Edna Freymuller

Bio: Edna Freymuller is an academic researcher from University of São Paulo. The author has contributed to research in topics: Flagellum & Acid phosphatase. The author has an hindex of 5, co-authored 7 publications receiving 334 citations.

Life Cycle and Culturing of Phytomonas serpens (Gibbs), a Trypanosomatid Parasite of Tomatoes

Abstract: Pure cultures of a trypanosomatid isolated from tomato fruits infected laboratory-raised tomatoes and nymphs of the hemipieran coreid Phthia picta. The flagellate could be transmitted back and forth from tomatoes to insects. Light and electron microscopy studies were done on culture, tomato and insect forms. Examination of enzymes of the ornithine-arginine metabolism revealed absence of arginase and presence of arginine deiminase and citrulline hydrolase. Monoclonal antibodies specific for Phytomonas spp. reacted positively with tomato and insect forms. Endonuclease digestion of the k-DNA of various Phytomonas spp. revealed a unique, distinctive pattern for the tomato flagellate. This flagellate thus seems to constitute a separate species of Phytomonas which we now call Phytomonas serpens (Gibbs).

Ultrastructural Differences Between Species of Trypanosomatids With and Without Endosymbionts1

Abstract: Species of trypanosomatids without endosymbionts (Leptomonas seymouri, L. collosoma, L. samueli, crithidia fasciculata, C. luciliae, C. acanthocephali, Herpetomonas megaseliae, H. mariadeanei, H. samuelpessoai, H. muscarum muscarum, Trypanosoma cruzi) and species of trypanosomatids with endosymbionts (Crithidia deanei, C. oncopelti, Blastocrithidia culicis) were comparatively studied by means of electron microscopy. Artificially aposymbiotic strains derived from species with symbiont were also included in the survey. Species with symbiont were found to differ in some ultrastructural aspects from the group of species without symbiont. Paraxial rods of flagella or intraflagellar structure were found exclusively in species without symbiont. Peripheral branching of mitochondria, accompanied by absence of subpellicular microtubules in sites where the mitochondrial branches are appressed to the cell membrane, were found exclusively in species with symbiont. Networks of kinetoplast DNA fibrils were found to be larger and looser in species with symbiont. Symbiont-free strains of species with symbiont retained the same morphological characteristics of their parental species.

Endosymbiont as supplier of ornithine carbamoyltransferase in a trypanosomatid

Abstract: IN spite of the widespread occurrence of intracellular bacteria-like symbionts in eukaryotic cells little is known about their function1–3. They are generally thought to offer some advantage to the host cell while benefiting from its ‘hospitality’, but their precise contribution is known in few cases. Flagellates that harbour endosymbionts provide excellent models for the analysis of this relationship. Three trypanosomatids, Crithidia oncopelti, C. deanei and Blastocrithidia culicis harbour endosymbionts whose bacteria-like nature has been confirmed morphologically and biochemically4–9. Unlike symbiont-free species10, those species do not require haemin for growth because the endosymbionts provide haemm-synthesising enzymes11. We now report that endosymbionts enable certain species of Crithidia to synthesise arginine from ornithine.

Cell Biology of Trypanosoma cruzi

Abstract: Publisher Summary Among the protozoa of the Trypanosomatidae family, a large number of species represent agents of diseases, such as Chagas' disease. This chapter reviews some aspects of the cell biology of Trypanosoma cruzi, giving emphasis to those aspects related to the ultrastructure of pathogenic protozoa. Protozoa of the Trypanosomatidae family show, during their, life cycle, several forms which can be easily identified by light microscopy in Giemsa-stained preparations. The chapter also explains the life cycle of T. cruzi. In the life cycle of T. cruzi, there are forms which are able to divide. There is one form, considered to be highly differentiated and responsible for the infectivity of these protozoa, which does not divide. It is highlighted that the trypomastigote form can transform into a rounded form which possesses a free flagellum. This form, which appears in the stomach, is able to transform into either short epimastigotes that start a process of multiplication in the intestinum or into long epimastigotes which move to the more posterior region of the digestive tract of the bug. Cell surface is also emphasized in the chapter.

Ciliary and Flagellar Membranes

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Intracellular trafficking and the parasitophorous vacuole of Leishmania mexicana-infected macrophages.

Abstract: The continued success of Leishmania as an intramacrophage parasite is dependent on its ability to survive within an acidic intracellular compartment, resist degradation by lysosomal hydrolases, exploit the host cell as a source of nutrients, and avoid the macrophage9s antigen-presenting capabilities. All these requirements are dependent on the properties of the parasitophorous vacuole in which Leishmania resides. This study shows that the vacuole possesses membrane proteins characteristic of a lysosome, and has MHC class II molecules. The trafficking of a variety of endocytic markers supports this finding. However, a temporal study up to 14 days post-infection indicates that, as it matures, the vacuole gains mannose 6-phosphate receptor, and becomes more accessible to endocytosed ligand, suggesting that the vacuole has functionally translocated from a lysosomal to late endosomal compartment. Endocytosed material was detected in the flagellar pocket and inside the amastigote, demonstrating parasite uptake of intra-vacuolar material. Careful analysis of amastigotes suggests that they avoid antigen presentation by their host cell by limiting the release of potential antigens. These findings significantly extend our understanding of the mechanisms employed by Leishmania to ensure its survival in the macrophage.