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991.
da Costa da Santos EK Honda RT Nozawa SR Ferreira-Nozawa MS 《Genetics and molecular biology》2012,35(1):134-141
Analysis of bacterial diversity in soils along the banks of the Solimões and
Negro rivers, state of Amazonas, Brazil, was by partial sequencing of the genes codifying
the rDNA16S region. Diversity of operational taxonomic units (OTU) and of the divergent
sequences obtained were applied in comparative analysis of microbiological diversity in
the two environments, based on richness estimators and OTU diversity indices. The higher
OTU diversity in the Solimões was based on the higher number of parameters that
evoke this. The interaction between the nucleotide sequences of bacteria inhabiting the
two riverine environments indicated that the two microrganism communities are similar in
composition. 相似文献
992.
Jorge Parodi Lenin Ochoa-de la Paz Ricardo Miledi Ataúlfo Martínez-Torres 《Molecules and cells》2012,34(4):349-355
Xenopus laevis oocytes exposed to amyloid-β aggregate generated oscillatory electric activity (blips) that was recorded by two-microelectrode voltage-clamp. The cells exhibited a series of “spontaneous” blips ranging in amplitude from 3.8 ± 0.9 nA at the beginning of the recordings to 6.8 ± 1.7 nA after 15 min of exposure to 1 μM aggregate. These blips were similar in amplitude to those induced by the channel-forming antimicrobial agents amphotericin B (7.8 ± 1.2 nA) and gramicidin (6.3 ± 1.1 nA). The amyloid aggregate-induced currents were abolished when extracellular Ca2+ was removed from the bathing solution, suggesting a central role for this cation in generating the spontaneous electric activity. The amyloid aggregate also affected the Ca2+-dependent Cl− currents of oocytes, as shown by increased amplitude of the transient-outward chloride current (Tout) and the serum-activated, oscillatory Cl− currents. Electron microcopy revealed that amyloid aggregate induced the dissociation of the follicular cells that surround the oocyte, thus leading to a failure in the electro-chemical communication between these cells. This was also evidenced by the suppression of the oscillatory Ca2+-dependent ATP-currents, which require proper coupling between oocytes and the follicular cell layer. These observations, made using the X. laevis oocytes as a versatile experimental model, may help to understand the effects of amyloid aggregate on cellular communication. 相似文献
993.
Root system architecture depends on nutrient availability, which shapes primary and lateral root development in a nutrient-specific manner. To better understand how nutrient signals are integrated into root developmental programs, we investigated the morphological response of Arabidopsis thaliana roots to iron (Fe). Relative to a homogeneous supply, localized Fe supply in horizontally separated agar plates doubled lateral root length without having a differential effect on lateral root number. In the Fe uptake-defective mutant iron-regulated transporter1 (irt1), lateral root development was severely repressed, but a requirement for IRT1 could be circumvented by Fe application to shoots, indicating that symplastic Fe triggered the local elongation of lateral roots. The Fe-stimulated emergence of lateral root primordia and root cell elongation depended on the rootward auxin stream and was accompanied by a higher activity of the auxin reporter DR5-β-glucuronidase in lateral root apices. A crucial role of the auxin transporter AUXIN RESISTANT1 (AUX1) in Fe-triggered lateral root elongation was indicated by Fe-responsive AUX1 promoter activities in lateral root apices and by the failure of the aux1-T mutant to elongate lateral roots into Fe-enriched agar patches. We conclude that a local symplastic Fe gradient in lateral roots upregulates AUX1 to accumulate auxin in lateral root apices as a prerequisite for lateral root elongation. 相似文献
994.
