Respiration of arsenate and selenate by hyperthermophilic archaea.

Science.gov (United States)

Huber, R; Sacher, M; Vollmann, A; Huber, H; Rose, D

2000-10-01

A novel, strictly anaerobic, hyperthermophilic, facultative organotrophic archaeon was isolated from a hot spring at Pisciarelli Solfatara, Naples, Italy. The rod-shaped cells grew chemolithoautotrophically with carbon dioxide as carbon source, hydrogen as electron donor and arsenate, thiosulfate or elemental sulfur as electron acceptor. H2S was formed from sulfur or thiosulfate, arsenite from arsenate. Organotrophically, the new isolate grew optimally in the presence of an inorganic electron acceptor like sulfur, selenate or arsenate. Cultures, grown on arsenate and thiosulfate or arsenate and L-cysteine, precipitated realgar (As2S2). During growth on selenate, elemental selenium was produced. The G+C content of the DNA was 58.3 mol%. Due to 16S rRNA gene sequence analysis combined with physiological and morphological criteria, the new isolate belongs to the Thermoproteales order. It represents a new species within the genus Pyrobaculum, the type species of which we name Pyrobaculum arsenaticum (type strain PZ6*, DSM 13514, ATCC 700994). Comparative studies with different Pyrobaculum-species showed, that Pyrobaculum aerophilum was also able to grow organotrophically under anaerobic culture conditions in the presence of arsenate, selenate and selenite. During growth on selenite, elemental selenium was formed as final product. In contrast to P. arsenaticum, P. aerophilum could use selenate or arsenate for lithoautotrophic growth with carbon dioxide and hydrogen.

Physical, Chemical, and Biological Methods for the Removal of Arsenic Compounds

Directory of Open Access Journals (Sweden)

K. T. Lim

2014-01-01

Full Text Available Arsenic is a toxic metalloid which is widely distributed in nature. It is normally present as arsenate under oxic conditions while arsenite is predominant under reducing condition. The major discharges of arsenic in the environment are mainly due to natural sources such as aquifers and anthropogenic sources. It is known that arsenite salts are more toxic than arsenate as it binds with vicinal thiols in pyruvate dehydrogenase while arsenate inhibits the oxidative phosphorylation process. The common mechanisms for arsenic detoxification are uptaken by phosphate transporters, aquaglyceroporins, and active extrusion system and reduced by arsenate reductases via dissimilatory reduction mechanism. Some species of autotrophic and heterotrophic microorganisms use arsenic oxyanions for their regeneration of energy. Certain species of microorganisms are able to use arsenate as their nutrient in respiratory process. Detoxification operons are a common form of arsenic resistance in microorganisms. Hence, the use of bioremediation could be an effective and economic way to reduce this pollutant from the environment.

Arsenic and selenium in microbial metabolism

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Stolz, John F.; Basu, Partha; Santini, Joanne M.; Oremland, Ronald S.

2006-01-01

Arsenic and selenium are readily metabolized by prokaryotes, participating in a full range of metabolic functions including assimilation, methylation, detoxification, and anaerobic respiration. Arsenic speciation and mobility is affected by microbes through oxidation/reduction reactions as part of resistance and respiratory processes. A robust arsenic cycle has been demonstrated in diverse environments. Respiratory arsenate reductases, arsenic methyltransferases, and new components in arsenic resistance have been recently described. The requirement for selenium stems primarily from its incorporation into selenocysteine and its function in selenoenzymes. Selenium oxyanions can serve as an electron acceptor in anaerobic respiration, forming distinct nanoparticles of elemental selenium that may be enriched in (76)Se. The biogenesis of selenoproteins has been elucidated, and selenium methyltransferases and a respiratory selenate reductase have also been described. This review highlights recent advances in ecology, biochemistry, and molecular biology and provides a prelude to the impact of genomics studies.

Expression profiling of Crambe abyssinica under arsenate stress identifies genes and gene networks involved in arsenic metabolism and detoxification

Directory of Open Access Journals (Sweden)

Kandasamy Suganthi

2010-06-01

Full Text Available Abstract Background Arsenic contamination is widespread throughout the world and this toxic metalloid is known to cause cancers of organs such as liver, kidney, skin, and lung in human. In spite of a recent surge in arsenic related studies, we are still far from a comprehensive understanding of arsenic uptake, detoxification, and sequestration in plants. Crambe abyssinica, commonly known as 'abyssinian mustard', is a non-food, high biomass oil seed crop that is naturally tolerant to heavy metals. Moreover, it accumulates significantly higher levels of arsenic as compared to other species of the Brassicaceae family. Thus, C. abyssinica has great potential to be utilized as an ideal inedible crop for phytoremediation of heavy metals and metalloids. However, the mechanism of arsenic metabolism in higher plants, including C. abyssinica, remains elusive. Results To identify the differentially expressed transcripts and the pathways involved in arsenic metabolism and detoxification, C. abyssinica plants were subjected to arsenate stress and a PCR-Select Suppression Subtraction Hybridization (SSH approach was employed. A total of 105 differentially expressed subtracted cDNAs were sequenced which were found to represent 38 genes. Those genes encode proteins functioning as antioxidants, metal transporters, reductases, enzymes involved in the protein degradation pathway, and several novel uncharacterized proteins. The transcripts corresponding to the subtracted cDNAs showed strong upregulation by arsenate stress as confirmed by the semi-quantitative RT-PCR. Conclusions Our study revealed novel insights into the plant defense mechanisms and the regulation of genes and gene networks in response to arsenate toxicity. The differential expression of transcripts encoding glutathione-S-transferases, antioxidants, sulfur metabolism, heat-shock proteins, metal transporters, and enzymes in the ubiquitination pathway of protein degradation as well as several unknown

Expression profiling of Crambe abyssinica under arsenate stress identifies genes and gene networks involved in arsenic metabolism and detoxification

Science.gov (United States)

2010-01-01

Background Arsenic contamination is widespread throughout the world and this toxic metalloid is known to cause cancers of organs such as liver, kidney, skin, and lung in human. In spite of a recent surge in arsenic related studies, we are still far from a comprehensive understanding of arsenic uptake, detoxification, and sequestration in plants. Crambe abyssinica, commonly known as 'abyssinian mustard', is a non-food, high biomass oil seed crop that is naturally tolerant to heavy metals. Moreover, it accumulates significantly higher levels of arsenic as compared to other species of the Brassicaceae family. Thus, C. abyssinica has great potential to be utilized as an ideal inedible crop for phytoremediation of heavy metals and metalloids. However, the mechanism of arsenic metabolism in higher plants, including C. abyssinica, remains elusive. Results To identify the differentially expressed transcripts and the pathways involved in arsenic metabolism and detoxification, C. abyssinica plants were subjected to arsenate stress and a PCR-Select Suppression Subtraction Hybridization (SSH) approach was employed. A total of 105 differentially expressed subtracted cDNAs were sequenced which were found to represent 38 genes. Those genes encode proteins functioning as antioxidants, metal transporters, reductases, enzymes involved in the protein degradation pathway, and several novel uncharacterized proteins. The transcripts corresponding to the subtracted cDNAs showed strong upregulation by arsenate stress as confirmed by the semi-quantitative RT-PCR. Conclusions Our study revealed novel insights into the plant defense mechanisms and the regulation of genes and gene networks in response to arsenate toxicity. The differential expression of transcripts encoding glutathione-S-transferases, antioxidants, sulfur metabolism, heat-shock proteins, metal transporters, and enzymes in the ubiquitination pathway of protein degradation as well as several unknown novel proteins serve as

Graphene oxide/ferric hydroxide composites for efficient arsenate removal from drinking water

International Nuclear Information System (INIS)

Zhang Kai; Dwivedi, Vineet; Chi Chunyan; Wu Jishan

2010-01-01

A series of novel composites based on graphene oxide (GO) cross-linked with ferric hydroxide was developed for effective removal of arsenate from contaminated drinking water. GO, which was used as a supporting matrix here, was firstly treated with ferrous sulfate. Then, the ferrous compound cross-linked with GO was in situ oxidized to ferric compound by hydrogen peroxide, followed by treating with ammonium hydroxide. The morphology and composition of the composites were analyzed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The ferric hydroxide was found to be homogenously impregnated onto GO sheets in amorphous form. These composites were evaluated as absorbents for arsenate removal from contaminated drinking water. For the water with arsenate concentration at 51.14 ppm, more than 95% of arsenate was absorbed by composite GO-Fe-5 with an absorption capacity of 23.78 mg arsenate/g of composite. Effective arsenate removal occurred in a wide range of pH from 4 to 9. However, the efficiency of arsenate removal was decreased when pH was increased to higher than 8.

Embryotoxicity of arsenite and arsenate

International Nuclear Information System (INIS)

Lindgren, A.; Danielsson, R.G.; Dencker, L.; Vahter, M.

1984-01-01

The distribution of 74 As-labelled and arsenite in pregnant mice and a monkey has been studied by autoradiography and gamma counting of isolated tissues, and their in vitro toxicity to a chondrogenic system has been investigated. With both arsenic forms, given as single intravenous injections to the mother, the 74 As-arsenic appeared to pass the mouse placenta relatively freely and approximately to the same extent. The retention time in material tissues including the placenta was, however, around three times longer with arsenite than with arsenate. In early gestation, high activity was registered in the embryonic neuroepithelium, which correlates well with reported CNS malformations in rodents. In late gestation, the distribution pattern was more like that in the adults. Accumulation in skin and squamous epithelia of the upper gastrointestinal tract (oral cavity, oesophagus and oesophageal region of stomach) dominated the distribution pucture, especially at a long survival interval. Arsenate, but not arsenite, showed affinity for the calcified areas of the skeleton. A marmoset monkey in late gestation receiving arsenite showed a somewhat lower rate of placental transfer than the mice. Skin and liver had the highest concentrations (at 8 hrs), both in mother and foetuses. This species is known not to methylate arsenic, resulting in stronger binding and longer retention times of arsenic as compared with other species. The stronger binding in maternal tissues may possibly explain the lower rate of placental transfer. Arsenite was shown to inhibit cartilage formation in a chick limb bud mesenchymal spot culture system (ED50 approximately 5-10μM) while arsenate seemed to be without effect at concentrations up to 200 μM (highest tested). Arsenate, however, showed a potential of the arsenite toxicity. (author)

Comparison of arsenate and cadmium toxicity in a freshwater amphipod (Gammarus pulex)

International Nuclear Information System (INIS)

Vellinger, Céline; Parant, Marc; Rousselle, Philippe; Immel, Françoise

2012-01-01

Cadmium is largely documented on freshwater organisms while arsenic, especially arsenate, is rarely studied. The kinetic of the LC50s values for both metals was realized on Gammarus pulex. Physiological [i.e. metal concentration in body tissues, bioconcentration factor (BCF)] effects and behavioural responses (via pleopods beats) were investigated after 240-h exposure. Arsenate LC50 value was 100 fold higher than Cd-LC50 value after 240-h exposure, while concentrations in gammarids were similar for both metals at their respective LC50s. BCF decreased with increasing cadmium concentration while BCF remained stable with increasing arsenate concentration. Moreover, BCF was between 148 and 344 times lower for arsenate than cadmium. A significant hypoventilation was observed for cadmium concentrations exceeding or close to the 240h-LC50 Cd , while gammarids hyperventilated for the lowest arsenate concentrations and hypoventilated for the highest arsenate concentrations. We discussed the relationships between potential action mechanisms of these two metals and observed results. - Highlights: ► First study of arsenate toxicity in a Crustacean gammarid. ► Specific toxicological and behavioural responses to AsV and Cd contamination. ► Each metal led to specific-action mechanisms. ► Different energetic reallocation could explain specific behavioural responses. - This study brings to light the potential relationship between toxicological effects and behavioural responses of G. pulex exposed at both Cadmium and Arsenate.

Arsenate-induced maternal glucose intolerance and neural tube defects in a mouse model

International Nuclear Information System (INIS)

Hill, Denise S.; Wlodarczyk, Bogdan J.; Mitchell, Laura E.; Finnell, Richard H.

2009-01-01

Background: Epidemiological studies have linked environmental arsenic (As) exposure to increased type 2 diabetes risk. Periconceptional hyperglycemia is a significant risk factor for neural tube defects (NTDs), the second most common structural birth defect. A suspected teratogen, arsenic (As) induces NTDs in laboratory animals. Objectives: We investigated whether maternal glucose homeostasis disruption was responsible for arsenate-induced NTDs in a well-established dosing regimen used in studies of arsenic's teratogenicity in early neurodevelopment. Methods: We evaluated maternal intraperitoneal (IP) exposure to As 9.6 mg/kg (as sodium arsenate) in LM/Bc/Fnn mice for teratogenicity and disruption of maternal plasma glucose and insulin levels. Selected compounds (insulin pellet, sodium selenate (SS), N-acetyl cysteine (NAC), L-methionine (L-Met), N-tert-Butyl-α-phenylnitrone (PBN)) were investigated for their potential to mitigate arsenate's effects. Results: Arsenate caused significant glucose elevation during an IP glucose tolerance test (IPGTT). Insulin levels were not different between arsenate and control dams before (arsenate, 0.55 ng/dl; control, 0.48 ng/dl) or after glucose challenge (arsenate, 1.09 ng/dl; control, 0.81 ng/dl). HOMA-IR index was higher for arsenate (3.9) vs control (2.5) dams (p = 0.0260). Arsenate caused NTDs (100%, p < 0.0001). Insulin pellet and NAC were the most successful rescue agents, reducing NTD rates to 45% and 35%. Conclusions: IPGTT, insulin assay, and HOMA-IR results suggest a modest failure of glucose stimulated insulin secretion and insulin resistance characteristic of glucose intolerance. Insulin's success in preventing arsenate-induced NTDs provides evidence that these arsenate-induced NTDs are secondary to elevated maternal glucose. The NAC rescue, which did not restore maternal glucose or insulin levels, suggests oxidative disruption plays a role.

Adsorption of arsenate from aqueous solution by rice husk-based adsorbent

International Nuclear Information System (INIS)

Khan, Taimur; Chaudhuri, Malay

2013-01-01

Rice husk-based adsorbent (RHBA) was prepared by burning rice husk in a muffle furnace at 400°C for 4 h and adsorption of arsenate by the RHBA from aqueous solution was examined. Batch adsorption test showed that extent of arsenate adsorption depended on contact time and pH. Equilibrium adsorption was attained in 60 min, with maximum adsorption occurring at pH 7. Equilibrium adsorption data were well described by the Freundlich isotherm model. Freundlich constants K f and 1/n were 3.62 and 2, respectively. The RHBA is effective in the adsorption of arsenate from water and is a potentially suitable filter medium for removing arsenate from groundwater at wells or in households.

Thermochemical investigations on uranyl phosphates and arsenates

International Nuclear Information System (INIS)

Barten, H.

1986-01-01

Results are described of a study of the thermochemical stability of anhydrous phosphates and arsenates. The results of phase studies deal with compound formation and characterization, coexisting phases and limiting physical or chemical properties. The uranyl phosphates evolve oxygen at higher temperatures and the arsenates lose arsenic oxide vapour. These phenomena give the possibility to describe their thermodynamic stabilities. Thus oxygen pressures of uranyl phosphates have been measured using a static, non-isothermal method. Having made available the pure anhydrous compounds in the course of this investigation, molar thermodynamic quantities have been measured as well. These include standard enthalpies of formation from solution calorimetry and high-temperature heat-capacity functions derived from enthalpy increments measured. Some attention is given to compounds with uranium in valencies lower than six which have been met during the investigation. An evaluation is made of the thermodynamics of the compounds studied, to result in tabulized high-temperature thermodynamic functions. Relative stabilities within the systems are discussed and comparisons of the uranyl phosphates and the arsenates are made. (Auth.)

Pore-Water Carbonate and Phosphate As Predictors of Arsenate Toxicity in Soil.

Science.gov (United States)

Lamb, Dane T; Kader, Mohammed; Wang, Liang; Choppala, Girish; Rahman, Mohammad Mahmudur; Megharaj, Mallavarapu; Naidu, Ravi

2016-12-06

Phytotoxicity of inorganic contaminants is influenced by the presence of competing ions at the site of uptake. In this study, interaction of soil pore-water constituents with arsenate toxicity was investigated in cucumber (Cucumis sativa L) using 10 contrasting soils. Arsenate phytotoxicity was shown to be related to soluble carbonate and phosphate. The data indicated that dissolved phosphate and carbonate had an antagonistic impact on arsenate toxicity to cucumber. To predict arsenate phytotoxicity in soils with a diverse range of soil solution properties, both carbonate and phosphate were required. The relationship between arsenic and pore-water toxicity parameters was established initially using multiple regression. In addition, based on the relationship with carbonate and phosphate we successively applied a terrestrial biotic ligand-like model (BLM) including carbonate and phosphate. Estimated effective concentrations from the BLM-like parametrization were strongly correlated to measured arsenate values in pore-water (R 2 = 0.76, P soils.

Arsenates of rare-metals: electrometric investigations on praseodymium arsenates as a function of pH

Energy Technology Data Exchange (ETDEWEB)

Prasad, S [Paraiba Univ., Joao Pessoa (Brazil). Dept. de Engenharia Quimica

1982-01-01

The stoichiometry of the compounds formed by the interaction of praseodymium chloride and different alkali arsenates (meta, pyro and ortho) at specific pH levels - 7.2, 8.3 and 11.1 - was investigated by electrometric techniques involving pH measurements and potentiometric and conductometric titrations. The inflections and breaks in the titration curves provide evidence for the formation of three praseodymium arsenates having the molecular formulae Pr/sub 2/O/sub 3/.3 As/sub 2/O/sub 5/, 2Pr/sub 2/O/sub 3/.3As/sub 2/O/sub 5/ and Pr2O/sub 3/.As/sub 2/O/sub 5/ in the vicinity of pH 4.8, 5.8 and 7.0, respectively. Analysis of the compounds by conventional methods (gravimetric, as oxide, for praseodymium; iodometric for arsenic) substantiate the results of the electrometric study

Simultaneous sequestration of uranyl and arsenate at the goethite/water interface

International Nuclear Information System (INIS)

Fang Yuan; Yawen Cai; Shitong Yang; Zhiyong Liu; Lanhua Chen; Yue Lang; Shuao Wang; Xiangke Wang; Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Suzhou; North China Electric Power University, Beijing

2017-01-01

This study highlights the simultaneous sequestration of U(VI) and arsenate at the goethite/water interface. The uptake trends and speciation of these two components were related with molar arsenate/U(VI) ratio, solution pH, contact order and aging time. A metastable [UO_2(H_2AsO_4)_2·H_2O] was observed after 3 days and then this solid completely transformed into Na_2(UO_2AsO_4)_2·3H_2O after 7 days. The disodium ethylenediamine tetraacetate ligand gave rise to the complete dissolution of Na_2(UO_2AsO_4)_2·3H_2O phase and the release of U(VI) and arsenate back into the solution. The experimental findings facilitated us better comprehend the migration and fate of coexisting U(VI) and arsenate in the aquatic environment. (author)

Crystal structure and vibrational spectra of melaminium arsenate

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Anbalagan, G.; Marchewka, M. K.; Pawlus, K.; Kanagathara, N.

2015-01-01

The crystals of the new melaminium arsenate (MAS) [C3H7N6+ṡH2AsO4-] were obtained by the slow evaporation of an aqueous solution at room temperature. Single crystal X-ray diffraction analysis reveals that the crystal belongs to triclinic system with centro symmetric space group P-1. The crystals are built up from single protonated melaminium residues and single dissociated arsenate H2AsO4- anions. The protonated melaminium ring is almost planar. A combination of ionic and donor-acceptor hydrogen-bond interactions linking together the melaminium and arsenate residues forms a three-dimensional network. Vibrational spectroscopic analysis is reported on the basis of FT-IR and FT-Raman spectra recorded at room temperature. Hydrogen bonded network present in the crystal gives notable vibrational effect. DSC has also been performed for the crystal shows no phase transition in the studied temperature range (113-293 K).

Evaluation of ferrolysis in arsenate adsorption on the paddy soil derived from an Oxisol.

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Jiang, Jun; Dai, Zhaoxia; Sun, Rui; Zhao, Zhenjie; Dong, Ying; Hong, Zhineng; Xu, Renkou

2017-07-01

Iron oxides are dominant effective adsorbents for arsenate in iron oxide-rich variable charge soils. Oxisol-derived paddy soils undergo intensive ferrolysis, which results in high leaching and transformation of iron oxides. However, little information is available concerning the effect of ferrolysis on arsenate adsorption by paddy soil and parent Oxisol. In the present study, we examined the arsenate affinity of soils using arsenate adsorption/desorption isotherms, zeta potential, adsorption kinetics, pH effect and phosphate competition experiments. Results showed that ferrolysis in an alternating flooding-drying Oxisol-derived paddy soil resulted in a significant decrease of free iron oxides and increase of amorphous iron oxides in the surface and subsurface layers. There were more reactive sites exposed on amorphous than on crystalline iron oxides. Therefore, disproportionate ratios of arsenate adsorption capacities and contents of free iron oxides were observed in the studied Oxisols compared with paddy soils. The Gibbs free energy values corroborated that both electrostatic and non-electrostatic adsorption mechanisms contributed to the arsenate adsorption by bulk soils, and the kinetic adsorption data further suggested that the rate-limiting step was chemisorption. The zeta potential of soil colloids decreased after arsenate was adsorbed on the surfaces, forming inner-sphere complexes and thus transferring their negative charges to the soil particle surfaces. The adsorption/desorption isotherms showed that non-electrostatic adsorption was the main mechanism responsible for arsenate binding to the Oxisol and derived paddy soils, representing 91.42-94.65% of the adsorption capacities. Further studies revealed that arsenate adsorption was greatly inhibited by increasing suspension pH and incorporation of phosphate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rice-arsenate interactions in hydroponics: whole genome transcriptional analysis.

Science.gov (United States)

Norton, Gareth J; Lou-Hing, Daniel E; Meharg, Andrew A; Price, Adam H

2008-01-01

Rice (Oryza sativa) varieties that are arsenate-tolerant (Bala) and -sensitive (Azucena) were used to conduct a transcriptome analysis of the response of rice seedlings to sodium arsenate (AsV) in hydroponic solution. RNA extracted from the roots of three replicate experiments of plants grown for 1 week in phosphate-free nutrient with or without 13.3 muM AsV was used to challenge the Affymetrix (52K) GeneChip Rice Genome array. A total of 576 probe sets were significantly up-regulated at least 2-fold in both varieties, whereas 622 were down-regulated. Ontological classification is presented. As expected, a large number of transcription factors, stress proteins, and transporters demonstrated differential expression. Striking is the lack of response of classic oxidative stress-responsive genes or phytochelatin synthases/synthatases. However, the large number of responses from genes involved in glutathione synthesis, metabolism, and transport suggests that glutathione conjugation and arsenate methylation may be important biochemical responses to arsenate challenge. In this report, no attempt is made to dissect differences in the response of the tolerant and sensitive variety, but analysis in a companion article will link gene expression to the known tolerance loci available in the BalaxAzucena mapping population.

Rice–arsenate interactions in hydroponics: whole genome transcriptional analysis

Science.gov (United States)

Norton, Gareth J.; Lou-Hing, Daniel E.; Meharg, Andrew A.; Price, Adam H.

2008-01-01

Rice (Oryza sativa) varieties that are arsenate-tolerant (Bala) and -sensitive (Azucena) were used to conduct a transcriptome analysis of the response of rice seedlings to sodium arsenate (AsV) in hydroponic solution. RNA extracted from the roots of three replicate experiments of plants grown for 1 week in phosphate-free nutrient with or without 13.3 μM AsV was used to challenge the Affymetrix (52K) GeneChip Rice Genome array. A total of 576 probe sets were significantly up-regulated at least 2-fold in both varieties, whereas 622 were down-regulated. Ontological classification is presented. As expected, a large number of transcription factors, stress proteins, and transporters demonstrated differential expression. Striking is the lack of response of classic oxidative stress-responsive genes or phytochelatin synthases/synthatases. However, the large number of responses from genes involved in glutathione synthesis, metabolism, and transport suggests that glutathione conjugation and arsenate methylation may be important biochemical responses to arsenate challenge. In this report, no attempt is made to dissect differences in the response of the tolerant and sensitive variety, but analysis in a companion article will link gene expression to the known tolerance loci available in the Bala×Azucena mapping population. PMID:18453530

Efficient removal of chromate and arsenate from individual and mixed system by malachite nanoparticles

International Nuclear Information System (INIS)

Saikia, Jiban; Saha, Bedabrata; Das, Gopal

2011-01-01

Graphical abstract: Malachite nanoparticles of 100-150 nm, have been efficiently and for the first time used as an adsorbent for the removal of toxic arsenate and chromate in pH range 4-5. - Abstract: Malachite nanoparticles of 100-150 nm have been efficiently and for the first time used as an adsorbent for the removal of toxic arsenate and chromate. We report a high adsorption capacity for chromate and arsenate on malachite nanoparticle from both individual and mixed solution in pH ∼4-5. However, the adsorption efficiency decreases with the increase of solution pH. Batch studies revealed that initial pH, temperature, malachite nanoparticles dose and initial concentration of chromate and arsenate were important parameters for the adsorption process. Thermodynamic analysis showed that adsorption of chromate and arsenate on malachite nanoparticles is endothermic and spontaneous. The adsorption of these anions has also been investigated quantitatively with the help of adsorption kinetics, isotherm, and selectivity coefficient (K) analysis. The adsorption data for both chromate and arsenate were fitted well in Langmuir isotherm and preferentially followed the second order kinetics. The binding affinity of chromate is found to be slightly higher than arsenate in a competitive adsorption process which leads to the comparatively higher adsorption of chromate on malachite nanoparticles surface.

Coprecipitation of arsenate with metal oxides. 3. Nature, mineralogy, and reactivity of iron(III)-aluminum precipitates.

Science.gov (United States)

Violante, Antonio; Pigna, Massimo; Del Gaudio, Stefania; Cozzolino, Vincenza; Banerjee, Dipanjan

2009-03-01

Coprecipitation involving arsenic with aluminum or iron has been studied because this technique is considered particularly efficient for removal of this toxic element from polluted waters. Coprecipitation of arsenic with mixed iron-aluminum solutions has received scant attention. In this work we studied (i)the mineralogy, surface properties, and chemical composition of mixed iron-aluminum oxides formed at initial Fe/Al molar ratio of 1.0 in the absence or presence of arsenate [As/ Fe+Al molar ratio (R) of 0, 0.01, or 0.1] and at pH 4.0, 7.0, and 10.0 and aged for 30 and 210 days at 50 degrees C and (ii) the removal of arsenate from the coprecipitates after addition of phosphate. The amounts of short-range ordered precipitates (ferrihydrite, aluminous ferrihydrite and/or poorly crystalline boehmite) were greater than those found in iron and aluminum systems (studied in previous works), due to the capacity of both aluminum and arsenate to retard or inhibitthe transformation of the initially formed precipitates into well-crystallized oxides (gibbsite, bayerite, and hematite). As a consequence, the surface areas of the iron-aluminum oxides formed in the absence or presence of arsenate were usually much larger than those of aluminum or iron oxides formed under the same conditions. Arsenate was found to be associated mainly into short-range ordered materials. Chemical composition of all samples was affected by pH, initial R, and aging. Phosphate sorption was facilitated by the presence of short-range ordered materials, mainly those richer in aluminum, but was inhibited by arsenate present in the samples. The quantities of arsenate replaced by phosphate, expressed as percentages of its total amount present in the samples, were particularly low, ranging from 10% to 26%. A comparison of the desorption of arsenate by phosphate from aluminum-arsenate and iron-arsenate (studied in previous works) and iron-aluminum-arsenate coprecipitates evidenced that phosphate has a greater

Studies on the lanthanum arsenate ion-exchanger: preparation, physicochemical properties and applications

International Nuclear Information System (INIS)

Mukherjee, A.K.; Mandal, S.K.

