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41.
Aresta-Branco F Cordeiro AM Marinho HS Cyrne L Antunes F de Almeida RF 《The Journal of biological chemistry》2011,286(7):5043-5054
The plasma membrane of Saccharomyces cerevisiae was studied using the probes trans-parinaric acid and diphenylhexatriene. Diphenylhexatriene anisotropy is a good reporter of global membrane order. The fluorescence lifetimes of trans-parinaric acid are particularly sensitive to the presence and nature of ordered domains, but thus far they have not been measured in yeast cells. A long lifetime typical of the gel phase (>30 ns) was found in wild-type (WT) cells from two different genetic backgrounds, at 24 and 30 °C, providing the first direct evidence for the presence of gel domains in living cells. To understand their nature and location, the study of WT cells was extended to spheroplasts, the isolated plasma membrane, and liposomes from total lipid and plasma membrane lipid extracts (with or without ergosterol extraction by cyclodextrin). It is concluded that the plasma membrane is mostly constituted by ordered domains and that the gel domains found in living cells are predominantly at the plasma membrane and are formed by lipids. To understand their composition, strains with mutations in sphingolipid and ergosterol metabolism and in the glycosylphosphatidylinositol anchor remodeling pathway were also studied. The results strongly indicate that the gel domains are not ergosterol-enriched lipid rafts; they are mainly composed of sphingolipids, possibly inositol phosphorylceramide, and contain glycosylphosphatidylinositol-anchored proteins, suggesting an important role in membrane traffic and signaling, and interactions with the cell wall. The abundance of the sphingolipid-enriched gel domains was inversely related to the cellular membrane system global order, suggesting their involvement in the regulation of membrane properties. 相似文献
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Susana Cardoso Cristina Carvalho Ricardo Marinho Anabel Simões Cristina M. Sena Paulo Matafome Maria S. Santos Raquel M. Seiça Paula I. Moreira 《Journal of bioenergetics and biomembranes》2014,46(5):347-355
Advanced glycation end products (AGEs) and methylglyoxal (MG), an important intermediate in AGEs synthesis, are thought to contribute to protein aging and to the pathogenesis of age-and diabetes-associated complications. This study was intended to investigate brain mitochondria bioenergetics and oxidative status of rats previously exposed to chronic treatment with MG and/or with pyridoxamine (PM), a glycation inhibitor. Brain mitochondrial fractions were obtained and several parameters were analyzed: respiratory chain [states 3 and 4 of respiration, respiratory control ratio (RCR), and ADP/O index] and phosphorylation system [transmembrane potential (ΔΨm), ADP-induced depolarization, repolarization lag phase, and ATP levels]; hydrogen peroxide (H2O2) production levels, mitochondrial aconitase activity, and malondialdehyde levels as well as non-enzymatic antioxidant defenses (vitamin E and glutathione levels) and enzymatic antioxidant defenses (glutathione disulfide reductase (GR), glutathione peroxidase (GPx), and manganese superoxide dismutase (MnSOD) activities). MG treatment induced a statistical significant decrease in RCR, aconitase and GR activities, and an increase in H2O2 production levels. The administration of PM did not counteract MG-induced effects and caused a significant decrease in ΔΨm. In mitochondria from control animals, PM caused an adaptive mechanism characterized by a decrease in aconitase and GR activities as well as an increase in both α-tocopherol levels and GPx and MnSOD activities. Altogether our results show that high levels of MG promote brain mitochondrial impairment and PM is not able to reverse MG-induced effects. 相似文献
44.
R. C. Marinho C. Mendes‐Rodrigues A. M. Bonetti P. E. Oliveira 《Plant biology (Stuttgart, Germany)》2014,16(2):508-511
Approximately 70% of the angiosperm species are polyploid, an important phenomenon in the evolution of those plants. But ploidy estimates have often been hindered because of the small size and large number of chromosomes in many tropical groups. Since polyploidy affects cell size, morphometric analyses of pollen grains and stomata have been used to infer ploidy level. Polyploidy is present in many species of the Cerrado, the Neotropical savanna region in Central Brazil, and has been linked to apomixis in some taxa. Eriotheca gracilipes and Eriotheca pubescens are common tree species in this region, and present cytotypes that form reproductive mosaics. Hexaploid individuals (2n = 6x = 276) are polyembryonic and apomictic, while tetraploid and diploid individuals (2n = 2x = 92, 2n = 4x = 184) are sexual and monoembryonic. We tested whether morphometric analysis can be used to estimate ploidy levels in E. gracilipes and E. pubescens individuals. Pollen material from diploid and hexaploid individuals of E. gracilipes, and tetraploid and hexaploid individuals of E. pubescens, were fixed in 50% FAA, and expanded leaves were dried in silica gel. Pollen grains and stomata of at least five individuals from each population were measured. The results demonstrate that all measures were significantly different among cytotypes. Individuals with higher levels of ploidy (hexaploid) all presented measurements that were higher than those with lower levels (diploid and tetraploid). There was no overlap between ploidy levels in each species at 95% confidence interval. Thus, the size of the pollen grains and stomata are effective parameters for analysis of ploidy levels in E. gracilipes and E. pubescens. 相似文献
45.
