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991.
Artoni RF Vicari MR Endler AL Cavallaro ZI de Jesus CM de Almeida MC Moreira-Filho O Bertollo LA 《Genetica》2006,127(1-3):277-284
B chromosomes in Prochilodus lineatus, a migratory neotropical fish, were analyzed in a comparative study among populations from the Dourada lagoon (State of Paraná, Brazil) and from Mogi-Guaçu river (State of São Paulo, Brazil). The data on C-banding and fluorescent in situ hybridization with a satellite DNA probe (SATH1), indicate that the small metacentric B chromosome might correspond to an isochromosome. On the other hand, both populations presented a distinct set of B chromosomes, differentiated either by their number and by the presence of variant B types in the population from Mogi-Guaçu river. The present results indicate that the B chromosomes of P. lineatus should have an ancient origin, and have undergone a differential evolutionary pathway among distinct populations. 相似文献
992.
Costa-Neto CM Parreiras-E-Silva LT Ruller R Oliveira EB Miranda A Oliveira L Ward RJ 《Biochemical and biophysical research communications》2006,347(3):634-640
The eukaryotic translation initiation factor 5A (eIF5A) is a protein ubiquitously present in archaea and eukarya, which undergoes a unique two-step post-translational modification called hypusination. Several studies have shown that hypusination is essential for a variety of functional roles for eIF5A, including cell proliferation and synthesis of proteins involved in cell cycle control. Up to now neither a totally selective inhibitor of hypusination nor an inhibitor capable of directly binding to eIF5A has been reported in the literature. The discovery of such an inhibitor might be achieved by computer-aided drug design based on the 3D structure of the human eIF5A. In this study, we present a molecular model for the human eIF5A protein based on the crystal structure of the eIF5A from Leishmania brasiliensis, and compare the modeled conformation of the loop bearing the hypusination site with circular dichroism data obtained with a synthetic peptide of this loop. Furthermore, analysis of amino acid variability between different human eIF5A isoforms revealed peculiar structural characteristics that are of functional relevance. 相似文献
993.
Stifanese R Averna M Salamino F Cantoni C Mingari MC Prato C Pontremoli S Melloni E 《Archives of biochemistry and biophysics》2006,456(1):48-57
As previously suggested by PCR analysis [R. DeTullio, R. Stifanese, F. Salamino, S. Pontremoli, E. Melloni, Characterization of a new p94-like calpain form in human lymphocytes, Biochem. J. 375 (2003) 689-696], a p94-like calpain was now established to be present in six different human cells resembling the various peripheral blood cell types. This protease resulted to be the predominant calpain isoforms whereas the conventional mu- and m-calpains are also expressed although at lower or almost undetectable amounts. The p94-like calpain has been identified by a specific mAb and displays unique features such as: Ca2+ requirement for half maximum activity around 30 microM; no autolytic conversion to a low Ca2+ requiring form and lower sensitivity to calpastatin inhibition. Following cell stimulation, the p94-like calpain undergoes inactivation, a process indicating that the protease is activated and participates in the cell responses to stimuli. The involvement of this protease isoform in immunocompetent cell activation is further supported by its partial recruitment on plasma membranes, the site of action of the conventional calpain forms. The amount of calpain translocated to the membranes correlates to the level of calpastatin which has been shown to control this process through the formation of a complex with calpain, which maintains the protease in the cytosol. These results provide new information on the calpain/calpastatin system expressed in immunocompetent cells and on the functional relationship between the p94-like calpain and the biological function of these cells. 相似文献
994.
Alvarez I Bengochea M Toledo R Carretto E Hidalgo PC 《Human biology; an international record of research》2006,78(4):513-525
HLA class I antigens were determined for 959 unrelated Uruguayans. The predominant HLA alleles were A2, Cw4, and B35, and the most frequently observed two-loci haplotypes were A2-B44 and B35-Cw4. The most frequent three-loci HLA haplotype was A2-Cw5-B44. We compared the Uruguayan sample with similar data from other populations. 相似文献
995.