1984-01-01

The cation-exchange behaviour of lanthanum arsenate has been studied. This paper reports the preparation and physicochemical properties of the exchanger. Its analytical utility is compared with that of other arsenate exchangers. Some practical analytical applications are described. (author)

Efficient removal of chromate and arsenate from individual and mixed system by malachite nanoparticles.

Science.gov (United States)

Saikia, Jiban; Saha, Bedabrata; Das, Gopal

2011-02-15

Malachite nanoparticles of 100-150 nm have been efficiently and for the first time used as an adsorbent for the removal of toxic arsenate and chromate. We report a high adsorption capacity for chromate and arsenate on malachite nanoparticle from both individual and mixed solution in pH ∼4-5. However, the adsorption efficiency decreases with the increase of solution pH. Batch studies revealed that initial pH, temperature, malachite nanoparticles dose and initial concentration of chromate and arsenate were important parameters for the adsorption process. Thermodynamic analysis showed that adsorption of chromate and arsenate on malachite nanoparticles is endothermic and spontaneous. The adsorption of these anions has also been investigated quantitatively with the help of adsorption kinetics, isotherm, and selectivity coefficient (K) analysis. The adsorption data for both chromate and arsenate were fitted well in Langmuir isotherm and preferentially followed the second order kinetics. The binding affinity of chromate is found to be slightly higher than arsenate in a competitive adsorption process which leads to the comparatively higher adsorption of chromate on malachite nanoparticles surface. Copyright © 2010 Elsevier B.V. All rights reserved.

Formation of iron (hydr)oxides during the abiotic oxidation of Fe(II) in the presence of arsenate.

Science.gov (United States)

Song, Jia; Jia, Shao-Yi; Yu, Bo; Wu, Song-Hai; Han, Xu

2015-08-30

Abiotic oxidation of Fe(II) is a common pathway in the formation of Fe (hydr)oxides under natural conditions, however, little is known regarding the presence of arsenate on this process. In hence, the effect of arsenate on the precipitation of Fe (hydr)oxides during the oxidation of Fe(II) is investigated. Formation of arsenic-containing Fe (hydr)oxides is constrained by pH and molar ratios of As:Fe during the oxidation Fe(II). At pH 6.0, arsenate inhibits the formation of lepidocrocite and goethite, while favors the formation of ferric arsenate with the increasing As:Fe ratio. At pH 7.0, arsenate promotes the formation of hollow-structured Fe (hydr)oxides containing arsenate, as the As:Fe ratio reaches 0.07. Arsenate effectively inhibits the formation of magnetite at pH 8.0 even at As:Fe ratio of 0.01, while favors the formation of lepidocrocite and green rust, which can be latterly degenerated and replaced by ferric arsenate with the increasing As:Fe ratio. This study indicates that arsenate and low pH value favor the slow growth of dense-structured Fe (hydr)oxides like spherical ferric arsenate. With the rapid oxidation rate of Fe(II) at high pH, ferric (hydr)oxides prefer to precipitate in the formation of loose-structured Fe (hydr)oxides like lepidocrocite and green rust. Copyright © 2015 Elsevier B.V. All rights reserved.

Adsorption of arsenate on Cu/Mg/Fe/La layered double hydroxide from aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Guo, Yanwei [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Zhu, Zhiliang, E-mail: zzl@tongji.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Qiu, Yanling [Key Laboratory of Yangtze River Water Environment, Ministry of Education, Tongji University, Shanghai 200092 (China); Zhao, Jianfu [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China)

2012-11-15

Highlights: Black-Right-Pointing-Pointer A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized. Black-Right-Pointing-Pointer The average pore size of the materials with about 16 nm indicated that the mesoporous structures existed in the Cu/Mg/Fe/La-LDHs. Black-Right-Pointing-Pointer The adsorption capacity of As(V) increased with the increment of La{sup 3+} content in the LDH. Black-Right-Pointing-Pointer The maximum adsorption capacity of the synthesized Cu/Mg/Fe/La-LDH for arsenate was 43.5 mg/g. - Abstract: A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized and used for the removal of arsenate from aqueous solutions. The purpose of incorporation of La{sup 3+} into LDHs was tried to enhance the uptake efficiency of arsenate and broaden the application field of LDHs functional materials. Effects of various physico-chemical factors such as solution pH, adsorbent dosage, contact time and initial arsenate concentrations on the adsorption of arsenate onto Cu/Mg/Fe/La-LDH were investigated. Results showed that the removal efficiency of arsenate increased with the increment of the lanthanum content in Cu/Mg/Fe/La-LDH adsorbents, and the optimized lanthanum content was 20% of the total trivalent metals composition (Fe{sup 3+} and La{sup 3+}). The adsorption isotherms can be well described by Langmuir equation, and the adsorption kinetics of arsenate followed the pseudo-second-order kinetic model. Coexistent ions such as HPO{sub 4}{sup 2-}, CO{sub 3}{sup 2-}, SO{sub 4}{sup 2-}, Cl{sup -} and NO{sub 3}{sup -} exhibited obvious competition with arsenate for the adsorption on Cu/Mg/Fe/La-LDH. The solution pH significantly affected the removal efficiency, which was closely related to the change of arsenate species distribution under different pH conditions. The predominant adsorption mechanism can be mainly attributed to the processes including ion exchange and layer ligand exchange.

Adsorption of arsenate on Cu/Mg/Fe/La layered double hydroxide from aqueous solutions

International Nuclear Information System (INIS)

Guo, Yanwei; Zhu, Zhiliang; Qiu, Yanling; Zhao, Jianfu

2012-01-01

Highlights: ► A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized. ► The average pore size of the materials with about 16 nm indicated that the mesoporous structures existed in the Cu/Mg/Fe/La-LDHs. ► The adsorption capacity of As(V) increased with the increment of La 3+ content in the LDH. ► The maximum adsorption capacity of the synthesized Cu/Mg/Fe/La-LDH for arsenate was 43.5 mg/g. - Abstract: A novel layered double hydroxide containing lanthanum (Cu/Mg/Fe/La-LDH) has been synthesized and used for the removal of arsenate from aqueous solutions. The purpose of incorporation of La 3+ into LDHs was tried to enhance the uptake efficiency of arsenate and broaden the application field of LDHs functional materials. Effects of various physico-chemical factors such as solution pH, adsorbent dosage, contact time and initial arsenate concentrations on the adsorption of arsenate onto Cu/Mg/Fe/La-LDH were investigated. Results showed that the removal efficiency of arsenate increased with the increment of the lanthanum content in Cu/Mg/Fe/La-LDH adsorbents, and the optimized lanthanum content was 20% of the total trivalent metals composition (Fe 3+ and La 3+ ). The adsorption isotherms can be well described by Langmuir equation, and the adsorption kinetics of arsenate followed the pseudo-second-order kinetic model. Coexistent ions such as HPO 4 2− , CO 3 2− , SO 4 2− , Cl − and NO 3 − exhibited obvious competition with arsenate for the adsorption on Cu/Mg/Fe/La-LDH. The solution pH significantly affected the removal efficiency, which was closely related to the change of arsenate species distribution under different pH conditions. The predominant adsorption mechanism can be mainly attributed to the processes including ion exchange and layer ligand exchange.

Amino-functionalized MCM-41 and MCM-48 for the removal of chromate and arsenate.

Science.gov (United States)

Benhamou, A; Basly, J P; Baudu, M; Derriche, Z; Hamacha, R

2013-08-15

The aim of the present work was to investigate the efficiency of three amino-functionalized (hexadecylamine, dodecylamine, and dimethyldodecylamine) mesoporous silicas (MCM-41 and MCM-48) toward the adsorption of arsenate and chromate. Hexadecylamine-functionalized materials were characterized; BET surface areas, pore volumes, and sizes decreased with the functionalization, whereas XRD patterns show that the hexagonal structure of MCM-41 and the cubic structure of MCM-48 were not modified. The zeta potential decreases with pH and the highest arsenate and chromate removal was observed at the lowest pHs. Adsorption of chromium and arsenate was significantly enhanced after functionalization and amino-functionalized MCM-41 adsorb larger amounts of arsenate when compared to expanded MCM-48 materials. Chromate sorption capacities increased with the chain length and the larger capacities were obtained with hexadecylamine-functionalized mesoporous silicas. Mesoporous silicas modified by dimethyldodecylamine exhibited the higher arsenate sorption capacities. Copyright © 2013 Elsevier Inc. All rights reserved.

Adsorption of arsenate on soils. Part 1: Laboratory batch experiments using 16 Chinese soils with different physiochemical properties

International Nuclear Information System (INIS)

Jiang Wei; Zhang Shuzhen; Shan Xiaoquan; Feng Muhua; Zhu Yongguan; McLaren, Ron G.

2005-01-01

Laboratory batch experiments were carried out to study the adsorption of arsenate on 16 Chinese soils with different physicochemical properties. Wide differences in arsenate adsorption were observed, and the Jiangxi and Hubei soils were more effective sorbents for arsenate than other soils. The Langmuir one-surface and two-surface equations were used to model the arsenate adsorption data. Except for the Jiangxi and Hubei soils, the Langmuir one-surface equation gave reasonably good fits to the arsenate adsorption data. However, the Langmuir two-surface equation generally provided a better fit than the Langmuir one-surface equation. For soils with relative high organic matter (OM), dissolved organic carbon (DOC) or extractable phosphate, the Langmuir one-surface and two-surface equations described the adsorption isotherms similarly. In contrast, for soils with relatively low contents of OM, DOC or extractable phosphate, the Langmuir two-surface equation gave the better fit to the arsenate adsorption data. - The Langmuir two-surface equation fits arsenate adsorption onto soils

Arsenate tolerance in Silene paradoxa does not rely on phytochelatin-dependent sequestration

International Nuclear Information System (INIS)

Arnetoli, Miluscia; Vooijs, Riet; Bookum, Wilma ten; Galardi, Francesca; Gonnelli, Cristina; Gabbrielli, Roberto; Schat, Henk; Verkleij, Jos A.C.

2008-01-01

Arsenate tolerance, As accumulation and As-induced phytochelatin accumulation were compared in populations of Silene paradoxa, one from a mine site enriched in As, Cu and Zn, the other from an uncontaminated site. The mine population was significantly more arsenate-tolerant. Arsenate uptake and root-to-shoot transport were slightly but significantly higher in the non-mine plants. The difference in uptake was quantitatively insufficient to explain the difference in tolerance between the populations. As accumulation in the roots was similar in both populations, but the mine plants accumulated much less phytochelatins than the non-mine plants. The mean phytochelatin chain length, however, was higher in the mine population, possibly due to a constitutively lower cellular glutathione level. It is argued that the mine plants must possess an arsenic detoxification mechanism other than arsenate reduction and subsequent phytochelatin-based sequestration. This alternative mechanism might explain at least some part of the superior tolerance in the mine plants. - Neither decreased uptake nor phytochelatins seem to play a role in the As tolerance in Silene paradoxa

Absorption and translocation of arsenate arsenic by coffee plants

Energy Technology Data Exchange (ETDEWEB)

Pereira, J F; Yamaguchi, S

1964-01-01

Studies on arsenate arsenic absorption and translocation in coffee plants were carried out using arsenic-77 applied either to leaves or to roots through the nutrient solution. The youngest leaves were unable to export arsenic and only an acropetal movement in the transpiration stream was observed. From the second pair of leaves, it moved into the growing leaves. From the fourth pair it moved downward through the stem and into the roots. Roots absorbed high amounts of arsenate once absorbed it moved via the xylem of the transpiration stream into the leaves. 7 references, 2 figures.

X-ray graphical and thermodynamical study of mercury arsenates

International Nuclear Information System (INIS)

Makitova, G. Zh.; Mustafin, E. S.; Kasenov, B. K.

1999-01-01

Purposes of the work are both determination of lattice parameters on the base of X-ray graphical data and experimental study of thermal conduction dependence of mercury arsenates Hg(AsO 3 ) 2 and Hg 3 (AsO 4 ) 2 . In this work for the first time the parameters of elementary cell thermal conduction in the range 298.15-625 K were determined. Formation of equilibrium contents of mercury arsenates was confirmed by X-ray phase analysis conducted on DRON-2,0 unit under Cu K - radiation. Curves of thermal-differential analysis show, that Hg(AsO 3 ) 2 and Hg 3 (AsO 4 ) 2 melting incongruently, relatively at 725 and 790 grad C. Displaying of X-ray- grammars of examined compounds have been conducted by homology method. On the base the displaying parameter of lattice crystallization were determined. Further arsenates were exposed to calorimetric research for determination of its thermal conduction. It is shown, that Hg 3 (AsO 4 ) 2 thermal conduction has maximum at 448 K and then it value is go down at 473 K and then smoothly increasing. It was supposed, such behavior is related with second kind phase transformation

RiArsB and RiMT-11: Two novel genes induced by arsenate in arbuscular mycorrhiza.

Science.gov (United States)

Maldonado-Mendoza, Ignacio E; Harrison, Maria J

Plants associated with arbuscular mycorrhizal fungi (AMF) increase their tolerance to arsenic-polluted soils. This study aims to investigate the genes involved in the AMF molecular response to arsenic pollution. Genes encoding proteins involved in arsenic metabolism were identified and their expression assessed by PCR or RT-qPCR. The As-inducible gene GiArsA (R. irregularis ABC ATPase component of the ArsAB arsenite efflux pump) and two new genes, an arsenate/arsenite permease component of ArsAB (RiArsB) and a methyltransferase type 11 (RiMT-11) were induced when arsenate was added to two-compartment in vitro monoxenic cultures of R. irregularis-transformed carrot roots. RiArsB and RiMT-11 expression in extraradical hyphae in response to arsenate displayed maximum induction 4-6 h after addition of 350 μM arsenate. Their expression was also detected in colonized root tissues grown in pots, or in the root-fungus compartment of two-compartment in vitro systems. We used a Medicago truncatula double mutant (mtpt4/mtpt8) to demonstrate that RiMT-11 and RiArsB transcripts accumulate in response to the addition of arsenate but not in response to phosphate. These results suggest that these genes respond to arsenate addition regardless of non-functional Pi symbiotic transport, and that RiMT-11 may be involved in arsenate detoxification by methylation in AMF-colonized tissues. Copyright © 2017 British Mycological Society. All rights reserved.

Focused Ion Beam Analysis of Banana Peel and Its Application for Arsenate Ion Removal

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Jamil R. Memon

2015-06-01

Full Text Available Banana peel, a common fruit waste, has been investigated for its ability to remove arsenate ions from ground water as a function of pH, contact time, and initial metal ion concentration. Focused ion beam (FIB analysis revealed the internal morphology of the banana peels. Arsenate ions were entered into micropores of banana peel. pH was seen to have no effect on the sorption process. Retained species were eluted using 5 mL of 2 M H2SO4. The kinetics of sorption were observed to follow the pseudo first order rate equation. The sorption data followed Freundlich and D-R isotherms. The energy value obtained from the D-R isotherms indicated that the sorption was physical in nature for arsenate species. Our study has shown that banana peel has the ability to remove arsenate species from ground water samples.

Focused ion beam analysis of banana peel and its application for arsenate ion removal

International Nuclear Information System (INIS)

Memon, J.R.

2015-01-01

Banana peel, a common fruit waste, has been investigated for its ability to remove arsenate ions from ground water as a function of pH, contact time, and initial metal ion concentration. Focused ion beam (FIB) analysis revealed the internal morphology of the banana peels. Arsenate ions were entered into micropores of banana peel. pH was seen to have no effect on the sorption process. Retained species were eluted using 5 mL of 2 M H/sub 2/SO/sub 4/. The kinetics of sorption were observed to follow the pseudo first order rate equation. The sorption data followed Freundlich and D-R isotherms. The energy value obtained from the D-R isotherms indicated that the sorption was physical in nature for arsenate species. Our study has shown that banana peel has the ability to remove arsenate species from ground water samples. (author)

Competitive adsorption of arsenate and phosphate onto calcite; experimental results and modeling with CCM and CD-MUSIC

DEFF Research Database (Denmark)

Sø, Helle Ugilt; Postma, Dieke; Jakobsen, Rasmus

2012-01-01

The competitive adsorption of arsenate and phosphate onto calcite was studied in batch experiments using calcite-equilibrated solutions. The solutions had circum-neutral pH (7–8.3) and covered a wide span in the activity of Ca2+ and View the MathML source. The results show that the adsorption...... that adsorption of arsenate onto calcite is of minor importance in most groundwater aquifers, as phosphate is often present at concentration levels sufficient to significantly reduce arsenate adsorption. The CD-MUSIC model for calcite was used successfully to model adsorption of arsenate and phosphate separately...

Possible Roles of Plant Sulfurtransferases in Detoxification of Cyanide, Reactive Oxygen Species, Selected Heavy Metals and Arsenate

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Parvin Most

2015-01-01

Full Text Available Plants and animals have evolved various potential mechanisms to surmount the adverse effects of heavy metal toxicity. Plants possess low molecular weight compounds containing sulfhydryl groups (-SH that actively react with toxic metals. For instance, glutathione (γ-Glu-Cys-Gly is a sulfur-containing tripeptide thiol and a substrate of cysteine-rich phytochelatins (γ-Glu-Cys2–11-Gly (PCs. Phytochelatins react with heavy metal ions by glutathione S-transferase in the cytosol and afterwards they are sequestered into the vacuole for degradation. Furthermore, heavy metals induce reactive oxygen species (ROS, which directly or indirectly influence metabolic processes. Reduced glutathione (GSH attributes as an antioxidant and participates to control ROS during stress. Maintenance of the GSH/GSSG ratio is important for cellular redox balance, which is crucial for the survival of the plants. In this context, sulfurtransferases (Str, also called rhodaneses, comprise a group of enzymes widely distributed in all phyla, paving the way for the transfer of a sulfur atom from suitable sulfur donors to nucleophilic sulfur acceptors, at least in vitro. The best characterized in vitro reaction is the transfer of a sulfane sulfur atom from thiosulfate to cyanide, leading to the formation of sulfite and thiocyanate. Plants as well as other organisms have multi-protein families (MPF of Str. Despite the presence of Str activities in many living organisms, their physiological role has not been clarified unambiguously. In mammals, these proteins are involved in the elimination of cyanide released from cyanogenic compounds. However, their ubiquity suggests additional physiological functions. Furthermore, it is speculated that a member of the Str family acts as arsenate reductase (AR and is involved in arsenate detoxification. In summary, the role of Str in detoxification processes is still not well understood but seems to be a major function in the organism.

Characterization of the respiratory chain of Helicobacter pylori

DEFF Research Database (Denmark)

Chen, M; Andersen, L P; Zhai, L

1999-01-01

reductase was inhibited by antimycin, implying the presence of a classical pathway from complex II to complex III in this bacterium. The presence of NADH-fumarate reductase (FRD) was demonstrated in H. pylori and fumarate could reduce H2O2 production from NADH, indicating fumarate to be an endogenous......-dependent respiration was significantly stronger than NADH-dependent respiration, indicating that this is a major respiratory electron donor in H. pylori. Fumarate and malonate exhibited a concentration-dependent inhibitory effect on the activity of succinate dehydrogenase. The activity of succinate-cytochrome c...

Lead, arsenic, and copper content of crops grown on lead arsenate-treated and untreated soils

Energy Technology Data Exchange (ETDEWEB)

Chisholm, D

1972-01-01

Increased lead and arsenic concentrations in the surface soil (0-15 cm), resulting from applications of lead arsenate (PbHAs0/sub 1/), increased both lead and arsenic levels in crops grown on treated plots. The lead levels in some crops approached or exceeded the Canadian residue tolerance of 2.0 ppM. Lead arsenate soil treatments did not affect copper absorption by crops. On areas such as old orchard land contaminated with lead arsenate residues it may be advisable to ascertain crops, and also to determine the lead affinity and arsenic sensitivity of the plants to be grown.

Fabrication and evolution of multilayer silver nanofilms for surface-enhanced Raman scattering sensing of arsenate

Directory of Open Access Journals (Sweden)

Li Jinwei

2011-01-01

Full Text Available Abstract Surface-enhanced Raman scattering (SERS has recently been investigated extensively for chemical and biomolecular sensing. Multilayer silver (Ag nanofilms deposited on glass slides by a simple electroless deposition process have been fabricated as active substrates (Ag/GL substrates for arsenate SERS sensing. The nanostructures and layer characteristics of the multilayer Ag films could be tuned by varying the concentrations of reactants (AgNO3/BuNH2 and reaction time. A Ag nanoparticles (AgNPs double-layer was formed by directly reducing Ag+ ions on the glass surfaces, while a top layer (3rd-layer of Ag dendrites was deposited on the double-layer by self-assembling AgNPs or AgNPs aggregates which had already formed in the suspension. The SERS spectra of arsenate showed that characteristic SERS bands of arsenate appear at approximately 780 and 420 cm-1, and the former possesses higher SERS intensity. By comparing the peak heights of the approximately 780 cm-1 band of the SERS spectra, the optimal Ag/GL substrate has been obtained for the most sensitive SERS sensing of arsenate. Using this optimal substrate, the limit of detection (LOD of arsenate was determined to be approximately 5 μg·l-1.

An arsenate-reducing and alkane-metabolizing novel bacterium, Rhizobium arsenicireducens sp. nov., isolated from arsenic-rich groundwater.

Science.gov (United States)

Mohapatra, Balaram; Sarkar, Angana; Joshi, Swati; Chatterjee, Atrayee; Kazy, Sufia Khannam; Maiti, Mrinal Kumar; Satyanarayana, Tulasi; Sar, Pinaki

2017-03-01

A novel arsenic (As)-resistant, arsenate-respiring, alkane-metabolizing bacterium KAs 5-22 T , isolated from As-rich groundwater of West Bengal was characterized by physiological and genomic properties. Cells of strain KAs 5-22 T were Gram-stain-negative, rod-shaped, motile, and facultative anaerobic. Growth occurred at optimum of pH 6.0-7.0, temperature 30 °C. 16S rRNA gene affiliated the strain KAs 5-22 T to the genus Rhizobium showing maximum similarity (98.4 %) with the type strain of Rhizobium naphthalenivorans TSY03b T followed by (98.0 % similarity) Rhizobium selenitireducens B1 T . The genomic G + C content was 59.4 mol%, and DNA-DNA relatedness with its closest phylogenetic neighbors was 50.2 %. Chemotaxonomy indicated UQ-10 as the major quinone; phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol as major polar lipids; C 16:0 , C 17:0 , 2-OH C 10:0 , 3-OH C 16:0 , and unresolved C 18:1 ɷ7C/ɷ9C as predominant fatty acids. The cells were found to reduce O 2 , As 5+ , NO 3 - , SO 4 2- and Fe 3+ as alternate electron acceptors. The strain's ability to metabolize dodecane or other alkanes as sole carbon source using As 5+ as terminal electron acceptor was supported by the presence of genes encoding benzyl succinate synthase (bssA like) and molybdopterin-binding site (mopB) of As 5+ respiratory reductase (arrA). Differential phenotypic, chemotaxonomic, genotypic as well as physiological properties revealed that the strain KAs 5-22 T is separated from its nearest recognized Rhizobium species. On the basis of the data presented, strain KAs 5-22 T is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium arsenicireducens sp. nov. is proposed as type strain (=LMG 28795 T =MTCC 12115 T ).

Inhibition of NADH-ubiquinone reductase activity by N,N'-dicyclohexylcarbodiimide and correlation of this inhibition with the occurrence of energy-coupling site 1 in various organisms

International Nuclear Information System (INIS)

Yagi, T.

1987-01-01

The NADH-ubiquinone reductase activity of the respiratory chains of several organisms was inhibited by the carboxyl-modifying reagent N,N'-dicyclohexylcarbodiimide (DCCD). This inhibition correlated with the presence of an energy-transducing site in this segment of the respiratory chain. Where the NADH-quinone reductase segment involved an energy-coupling site (e.g., in bovine heart and rat liver mitochondria, and in Paracoccus denitrificans, Escherichia coli, and Thermus thermophilus HB-8 membranes), DCCD acted as an inhibitor of ubiquinone reduction by NADH. By contrast, where energy-coupling site 1 was absent (e.g., in Saccharomyces cerevisiae mitochondria and BacilLus subtilis membranes), there was no inhibition of NADH-ubiquinone reductase activity by DCCD. In the bovine and P. denitrificans systems, DCCD inhibition was pseudo first order with respect to incubation time, and reaction order with respect to inhibitor concentration was close to unity, indicating that inhibition resulted from the binding of one inhibitor molecule per active unit of NADH-ubiquinone reductase. In the bovine NADH-ubiquinone reductase complex (complex I), [ 14 C]DCCD was preferentially incorporated into two subunits of molecular weight 49,000 and 29,000. The time course of labeling of the 29,000 molecular weight subunit with [ 14 C]DCCD paralleled the time course of inhibition of NADH-ubiquinone reductase activity

Crystallization and preliminary crystallographic characterization of LmACR2, an arsenate/antimonate reductase from Leishmania major

Energy Technology Data Exchange (ETDEWEB)

Bisacchi, Davide [Bioinformatics and Structural Proteomics, IST-National Cancer Research Institute, Genova (Italy); Zhou, Yao; Rosen, Barry P.; Mukhopadhyay, Rita [Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, Michigan (United States); Bordo, Domenico, E-mail: domenico.bordo@istge.it [Bioinformatics and Structural Proteomics, IST-National Cancer Research Institute, Genova (Italy)

2006-10-01

LmACR2 from L. major is the first rhodanese-like enzyme directly involved in the reduction of arsenate and antimonate to be crystallized. Diffraction data have been collected to 1.99 Å resolution using synchrotron X-rays. Arsenic is present in the biosphere owing either to the presence of pesticides and herbicides used in agricultural and industrial activities or to leaching from geological formations. The health effects of prolonged exposure to arsenic can be devastating and may lead to various forms of cancer. Antimony(V), which is chemically very similar to arsenic, is used instead in the treatment of leishmaniasis, an infection caused by the protozoan parasite Leishmania sp.; the reduction of pentavalent antimony contained in the drug Pentostam to the active trivalent form arises from the presence in the Leishmania genome of a gene, LmACR2, coding for the protein LmACR2 (14.5 kDa, 127 amino acids) that displays weak but significant sequence similarity to the catalytic domain of Cdc25 phosphatase and to rhodanese enzymes. For structural characterization, LmACR2 was overexpressed, purified to homogeneity and crystallized in a trigonal space group (P321 or P3{sub 1}21/P3{sub 2}21). The protein crystallized in two distinct trigonal crystal forms, with unit-cell parameters a = b = 111.0, c = 86.1 Å and a = b = 111.0, c = 175.6 Å, respectively. At a synchrotron beamline, the diffraction pattern extended to a resolution limit of 1.99 Å.

