Lipid-free Antigen B subunits from echinococcus granulosus: oligomerization, ligand binding, and membrane interaction properties

Background: The hydatid disease parasite Echinococcus granulosus has a restricted lipid metabolism, and needs to harvest essential lipids from the host. Antigen B (EgAgB), an abundant lipoprotein of the larval stage (hydatid cyst), is thought to be important in lipid storage and transport. It contains a wide variety of lipid classes, from highly hydrophobic compounds to phospholipids. Its protein component belongs to the cestode-specific Hydrophobic Ligand Binding Protein family, which includes five 8-kDa isoforms encoded by a multigene family (EgAgB1-EgAgB5). How lipid and protein components are assembled into EgAgB particles remains unknown. EgAgB apolipoproteins self-associate into large oligomers, but the functional contribution of lipids to oligomerization is uncertain. Furthermore, binding of fatty acids to some EgAgB subunits has been reported, but their ability to bind other lipids and transfer them to acceptor membranes has not been studied.<p></p> Methodology/Principal Findings: Lipid-free EgAgB subunits obtained by reverse-phase HPLC were used to analyse their oligomerization, ligand binding and membrane interaction properties. Size exclusion chromatography and cross-linking experiments showed that EgAgB8/2 and EgAgB8/3 can self-associate, suggesting that lipids are not required for oligomerization. Furthermore, using fluorescent probes, both subunits were found to bind fatty acids, but not cholesterol analogues. Analysis of fatty acid transfer to phospholipid vesicles demonstrated that EgAgB8/2 and EgAgB8/3 are potentially capable of transferring fatty acids to membranes, and that the efficiency of transfer is dependent on the surface charge of the vesicles.<p></p> Conclusions/Significance: We show that EgAgB apolipoproteins can oligomerize in the absence of lipids, and can bind and transfer fatty acids to phospholipid membranes. Since imported fatty acids are essential for Echinococcus granulosus, these findings provide a mechanism whereby EgAgB could engage in lipid acquisition and/or transport between parasite tissues. These results may therefore indicate vulnerabilities open to targeting by new types of drugs for hydatidosis therapy.<p></p&gt

Lipid-Free Antigen B Subunits from <i>Echinococcus granulosus</i>: Oligomerization, Ligand Binding, and Membrane Interaction Properties

The hydatid disease parasite Echinococcus granulosus has a restricted lipid metabolism, and needs to harvest essential lipids from the host. Antigen B (EgAgB), an abundant lipoprotein of the larval stage (hydatid cyst), is thought to be important in lipid storage and transport. It contains a wide variety of lipid classes, from highly hydrophobic compounds to phospholipids. Its protein component belongs to the cestode-specific Hydrophobic Ligand Binding Protein family, which includes five 8-kDa isoforms encoded by a multigene family (EgAgB1-EgAgB5). How lipid and protein components are assembled into EgAgB particles remains unknown. EgAgB apolipoproteins self-associate into large oligomers, but the functional contribution of lipids to oligomerization is uncertain. Furthermore, binding of fatty acids to some EgAgB subunits has been reported, but their ability to bind other lipids and transfer them to acceptor membranes has not been studied. Lipid-free EgAgB subunits obtained by reverse-phase HPLC were used to analyse their oligomerization, ligand binding and membrane interaction properties. Size exclusion chromatography and cross-linking experiments showed that EgAgB8/2 and EgAgB8/3 can self-associate, suggesting that lipids are not required for oligomerization. Furthermore, using fluorescent probes, both subunits were found to bind fatty acids, but not cholesterol analogues. Analysis of fatty acid transfer to phospholipid vesicles demonstrated that EgAgB8/2 and EgAgB8/3 are potentially capable of transferring fatty acids to membranes, and that the efficiency of transfer is dependent on the surface charge of the vesicles. We show that EgAgB apolipoproteins can oligomerize in the absence of lipids, and can bind and transfer fatty acids to phospholipid membranes. Since imported fatty acids are essential for Echinococcus granulosus, these findings provide a mechanism whereby EgAgB could engage in lipid acquisition and/or transport between parasite tissues. These results may therefore indicate vulnerabilities open to targeting by new types of drugs for hydatidosis therapy.Instituto de Investigaciones Bioquímicas de La PlataFacultad de Ciencias Médica

Serum amyloid A is a positive acute phase protein in Russian sturgeon challenged with Aeromonas hydrophila

The immune system of sturgeons, one of the most ancient and economically valuable fsh worldwide, is poorly understood. The lack of molecular tools and data about infection biomarkers hinders the possibility to monitor sturgeon health during farming and detect infection outbreaks. To tackle this issue, we mined publicly available transcriptomic datasets and identifed putative positive acute-phase proteins (APPs) of Russian sturgeons that could be induced by a bacterial infection and monitored using non-invasive methods. Teleost literature compelled us to focus on fve promising candidates: hepcidin, a warm acclimation associated hemopexin, intelectin, serum amyloid A protein (SAA) and serotransferrin. Among them, SAA was the most upregulated protein at the mRNA level in the liver of sturgeons challenged with heat-inactivated or live Aeromonas hydrophila. To assess whether this upregulation yielded increasing SAA levels in circulation, we developed an in-house ELISA to quantify SAA levels in sturgeon serum. Circulating SAA rose upon bacterial challenge and positively correlated with hepatic saa expression. This is the frst time serum SAA has been quantifed in an Actinopterygii fsh. Since APPs vary across diferent fsh species, our work sheds light on sturgeon acute-phase response, revealing that SAA is a positive APP with potential value as infection biomarker

