...Paul T. Manna; Lael D. Barlow; Inmaculada Ramirez-Macias; Emily K. Herman; Joel B. Dacks ABSTRACT Contractile vacuoles (CVs), enigmatic osmoregulatory organelles, share common characteristics, such as a requirement for RAB11 and high levels of V-ATPase. These commonalities suggest a conserved...

...Feifei Xu; Xiaoan Wu; Lin-Hua Jiang; Hucheng Zhao; Junmin Pan ABSTRACT Fresh water protozoa and algae face hypotonic challenges in their living environment. Many of them employ a contractile vacuole system to uptake excessive water from the cytoplasm and expel it to the environment to achieve...

...Sayantanee Niyogi; Veronica Jimenez; Wendell Girard-Dias; Wanderley de Souza; Kildare Miranda; Roberto Docampo ABSTRACT The contractile vacuole complex (CVC) of Trypanosoma cruzi , the etiologic agent of Chagas disease, collects and expels excess water as a mechanism of regulatory volume decrease...

... phagocytic cups, in foci connecting dividing cells during the final stage of cytokinesis and most prominently at the osmoregulatory contractile vacuole (CV). Consistently, IBARa-null mutants displayed defects in CV formation and discharge, growth, phagocytosis and mitotic cell division, whereas filopodia...

...Karin Komsic-Buchmann; Lisa Marie Stephan; Burkhard Becker Summary Contractile vacuoles (CVs) are essential for osmoregulation in many protists. To investigate the mechanism of CV function in Chlamydomonas , we isolated novel osmoregulatory mutants. Four of the isolated mutant cell lines carried...

... why SecA is required for motility, we examined membrane trafficking in the mutant. Plasma membrane circulation is rapidly inhibited at the restrictive temperature and the cells acquire a prominent vesicle. Organelle-specific markers show that this is an undischarged contractile vacuole, and we found...

..., are on contractile vacuoles. MEGAP1 – /2 – cells empty their contractile vacuoles less efficiently than normal and consequently have three times the usual number. GFP-tagged MEGAP1 localises to tubules of the contractile vacuole network and when vacuoles start to empty they recruit cytosolic GFP-MEGAP1. Mutants...

...Valentina Mercanti; Cédric Blanc; Yaya Lefkir; Pierre Cosson; François Letourneur The mechanisms responsible for the targeting of transmembrane integral proteins to the contractile vacuole (CV) network in Dictyostelium discoideum are unknown. Here we show that the transfer of the cytoplasmic...

... in Paramecium . Green fluorescent protein (GFP) fusion proteins allowed a clear subcellular localization of c- and F-subunits in the contractile vacuole complex of the osmoregulatory system and in food vacuoles. Several other organelles were also detected, in particular dense core secretory granules...

...Margaret Clarke; Jana Köhler; Quyen Arana; Tongyao Liu; John Heuser; Günther Gerisch The vacuolar H + -ATPase (V-ATPase) is a multi-subunit enzyme that plays important roles in eukaryotic cells. In Dictyostelium , it is found primarily in membranes of the contractile vacuole complex, where...

... was exclusively associated with the ATPase proton pump-rich contractile vacuole membrane system, consisting of a reticular network and bladder-like vacuoles. Video microscopy of cells expressing GFP-DdRab11 revealed that this Rab was associated with contractile vacuolar bladders undergoing formation, fusion...

... of a contractile vacuole with the cell membrane. During protrusion extension, a patch of the contractile vacuole membrane stayed undiffused on the leading edge of the protrusion for over 30 seconds. Protrusion formation was not inhibited by high osmolarity of the external medium (at least up to 400 mosM...

...Takashi Tominaga; Yutaka Naitoh; Richard D. Allen ABSTRACT The contractile vacuole complex of the fresh water protozoan Paramecium multimicronucleatum exhibits periodic exocytotic activity. This keeps cytosolic osmolarity at a constant value. The contractile vacuole, the central exocytotic vesicle...

...John Moniakis; M. Barrie Coukell; Agnes Janiec ABSTRACT In Dictyostelium discoideum , the Ca 2+ -ATPase, PAT1, is localized to membranes of the contractile vacuole and its expression is upregulated substantially when the cells are grown in Ca 2+ -rich medium. In this study, we have analyzed...

...Lesly A. Temesvari; Juan M. Rodriguez-Paris; John M. Bush; Linyi Zhang; James A. Cardelli ABSTRACT We have investigated the effects of Concanamycin A (CMA), a specific inhibitor of vacuolar type H + -ATPases, on acidification and function of the endo-lysosomal and contractile vacuole (CV) systems...

... in targeting the enyzme or modulating its function. In amoebae of Dictyostelium discoideum , proton pumps with a 100 kDa subunit are found in membranes of the contractile vacuole complex, an osmoregulatory organelle. We cloned the cDNA that encodes this 100 kDa protein and found that its sequence predicts...

...Masaki Ishida; Agnes K. Fok; Marilynn S. Aihara; Richard D. Allen ABSTRACT To study the effect of hyperosmotic stress on the structure and function of the contractile vacuole complex of Para- mecium multimicronucleatum , we employed two different monoclonal antibody markers: one to a decorated...

...Qianlong Zhu; Tongyao Liu; Margaret Clarke ABSTRACT In amoebae of the eukaryotic microorganism Dictyostelium discoideum , calsmodulin is greatly enriched on membranes of the contractile vacuole complex, an osmoregulatory organelle. Antibodies specific for Dictyostelium calmodulin were used...