Crystallization and preliminary crystallographic characterization of LmACR2, an arsenate/antimonate reductase from Leishmania major

International Nuclear Information System (INIS)

Bisacchi, Davide; Zhou, Yao; Rosen, Barry P.; Mukhopadhyay, Rita; Bordo, Domenico

2006-01-01

LmACR2 from L. major is the first rhodanese-like enzyme directly involved in the reduction of arsenate and antimonate to be crystallized. Diffraction data have been collected to 1.99 Å resolution using synchrotron X-rays. Arsenic is present in the biosphere owing either to the presence of pesticides and herbicides used in agricultural and industrial activities or to leaching from geological formations. The health effects of prolonged exposure to arsenic can be devastating and may lead to various forms of cancer. Antimony(V), which is chemically very similar to arsenic, is used instead in the treatment of leishmaniasis, an infection caused by the protozoan parasite Leishmania sp.; the reduction of pentavalent antimony contained in the drug Pentostam to the active trivalent form arises from the presence in the Leishmania genome of a gene, LmACR2, coding for the protein LmACR2 (14.5 kDa, 127 amino acids) that displays weak but significant sequence similarity to the catalytic domain of Cdc25 phosphatase and to rhodanese enzymes. For structural characterization, LmACR2 was overexpressed, purified to homogeneity and crystallized in a trigonal space group (P321 or P3 1 21/P3 2 21). The protein crystallized in two distinct trigonal crystal forms, with unit-cell parameters a = b = 111.0, c = 86.1 Å and a = b = 111.0, c = 175.6 Å, respectively. At a synchrotron beamline, the diffraction pattern extended to a resolution limit of 1.99 Å

Ketopantoyl lactone reductase is a conjugated polyketone reductase.

Science.gov (United States)

Hata, H; Shimizu, S; Hattori, S; Yamada, H

1989-03-01

Ketopantoyl lactone reductase (EC 1.1.1.168) of Saccharomyces cerevisiae was found to catalyze the reduction of a variety of natural and unnatural conjugated polyketone compounds and quinones, such as isatin, ninhydrin, camphorquinone and beta-naphthoquinone in the presence of NADPH. 5-Bromoisatin is the best substrate for the enzyme (Km = 3.1 mM; Vmax = 650 mumol/min/mg). The enzyme is inhibited by quercetin, and several polyketones. These results suggest that ketopantoyl lactone reductase is a carbonyl reductase which specifically catalyzes the reduction of conjugated polyketones.

Arsenate removal by layered double hydroxides embedded into spherical polymer beads: Batch and column studies.

Science.gov (United States)

Nhat Ha, Ho Nguyen; Kim Phuong, Nguyen Thi; Boi An, Tran; Mai Tho, Nguyen Thi; Ngoc Thang, Tran; Quang Minh, Bui; Van Du, Cao

2016-01-01

In this study, the performance of poly(layered double hydroxides) [poly(LDHs)] beads as an adsorbent for arsenate removal from aqueous solution was investigated. The poly(LDHs) beads were prepared by immobilizing LDHs into spherical alginate/polyvinyl alcohol (PVA)-glutaraldehyde beads (spherical polymer beads). Batch adsorption studies were conducted to assess the effect of contact time, solution pH, initial arsenate concentrations and co-existing anions on arsenate removal performance. The potential reuse of these poly(LDHs) beads was also investigated. Approximately 79.1 to 91.2% of arsenic was removed from an arsenate solution (50 mg As L(-1)) by poly(LDHs). The adsorption data were well described by the pseudo-second-order kinetics model and the Langmuir isotherm model, and the adsorption capacities of these poly(LDHs) beads at pH 8 were from 1.64 to 1.73 mg As g(-1), as calculated from the Langmuir adsorption isotherm. The adsorption ability of the poly(LDHs) beads decreased by approximately 5-6% after 5 adsorption-desorption cycles. Phosphates markedly decreased arsenate removal. The effect of co-existing anions on the adsorption capacity declined in the following order: HPO4 (2-) > HCO3 (-) > SO4 (2-) > Cl(-). A fixed-bed column study was conducted with real-life arsenic-containing water. The breakthrough time was found to be from 7 to 10 h. Under optimized conditions, the poly(LDHs) removed more than 82% of total arsenic. The results obtained in this study will be useful for further extending the adsorbents to the field scale or for designing pilot plants in future studies. From the viewpoint of environmental friendliness, the poly(LDHs) beads are a potential cost-effective adsorbent for arsenate removal in water treatment.

Adsorption of arsenate on soils. Part 2: Modeling the relationship between adsorption capacity and soil physiochemical properties using 16 Chinese soils

International Nuclear Information System (INIS)

Jiang Wei; Zhang, Shuzhen; Shan Xiaoquan; Feng Muhua; Zhu Yongguan; McLaren, Ron G.

2005-01-01

An attempt has been made to elucidate the effects of soil properties on arsenate adsorption by modeling the relationships between adsorption capacity and the properties of 16 Chinese soils. The model produced was validated against three Australian and three American soils. The results showed that nearly 93.8% of the variability in arsenate adsorption on the low-energy surface could be described by citrate-dithionite extractable Fe (Fe CD ), clay content, organic matter content (OM) and dissolved organic carbon (DOC); nearly 87.6% of the variability in arsenate adsorption on the high-energy surface could be described by Fe CD , DOC and total arsenic in soils. Fe CD exhibited the most important positive influence on arsenate adsorption. Oxalate extractable Al (Al OX ), citrate-dithionite extractable Al (Al CD ), extractable P and soil pH appeared relatively unimportant for adsorption of arsenate by soils. - Citrate-dithionite extractable Fe has the most important positive influence on arsenate adsorption on soils

Arsenate impact on the metabolite profile, production and arsenic loading of xylem sap in cucumbers (Cucumis sativus L.

Directory of Open Access Journals (Sweden)

Kalle eUroic

2012-04-01

Full Text Available Arsenic uptake and translocation studies on xylem sap focus generally on the concentration and speciation of arsenic in the xylem. Arsenic impact on the xylem sap metabolite profile and its production during short term exposure has not been reported in detail. To investigate this, cucumbers were grown hydroponically and arsenate (AsV and DMA were used for plant treatment for 24 h. Total arsenic and arsenic speciation in xylem sap was analysed including a metabolite profiling under arsenate stress. Produced xylem sap was quantified and absolute arsenic transported was determined. AsV exposure has a significant impact on the metabolite profile of xylem sap. Four m/z values corresponding to four compounds were up regulated, one compound down regulated by arsenate exposure. The compound down regulated was identified to be isoleucine. Furthermore, arsenate has a significant influence on sap production, leading to a reduction of up to 96 % sap production when plants are exposed to 1000 μg kg-1 arsenate. No difference to control plants was observed when plants were exposed to 1000 μg kg-1 DMA. Absolute arsenic amount in xylem sap was the lowest at high arsenate exposure. These results show that AsV has a significant impact on the production and metabolite profile of xylem sap. The physiological importance of isoleucine needs further attention.

Uptake and biotransformation of arsenate in the lichen Hypogymnia physodes (L.) Nyl

Energy Technology Data Exchange (ETDEWEB)

Mrak, Tanja [Department of Environmental Sciences, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Slejkovec, Zdenka [Department of Environmental Sciences, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)], E-mail: zdenka.slejkovec@ijs.si; Jeran, Zvonka; Jacimovic, Radojko [Department of Environmental Sciences, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Kastelec, Damijana [Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana (Slovenia)

2008-01-15

The uptake and metabolism of arsenate, As(V), as a function of time and concentration were examined in the lichen Hypogymnia physodes (L.) Nyl. Lichen thalli were exposed to As(V) in the form of a solution. Exponential uptake of As(V) from 4 {mu}g mL{sup -1} As(V) solution was accompanied by constant arsenite, As(III), excretion back into the solution. Arsenate taken up into the lichens from 0, 0.1, 1, 10 {mu}g mL{sup -1} As(V) solutions was partially transformed into As(III), dimethylarsinic acid (DMA) and (mono)methylarsonic acid (MA). 48 h after exposure, the main arsenic compound in the lichens was DMA in 0.1, As(III) in 1 and As(V) in 10 {mu}g mL{sup -1} treatment. The proportion of methylated arsenic compounds decreased with increasing arsenate concentration in the exposure solution. These results suggest that at least two types of As(V) detoxification exist in lichens; arsenite excretion and methylation. - Lichens are able to metabolize the inorganic arsenic taken up.

Exogenous proline enhances the sensitivity of Tobacco BY-2 cells to arsenate.

Science.gov (United States)

Nahar, Mst Nur-E-Nazmun; Islam, Mohammad Muzahidul; Hoque, Md Anamul; Yonezawa, Anna; Prodhan, Md Yeasin; Nakamura, Toshiyuki; Nakamura, Yoshimasa; Munemasa, Shintaro; Murata, Yoshiyuki

2017-09-01

Arsenic causes physiological and structural disorders in plants. Proline is accumulated as a compatible solute in plants under various stress conditions and mitigates stresses. Here, we investigated the effects of exogenous proline on tobacco Bright Yellow-2 (BY-2) cultured cells under [Formula: see text] stress. Arsenate did not inhibit BY-2 cell growth at 40 and 50 μM but did it at 60 μM. Proline at 0.5 to 10 mM did not affect the cell growth but delayed it at 20 mM. At 40 μM [Formula: see text], neither 0.5 mM nor 1 mM proline affected the cell growth but 10 mM proline inhibited it. In the presence of [Formula: see text], 10 mM proline increased the number of Evans Blue-stained (dead) cells and decreased the number of total cells. Together, our results suggest that exogenous proline does not alleviate arsenate toxicity but enhances the sensitivity of BY-2 cells to arsenate.

Uptake and biotransformation of arsenate in the lichen Hypogymnia physodes (L.) Nyl

International Nuclear Information System (INIS)

Mrak, Tanja; Slejkovec, Zdenka; Jeran, Zvonka; Jacimovic, Radojko; Kastelec, Damijana

2008-01-01

The uptake and metabolism of arsenate, As(V), as a function of time and concentration were examined in the lichen Hypogymnia physodes (L.) Nyl. Lichen thalli were exposed to As(V) in the form of a solution. Exponential uptake of As(V) from 4 μg mL -1 As(V) solution was accompanied by constant arsenite, As(III), excretion back into the solution. Arsenate taken up into the lichens from 0, 0.1, 1, 10 μg mL -1 As(V) solutions was partially transformed into As(III), dimethylarsinic acid (DMA) and (mono)methylarsonic acid (MA). 48 h after exposure, the main arsenic compound in the lichens was DMA in 0.1, As(III) in 1 and As(V) in 10 μg mL -1 treatment. The proportion of methylated arsenic compounds decreased with increasing arsenate concentration in the exposure solution. These results suggest that at least two types of As(V) detoxification exist in lichens; arsenite excretion and methylation. - Lichens are able to metabolize the inorganic arsenic taken up

Sodium meta-arsenate for pH-metric determination of rare earth elements

Energy Technology Data Exchange (ETDEWEB)

Prasad, S [Paraiba Univ. (Brazil). Centro de Ciencias e Tecnologia, Dept. de Engenharia Quimica

1981-01-01

An accurate and rapid electrometric method for the determination of praseodymium and thorium as their meta-arsenates has been investigated. It consists in titrating praseodymium chloride and thorium nitrate solutions pH-metrically against a standard solution of sodium meta-arsenate, using a wide range glass electrode in conjunction with S.C.E. A marked change in pH is observed at the end-point corresponding to the precipitation of Pr(AsO/sub 3/)/sub 3/ and Th/sub 3/(AsO/sub 3/)/sub 4/ in the neighbourhood of pH 4.8 and 4.2, respectively. The curves have a regular form and a pronounced maximum in dpH/dV occurs at the end-point. The accuracy and reproducibility of the results have been found to be excellent even at low concentrations (5x10sup(-4)M) of the reactants. pH titration offers a simple, rapid and accurate method for the determination of praseodymium and thorium as their meta-arsenates. Similar titrations were also performed for estimation of samarium but they failed to provide any dependable results.

Equilibriums of sorption of impurities of 3 d - cations by inorganic sorbents from phosphate and arsenate solutions

International Nuclear Information System (INIS)

Filatova, L.N.; Kurdyumova, T.N.; Bagrov, V.M.; Blyum, G.Z.

1986-01-01

Present article is devoted to equilibriums of sorption of impurities of 3 d - cations by inorganic sorbents from phosphate and arsenate solutions. Equilibriums of sorption of microquantities of iron, scandium, zink, copper, cobalt and manganese by inorganic sorbents on the basis of titanium and aluminium oxides from phosphate and arsenate solutions are studied. The influence of structural and chemical properties of matrix on sorption properties of oxides in phosphate and arsenate solutions is studied as well. It is defined that in concentrated solutions the sorption value of trace contaminant depends on a character of cation of alkaline metal.

RNA-seq analyses reveal insights into the function of respiratory nitrate reductase of the diazotroph Herbaspirillum seropedicae.

Science.gov (United States)

Bonato, Paloma; Batista, Marcelo B; Camilios-Neto, Doumit; Pankievicz, Vânia C S; Tadra-Sfeir, Michelle Z; Monteiro, Rose Adele; Pedrosa, Fabio O; Souza, Emanuel M; Chubatsu, Leda S; Wassem, Roseli; Rigo, Liu Un

2016-09-01

Herbaspirillum seropedicae is a nitrogen-fixing β-proteobacterium that associates with roots of gramineous plants. In silico analyses revealed that H. seropedicae genome has genes encoding a putative respiratory (NAR) and an assimilatory nitrate reductase (NAS). To date, little is known about nitrate metabolism in H. seropedicae, and, as this bacterium cannot respire nitrate, the function of NAR remains unknown. This study aimed to investigate the function of NAR in H. seropedicae and how it metabolizes nitrate in a low aerated-condition. RNA-seq transcriptional profiling in the presence of nitrate allowed us to pinpoint genes important for nitrate metabolism in H. seropedicae, including nitrate transporters and regulatory proteins. Additionally, both RNA-seq data and physiological characterization of a mutant in the catalytic subunit of NAR (narG mutant) showed that NAR is not required for nitrate assimilation but is required for: (i) production of high levels of nitrite, (ii) production of NO and (iii) dissipation of redox power, which in turn lead to an increase in carbon consumption. In addition, wheat plants showed an increase in shoot dry weight only when inoculated with H. seropedicae wild type, but not with the narG mutant, suggesting that NAR is important to H. seropedicae-wheat interaction. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Sorption and desorption of arsenate and arsenite on calcite

DEFF Research Database (Denmark)

Sø, Helle Ugilt; Postma, Diederik Jan; Jakobsen, Rasmus

2008-01-01

The adsorption and desorption of arsenate (As(V)) and arsenite (As(111)) oil calcite was investigated in a series of batch experiments in calcite-equilibrated solutions. The solutions covered a broad range of pH, alkalinity, calcium concentration and ionic strength. The initial arsenic...

Arsenite-oxidizing and arsenate-reducing bacteria associated with arsenic-rich groundwater in Taiwan

Science.gov (United States)

Liao, Vivian Hsiu-Chuan; Chu, Yu-Ju; Su, Yu-Chen; Hsiao, Sung-Yun; Wei, Chia-Cheng; Liu, Chen-Wuing; Liao, Chung-Min; Shen, Wei-Chiang; Chang, Fi-John

2011-04-01

Drinking highly arsenic-contaminated groundwater is a likely cause of blackfoot disease in Taiwan, but microorganisms that potentially control arsenic mobility in the subsurface remain unstudied. The objective of this study was to investigate the relevant arsenite-oxidizing and arsenate-reducing microbial community that exists in highly arsenic-contaminated groundwater in Taiwan. We cultured and identified arsenic-transforming bacteria, analyzed arsenic resistance and transformation, and determined the presence of genetic markers for arsenic transformation. In total, 11 arsenic-transforming bacterial strains with different colony morphologies and varying arsenic transformation abilities were isolated, including 10 facultative anaerobic arsenate-reducing bacteria and one strictly aerobic arsenite-oxidizing bacterium. All of the isolates exhibited high levels of arsenic resistance with minimum inhibitory concentrations of arsenic ranging from 2 to 200 mM. Strain AR-11 was able to rapidly oxidize arsenite to arsenate at concentrations relevant to environmental groundwater samples without the addition of any electron donors or acceptors. We provide evidence that arsenic-reduction activity may be conferred by the ars operon(s) that were not amplified by the designed primers currently in use. The 16S rRNA sequence analysis grouped the isolates into the following genera: Pseudomonas, Bacillus, Psychrobacter, Vibrio, Citrobacter, Enterobacter, and Bosea. Among these genera, we present the first report of the genus Psychrobacter being involved in arsenic reduction. Our results further support the hypothesis that bacteria capable of either oxidizing arsenite or reducing arsenate coexist and are ubiquitous in arsenic-contaminated groundwater.

Potential Remobilization of Toxic Anions during Reduction of Arsenated and Chromated Schwertmannite by the Dissimilatory Fe(III)-Reducing Bacterium Acidiphilium cryptum JF-5

International Nuclear Information System (INIS)

Regenspurg, Simona; Goessner, Anita; Peiffer, Stefan; Kuesel, Kirsten

2002-01-01

Schwertmannite, an iron(III)-oxyhydroxysulfate formed in acidic mining-impacted stream or lake waters often contaminated with toxic elements like arsenate or chromate, is able to incorporate high amounts of these oxyanions. Detoxification of the water might be achieved if precipitated arsenated or chromated schwertmannite is fixed in the sediment. However, under reduced conditions, reductive dissolution of iron oxides mediated by the activity of Fe(III)-reducing bacteria might mobilize arsenate and chromate again. In this study, the reduction of synthesized arsenated or chromated schwertmannite by the acidophilic Fe(III)-reducer Acidiphilium cryptum JF-5, isolated from an acidic mining-impacted sediment, was investigated. In TSB medium at pH 2.7 with glucose as electron donor, A. cryptum JF-5 reduced about 10% of the total Fe(III) present in pure synthetic schwertmannite but only 5% of Fe(III) present in arsenated schwertmannite. In contrast to sulfate that was released during the reductive dissolution of pure schwertmannite, arsenate was not released during the reduction of arsenated schwertmannite probably due to the high surface complexation constant of arsenate and Fe(III). In medium containing chromated schwertmannite, no Fe(II) was formed, and no glucose was consumed indicating that chromate might have been toxic to cells of A. cryptum JF-5. Both As(V) or Cr(VI) could not be utilized as electron acceptor by A. cryptum JF-5. A comparison between autoclaved (121 o C for 20 min) and non-autoclaved schwertmannite samples demonstrated that nearly 100%of the bound sulfate was released during heating, and FTIR spectra indicated a transformation of schwertmannite to goethite. This structural change was not observed with autoclaved arsenated or chromated schwertmannite. These results suggest that the mobility of arsenate and chromate is not enhanced by the activity of acidophilic Fe(III)-reducing bacteria in mining-impacted sediments. In contrast, the presence of

Arsenate Removal: Comparison of FSM-16 with Low Cost Modified Rice Husk

International Nuclear Information System (INIS)

Daifullah, A.A.M.

2004-01-01

The recently discovered meso porous molecular sieve FSM-16 was tested as an absorbent for arsenic (V) sorption from aqueous solutions. Its adsorption behavior was evaluated and compared with a low cost sorbent prepared from available agroresidue, rice husk, (boiled with 5% KOH followed by 10 % HCl). Factors affecting sorption of arsenate ions by the two sorbents (e.g., porosity, surface area of the sorbent, equilibrium time, adsorption rate, ph and temperature) were studied using ICP-MS for analysis. The data of adsorption of the two systems were described according to the S-Langmuir type according to the initial slope. The monolayer coverage was 92 and 68 mg/g for FSM-16 and modified rice husk (MRH),respectively, due to the silica content of the former is higher than the latter. The thermodynamic parameters were evaluated and indicated that this adsorption is endothermic process.It was found that the adsorptive capacity for arsenate using MRH represents 75% of that FSM-16. Therefore, the MRH is useful in the removal of arsenate ions due to its low cost, availability, and its good efficiency in this application and no need to be regenerated

The binding sites on human heme oxygenase-1 for cytochrome p450 reductase and biliverdin reductase.

Science.gov (United States)

Wang, Jinling; de Montellano, Paul R Ortiz

2003-05-30

Human heme oxygenase-1 (hHO-1) catalyzes the NADPH-cytochrome P450 reductase-dependent oxidation of heme to biliverdin, CO, and free iron. The biliverdin is subsequently reduced to bilirubin by biliverdin reductase. Earlier kinetic studies suggested that biliverdin reductase facilitates the release of biliverdin from hHO-1 (Liu, Y., and Ortiz de Montellano, P. R. (2000) J. Biol. Chem. 275, 5297-5307). We have investigated the binding of P450 reductase and biliverdin reductase to truncated, soluble hHO-1 by fluorescence resonance energy transfer and site-specific mutagenesis. P450 reductase and biliverdin reductase bind to truncated hHO-1 with Kd = 0.4 +/- 0.1 and 0.2 +/- 0.1 microm, respectively. FRET experiments indicate that biliverdin reductase and P450 reductase compete for binding to truncated hHO-1. Mutation of surface ionic residues shows that hHO-1 residues Lys18, Lys22, Lys179, Arg183, Arg198, Glu19, Glu127, and Glu190 contribute to the binding of cytochrome P450 reductase. The mutagenesis results and a computational analysis of the protein surfaces partially define the binding site for P450 reductase. An overlapping binding site including Lys18, Lys22, Lys179, Arg183, and Arg185 is similarly defined for biliverdin reductase. These results confirm the binding of biliverdin reductase to hHO-1 and define binding sites of the two reductases.

Arsenic triggers the nitric oxide (NO) and S-nitrosoglutathione (GSNO) metabolism in Arabidopsis

International Nuclear Information System (INIS)

Leterrier, Marina; Airaki, Morad; Palma, José M.; Chaki, Mounira; Barroso, Juan B.; Corpas, Francisco J.

2012-01-01

Environmental contamination by arsenic constitutes a problem in many countries, and its accumulation in food crops may pose health complications for humans. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are involved at various levels in the mechanism of responding to environmental stress in higher plants. Using Arabidopsis seedlings exposed to different arsenate concentrations, physiological and biochemical parameters were analyzed to determine the status of ROS and RNS metabolisms. Arsenate provoked a significant reduction in growth parameters and an increase in lipid oxidation. These changes were accompanied by an alteration in antioxidative enzymes and the nitric oxide (NO) metabolism, with a significant increase in NO content, S-nitrosoglutathione reductase (GSNOR) activity and protein tyrosine nitration as well as a concomitant reduction in glutathione and S-nitrosoglutathione (GSNO) content. Our results indicate that 500 μM arsenate (AsV) causes nitro-oxidative stress in Arabidopsis, being the glutathione reductase and the GSNOR activities clearly affected. - Highlights: ► In Arabidopsis, arsenate provokes damages in the membrane integrity of root cells. ► As induces an oxidative stress according to an increase in lipid oxidation. ► NO content and protein tyrosine nitration increases under arsenate stress. ► Arsenate provokes a reduction of GSH, GSSG and GSNO content. ► Arsenate induces a nitro-oxidative stress in Arabidopsis. - Arsenic stress affects nitric oxide (NO) and glutathione (GSH) metabolism which provokes a nitro-oxidative stress.

Photoinduced Oxidation of Arsenite to Arsenate on Ferrihydrite

Energy Technology Data Exchange (ETDEWEB)

N Bhandari; R Reeder; D Strongin

2011-12-31

The photochemistry of an aqueous suspension of the iron oxyhydroxide, ferrihydrite, in the presence of arsenite has been investigated using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray absorption near edge structure (XANES), and solution phase analysis. Both ATR-FTIR and XANES show that the exposure of ferrihydrite to arsenite in the dark leads to no change in the As oxidation state, but the exposure of this arsenite-bearing surface, which is in contact with pH 5 water, to light leads to the conversion of the majority of the adsorbed arsenite to the As(V) bearing species, arsenate. Analysis of the solution phase shows that ferrous iron is released into solution during the oxidation of arsenite. The photochemical reaction, however, shows the characteristics of a self-terminating reaction in that there is a significant suppression of this redox chemistry before 10% of the total iron making up the ferrihydrite partitions into solution as ferrous iron. The self-terminating behavior exhibited by this photochemical arsenite/ferrihydrite system is likely due to the passivation of the ferrihydrite surface by the strongly bound arsenate product.

Mitochondrial fumarate reductase as a target of chemotherapy: from parasites to cancer cells.

Science.gov (United States)

Sakai, Chika; Tomitsuka, Eriko; Esumi, Hiroyasu; Harada, Shigeharu; Kita, Kiyoshi

2012-05-01

Recent research on respiratory chain of the parasitic helminth, Ascaris suum has shown that the mitochondrial NADH-fumarate reductase system (fumarate respiration), which is composed of complex I (NADH-rhodoquinone reductase), rhodoquinone and complex II (rhodoquinol-fumarate reductase) plays an important role in the anaerobic energy metabolism of adult parasites inhabiting hosts. The enzymes in these parasite-specific pathways are potential target for chemotherapy. We isolated a novel compound, nafuredin, from Aspergillus niger, which inhibits NADH-fumarate reductase in helminth mitochondria at nM order. It competes for the quinone-binding site in complex I and shows high selective toxicity to the helminth enzyme. Moreover, nafuredin exerts anthelmintic activity against Haemonchus contortus in in vivo trials with sheep indicating that mitochondrial complex I is a promising target for chemotherapy. In addition to complex I, complex II is a good target because its catalytic direction is reverse of succinate-ubiquionone reductase in the host complex II. Furthermore, we found atpenin and flutolanil strongly and specifically inhibit mitochondrial complex II. Interestingly, fumarate respiration was found not only in the parasites but also in some types of human cancer cells. Analysis of the mitochondria from the cancer cells identified an anthelminthic as a specific inhibitor of the fumarate respiration. Role of isoforms of human complex II in the hypoxic condition of cancer cells and fetal tissues is a challenge. This article is part of a Special Issue entitled Biochemistry of Mitochondria, Life and Intervention 2010. Copyright © 2011 Elsevier B.V. All rights reserved.

Effects of arsenic on nitrate metabolism in arsenic hyperaccumulating and non-hyperaccumulating ferns

Energy Technology Data Exchange (ETDEWEB)

Singh, Nandita [Soil and Water Science Department, University of Florida, Gainesville, Fl 32611-0290 (United States); Eco-Auditing group, National Botanical Research Institute, Rana Pratap Marg, Lucknow 226 001 (India); Ma, Lena Q., E-mail: lqma@ufl.ed [Soil and Water Science Department, University of Florida, Gainesville, Fl 32611-0290 (United States); Vu, Joseph C. [Chemistry Research Unit, CMAVE, USDA-ARS, Gainesville, FL 32608-1069 and Agronomy Department, University of Florida, Gainesville, FL 32611-0500 (United States); Raj, Anshita [Eco-Auditing group, National Botanical Research Institute, Rana Pratap Marg, Lucknow 226 001 (India)

2009-08-15

This study investigated the effects of arsenic on the in vitro activities of the enzymes (nitrate reductase and nitrite reductase) involved in nitrate metabolism in the roots, rhizomes, and fronds of four-month old Pteris vittata (arsenic - hyperaccumulator) and Pteris ensiformis (non-arsenic--hyperaccumulator) plants. The arsenic treatments (0, 150, and 300 muM as sodium arsenate) in hydroponics had adverse effects on the root and frond dry weights, and this effect was more evident in P. ensiformis than in P. vittata. Nitrate reductase and nitrite reductase activities of arsenate-treated plants were reduced more in P. ensiformis than in P. vittata. This effect was accompanied by similar decreases in tissue NO{sub 3}{sup -} concentrations. Therefore, this decrease is interpreted as being indirect, i.e., the consequence of the reduced NO{sub 3}{sup -} uptake and translocation in the plants. The study shows the difference in the tolerance level of the two Pteris species with varying sensitivity to arsenic. - Arsenic reduced the activity of nitrate and nitrite reductase more in Pteris ensiformis than Pteris vittata.

