The effects of copper ions on the synthesis of periplasmic and membrane proteins in Acidithiobaeillus ferrooxidans as analyzed by SDS-PAGE and 2D-PAGE

The effects of 200 mM copper ions on the synthesis of membrane and periplasmic proteins were investigated in iron-grown cells of Acidithiobacillus ferrooxidans (At. ferrooxidans). Total membrane protein profiles of cells grown in the absence of copper ions (unadapted cells) and in the presence of copper ions (copper-adapted cells) were compared by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Crude preparations of outer membrane and periplasmic proteins were analyzed by SDS-PAGE. The synthesis of proteins was diminished or increased in the presence of copper ions. Low molecular weight proteins (< 14 kDa) were significantly repressed by copper. These proteins are probably acidic proteins located in the outer membrane. An over-expression of a periplasmic protein of about 17 kDa was detected in the copper-adapted cells and was assumed to be rusticyanin, a 16.5-kDa periplasmic copper protein present in At. ferrooxidans cells and involved in the electron-transport chain of the iron oxidation pathway. To our knowledge, this is the first report of a possible involvement of the rusticyanin and outer membrane proteins in the mechanism of copper resistance in At. ferrooxidans. (C) 2003 Elsevier B.V. All rights reserved.

Protection of calves against Haemonchus placei and Haemonchus contortus after immunization with gut membrane proteins from H. contortus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparative genomics of two Leptospira interrogans serovars reveals novel insights into physiology and pathogenesis

Leptospira species colonize a significant proportion of rodent populations worldwide and produce life-threatening infections in accidental hosts, including humans. Complete genome sequencing of Leptospira interrogans serovar Copenhageni and comparative analysis with the available Leptospira interrogans serovar Lai genome reveal that despite overall genetic similarity there are significant structural differences, including a large chromosomal inversion and extensive variation in the number and distribution of insertion sequence elements. Genome sequence analysis elucidates many of the novel aspects of leptospiral physiology relating to energy metabolism, oxygen tolerance, two-component signal transduction systems, and mechanisms of pathogenesis. A broad array of transcriptional regulation proteins and two new families of afimbrial adhesins which contribute to host tissue colonization in the early steps of infection were identified. Differences in genes involved in the biosynthesis of lipopolysaccharide 0 side chains between the Copenhageni and Lai serovars were identified, offering an important starting point for the elucidation of the organism's complex polysaccharide surface antigens. Differences in adhesins and in lipopolysaccharide might be associated with the adaptation of serovars Copenhageni and Lai to different animal hosts. Hundreds of genes encoding surface-exposed lipoproteins and transmembrane outer membrane proteins were identified as candidates for development of vaccines for the prevention of leptospirosis.

Presence and distribution of the endosymbiont Wolbachia among Solenopsis spp. (Hymenoptera: Formicidae) from Brazil and its evolutionary history

Wolbachia are intracellular bacteria that commonly infect arthropods. Its prevalence among ants of the genus Solenopsis is high. In the present study, the presence and distribution of these endosymbionts was examined among populations of Solenopsis spp. from Brazil. A phylogenetic analysis based on the wsp gene was conducted to infer the evolutionary history of Wolbachia infections within the populations surveyed. A high frequency of Wolbachia bacteria was observed among the genus Solenopsis, 51% of the colonies examined were infected. Incidence was higher in populations from southern Brazil. However, little genetic variability was found among different Wolbachia strains within supergroups A and B. Our findings also suggest that horizontal transmission events can occur through the social parasite S. daguerrei. © 2012 Elsevier Inc..

