ULTRASTRUCTURAL DIFFERENCES BETWEEN SPECIES of TRYPANOSOMATIDS WITH and WITHOUT ENDOSYMBIONTS

ESCOLA PAULISTA MED,DEPT MICRO IMUNO & PARASITOL,São Paulo 04023,SP,BRAZILESCOLA PAULISTA MED,DEPT MICRO IMUNO & PARASITOL,São Paulo 04023,SP,BRAZILWeb of Scienc

ENDOSYMBIONT AS SUPPLIER of ORNITHINE CARBAMOYLTRANSFERASE in A TRYPANOSOMATID

ESCOLA PAULISTA MED,DEPT MICRO IMMUNO & PARASITOL,São Paulo,BRAZILESCOLA PAULISTA MED,DEPT MICRO IMMUNO & PARASITOL,São Paulo,BRAZILWeb of Scienc

Experimental murine chromoblastomycosis obtained from Fonsecaea pedrosoi isolate cultured for a long periodt

The present study aimed to describe F. pedrosoi propagules capable of causing chronic murine disease. Several changes in F. pedrosoi hyphae were identified in fungal cells cultured for a long period. Optical microscopy found many rounded cells with double-rigid melanin-rich walls. Terminal and intercalary chlamydoconidia were also frequently observed. Analyses of images from transmission electron microscopy (TEM) revealed several cells with walls composed of at least three layers and an outer layer enriched with melanin. Two groups of twenty BALB/c mice were subcutaneously infected in their footpads with F. pedrosoi cells at an inoculum concentration of approximately 1 x 10(4) cells/mL. In one group, long-term cultured F. pedrosoi cells were inoculated in one footpad, whereas in the other group, both footpads were infected. Active lesions were observed up to seven months post-infection, particularly in mice inoculated at two sites. After this period, animals were killed. Histological sections revealed characteristics bearing a strong resemblance to the human form of the disease such as tissue hyperplasia, granulomas with microabscesses and sclerotic cells. Based on this study, we identified fungal cells from old cultures capable of provoking chronic chromoblastomycosis under experimental conditions, especially when more than one site is infected

Intercellular junctions in rabbit eye ora serrata

The aim of this study was to describe and localize the intercellular junctions in the ora serrata region of albino and pigmented rabbit eyes. Eyes of albino and pigmented rabbits were fixed and processed for transmission electron microscopy. Light and electron microscope examination was carried out on semithin and ultrathin sections. the ora serrata region showed adherens, gap and tight junctions in the retinal and ciliary margins of albino and pigmented rabbit eyes. in the retinal margin, zonulae adherens between Muller cells and photoreceptors are associated with tight junctions. in the ciliary margin, epithelial cells are joined by adherens, gap and tight junctions localized between apical and apicolateral cell membranes. Tight junctions appear as zonulae occludens in the non-pigmented apicolateral cell membranes and as tight focal junctions between pigmented and non-pigmented apical cell membranes. Between the ciliary and retinal margins there are adherens and tight focal junctions which attach pigmented apical cell membranes to adjacent cells. There were no differences in the distribution of intercellular junctions between albino and pigmented rabbits.Universidade Federal de São Paulo, Dept Morphol, São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Electron Microscopy, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Morphol, São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Electron Microscopy, São Paulo, BrazilWeb of Scienc

LYSOSOMAL DEPLETION in MACROPHAGES FROM SPLEEN and FOOT LESIONS of LEISHMANIA-INFECTED HAMSTER

UNIV São Paulo,INST BIOMED,DEPT HISTOL & EMBRIOL,BR-05508 São Paulo,BRAZILWeb of Scienc

Detection of Campylobacter jejuni Invasion of HEp-2 Cells by Acridine Orange-Crystal Violet Staining

UNIV AUSTRAL CHILE,INST INMUNOL,VALDIVIA,CHILEUniversidade Federal de São Paulo,CTR MICROSCOPIA ELETR,São Paulo,BRAZILUniversidade Federal de São Paulo,CTR MICROSCOPIA ELETR,São Paulo,BRAZILWeb of Scienc