PIXE study on absorption of arsenate and arsenite by arsenic hyperaccumulating fern (Pteris vittata)

International Nuclear Information System (INIS)

Yamazaki, H.; Ishii, K.; Matsuyama, S.

2008-01-01

Pytoremediation using an arsenic hyperaccumulator, Petris vittata L., has generated an increasing interest worldwide due to both environmentally sound and cost effectiveness. However the mechanism of arsenic accumulation by this fern is not clear at this time. This study examined the uptake of arsenate (As(V)) and arsenite (As(III)) by a hydroponic culture of Pteris vittata using both in-air submilli-PIXE for different parts of the fern and in-air micro-PIXE for the tissue cells. These PIXE analysis systems used 3 MeV proton beams from a 4.5-MV single-ended Dynamitron accelerator at Tohoku University, Japan. The fern took up both arsenate and arsenite from hydroponic solutions which were spiked with 50 mg of arsenic per litter. Final amount of arsenic accumulation in the fern is 1,500 mg per kg (wet weight) of the plant biomass in arsenite treatment and 1,100 mg per kg in arsenate treatment. Arsenic accumulation was not observed at the root parts of the ferns. The in-vivo mapping of elements by submilli-PIXE analyses on the fern laminas showed the arsenic accumulation in the edges of a pinna. The micro-PIXE analyses revealed arsenic maps homogeneously distributed in cells of the lamina, stem and rhizome of the fern. These results indicate that arsenic, both arsenate and arsenite in a contaminated medium are translocated quickly from roots to fronds of Pteris vittata, and distributes homogeneously into tissue cells of the fern laminas. (author)

Phosphate and arsenate removal efficiency by thermostable ferritin enzyme from Pyrococcus furiosus using radioisotopes

KAUST Repository

Sevcenco, Ana-Maria

2015-03-13

Oxo-anion binding properties of the thermostable enzyme ferritin from Pyrococcus furiosus were characterized with radiography. Radioisotopes 32P and 76As present as oxoanions were used to measure the extent and the rate of their absorption by the ferritin. Thermostable ferritin proved to be an excellent system for rapid phosphate and arsenate removal from aqueous solutions down to residual concentrations at the picomolar level. These very low concentrations make thermostable ferritin a potential tool to considerably mitigate industrial biofouling by phosphate limitation or to remove arsenate from drinking water.

Behavior of Eucalyptus urophylla and Eucalyptus citriodora Seedlings Grown in Soil Contaminated by Arsenate

Directory of Open Access Journals (Sweden)

Roseli Freire Melo

2016-01-01

Full Text Available ABSTRACT Persistent areas of tailings and deposits from coal and gold mining may present high levels of arsenic (As, mainly in the arsenate form, endangering the environment and human health. The establishment of vegetation cover is a key step to reclaiming these environments. Thus, this study aimed to evaluate the potential of Eucalyptus urophylla and E. citriodora seedlings for use in phytoremediation programs of arsenate-contaminated areas. Soil samples were incubated at increasing rates (0, 50, 100, 200 and 400 mg dm-3 of arsenic (arsenate form, using Na2HAsO4 for 15 days. The seedlings were produced in a substrate (vermiculite + sawdust and were transplanted to the pots with soil three months after seed germination. The values of plant height and diameter were taken during transplanting and 30, 60 and 90 days after transplanting. In the last evaluation, the total leaf area and biomass of shoots and roots were also determined. The values of available As in soil which caused a 50 % dry matter reduction (TS50%, the As translocation index (TI from the roots to the shoot of the plants, and its bioconcentration factor (BF were also calculated. Higher levels of arsenate in the soil significantly reduced the dry matter production of roots and shoots and the height of both species, most notably in E. urophylla plants. The highest levels of As were found in the root, with higher values for E. citriodora (ranging from 253.86 to 400 mg dm-3. The TI and BF were also reduced with As doses, but the values found in E. citriodora were significantly higher than in E. urophylla. E. citriodora plants presented a higher capacity to tolerate As and translocate it to the shoot than E. urophylla. Although these species cannot be considered as hyperaccumulators of As, E. citriodora presented the potential to be used in phytoremediation programs in arsenate-contaminated areas due to the long-term growth period of this species.

Differential Pair Distribution Function Study of the Structure of Arsenate Adsorbed on Nanocrystalline [gamma]-Alumina

Energy Technology Data Exchange (ETDEWEB)

Li, Wei; Harrington, Richard; Tang, Yuanzhi; Kubicki, James D.; Aryanpour, Masoud; Reeder, Richard J.; Parise, John B.; Phillips, Brian L. (SBU); (Penn)

2012-03-15

Structural information is important for understanding surface adsorption mechanisms of contaminants on metal (hydr)oxides. In this work, a novel technique was employed to study the interfacial structure of arsenate oxyanions adsorbed on {gamma}-alumina nanoparticles, namely, differential pair distribution function (d-PDF) analysis of synchrotron X-ray total scattering. The d-PDF is the difference of properly normalized PDFs obtained for samples with and without arsenate adsorbed, otherwise identically prepared. The real space pattern contains information on atomic pair correlations between adsorbed arsenate and the atoms on {gamma}-alumina surface (Al, O, etc.). PDF results on the arsenate adsorption sample on {gamma}-alumina prepared at 1 mM As concentration and pH 5 revealed two peaks at 1.66 {angstrom} and 3.09 {angstrom}, corresponding to As-O and As-Al atomic pair correlations. This observation is consistent with those measured by extended X-ray absorption fine structure (EXAFS) spectroscopy, which suggests a first shell of As-O at 1.69 {+-} 0.01 {angstrom} with a coordination number of 4 and a second shell of As-Al at 3.13 {+-} 0.04 {angstrom} with a coordination number of 2. These results are in agreement with a bidentate binuclear coordination environment to the octahedral Al of {gamma}-alumina as predicted by density functional theory (DFT) calculation.

Differential pair distribution function study of the structure of arsenate adsorbed on nanocrystalline γ-alumina.

Science.gov (United States)

Li, Wei; Harrington, Richard; Tang, Yuanzhi; Kubicki, James D; Aryanpour, Masoud; Reeder, Richard J; Parise, John B; Phillips, Brian L

2011-11-15

Structural information is important for understanding surface adsorption mechanisms of contaminants on metal (hydr)oxides. In this work, a novel technique was employed to study the interfacial structure of arsenate oxyanions adsorbed on γ-alumina nanoparticles, namely, differential pair distribution function (d-PDF) analysis of synchrotron X-ray total scattering. The d-PDF is the difference of properly normalized PDFs obtained for samples with and without arsenate adsorbed, otherwise identically prepared. The real space pattern contains information on atomic pair correlations between adsorbed arsenate and the atoms on γ-alumina surface (Al, O, etc.). PDF results on the arsenate adsorption sample on γ-alumina prepared at 1 mM As concentration and pH 5 revealed two peaks at 1.66 Å and 3.09 Å, corresponding to As-O and As-Al atomic pair correlations. This observation is consistent with those measured by extended X-ray absorption fine structure (EXAFS) spectroscopy, which suggests a first shell of As-O at 1.69 ± 0.01 Å with a coordination number of ~4 and a second shell of As-Al at ~3.13 ± 0.04 Å with a coordination number of ~2. These results are in agreement with a bidentate binuclear coordination environment to the octahedral Al of γ-alumina as predicted by density functional theory (DFT) calculation.

Facile synthesis of size-tunable gold nanoparticles by pomegranate (Punica granatum) leaf extract: Applications in arsenate sensing

Energy Technology Data Exchange (ETDEWEB)

Rao, Ashit; Mahajan, Ketakee; Bankar, Ashok [Institute of Bioinformatics and Biotechnology, University of Pune, Pune 411007 (India); Srikanth, Rapole [Proteomics Laboratory, National Centre for Cell Science, Pune 411007 (India); Kumar, Ameeta Ravi [Institute of Bioinformatics and Biotechnology, University of Pune, Pune 411007 (India); Gosavi, Suresh, E-mail: swg@physics.unipune.ac.in [Department of Physics, University of Pune, Pune 411007 (India); Centre for Sensor Studies, University of Pune, Pune 411007 (India); Zinjarde, Smita, E-mail: smita@unipune.ac.in [Institute of Bioinformatics and Biotechnology, University of Pune, Pune 411007 (India); Centre for Sensor Studies, University of Pune, Pune 411007 (India)

2013-03-15

Highlights: ► Pomegranate leaf extracts mediated rapid gold nanoparticle (AuNP) synthesis. ► The phyto-inspired AuNPs were size-tuned and characterized. ► The reducing and capping agents in the extract were identified. ► The nanoparticles reacted specifically with arsenate (V) ions. - Abstract: When pomegranate leaf extracts were incubated with chloroauric acid (HAuCl{sub 4}), gold nanoparticles (AuNPs) were synthesized. These were characterized by a variety of techniques. With an increasing content of the leaf extract, a gradual decrease in size and an increase in monodispersity were observed. Transmission electron microscope (TEM) images showed that the phyto-fabricated AuNPs were surrounded by an amorphous layer. Gallic acid in the extract mediated the reduction and a natural decapeptide capped the nanostructures. Blocking of thiol groups in the decapeptide cysteine residues caused the nanoparticles to aggregate. On interaction with arsenate (V) ions, the UV–vis spectra of the nanoparticles showed a decrease in intensity and a red-shift. Energy dispersive spectra confirmed the presence of arsenate associated with the AuNPs. Thus, by using these AuNPs, a method for sensing the toxic arsenate ions could be developed.

Facile synthesis of size-tunable gold nanoparticles by pomegranate (Punica granatum) leaf extract: Applications in arsenate sensing

International Nuclear Information System (INIS)

Rao, Ashit; Mahajan, Ketakee; Bankar, Ashok; Srikanth, Rapole; Kumar, Ameeta Ravi; Gosavi, Suresh; Zinjarde, Smita

2013-01-01

Highlights: ► Pomegranate leaf extracts mediated rapid gold nanoparticle (AuNP) synthesis. ► The phyto-inspired AuNPs were size-tuned and characterized. ► The reducing and capping agents in the extract were identified. ► The nanoparticles reacted specifically with arsenate (V) ions. - Abstract: When pomegranate leaf extracts were incubated with chloroauric acid (HAuCl 4 ), gold nanoparticles (AuNPs) were synthesized. These were characterized by a variety of techniques. With an increasing content of the leaf extract, a gradual decrease in size and an increase in monodispersity were observed. Transmission electron microscope (TEM) images showed that the phyto-fabricated AuNPs were surrounded by an amorphous layer. Gallic acid in the extract mediated the reduction and a natural decapeptide capped the nanostructures. Blocking of thiol groups in the decapeptide cysteine residues caused the nanoparticles to aggregate. On interaction with arsenate (V) ions, the UV–vis spectra of the nanoparticles showed a decrease in intensity and a red-shift. Energy dispersive spectra confirmed the presence of arsenate associated with the AuNPs. Thus, by using these AuNPs, a method for sensing the toxic arsenate ions could be developed

Removal of arsenate by ferrihydrite via surface complexation and surface precipitation

Energy Technology Data Exchange (ETDEWEB)

Jiang, Xiuli [Department of Environment Engineering, College of the Environment and Ecology, and The Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, Xiamen University, Xiamen (China); Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, and The Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen (China); Peng, Changjun; Fu, Dun; Chen, Zheng [Department of Environment Engineering, College of the Environment and Ecology, and The Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, Xiamen University, Xiamen (China); Shen, Liang [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, and The Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen (China); Li, Qingbiao [Department of Environment Engineering, College of the Environment and Ecology, and The Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, Xiamen University, Xiamen (China); Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, and The Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen (China); Ouyang, Tong, E-mail: yz3t@xmu.edu.cn [Department of Environment Engineering, College of the Environment and Ecology, and The Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, Xiamen University, Xiamen (China); Wang, Yuanpeng, E-mail: wypp@xmu.edu.cn [Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, and The Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen (China)

2015-10-30

Graphical abstract: - Highlights: • Surface complexation and surface precipitation of As on ferrihydrite happen at pH 3–6. • The formation of surface precipitation enhanced As(V) adsorption. • The dissolved Fe{sup 3+} had a good linear relationship with the amount of arsenate re-adsorption. - Abstract: In this study, macroscopic and spectroscopic experimental methods accurately modeled the sorption process of arsenate on ferrihydrite. EXAFS, X-ray diffraction and infrared (IR) spectroscopy indicated that the behavior of As(V) adsorption onto ferrihydrite took place mainly via surface complexation and surface precipitation at acidic pH (3.0–6.0), while the surface precipitation was dominated at longer time intervals and higher Fe{sup 3+} concentration. The macroscopic competitive adsorption experiment between arsenate with phosphate indicated two types of adsorption sites existing on the surface of ferrihydrite, i.e., non-exchangeable sites, which are responsible for a rapid surface complex formation; and exchangeable sites for a slow build-up of surface precipitates. In the slow build-up precipitates, the As(V) surface coverage (mmol/g) exhibited a good linear relationship (R{sup 2} = 0.952) with the amount of dissolved Fe{sup 3+}. Three steps are involved during the process of surface precipitation, i.e., (1) an initial uptake of As(V) via surface complexation; (2) re-adsorption of Fe{sup 3+} leaching from ferrihydrite on the surface complex; and (3) As(V) adsorption via surface complexation again and finally forming the surface precipitate.

Kinetics and thermodynamic for sorption of arsenate by Lanthanum-exchanged zeolite

International Nuclear Information System (INIS)

Mohd Jelas Haron; Saiful Adli Masdan; Mohd Zobir Hussein; Zulkarnain Zainal; Anuar Kassim

2007-01-01

Zeolites are crystalline, hydrated aluminosilicate containing exchangeable alkaline and alkaline earth cations in their structural frameworks. Since zeolites have permanent negative charges on their surfaces, they have no affinity for anions. However recent studies have shown that modification of zeolites with certain surfactants or metal cations yield sorbents with a strong affinity for many anions. In this paper, modification of zeolites (zeolite A, X and ZSM5) were performed by exchange of naturally occurring cations with lanthanum ion that forms low solubility arsenate salt. The exchanged zeolites were used to sorb arsenate from aqueous solution. Among parameters investigated were effect of pH, arsenate initial concentrations, contact time and temperature. The maximum exchanged capacity of La (III) ion was obtained when using solution with initial pH of 4. Zeolite X gives the highest La (III) exchanged capacity compared to other zeolites. The results showed that As (V) sorption by La-zeolites occurred at about pH 6.5 and increased as pH increased and reaching maximum at equilibrium pH about 7.8. On the other hand, almost no arsenate sorption occurred on un exchanged zeolites. This indicates that La (III) ion on the exchanged zeolites is taking part on the As(V) sorption via surface precipitation. The results also showed that the sorption capacities increased with increasing initial As (V) concentrations. The sorption followed Langmuir model with maximum sorption capacities of 0.41, 0.21 and 0.19 mmol/g at 25 degree Celsius for La exchanged zeolite X (La-ZX), La exchanged zeolite ZSM5 (La-ZSM) and La exchanged zeolite A (La-ZA), respectively. The amounts of sorption of As (V) by La exchanged zeolite increased as temperature increased from 25 to 70 degree Celsius indicating that the process is endothermic. The free energy changes ( ΔG degree) for the sorption at 25 degree Celsius were -10.25, -9.65 and -8.49 kJ/ mol for La-ZX, La-ZSM and La-ZA, respectively. The

Effectiveness of Iron Filings in Arsenate and Arsenite Removal from Drinking Water

Directory of Open Access Journals (Sweden)

AliReza Asgari

2009-09-01

Full Text Available Groundwater contamination with arsenic (As has been recognized as a serious problem and there are various reports from different regions, especially from Kurdistan Providence, indicating the presence of As in the from of arsenate and arsenite in water recourses. Removal of these compounds can be accomplished by various methods but they are all expensive. In this study, three concentrations (0.5, 1, and 1 mg/L of iron filings (0.25, 0.5, 1 and 1.5 grams were used as a cheap and available material for adsorption of As and the effects of contact time and pH as well as chloride and sulfate ion concentrations on removal efficiency were determined. Description of adsorption isotherms (Ferundlich and Langmuir was accomplished. Finally, the data obtained were analyzed using the Excel softwere. The results indicate that iron filings show a high capability in adsorbing both arsenate and arsenic compounds from polluted water samples at pH 7 over a short contact time of 30 minutes. In fact, this cheap adsorbent shows good treatment when used at doses as low as 1g/L with no considerable interference by interfering anions (SO42- and Cl-. It appears that the absorbability of both arsenate and arsenite by iron filings can be expressed by Ferundlich isotherm with R2>0.96, whereas arsenate adsorption (with a R2 value of more than 0.96 can be better described by Langmuir isotherm than arsenite (with R2 value of more than 0.91. Results also indicate that the amount of iron added to water is much more than the standard value of 0.3mg/L set for dinking water. Nevertheless, this method has far greater advantages in terms of costs and availability than similar methods. Besides, as removal by this method is efficient without pH modification, iron filing treatment of drinking water may, therefore, be recomnended as a convenient solution to the problem of water resources polluted with As in Iran.

Soil organic matter reduces the sorption of arsenate and phosphate

NARCIS (Netherlands)

Verbeeck, M.; Hiemstra, T.; Thiry, Y.; Smolders, E.

2017-01-01

The arsenate (AsO₄) and phosphate (PO₄) mobility in aerobic soil is affected by soil organic matter (OM). This study was set up to quantify the interaction between OM and AsO₄ with an observational, experimental and computational approach. The adsorption of

Immunocytochemical localization of APS reductase and bisulfite reductase in three Desulfovibrio species

NARCIS (Netherlands)

Kremer, D.R.; Veenhuis, M.; Fauque, G.; Peck Jr., H.D.; LeGall, J.; Lampreia, J.; Moura, J.J.G.; Hansen, T.A.

1988-01-01

The localization of APS reductase and bisulfite reductase in Desulfovibrio gigas, D. vulgaris Hildenborough and D. thermophilus was studied by immunoelectron microscopy. Polyclonal antibodies were raised against the purified enzymes from each strain. Cells fixed with formaldehyde/glutaraldehyde were

Goethite surface reactivity: III. Unifying arsenate adsorption behavior through a variable crystal face - Site density model

Science.gov (United States)

Salazar-Camacho, Carlos; Villalobos, Mario

2010-04-01

We developed a model that describes quantitatively the arsenate adsorption behavior for any goethite preparation as a function of pH and ionic strength, by using one basic surface arsenate stoichiometry, with two affinity constants. The model combines a face distribution-crystallographic site density model for goethite with tenets of the Triple Layer and CD-MUSIC surface complexation models, and is self-consistent with its adsorption behavior towards protons, electrolytes, and other ions investigated previously. Five different systems of published arsenate adsorption data were used to calibrate the model spanning a wide range of chemical conditions, which included adsorption isotherms at different pH values, and adsorption pH-edges at different As(V) loadings, both at different ionic strengths and background electrolytes. Four additional goethite-arsenate systems reported with limited characterization and adsorption data were accurately described by the model developed. The adsorption reaction proposed is: lbond2 FeOH +lbond2 SOH +AsO43-+H→lbond2 FeOAsO3[2-]…SOH+HO where lbond2 SOH is an adjacent surface site to lbond2 FeOH; with log K = 21.6 ± 0.7 when lbond2 SOH is another lbond2 FeOH, and log K = 18.75 ± 0.9, when lbond2 SOH is lbond2 Fe 2OH. An additional small contribution of a protonated complex was required to describe data at low pH and very high arsenate loadings. The model considered goethites above 80 m 2/g as ideally composed of 70% face (1 0 1) and 30% face (0 0 1), resulting in a site density for lbond2 FeOH and for lbond2 Fe 3OH of 3.125/nm 2 each. Below 80 m 2/g surface capacity increases progressively with decreasing area, which was modeled by considering a progressively increasing proportion of faces (0 1 0)/(1 0 1), because face (0 1 0) shows a much higher site density of lbond2 FeOH groups. Computation of the specific proportion of faces, and thus of the site densities for the three types of crystallographic surface groups present in

Neutralization of arsenic pollutants, contained in natural waters: The theoretical analysis of solubility of some arsenates and optimization of the processes

Directory of Open Access Journals (Sweden)

Marta Litynska

2017-01-01

Full Text Available Arsenic belongs to chemical elements, which are often found in natural waters and make it unsuitable for consumption without special treatment. Neutralization of arsenic pollutants of natural waters by converting them into insoluble form is one of the perspective methods of dearsenication. Precipitation (by iron or aluminium coagulants, lime and adsorption (by oxides and hydroxides of iron, aluminium or manganese are among the most popular dearsenication methods. The use of these chemicals entails the formation of poorly soluble arsenates. Since the possibility of the release of arsenic compounds into the water due to the dissolution of formed arsenates depends on its solubility under appropriate conditions, it is necessary to have information about the dependence of arsenates solubility on pH. According to the calculations the solubilities of arsenates of iron(III, aluminium, manganese(II and calcium are highly dependent on pH. At pH

Arsenic accumulation by the aquatic fern Azolla: Comparison of arsenate uptake, speciation and efflux by A. caroliniana and A. filiculoides

Energy Technology Data Exchange (ETDEWEB)

Zhang Xin [State Key Lab of Urban and ONAL Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Lin Aijun [Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zhao Fangjie [Soil Science Department, Rothamsted Research, Hertfordshire AL5 2JQ (United Kingdom); Xu Guozhong [Agricultural Ecology Institute, Fujian Academy of Agricultural Sciences, Fuzhou 350013 (China); Duan Guilan [State Key Lab of Urban and ONAL Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Zhu Yongguan [State Key Lab of Urban and ONAL Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085 (China); Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361003 (China)], E-mail: ygzhu@rcees.ac.cn

2008-12-15

This study investigates As accumulation and tolerance of the aquatic fern Azolla. Fifty strains of Azolla showed a large variation in As accumulation. The highest- and lowest-accumulating ferns among the 50 strains were chosen for further investigations. Azolla caroliniana accumulated two times more As than Azolla filiculoides owing to a higher influx velocity for arsenate. A. filiculoides was more resistant to external arsenate due to a lower uptake. Both strains showed a similar degree of tolerance to internal As. Arsenate and arsenite were the dominant As species in both Azolla strains, with methlyated As species accounting for <5% of the total As. A. filiculoides had a higher proportion of arsenite than A. caroliniana. Both strains effluxed more arsenate than arsenite, and the amount of As efflux was proportional to the amount of As accumulation. The potential of growing Azolla in paddy fields to reduce As transfer from soil and water to rice should be further evaluated. - Arsenic accumulation and efflux differ between strains of the aquatic fern Azolla.

Arsenic accumulation by the aquatic fern Azolla: Comparison of arsenate uptake, speciation and efflux by A. caroliniana and A. filiculoides

International Nuclear Information System (INIS)

Zhang Xin; Lin Aijun; Zhao Fangjie; Xu Guozhong; Duan Guilan; Zhu Yongguan

2008-01-01

This study investigates As accumulation and tolerance of the aquatic fern Azolla. Fifty strains of Azolla showed a large variation in As accumulation. The highest- and lowest-accumulating ferns among the 50 strains were chosen for further investigations. Azolla caroliniana accumulated two times more As than Azolla filiculoides owing to a higher influx velocity for arsenate. A. filiculoides was more resistant to external arsenate due to a lower uptake. Both strains showed a similar degree of tolerance to internal As. Arsenate and arsenite were the dominant As species in both Azolla strains, with methlyated As species accounting for <5% of the total As. A. filiculoides had a higher proportion of arsenite than A. caroliniana. Both strains effluxed more arsenate than arsenite, and the amount of As efflux was proportional to the amount of As accumulation. The potential of growing Azolla in paddy fields to reduce As transfer from soil and water to rice should be further evaluated. - Arsenic accumulation and efflux differ between strains of the aquatic fern Azolla

Oxalic acid as an assisting agent for the electrodialytic remediation of chromated copper arsenate treated timber waste

DEFF Research Database (Denmark)

Ribeiro, Alexandra B.; Mateus, Eduardo P.; Ottosen, Lisbeth M.

1999-01-01

The electrodialytic process is proposed as a technique for the remediation of chromated copper arsenate treated timber waste, using oxalic acid as assisting agent. The method prowed succesfull 93% Cu, 95% Cr and 99% As was removed from the timber.......The electrodialytic process is proposed as a technique for the remediation of chromated copper arsenate treated timber waste, using oxalic acid as assisting agent. The method prowed succesfull 93% Cu, 95% Cr and 99% As was removed from the timber....

Arsenic accumulation by the aquatic fern Azolla: comparison of arsenate uptake, speciation and efflux by A. caroliniana and A. filiculoides.

Science.gov (United States)

Zhang, Xin; Lin, Ai-Jun; Zhao, Fang-Jie; Xu, Guo-Zhong; Duan, Gui-Lan; Zhu, Yong-Guan

2008-12-01

This study investigates As accumulation and tolerance of the aquatic fern Azolla. Fifty strains of Azolla showed a large variation in As accumulation. The highest- and lowest-accumulating ferns among the 50 strains were chosen for further investigations. Azolla caroliniana accumulated two times more As than Azolla filiculoides owing to a higher influx velocity for arsenate. A. filiculoides was more resistant to external arsenate due to a lower uptake. Both strains showed a similar degree of tolerance to internal As. Arsenate and arsenite were the dominant As species in both Azolla strains, with methylated As species accounting for Azolla in paddy fields to reduce As transfer from soil and water to rice should be further evaluated.

Determination of arsenate and organic arsenic via potentiometric titration of its heteropoly anions.

Science.gov (United States)

Metelka, R; Slavíková, S; Vytras, K

2002-08-16

Determination of arsenate based on its conversion to molybdoarsenate heteropoly anions followed by potentiometric titration is described. The titration is realized on the ion-pairing principle using cetylpyridinium chloride (or an analogous titrant containing a lipophilic cation), and is monitored by a carbon paste electrode, although other liquid-polymeric membrane-based electrodes can also be used. Calibration plots of the titrant end-point consumption versus concentration of arsenic were constructed and used to evaluate the content of arsenic in aqueous samples. The method could be applied in the analyses of samples with quite low arsenic content (amounts approximately 10 mug As in 50 cm(3) could be titrated). Organic arsenic was determined analogously after the Schöniger combustion of the sample and conversion of its arsenic to arsenate.

The removal of sulphate from mine water by precipitation as ettringite and the utilisation of the precipitate as a sorbent for arsenate removal.