Cintia Ferreira Marinho Elzinandes Leal Azeredo Amanda Torrentes-Carvalho Alessandro Marins-Dos-Santos Claire Fernandes Kubelka Luiz José de Souza Rivaldo Venancio Cunha Luzia Maria de-Oliveira-Pinto 《PloS one》2014,9(7)
In dengue virus (DENV) infection, complement system (CS) activation appears to have protective and pathogenic effects. In severe dengue fever (DF), the levels of DENV non-structural-1 protein and of the products of complement activation, including C3a, C5a and SC5b-9, are higher before vascular leakage occurs, supporting the hypothesis that complement activation contributes to unfavourable outcomes. The clinical manifestations of DF range from asymptomatic to severe and even fatal. Here, we aimed to characterise CS by their receptors or activation product, in vivo in DF patients and in vitro by DENV-2 stimulation on monocytes. In comparison with healthy controls, DF patients showed lower expression of CR3 (CD11b), CR4 (CD11c) and, CD59 on monocytes. The DF patients who were high producers of SC5b-9 were also those that showed more pronounced bleeding or vascular leakage. Those findings encouraged us to investigate the role of CS in vitro, using monocytes isolated from healthy subjects. Prior blocking with CR3 alone (CD11b) or CR3 (CD11b/CD18) reduced viral infection, as quantified by the levels of intracellular viral antigen expression and soluble DENV non-structural viral protein. However, we found that CR3 alone (CD11b) or CR3 (CD11b/CD18) blocking did not influence major histocompatibility complex presentation neither active caspase-1 on monocytes, thus probably ruling out inflammasome-related mechanisms. Although it did impair the secretion of tumour necrosis factor alpha and interferon alpha. Our data provide strategies of blocking CR3 (CD11b) pathways could have implications for the treatment of viral infection by antiviral-related mechanisms. 相似文献
46.
Camila Simioni Vanzin Vanusa Manfredini Ana Eveline Marinho Giovana Brondani Biancini Graziela Schmitt Ribas Marion Deon Angela Terezinha de Souza Wyse Moacir Wajner Carmen Regla Vargas 《Gene》2014
High blood levels of homocysteine (Hcy) are found in patients affected by homocystinuria, a genetic disorder caused by deficiency of cystathionine β-synthase (CBS) activity, as well as in nutritional deficiencies (vitamin B12 or folate) and in abnormal renal function. We previously demonstrated that lipid and protein oxidative damage is increased and the antioxidant defenses diminished in plasma of CBS-deficient patients, indicating that oxidative stress is involved in the pathophysiology of this disease. In the present work, we extended these investigations by evaluating DNA damage through the comet assay in peripheral leukocytes from CBS-deficient patients, as well as by analyzing of the in vitro effect of Hcy on DNA damage in white blood cells. We verified that DNA damage was significantly higher in the CBS-deficient patients under treatment based on a protein-restricted diet and pyridoxine, folic acid, betaine and vitamin B12 supplementation, when compared to controls. Furthermore, the in vitro study showed a concentration-dependent effect of Hcy inducing DNA damage. Taken together, the present data indicate that DNA damage occurs in treated CBS-deficient patients, possibly due to high Hcy levels. 相似文献
47.
PAULO M. FARIA E SILVA ANTONIO M. SOLÉ-CAVA MAURILIO J. SOARES MARIA CRISTINA M. MOTTA JOÁTO E. FIORINI WANDERLEY DE SOUZA 《The Journal of eukaryotic microbiology》1991,38(5):489-494
The trypanosomatid previously described as Crithidia roitmani is characterized here at the ultrastructural and biochemical levels. The data indicates that the parasite belongs to the Herpetomonas genus, and we therefore suggest the flagellate to be denominated as Herpetomonas roitmani n. comb. Cladistic analysis of isoenzyme data generated by eight different enzymes showed that the parasite presented a distinct banding pattern and could be grouped with some Herpetomonas spp., but not with Crithidia spp., used as reference strains. Accordingly, when the parasites were grown for longer periods in Roitman's defined medium, expontaneous differentiation from promastigotes to opisthomastigotes (typical of the Herpetomonas genus) occurred. Transmission electron microscopy revealed the presence of bacterium-like endosymbionts in the cytoplasm of all evolutive forms of the parasite. All morphological alterations characteristic of endosymbiont-bearing trypanosomatids could be observed. 相似文献
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Priscila Dallé da Rosa Claudete Locatelli Karla Scheid Diane Marinho Lúcia Kliemann Alexandre Fuentefria Luciano Zubaran Goldani 《Mycopathologia》2018,183(3):565-571
Lasiodiplodia theobromae is a rare ocular pathogen. We report a patient with fungal keratitis caused by L. theobromae. The patient was a 75-year-old male, a farmer with diabetes type II, and no previous history of ocular trauma. Histopathology analysis revealed the presence fungi invading Descemet’s membrane of the cornea. The fungus was characterized by septate, highly bulged fungal filaments involving full corneal thickness in the corresponding histopathology specimens. A dematiaceous mold was isolated and initally identified as L. theobromae by microscopic and macroscopic morphology, and further confirmed by PCR-based determination of internal transcribed spacer (ITS) regions of ribosomal DNA. Antifungal susceptibility tests showed sensitivity to amphotericin B (AMB) and voriconazole ( VRC), and resistance to other azoles, including itraconazole (ITC) and fluconazole (FLC). Corneal transplant was performed. Despite in vitro itraconazole resistance, the patient was successfully treated with oral itraconazole, topical voriconazole and natamycin, combined with ocular injections of amphotericin B and voriconazole. 相似文献
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