Effects of Yersinia enterocolitica O:3 derivatives on B lymphocyte activation in vivo

The potential sequelae of intestinal infection with Yersinia enterocolitica include reactive arthritis, erythema nodosum, Reiter's syndrome and other autoimmune diseases. The role of the immune response in the pathogenesis of these diseases has not been fully defined, but autoimmune manifestations may be a consequence of the increase in autoantibodies as a result of polyclonal B-cell activation induced by Yersinia. We investigated the effects of Y enterocolitica 0:3 derivatives on B lymphocyte activation in vivo. Groups of five specific pathogen free (SPF) Swiss mice were inoculated with bacterial cell extract, Yersinia outermembrane proteins (Yops) or lipopolysaccharide (LPS) obtained from Y enterocolitica 0:3 and their immunoglobulin-secreting spleen cells were detected by isotype-specific protein A plaque assay. The presence of specific anti-Yersinia antibodies and autoantibodies was determined in mouse sera by ELISA. In all experiments a marked increase in the number of secretory cells of different isotypes was observed as early as the third day after inoculation. IgG and IgM anti-Yersinia antibodies were detected in the sera of all inoculated mice, and autoantibodies against myosin in the sera of those inoculated with bacterial cell extract. The sera from animals stimulated with LPS reacted with myelin, actin and laminin, while the sera from mice inoculated with Yops reacted with myelin, thyroglobulin and cardiolipin. These results suggest that SPF Swiss mice inoculated with any one of the Y enterocolitica derivatives tested exhibited polyclonal activation of B lymphocytes as a result of stimulation by various bacterial components and not only LPS stimulation.

Analysis of proteins from membrane and soluble fractions of Giardia duodenalis trophozoites of two Brazilian axenic strains

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Plant uncoupling mitochondrial proteins

Uncoupling proteins (UCPs) are membrane proteins that mediate purine nucleotide-sensitive free fatty acid-activated H(+) flux through the inner mitochondrial membrane. After the discovery of UCP in higher plants in 1995, it was acknowledged that these proteins are widely distributed in eukaryotic organisms. The widespread presence of UCPs in eukaryotes implies that these proteins may have functions other than thermogenesis. In this review, we describe the current knowledge of plant UCPs, including their discovery, biochemical properties, distribution, gene family, gene expression profiles, regulation of gene expression, and evolutionary aspects. Expression analyses and functional studies on the plant UCPs under normal and stressful conditions suggest that UCPs regulate energy metabolism in the cellular responses to stress through regulation of the electrochemical proton potential (Delta mu(H)+) and production of reactive oxygen species.

Photoacoustic spectroscopy of aromatic amino acids in proteins

This paper concerns the use of photoacoustic spectroscopy (PAS) to study the presence of aromatic amino acid in proteins. We examined the aromatic amino acids in six proteins with well-known structures using absorption spectra of near ultraviolet PAS over the wavelength range 240-320 nm. The fundamental understanding of the physical and chemical properties that govern the absorption of light and a subsequent release of heat to generate a transient pressure wave was used to test the concept of monitoring aromatic amino acids with this method. Second derivative spectroscopy in the ultraviolet region of proteins was also used to study the regions surrounding the aromatics and the percentage area in each band was related in order to determine the contribution in function of the respective molar extinction coefficients for each residue. Further investigation was conducted into the interaction between sodium dodecyl sulphate (SDS) and bothropstoxin-I (BthTx-I), with the purpose of identifying the aromatics that participate in the interaction. The clear changes in the second derivative and curve-fitting procedures suggest that initial SDS binding to the tryptophan located in the dimer interface and above 10 SDS an increased intensity between 260 and 320 nm, demonstrating that the more widespread tyrosine and phenylalanine residues contribute to the SDS/BthTx-I interactions. These results demonstrate the potential of near UV-PAS for the investigation of membrane proteins/detergent complexes in which light scattering is significant.

Secretoma da bactéria fitopatogênica Xanthomonas citri subsp. citri

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

TLR4 and CD14 receptors expressed in rat pineal gland trigger NFKB pathway

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The Potential of p38 MAPK Inhibitors to Modulate Periodontal Infections

Periodontal disease initiation and progression occurs as a consequence of the host immune inflammatory response to oral pathogens. The innate and acquired immune systems are critical for the proper immune response. LPS, an outer membrane constituent of periodontal pathogenic bacteria, stimulates the production of inflammatory cytokines IL-1 beta TNF alpha IL-6 and RANKL either directly or indirectly. In LPS-stimulated cells, the induction of cytokine expression requires activation of several signaling pathways including the p38 MAPK pathway. This review will discuss the significance of the p38 MAPK pathway in periodontal disease progression and the potential therapeutic consequences of pharmacological antagonism of this pathway in the treatment of periodontal diseases.