Science.gov (United States)

Tolonen, Emma-Tuulia; Hu, Tao; Rämö, Jaakko; Lassi, Ulla

2016-10-01

The aim of this research was to investigate sulphate removal from mine water by precipitation as ettringite (Ca6Al2(SO4)3(OH)12·26H2O) and the utilisation of the precipitate as a sorbent for arsenate removal. The mine water sulphate concentration was reduced by 85-90% from the initial 1400 mg/L during ettringite precipitation depending on the treatment method. The precipitation conditions were also simulated with MINEQL + software, and the computational results were compared with the experimental results. The precipitated solids were characterised with X-ray diffraction and a scanning electron microscope. The precipitated solids were tested as sorbents for arsenate removal from the model solution. The arsenic(V) model solution concentration reduced 86-96% from the initial 1.5 mg/L with a 1 g/L sorbent dosage. The effect of initial arsenate concentration on the sorption of arsenate on the precipitate was studied and Langmuir, Freundlich, and Langmuir-Freundlich sorption isotherm models were fitted to the experimental data. The maximum arsenate sorption capacity (qm = 11.2 ± 4.7 mg/g) of the precipitate was obtained from the Langmuir-Freundlich isotherm. The results indicate that the precipitate produced during sulphate removal from mine water by precipitation as ettringite could be further used as a sorbent for arsenate removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

ACCUMULATION AND METABOLISM OF ARSENIC IN MICE AFTER REPEATED ADMINISTRATION OF ARSENATE

Science.gov (United States)

Accumulation and metabolism of arsenic in mice after repeated oral administration of arsenate, Hughes, M. F., Kenyon, E. M., Edwards, B. C., Mitchell, C. T., Del Razo, L. M., and Thomas, D. J. The human carcinogen inorganic arsenic (iAs) is a pervasive environmental ...

Embryotoxicity of arsenite and arsenate. Distribution in pregnant mice and monkeys and effects on embryonic cells in vitro

Energy Technology Data Exchange (ETDEWEB)

Lindgren, A; Danielsson, R G; Dencker, L [Department of Toxicology, Biomedical Center, Uppsala University, Sweden; Vahter, M [National Institute of Environmental Medicine, Stockholm, Sweden

1984-01-01

The distribution of /sup 74/As-labelled arsenate and arsenite in pregnant mice and a monkey has been studied by autoradiography and gamma counting of isolated tissues, and their in vitro toxicity to a chondrogenic system has been investigated. With both arsenic forms, given as single intravenous injections to the mother, the /sup 74/As-arsenic appeared to pass the mouse placenta relatively freely and approximately to the same extent. The retention time in material tissues including the placenta was, however, around three times longer with arsenite than with arsenate. In early gestation, high activity was registered in the embryonic neuroepithelium, which correlates well with reported CNS malformations in rodents. In late gestation, the distribution pattern was more like that in the adults. Accumulation in skin and squamous epithelia of the upper gastrointestinal tract (oral cavity, oesophagus and oesophageal region of stomach) dominated the distribution pucture, especially at a long survival interval. Arsenate, but not arsenite, showed affinity for the calcified areas of the skeleton. A marmoset monkey in late gestation receiving arsenite showed a somewhat lower rate of placental transfer than the mice. Skin and liver had the highest concentrations (at 8 hrs), both in mother and foetuses. This species is known not to methylate arsenic, resulting in stronger binding and longer retention times of arsenic as compared with other species. The stronger binding in maternal tissues may possibly explain the lower rate of placental transfer. Arsenite was shown to inhibit cartilage formation in a chick limb bud mesenchymal spot culture system (ED50 approximately 5-10..mu..M) while arsenate seemed to be without effect at concentrations up to 200 ..mu..M (highest tested). Arsenate, however, showed a potential of the arsenite toxicity.

Na₃Co₂(AsO₄)(As₂O₇): a new sodium cobalt arsenate.

Science.gov (United States)

Guesmi, Abderrahmen; Driss, Ahmed

2012-07-01

In the title compound, tris-odium dicobalt arsenate diarsenate, Na₃Co₂AsO₄As₂O₇, the two Co atoms, one of the two As and three of the seven O atoms lie on special positions, with site symmetries 2 and m for the Co, m for the As, and 2 and twice m for the O atoms. The two Na atoms are disordered over two general and special positions [occupancies 0.72 (3):0.28 (3) and 0.940 (6):0.060 (6), respectively]. The main structural feature is the association of the CoO₆ octa-hedra in the ab plane, forming Co₄O₂₀ units, which are corner- and edge-connected via AsO₄ and As₂O₇ arsenate groups, giving rise to a complex polyhedral connectivity with small tunnels, such as those running along the b- and c-axis directions, in which the Na⁺ ions reside. The structural model is validated by both bond-valence-sum and charge-distribution methods, and the distortion of the coordination polyhedra is analyzed by means of the effective coordination number.

Mode of action of sodium arsenate on laboratory colonies of the pharaoh's ant Monomorium pharaonis L

Energy Technology Data Exchange (ETDEWEB)

Berndt, K P

1974-01-01

Arsenate compounds for pest control have been displayed on large scale by modern insecticides. In the control of the pharaoh's ant the arsenates however still remain an important means for eradication. The present study points out, that the mortality of workers and queens, respectively, are not the decisive factors of action as assumed until now. The causes for the extinction of the ant colonies after application of sodium arsenate are based on a combination of larval mortality and the induction of sterility in the queens, the sterility being the most important factor. A number of other factors moreover are working advantageously. First, the poison bait is not repellent and is well accepted by the workers, and is either stored in the nest or distributed trophalactically. Whereas with the workers there occurs a strongly delayed mortality, the larvae are being inhibited in their development after a few hours, shortly before pupation, or they are being paralyzed, whereby the further pupation would by cut off. The younger larvae normally do not come to pupation, but are being stunted and would be eliminated from the nest. The reproducing females, being the last members in the social chain, are protected in the polygynous society from the lethal action of the poison, although otherwise susceptible in the same way as workers. After a certain time sub-lethal doses of sodium arsenate lead to a decrease in fecundity. Egg production is suppressed dependent on the duration of the poison application up to permanent sterility. On the basis of these investigations some suggestions for practical control of the pharaoh's ant have been derived.

Ketopantoyl-lactone reductase from Candida parapsilosis: purification and characterization as a conjugated polyketone reductase.

Science.gov (United States)

Hata, H; Shimizu, S; Hattori, S; Yamada, H

1989-02-24

Ketopantoyl-lactone reductase (2-dehydropantoyl-lactone reductase, EC 1.1.1.168) was purified and crystallized from cells of Candida parapsilosis IFO 0708. The enzyme was found to be homogeneous on ultracentrifugation, high-performance gel-permeation liquid chromatography and SDS-polyacrylamide gel electrophoresis. The relative molecular mass of the native and SDS-treated enzyme is approximately 40,000. The isoelectric point of the enzyme is 6.3. The enzyme was found to catalyze specifically the reduction of a variety of natural and unnatural polyketones and quinones other than ketopantoyl lactone in the presence of NADPH. Isatin and 5-methylisatin are rapidly reduced by the enzyme, the Km and Vmax values for isatin being 14 microM and 306 mumol/min per mg protein, respectively. Ketopantoyl lactone is also a good substrate (Km = 333 microM and Vmax = 481 mumol/min per mg protein). Reverse reaction was not detected with pantoyl lactone and NADP+. The enzyme is inhibited by quercetin, several polyketones and SH-reagents. 3,4-Dihydroxy-3-cyclobutene-1,2-dione, cyclohexenediol-1,2,3,4-tetraone and parabanic acid are uncompetitive inhibitors for the enzyme, the Ki values being 1.4, 0.2 and 3140 microM, respectively, with isatin as substrate. Comparison of the enzyme with the conjugated polyketone reductase of Mucor ambiguus (S. Shimizu, H. Hattori, H. Hata and H. Yamada (1988) Eur. J. Biochem. 174, 37-44) and ketopantoyl-lactone reductase of Saccharomyces cerevisiae suggested that ketopantoyl-lactone reductase is a kind of conjugated polyketone reductase.

Desulfohalophilus alkaliarsenatis gen. nov., sp. nov., an extremely halophilic sulfate- and arsenate-respiring bacterium from Searles Lake, California

Science.gov (United States)

Blum, Jodi Switzer; Kulp, Thomas R.; Han, Sukkyun; Lanoil, Brian; Saltikov, Chad W.; Stolz, John F.; Miller, Laurence G.; Oremland, Ronald S.

2012-01-01

A haloalkaliphilic sulfate-respiring bacterium, strain SLSR-1, was isolated from a lactate-fed stable enrichment culture originally obtained from the extreme environment of Searles Lake, California. The isolate proved capable of growth via sulfate-reduction over a broad range of salinities (125–330 g/L), although growth was slowest at salt-saturation. Strain SLSR-1 was also capable of growth via dissimilatory arsenate-reduction and displayed an even broader range of salinity tolerance (50–330 g/L) when grown under these conditions. Strain SLSR-1 could also grow via dissimilatory nitrate reduction to ammonia. Growth experiments in the presence of high borate concentrations indicated a greater sensitivity of sulfate-reduction than arsenate-respiration to this naturally abundant anion in Searles Lake. Strain SLSR-1 contained genes involved in both sulfate-reduction (dsrAB) and arsenate respiration (arrA). Amplicons of 16S rRNA gene sequences obtained from DNA extracted from Searles Lake sediment revealed the presence of close relatives of strain SLSR-1 as part of the flora of this ecosystem despite the fact that sulfate-reduction activity could not be detected in situ. We conclude that strain SLSR-1 can only achieve growth via arsenate-reduction under the current chemical conditions prevalent at Searles Lake. Strain SLSR-1 is a deltaproteobacterium in the family Desulfohalobiacea of anaerobic, haloalkaliphilic bacteria, for which we propose the name Desulfohalophilus alkaliarsenatis gen. nov., sp. nov.

Different arsenate and phosphate incorporation effects on the nucleation and growth of iron(III) (Hydr)oxides on quartz.

Science.gov (United States)

Neil, Chelsea W; Lee, Byeongdu; Jun, Young-Shin

2014-10-21

Iron(III) (hydr)oxides play an important role in the geochemical cycling of contaminants in natural and engineered aquatic systems. The ability of iron(III) (hydr)oxides to immobilize contaminants can be related to whether the precipitates form heterogeneously (e.g., at mineral surfaces) or homogeneously in solution. Utilizing grazing incidence small-angle X-ray scattering (GISAXS), we studied heterogeneous iron(III) (hydr)oxide nucleation and growth on quartz substrates for systems containing arsenate and phosphate anions. For the iron(III) only system, the radius of gyration (Rg) of heterogeneously formed precipitates grew from 1.5 to 2.5 (± 1.0) nm within 1 h. For the system containing 10(-5) M arsenate, Rg grew from 3.6 to 6.1 (± 0.5) nm, and for the system containing 10(-5) M phosphate, Rg grew from 2.0 to 4.0 (± 0.2) nm. While the systems containing these oxyanions had more growth, the system containing only iron(III) had the most nucleation events on substrates. Ex situ analyses of homogeneously and heterogeneously formed precipitates indicated that precipitates in the arsenate system had the highest water content and that oxyanions may bridge iron(III) hydroxide polymeric embryos to form a structure similar to ferric arsenate or ferric phosphate. These new findings are important because differences in nucleation and growth rates and particle sizes will impact the number of available reactive sites and the reactivity of newly formed particles toward aqueous contaminants.

Mediator, SWI/SNF and SAGA complexes regulate Yap8-dependent transcriptional activation of ACR2 in response to arsenate.

Science.gov (United States)

Menezes, Regina Andrade; Pimentel, Catarina; Silva, Ana Rita Courelas; Amaral, Catarina; Merhej, Jawad; Devaux, Frédéric; Rodrigues-Pousada, Claudina

2017-04-01

Response to arsenic stress in Saccharomyces cerevisiae is orchestrated by the regulatory protein Yap8, which mediates transcriptional activation of ACR2 and ACR3. This study contributes to the state of art knowledge of the molecular mechanisms underlying yeast stress response to arsenate as it provides the genetic and biochemical evidences that Yap8, through cysteine residues 132, 137, and 274, is the sensor of presence of arsenate in the cytosol. Moreover, it is here reported for the first time the essential role of the Mediator complex in the transcriptional activation of ACR2 by Yap8. Based on our data, we propose an order-of-function map to recapitulate the sequence of events taking place in cells injured with arsenate. Modification of the sulfhydryl state of these cysteines converts Yap8 in its activated form, triggering the recruitment of the Mediator complex to the ACR2/ACR3 promoter, through the interaction with the tail subunit Med2. The Mediator complex then transfers the regulatory signals conveyed by Yap8 to the core transcriptional machinery, which culminates with TBP occupancy, ACR2 upregulation and cell adaptation to arsenate stress. Additional co-factors are required for the transcriptional activation of ACR2 by Yap8, particularly the nucleosome remodeling activity of SWI/SNF and SAGA complexes. Copyright © 2017. Published by Elsevier B.V.

The structure of apo and holo forms of xylose reductase, a dimeric aldo-keto reductase from Candida tenuis.

Science.gov (United States)

Kavanagh, Kathryn L; Klimacek, Mario; Nidetzky, Bernd; Wilson, David K

2002-07-16

Xylose reductase is a homodimeric oxidoreductase dependent on NADPH or NADH and belongs to the largely monomeric aldo-keto reductase superfamily of proteins. It catalyzes the first step in the assimilation of xylose, an aldose found to be a major constituent monosaccharide of renewable plant hemicellulosic material, into yeast metabolic pathways. It does this by reducing open chain xylose to xylitol, which is reoxidized to xylulose by xylitol dehydrogenase and metabolically integrated via the pentose phosphate pathway. No structure has yet been determined for a xylose reductase, a dimeric aldo-keto reductase or a family 2 aldo-keto reductase. The structures of the Candida tenuis xylose reductase apo- and holoenzyme, which crystallize in spacegroup C2 with different unit cells, have been determined to 2.2 A resolution and an R-factor of 17.9 and 20.8%, respectively. Residues responsible for mediating the novel dimeric interface include Asp-178, Arg-181, Lys-202, Phe-206, Trp-313, and Pro-319. Alignments with other superfamily members indicate that these interactions are conserved in other dimeric xylose reductases but not throughout the remainder of the oligomeric aldo-keto reductases, predicting alternate modes of oligomerization for other families. An arrangement of side chains in a catalytic triad shows that Tyr-52 has a conserved function as a general acid. The loop that folds over the NAD(P)H cosubstrate is disordered in the apo form but becomes ordered upon cosubstrate binding. A slow conformational isomerization of this loop probably accounts for the observed rate-limiting step involving release of cosubstrate. Xylose binding (K(m) = 87 mM) is mediated by interactions with a binding pocket that is more polar than a typical aldo-keto reductase. Modeling of xylose into the active site of the holoenzyme using ordered waters as a guide for sugar hydroxyls suggests a convincing mode of substrate binding.

Conversion of agricultural residues into activated carbons for water purification: Application to arsenate removal.

Science.gov (United States)

Torres-Perez, Jonatan; Gerente, Claire; Andres, Yves

2012-01-01

The conversion of two agricultural wastes, sugar beet pulp and peanut hulls, into sustainable activated carbons is presented and their potential application for the treatment of arsenate solution is investigated. A direct and physical activation is selected as well as a simple chemical treatment of the adsorbents. The material properties, such as BET surface areas, porous volumes, elemental analysis, ash contents and pH(PZC), of these alternative carbonaceous porous materials are determined and compared with a commercial granular activated carbon. An adsorption study based on experimental kinetic and equilibrium data is conducted in a batch reactor and completed by the use of different models (intraparticle diffusion, pseudo-second-order, Langmuir and Freundlich) and by isotherms carried out in natural waters. It is thus demonstrated that sugar beet pulp and peanut hulls are good precursors to obtain activated carbons for arsenate removal.

New Approach to Remove Metals from Chromated Copper Arsenate (CCA)-Treated Wood

Science.gov (United States)

Todd F. Shupe; Chung Y. Hse; Hui Pan

2012-01-01

Recovery of metals from chromated copper arsenate (CCA)-treated southern pine wood particles was investigated using binary acid solutions consisting of acetic, oxalic, and phosphoric acids in a microwave reactor. Formation of an insoluble copper oxalate complex in the binary solution containing oxalic acid was the major factor for low copper removal. Furthermore, the...

Hepatoprotective effects of hexane root extract of Alchornea laxiflora in sodium arsenate toxicity in wistar albino rats

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Esosa Samuel Uhunmwangho

2018-01-01

Full Text Available Background: Medicinal plants are have been used in the treatment of myriad disease conditions, Alchornea laxiflora is one of such medicinal plant. Aim: To investigate the hepatoprotective effect of hexane root extract of Alchornea laxiflora against sodium arsenate induced liver damage in wistar male rats. Setting and Design: Extraction and administration of bioactive extract. Materials and Methods: Extraction of air-dried ground root of Alchornea laxiflora was done by extracting 500 g with 500 cm of 95% hexane for 72 hrs.The animals (120-150 g were pre-treated with the extract at varying doses (0.1, 0.5, 1.0, 10, 50 and 100 mg/kg body weight for seven days orally prior to the intra-peritoneal administration of the toxicant (sodium arsenate at a dose of 2 mg/kg body weight at the eight day. Hepatoprotective activity of the extracts was evaluated by studying the Cytochrome b5content, Glutathione-S-transferase and 4- Nitroanisole-o-demethylase activities in the liver, Plasma levels of Alanine aminotransferase (AST, Alanine aminotransferase (ALT, Alkaline phosphatase (ALP and the levels of Total protein, Albumin, Globulin and Glutathione of the various groups. Statistical Analysis: The data were analysed with Microsoft excels (for windows 2007 and Student t-test and ANOVA. Result and Conclusion: The results suggest that pre-treatment of rats with hexane root extract of Alchornea laxiflora for seven days reduced the elevated levels of liver enzymes, reduced the levels of induced liver metabolizing enzymes and the levels of Total protein, Albumin, Globulin and Glutathione that was increased by the toxicity of sodium arsenate in rats and as such possess hepatoprotective effect against sodium arsenate.

The removal of arsenate from water using iron-modified diatomite (D-Fe): isotherm and column experiments.

Science.gov (United States)

Pantoja, M L; Jones, H; Garelick, H; Mohamedbakr, H G; Burkitbayev, M

2014-01-01

Iron hydroxide supported onto porous diatomite (D-Fe) is a low-cost material with potential to remove arsenic from contaminated water due to its affinity for the arsenate ion. This affinity was tested under varying conditions of pH, contact time, iron content in D-Fe and the presence of competitive ions, silicate and phosphate. Batch and column experiments were conducted to derive adsorption isotherms and breakthrough behaviours (50 μg L(-1)) for an initial concentration of 1,000 μg L(-1). Maximum capacity at pH 4 and 17% iron was 18.12-40.82 mg of arsenic/g of D-Fe and at pH 4 and 10% iron was 18.48-29.07 mg of arsenic/g of D-Fe. Adsorption decreased in the presence of phosphate and silicate ions. The difference in column adsorption behaviour between 10% and 17% iron was very pronounced, outweighing the impact of all other measured parameters. There was insufficient evidence of a correlation between iron content and arsenic content in isotherm experiments, suggesting that ion exchange is a negligible process occurring in arsenate adsorption using D-Fe nor is there co-precipitation of arsenate by rising iron content of the solute above saturation.

Optimization of arsenic removal water treatment system through characterization of terminal electron accepting processes.

Science.gov (United States)

Upadhyaya, Giridhar; Clancy, Tara M; Brown, Jess; Hayes, Kim F; Raskin, Lutgarde

2012-11-06

Terminal electron accepting process (TEAP) zones developed when a simulated groundwater containing dissolved oxygen (DO), nitrate, arsenate, and sulfate was treated in a fixed-bed bioreactor system consisting of two reactors (reactors A and B) in series. When the reactors were operated with an empty bed contact time (EBCT) of 20 min each, DO-, nitrate-, sulfate-, and arsenate-reducing TEAP zones were located within reactor A. As a consequence, sulfate reduction and subsequent arsenic removal through arsenic sulfide precipitation and/or arsenic adsorption on or coprecipitation with iron sulfides occurred in reactor A. This resulted in the removal of arsenic-laden solids during backwashing of reactor A. To minimize this by shifting the sulfate-reducing zone to reactor B, the EBCT of reactor A was sequentially lowered from 20 min to 15, 10, and 7 min. While 50 mg/L (0.81 mM) nitrate was completely removed at all EBCTs, more than 90% of 300 μg/L (4 μM) arsenic was removed with the total EBCT as low as 27 min. Sulfate- and arsenate-reducing bacteria were identified throughout the system through clone libraries and quantitative PCR targeting the 16S rRNA, dissimilatory (bi)sulfite reductase (dsrAB), and dissimilatory arsenate reductase (arrA) genes. Results of reverse transcriptase (RT) qPCR of partial dsrAB (i.e., dsrA) and arrA transcripts corresponded with system performance. The RT qPCR results indicated colocation of sulfate- and arsenate-reducing activities, in the presence of iron(II), suggesting their importance in arsenic removal.

Role of uniform pore structure and high positive charges in the arsenate adsorption performance of Al13-modified montmorillonite

International Nuclear Information System (INIS)

Zhao, Shou; Feng, Chenghong; Huang, Xiangning; Li, Baohua; Niu, Junfeng; Shen, Zhenyao

2012-01-01

Highlights: ► Al 13 modification changes As(V) sorption mechanism of montmorillonites. ► Intercalated ion charges mainly affects As(V) adsorption kinetics. ► Uniform pore structure exhibit more excellent As(V) adsorption performance. - Abstract: Four modified montmorillonite adsorbents with varied Al 13 contents (i.e., Na-Mont, AC-Mont, PAC 20 -Mont, and Al 13 -Mont) were synthesized and characterized by N 2 adsorption/desorption, X-ray diffraction, and Fourier-transform infrared analyses. The arsenate adsorption performance of the four adsorbents were also investigated to determine the role of intercalated Al 13 , especially its high purity, high positive charge (+7), and special Keggin structure. With increased Al 13 content, the physicochemical properties (e.g., surface area, structural uniformity, basal spacing, and pore volume) and adsorption performance of the modified montmorillonites were significantly but disproportionately improved. The adsorption data well fitted the Freundlich and Redlich–Peterson isotherm model, whereas the kinetic data better correlated with the pseudo-second-order kinetic model. The arsenate sorption mechanism of the montmorillonites changed from physical to chemisorption after intercalation with Al 13 . Increasing charges of the intercalated ions enhanced the arsenate adsorption kinetics, but had minimal effect on the structural changes of the montmorillonites. The uniform pore structure formed by intercalation with high-purity Al 13 greatly enhanced the pore diffusion and adsorption rate of arsenate, resulting in the high adsorption performance of Al 13 -Mont.

Characterization of ferric arsenate-sulfate compounds: Implications for arsenic control in refractory gold processing residues

Czech Academy of Sciences Publication Activity Database

Paktunc, D.; Majzlan, J.; Palatinus, Lukáš; Dutrizac, J.; Klementová, Mariana; Poirier, G.

2013-01-01

Roč. 98, č. 4 (2013), s. 554-565 ISSN 0003-004X Institutional support: RVO:68378271 Keywords : arsenic * ferric arsenate sulfate * autoclave residue * hydrometallurgy Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.059, year: 2013

Activity of the Respiratory Chain Enzymes of Blood Leucocytes’ Mitochondria Under the Conditions of Toxic Hepatitis Induced Against the Background Alimentary Deprivation of Protein

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O.N. Voloshchuk

2015-12-01

Full Text Available Full functioning of the leucocytes’ energy supply system is one of the essential factors for the immune surveillance system effective work. The pivotal enzymes of the leucocytes’ energy biotransformation system are NADH-ubiquitin reductase, a marker of the Complex I of respiratory chain activity, and succinate dehydrogenase, key enzyme of the Complex II of respiratory chain. The aim of research – to study the NADH-ubiquitin reductase and succinate dehydrogenase activity of the blood leucocytes’ mitochondria under the conditions of toxic hepatitis induced against the background alimentary deprivation of protein. It is shown, that under the conditions of acetaminophen-induced hepatitis a reduction of the NADH-ubiquitin reductase enzymatic activity is observed on the background activation of the succinate-dependent way of the mitochondrial oxidation. Conclusion was made that alimentary deprivation or protein is a factor, aggravating the misbalance of the energy biotransformation system in the leucocytes of rats with toxic hepatitis. Established activity changes of the leucocytes’ mitochondria respiratory chain key enzymes may be considered as one of the mechanisms, directed on the maintenance of leucocytes energy supply on a level, sufficient for their functioning. Research results may be used for the biochemical rationale of the therapeutic approaches to the elimination and correction of the leucocytes’ energy metabolism disturbances consequences under the conditions of acetaminophen-induced hepatitis, aggravated by the alimentary protein deprivation.

The aldo-keto reductase superfamily homepage.

Science.gov (United States)

Hyndman, David; Bauman, David R; Heredia, Vladi V; Penning, Trevor M

2003-02-01

The aldo-keto reductases (AKRs) are one of the three enzyme superfamilies that perform oxidoreduction on a wide variety of natural and foreign substrates. A systematic nomenclature for the AKR superfamily was adopted in 1996 and was updated in September 2000 (visit www.med.upenn.edu/akr). Investigators have been diligent in submitting sequences of functional proteins to the Web site. With the new additions, the superfamily contains 114 proteins expressed in prokaryotes and eukaryotes that are distributed over 14 families (AKR1-AKR14). The AKR1 family contains the aldose reductases, the aldehyde reductases, the hydroxysteroid dehydrogenases and steroid 5beta-reductases, and is the largest. Other families of interest include AKR6, which includes potassium channel beta-subunits, and AKR7 the aflatoxin aldehyde reductases. Two new families include AKR13 (yeast aldose reductase) and AKR14 (Escherichia coli aldehyde reductase). Crystal structures of many AKRs and their complexes with ligands are available in the PDB and accessible through the Web site. Each structure has the characteristic (alpha/beta)(8)-barrel motif of the superfamily, a conserved cofactor binding site and a catalytic tetrad, and variable loop structures that define substrate specificity. Although the majority of AKRs are monomeric proteins of about 320 amino acids in length, the AKR2, AKR6 and AKR7 family may form multimers. To expand the nomenclature to accommodate multimers, we recommend that the composition and stoichiometry be listed. For example, AKR7A1:AKR7A4 (1:3) would designate a tetramer of the composition indicated. The current nomenclature is recognized by the Human Genome Project (HUGO) and the Web site provides a link to genomic information including chromosomal localization, gene boundaries, human ESTs and SNPs and much more.

Tetrathionate reductase of Salmonella thyphimurium: a molybdenum containing enzyme

International Nuclear Information System (INIS)

Hinojosa-Leon, M.; Dubourdieu, M.; Sanchez-Crispin, J.A.; Chippaux, M.

1986-01-01

Use of radioactive molybdenum demonstrates that the tetrathionate reductase of Salmonella typhimurium is a molydenum containing enzyme. It is proposed that this enzyme shares with other molybdo-proteins, such as nitrate reductase, a common molybdenum containing cofactor the defect of which leads to the loss of the tetrathionate reductase and nitrate reductase activities

Two Lactococcus lactis thioredoxin paralogues play different roles in responses to arsenate and oxidative stress

DEFF Research Database (Denmark)

Efler, Petr; Kilstrup, Mogens; Johnsen, Stig

2015-01-01

Thioredoxin (Trx) maintains intracellular thiol groups in a reduced state and is involved in a wide range of cellular processes, including ribonucleotide reduction, sulphur assimilation, oxidative stress responses and arsenate detoxification. The industrially important lactic acid bacterium...... Lactococcus lactis contains two Trxs. TrxA is similar to the well-characterized Trx homologue from Escherichia coli and contains the common WCGPC active site motif, while TrxD is atypical and contains an aspartate residue in the active site (WCGDC). To elucidate the physiological roles of the two Trx...... to the wild-type. The lack of TrxA also appears to impair methionine sulphoxide reduction. Both ΔtrxA and ΔtrxD strains displayed growth inhibition after treatment with sodium arsenate and tellurite as compared with the wild-type, suggesting partially overlapping functions of TrxA and TrxD. Overall...