The Ena/VASP and WASP family of proteins play distinct roles in actin cytoskeleton remodeling. Ena/VASP is linked to actin filament elongation, whereas WASP plays a role in filament nucleation and branching mediated by Arp2/3 complex. The molecular mechanisms controlling both processes are only emerging. Both Ena/VASP and WASP are multidomain proteins. They both present poly-Pro regions, which mediate the binding of profilin-actin, followed by G-actin-binding (GAB) domains of the WASP-homology 2 (WH2) type. However, the WH2 of Ena/VASP is somewhat different from that of WASP, and has been poorly characterized. Here we demonstrate that this WH2 binds profilin-actin with higher affinity than actin alone. The results are consistent with a model whereby allosteric modulation of affinity drives the transition of profilin-actin from the poly-Pro region to the WH2 and then to the barbed end of the filament during elongation. Therefore, the function of the WH2 in Ena/VASP appears to be to "process" profilin-actin for its incorporation at the barbed end of the growing filament. Conformational changes in the newly incorporated actin subunit, resulting either from nucleotide hydrolysis or from the G- to F-actin transition, may serve as a "sensor" for the processive stepping of Ena/VASP. Conserved domain architecture suggests that WASP may work similarly. 相似文献
996.
Nidia N Gomez Roberto C Davicino Veronica S Biaggio German A Bianco Silvina M Alvarez Patricia Fischer Lucas Masnatta Gabriel A Rabinovich María S Gimenez 《Nitric oxide》2006,14(1):30-38
Reactive oxygen and nitrogen species have been implicated in the pathogenesis of pulmonary diseases. The goal of this study was to measure the response of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 enzymes (COX-2) in lung with moderate zinc deficiency. Adult male Wistar rats were divided into two groups receiving (1) a zinc-deficient diet (ZD) or (2) a zinc-adequate control diet. After 2 months of treatment, the zinc-deficient group showed a significant pulmonary edema. This was associated to a reduction of protein thiols and to a significant increase of metallothionein and glutathione disulfide levels. In addition, a higher serum and lung NO production in ZD group was positively related to the higher activity and expression of iNOS and COX-2 found in lungs. Western blot analysis revealed increased IkappaBalpha degradation, an indicator of NF-kappaB activation in ZD lungs. Anatomopathologic analysis of ZD lungs showed an increase of connective tissue fibers with an influx of polymorphonuclear cells. These cells and type II cells from the alveoli showed specific immunohistochemical signals for iNOS. The conclusion is that, during the development of zinc-deficiency, iNOS activity increases in lung and contributes to lung injury. Zinc deficiency implications must be taken into account to design therapies and public health interventions involving targeted zinc supplementation for high-risk subjects or certain diseases, such as asthma. 相似文献
997.
Angélica Flores Jorge O Rodríguez María T Palafox Griselda Meléndez Ana I Barco Roberto Chavira M Esther Cruz Roberto Domínguez 《Reproductive biology and endocrinology : RB&E》2006,4(1):11-10
The presence of asymmetry in the capacity of the left and right ovaries to secrete testosterone was analyzed by studying the
effects of hemiovariectomy along the estrus cycle one hour after surgery. The effects of ether anesthesia on hormone serum
levels were also analyzed. 相似文献
998.
