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991.
Rolando Carrisoza Carolina Salvador Norma A. Bobadilla Joyce Trujillo Laura I. Escobar 《Histochemistry and cell biology》2010,133(2):189-199
Potassium (K+) channels participate in K+ secretion, K+ recycling, and cell volume regulation and help to maintain the resting potential in mammalian kidneys. Previously, we identified
a set of voltage-gated K+ channels (Kv1) in the inner medullary collecting duct of the rat kidney. In the present work, we identified the voltage-gated
K+ channel ether-à-go-go-related gene (ERG) in the rat kidney. mRNAs of ERG1a and its N-terminal splice-variant ERG1b were detected. Immunoblots of the cortex and medulla revealed two molecular mass proteins of 135 and 80 kDa, consistent in
size with the nonglycosylated ERG1a and ERG1b isoforms, respectively. However, bands of 155 and 95 kDa, corresponding to mature
glycosylated ERG1a and ERG1b, respectively, were also observed. In our immunohistochemical experiments, we could not differentiate
the ERG1 isoforms because we used an antibody against a carboxy-terminal epitope. ERG1 was differentially localized in specific
nephron segments: its localization was intracellular in the proximal tubule and medullary collecting ducts and in the apical
membranes in the distal convoluted and connecting tubules. ERG1 was also abundant in glomerular arterioles and renal vessels.
In summary, ERG1 displays a heterogeneous distribution in the rat kidney. 相似文献
992.
Phosphoenolpyruvate (PEP) carboxykinases catalyse the reversible formation of oxaloacetate (OAA) and ATP (or GTP) from PEP, ADP (or GDP) and CO2. They are activated by Mn2+, a metal ion that coordinates to the protein through the ?-amino group of a lysine residue, the N?-2-imidazole of a histidine residue, and the carboxylate from an aspartic acid residue. Neutrality in the ?-amino group of Lys213 of Saccharomyces cerevisiae PEP carboxykinase is expected to be favoured by the vicinity of ionised Lys212. Glu272 and Glu284, located close to Lys212, should, in turn, electrostatically stabilise its positive charge and hence assist in keeping the ?-amino group of Lys213 in a neutral state. The mutations Glu272Gln, Glu284Gln, and Lys212Met increased the activation constant for Mn2+ in the main reaction of the enzyme up to seven-fold. The control mutation Lys213Gln increased this constant by ten-fold, as opposed to control mutation Lys212Arg, which did not affect the Mn2+ affinity of the enzyme. These observations indicate a role for Glu272, Glu284, and Lys212 in assisting Lys213 to properly bind Mn2+. In an unexpected result, the mutations Glu284Gln, Lys212Met and Lys213Gln changed the nucleotide-independent OAA decarboxylase activity of S. cerevisiae PEP carboxykinase into an ADP-requiring activity, implying an effect on the OAA binding characteristics of PEP carboxykinase. 相似文献
993.
Carolina Fortes Rigos Hérica de Lima Santos Juliana Sakamoto Yoneda Guillermo Montich Bruno Maggio Pietro Ciancaglini 《Biophysical chemistry》2010
We studied the thermal dependence of amide I′ infrared absorption and fluorescence emission of Trp residues in the Na,K-ATPase of rabbit kidney. We studied the whole enzyme solubilized with detergent, the whole enzyme reconstituted in proteoliposomes and the protein fraction that remained in the lipid membrane after the trypsin digestion of the proteoliposomes. Cooperative unfolding and aggregation with increasing temperature were observed in the whole protein, whether solubilized or reconstituted, but not in the fraction remaining after trypsinization. The protein influenced the physical state of the lipid, decreasing the temperature of the gel to liquid-crystalline phase transition and the degree of cooperativity. This study provides new information for the understanding of the processes controlling the association mechanisms that are important for enzyme function in natural membranes. 相似文献
994.
