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391.
392.
Response surface methodology (RSM) was used to study the effect of three factors, sulfur dioxide, ethanol and glucose, on the growth of wine spoilage yeast species, Zygosaccharomyces bailii, Schizosaccharomyces pombe, Saccharomycodes ludwigii and Saccharomyces cerevisiae. Seventeen central composite rotatable design (CCRD) trials were designed for each test yeast using realistic concentrations of the factors (variables) in premium red wine. Polynomial regression equations were fitted to experimental data points, and the growth inhibitory conditions of these three variables were determined. The overall results showed Sa. ludwigii as the most resistant species growing under high ethanol/free sulfur dioxide concentrations, i.e., 15% (v/v)/20 mg L-1, 14% (v/v)/32 mg L-1 and 12.5% (v/v)/40 mg L-1, whereas other yeasts did not survive under the same levels of ethanol/free sulfur dioxide concentrations. The inhibitory effect of ethanol was primarily observed during longer incubation periods, compared with sulfur dioxide, which showed an immediate effect. In some CCRD trials, Sa. ludwigii and S. cerevisiae showed growth recovery after a short death period under the exposure of 20–32 mg L-1 sulfur dioxide in the presence of 11% (v/v) or more ethanol. However, Sc. pombe and Z. bailii did not show such growth recovery under similar conditions. Up to 10 g L-1 of glucose did not prevent cell death under the sulfur dioxide or ethanol stress. This observation demonstrates that the sugar levels commonly used in wine to sweeten the mouthfeel do not increase wine susceptibility to spoilage yeasts, contrary to the anecdotal evidence. 相似文献
393.
Suzana Markolovic Sarah E. Wilkins Christopher J. Schofield 《The Journal of biological chemistry》2015,290(34):20712-20722
The post-translational hydroxylation of prolyl and lysyl residues, as catalyzed by 2-oxoglutarate (2OG)-dependent oxygenases, was first identified in collagen biosynthesis. 2OG oxygenases also catalyze prolyl and asparaginyl hydroxylation of the hypoxia-inducible factors that play important roles in the adaptive response to hypoxia. Subsequently, they have been shown to catalyze N-demethylation (via hydroxylation) of Nϵ-methylated histone lysyl residues, as well as hydroxylation of multiple other residues. Recent work has identified roles for 2OG oxygenases in the modification of translation-associated proteins, which in some cases appears to be conserved from microorganisms through to humans. Here we give an overview of protein hydroxylation catalyzed by 2OG oxygenases, focusing on recent discoveries. 相似文献
394.
Roger Magno Macedo-Silva Carina de Lima Pereira dos Santos Vanessa Alvaro Diniz Jorge José de Carvalho Camila Guerra Suzana C?rte-Real 《Memórias do Instituto Oswaldo Cruz》2014,109(1):61-69
Fibrocytes are important for understanding the progression of many diseases because
they are present in areas where pathogenic lesions are generated. However, the
morphology of fibrocytes and their interactions with parasites are poorly understood.
In this study, we examined the morphology of peripheral blood fibrocytes and their
interactions with Leishmania (L.) amazonensis . Through
ultrastructural analysis, we describe the details of fibrocyte morphology and how
fibrocytes rapidly internalise Leishmania promastigotes. The
parasites differentiated into amastigotes after 2 h in phagolysosomes and the
infection was completely resolved after 72 h. Early in the infection, we found
increased nitric oxide production and large lysosomes with electron-dense material.
These factors may regulate the proliferation and death of the parasites. Because
fibrocytes are present at the infection site and are directly involved in developing
cutaneous leishmaniasis, they are targets for effective, non-toxic cell-based
therapies that control and treat leishmaniasis. 相似文献
395.
Renata C Hespanhol Maria de Nazaré C Soeiro Marcos B Meuser Maria de Nazareth S L Meirelles Suzana C?rte-Real 《The journal of histochemistry and cytochemistry》2005,53(1):35-44
Leishmania are protozoa that invade mononuclear phagocytes with the involvement of different ligand-receptor systems, including mannose receptors. Until now, scant data are available concerning the mechanisms that govern the infection of Leishmania in other host cell types such as fibroblasts. Our aim was to analyze the expression of mannose receptors in primary cultures of skin fibroblasts (SF) further characterizing their role during the invasion of promastigotes of Leishmania (L.) amazonensis. Both fluorescent, light, and electron microscopy assays revealed that SF have mannose receptors since they bound and internalized mannosylated ligands in addition to being positively labeled by fuc-BSA-FITC probes. d-mannose competition assays revealed the participation of mannose receptors during the parasite association with SF presenting upregulated receptor expression during the initial steps of the infection. After longer periods of Leishmania:fibroblasts contact, the modulation noted in the host mannose receptors was reverted concomitantly to the infection control, suggesting that the parasites were required for the alteration maintenance and providing evidences that the SF may display microbicidal mechanisms to control the Leishmania infection. 相似文献
396.
