Metallochaperones Are Needed for Mycobacterium tuberculosis and Escherichia coli Nicotinamidase-Pyrazinamidase Activity.

Mycobacterium tuberculosis nicotinamidase-pyrazinamidase (PZAse) is a metalloenzyme that catalyzes conversion of nicotinamide-pyrazinamide to nicotinic acid-pyrazinoic acid. This study investigated whether a metallochaperone is required for optimal PZAse activity. M. tuberculosis and Escherichia coli PZAses (PZAse-MT and PZAse-EC, respectively) were inactivated by metal depletion (giving PZAse-MT-Apo and PZAse-EC-Apo). Reactivation with the E. coli metallochaperone ZnuA or Rv2059 (the M. tuberculosis analog) was measured. This was repeated following proteolytic and thermal treatment of ZnuA and Rv2059. The CDC1551 M. tuberculosis reference strain had the Rv2059 coding gene knocked out, and PZA susceptibility and the pyrazinoic acid (POA) efflux rate were measured. ZnuA (200 μM) achieved 65% PZAse-EC-Apo reactivation. Rv2059 (1 μM) and ZnuA (1 μM) achieved 69% and 34.3% PZAse-MT-Apo reactivation, respectively. Proteolytic treatment of ZnuA and Rv2059 and application of three (but not one) thermal shocks to ZnuA significantly reduced the capacity to reactivate PZAse-MT-Apo. An M. tuberculosis Rv2059 knockout strain was Wayne positive and susceptible to PZA and did not have a significantly different POA efflux rate than the reference strain, although a trend toward a lower efflux rate was observed after knockout. The metallochaperone Rv2059 restored the activity of metal-depleted PZAse in vitro Although Rv2059 is important in vitro, it seems to have a smaller effect on PZA susceptibility in vivo. It may be important to mechanisms of action and resistance to pyrazinamide in M. tuberculosis Further studies are needed for confirmation.IMPORTANCE Tuberculosis is an infectious disease caused by the bacterium Mycobacterium tuberculosis and remains one of the major causes of disease and death worldwide. Pyrazinamide is a key drug used in the treatment of tuberculosis, yet its mechanism of action is not fully understood, and testing strains of M. tuberculosis for pyrazinamide resistance is not easy with the tools that are presently available. The significance of the present research is that a metallochaperone-like protein may be crucial to pyrazinamide's mechanisms of action and of resistance. This may support the development of improved tools to detect pyrazinamide resistance, which would have significant implications for the clinical management of patients with tuberculosis: drug regimens that are appropriately tailored to the resistance profile of a patient's individual strain lead to better clinical outcomes, reduced onward transmission of infection, and reduction of the development of resistant strains that are more challenging and expensive to treat

Determining R-parity violating parameters from neutrino and LHC data

In supersymmetric models neutrino data can be explained by R-parity violating operators which violate lepton number by one unit. The so called bilinear model can account for the observed neutrino data and predicts at the same time several decay properties of the lightest supersymmetric particle. In this paper we discuss the expected precision to determine these parameters by combining neutrino and LHC data and discuss the most important observables. We show that one can expect a rather accurate determination of the underlying R-parity parameters assuming mSUGRA relations between the R-parity conserving ones and discuss briefly also the general MSSM as well as the expected accuracies in case of a prospective e+ e- linear collider. An important observation is that several parameters can only be determined up to relative signs or more generally relative phases.Comment: 13 pages, 13 figure

Produtividade e precocidade de genótipos da coleção nuclear de feijão (Phaseolus vulgaris L.) da Embrapa em condições de deficiência hídrica moderada.

O trabalho teve como objetivo conduzir uma avaliação preliminar de genótipos de feijão, para subsidiar o programa de melhoramento da Embrapa Arroz e Feijão direcionado para regiões com probabilidade de ocorrência de deficiência hídrica durante a época normal do desenvolvimento da cultura.CONAF

Avaliação de famílias F5:8 de uma população de mapeamento, do cruzamento BAT 477 x BRS Pérola, sob condições de deficiência hídrica.

Este trabalho objetivou avaliar famílias F5:8 de uma população de mapeamento, do cruzamento BAT 477 x BRS Pérola, em condições de deficiência hídrica na Estação Experimental da Emater, em Porangatu, GO.CONAF

Tolerância à deficiência hídrica em feijoeiro: divergência fenotípica na condutância estomática, transpiração e fotossíntese.

