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[en] In the unicellular parasite Trypanosoma brucei, the causative agent of human African sleeping sickness, complex swimming behavior is driven by a flagellum laterally attached to the long and slender cell body. Using microfluidic assays, we demonstrated that T. brucei can penetrate through an orifice smaller than its maximum diameter. Efficient motility and penetration depend on active flagellar beating. To understand how active beating of the flagellum affects the cell body, we genetically engineered T. brucei to produce anucleate cytoplasts (zoids and minis) with different flagellar attachment configurations and different swimming behaviors. We used cryo-electron tomography (cryo-ET) to visualize zoids and minis vitrified in different motility states. Here, we showed that flagellar wave patterns reflective of their motility states are coupled to cytoskeleton deformation. Based on these observations, we propose a mechanism for how flagellum beating can deform the cell body via a flexible connection between the flagellar axoneme and the cell body. Lastly, this mechanism may be critical for T. brucei to disseminate in its host through size-limiting barriers.
[en] RAB proteins are small GTPases involved in exocytic and endocytic pathways of eukaryotic cells, controlling vesicle docking and fusion. RABs show a remarkable specificity in subcellular localization, so they can be used as molecular markers for studying protein trafficking in Trypanosoma cruzi, the causal agent of Chagas' disease. RAB5 is a component of early endosomes. It has been identified in kinetoplastids such as Trypanosoma brucei and Leishmania donovani. In this work, we describe the characterization of the complete coding sequence of a RAB5 gene homologue in T. cruzi (TcRAB5, GenBank Accession No. AY730667). It is present as a single copy gene, located at chromosomal bands XIII and XIV. TcRAB5 shares the highest degrees of similarity (71%) and identity (63%) with Trypanosoma brucei rhodesiense RAB5a and contains all five characteristic RAB motifs. TcRAB5 is transcribed as a single 1.5kb mRNA in epimastigotes. Its transcript was also detected in the other two forms of the parasite, metacyclic trypomastigotes and spheromastigotes. The recombinant TcRAB5 protein was able to bind and hydrolyze GTP. The identification of proteins involved in T. cruzi endo- and exocytic pathways may generate cellular compartment markers, an invaluable tool to better understand the vesicular transport in this parasite
[en] Observations on flourishing resident herds and trade cattle within the Awka Zone in northern fringes of the rain forest belt of Anambra State, Nigeria, prompted this current study on the status of trypanosomiasis and tsetse distribution in the zone. Parts of the greater Mamu forest reserve and seven other forest patches covering 800 km2 were studied. Except for two small forests others were infested with Glossina palpalis palpalis. 84 flies were captured, out of which one had mature Trypanosoma vivax infection. 443 cattle were examined in two slaughterhouses for trypanosomes. Only four of them had parasites that were identified morphologically as T. vivax. Deforestation due to industrialisation and development of the hinterland could contribute to lowered intensity of infection in an area originally thought very hazardous for livestock keeping. (author)
[en] A radioactive Western blotting technique was developed by which the reactivity of Immunoglobulins (IGs) from different classes to both membrane radiolabelled and internal parasite antigens is simultaneously identified. The method includes radioiodination of parasites, polypeptide fractionation by SDS-PAGE, Western-blot transfer and autoradiography of the immunoblots developed with anti-Igs conjugates labelled with enzymes. The analysis is then performed by the comparison of common bands on the autoradiograms and the respective substrate stained nitrocellulose blots. This technique was used to analyse. T.cruzi trypomastigote surface labelled antigens reactive to IgM, IgA and IgC specific antibodies. A different pattern of reactivity with acute Chagas disease patients sera was thus obtained. (author)
[en] Series of ring-substituted 3-hydroxynaphthalene-2-carboxanilides were screened for their in vitro activity against wild-type S427 (bloodstream form) of Trypanosoma brucei brucei. 3-Hydroxy-N-(3-trifluoromethylphenyl)- and 3-hydroxy-N-(4-trifluoromethylphenyl)naphthalene-2-carboxamides showed the highest biological activity (MIC = 1.56 and 2.08 µmol/dm3, respectively). Antitrypanosomal activity was correlated with the experimentally determined lipophilicity and acid–base dissociation constants of the compounds as well as with the calculated electronic properties of individual anilide substituents expressed as Hammett’s σ parameters. The substitution in the meta- or para-position of anilide of derivatives with higher lipophilicity by an electron-withdrawing moiety is favourable for higher activity. The optimum thermodynamic pKaT value was found to be ca. 7.5. The structure–activity relationships of all compounds are discussed. Graphical abstract: .
[en] The conservation of black rhinoceros (Diceros bicornis) in Kenya involves the translocation of rhinoceros to protected sanctuaries, e.g. the recently enlarged 69 km2 sanctuary at Ngulia in Tsavo West National Park. As the black rhinoceros is known to be particularly susceptible to infection with Trypanosoma brucei, there is a strong possibility that the stress of translocation will induce health problems that would not normally occur in resident populations. Similarly, the movement of animals born in tsetse-free areas to tsetse-infested areas may result in trypanosomiasis problems because of loss of immune protection in the absence of challenge in early life. Finally, there is some concern over the possibility of facilitating genetic exchange in T. brucei through the artificial movement of animals over long distances into novel environments. To aid in the development of prudent management practices, we initiated baseline studies on tsetse distribution and trypanosomiasis at the Ngulia sanctuary. To date, we have completed a dry season survey of tsetse distribution over a 125 km2 area centred on the sanctuary and have characterized the nature of the trypanosomiasis challenge in different areas. Trypanosomiasis challenge at Ngulia involves a variety of Trypanosoma spp. Nevertheless, an unusual finding is the lack of diversity in Nannomonas parasites, with most belonging to the savannah group of T. congolense