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  • 2000-2004  (22)
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  • 1
    Electronic Resource
    Electronic Resource
    Iron and contact with host cells induce expression of adhesins on surface of Trichomonas vaginalis (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 47 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The proteins AP65, AP51, AP33 and AP23 synthesized by Trichomonas vaginalis organisms in high iron play a role in adherence. Multigene families encode enzymes of the hydrogenosome organelles, which have identity to adhesins. This fact raises questions regarding the compartmentalization of the proteins outside the organelle and about the interactions of adhesins with host cells. Data here demonstrate the presence of the proteins outside the organelle under high-iron conditions. Fluorescence and immuno-cytochemical experiments show that high-iron-grown organisms coexpressed adhesins on the surface and intracellularly in contrast with low-iron parasites. Furthermore, the AP65 epitopes seen by rabbit anti-AP65 serum that blocks adherence and detects surface proteins were identified, and a mAb reacting to those epitopes recognized the trichomonal surface. Two-dimensional electrophoresis and immunoblot of adhesins from surface-labelled parasites provided evidence that all members of the multigene family were co-ordinately expressed and placed on the trichomonal surface. Similar two-dimensional analysis of proteins from purified hydrogenosomes obtained from iodinated trichomonads confirmed the specific surface labelling of proteins. Contact of trichomonads with vaginal epithelial cells increased the amount of surface-expressed adhesins. Moreover, we found a direct relationship between the levels of adherence and amount of adhesins bound to immortalized vaginal and ureter epithelial cells, further reinforcing specific associations. Finally, trichomonads of MR100, a drug-resistant isolate absent in hydrogenosome proteins and adhesins, were non-adherent. Overall, the results confirm an important role for iron and contact in the surface expression of adhesins of T. vaginalis organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03366.x
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  • 2
    Electronic Resource
    Electronic Resource
    Contributions of the Axostyle and Flagella to Closed Mitosis in the Protists Tritrichomonas foetus and Trichomonas vaginalis (2000)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 47 (2000), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Tritrichomonas foetus and Trichomonas vaginalis are protists that undergo closed mitosis: the nuclear envelope remains intact and the spindle remains extranuclear. Here we show, in disagreement with previous studies, that the axostyle does not disappear during mitosis but rather actively participates in it. We document the main structural modifications of the cell during its cell cycle using video enhanced microscopy and computer animation, bright field light microscopy, confocal laser scanning microscopy, and scanning and transmission electron microscopy. We propose six phases in the trichomonad's cell cycle: an orthodox interphase, a pre-mitotic phase, and four stages during the cell division process. We report that in T. foetus and T. vaginalis: a) all skeletal structures such as the costa, pelta-axostyle system, basal bodies, flagella, and associated filaments of the mastigont system are duplicated in a pre-mitotic phase; b) the axostyle does not disappear during mitosis, otherwise playing a fundamental role in this process; c) axostyles participate in the changes in the cell shape, contortion of the anterior region of the cell, and karyokinesis; d) flagella are not under assembly during mitosis, as previously stated by others, but completely formed before it; and e) cytokinesis is powered in part by cell locomotion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2000.tb00077.x
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  • 3
    Electronic Resource
    Electronic Resource
    The release of secretory vesicle in encysting Giardia lamblia (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 235 (2004), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Giardia is an intestinal parasite that undergoes adaptation for survival outside the host. It secretes an extracellular cyst wall using a poorly understood process. An encystation-specific secretory vesicle (ESV) was previously described containing cyst wall proteins. The process of release of these vesicles has been suggested to occur after fragmentation of large ESV in small secretory vesicles, followed by exocytosis, but it was not demonstrated. The release of the ESV was studied by transmission electron microscopy. It was observed: (1) the moment of vesicle release; (2) that a large vesicle is exocytosed and does not fragment into small vesicles; (3) membrane fusion is distinct from traditional exocytosis since it is incomplete; (4) the occurrence of membrane fragmentation and that those membranes reseal to form ghosts; (5) these membrane ghosts may be endocytosed, adhered to flagellar surface or/and form empty vesicles in the extracellular medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2004.tb09570.x
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  • 4
    Electronic Resource
    Electronic Resource
    Centrin in Giardia lamblia– ultrastructural localization (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 233 (2004), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Giardia lamblia is a multiflagellar parasite and one of the earliest diverging eukaryotic cells. It possesses a complex cytoskeleton based on different groups of microtubular structures – a ventral adhesive disc, four pairs of flagella, a median body and funis. Centrin is an important member of the EF-hand family of calcium-binding proteins, and it is known to show calcium-sensitive contractile behaviour. In the present study, we performed an ultrastructural localization of centrin in G. lamblia using several monoclonal antibodies to centrin. Microtubular structures such as the basal bodies, all the flagella axonemes, the adhesive disc, funis, and the median bodies presented positive labelling to centrin. In addition, the dense rods also demonstrated positive labelling. These results show that centrin is located in key positions related to microtubules. The role of centrin in these dynamic regions is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/j.femsle.2004.01.043