Vigna-Perez M Hernández-Castro B Paredes-Saharopulos O Portales-Pérez D Baranda L Abud-Mendoza C González-Amaro R 《Arthritis research & therapy》2006,8(3):R83-9
We studied the clinical and immunological effects of Rituximab (anti-CD20) therapy in patients with lupus nephritis. In an
open clinical trial, 22 patients with active systemic lupus erythematosis and renal involvement (mainly class III and IV according
to the WHO classification) that was refractory to conventional therapy were studied. In all these patients, Rituximab (0.5
to 1.0 g at days 1 and 15) was added to the immunosuppressive therapy and its therapeutic effect was evaluated. In addition,
the levels and function of regulatory T lymphocytes and the apoptosis of immune cells were assessed. We found a significant
reduction in disease activity (p < 0.05, MEX-SLEDAI index), and proteinuria (p < 0.05) at days 60 and 90 of Rituximab therapy. Although most patients showed improvement in creatinine clearance and erythrocyturia,
no significant changes in these parameters were detected. In most patients (20/22), B cell depletion was observed, but no
clear-cut effect of Rituximab on complement levels or auto-antibody titers was detected (p > 0.05 in all cases). One patient died at day 70 with invasive histoplasmosis. No important adverse effects of Rituximab
therapy were registered in other patients. A significant enhancement in the levels of different CD4+ regulatory cells (TREG, Th3, Tr1), but not CD8+ Ts lymphocytes, was observed at day 30. This increase was sustained for TREG cells at day 90, and accompanied by an improvement in their regulatory function. In addition, we observed an unexpected increase
in the apoptosis of T cells at day 30. Interestingly, the enhancement in the suppressive function of TREG cells was not observed in the two patients that showed the poorest clinical response to Rituximab. We conclude that the data
obtained in this open clinical trial suggest that Rituximab is a promising candidate for randomized controlled trials in patients
with lupus nephritis refractory to the conventional immunosuppressive therapy. The effects of Rituximab on regulatory cells
and apoptosis of T lymphocytes are interesting and its possible role in the putative effect of this biological agent in systemic
lupus erythematosis deserves additional studies. 相似文献
999.
Castaneda LE Sabat P Gonzalez SP Nespolo RF 《Physiological and biochemical zoology : PBZ》2006,79(5):919-926
Anuran metamorphosis is one of the most spectacular processes in nature. Metamorphosis entails morphological transformations and extensive changes in feeding habits, such as transforming from an herbivore to a carnivore. This phenomenon is especially sensitive to environmental cues. We studied the phenotypic plasticity of intestinal morphology and enzyme activity in tadpoles of the Chilean giant frog Caudiverbera caudiverbera. We tested the effects of diet and temperature using a factorial design, which included a control of nontreated individuals. There was no significant effect of diet treatment (i.e., low- vs. high-quality diet) on any of the measured variables, including external morphology. We found significant effects of temperature on morphological traits. Temperature treatment also had significant effects on aminopeptidase-N and maltase activity. Both enzymes exhibited complex interactions with temperature along the intestine. Gut size varied significantly among temperatures, with intestines from warm-treated individuals smaller than the intestines from control and cold-treated tadpoles. Our findings suggest that phenotypic plasticity of intestinal morphology and physiology exists in larvae of this species, at least in response to temperature. However, we did not detect clear effects of diet or temperature on the timing of metamorphosis. 相似文献
1000.
Fuentes M Pessela BC Mateo C Palomo JM Batalla P Fernandez-Lafuente R Guisan JM 《Biomacromolecules》2006,7(4):1357-1361
Diluted solutions of bovine serum albumin (BSA) (e.g., 0.1 mg /mL) do not form detectable protein large aggregates. Using gel-filtration experiments, we determined that a diluted solution of BSA is 97% monomeric BSA and 3% dimeric. The adsorption of this diluted BSA on highly activated anionic exchangers (e,g., having 40 micromol/wet g) keeps this mainly monomeric form. When supports activated with 2 micromol/wet g are used, only dimers become adsorbed to the support, accounting for 100% of the offered BSA. When the diluted BSA solution is offered to very mildly activated anionic exchangers (even only 0.125 micromol/wet g), an unexpected adsorption of most of the BSA on the support was also observed. These very slightly activated supports are only able to adsorb very large proteins or very large protein-protein complexes, larger than BSA dimers. In fact, a rapid cross-linking of the adsorbed BSA with dextran-aldehyde reveals the formation of very large BSA-BSA complexes with molecular mass higher than 500 000 Da, complexes that may be observed for soluble BSA with very high concentrations but are not detectable at 0.1 mg/mL. Moreover, the size of the aggregates strongly depends on the concentration of the ionized groups on the support: the less activated the supports are, the higher the sizes of the complexes. It seems that the interaction of the BSA molecules on the margins of the BSA aggregate with the groups on the support may stabilize the whole protein aggregate, although some components are not interacting with the support. Aggregates could account for more than 40% of the BSA in the solution after 50 h of incubation. However, only these large BSA aggregates were adsorbed in the support. 相似文献