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141.
Fire is an important ecological factor that structures savannas, such as the cerrado, by selecting plant species and altering soil nutrient content. In Emas National Park, central Brazil, we compared soils under three different fire regimes and their relationship to the cerrado species they support. We collected 25 soil and vegetation samples at each site. We found differences in soil characteristics (p?<?0.05), with fertility and fire frequency positively related: in the annually burned site we found higher values of organic matter, nitrogen, and clay, whereas in the protected site we detected lower values of pH and higher values of aluminum. We also observed differences in plant community structure, with distinct floristic compositions in each site. Floristic composition was more related to sand proportion (intra-set correlation?=?0.834). Different fire frequencies increase environmental heterogeneity and beta diversity in the Brazilian cerrado. 相似文献
142.
Danilo G. Ceschin María C. Sánchez Gustavo A. Chiabrando 《Journal of cellular biochemistry》2009,106(3):372-380
Low‐density lipoprotein receptor‐related protein 1 (LRP1) is an endocytic receptor, which binds and internalizes diverse ligands such as activated α2‐macroglobulin (α2M*). LRP1 promotes intracellular signaling, which downstream mediates cellular proliferation and migration of different types of cells, including macrophages. Unlike the LDL receptor, LRP1 expression is not sensitive to cellular cholesterol levels but appears to be responsive to insulin. It has been previously demonstrated that insulin increases the cell surface presentation of LRP1 in adipocytes and hepatocytes, which is mediated by the intracellular PI3K/Akt signaling activation. The LRP1 protein distribution is similar to other insulin‐regulated cell surface proteins, including transferring receptor (Tfr). However, in macrophages, the insulin effect on the LRP1 distribution and expression is not well characterized. Considering that macrophages play a central role in the pathogenesis of atherosclerosis, herein we evaluate the effect of insulin on the cellular expression of LRP1 in J774 macrophages‐derived cells using Western blot and immunofluorescence microscopy. Our data demonstrate that insulin induces a significant decrease in the LRP1 protein content, without changing the specific mRNA level of this receptor. Moreover, insulin specifically affected the protein expression of LRP1 but not Tfr. The insulin‐induced protein degradation of LRP1 in J774 cells was mediated by the activation of the PI3K/Akt pathway and proteasomal system by an enhanced ubiquitin–receptor conjugation. The decreased content of LRP1 induced by insulin affected the cellular internalization of α2M*. Thus, we propose that the protein degradation of LRP‐1 induced by insulin in macrophages could have important effects on the pathogenesis of atherosclerosis. J. Cell. Biochem. 106: 372–380, 2009. © 2008 Wiley‐Liss, Inc. 相似文献
143.
Tiago F. Carrijo Divino Brandão Danilo E. de Oliveira Diogo A. Costa Thiago Santos 《Journal of Insect Conservation》2009,13(6):575-581
The advance of agricultural frontier may cause the Cerrado (Brazilian savanna) to disappear before 2030. This work focuses
on measuring the impact of pasture implantation on a cerrado’s termite fauna. Termites were sampled in a cerrado sensu stricto
and a pasture, originally cerrado. All species were classified as their feeder group, accumulation curves were made and Shannon-Wiener
indexes and β diversity were calculated for both areas. Cerrado was richer than pasture and species composition differed considerably,
leading β diversity to a high value. The humivorous was the most representative species, followed by grass/litter feeders, xylophagous
and, less representative, the intermediates. There were more xylophagous and intermediates species on cerrado than in pasture;
the grass/litter feeders were more abundant in pasture, but didn’t differed in number or species; and humivorous didn’t differed
neither in richness nor in abundance. This work shows that the simplification of the habitat is indeed causing the extinction
of populations that depend on some specifics resource. 相似文献
144.