Aquaporin 9 (AQP9) localization in the adult dog testis excurrent ducts by immunohistochemistry

Aquaporins (AQPs) are small, intrinsic membrane proteins that are present in many cell types involved in fluid transport. AQP9 is a major apical water channel that is expressed throughout the efferent ducts, epididymis, and vas deferens, as well as in other regions of the human and rodent male reproductive tract. The target of this study was to examine the expression of AQP9 in epithelial cells in the adult dog efferent ducts, epididymis, and vas deferens. Samples of dog male reproductive tract comprising fragments of the testis; initial segment, caput, corpus, and cauda of the epididymis; and vas deferens were obtained from eight adult mongrel dogs. Immunohistochemistry and Western blotting procedures were used to show AQP9 localization and distribution. AQP9 expression was not detected either in dog seminiferous tubules or rete testis. However, apical labeling for AQP9 was detected in the different regions of epididymis and vas deferens, with the reaction being less intense in the caput epididymis. Thus, AQP9 is abundantly expressed in dog male reproductive tract, in which it is an important apical pathway for transmembrane flow of water and neutral solutes.

Profiling the Proteome of the Venom from the Social Wasp Polybia paulista: A Clue to Understand the Envenoming Mechanism

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

An ultraviolet photoacoustic spectroscopy study of the interaction between Lys49-phospholipase A(2) and amphiphilic molecules

We have used near ultraviolet photoacoustic spectroscopy (PAS) over the wavelength range 240-320 nm to investigate the complex formed between the homodimeric bothropstoxin-I, a lysine-49-phospholipase A(2) from the venom of Bothrops jararacussu (BthTx-I), with the anionic amphiphile sodium dodecyl sulfate (SDS). At molar ratios > 10, the complex developed a significant light scatter, accompanied by a decrease in the intrinsic tryptophan fluorescence intensity emission (ITFE) of the protein, and an increase in the near UV-PAS signal. Difference PAS spectroscopy at SDS/BthTx-I ratios < 8 were limited to the region 280-290 nm, suggesting initial SDS binding to the tryptophan 77 located at the dimer interface. At SDS/BthTx-I ratios > 10, the intensity between 260 and 320 nm increases demonstrating that the more widespread tyrosine and phenylalanine residues contribute to the SDS/BthTx-I interaction. PAS signal phase changes at wavelengths specific for each aromatic residue suggest that the Trp77 becomes more buried on SDS binding, and that protein structural changes and dehydration may alter the microenvironments of Tyr and Phe residues. These results demonstrate the potential of near UV-PAS for the investigation of membrane proteins/detergent complexes in which light scatter is significant. (c) 2006 Elsevier B.V. All rights reserved.

Coat protein and RNAs of Cole latent virus are not present within chloroplasts of Chenopodium quinoa-infected cells

O vírus latente da couve (Cole latent virus, CoLV), gênero Carlavirus, foi estudado, por microscopia eletrônica de transmissão e técnicas bioquímicas, em relação à ultra-estrutura das células infetadas de Chenopodium quinoa, e de sua associação com os cloroplastos. O CoLV foi observado como partículas dispersas pelo citoplasma entremeadas com vesículas membranosas e ribossomos e/ou como densas massas de partículas. Estes partículas reagiram por imunomarcação com anti-soro policlonal para o CoLV. Morfologicamente, cloroplastos, mitocôndrias e núcleos mostraram-se inalterados e partículas virais não foram encontradas dentro dessas organelas. Entretanto, agregados de partículas virais foram freqüentemente vistos em associação com a membrana externa dos cloroplastos e ocasionalmente com peroxissomos. Cloroplastos foram purificados em gradiente de Percoll e as proteínas e os RNA foram extraídos e analisados, respectivamente, por Western blot e Northern blot. Proteína capsidial e RNA associados ao CoLV não foram detectados nessa organela. Os resultados aqui obtidos indicam que a associação CoLV/cloroplastos, observada nos estudos de microscopia eletrônica, é possivelmente um evento casual dentro da célula hospedeira e que o vírus não se multiplica dentro dessa organela.