Neonatal hypoxia/ischemia (HI) is the most common cause of developmental neurological, cognitive and behavioral deficits in
children, with hyperoxia (HHI) treatment being a clinical therapy for newborn resuscitation. Although cerebral edema is a
common outcome after HI, the mechanisms leading to excessive fluid accumulation in the brain are poorly understood. Given
the rigid nature of the bone-encased brain matter, knowledge of edema formation in the brain as a consequence of any injury,
as well as the importance of water clearance mechanisms and water and ion homeostasis is important to our understanding of
its detrimental effects. Knowledge of the pathological process underlying the appearance of dysfunctional outcomes after development
of cerebral edema after neonatal HI in the developing brain and the molecular events triggered will allow a rational assessment
of HHI therapy for neonatal HI and determine whether this treatment is beneficial or harmful to the developing infant. 相似文献
995.
Noguti EN Leite CQ Malaspina AC Santos AC Hirata RD Hirata MH Mamizuka EM Cardoso RF 《Memórias do Instituto Oswaldo Cruz》2010,105(6):779-785
The purpose of this study was to provide information about the genetic diversity and prevalent genotype of Mycobacterium tuberculosis in a low-endemic setting in northwestern state of Paraná in Southern Brazil. We employed spoligotyping and mycobacterial interspersed repetitive units-variable number tandem repeat (MIRU-VNTR) techniques to genotype M. tuberculos isisolates from patients with pulmonary tuberculosis (TB). The 93 isolates analyzed by spoligotyping were divided into 36 different patterns, 30 of which were described in the SITVIT database. Latin American and Mediterranean, Haarlem and T families were responsible for 26.9%, 17.2% and 11.8% of TB cases, respectively. From the 84 isolates analyzed by MIRU-VNTR, 58 shared a unique pattern and the remaining 26 belonged to nine clusters. The MIRU loci 40, 23, 10 and 16 were the most discriminatory. A combination of MIRU-VNTR and spoligotyping resulted in 85.7% discriminatory power (Hunter-Gaston index = 0.995). Thus, combining spoligotyping and MIRU-VNTR typing proved to be most useful for epidemiological study in this low-endemic setting in Southern Brazil. The current study demonstrated that there is significant diversity in circulating strains in the city of Maringá and the surrounding regions, with no single genotype of M. tuberculosis predominating. 相似文献
996.
Staggemeier R Venker CA Klein DH Petry M Spilki FR Cantarelli VV 《Memórias do Instituto Oswaldo Cruz》2010,105(7):873-878
Bartonella spp are the causative agent of cat scratch disease in humans. Cats are the natural reservoir of these bacteria and may infect humans through scratches, bites or fleas. Blood samples from 47 cats aged up to 12 months were collected for this study. All animals were lodged in municipal animal shelters in the Vale do Sinos region, Rio Grande do Sul, Brazil. Bartonella spp were detected by genus-specific polymerase chain reaction (PCR) and when the PCR was positive, the species were determined by DNA sequencing. A Giemsa-stained blood smear was also examined for the presence of intraerythrocytic elements suggestive of Bartonella spp infection. Phylogenetic analysis was also performed for all positive samples. Using molecular detection methods, Bartonella spp were detected in 17.02% (8/47) of the samples. In seven out of eight samples confirmed to be positive for Bartonella spp, blood smear examination revealed the presence of intraerythrocytic elements suggestive of Bartonella spp. Phylogenetic analysis characterized positive samples as Bartonella henselae (5) or Bartonella clarridgeiae (3). To the best of our knowledge, this is the first molecular study demonstrating the presence of Bartonella spp in cats from the Southern Region of Brazil. 相似文献
997.
Topp S Reynoso CM Seeliger JC Goldlust IS Desai SK Murat D Shen A Puri AW Komeili A Bertozzi CR Scott JR Gallivan JP 《Applied and environmental microbiology》2010,76(23):7881-7884
We developed a series of ligand-inducible riboswitches that control gene expression in diverse species of Gram-negative and Gram-positive bacteria, including human pathogens that have few or no previously reported inducible expression systems. We anticipate that these riboswitches will be useful tools for genetic studies in a wide range of bacteria. 相似文献
998.