D. Roman-Campos A.C. Campos C.R. Gioda P.P. Campos M.A.A. Medeiros J.S. Cruz 《Life sciences》2009,84(23-24):817-824
AimsThiamine is an important cofactor present in many biochemical reactions, and its deprivation can lead to heart dysfunction. Little is known about the influence of thiamine deprivation on the electrophysiological behavior of the isolated heart cells and information about thiamine deficiency in heart morphology is controversial. Thus, we decided to investigate the major repolarizing conductances and their influence in the action potential (AP) waveform as well as the changes in the heart structure in a set of thiamine deficiency in rats.Main methodsUsing the patch-clamp technique, we investigated inward (IK1) and outward K+ currents (Ito), T-type and L-type Ca2+ currents and APs. To evaluate heart morphology we used hematoxylin and eosin in transversal heart sections.Key findingsThiamine deficiency caused a marked decrease in left ventricle thickness, cardiomyocyte number, cell length and width, and membrane capacitance. When evaluating Ito we did not find difference in current amplitude; however an acceleration of Ito inactivation was observed. IK1 showed a reduction in the amplitude and slope conductance, which implicated a less negative resting membrane potential in cardiac myocytes isolated from thiamine-deficient rats. We did not find any difference in L-type Ca2+ current density. T-type Ca2+ current was not observed. In addition, we did not observe significant changes in AP repolarization.SignificanceBased on our study we can conclude that thiamine deficiency causes heart hypotrophy and not heart hypertrophy. Moreover, we provided evidence that there is no major electrical remodeling during thiamine deficiency, a feature of heart failure models. 相似文献
145.
Emanuela Giombini Massimiliano Orsini Danilo Carrabino Anna Tramontano 《BMC bioinformatics》2010,11(1):39
Background
Bacterial infections represent a global health challenge. The identification of novel antibacterial targets for both therapy and vaccination is needed on a constant basis because resistance continues to spread worldwide at an alarming rate. Even infections that were once easy to treat are becoming difficult or, in some cases, impossible to cure. Ideal targets for both therapy and vaccination are bacterial proteins exposed on the surface of the organism, which are often involved in host-pathogen interaction. Their identification can greatly benefit from technologies such as bioinformatics, proteomics and DNA microarrays. 相似文献146.
Ettmayer P Baumruker T Guerini D Mechtcheriakova D Nussbaumer P Streiff MB Billich A 《Bioorganic & medicinal chemistry letters》2006,16(1):84-87
Fluorescently labeled chiral analogs of the immunomodulatory drug FTY720 and its corresponding phosphates with variable aliphatic spacers between the aromatic ring and the NBD label have been synthesized. Determining the influence of the spacer on the in vitro phosphorylation rate by SPHK1 and 2 resulted in the identification of NBD-(R)-AAL 1c,d which are phosphorylated with an efficiency comparable to that of the unlabeled FTY720 analog (R)-AAL. Furthermore, the NBD-(R)-AAL phosphates 10c,d were proven to be a functional S1P receptor agonist. 相似文献
147.
Vaccine-induced cellular immune responses reduce plasma viral concentrations after repeated low-dose challenge with pathogenic simian immunodeficiency virus SIVmac239
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Wilson NA Reed J Napoe GS Piaskowski S Szymanski A Furlott J Gonzalez EJ Yant LJ Maness NJ May GE Soma T Reynolds MR Rakasz E Rudersdorf R McDermott AB O'Connor DH Friedrich TC Allison DB Patki A Picker LJ Burton DR Lin J Huang L Patel D Heindecker G Fan J Citron M Horton M Wang F Liang X Shiver JW Casimiro DR Watkins DI 《Journal of virology》2006,80(12):5875-5885
The goal of an AIDS vaccine regimen designed to induce cellular immune responses should be to reduce the viral set point and preserve memory CD4 lymphocytes. Here we investigated whether vaccine-induced cellular immunity in the absence of any Env-specific antibodies can control viral replication following multiple low-dose challenges with the highly pathogenic SIVmac239 isolate. Eight Mamu-A*01-positive Indian rhesus macaques were vaccinated with simian immunodeficiency virus (SIV) gag, tat, rev, and nef using a DNA prime-adenovirus boost strategy. Peak viremia (P = 0.007) and the chronic phase set point (P = 0.0192) were significantly decreased in the vaccinated cohort, out to 1 year postinfection. Loss of CD4(+) memory populations was also ameliorated in vaccinated animals. Interestingly, only one of the eight vaccinees developed Env-specific neutralizing antibodies after infection. The control observed was significantly improved over that observed in animals vaccinated with SIV gag only. Vaccine-induced cellular immune responses can, therefore, exert a measure of control over replication of the AIDS virus in the complete absence of neutralizing antibody and give us hope that a vaccine designed to induce cellular immune responses might control viral replication. 相似文献
148.