Oxygen and xenobiotic reductase activities of cytochrome P450.

NARCIS (Netherlands)

Goeptar, A.R.; Scheerens, H.; Vermeulen, N.P.E.

1995-01-01

The oxygen reductase and xenobiotic reductase activities of cytochrome P450 (P450) are reviewed. During the oxygen reductase activity of P450, molecular oxygen is reduced to superoxide anion radicals (O

Structure and mechanism of dimethylsulfoxide reductase, a molybdopterin-containing enzyme of DMSO reductase family

International Nuclear Information System (INIS)

McEwan, A.G.; Ridge, J.P.; McDevitt, C.A.; Hanson, G.R.

2001-01-01

Full text: Apart from nitrogenase, enzymes containing molybdenum are members of a superfamily, the molybdopterin-containing enzymes. Most of these enzymes catalyse an oxygen atom transfer and two electron transfer reaction. During catalysis the Mo at the active site cycles between the Mo(VI) and Mo(IV) states. The DMSO reductase family of molybdopterin-containing enzymes all contain a bis(molybdopterin guanine dinucleotide)Mo cofactor and over thirty examples have now been described. Over the last five years crystal structures of dimethylsulfoxide (DMSO) reductase and four other enzymes of the DMSO reductase family have revealed that enzymes of this family have a similar tertiary structure. The Mo atom at the active site is coordinated by four thiolate ligands provided by the dithiolene side chains of the two MGD molecules of the bis(MGD)Mo cofactor as well as a ligand provided by an amino acid side chain. In addition, an oxygen atom in the form of an oxo, hydroxo or aqua group is also coordinated to the Mo atom. In the case of dimethylsulfoxide reductase X-ray crystallography of the product-reduced species and Raman spectroscopy has demonstrated that the enzyme contains a single exchangeable oxo group that is H-bonded to W116

Embryotoxicity of arsenite and arsenate. Distribution in pregnant mice and monkeys and effects on embryonic cells in vitro

Energy Technology Data Exchange (ETDEWEB)

Lindgren, A; Danielsson, R G; Dencker, L [Department of Toxicology, Biomedical Center, Uppsala University, Sweden; Vahter, M [National Institute of Environmental Medicine, Stockholm, Sweden

1984-01-01

The distribution of /sup 74/As-labelled and arsenite in pregnant mice and a monkey has been studied by autoradiography and gamma counting of isolated tissues, and their in vitro toxicity to a chondrogenic system has been investigated. With both arsenic forms, given as single intravenous injections to the mother, the /sup 74/As-arsenic appeared to pass the mouse placenta relatively freely and approximately to the same extent. The retention time in material tissues including the placenta was, however, around three times longer with arsenite than with arsenate. In early gestation, high activity was registered in the embryonic neuroepithelium, which correlates well with reported CNS malformations in rodents. In late gestation, the distribution pattern was more like that in the adults. Accumulation in skin and squamous epithelia of the upper gastrointestinal tract (oral cavity, oesophagus and oesophageal region of stomach) dominated the distribution picture, especially at a long survival interval. Arsenate, but not arsenite, showed affinity for the calcified areas of the skeleton. A marmoset monkey in late gestation receiving arsenite showed a somewhat lower rate of placental transfer than the mice. Skin and liver had the highest concentrations (at 8 hrs), both in mother and foetuses. This species is known not to methylate arsenic, resulting in stronger binding and longer retention times of arsenic as compared with other species. The stronger binding in maternal tissues may possibly explain the lower rate of placental transfer. Arsenite was shown to inhibit cartilage formation in a chick limb bud mesenchymal spot culture system (ED50 approximately 5-10..mu..M) while arsenate seemed to be without effect at concentrations up to 200 ..mu..M (highest tested). Arsenate, however, showed a potential of the arsenite toxicity.

Genomic responses to arsenic in the cyanobacterium Synechocystis sp. PCC 6803.

Directory of Open Access Journals (Sweden)

Ana María Sánchez-Riego

Full Text Available Arsenic is a ubiquitous contaminant and a toxic metalloid which presents two main redox states in nature: arsenite [As(III] and arsenate [As(V]. Arsenic resistance in Synechocystis sp. strain PCC 6803 is mediated by the arsBHC operon and two additional arsenate reductases encoded by the arsI1 and arsI2 genes. Here we describe the genome-wide responses to the presence of arsenate and arsenite in wild type and mutants in the arsenic resistance system. Both forms of arsenic produced similar responses in the wild type strain, including induction of several stress related genes and repression of energy generation processes. These responses were transient in the wild type strain but maintained in time in an arsB mutant strain, which lacks the arsenite transporter. In contrast, the responses observed in a strain lacking all arsenate reductases were somewhat different and included lower induction of genes involved in metal homeostasis and Fe-S cluster biogenesis, suggesting that these two processes are targeted by arsenite in the wild type strain. Finally, analysis of the arsR mutant strain revealed that ArsR seems to only control 5 genes in the genome. Furthermore, the arsR mutant strain exhibited hypersentivity to nickel, copper and cadmium and this phenotype was suppressed by mutation in arsB but not in arsC gene suggesting that overexpression of arsB is detrimental in the presence of these metals in the media.

Effects of lead arsenate sprays on the fruit growth and sugar and acid contents in Natsudaidai (Citrus natsudaidai Hayata)

Energy Technology Data Exchange (ETDEWEB)

Kadoya, K; Kuraoka, T; Matsumoto, K

1965-01-01

The juice of the fruit of Citrus natsudaidai is characterized by high acidity. The acidity of the juice was most effectively reduced by treatment with lead arsenate spray at an early fruit growth stage when the acids were being most actively formed. The water-soluble organic acid content of leaves was not affected. The sugar content of the juice was increased by the treatment. The activity of phosphoenolpyruvate carboxylase was lowered in the vesicles of fruit sprayed with lead arsenate. It was also much depressed in the extracts from normal fruit when arsenic trioxide was added. Arsenic was detected in the vesicles of treated fruit. 15 references, 9 figures.

ASSESSING CHILDREN'S EXPOSURES TO THE WOOD PRESERVATIVE CCA (CHROMATED COPPER ARSENATE) ON TREATED PLAYSETS AND DECKS

Science.gov (United States)

Concerns have been raised regarding the safety of young children contacting arsenic and chromium residues while playing on and around Chromated Copper Arsenate (CCA) treated wood playground structures and decks. Although CCA registrants voluntarily canceled treated wood for re...

Effect of ionophores on phosphate and arsenate transport in Micrococcus lysodeikticus

Energy Technology Data Exchange (ETDEWEB)

Friedberg, I

1977-09-01

The effects of ionophores on P/sub i/ and arsenate transport, at acid and alkaline environment, were investigated in whole cells of Micrococcus lysodeikticus, a Gram positive obligatory aerobic bacterium. The results suggest that both ..delta.. Psi and ..delta.. pH contribute to the driving force of P/sub i/ transport; ..delta.. Psi seems to be predominant at pH 7.8, whereas at pH 5.5, the transport is primarily driven by ..delta.. pH. 12 references, 1 figure.

The arbuscular mycorrhizal fungus Glomus mosseae can enhance arsenic tolerance in Medicago truncatula by increasing plant phosphorus status and restricting arsenate uptake

International Nuclear Information System (INIS)

Xu Pengliang; Christie, Peter; Liu Yu; Zhang Junling; Li Xiaolin

2008-01-01

A pot experiment examined the biomass and As uptake of Medicago truncatula colonized by the arbuscular mycorrhizal (AM) fungus Glomus mosseae in low-P soil experimentally contaminated with different levels of arsenate. The biomass of G. mosseae external mycelium was unaffected by the highest addition level of As studied (200 mg kg -1 ) but shoot and root biomass declined in both mycorrhizal and non-mycorrhizal plants, indicating that the AM fungus was more tolerant than M. truncatula to arsenate. Mycorrhizal inoculation increased shoot and root dry weights by enhancing host plant P nutrition and lowering shoot and root As concentrations compared with uninoculated plants. The AM fungus may have been highly tolerant to As and conferred enhanced tolerance to arsenate on the host plant by enhancing P nutrition and restricting root As uptake. - G. mosseae was more tolerant than M. truncatula to As and may have conferred enhanced host tolerance by restricting root As uptake and enhancing P nutrition

The arbuscular mycorrhizal fungus Glomus mosseae can enhance arsenic tolerance in Medicago truncatula by increasing plant phosphorus status and restricting arsenate uptake

Energy Technology Data Exchange (ETDEWEB)

Xu Pengliang [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Christie, Peter [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Agricultural and Environmental Science Department, Queen' s University Belfast, Belfast BT9 5PX (United Kingdom); Liu Yu [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Zhang Junling [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China)], E-mail: junlingz@cau.edu.cn; Li Xiaolin [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China)

2008-11-15

A pot experiment examined the biomass and As uptake of Medicago truncatula colonized by the arbuscular mycorrhizal (AM) fungus Glomus mosseae in low-P soil experimentally contaminated with different levels of arsenate. The biomass of G. mosseae external mycelium was unaffected by the highest addition level of As studied (200 mg kg{sup -1}) but shoot and root biomass declined in both mycorrhizal and non-mycorrhizal plants, indicating that the AM fungus was more tolerant than M. truncatula to arsenate. Mycorrhizal inoculation increased shoot and root dry weights by enhancing host plant P nutrition and lowering shoot and root As concentrations compared with uninoculated plants. The AM fungus may have been highly tolerant to As and conferred enhanced tolerance to arsenate on the host plant by enhancing P nutrition and restricting root As uptake. - G. mosseae was more tolerant than M. truncatula to As and may have conferred enhanced host tolerance by restricting root As uptake and enhancing P nutrition.

Concentration and chemical status of arsenic in the blood of pregnant hamsters during critical embryogenesis. 1. Subchronic exposure to arsenate utilizing constant rate administration

Energy Technology Data Exchange (ETDEWEB)

Hanlon, D.P.; Ferm, V.H.

1986-08-01

The concentration, availability, and chemical status of radiolabeled arsenic has been determined in the blood of pregnant hamsters at the beginning (morning of Day 8) and the end (morning of Day 9) of the critical period of embryogenesis. Hamster dams were exposed to teratogenic doses of arsenate by means of osmotic minipumps implanted on the morning of Day 6 of the gestation period. Whole blood arsenic concentrations were the same for 48 and 72 hr postimplant. The arsenic concentration of plasma equaled that of red cells. Plasma arsenic was not bound to macromolecules and had the same chemical status 48 and 72 hr postimplant. Arsenate was the dominant form (67% of the total). However, the presence of dimethylarsinic acid and arsenite indicates that the pentavalent species was metabolized. Red cell arsenic was bound to macromolecules in the cell sap. Seventy percent of red cell sap arsenic was dialyzable 48 hr postimplant, but only 56% 72 hr postimplant. Arsenate was the dominant dialyzable red cell species on Day 8 and arsenite was the major dialyzable form on Day 9. The authors findings demonstrate a relationship between the maternal blood concentration and chemical status of arsenic and the presence of malformations resulting from a constant rate exposure of pregnant hamsters to arsenate via the osmotic minipump.

Concentration and chemical status of arsenic in the blood of pregnant hamsters during critical embryogenesis. 1. Subchronic exposure to arsenate utilizing constant rate administration

International Nuclear Information System (INIS)

Hanlon, D.P.; Ferm, V.H.

1986-01-01

The concentration, availability, and chemical status of radiolabeled arsenic has been determined in the blood of pregnant hamsters at the beginning (morning of Day 8) and the end (morning of Day 9) of the critical period of embryogenesis. Hamster dams were exposed to teratogenic doses of arsenate by means of osmotic minipumps implanted on the morning of Day 6 of the gestation period. Whole blood arsenic concentrations were the same for 48 and 72 hr postimplant. The arsenic concentration of plasma equaled that of red cells. Plasma arsenic was not bound to macromolecules and had the same chemical status 48 and 72 hr postimplant. Arsenate was the dominant form (67% of the total). However, the presence of dimethylarsinic acid and arsenite indicates that the pentavalent species was metabolized. Red cell arsenic was bound to macromolecules in the cell sap. Seventy percent of red cell sap arsenic was dialyzable 48 hr postimplant, but only 56% 72 hr postimplant. Arsenate was the dominant dialyzable red cell species on Day 8 and arsenite was the major dialyzable form on Day 9. The authors findings demonstrate a relationship between the maternal blood concentration and chemical status of arsenic and the presence of malformations resulting from a constant rate exposure of pregnant hamsters to arsenate via the osmotic minipump

Effects of Chronic Exposure to Sodium Arsenate on Kidney of Rats

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Namdar Yousofvand

2015-09-01

Full Text Available Background: In the present study, histopathological effects of chronic exposure to sodium arsenate in drinkable water were studied on a quantity of organs of rat. Methods: Rats were divided into two groups, group I; served as control group, were main-tained on deionized drinkable water for 2 months, and group II; the study group were given 60 g/ml of sodium arsenate in deionized drinkable water for 2 months. Blood and urine samples from two groups of animals were collected under anesthesia and the animals were sacrificed under deep anesthesia (a-chloralose, 100 mg/kg, I.P. Their kidney, liver, aorta, and heart were dissected out and cleaned of surrounding connective tissue. The organs were kept in formaldehyde (10% for histopathologic examination. Serum and urine samples from two groups were collected and analyzed for arsenic level. Total quantity of arsenic in serum and urine of animal was measured through graphic furnace atomic absorption spectrometry (GF-AAS. Results:Examination with light microscopy did not show any visible structural changes in the aorta, myocardium, and liver of chronic arsenic treated animals.However, a significant effect was observed in the kidneys of chronic arsenic treated rats showing distinct changes in proxi-mal tubular cells. There was high concentration of arsenic in serum and urine of arsenic ex-posed animals (group II significantly (P<0.001. Conclusion:Swollen tubular cells in histopathologic study of kidney may suggest toxic effects of arsenic in the body.

Recombinant pinoresinol/lariciresinol reductase, recombinant dirigent protein, and methods of use

Science.gov (United States)

Lewis, Norman G.; Davin, Laurence B.; Dinkova-Kostova, Albena T.; Fujita, Masayuki; Gang, David R.; Sarkanen, Simo; Ford, Joshua D.

2001-04-03

Dirigent proteins and pinoresinol/lariciresinol reductases have been isolated, together with cDNAs encoding dirigent proteins and pinoresinol/lariciresinol reductases. Accordingly, isolated DNA sequences are provided which code for the expression of dirigent proteins and pinoresinol/lariciresinol reductases. In other aspects, replicable recombinant cloning vehicles are provided which code for dirigent proteins or pinoresinol/lariciresinol reductases or for a base sequence sufficiently complementary to at least a portion of dirigent protein or pinoresinol/lariciresinol reductase DNA or RNA to enable hybridization therewith. In yet other aspects, modified host cells are provided that have been transformed, transfected, infected and/or injected with a recombinant cloning vehicle and/or DNA sequence encoding dirigent protein or pinoresinol/lariciresinol reductase. Thus, systems and methods are provided for the recombinant expression of dirigent proteins and/or pinoresinol/lariciresinol reductases.

Protective role of vitamin C and E against sodium arsenate induced changes in developing kidney of albino mice

International Nuclear Information System (INIS)

Qureshi, F.; Tahir, M.; Sami, W.

2009-01-01

Background: Arsenic is a teratogenic agent present in the environment as oxides and arsenate and humans are exposed to it through contaminated drinking water, food, soil and air. This investigation was undertaken to evaluate protective role of Vitamin C and E against teratogenic injury produced by sodium arsenate in developing kidney of the mouse. Methods: Twenty-four pregnant albino mice of BALB/c strain, were randomly divided into 4 groups of 6 each: A1, A2, A3 and A4. Group A1 served as the control and received weight related distilled water by intra-peritoneal (I/P) injection, group A2 was given a single doses of 35 mg/kg on 8 GD whereas groups A3 and A4 were treated with Vitamin C and E by IP injection, 9 mg/kg/day and 15 mg/kg/day respectively, starting from 8 day and continued for the rest of the pregnancy period. The foetal kidneys were weighed and histological studies carried out including micrometry on different components of nephron. Results: Sodium arsenate toxicity manifested as an increase in weight of the kidneys, wider nephrogenic zone and significant reduction in the mean of number of mature renal corpuscles as compared to the control group (p<0.000). There were moderate to severe necrotic and degenerative changes in proximal and distal convoluted tubules; glomeruli were hyper cellular, the Bowman's spaces were obliterated. There was a statistically significant difference in mean diameter of renal corpuscles of group A2 when compared with groups A1, A3 and A4, (p<0.000). Conclusions: The findings implied that groups receiving Vitamin C and E along with sodium arsenate showed an overall improvement in all parameters, indicating the protective role of Vitamin C and E against arsenic induced teratogenicity in developing kidney and are safe to use during pregnancy without deleterious effect on human conspectuses in arsenic exposed areas. (author)

Is the effect of silicon on rice uptake of arsenate (AsV) related to internal silicon concentrations, iron plaque and phosphate nutrition?

International Nuclear Information System (INIS)

Guo, W.; Zhu, Y.-G.; Liu, W.-J.; Liang, Y.-C.; Geng, C.-N.; Wang, S.-G.

2007-01-01

Solution culture experiments were conducted to investigate the effects of silicon (Si) on arsenate (As V ) uptake by rice. The addition of Si to the pretreatment or uptake solution significantly decreased shoot and root As concentrations (P < 0.001 and P < 0.05). The presence of Si in the pretreatment or uptake solution also significantly decreased shoot P concentrations (P < 0.001). The data demonstrated that both internal and external Si inhibited the uptake of As and P. Results of As uptake kinetics showed that the mechanism of the effect of Si on arsenate uptake is not caused by direct competition for active sites of transporters with As. The effect of Si on As uptake was not entirely mediated through the effect of Si on P uptake. Although the addition of Si to pretreatment solutions still significantly decreased shoot and root As concentrations, the extent of reduction became smaller when rice roots were coated with iron plaque. - Arsenate uptake by rice seedlings is affected by both Si (internal and external) and iron plaque on root surface

Bioinformatics approach of three partial polyprenol reductase genes in Kandelia obovata

Science.gov (United States)

Basyuni, M.; Wati, R.; Sagami, H.; Oku, H.; Baba, S.

2018-03-01

This present study describesthe bioinformatics approach to analyze three partial polyprenol reductase genes from mangrove plant, Kandeliaobovataas well aspredictedphysical and chemical properties, potential peptide, subcellular localization, and phylogenetic. The diversity was noted in the physical and chemical properties of three partial polyprenol reductase genes. The values of chloroplast were relatively high, showed that chloroplast transit peptide occurred in mangrove polyprenol reductase. The target peptide value of mitochondria varied from 0.088 to 0.198 indicated it was possible to be present. These results suggested the importance of understanding the diversity of physicochemical properties of the different amino acids in polyprenol reductase. The subcellular localization of two partial genes located in the plasma membrane. To confirm the homology among the polyprenol reductase in the database, a dendrogram was drawn. The phylogenetic tree depicts that there are three clusters, the partial genes of K. obovata joined the largest one: C23157 was close to Ricinus communis polyprenol reductase. Whereas, C23901 and C24171 were grouped with Ipomoea nil polyprenol reductase, suggested that these polyprenol reductase genes form distinct separation into tropical habitat plants.

Recominant Pinoresino-Lariciresinol Reductase, Recombinant Dirigent Protein And Methods Of Use

Science.gov (United States)

Lewis, Norman G.; Davin, Laurence B.; Dinkova-Kostova, Albena T.; Fujita, Masayuki , Gang; David R. , Sarkanen; Simo , Ford; Joshua D.

2003-10-21

Dirigent proteins and pinoresinol/lariciresinol reductases have been isolated, together with cDNAs encoding dirigent proteins and pinoresinol/lariciresinol reductases. Accordingly, isolated DNA sequences are provided from source species Forsythia intermedia, Thuja plicata, Tsuga heterophylla, Eucommia ulmoides, Linum usitatissimum, and Schisandra chinensis, which code for the expression of dirigent proteins and pinoresinol/lariciresinol reductases. In other aspects, replicable recombinant cloning vehicles are provided which code for dirigent proteins or pinoresinol/lariciresinol reductases or for a base sequence sufficiently complementary to at least a portion of dirigent protein or pinoresinol/lariciresinol reductase DNA or RNA to enable hybridization therewith. In yet other aspects, modified host cells are provided that have been transformed, transfected, infected and/or injected with a recombinant cloning vehicle and/or DNA sequence encoding dirigent protein or pinoresinol/lariciresinol reductase. Thus, systems and methods are provided for the recombinant expression of dirigent proteins and/or pinoresinol/lariciresinol reductases.

Simultaneous removal of perchlorate and arsenate by ion-exchange media modified with nanostructured iron (hydr)oxide

Energy Technology Data Exchange (ETDEWEB)

Hristovski, Kiril [Environmental Technology Laboratory, Arizona State University, 6075 S. WMS Campus Loop W, Mesa, AZ 85212 (United States)], E-mail: kiril.hristovski@asu.edu; Westerhoff, Paul [Department of Civil and Environmental Engineering, Arizona State University, Box 5306, Tempe, AZ 85287-5306 (United States)], E-mail: p.westerhoff@asu.edu; Moeller, Teresia [SolmeteX Inc., 50 Bearfoot Road, Northborough, MA 01532 (United States)], E-mail: tmoller@solmetex.com; Sylvester, Paul [SolmeteX Inc., 50 Bearfoot Road, Northborough, MA 01532 (United States)], E-mail: psylvester@solmetex.com; Condit, Wendy [Battelle, 505 King Avenue, Columbus, OH 43201 (United States)], E-mail: conditw@battelle.org; Mash, Heath [United States Environmental Protection Agency, 26W. Martin Luther King Dr., Cincinnati, OH 45268 (United States)], E-mail: mash.heath@epa.gov

2008-03-21

Hybrid ion-exchange (HIX) media for simultaneous removal of arsenate and perchlorate were prepared by impregnation of non-crystalline iron (hydr)oxide nanoparticles onto strong base ion-exchange (IX) resins using two different chemical treatment techniques. In situ precipitation of Fe(III) (M treatment) resulted in the formation of sphere-like clusters of nanomaterials with diameters of {approx}5 nm, while KMnO{sub 4}/Fe(II) treatments yielded rod-like nanomaterials with diameters of 10-50 nm inside the pores of the media. The iron content of most HIX media was >10% of dry weight. The HIX media prepared via the M treatment method consistently exhibited greater arsenate adsorption capacity. The fitted Freundlich adsorption intensity parameters (q=KxC{sub E}{sup 1/n}) for arsenate (1/n < 0.6) indicated favorable adsorption trends. The K values ranged between 2.5 and 34.7 mgAs/g dry resin and were generally higher for the M treated media in comparison to the permanganate treated media. The separation factors for perchlorate over chloride ({alpha}{sub Cl{sup -}}{sup ClO{sub 4}{sup -}}) for the HIX media were lower than its untreated counterparts. The HIX prepared via the M treatment, had higher {alpha}{sub Cl{sup -}}{sup ClO{sub 4}{sup -}} than the HIX obtained by the KMnO{sub 4}/Fe(II) treatments suggesting that permanganate may adversely impact the ion-exchange base media. Short bed adsorber (SBA) tests demonstrated that the mass transport kinetics for both ions are adequately rapid to permit simultaneous removal using HIX media in a fixed bed reactor.

Photometric titration of arsenate with thorium nitrate on the microgram and milligram scale

International Nuclear Information System (INIS)

Harzdorf, C.; Fallah-Tafti, G.

1976-01-01

A method is decribed for the photometric titration of arsenate with thorium nitrate using pyrocatecholviolet as indicator. The method works at a low pH level and is therefore not subject to the most cationic interferences. Alkali salts do not affect the determination even at high concentrations if present as halides, nitrates or perchlorates. This makes the method particularly suitable for the analysis of arsenic in organic and inorganic compounds after decomposition. (orig.) [de

Characterization of arsenic resistant bacteria from arsenic rich groundwater of West Bengal, India.

Science.gov (United States)

Sarkar, Angana; Kazy, Sufia K; Sar, Pinaki

2013-03-01

Sixty-four arsenic (As) resistant bacteria isolated from an arsenic rich groundwater sample of West Bengal were characterized to investigate their potential role in subsurface arsenic mobilization. Among the isolated strains predominance of genera Agrobacterium/Rhizobium, Ochrobactrum and Achromobacter which could grow chemolitrophically and utilize arsenic as electron donor were detected. Higher tolerance to As(3+) [maximum tolerable concentration (MTC): ≥10 mM], As(5+) (MTC: ≥100 mM) and other heavy metals like Cu(2+), Cr(2+), Ni(2+) etc. (MTC: ≥10 mM), presence of arsenate reductase and siderophore was frequently observed among the isolates. Ability to produce arsenite oxidase and phosphatase enzyme was detected in 50 and 34 % of the isolates, respectively. Although no direct correlation among taxonomic identity of bacterial strains and their metabolic abilities as mentioned above was apparent, several isolates affiliated to genera Ochrobactrum, Achromobacter and unclassified Rhizobiaceae members were found to be highly resistant to As(3+) and As(5+) and positive for all the test properties. Arsenate reductase activity was found to be conferred by arsC gene, which in many strains was coupled with arsenite efflux gene arsB as well. Phylogenetic incongruence between the 16S rRNA and ars genes lineages indicated possible incidence of horizontal gene transfer for ars genes. Based on the results we propose that under the prevailing low nutrient condition inhabitant bacteria capable of using inorganic electron donors play a synergistic role wherein siderophores and phosphatase activities facilitate the release of sediment bound As(5+), which is subsequently reduced by arsenate reductase resulting into the mobilization of As(3+) in groundwater.

Sucrose mimics the light induction of Arabidopsis nitrate reductase gene transcription

DEFF Research Database (Denmark)

Cheng, Chi-Lien; Acedo, Gregoria N; Kristensen, Michael

1992-01-01

can replace light in eliciting an increase of nitrate reductase mRNA accumulation in dark-adapted green Arabidopsis plants. We show further that sucrose alone is sufficient for the full expression of nitrate reductase genes in etiolated Arabidopsis plants. Finally, using a reporter gene, we show......Nitrate reductase, the first enzyme in nitrate assimilation, is located at the crossroad of two energy-consuming pathways: nitrate assimilation and carbon fixation. Light, which regulates the expression of many higher-plant carbon fixation genes, also regulates nitrate reductase gene expression....... Located in the cytosol, nitrate reductase obtains its reductant not from photosynthesis but from carbohydrate catabolism. This relationship prompted us to investigate the indirect role that light might play, via photosynthesis, in the regulation of nitrate reductase gene expression. We show that sucrose...

Arsenate and Arsenite Sorption on Magnetite: Relations to Groundwater Arsenic Treatment Using Zerovalent Iron and Natural Attenuation

Science.gov (United States)

Magnetite (Fe3O4) is a zerovalent iron corrosion product; it is also formed in natural soil and sediment. Sorption of arsenate (As(V)) and arsenite (As(III)) on magnetite is an important process of arsenic removal from groundwater using zerovalent iron-based permeable reactive ba...

Rapid microwave-assisted acid extraction of metals from chromated copper arsenate (CCA)-treated southern pine wood

Science.gov (United States)

Bin Yu; Chung Y. Hse; Todd F. Shupe

2009-01-01

The effects of acid concentration, reaction time, and temperature in a microwave reactor on recovery of CCA-treated wood were evaluated. Extraction of copper, chromium, and arsenic metals from chromated copper arsenate (CCA)-treated southern pine wood samples with three different acids (i.e., acetic acid, oxalic acid, and phosphoric acid) was investigated using in...