Luciano Neves de Medeiros Renata Angeli Carolina G. Sarzedas Ana Paula Valente Eleonora Kurtenbach 《生物化学与生物物理学报:生物膜》2010,1798(2):105-113
Plant defensins are cysteine-rich cationic peptides, components of the innate immune system. The antifungal sensitivity of certain exemplars was correlated to the level of complex glycosphingolipids in the membrane of fungi strains. Psd1 is a 46 amino acid residue defensin isolated from pea seeds which exhibit antifungal activity. Its structure is characterized by the so-called cysteine-stabilized α/β motif linked by three loops as determined by two-dimensional NMR. In the present work we explored the measurement of heteronuclear Nuclear Overhauser Effects, R1 and R2 15N relaxation ratios, and chemical shift to probe the backbone dynamics of Psd1 and its interaction with membrane mimetic systems with phosphatidylcholine (PC) or dodecylphosphocholine (DPC) with glucosylceramide (CMH) isolated from Fusarium solani. The calculated R2 values predicted a slow motion around the highly conserved among Gly12 residue and also in the region of the Turn3 His36-Trp38. The results showed that Psd1 interacts with vesicles of PC or PC:CMH in slightly different forms. The interaction was monitored by chemical shift perturbation and relaxation properties. Using this approach we could map the loops as the binding site of Psd1 with the membrane. The major binding epitope showed conformation exchange properties in the μs-ms timescale supporting the conformation selection as the binding mechanism. Moreover, the peptide corresponding to part of Loop1 (pepLoop1: Gly12 to Ser19) is also able to interact with DPC micelles acquiring a stable structure and in the presence of DPC:CMH the peptide changes to an extended conformation, exhibiting NOE mainly with the carbohydrate and ceramide parts of CMH. 相似文献
999.
Felipe A. Arenas Carolina A. Leal James A. Imlay 《Biochemical and biophysical research communications》2010,398(4):690-694
Most aerobic organisms are exposed to oxidative stress. Looking for enzyme activities involved in the bacterial response to this kind of stress, we focused on the btuE-encoded Escherichia coli BtuE, an enzyme that shares homology with the glutathione peroxidase (GPX) family. This work deals with the purification and characterization of the btuE gene product.Purified BtuE decomposes in vitro hydrogen peroxide in a glutathione-dependent manner. BtuE also utilizes preferentially thioredoxin A to decompose hydrogen peroxide as well as cumene-, tert-butyl-, and linoleic acid hydroperoxides, confirming that its active site confers non-specific peroxidase activity. These data suggest that the enzyme may have one or more organic hydroperoxide as its physiological substrate.The btuE gene was induced when cells were exposed to oxidative stress elicitors that included potassium tellurite, menadione and hydrogen peroxide, among others, suggesting that BtuE could participate in the E. coli response to reactive oxygen species. To our knowledge, this is the first report describing a glutathione peroxidase in E. coli. 相似文献
1000.
Carolina V. de Castilho William E. Magnusson R. Nazaré O. de Araújo Flávio J. Luizão 《Biotropica》2010,42(1):95-103
We monitored seventy-two 1 ha permanent plots spread over 64 km2 of terra firme forest at Reserva Ducke (Manaus, Amazonas, Brazil) over 2-yr intervals to assess the effects of a soil and topographic gradient on the rate of change in the aboveground tree live biomass (AGLB). AGLB increased significantly over the 2-yr intervals, exhibiting a mean rate of change of 1.65 Mg/ha/yr (bootstrapped 95% CI: 1.15, 2.79). The rate of change varied according to tree size class; understory and sub-canopy trees exhibited higher rates of change. Over the whole period, the rate of change was not related to soil or topographic features of the plots, but there was evidence that the relationships varied depending on the year of measurement. In the plots monitored between 2001 and 2003 we found a significant relationship between AGLB change and the soil textural gradient, but this relationship was not evident in plots monitored between 2002 and 2004. This suggests that both the temporal variation in the soil–biomass change relationship and the size structure of the forest need to be included in models of biomass change in Amazonia. We also noted that the rate of biomass change is sensitive to the equation used to estimate AGLB. Allometric models that incorporate wood-density data provide higher per plot AGLB estimates, but lower rates of change, suggesting that variations in floristic composition have important implications for carbon cycling in diverse tropical forests.
Abstract in Portuguese is available at http://www.blackwell-synergy.com/loi/btp . 相似文献
Abstract in Portuguese is available at http://www.blackwell-synergy.com/loi/btp . 相似文献