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排序方式: 共有477条查询结果,搜索用时 46 毫秒
91.
André Luiz Rodrigues Roque Elisa Cupolillo Renato Sergio Marchevsky Ana Maria Jansen 《PLoS neglected tropical diseases》2010,4(2)
The importance of the genus Thrichomys in the retention of infection and transmission of Leishmania species is supported by previous studies that describe an ancient interaction between caviomorphs and trypanosomatids and report the natural infection of Thrichomys spp. Moreover, these rodents are widely dispersed in Brazil and recognized as important hosts of other tripanosomatids. Our main purpose was to evaluate the putative role of Thrichomys laurentius in the retention of infection and amplification of the transmission cycle of Leishmania infantum and L. braziliensis. Male and female T. laurentius (n = 24) born in captivity were evaluated for the retention of infection with these Leishmania species and followed up by parasitological, serological, hematological, biochemical, histological, and molecular assays for 3, 6, 9, or 12 months post infection (mpi). T. laurentius showed its competence as maintenance host for the two inoculated Leishmania species. Four aspects should be highlighted: (i) re-isolation of parasites 12 mpi; (ii) the low parasitic burden displayed by T. laurentius tissues; (iii) the early onset and maintenance of humoral response, and (iv) the similar pattern of infection by the two Leishmania species. Both Leishmania species demonstrated the ability to invade and maintain itself in viscera and skin of T. laurentius, and no rodent displayed any lesion, histological changes, or clinical evidence of infection. We also wish to point out the irrelevance of the adjective dermotropic or viscerotropic to qualify L. braziliensis and L. infantum, respectively, when these species are hosted by nonhuman hosts. Our data suggest that T. laurentius may act at least as a maintenance host of both tested Leishmania species since it maintained long-lasting infections. Moreover, it cannot be discarded that Leishmania spp. infection in free-ranging T. laurentius could result in higher parasite burden due the more stressing conditions in the wild. Therefore the tissular parasitism of the skin, infectiveness to the vector, and amplification of the transmission cycle of both Leishmania species could be expected. 相似文献
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The negative slope conductance created by the persistent sodium current (INaP) prolongs the decay phase of excitatory postsynaptic potentials (EPSPs). In a recent study, we demonstrated that this effect was due to an increase of the membrane time constant. When the negative slope conductance opposes completely the positive slope conductances of the other currents it creates a zero slope conductance region. In this region the membrane time constant is infinite and the decay phase of the EPSPs is virtually absent. Here we show that non-decaying EPSPs are present in CA1 hippocampal pyramidal cells in the zero slope conductance region, in the suprathreshold range of membrane potential. Na+ channel block with tetrodotoxin abolishes the non-decaying EPSPs. Interestingly, the non-decaying EPSPs are observed only in response to artificial excitatory postsynaptic currents (aEPSCs) of small amplitude, and not in response to aEPSCs of big amplitude. We also observed concomitantly delayed spikes with long latencies and high variability only in response to small amplitude aEPSCs. Our results showed that in CA1 pyramidal neurons INaP creates non-decaying EPSPs and delayed spikes in the subthreshold range of membrane potentials, which could potentiate synaptic integration of synaptic potentials coming from distal regions of the dendritic tree. 相似文献
94.
Summary Solid-state cultures of a pectinase-producing fungus (Aspergillus foetidus NRRL 341) were performed under different acidic conditions. Glass bottles containing 5 g of wheat bran and 7.5 mL of 0.2, 0.3, 0.4, or 0.5 N HCl were autoclaved (15 min, 121°C), inoculated with a spore suspension appropriately diluted to achieve an initial concentration of 4 × 104 spores per gram of wet substrate (with a 60 % humidity, on wet basis) and incubated at 30°C.Time course of pH and of different pectinase activities were determined in culture extracts. Total pectinase activity (TPA), expressed in terms of viscosimetric units per gram of wet substrate (VU.g–1), was affected by the initial culture acidity. The higher the HCl concentration used, the higher the TPA achieved, but after longer cultivation times. On the other hand, when 0.5 HCl was used, no fungal growth was observed. Nevertheless, enzyme productivity increased with culture acidity. When 0.4 HCl was used, TPA reached its maximum after 36 h of cultivation (2,535 VU.g–1). With 0.2 and 0.3 N HCl, TPA was the highest at 24 h (733 VU.g–1) and at 30 h (1,860 VU.g–1) respectively.The composition of the pectinase pool was also affected by culture acidity. The higher the acidity, the lower the pectinesterase activity and the higher both the polymethylgalacturonate lyase and polygalacturonase activities.Career Researchers from the Argentine National Research Council (CONICET). 相似文献
95.