Daptomycin is a cyclic anionic lipopeptide that exerts its rapid bactericidal effect by perturbing the bacterial cell membrane, a mode of action different from most other currently commercially available antibiotics (except e.g. polymyxin and gramicidin). Recent work has shown that daptomycin requires calcium in the form of Ca2+ to form a micellar structure in solution and to bind to bacterial model membranes. This evidence sheds light on the initial steps in the mechanism of action of this novel antibiotic. To understand how daptomycin goes on to perturb bacterial membranes, its three-dimensional structure has been determined in the presence of 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) micelles. NMR spectra of daptomycin in DHPC were obtained under two conditions, namely in the presence of Ca2+ as used by Jung et al. [D. Jung, A. Rozek, M. Okon, R.E.W. Hancock, Structural transitions as determinants of the action of the calcium-dependent antibiotic daptomycin, Chem. Biol. 11 (2004) 949-57] to solve the calcium-conjugated structure of daptomycin in solution and in a phosphate buffer as used by Rotondi and Gierasch [K.S. Rotondi, L.M. Gierasch, A well-defined amphipathic conformation for the calcium-free cyclic lipopeptide antibiotic, daptomycin, in aqueous solution, Biopolymers 80 (2005) 374-85] to solve the structure of apo-daptomycin. The structures were calculated using molecular dynamics time-averaged refinement. The different sample conditions used to obtain the NMR spectra are discussed in light of fluorescence data, lipid flip-flop and calcein release assays in PC liposomes, in the presence and absence of Ca2+ [D. Jung, A. Rozek, M. Okon, R.E.W. Hancock, Structural transitions as determinants of the action of the calcium-dependent antibiotic daptomycin, Chem. Biol. 11 (2004) 949-57]. The implications of these results for the membrane perturbation mechanism of daptomycin are discussed. 相似文献
397.
Álan Panatta Cristina Stenert Suzana Maria Fagondes de Freitas Leonardo Maltchik 《Limnology》2006,7(1):23-30
The Chironomidae of tropical South America are a very rich species, but are scarcely known. The range of environmental conditions
under which chironomids are found is more extensive than that of any other group of aquatic insects. The objectives of this
study were to carry out a diversity survey of chironomid larvae in wetland systems of the coastal plain in the south of Brazil
and to analyze the effects of area, altitude, water conductivity, nitrate and phosphorus concentrations, and the life form
of the dominant plant species on chironomid richness and composition. Collections were carried out from March to April in
2002. A total of 30 taxa (23 morphospecies and 7 species) distributed along 23 genera were found, and the Chironominae showed
the greatest richness, followed by Tanypodinae and Orthocladiinae. The chironomid richness was higher in the emergent than
in the multistratified wetland class. The wetland area, altitude, nitrate and phosphorus concentrations, and water conductivity
did not influence the richness of Chironomidae. The Chironomidae genera and species were present in both the wetland classes
(emergent and aquatic bed vegetation). However, while Chironominae were more frequent in the emergent than in the aquatic
bed wetlands, no difference was observed for Tanypodinae. The aquatic vegetation was an important environmental predictor
for chironomid larvae richness in the studied wetlands in the south of Brazil. 相似文献
398.
Slobodan Jaric Suzana Blesic Sladjan Milanovic Sasa Radovanovic Milos Ljubisavljevic Radmila Anastasijevic 《European journal of applied physiology and occupational physiology》1999,80(5):467-471
We have tested the hypothesis that agonist and antagonist muscle fatigue could affect the final position of rapid, discrete movements. Six subjects performed consecutive elbow flexion and extension movements between two targets, with their eyes closed prior to, and after fatiguing the elbow extensor muscles. The results demonstrate that elbow extension movements performed in the post-test period systematically undershot the final position as compared to pre-test movements. However, attainment of the aimed final position in elbow flexion movements was unaffected by fatiguing of the extensor muscles. Undershoot of the final position obtained in extension movements was associated with agonist muscle fatigue, a result that was expected from the point of view of current motor control theories, and that could be explained by a reduced ability of the shortening muscle to exert force. On the other hand, the absence of the expected overshoot of the final position when the antagonist is fatigued, indicates the involvement of various reflex and/or central mechanisms operating around the stretched muscle that could contribute to returning the limb to the standard final position after a brief prominent overshoot. 相似文献
399.
Fábio Vieira dos Santos Vanessa Jaqueline da Silva Vieira dos Santos Maria José Farias Suzana de Fátima Paccola Mesquita Maria Aparecida Maciel Angelo da Cunha Pinto Ilce Mara de Syllos Cólus 《Biologia》2008,63(3):327-331
Croton cajucara Benth. (‘sacaca’) is a tree of the Euphorbiaceae family, native to the Amazon region in northern Brazil, where it is widely used in the popular
treatment of various diseases. Its active principle, the terpenoid trans-dehydrocrotonin, has been credited with a variety of medical properties, including antiulcer, antiinflammatory, antitumor,
antimutagenic and hypoglycemic activity. In this investigation, possible mutagenic and antimutagenic effects were evaluated
in treatments using methanol extract of this plant on Swiss Albino mice by examining their peripheral blood cells for micronuclei.
In these tests, the material obtained by methanol extraction of C. cajucara tree bark was administered to the mice by gavage. None of the doses evaluated in this study presented mutagenicity. Analysis
of the results obtained from studies evaluating antimutagenicity revealed protection against the chemotherapeutic agent cyclophosphamide
for the two highest doses used. 相似文献
400.
Suzana F. Dias L. Vilas-Boas J. M. S. Cabral M. M. R. Fonseca 《Biocatalysis and Biotransformation》1991,5(1):21-34
The enzymatic production of ethyl butyrate was studied: the lipase of Candida rugosa (E.C. 3.1.1.3.) was immobilized in a polyurethane matrix and subsequently introduced in an organic medium containing the substrates in appropriate concentrations. The large majority of experiments was carried out in n-hexane. Two further solvents were tested, namely n-heptane and n-dodecane. The partition coefficients matrix/solvent were estimated for the various solvent systems. The initial esterification rate, the molar yield ester/acid and the degree of conversion were found to be solvent independent when the reaction media were designed so that similar concentrations were created in the microenvironment. Initial rate experiments indicated that in n-hexane the threshold of inhibitory substrate concentrations lies (i) between 0.40 M and 0.50 M for butyric acid, according to the purity of the enzyme preparation and (ii) at 0.30 M for ethanol. Batch operational stability tests indicate that no enzyme deactivation occurs after 20 consecutive batches. 相似文献