García-Bermúdez M López-Mejías R González-Juanatey C Castañeda S Miranda-Filloy JA Blanco R Fernández-Gutiérrez B Balsa A González-Alvaro I Gómez-Vaquero C Llorca J Martín J González-Gay MA 《DNA and cell biology》2012,31(7):1214-1220
Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with increased cardiovascular (CV) mortality. Toll-like receptor-4 (TLR4) activates the innate immune response via NF-kB pathway and mitogen-activated protein kinase signaling, leading to expression of proinflammatory cytokines and chemokines. The G allele of TLR4 rs4986790 (+896A>G, Asp299Gly) gene polymorphism has been implicated in reduction of risk of atherosclerosis. In this study, 1481 RA patients fulfilling the 1987 American College of Rheumatology (ACR) criteria were genotyped for the rs4986790 TLR4 variant to determine the influence of this variant in the risk of CV events in these patients. Also, HLA-DRB1 status was determined using molecular based methods. Moreover, potential influence of rs4986790 variant in the development of subclinical atherosclerosis was assessed in a subgroup of RA patients with no history of CV events by the measurement of surrogate markers of subclinical atherosclerosis. No statistically significant differences in allele or genotype frequencies for the rs4986790 variant between RA patients who experienced CV events or not were found. Likewise, no significant association between this gene variant and any of the surrogate markers of subclinical atherosclerosis was found. In summary, results in our study do not support the hypothesis that the rs4986790 (+896A>G, Asp299Gly) TLR4 variant may influence predisposition for subclinical atherosclerosis and clinically evident CV disease in RA patients. 相似文献
995.
Francisco J. Román‐Dañobeytia Samuel I. Levy‐Tacher James Aronson Ricardo Ribeiro Rodrigues Jorge Castellanos‐Albores 《Restoration Ecology》2012,20(3):378-386
The rainforest of Mexico has been degraded and severely fragmented, and urgently require restoration. However, the practice of restoration has been limited by the lack of species‐specific data on survival and growth responses to local environmental variation. This study explores the differential performance of 14 wet tropical early‐, mid‐ or late‐successional tree species that were grown in two abandoned pastures with contrasting land‐use histories. After 18 months, seedling survival and growth of at least 7 of the 14 tree species studied were significantly higher in the site with a much longer history of land use (site 2). Saplings of the three early‐successional species showed exceptional growth rates. However, differences in performance were noted in relation to the differential soil properties between the experimental sites. Mid‐successional species generally showed slow growth rates but high seedling survival, whereas late‐successional species exhibited poor seedling survival at both the study sites. Stepwise linear regressions revealed that the species integrated response index combining survivorship and growth measurements, was influenced mostly by differences in soil pH between the two abandoned pastures. Our results suggest that local environmental variation among abandoned pastures of contrasting land‐use histories influences sapling survival and growth. Furthermore, the similarity of responses among species with the same successional status allowed us to make some preliminary site and species‐specific silvicultural recommendations. Future field experiments should extend the number of species and the range of environmental conditions to identify site “generalists” or more narrowly adapted species, that we would call “sensitive.” 相似文献
996.
997.
Alicia Santos Savio Osvaldo Reyes Acosta Haydee Gerónimo Pérez Yunier Rodríguez Álvarez Araceli Chico Hilda Garay Pérez Miriam Ojeda Ojeda Celia Aurora Arrieta Aguero Miguel Estévez Gerardo Guillen Nieto 《Journal of peptide science》2012,18(1):25-29
IL‐15 is a proinflammatory cytokine that acts early in the inflammatory response and has been associated with several autoimmune diseases including rheumatoid arthritis, where it had been proposed as a therapeutic target. We recently reported an IL‐15 antagonist peptide corresponding to sequence 36–45 of IL‐15 (KVTAMKCFLL) named P8, which specifically binds to IL‐15Rα and inhibits IL‐15 biological activity with a half maximal inhibitory concentration (IC50) of 130 µ m in CTLL‐2 proliferation assay. In order to improve binding of peptide P8 to the receptor IL‐15Rα, we used an Ala scan strategy to study contribution of each individual amino acid to the peptide's antagonist effect. Here, we found that Phe and Cys are important for peptide binding to IL‐15Rα. We also investigated other single site mutations and replaced the second Lys in the sequence by the polar non‐charged amino acid threonine. The resulting peptide [K6T]P8 exhibited a higher activity than P8 with an IC50 of 24 µm . We also found that this peptide was more active than peptide P8 in the inhibition of TNFα secretion by synovial cells from rheumatoid arthritis patients. The peptide [K6T]P8 described in this work is a new type of IL‐15 antagonist and constitutes a potential therapeutic agent for rheumatoid arthritis. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
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