Transcription rate modulation through the Trypanosoma cruzi life cycle occurs in parallel with changes in nuclear organisation

In trypanosomes transcription occurs as large polycistronic units, with trans-splicing and polyadenylation generating each individual mRNA. There are no defined RNA. polymerase II promoters and mRNA stabilisation is most likely the process controlling levels of differentially expressed mRNAs, since no selective modulation of gene activity has even been reported at the transcriptional level. Here, we show a large decrease in the transcription rates by RNA polymerases I and II when proliferative forms of Trypanosoma cruzi (epimastigotes and amastigotes) transform into non-proliferative and infective forms (trypomastigotes). We also show that these changes in transcription occur in parallel with modifications in the nuclear structure. While nuclei of proliferative forms are round, contain small amounts of peripheral heterochromatin and a large nucleolus, nuclei of trypomastigotes are elongated, the nucleolus disappears and the heterochromatin occupies most of the nuclear compartment. the decrease in the transcription parallels the nucleolus disassembly, as seen by the dispersion of nucleolar antigens. As T. cruzi cycles continuously through proliferative and infective forms, the molecular mechanisms involved in the control of nuclear organisation and chromatin remodelling can be revealed by this system. (C) 2001 Elsevier Science B.V. All rights reserved.Universidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Microscopia Eletron, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Microscopia Eletron, BR-04023062 São Paulo, BrazilWeb of Scienc

A possible advantage of displaying the tail: a comparison between the tail and body integument structure in Amphisbaena alba and Leposternon microcephalum (Squamata, Amphisbaenia)

Amphisbaena alba when in a defensive position adopts a horseshoe posture, raises its head and tail and opens its mouth. the tail is rigid; the dorsal surface often has non-pigmented areas which resemble scars. Leposternon microcephalum lives sympatrically with A. alba; it has a soft tail which does not appear to be involved in defensive display. Both species have been observed in captivity. the height to which A. alba raises head and tail during defensive display was measured. Morphometrics and morphology of the integument structure in both species were studied in the body and in the tail from the collagen bundles organization viewpoint. the results reveal a mechanical resistance of the tail in A. alba, but not in L. microcephalum. It is possible that this structure, formed of a dense piece of collagen, serves as a 'biting block'; lesions caused by potential predators could cause no great harm. the skin of the remainder of the body in A. alba (but not in L. microcephalum) is also very resistant; the animal is practically covered by a flexible armour. (C) Elsevier, Paris.Inst Butantan, Cellular Biol Lab, BR-05503900 São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Electron Microscopy, São Paulo, BrazilUniv São Paulo, Fac Med, Lab Cellular Biol, São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Electron Microscopy, São Paulo, BrazilWeb of Scienc

Murine macrophages cultured with IL-4 acquire a phenotype similar to that of epithelioid cells from granulomatous inflammation

Epithelioid cells (ECs) found in granulomas are thought to derive from mononuclear phagocytes. Although GM-CSF and/or IL-4 are known to promote cell differentiation their role in the development of ECs has never been demonstrated. Here we showed that mouse macrophages treated exclusively with recombinant IL-4 (rIL-4) differentiate into epithelioid-like cells. Macrophages cultivated with rIL-4 presented a fried-egg shape, and ultrastructural studies revealed membrane interdigitations, cytoplasmic vesicles, prominent Golgi complex, and rough endoplasmic reticulum. Compared with controls, rIL-4 treated cells displayed increased expression of MHC class II molecules and of Migration Inhibitory Factor-Related Protein-14. Whereas mannose receptor-mediated phagocytosis was increased, Fcgamma-receptor mediated phagocytosis and the production of nitric oxide were decreased in treated cultures. All these features overlap those reported for ECs from granulomatous lesions. in conclusion, treatment of mouse peritoneal macrophages with rIL-4 drives their in vitro differentiation to an epithelioid phenotype and provides a tool to investigate the biology of ECs.Universidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Electron Microscopy, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Electron Microscopy, BR-04023900 São Paulo, BrazilWeb of Scienc