AECOM)
    • Albert Einstein College of Medicine: Doctoral Dissertations
    • View Item
    •   Yeshiva Academic Institutional Repository
    • Albert Einstein College of Medicine (AECOM)
    • Albert Einstein College of Medicine: Doctoral Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    STUDIES ON EXOCYTOSIS IN PARAMECIUM TETRAURELIA: ROLE OF DIVALENT CATIONS AND PROTEIN PHOSPHORYLATION (PHOSPHOPROTEIN, CALCIUM-DEPENDENT, PROTOZOA, TRICHOCYST, STIMULUS-SECRETION COUPLING)

    Thumbnail
    Date
    1985
    Author
    GILLIGAN, DIANA MARY
    Metadata
    Show full item record
    Abstract
    The cortex of Paramecium contains thousands of membrane-bound secretory organelles called trichocysts, whose content, the trichocyst matrix (tmx), is released in response to secretagogues (e.g. picric acid, paranitrophenol or Alcian Blue). Studies with light microscopy, freeze fracture (FFEM) and transmission (TEM) electron microscopy show that high extracellular Mg('2+) inhibits two morphologically characterized secretory events, membrane fusion (exocytosis) and tmx expansion, suggesting that Ca('2+) is required for both.;Exocytotic sites in the plasma membrane are characterized in FFEM with specific intramembrane particle arrays (rosettes). A temperature sensitive secretory mutant, nd 9, lacks rosettes and does not secrete when grown at 27(DEGREES)C, but assembles rosettes and does secrete when grown at 18(DEGREES)C. The divalent cation ionophore A23187, which bypasses physiologically regulated Ca('2+) influx, triggers normal secretion in wild type (wt) cells, but only tmx expansion (without membrane fusion) in non-permissive mutants, suggesting that the rosette particles represent membrane components specifically required for exocytosis.;Exocytosis is correlated with the Ca('2+)-dependent dephosphorylation of a 65,000 M(,r) polypeptide (65K) in two types of experiment: (1) high extracellular Mg('2+) inhibits picric acid-induced secretion and dephosphorylation of 65K in wt cells, and (2) nd 9 permissive cells secrete and dephosphorylate 65K in response to picric acid, whereas nd 9 non-permissive cells do not. Thus the presence of an assembled rosette is required for the Ca('2+)-dependent dephosphorylation of 65K.;The effects of paranitrophenol and Alcian Blue on membrane fusion, tmx expansion and dephosphorylation of 65K in wt and nd 9 mutants are also examined. Further information about the stimulus-sensitive phosphoprotein is obtained from subcellular fractionation, in vitro phosphorylation, two dimensional gel electrophoresis, and phosphoamino acid identification. Results suggest that the 65K phosphoprotein may be a component of the molecular pathway coordinating exocytosis in response to extracellular stimulation.
    Permanent Link(s)
    https://yulib002.mc.yu.edu/login?url=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqm&rft_dat=xri:pqdiss:8616973
    https://hdl.handle.net/20.500.12202/3117
    Collections
    • Albert Einstein College of Medicine: Doctoral Dissertations [1674]

    Yeshiva University Libraries copyright © 2021  DuraSpace
    YAIR Self-Deposit | YAIR User's Guide | Take Down Policy | Contact Us
    Yeshiva University
     

     

    Browse

    AllCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    Login as Editor

    Statistics

    View Usage Statistics

    Yeshiva University Libraries copyright © 2021  DuraSpace
    YAIR Self-Deposit | YAIR User's Guide | Take Down Policy | Contact Us
    Yeshiva University