El entrenamiento intervalado de alta intensidad mejora el rendimiento específico en los atletas de taekwondo

[ES] Los métodos de entrenamiento específicos son un aspecto importante en la preparación de los atletas de taekwondo. El propósito de este estudio fue investigar el efecto de un programa de entrenamiento intervalado de alta intensidad (EIAI) de corta duración con técnicas específicas de taekwondo sobre el rendimiento anaeróbico. Doce atletas de taekwondo fueron asignados al azar a un grupo control (n=6) o grupo experimental (n=6). El protocolo experimental consistió en 3 bloques de 6 series de esfuerzo total de 10 segundos, con recuperación pasiva de 10 segundos entre series e intervalos de descanso de 1 minuto entre bloques, realizado 3 días por semana durante 4 semanas. Se realizó un análisis de varianza de tres vías (ANOVA) (grupo, serie y tiempo) con mediciones repetidas en los dos últimos factores para comparar el rendimiento durante cada serie de la prueba Frequency Speed Kick Test(FSKT) y un ANOVA de dos vías (grupo y tiempo) con mediciones repetidas se utilizó para comparar el número total de patadas y el índice de fatiga de patadas (IFP). Ambos grupos mantuvieron su entrenamiento regular de taekwondo, que era exactamente el mismo. Antes y después del programa de entrenamiento, los atletas realizaron el FSKT. El grupo experimental aumentó el rendimiento (p <0,01) en cada una de las cinco series de FSKT y en el número total de patadas (p <0,001). No se observó diferencia estadística en el grupo control después de 4 semanas o entre el grupo control y el grupo experimental en ningún momento. Un programa de EIAI de corta duración con técnicas específicas de taekwondo mejoró el rendimiento anaeróbico medido a través del FSKT. Sin embargo, el índice de fatiga no cambió.[EN] Specific training methods is an important aspect in the preparation of taekwondo athletes.The purpose of this study was to investigate the effect of a short-duration high-intensity interval training (HIIT) program with specific taekwondo techniques on anaerobic performance.Twelve taekwondo athletes were randomized into a control (n=6) or experimental groups (n=6). The experimental protocol consisted of 3 blocks of 6 sets of 10s all-out effort, with 10s passive recovery between sets and 1-min rest interval between blocks, conducted 3 days per week during 4-weeks. A three-way analysis of variance (ANOVA) (group, set and moment) with repeated measurements in the two last factors was conducted to compare the performance during each set of the Frequency Speed Kick Test (FSKT), and an ANOVA two-way (group and moment) with repeated measurements was used to compare the total number of kicks and kick decrement index (KDI). Both groups maintained their regular taekwondo training, which was exactly the same. Before and after the training program the athletes performed the FSKT.The experimental group increased (p<0.01) performance in each of the five sets of the FSKT and in the total number of kicks (p<0.001). No statistical difference was observed in the control group after 4-weeks or between the control and experimental group in any moment. A short-duration HIIT program with specific taekwondo techniques improved anaerobic performance measured through the FSKT. However, the fatigue index did not change.[PT] Os métodos de treinamento específicos são um aspecto importante na preparação física dos atletas de taekwondo. O propósito deste estudo foi investigar o efeito de um programa de treinamento intervalado de alta intensidade (TIAI), de curta duração, com técnicas específicas de taekwondo sobre o desempenho anaeróbio. Doze atletas de taekwondo foram alocados aleatoriamente a um grupo controle (n=6) ou a um grupo experimental (n=6). O protocolo experimental consistiu em 3 blocos de 6 séries de esforço com duração de 10 segundos, com recuperação passiva de 10 segundos entre as séries e intervalos de descanso de 1 minuto entre os blocos, realizado 3 dias por semana durante 4 semanas. Foi utilizada a análise de variância (ANOVA) a três fatores (grupo, série e tempo) com medidas repetidas nos dois últimos fatores para comparar o desempenho durante cada série do Frequency Speed Kick Test (FSKT) e uma ANOVA a dois fatores (grupo e tempo) com medidas repetidas foi utilizada para comparar o número total de chutes e o índice de fadiga de chutes (IFC). Os dois grupos mantiveram seu treinamento regular de taekwondo, o qual era exatamente o mesmo. Antes e depois do programa de treinamento os atletas realizaram o FSKT. O grupo experimental aumentou o desempenho (p <0,01) em cada uma das cinco séries do FSKT e no número total de chutes (p<0,001). Não foi observada diferença estatística no grupo controle depois de 4 semanas ou entre o grupo controle e o grupo experimental em nenhum momento. Um programa de TIAI, de curta duração, com técnicas específicas de taekwondo melhorou o desempenho anaeróbio medido por meio do FSKT. Contudo, o IFC não mudou