Cloning and nitrate induction of nitrate reductase mRNA

OpenAIRE

Cheng, Chi-Lien; Dewdney, Julia; Kleinhofs, Andris; Goodman, Howard M.

1986-01-01

Nitrate is the major source of nitrogen taken from the soil by higher plants but requires reduction to ammonia prior to incorporation into amino acids. The first enzyme in the reducing pathway is a nitrate-inducible enzyme, nitrate reductase (EC 1.6.6.1). A specific polyclonal antiserum raised against purified barley nitrate reductase has been used to immunoprecipitate in vivo labeled protein and in vitro translation products, demonstrating that nitrate induction increases nitrate reductase p...

5α-reductase activity in rat adipose tissue

International Nuclear Information System (INIS)

Zyirek, M.; Flood, C.; Longcope, C.

1987-01-01

We measured the 5 α-reductase activity in isolated cell preparations of rat adipose tissue using the formation of [ 3 H] dihydrotestosterone from [ 3 H] testosterone as an endpoint. Stromal cells were prepared from the epididymal fat pad, perinephric fat, and subcutaneous fat of male rats and from perinephric fat of female rats. Adipocytes were prepared from the epididymal fat pad and perinephric fat of male rats. Stromal cells from the epididymal fat pad and perinephric fat contained greater 5α-reductase activity than did the adipocytes from these depots. Stromal cells from the epididymal fat pad contained greater activity than those from perinephric and subcutaneous depots. Perinephric stromal cells from female rats were slightly more active than those from male rats. Estradiol (10 -8 M), when added to the medium, caused a 90% decrease in 5α-reductase activity. Aromatase activity was minimal, several orders of magnitude less than 5α-reductase activity in each tissue studied

Characterization of mitochondrial thioredoxin reductase from C. elegans

International Nuclear Information System (INIS)

Lacey, Brian M.; Hondal, Robert J.

2006-01-01

Thioredoxin reductase catalyzes the NADPH-dependent reduction of the catalytic disulfide bond of thioredoxin. In mammals and other higher eukaryotes, thioredoxin reductases contain the rare amino acid selenocysteine at the active site. The mitochondrial enzyme from Caenorhabditis elegans, however, contains a cysteine residue in place of selenocysteine. The mitochondrial C. elegans thioredoxin reductase was cloned from an expressed sequence tag and then produced in Escherichia coli as an intein-fusion protein. The purified recombinant enzyme has a k cat of 610 min -1 and a K m of 610 μM using E. coli thioredoxin as substrate. The reported k cat is 25% of the k cat of the mammalian enzyme and is 43-fold higher than a cysteine mutant of mammalian thioredoxin reductase. The enzyme would reduce selenocysteine, but not hydrogen peroxide or insulin. The flanking glycine residues of the GCCG motif were mutated to serine. The mutants improved substrate binding, but decreased the catalytic rate

Dietary sources of aldose reductase inhibitors: prospects for alleviating diabetic complications.

Science.gov (United States)

Saraswat, Megha; Muthenna, P; Suryanarayana, P; Petrash, J Mark; Reddy, G Bhanuprakash

2008-01-01

Activation of polyol pathway due to increased aldose reductase activity is one of the several mechanisms that have been implicated in the development of various secondary complications of diabetes. Though numerous synthetic aldose reductase inhibitors have been tested, these have not been very successful clinically. Therefore, a number of common plant/ natural products used in Indian culinary have been evaluated for their aldose reductase inhibitory potential in the present study. The aqueous extracts of 22 plant-derived materials were prepared and evaluated for the inhibitory property against rat lens and human recombinant aldose reductase. Specificity of these extracts towards aldose reductase was established by testing their ability to inhibit a closely related enzyme viz, aldehyde reductase. The ex vivo incubation of erythrocytes in high glucose containing medium was used to underscore the significance in terms of prevention of intracellular sorbitol accumulation. Among the 22 dietary sources tested, 10 showed considerable inhibitory potential against both rat lens and human recombinant aldose reductase. Prominent inhibitory property was found in spinach, cumin, fennel, lemon, basil and black pepper with an approximate IC50 of 0.2 mg/mL with an excellent selectivity towards aldose reductase. As against this, 10 to 20 times higher concentrations were required for 50% inhibition of aldehyde reductase. Reduction in the accumulation of intracellular sorbitol by the dietary extracts further substantiated their in vivo efficacy. The findings reported here indicate the scope of adapting life-style modifications in the form of inclusion of certain common sources in the diet for the management of diabetic complications.

5α-reductases in human physiology: an unfolding story.

Science.gov (United States)

Traish, Abdulmaged M

2012-01-01

5α-reductases are a family of isozymes expressed in a wide host of tissues including the central nervous system (CNS) and play a pivotal role in male sexual differentiation, development and physiology. A comprehensive literature search from 1970 to 2011 was made through PubMed and the relevant information was summarized. 5α reductases convert testosterone, progesterone, deoxycorticosterone, aldosterone and corticosterone into their respective 5α-dihydro-derivatives, which serve as substrates for 3α-hydroxysteroid dehydrogenase enzymes. The latter transforms these 5α-reduced metabolites into a subclass of neuroactive steroid hormones with distinct physiological functions. The neuroactive steroid hormones modulate a multitude of functions in human physiology encompassing regulation of sexual differentiation, neuroprotection, memory enhancement, anxiety, sleep and stress, among others. In addition, 5α -reductase type 3 is also implicated in the N-glycosylation of proteins via formation of dolichol phosphate. The family of 5α-reductases was targeted for drug development to treat pathophysiological conditions, such as benign prostatic hyperplasia and androgenetic alopecia. While the clinical use of 5α-reductase inhibitors was well established, the scope and the magnitude of the adverse side effects of such drugs, especially on the CNS, is still unrecognized due to lack of knowledge of the various physiological functions of this family of enzymes, especially in the CNS. There is an urgent need to better understand the function of 5α-reductases and the role of neuroactive steroids in human physiology in order to minimize the potential adverse side effects of inhibitors targeting 5α-reductases to treat benign prostatic hyperplasia and androgenic alopecia.

Histochemical Localization of Glutathione Dependent NBT-Reductase in Mouse Skin

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

Objective　Localization of the glutathione dependent Nitroblue tetrazolium (NBT) reductase in fresh frozen sections of mouse skin and possible dependence of NBT reductase on tissue thiol levels has been investigated. Methods　The fresh frozen tissue sections (8m thickness) were prepared and incubated in medium containing NBT, reduced glutathione (GSH) and phosphate buffer. The staining for GSH was performed with mercury orange. Results　 The activity of the NBT-reductase in mouse skin has been found to be localized in the areas rich in glutathione and actively proliferating area of the skin. Conclusion　The activity of the NBT-reductase seems to be dependent on the glutathione contents.

Crystallization and diffraction analysis of thioredoxin reductase from Streptomyces coelicolor

International Nuclear Information System (INIS)

Koháryová, Michaela; Brynda, Jiří; Řezáčová, Pavlína; Kollárová, Marta

2011-01-01

Thioredoxin reductase from S. coelicolor was crystallized and diffraction data were collected to 2.4 Å resolution. Thioredoxin reductases are homodimeric flavoenzymes that catalyze the transfer of electrons from NADPH to oxidized thioredoxin substrate. Bacterial thioredoxin reductases represent a promising target for the development of new antibiotics. Recombinant thioredoxin reductase TrxB from Streptomyces coelicolor was crystallized using the hanging-drop vapour-diffusion method. X-ray diffraction data were collected from cryocooled crystals to 2.4 Å resolution using a synchrotron-radiation source. The crystals belonged to the primitive monoclinic space group P2 1 , with unit-cell parameters a = 82.9, b = 60.6, c = 135.4 Å, α = γ = 90.0, β = 96.5°

Light Sensitivity of Lactococcus lactis Thioredoxin Reductase

DEFF Research Database (Denmark)

Skjoldager, Nicklas

The thioredoxin system has evolved in all kingdoms of life acting as a key antioxidant system in the defense against oxidative stress. The thioredoxin system utilizes reducing equivalents from NADPH to reduce protein disulfide targets. The reducing equivalents are shuttled via a flavin and redox...... active dithiol motif in thioredoxin reductase (TrxR) to reduce the small ubiquitous thioredoxin (Trx). Trx in turn regulates the protein dithiol/disulfide balance by reduction of protein disulfide targets in e.g. ribonucleotide reductase, peroxiredoxins and methionine sulfoxide reductase. The glutathione......, thus expected to rely mainly on the Trx system for thiol-disulfide control. L. lactis is an important industrial microorganism used as starter culture in the dairy production of cheese, buttermilk etc. and known to be sensitive to oxidative stress. The L. lactis TrxR (LlTrxR) is a homodimeric...

Evidence that steroid 5alpha-reductase isozyme genes are differentially methylated in human lymphocytes.

Science.gov (United States)

Rodríguez-Dorantes, M; Lizano-Soberón, M; Camacho-Arroyo, I; Calzada-León, R; Morimoto, S; Téllez-Ascencio, N; Cerbón, M A

2002-03-01

The synthesis of dihydrotestosterone (DHT) is catalyzed by steroid 5alpha-reductase isozymes 1 and 2, and this function determines the development of the male phenotype during embriogenesis and the growth of androgen sensitive tissues during puberty. The aim of this study was to determine the cytosine methylation status of 5alpha-reductase isozymes types 1 and 2 genes in normal and in 5alpha-reductase deficient men. Genomic DNA was obtained from lymphocytes of both normal subjects and patients with primary 5alpha-reductase deficiency due to point mutations in 5alpha-reductase 2 gene. Southern blot analysis of 5alpha-reductase types 1 and 2 genes from DNA samples digested with HpaII presented a different cytosine methylation pattern compared to that observed with its isoschizomer MspI, indicating that both genes are methylated in CCGG sequences. The analysis of 5alpha-reductase 1 gene from DNA samples digested with Sau3AI and its isoschizomer MboI which recognize methylation in GATC sequences showed an identical methylation pattern. In contrast, 5alpha-reductase 2 gene digested with Sau3AI presented a different methylation pattern to that of the samples digested with MboI, indicating that steroid 5alpha-reductase 2 gene possess methylated cytosines in GATC sequences. Analysis of exon 4 of 5alpha-reductase 2 gene after metabisulfite PCR showed that normal and deficient subjects present a different methylation pattern, being more methylated in patients with 5alpha-reductase 2 mutated gene. The overall results suggest that 5alpha-reductase genes 1 and 2 are differentially methylated in lymphocytes from normal and 5alpha-reductase deficient patients. Moreover, the extensive cytosine methylation pattern observed in exon 4 of 5alpha-reductase 2 gene in deficient patients, points out to an increased rate of mutations in this gene.

Bacteria, hypertolerant to arsenic in the rocks of an ancient gold mine, and their potential role in dissemination of arsenic pollution.

Science.gov (United States)

Drewniak, Lukasz; Styczek, Aleksandra; Majder-Lopatka, Malgorzata; Sklodowska, Aleksandra

2008-12-01

The aim of the present study was to find out if bacteria present in ancient gold mine could transform immobilized arsenic into its mobile form and increase its dissemination in the environment. Twenty-two arsenic-hypertolerant cultivable bacterial strains were isolated. No chemolithoautotrophs, which could use arsenite as an electron donor as well as arsenate as an electron acceptor, were identified. Five isolates exhibited hypertolerance to arsenic: up to 500mM of arsenate. A correlation between the presence of siderophores and high resistance to arsenic was found. The results of this study show that detoxification processes based on arsenate reductase activity might be significant in dissemination of arsenic pollution. It was concluded that the activity of the described heterotrophic bacteria contributes to the mobilization of arsenic in the more toxic As(III) form and a new mechanism of arsenic mobilization from a scorodite was proposed.

The role of biliverdin reductase in colorectal cancer

International Nuclear Information System (INIS)

Bauer, M.

2010-01-01

In recent years, the effects of biliverdin and bilirubin have been studied extensively, and an inhibitory effect of bile pigments in cancer progression has been proposed. In this study we focused on the effects of biliverdin reductase, the enzyme that converts biliverdin to bilirubin, in colorectal cancer. For in vitro experiments we used a human colorectal carcinoma cell line and transfected it with an expression construct of shRNA specific for biliverdin reductase, to create cells with stable knock-down of enzyme expression. Cell proliferation was analyzed using the CASY model TT cell counting device. Western blot protein analysis was performed to study intracellular signaling cascades. Samples of human colorectal cancer were analyzed using immunohistochemistry. We were able to confirm the antiproliferative effects of bile pigments on cancer cells in vitro. However, this effect was attenuated in biliverdin reductase knock down cells. ERK and Akt activation seen under biliverdin and bilirubin treatment was also reduced in biliverdin reductase deficient cells. Immunohistochemical analysis of tumor samples from patients with colorectal cancer showed elevated biliverdin reductase levels. High enzyme expression was associated with lower overall and disease free patient survival. We conclude that BVR is required for bile pigment mediated effects regarding cancer cell proliferation and modulation of intracellular signaling cascades. The role of BVR overexpression in vivo and its exact influence on cancer progression and patient survival need to be further investigated. (author) [de

Na3Co2(AsO4(As2O7: a new sodium cobalt arsenate

Directory of Open Access Journals (Sweden)

Abderrahmen Guesmi

2012-07-01

Full Text Available In the title compound, trisodium dicobalt arsenate diarsenate, Na3Co2AsO4As2O7, the two Co atoms, one of the two As and three of the seven O atoms lie on special positions, with site symmetries 2 and m for the Co, m for the As, and 2 and twice m for the O atoms. The two Na atoms are disordered over two general and special positions [occupancies 0.72 (3:0.28 (3 and 0.940 (6:0.060 (6, respectively]. The main structural feature is the association of the CoO6 octahedra in the ab plane, forming Co4O20 units, which are corner- and edge-connected via AsO4 and As2O7 arsenate groups, giving rise to a complex polyhedral connectivity with small tunnels, such as those running along the b- and c-axis directions, in which the Na+ ions reside. The structural model is validated by both bond-valence-sum and charge-distribution methods, and the distortion of the coordination polyhedra is analyzed by means of the effective coordination number.

Hepatocyte Hyperproliferation upon Liver-Specific Co-disruption of Thioredoxin-1, Thioredoxin Reductase-1, and Glutathione Reductase

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Justin R. Prigge

2017-06-01

Full Text Available Energetic nutrients are oxidized to sustain high intracellular NADPH/NADP+ ratios. NADPH-dependent reduction of thioredoxin-1 (Trx1 disulfide and glutathione disulfide by thioredoxin reductase-1 (TrxR1 and glutathione reductase (Gsr, respectively, fuels antioxidant systems and deoxyribonucleotide synthesis. Mouse livers lacking both TrxR1 and Gsr sustain these essential activities using an NADPH-independent methionine-consuming pathway; however, it remains unclear how this reducing power is distributed. Here, we show that liver-specific co-disruption of the genes encoding Trx1, TrxR1, and Gsr (triple-null causes dramatic hepatocyte hyperproliferation. Thus, even in the absence of Trx1, methionine-fueled glutathione production supports hepatocyte S phase deoxyribonucleotide production. Also, Trx1 in the absence of TrxR1 provides a survival advantage to cells under hyperglycemic stress, suggesting that glutathione, likely via glutaredoxins, can reduce Trx1 disulfide in vivo. In triple-null livers like in many cancers, deoxyribonucleotide synthesis places a critical yet relatively low-volume demand on these reductase systems, thereby favoring high hepatocyte turnover over sustained hepatocyte integrity.

Kinetics of carbonyl reductase from human brain.

OpenAIRE

Bohren, K M; von Wartburg, J P; Wermuth, B

1987-01-01

Initial-rate analysis of the carbonyl reductase-catalysed reduction of menadione by NADPH gave families of straight lines in double-reciprocal plots consistent with a sequential mechanism being obeyed. The fluorescence of NADPH was increased up to 7-fold with a concomitant shift of the emission maximum towards lower wavelength in the presence of carbonyl reductase, and both NADPH and NADP+ caused quenching of the enzyme fluorescence, indicating formation of a binary enzyme-coenzyme complex. D...

Assessment of the environmental effects associated with wooden bridges preserved with creosote, pentachlorophenol, or chromated copper arsenate

Science.gov (United States)

Kenneth M. Brooks

Timber bridges provide an economical alternative to concrete and steel structures, particularly in rural areas with light to moderate vehicle traffic. Wooden components of these bridges are treated with chromated copper arsenate type C (CCA), pentachlorophenol, or creosote to prolong the life of the structure from a few years to many decades. This results in reduced...

TISSUE DISTRIBUTION OF INORGANIC ARSENIC (AS) AND ITS METHYLATED METABOLITES IN MICE FOLLOWING ORAL ADMINISTRATION OF ARSENATE (ASV)

Science.gov (United States)

TISSUE DISTRIBUTION OF INORGANIC ARSENIC (iAs) AND ITS METHYLATED METABOLITES IN MICE FOLLOWING ORAL ADMINISTRATION OF ARSENATE (AsV). E M Kenyon1, L M Del Razo2, and M F Hughes1. 1NHEERL, ORD, US EPA, RTP, NC, USA; 2CINVESTAV-IPN, Mexico City, Mexico.The relationship o...

Nitrate reductase activity and its relationship with applied nitrogen in soybean

International Nuclear Information System (INIS)

Ge Wenting; Jin Xijun; Ma Chunmei; Dong Shoukun; Gong Zhenping; Zhang Lei

2011-01-01

Field experiments were conducted to study the nitrate reductase activity and its relationship to nitrogen by using frame tests (pot without bottom), sand culture and 15 N-urea at transplanting in soybean variety Suinong 14. Results showed that the activity of nitrate reductase in leaf changed as a signal peak curve with the soybean growth, lower in vegetative growth phase, higher in reproductive growth period and reached the peak in blooming period, then decreased gradually. Nitrogen application showed obvious effect on the nitrate reductase activity. The activities of nitrate reductase in leaves followed the order of N 135 > N 90 > N 45 > N 0 in vegetative growth stage, no clear regularity was found during the whole reproductive growth period. The activities of nitrate reductase in leaves were accorded with the order of upper leaves > mid leaves > lower leaves, and it was very significant differences (P 15 N labeling method during beginning seed stage and full seed stage shown that 15 N abundance in various organs at different node position also followed the same order, suggesting that high level of nitrate reductase activity at upper leaves of soybean promoted the assimilation of NO 3 - . (authors)

Differential expression of disulfide reductase enzymes in a free-living platyhelminth (Dugesia dorotocephala.

Directory of Open Access Journals (Sweden)

Alberto Guevara-Flores

Full Text Available A search of the disulfide reductase activities expressed in the adult stage of the free-living platyhelminth Dugesia dorotocephala was carried out. Using GSSG or DTNB as substrates, it was possible to obtain a purified fraction containing both GSSG and DTNB reductase activities. Through the purification procedure, both disulfide reductase activities were obtained in the same chromatographic peak. By mass spectrometry analysis of peptide fragments obtained after tryptic digestion of the purified fraction, the presence of glutathione reductase (GR, thioredoxin-glutathione reductase (TGR, and a putative thioredoxin reductase (TrxR was detected. Using the gold compound auranofin to selectively inhibit the GSSG reductase activity of TGR, it was found that barely 5% of the total GR activity in the D. dorotocephala extract can be assigned to GR. Such strategy did allow us to determine the kinetic parameters for both GR and TGR. Although It was not possible to discriminate DTNB reductase activity due to TrxR from that of TGR, a chromatofocusing experiment with a D. dorotocephala extract resulted in the obtention of a minor protein fraction enriched in TrxR, strongly suggesting its presence as a functional protein. Thus, unlike its parasitic counterparts, in the free-living platyhelminth lineage the three disulfide reductases are present as functional proteins, albeit TGR is still the major disulfide reductase involved in the reduction of both Trx and GSSG. This fact suggests the development of TGR in parasitic flatworms was not linked to a parasitic mode of life.

Immunological comparison of the NADH:nitrate reductase from different cucumber tissues

Directory of Open Access Journals (Sweden)

Jolanta Marciniak

2014-01-01

Full Text Available Soluble nitrate reductase from cucumber roots (Cucumis sativus L. was isolated and purified with blue-Sepharose 4B. Specific antibodies against the NR protein were raised by immunization of a goat. Using polyclonal antibodies anti-NR properties of the nitrate reductase from various cucumber tissues were examined. Experiments showed difference in immuno-logical properties of nitrate reductase (NR from cotyledon roots and leaves.

Expression and site-directed mutagenesis of human dihydrofolate reductase

Energy Technology Data Exchange (ETDEWEB)

Prendergast, N.J.; Delcamp, T.J.; Smith, P.L.; Freisheim, J.H.

1988-05-17

A procaryotic high-level expression vector for human dihydrofolate reductase has been constructed and the protein characterized as a first step toward structure-function studies of this enzyme. A vector bearing the tac promoter, four synthetic oligodeoxynucleotides, and a restriction fragment from the dihydrofolate reductase cDNA were ligated in a manner which optimized the transcriptional and translational frequency of the enzyme mRNA. The reductase, comprising ca. 17% of the total soluble protein in the host bacteria, was purified to apparent homogeneity as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and characterized by amino acid composition, partial amino acid sequence, and steady-sate kinetic analysis. This expression vector has been used as a template for double-stranded plasmid DNA site-specific mutagenesis. Functional studies on a Cys-6 ..-->.. Ser-6 mutant enzyme support the contention that Cys-6 is obligatory for organomercurial activation of human dihydrofolate reductase. The Ser-6 mutant enzyme was not activated to any extent following a 24-h incubation with p-(hydroxymercuri)benzoate and nicotinamide adenine dinucleotide phosphate (reduced) (NADPH), whereas the k/sub cat/ for Cys-6 reductase increased 2-fold under identical conditions. The specific activities of the Cys-6 and Ser-6 enzymes were virtually identical as determined by methotrexate titration as were the K/sub m/ values for both dihydrofolate and NADPH. The Ser-6 mutant showed a decreased temperature stability and was more sensitive to inactivation by ..cap alpha..-chymotrypsin when compared to the wild-type enzyme. These results suggest that the Ser-6 mutant reductase is conformationally altered relative to the Cys-6 native enzyme.

Expression and site-directed mutagenesis of human dihydrofolate reductase

International Nuclear Information System (INIS)

Prendergast, N.J.; Delcamp, T.J.; Smith, P.L.; Freisheim, J.H.

1988-01-01

A procaryotic high-level expression vector for human dihydrofolate reductase has been constructed and the protein characterized as a first step toward structure-function studies of this enzyme. A vector bearing the tac promoter, four synthetic oligodeoxynucleotides, and a restriction fragment from the dihydrofolate reductase cDNA were ligated in a manner which optimized the transcriptional and translational frequency of the enzyme mRNA. The reductase, comprising ca. 17% of the total soluble protein in the host bacteria, was purified to apparent homogeneity as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and characterized by amino acid composition, partial amino acid sequence, and steady-sate kinetic analysis. This expression vector has been used as a template for double-stranded plasmid DNA site-specific mutagenesis. Functional studies on a Cys-6 → Ser-6 mutant enzyme support the contention that Cys-6 is obligatory for organomercurial activation of human dihydrofolate reductase. The Ser-6 mutant enzyme was not activated to any extent following a 24-h incubation with p-(hydroxymercuri)benzoate and nicotinamide adenine dinucleotide phosphate (reduced) (NADPH), whereas the k/sub cat/ for Cys-6 reductase increased 2-fold under identical conditions. The specific activities of the Cys-6 and Ser-6 enzymes were virtually identical as determined by methotrexate titration as were the K/sub m/ values for both dihydrofolate and NADPH. The Ser-6 mutant showed a decreased temperature stability and was more sensitive to inactivation by α-chymotrypsin when compared to the wild-type enzyme. These results suggest that the Ser-6 mutant reductase is conformationally altered relative to the Cys-6 native enzyme

Metal resistant plants and phytoremediation of environmental contamination

Science.gov (United States)

Meagher, Richard B.; Li, Yujing; Dhankher, Om P.

2010-04-20

The present disclosure provides a method of producing transgenic plants which are resistant to at least one metal ion by transforming the plant with a recombinant DNA comprising a nucleic acid encoding a bacterial arsenic reductase under the control of a plant expressible promoter, and a nucleic acid encoding a nucleotide sequence encoding a phytochelatin biosynthetic enzyme under the control of a plant expressible promoter. The invention also relates a method of phytoremediation of a contaminated site by growing in the site a transgenic plant expressing a nucleic acid encoding a bacterial arsenate reductase and a nucleic acid encoding a phytochelatin biosynthetic enzyme.

Green synthesis and evaluation of an iron-based metal-organic framework MIL-88B for efficient decontamination of arsenate from water.

Science.gov (United States)

Hou, Shuliang; Wu, Yi-Nan; Feng, Lingyu; Chen, Wei; Wang, Ying; Morlay, Catherine; Li, Fengting

2018-02-13

Iron-containing metal-organic frameworks (MOFs) have gradually emerged as environmentally benign alternatives for reducing the levels of environmental contamination because of their advantages, such as readily obtained raw materials with low cost, nontoxic metal source with good biocompatibility, and distinguished physicochemical features e.g., high porosity, framework flexibility, and semiconductor properties. In this study, we reported an innovative strategy for synthesizing an iron-based MOF, MIL-88B, at room temperature. The novelty of this strategy was the use of ethanol as solvent and the pretreatment of dry milling with neither the bulk use of a toxic organic solvent nor the addition of extremely dangerous hydrofluoric acid or strong alkali. The synthesized MIL-88B(Fe) was evaluated as a sorbent for removing arsenate in water and it exhibited high adsorption capacity (156.7 mg g -1 ) at a low dosage. The removal capacity of trace arsenate on MIL-88B(Fe) was 32.3 mg g -1 at a low equilibrium concentration (6.4 μg L -1 ), which satisfied the arsenic threshold for drinking water. The results of Fourier transform infrared and X-ray photoelectron spectroscopy indicated that the As(v) molecules bonded with the oxygen molecules, which were coordinated with FeO clusters in the framework. This work presented the potential use of the up-scaled MIL-88B as an excellent sorbent for purifying arsenate-contaminated water.

Regulation of Small Mitochondrial DNA Replicative Advantage by Ribonucleotide Reductase in Saccharomyces cerevisiae

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Elliot Bradshaw

2017-09-01

Full Text Available Small mitochondrial genomes can behave as selfish elements by displacing wild-type genomes regardless of their detriment to the host organism. In the budding yeast Saccharomyces cerevisiae, small hypersuppressive mtDNA transiently coexist with wild-type in a state of heteroplasmy, wherein the replicative advantage of the small mtDNA outcompetes wild-type and produces offspring without respiratory capacity in >95% of colonies. The cytosolic enzyme ribonucleotide reductase (RNR catalyzes the rate-limiting step in dNTP synthesis and its inhibition has been correlated with increased petite colony formation, reflecting loss of respiratory function. Here, we used heteroplasmic diploids containing wild-type (rho+ and suppressive (rho− or hypersuppressive (HS rho− mitochondrial genomes to explore the effects of RNR activity on mtDNA heteroplasmy in offspring. We found that the proportion of rho+ offspring was significantly increased by RNR overexpression or deletion of its inhibitor, SML1, while reducing RNR activity via SML1 overexpression produced the opposite effects. In addition, using Ex Taq and KOD Dash polymerases, we observed a replicative advantage for small over large template DNA in vitro, but only at low dNTP concentrations. These results suggest that dNTP insufficiency contributes to the replicative advantage of small mtDNA over wild-type and cytosolic dNTP synthesis by RNR is an important regulator of heteroplasmy involving small mtDNA molecules in yeast.