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  • 5
    Electronic Resource
    Electronic Resource
    Trichomonas vaginalis: observation of coexistence of multiple viruses in the same isolate (2002)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 215 (2002), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Trichomonas vaginalis is a flagellated, parasitic protozoan that inhabits the urogenital tract of humans. Some isolates of T. vaginalis are infected with a double-stranded RNA (dsRNA) virus, which was described in the literature as homogeneous icosahedral viral particles with an isometric symmetry and 33 nm in diameter. This study examined in detail the viral particles in T. vaginalis isolate 347 and describes a heterogeneous population of viral particles. The different dsRNA viruses were only observed after a change in the technique. The sample was prepared by the negative staining carbon-film method directly onto freshly cleft mica. The detected viruses ranged in size from 33 to 200 nm. Among the shapes observed were filamentous, cylindrical, and spherical particles. These results show that T. vaginalis may be a reservoir for several different dsRNA viruses simultaneously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2002.tb11391.x
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  • 6
    Electronic Resource
    Electronic Resource
    The fine structure of acidocalcisomes in Trypanosoma cruzi (2000)
    Springer
    Parasitology research 86 (2000), S. 373-384 
    Details
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Trypanosoma cruzi survives in vertebrate and invertebrate hosts and has developed mechanisms that allow it to adapt to changes in the microenvironment such as temperature, pH, and ionic composition. Most of its calcium is concentrated in an organelle named the acidocalcisome, which is acidified by a (V-H+)-adenosine triphosphatase and has H+/Ca2+ countertransportation for calcium uptake. In this work, acidocalcisomes were examined using different transmission electron microscopy techniques. In thin sections of different stages, acidocalcisomes presented a circular shape with an electron-dense inclusion containing P3−, Ca2+, Na+, Mg2+, K+, and Zn2+. They could be distinguished from gold-labeled albumin-containing reservosomes in whole epimastigotes, and a morphometric analysis showed higher amounts of these organelles in amastigotes as compared with epimastigotes and trypomastigotes. It is possible that this variation in the amount of acidocalcisomes in the different evolutive stages could reflect adaptation mechanisms used by the parasite to survive and multiply in different environmental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004360050682
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  • 7
    Electronic Resource
    Electronic Resource
    Transient invagination of flagella by Tritrichomonas foetus (2000)
    Springer
    Parasitology research 86 (2000), S. 699-709 
    Details
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We describe an experimental system for the study of rapid and reversible formation of pseudocysts, which are spherical forms that lack a true cyst wall, by Tritrichomonas foetus, a trichomonad parasite of the bovine genitourinary tract. It highlights the dynamics of the plasma membrane and cytoskeleton of this parasite, which is perpetually devoid of any sort of protective cell wall, and can reflect a responsive survival mechanism. We have found that cooling of axenic cultures of T. foetus from their normal 37 °C to below about 16 °C can trigger pseudocyst formation. The three anterior flagella and the single recurrent flagellum can be fully internalized within 1–3 min at 37 °C, with the axonemes and flagellar membranes remaining intact within the cell body. Electron microscopy confirms that the internalized flagella are surrounded by a separate membrane. At 37 °C the internalized flagella can resume beating movements and become externalized as quickly as within 10 min. We have begun to elucidate the mechanisms of this unusual phenomenon, characterizing its temperature dependence and exploring the effects of agents that interfere with various aspects of the cytoskeleton, phagocytosis, endocytosis, and exocytosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008555
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  • 8
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    Pseudocysts in Trichomonads – New Insights (2003)
    Elsevier
    Details
    Publication Date: 2003-10-01
    Print ISSN: 1434-4610
    Electronic ISSN: 1618-0941
    Topics: Biology
    Published by Elsevier
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  • 9
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    Visualization of the funis of Giardia lamblia by high-resolution field emission scanning electron microscopy—new insights (2004)
    Elsevier
    Details
    Publication Date: 2004-08-01
    Print ISSN: 1047-8477
    Electronic ISSN: 1095-8657
    Topics: Biology
    Published by Elsevier
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  • 10
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    Hydrogen peroxide induces caspase activation and programmed cell death in the amitochondrial Tritrichomonas foetus (2003)
    Springer
    Details
    Publication Date: 2003-08-01
    Print ISSN: 0018-2222
    Electronic ISSN: 1432-119X
    Topics: Biology , Medicine
    Published by Springer
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