The area between Ensenada and EI Rosario (Baja California, Mexico) has long been considered as a transitional zone in which two great ecoclimatic regions (Mediterranean and Tropical-Desert) overlap. The floristic and biotypical diversity of this area was evaluated by analyzing its shrubland formations from a phytosociological point of view. This phytosociological study, carried out according to the Braun-Blanquet method and supported by cluster analysis, describes sixteen shrubland associations from Northwestern Baja California.Floristic diversity of the transitional zone was evaluated using two indices, endemic value (EV) and endemic community value (ECV), which are related to the degree of endemism in the flora and plant associations. The phytosociological analysis showed that the high number of shrubland associations found in this area reflected its transitional character. The closer the associations are to the transitional zone, the higher their biotypical and floristic diversity.Abbreviations ADE
Adenostoma fasciculatum
- AES
Fraxinus trifoliata-Aesculus parryi
- BER
Bergerocactus emoryi-Agave shawii
- DES
Echinocereus engelmannii-Agave deserti
- ENC
Viguiera deltoidea-Encelia asperifolia
- EUR
Eurotia lanata-Yucca schidigera
- FOU
Agave cerulata-Fouquieria columnaris
- FRA
Atriplex julacea-Frankenia palmeri
- HYM
Baccharis glutinosa-Hymenoclea monogyra
- KEC
Clematis lasiantha-Keckiella antirrhinoides
- LAR
Ambrosia chenopodifolia-Larrea tridentata
- LYC
Ephedra californica-Lycium brevipes
- MAH
Malosma laurina-Heteromeles arbutifolia
- MUN
Salvia munzii-Artemisia californica
- ROS
Rosa minutifolia-Aesculus parryi
- SAL
Salvia apiana-Viguiera laciniata 相似文献
96.
Roque P. Almeida Anne Vanet Veronique Witko-Sarsat Maxine Melchior Denise McCabe Joelle E. Gabay 《Protein expression and purification》1996,7(4):355-366
The azurophil granules of human PMN contain four antibiotic proteins, the serprocidins, which have extensive homology to one another and to serine proteases. Azurocidin, a member of this family, is a 29-kDa glycoprotein with broad spectrum antimicrobial activity and chemotactic activity toward monocytes. Insect cells transfected with a baculovirus vector carrying azurocidin cDNA produced a recombinant azurocidin protein. We purified the recombinant azurocidin protein from the culture medium of the infected cells and showed that it retained the antimicrobial activity of the native neutrophil-derived molecule. In addition, we present evidence that a 49-amino-acid region of the recombinant azurocidin protein is required for its secretion from insect cells. 相似文献
97.
98.
99.
Identification of lysosomal Npc1‐binding proteins: Cathepsin D activity is regulated by NPC1
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Judit Macías‐Vidal Martina Guerrero‐Hernández Josep Maria Estanyol Carmen Aguado Erwin Knecht Oriol Bachs 《Proteomics》2016,16(1):150-158
Niemann–Pick type C (NPC) disease is an inherited lysosomal storage disorder, characterized by severe neurodegeneration. It is mostly produced by mutations in the NPC1 gene, encoding for a protein of the late endosomes/lysosomes membrane, involved in cholesterol metabolism. However, the specific role of this protein in NPC disease still remains unknown. We aimed to identify Npc1‐binding proteins in order to define new putative NPC1 lysosomal functions. By affinity chromatography using an Npc1 peptide (amino acids 1032–1066 of loop I), as bait, we fished 31 lysosomal proteins subsequently identified by LC‐MS/MS. Most of them were involved in proteolysis and lipid catabolism and included the protease cathepsin D. Cathepsin D and NPC1 interaction was validated by immunoprecipitation and the functional relevance of this interaction was studied. We found that fibroblasts from NPC patients with low levels of NPC1 protein have high amounts of procathepsin D but reduced quantities of the mature protein, thus showing a diminished cathepsin D activity. The increase of NPC1 protein levels in NPC cells by treatment with the proteasome inhibitor bortezomib, induced an elevation of cathepsin D activity. All these results suggest a new lysosomal function of NPC1 as a regulator of cathepsin D processing and activity. 相似文献
100.
Priscila L. dos Santos Fabrícia A. de Oliveira Micheli Luize B. Santos Luana Celina S. Cunha Michelle T. B. Lino Michelle F. S. de Oliveira Manuela O. M. Bomfim Angela Maria Silva Tatiana R. de Moura Amélia R. de Jesus Malcolm S. Duthie Steven G. Reed Roque P. de Almeida 《PLoS neglected tropical diseases》2016,10(1)