O trabalho teve como objetivo caracterizar a variabilidade fisiológica da tolerância à deficiência hídrica de genótipos de feijoeiro com divergência fenotípica para tolerância à deficiência hídrica.CONAF

Quantificação dos teores de açúcares, oligossacarídeos e amido em genótipos/ cultivares de soja (Glycine Max (L) Merril) especiais utilizados para alimentação humana.

RESUMO: Na soja, vários componentes, tais como açúcares, aminoácidos, ácidos orgânicos, sais inorgânicos, isoflavonas e saponinas estão relacionados com o sabor. Os açúcares, a sacarose e o amido, podem melhorar o sabor e a textura da soja. O objetivo deste trabalho foi quantificar os teores desses compostos e dos oligossacarídeos, em sementes de 28 genótipos/cultivares do Banco Ativo de Germoplasma da Embrapa Soja, que apresentam características especiais para o melhoramento genético. Os açúcares e os oligossacarídeos foram quantificados pela técnica de cromatografia liquida de alto desempenho (CLAE) e o amido pela metodologia adaptada de Rickard e Behn (1987). Os genótipos PI 417.159 e F83-8119 apresentaram menores teores de oligossacarídeos totais (2,744 e 3,064 g.100 g de massa seca). As cultivares Tambaguro e Koji Amarela foram as que apresentaram teores de sacarose superiores a 6 g.100 g–1 de massa seca(6,327 e 6,162), enquanto que a única cultivar que apresentou um teor superior a 1 g.100g–1–1 de massa seca de amido foi a Tambaguro (1,191). As cultivares Koji Preta, Tamahomare, Tambaguro e BRS 267 foram estatisticamente superiores quando os 3 atributos (oligossacarídeos totais, sacarose e amido) foram avaliados conjuntamente, com o foco em sabor superior. As cultivares Koji Preta, Tamahomare, Tambaguro foram as melhores fontes genéticas indicadas para cruzamentos, pois não são tropicalizadas, enquanto a cultivar BRS 267 pode melhorar as qualidades sensoriais dos produtos processados a partir de soja. Por outro lado, a cultivar Late Giant, devido ao maior teor de oligossacarídeos, é uma fonte genética em potencial para produção de um alimento funcional à base de soja. ABSTRACT: In soybeans, many components such as sugars, amino acids, organic acids, inorganic salts, saponins and isoflavones are related to the flavour. The sugars, sucrose and starch can improve the soybean flavour and texture. The present study aimed to quantify the contents of these compounds and also the oligosaccharides in the seeds from 28 genotypes/cultivars obtained from the Embrapa Soybean Germplasm Bank, that present special characteristics for genetic improvement programmes. The sugars and oligosaccharides were quantified by high-performance liquid chromatography (HPLC) and the starch by methodology adapted from Rickard e Behn (1987). The genotypes PI 417.159 and F83-8119 showed the lowest contents of total oligosaccharides (2.744 and 3.064 g.100 g DW). The cultivars Tambaguro and Koji Amarela showed sucrose levels above 6 g.100 g–1 DW (6.327 and 6.162), and the only cultivar with a starch content above 1 g.100 g–1 DW was Tambaguro (1.191). The cultivars Koji Preta, Tamahomare, Tambaguro and BRS 267 were statistically better when the 3 attributes (total oligosaccharides, sucrose and starch) were analysed together with a focus on better flavour. The cultivars Koji Preta, Tamahomare, Tambaguro were the best genetic sources for breeding because they have not been tropicalized, whilst the cultivar BRS 267 could improve the sensory qualities of processed soybean-based foods. On the other hand, on account of its higher oligosaccharide content, the cultivar Late Giant is a potential genetic source for the production of functional soybean-based foods

Marcador bioquímico para seleção de genótipos de milho tolerantes ao alumínio.

xSuplemento. Edição dos resumos do IX Congresso Brasileiro de Fisiologia Vegetal, 2003, Atibaia, SP

Relações hídricas de genótipos com divergência fenotípica para tolerância à seca.

Objetivou-se estudar a adaptação de genótipos de feijoeiro à deficiência hídrica, por meio da avaliação do potencial da água e da temperatura das folhas.CONAF