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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 42 (1995), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Tritrichomonas foetus is a flagellated protozoon found in urogenital tract of cattle. Its free movement in liquid medium is powered by the coordinated movement of three flagella projecting towards the anterior region of the cell, and one recurrent flagellum that forms a junction with the cell body and ends as a free projection in the posterior region of the cell. We have used video microscopy and digital image processing to analyze the relationships between the movements of these flagella. The anterior flagella beat in a ciliary type pattern displaying effective and recovery strokes, while the recurrent flagellum beats in a typical flagellar wave form. One of the three anterior flagella has a distinctive pattern of beating. It beats straight in its forward direction as opposed to the ample beats performed by the others. Frequency measurements obtained from cells swimming in a viscous medium shows that the beating frequency of the recurrent flagelium is approximate twice the frequency for the three anterior flagella. We also observed that the costa and the axostyle do not show any active motion. On the contrary, they form a cytoskeletal base for the anchoring and orientation of the flagella.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 39 (1992), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The quick-freezing and freeze-etching techniques were used to analyze surface domains of Tritrichomonas foetus. The surface of the protozoan body was not smooth, presenting surface projections, except on the flagellar surface. Images of the actual surface of the anterior flagella revealed the presence of intramembranous particles that form rosettes, as observed on the protoplasmic fracture face. They may represent integral transmembrane proteins exposed at the cell surface. Surface specializations were also observed at the flagella base and where the recurrent flagellum attaches to the cell body.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 30 (1983), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Fine structural studies of the hydrogenosomes of Tritrichomonas foetus using an improved fixative reveal that they are enclosed by two closely apposed 6 nm membranes, which separate at some regions forming a large intramembranous vacuole where Ca++-binding sites are located. Fixation of the cells in a glutaraldehyde solution containing 5 mM CaCl2 and postfixation in an osmium tetroxide-potassium ferrocyanide solution led to the appearance of a reaction product associated with certain regions of the membrane of the hydrogenosomes and in the cisternae of the endoplasmic reticulum, in the recurrent flagellum, and in the plasma membrane. Treatment of ultrathin sections with EGTA removed the reaction product. These results, in association with others previously described, indicate the existence of several similarities between the hydrogenosomes and the mitochondria.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 29 (1982), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Freeze-fracture techniques reveal differences in fine structure between the anterior three flagella of Tritrichomonas foetus and its recurrent flagellum. The anterior flagella have rosettes of 9–12 intramembranous particles on both the P and E faces. The recurrent flagellum lacks rosettes but has ribbon-like arrays of particles along the length of the flagellum, which may be involved in the flagellum's attachment to the cell body. This flagellum is attached to the membrane of the cell body along a distinct groove that contains few discernible particles. Some large intramembranous particles are visible on the P face of the cell body membrane at the point where the flagellum emerges from the cell body. The randomly distributed particles on the P and E faces of the plasma membrane have a particle density of 919/μm2 and 468/μm2 respectively, and there are areas on both faces that are devoid of particles. Freeze-fracture techniques also reveal numerous fenestrations in the membrane of the Golgi complex and about 24 pores per μm2 in the nuclear. membrane.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 28 (1981), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The cell surface of Tritrichomonas foetus was characterized by using 18 highly purified lectins with specificities for N-acetyl glucosamine, N-acetyl galactosamine, galactose, mannose, and sialic acid. The specificity of the lectin-induced cell agglutination was verified by inhibition of the agglutination with the specific sugars. By using cytochemical techniques associated with electron microscopy, carbohydrates were detected on the cell surface of T. foetus. The following techniques were used: periodic acid-thiosemicarbazide-silver proteinate, concanavalin A-horseradish peroxidase, and ruthenium red. Anionic sites were detected on the cell surface of the protozoan at pH's 1.8 and 7.2 with the use of colloidal iron hydroxide and cationized ferritin particles, respectively. The binding of colloidal iron particles, as well as the agglutination induced by the lectin from Limulus polyphemus, indicated the presence of sialic acid on the cell surface of T. foetus.
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  • 6
    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.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 45 (1998), S. 0 
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Monocercomonas sp. from the wood-snake Tropidophis melanurus was studied using fast freezing of alive and fixed cells followed by freeze-fracture and deep-etching. Cytochemistry for enzymes (acid phosphatase, neutral phosphatase, and thiaminopyrophosphatase) and for carbohydrates and endocytosis of gold-labeled albumin were also performed. The Golgi complex is formed by 12-14 cisternae with typical cis and trans faces connected to a network of tubular and cisternal structures, and is positive for thiaminopyrophosphatase at the trans face. Intraluminal filamentous structures are seen connecting the two faces of the cisternae of the Golgi complex. Lysosomes appeared to contain acid and neutral phosphatases. Cytochemistry showed that lysosomes predominate among the unidentified vacuoles in the cytoplasm. Some vesicles are involved in the endocytic pathway, while others are derived from the Golgi complex. Hydrogenosomes have a rod-like or dumb-bell shape. Two of the anterior flagella present rosettes, when observed in replicas of freeze-fractured material, formed by circular arrangement of intramembranous particles on both P and E faces. The other anterior and the recurrent flagella do not show such rosettes but showed ribbon-like arrays of particles at the point where they emerge from the cell body.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 47 (2000), S. 0 
    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.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 235 (2004), S. 0 
    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.
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 233 (2004), S. 0 
    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.
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