Echinococcus granulosus antigen B: A Hydrophobic Ligand Binding Protein at the host–parasite interface

Lipids are mainly solubilized by various families of lipid binding proteins which participate in their transport between tissues as well as cell compartments. Among these families, Hydrophobic Ligand Binding Proteins (HLBPs) deserve special consideration since they comprise intracellular and extracellular members, are able to bind a variety of fatty acids, retinoids and some sterols, and are present exclusively in cestodes. Since these parasites have lost catabolic and biosynthetic pathways for fatty acids and cholesterol, HLBPs are likely relevant for lipid uptake and transportation between parasite and host cells. Echinococcus granulosus antigen B (EgAgB) is a lipoprotein belonging to the HLBP family, which is very abundant in the larval stage of this parasite. Herein, we review the literature on EgAgB composition, structural organization and biological properties, and propose an integrated scenario in which this parasite HLBP contributes to adaptation to mammalian hosts by meeting both metabolic and immunomodulatory parasite demands.Fil: Silva Alvarez, Maria Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; Argentina. Universidad de la República. Facultad de Ciencias; UruguayFil: Folle, Ana Maite. Universidad de la República. Facultad de Ciencias; UruguayFil: Ramos, Ana Lía. Universidad de la República. Facultad de Ciencias; UruguayFil: Zamarreño, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; ArgentinaFil: Costabel, Marcelo Daniel. Universidad Nacional del Sur; ArgentinaFil: García Zepeda, Eduardo. Universidad Nacional Autónoma de México; MéxicoFil: Salinas, Gustavo. Universidad de la República. Facultad de Ciencias; UruguayFil: Córsico, Betina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata ; ArgentinaFil: Ferreira, Ana María. Universidad del Uruguay. Facultad de Ciencias; Urugua

O conjunto dos números inteiros como campo experimental para introdução da álgebra na educação básica

Nesta sinopse de trabalhos realizados com pré-vestibulandos de dois grupos de níveis socio-econômicos diferentes são analisadas produções e dificuldades de alunos diante de situações-problema envolvendo conteúdos de divisibilidade, paridade e padrões em sequências numéricas, tomando como base de cálculo o conjunto dos números inteiros. Para o desenvolvimento experimental foram elaboradas sequências de atividades desenvolvidas em encontros semanais com os participantes. De modo geral, os alunos se envolveram nas atividades, o que permitiu analisar dificuldades, conceitos mobilizados e indícios de aprendizagens, não só quanto à forma de apresentação das produções escritas, mas também quanto aos níveis de conhecimento dos conteúdos aritméticos e algébricos estudados

Echinococcus granulosus Antigen B binds to monocytes and macrophages modulating cell response to inflammation

Background: Antigen B (EgAgB) is an abundant lipoprotein released by the larva of the cestode Echinococcus granulosus into the host tissues. Its protein moiety belongs to the cestode-specific family known as hydrophobic ligand binding protein (HLBP), and is encoded by five gene subfamilies (EgAgB8/1-EgAgB8/5). The functions of EgAgB in parasite biology remain unclear. It may play a role in the parasite's lipid metabolism since it carries host lipids that E. granulosus is unable to synthesise. On the other hand, there is evidence supporting immuno-modulating activities in EgAgB, particularly on innate immune cells. Both hypothetical functions might involve EgAgB interactions with monocytes and macrophages, which have not been formally analysed yet. Methods: EgAgB binding to monocytes and macrophages was studied by flow cytometry using inflammation-recruited peritoneal cells and the THP-1 cell line. Involvement of the protein and phospholipid moieties in EgAgB binding to cells was analysed employing lipid-free recombinant EgAgB subunits and phospholipase D treated-EgAgB (lacking the polar head of phospholipids). Competition binding assays with plasma lipoproteins and ligands for lipoprotein receptors were performed to gain information about the putative EgAgB receptor(s) in these cells. Arginase-I induction and PMA/LPS-triggered IL-1β, TNF-α and IL-10 secretion were examined to investigate the outcome of EgAgB binding on macrophage response. Results: Monocytes and macrophages bound native EgAgB specifically; this binding was also found with lipid-free rEgAgB8/1 and rEgAgB8/3, but not rEgAgB8/2 subunits. EgAgB phospholipase D-treatment, but not the competition with phospholipid vesicles, caused a strong inhibition of EgAgB binding activity, suggesting an indirect contribution of phospholipids to EgAgB-cell interaction. Furthermore, competition binding assays indicated that this interaction may involve receptors with affinity for plasma lipoproteins. At functional level, the exposure of macrophages to EgAgB induced a very modest arginase-I response and inhibited PMA/LPS-mediated IL-1β and TNF-α secretion in an IL-10-independent manner. Conclusion: EgAgB and, particularly its predominant EgAgB8/1 apolipoprotein, are potential ligands for monocyte and macrophage receptors. These receptors may also be involved in plasma lipoprotein recognition and induce an anti-inflammatory phenotype in macrophages upon recognition of EgAgB