Calò L Cinque C Patanè M Schillaci D Battaglia G Melchiorri D Nicoletti F Bruno V 《Journal of neurochemistry》2006,98(1):1-10
There is increasing evidence that Eph receptors and their transmembrane ligands, named ephrins, interact with glutamate receptors in both developing and adult neurons. EphB receptors interact with proteins that regulate the membrane trafficking of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor subunits, and both ephrins and EphB receptors have been found to co-localize with N-methyl-d-aspartate (NMDA) receptors and to positively modulate NMDA receptor function. Moreover, pharmacologic activation of ephrin-Bs amplifies group-I metabotropic glutamate receptor signaling through mechanisms that involve NMDA receptors. The interaction with ionotropic or metabotropic glutamate receptors provides a substrate for the emerging role of ephrins and Eph receptors in the regulation of activity-dependent forms of synaptic plasticity, such as long-term potentiation and long-term depression, which are established electrophysiologic models of associative learning. In addition, these interactions explain the involvement of ephrins/Eph receptors in the regulation of pain threshold and epileptogenesis, as well as their potential implication in processes of neuronal degeneration. This may stimulate the search for new drugs that might modulate excitatory synaptic transmission by interacting with the ephrin/Eph receptor system. 相似文献
149.
Rocha DD Militão GC Veras ML Pessoa OD Silveira ER Alves AP de Moraes MO Pessoa C Costa-Lotufo LV 《Life sciences》2006,79(18):1692-1701
Withaphysalins are C(28)-steroidal lactones structurally based on the ergostane skeleton that possess antiproliferative activity against tumor cell lines. In the present study, the antileukemic actvity of withaphysalin O (1), M (2), and N (3) isolated from Acnistus arborescens, against two leukemic cell lines, HL-60 and K562, was evaluated, and the cytotoxicity compared with the effects on peripheral blood mononuclear cells (PBMC). All tested compounds reduced the number of viable cells of the tumor cell lines after 24 h of exposure, except for compound 2 against the K562 cell line. The reduction was time-and concentration-dependent, and the IC(50) values ranged from 0.7 to 3.5 microM after 72 h of incubation. In addition to the growth inhibitory properties, the drugs decreased DNA synthesis after 24 h of drug exposure evaluated by the 5-bromo-2 -deoxyuridine incorporation method. None of the tested compounds reduced the number of PBMC (IC(50)>20 microM) after 72 h of incubation, in contrast to doxorubicin that decreased viable cells and increased non-viable cells even after 24 h of incubation. Morphological analysis of treated cells using hematoxylin/eosin staining indicated the presence of necrotic cells for all tested compounds in HL-60, confirmed by the use of acridine orange/ethidium bromide staining. In addition to necrotic cells, K562 cells showed morphological alterations consistent with apoptosis. 相似文献
150.
Johan Lorenzen Sascha David Ferdinand H. Bahlmann Kirsten de Groot Elisabeth Bahlmann Jan T. Kielstein Hermann Haller Danilo Fliser 《PloS one》2010,5(7)