Transformation and characterization of an arsenic gene operon from urease-positive thermophilic Campylobacter (UPTC) in Escherichia coli.

Science.gov (United States)

Matsuda, M; Kuribayashi, T; Yamamoto, S; Millar, B C; Moore, J E

2016-01-01

An arsenate susceptibility test was performed with transformed and cultured Escherichia coli DH5α cells, which carried recombinant DNA of full-length arsenic (ars) operon, namely a putative membrane permease, ArsP; a transcriptional repressor, ArsR; an arsenate reductase, ArsC; and an arsenical-resistance membrane transporter, Acr3, from the Japanese urease-positive thermophilic Campylobacter lari (UPTC) CF89-12. The E. coli DH5α transformant showed reduced susceptibility to arsenate (~1536 μg/mL), compared to the control. Thus, these ars four-genes from the UPTC CF89-12 strain cells could confer a reduced susceptibility to arsenate in the transformed and E. coli DH5α cells. E. coli transformants with truncated ars operons, acr3 (acr3) and arsC-acr3 (∆arsC-acr3), of the ars operon, showed an MIC value of 384 μg/mL (~384 μg/mL), similar to the E. coli cells which carried the pGEM-T vector (control). Reverse transcription PCR confirmed in vivo transcription of recombinant full-length ars operon and deletion variants (∆acr3 and ∆arsC-acr3) in the transformed E. coli cells.

In vivo photoinactivation of Escherichia coli ribonucleoside reductase by near-ultraviolet light

International Nuclear Information System (INIS)

Peters, J.

1977-01-01

Some experimental work is described showing that near-U.V. irradiation of E.coli cells selectively destroys RDP-reductase (ribonucleoside diphosphate reductase) activity in vivo are providing evidence relating the loss of RDP-reductase to loss of cellular visibility and the inactivity of irrdiated cells to support the replication of DNA phages. The data are consistent with the interpretation that the principal cause in the killing of exponentially growing E.coli cells by near-U.V., and the loss of ability of irradiated host cells to support the replication of DNA phages, is the photoinactivation of the RDP-reductase complex. (U.K.)

In vivo photoinactivation of Escherichia coli ribonucleoside reductase by near-ultraviolet light

Energy Technology Data Exchange (ETDEWEB)

Peters, J [California Univ., Irvine (USA)

1977-06-09

Some experimental work is described showing that near-uv irradiation of E.coli cells selectively destroys RDP-reductase (ribonucleoside diphosphate reductase) activity in vivo are providing evidence relating the loss of RDP-reductase to loss of cellular visibility and the inactivity of irrdiated cells to support the replication of DNA phages. The data are consistent with the interpretation that the principal cause in the killing of exponentially growing E.coli cells by near-uv, and the loss of ability of irradiated host cells to support the replication of DNA phages, is the photoinactivation of the RDP-reductase complex.

Developmental consequences of in utero sodium arsenate exposure in mice with folate transport deficiencies

International Nuclear Information System (INIS)

Spiegelstein, Ofer; Gould, Amy; Wlodarczyk, Bogdan; Tsie, Marlene; Lu Xiufen; Le, Chris; Troen, Aron; Selhub, Jacob; Piedrahita, Jorge A.; Salbaum, J. Michael; Kappen, Claudia; Melnyk, Stepan; James, Jill; Finnell, Richard H.

2005-01-01

Previous studies have demonstrated that mice lacking a functional folate binding protein 2 gene (Folbp2 -/- ) were significantly more sensitive to in utero arsenic exposure than were the wild-type mice similarly exposed. When these mice were fed a folate-deficient diet, the embryotoxic effect of arsenate was further exacerbated. Contrary to expectations, studies on 24-h urinary speciation of sodium arsenate did not demonstrate any significant difference in arsenic biotransformation between Folbp2 -/- and Folbp2 +/+ mice. To better understand the influence of folate pathway genes on arsenic embryotoxicity, the present investigation utilized transgenic mice with disrupted folate binding protein 1 (Folbp1) and reduced folate carrier (RFC) genes. Because complete inactivation of Folbp1 and RFC genes results in embryonic lethality, we used heterozygous animals. Overall, no RFC genotype-related differences in embryonic susceptibility to arsenic exposure were observed. Embryonic lethality and neural tube defect (NTD) frequency in Folbp1 mice was dose-dependent and differed from the RFC mice; however, no genotype-related differences were observed. The RFC heterozygotes tended to have higher plasma levels of S-adenosylhomocysteine (SAH) than did the wild-type controls, although this effect was not robust. It is concluded that genetic modifications at the Folbp1 and RFC loci confers no particular sensitivity to arsenic toxicity compared to wild-type controls, thus disproving the working hypothesis that decreased methylating capacity of the genetically modified mice would put them at increased risk for arsenic-induced reproductive toxicity

Inhibition of fumarate reductase in Leishmania major and L. donovani by chalcones

DEFF Research Database (Denmark)

Chen, M; Zhai, L; Christensen, S B

2001-01-01

Our previous studies have shown that chalcones exhibit potent antileishmanial and antimalarial activities in vitro and in vivo. Preliminary studies showed that these compounds destroyed the ultrastructure of Leishmania parasite mitochondria and inhibited the respiration and the activity...... of mitochondrial dehydrogenases of Leishmania parasites. The present study was designed to further investigate the mechanism of action of chalcones, focusing on the parasite respiratory chain. The data show that licochalcone A inhibited the activity of fumarate reductase (FRD) in the permeabilized Leishmania major...... promastigote and in the parasite mitochondria, and it also inhibited solubilized FRD and a purified FRD from L. donovani. Two other chalcones, 2,4-dimethoxy-4'-allyloxychalcone (24m4ac) and 2,4-dimethoxy-4'-butoxychalcone (24mbc), also exhibited inhibitory effects on the activity of solubilized FRD in L. major...

Association between methylenetetrahydrofolate reductase (MTHFR ...

African Journals Online (AJOL)

Association between methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism and risk of ischemic stroke in North Indian population: A hospital based case–control study. Amit Kumar, Shubham Misra, Anjali Hazarika, Pradeep Kumar, Ram Sagar, Abhishek Pathak, Kamalesh Chakravarty, Kameshwar ...

The effect of ionic and non-ionic surfactants on the growth, nitrate reductase and nitrite reductase activities of Spirodela polyrrhiza (L. Schleiden

Directory of Open Access Journals (Sweden)

Józef Buczek

2014-01-01

Full Text Available Inclusion into the medium of 5 mg•dm-3 of non-ionic (ENF or ionic (DBST surfactant caused 50-60% inhibition of nitrite reductase MR activity in S. polyrrhiza. At the same time, increased accumulation of NO2- in the plant tissues and lowering of the total and soluble protein contents were found. DBST also lowered the nitrate reductase (NR activity and the dry mass of the plants.

Expression, purification, crystallization and preliminary X-ray analysis of perakine reductase, a new member of the aldo-keto reductase enzyme superfamily from higher plants

Energy Technology Data Exchange (ETDEWEB)

Rosenthal, Cindy [Department of Pharmaceutical Biology, Institute of Pharmacy, Johannes Gutenberg-University Mainz, Staudinger Weg 5, D-55099 Mainz (Germany); Mueller, Uwe [Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung mbH, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany); Panjikar, Santosh [European Molecular Biology Laboratory Hamburg, Outstation Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22603 Hamburg (Germany); Sun, Lianli [Department of Pharmaceutical Biology, Institute of Pharmacy, Johannes Gutenberg-University Mainz, Staudinger Weg 5, D-55099 Mainz (Germany); Department of TCM and Natural Drug Research, College of Pharmaceutical Sciences, 513 Zijingang Campus, Zhejiang University, 310058 Hangzhou (China); Ruppert, Martin [Department of Pharmaceutical Biology, Institute of Pharmacy, Johannes Gutenberg-University Mainz, Staudinger Weg 5, D-55099 Mainz (Germany); Zhao, Yu [Department of TCM and Natural Drug Research, College of Pharmaceutical Sciences, 513 Zijingang Campus, Zhejiang University, 310058 Hangzhou (China); Stöckigt, Joachim [Department of Pharmaceutical Biology, Institute of Pharmacy, Johannes Gutenberg-University Mainz, Staudinger Weg 5, D-55099 Mainz (Germany); Department of TCM and Natural Drug Research, College of Pharmaceutical Sciences, 513 Zijingang Campus, Zhejiang University, 310058 Hangzhou (China)

2006-12-01

Perakine reductase, a novel member of the aldo-keto reductase enzyme superfamily of higher plants, is involved in the biosynthesis of monoterpenoid indole alkaloids in the Indian medicinal plant Rauvolfia serpentina. The enzyme has been crystallized in C-centered orthorhombic space group and diffracts to 2.0 Å resolution. Perakine reductase (PR) is a novel member of the aldo-keto reductase enzyme superfamily from higher plants. PR from the plant Rauvolfia serpentina is involved in the biosynthesis of monoterpenoid indole alkaloids by performing NADPH-dependent reduction of perakine, yielding raucaffrinoline. However, PR can also reduce cinnamic aldehyde and some of its derivatives. After heterologous expression of a triple mutant of PR in Escherichia coli, crystals of the purified and methylated enzyme were obtained by the hanging-drop vapour-diffusion technique at 293 K with 100 mM sodium citrate pH 5.6 and 27% PEG 4000 as precipitant. Crystals belong to space group C222{sub 1} and diffract to 2.0 Å, with unit-cell parameters a = 58.9, b = 93.0, c = 143.4 Å.

Expression, purification, crystallization and preliminary X-ray analysis of perakine reductase, a new member of the aldo-keto reductase enzyme superfamily from higher plants

International Nuclear Information System (INIS)

Rosenthal, Cindy; Mueller, Uwe; Panjikar, Santosh; Sun, Lianli; Ruppert, Martin; Zhao, Yu; Stöckigt, Joachim

2006-01-01

Perakine reductase, a novel member of the aldo-keto reductase enzyme superfamily of higher plants, is involved in the biosynthesis of monoterpenoid indole alkaloids in the Indian medicinal plant Rauvolfia serpentina. The enzyme has been crystallized in C-centered orthorhombic space group and diffracts to 2.0 Å resolution. Perakine reductase (PR) is a novel member of the aldo-keto reductase enzyme superfamily from higher plants. PR from the plant Rauvolfia serpentina is involved in the biosynthesis of monoterpenoid indole alkaloids by performing NADPH-dependent reduction of perakine, yielding raucaffrinoline. However, PR can also reduce cinnamic aldehyde and some of its derivatives. After heterologous expression of a triple mutant of PR in Escherichia coli, crystals of the purified and methylated enzyme were obtained by the hanging-drop vapour-diffusion technique at 293 K with 100 mM sodium citrate pH 5.6 and 27% PEG 4000 as precipitant. Crystals belong to space group C222 1 and diffract to 2.0 Å, with unit-cell parameters a = 58.9, b = 93.0, c = 143.4 Å

Identification of the 7-Hydroxymethyl Chlorophyll a Reductase of the Chlorophyll Cycle in Arabidopsis[W

Science.gov (United States)

Meguro, Miki; Ito, Hisashi; Takabayashi, Atsushi; Tanaka, Ryouichi; Tanaka, Ayumi

2011-01-01

The interconversion of chlorophyll a and chlorophyll b, referred to as the chlorophyll cycle, plays a crucial role in the processes of greening, acclimation to light intensity, and senescence. The chlorophyll cycle consists of three reactions: the conversions of chlorophyll a to chlorophyll b by chlorophyllide a oxygenase, chlorophyll b to 7-hydroxymethyl chlorophyll a by chlorophyll b reductase, and 7-hydroxymethyl chlorophyll a to chlorophyll a by 7-hydroxymethyl chlorophyll a reductase. We identified 7-hydroxymethyl chlorophyll a reductase, which is the last remaining unidentified enzyme of the chlorophyll cycle, from Arabidopsis thaliana by genetic and biochemical methods. Recombinant 7-hydroxymethyl chlorophyll a reductase converted 7-hydroxymethyl chlorophyll a to chlorophyll a using ferredoxin. Both sequence and biochemical analyses showed that 7-hydroxymethyl chlorophyll a reductase contains flavin adenine dinucleotide and an iron-sulfur center. In addition, a phylogenetic analysis elucidated the evolution of 7-hydroxymethyl chlorophyll a reductase from divinyl chlorophyllide vinyl reductase. A mutant lacking 7-hydroxymethyl chlorophyll a reductase was found to accumulate 7-hydroxymethyl chlorophyll a and pheophorbide a. Furthermore, this accumulation of pheophorbide a in the mutant was rescued by the inactivation of the chlorophyll b reductase gene. The downregulation of pheophorbide a oxygenase activity is discussed in relation to 7-hydroxymethyl chlorophyll a accumulation. PMID:21934147

Effect of weathering on chromated copper arsenate (CCA) treated wood : leaching of metal salts and change in water repellency

Science.gov (United States)

R. Sam Williams; Stan Lebow; Patricia Lebow

2003-01-01

Wood pressure-treated with chromated copper arsenate (CCA) wood preservative is commonly used for outdoor construction. Oxides of arsenic, copper, and chromium are bound in the wood by a complex series of chemical reactions, but a small percentage of these compounds are gradually released by leaching and weathering. Recent studies suggest that the release of these...

Genome sequence analysis of predicted polyprenol reductase gene from mangrove plant kandelia obovata

Science.gov (United States)

Basyuni, M.; Sagami, H.; Baba, S.; Oku, H.

2018-03-01

It has been previously reported that dolichols but not polyprenols were predominated in mangrove leaves and roots. Therefore, the occurrence of larger amounts of dolichol in leaves of mangrove plants implies that polyprenol reductase is responsible for the conversion of polyprenol to dolichol may be active in mangrove leaves. Here we report the early assessment of probably polyprenol reductase gene from genome sequence of mangrove plant Kandelia obovata. The functional assignment of the gene was based on a homology search of the sequences against the non-redundant (nr) peptide database of NCBI using Blastx. The degree of sequence identity between DNA sequence and known polyprenol reductase was confirmed using the Blastx probability E-value, total score, and identity. The genome sequence data resulted in three partial sequences, termed c23157 (700 bp), c23901 (960 bp), and c24171 (531 bp). The c23157 gene showed the highest similarity (61%) to predicted polyprenol reductase 2- like from Gossypium raimondii with E-value 2e-100. The second gene was c23901 to exhibit high similarity (78%) to the steroid 5-alpha-reductase Det2 from J. curcas with E-value 2e-140. Furthermore, the c24171 gene depicted highest similarity (79%) to the polyprenol reductase 2 isoform X1 from Jatropha curcas with E- value 7e-21.The present study suggested that the c23157, c23901, and c24171, genes may encode predicted polyprenol reductase. The c23157, c23901, c24171 are therefore the new type of predicted polyprenol reductase from K. obovata.

Towards a selective adsorbent for arsenate and selenite in the presence of phosphate: Assessment of adsorption efficiency, mechanism, and binary separation factors of the chitosan-copper complex.

Science.gov (United States)

Yamani, Jamila S; Lounsbury, Amanda W; Zimmerman, Julie B

2016-01-01

The potential for a chitosan-copper polymer complex to select for the target contaminants in the presence of their respective competitive ions was evaluated by synthesizing chitosan-copper beads (CCB) for the treatment of (arsenate:phosphate), (selenite:phosphate), and (selenate:sulfate). Based on work by Rhazi et al., copper (II) binds to the amine moiety on the chitosan backbone as a monodentate complex (Type I) and as a bidentate complex crosslinking two polymer chains (Type II), depending on pH and copper loading. In general, the Type I complex exists alone; however, beyond threshold conditions of pH 5.5 during synthesis and a copper loading of 0.25 mol Cu(II)/mol chitosan monomer, the Type I and Type II complexes coexist. Subsequent chelation of this chitosan-copper ligand to oxyanions results in enhanced and selective adsorption of the target contaminants in complex matrices with high background ion concentrations. With differing affinities for arsenate, selenite, and phosphate, the Type I complex favors phosphate chelation while the Type II complex favors arsenate chelation due to electrostatic considerations and selenite chelation due to steric effects. No trend was exhibited for the selenate:sulfate system possibly due to the high Ksp of the corresponding copper salts. Binary separation factors, α12, were calculated for the arsenate-phosphate and selenite-phosphate systems, supporting the mechanistic hypothesis. While, further research is needed to develop a synthesis method for the independent formation of the Type II complexes to select for target contaminants in complex matrices, this work can provide initial steps in the development of a selective adsorbent. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sucrose mimics the light induction of Arabidopsis nitrate reductase gene transcription

DEFF Research Database (Denmark)

Cheng, Chi-Lien; Acedo, Gregoria N; Kristensen, Michael

1992-01-01

Nitrate reductase, the first enzyme in nitrate assimilation, is located at the crossroad of two energy-consuming pathways: nitrate assimilation and carbon fixation. Light, which regulates the expression of many higher-plant carbon fixation genes, also regulates nitrate reductase gene expression. ...

Separation/Preconcentration and Speciation Analysis of Trace Amounts of Arsenate and Arsenite in Water Samples Using Modified Magnetite Nanoparticles and Molybdenum Blue Method

Directory of Open Access Journals (Sweden)

Mohammad Ali Karimi

2014-01-01

Full Text Available A new, simple, and fast method for the separation/preconcentration and speciation analysis of arsenate and arsenite ions using cetyltrimethyl ammonium bromide immobilized on alumina-coated magnetite nanoparticles (CTAB@ACMNPs followed by molybdenum blue method is proposed. The method is based on the adsorption of arsenate on CTAB@ACMNPs. Total arsenic in different samples was determined as As(V after oxidation of As(III to As(V using potassium permanganate. The arsenic concentration has been determined by UV-Visible spectrometric technique based on molybdenum blue method and amount of As(III was calculated by subtracting the concentration of As(V from total arsenic concentration. MNPs and ACMNPs were characterized by VSM, XRD, SEM, and FT-IR spectroscopy. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range, and relative standard deviation (RSD of arsenate were 175 (for 350 mL of sample solution, 0.028 μg mL−1, 0.090–4.0 μg mL−1, and 2.8% (for 2.0 μg mL−1, n=7, respectively. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. The proposed method was successfully applied to the determination and speciation of arsenic in different water samples and suitable recoveries were obtained.

New Insight into the Local Structure of Hydrous Ferric Arsenate Using Full-Potential Multiple Scattering Analysis, Density Functional Theory Calculations, and Vibrational Spectroscopy.

Science.gov (United States)

Wang, Shaofeng; Ma, Xu; Zhang, Guoqing; Jia, Yongfeng; Hatada, Keisuke

2016-11-15

Hydrous ferric arsenate (HFA) is an important arsenic-bearing precipitate in the mining-impacted environment and hydrometallurgical tailings. However, there is no agreement on its local atomic structure. The local structure of HFA was reprobed by employing a full-potential multiple scattering (FPMS) analysis, density functional theory (DFT) calculations, and vibrational spectroscopy. The FPMS simulations indicated that the coordination number of the As-Fe, Fe-As, or both in HFA was approximately two. The DFT calculations constructed a structure of HFA with the formula of Fe(HAsO 4 ) x (H 2 AsO 4 ) 1-x (OH) y ·zH 2 O. The presence of protonated arsenate in HFA was also evidenced by vibrational spectroscopy. The As and Fe K-edge X-ray absorption near-edge structure spectra of HFA were accurately reproduced by FPMS simulations using the chain structure, which was also a reasonable model for extended X-Ray absorption fine structure fitting. The FPMS refinements indicated that the interatomic Fe-Fe distance was approximately 5.2 Å, consistent with that obtained by Mikutta et al. (Environ. Sci. Technol. 2013, 47 (7), 3122-3131) using wavelet analysis. All of the results suggested that HFA was more likely to occur as a chain with AsO 4 tetrahedra and FeO 6 octahedra connecting alternately in an isolated bidentate-type fashion. This finding is of significance for understanding the fate of arsenic and the formation of ferric arsenate minerals in an acidic environment.

Bioinformatics analysis of the predicted polyprenol reductase genes in higher plants

Science.gov (United States)

Basyuni, M.; Wati, R.

2018-03-01

The present study evaluates the bioinformatics methods to analyze twenty-four predicted polyprenol reductase genes from higher plants on GenBank as well as predicted the structure, composition, similarity, subcellular localization, and phylogenetic. The physicochemical properties of plant polyprenol showed diversity among the observed genes. The percentage of the secondary structure of plant polyprenol genes followed the ratio order of α helix > random coil > extended chain structure. The values of chloroplast but not signal peptide were too low, indicated that few chloroplast transit peptide in plant polyprenol reductase genes. The possibility of the potential transit peptide showed variation among the plant polyprenol reductase, suggested the importance of understanding the variety of peptide components of plant polyprenol genes. To clarify this finding, a phylogenetic tree was drawn. The phylogenetic tree shows several branches in the tree, suggested that plant polyprenol reductase genes grouped into divergent clusters in the tree.

Hepatoprotective effects of hexane root extract of Alchornea laxiflora in sodium arsenate toxicity in wistar albino rats

OpenAIRE

Esosa Samuel Uhunmwangho; Nurudeen Olajide Rasaq; Iyanuoluwa Olubukola Osikoya

2018-01-01

Background: Medicinal plants are have been used in the treatment of myriad disease conditions, Alchornea laxiflora is one of such medicinal plant. Aim: To investigate the hepatoprotective effect of hexane root extract of Alchornea laxiflora against sodium arsenate induced liver damage in wistar male rats. Setting and Design: Extraction and administration of bioactive extract. Materials and Methods: Extraction of air-dried ground root of Alchornea laxiflora was done by extracting 500 g with 50...

Fractionation of heavy metals in liquefied chromated copper arsenate (CCA)-treated wood sludge using a modified BCR-sequential extraction procedure

Science.gov (United States)

Hui Pan; Chung-Yun Hse; Robert Gambrell; Todd F. Shupe

2009-01-01

Chromated copper arsenate (CCA)-treated wood was liquefied with polyethylene glycol/glycerin and sulfuric acid. After liquefaction, most CCA metals (98% As, 92% Cr, and 83% Cu) were removed from liquefied CCA-treated wood by precipitation with calcium hydroxide. The original CCA-treated wood and liquefied CCA-treated wood sludge were fractionated by a modified...

Rapid microwave-assisted acid extraction of southern pine waste wood to remove metals from chromated copper arsenate (CCA) treatment

Science.gov (United States)

Chung-Yun Hse; Todd F. Shupe; Bin Yu

2013-01-01

Recovery of metals from chromated copper arsenate (CCA)-treated southern pine wood particles was investigated by extraction in a microwave reactor with binary combinations of acetic acid (AA), oxalic acid (OxA), and phosphoric acid (PhA). Use of OxA was not successful, as insoluble copper oxalate complexes impeded copper removal. The combination of OxA and AA also had...

Respiratory guiding system for respiratory motion management in respiratory gated radiotherapy

International Nuclear Information System (INIS)

Kang, Seong Hee; Kim, Dong Su; Kim, Tae Ho; Suh, Tae Suk

2013-01-01

Respiratory guiding systems have been shown to improve the respiratory regularity. This, in turn, improves the efficiency of synchronized moving aperture radiation therapy, and it reduces the artifacts caused by irregular breathing in imaging techniques such as four-dimensional computed tomography (4D CT), which is used for treatment planning in RGRT. We have previously developed a respiratory guiding system that incorporates an individual-specific guiding waveform, which is easy to follow for each volunteer, to improve the respiratory regularity. The present study evaluates the application of this system to improve the respiratory regularity for respiratory-gated radiation therapy (RGRT). In this study, we evaluated the effectiveness of an in-house-developed respiratory guiding system incorporating an individual specific guiding waveform to improve the respiratory regularity for RGRT. Most volunteers showed significantly less residual motion at each phase during guided breathing owing to the improvement in respiratory regularity. Therefore, the respiratory guiding system can clearly reduce the residual, or respiratory, motion in each phase. From the result, the CTV and the PTV margins during RGRT can be reduced by using the respiratory guiding system, which reduces the residual motions, thus improving the accuracy of RGRT

The Distribution, Diversity, and Geobiology of Thermoproteales Populations in Yellowstone National Park

Science.gov (United States)

Jay, Z.; Beam, J.; Bailey, C.; Dohnalkova, A.; Planer-Friedrich, B.; Romine, M.; Inskeep, W. P.

2012-12-01

, arsenate, or tetrathionate. One of the relevant Thermoproteales Type-II populations was isolated from JCHS and is an anaerobic heterotroph utilizing yeast extract as a carbon and energy source while respiring on elemental sulfur or arsenate, resulting in the production of sulfide or arsenite, respectively. The optimum growth temperature of strain WP30 (75° C) and pH range (4.5 - 7) corresponds well with characteristics of the sulfidic sediment used as the original inoculum. A draft genome of strain WP30 reveals that respiration may involve as many as four dimethylsulfoxide molybdopterin oxidoreductases including a putative sulfur reductase and an arsenate reductase. Sequences with high amino acid identity to these reductases were also identified in metagenome data sets from sites containin Type-II populations. Expression data of these terminal reductase genes during the growth of strain WP30 on either sulfur or arsenate were compared to expression results from field sites. These data provide insights regarding the diversity, distribution, and potential role of Thermoproteales-like populations in high-temperature environments of YNP.

Soil and sediment concentrations of chromium, copper, and arsenic adjacent to a chromated copper arsenate-treated wetland boardwalk

Science.gov (United States)

Stan Lebow; Daniel Foster

2010-01-01

Environmental accumulation of preservative adjacent to a chromated copper arsenate (type C)–treated wetland boardwalk was evaluated. The site is considered a realistic ‘‘worst case’’ because of the large volume of treated wood, low current speeds, high annual rainfall, and environmental sensitivity. Soil and sediment samples were collected before construction and 0.5,...

Gene cloning and overexpression of two conjugated polyketone reductases, novel aldo-keto reductase family enzymes, of Candida parapsilosis.

Science.gov (United States)

Kataoka, M; Delacruz-Hidalgo, A-R G; Akond, M A; Sakuradani, E; Kita, K; Shimizu, S

2004-04-01

The genes encoding two conjugated polyketone reductases (CPR-C1, CPR-C2) of Candida parapsilosis IFO 0708 were cloned and sequenced. The genes encoded a total of 304 and 307 amino acid residues for CPR-C1 and CPR-C2, respectively. The deduced amino acid sequences of the two enzymes showed high similarity to each other and to several proteins of the aldo-keto reductase (AKR) superfamily. However, several amino acid residues in putative active sites of AKRs were not conserved in CPR-C1 and CPR-C2. The two CPR genes were overexpressed in Escherichia coli. The E. coli transformant bearing the CPR-C2 gene almost stoichiometrically reduced 30 mg ketopantoyl lactone/ml to D-pantoyl lactone.

Identification of 5α-reductase isoenzymes in canine skin.

Science.gov (United States)

Bernardi de Souza, Lucilene; Paradis, Manon; Zamberlam, Gustavo; Benoit-Biancamano, Marie-Odile; Price, Christopher

2015-10-01

Alopecia X in dogs is a noninflammatory alopecia that may be caused by a hormonal dysfunction. It may be similar to androgenic alopecia in men that is caused by the effect of dihydrotestosterone (DHT). The 5α-reductase isoenzymes, 5αR1 and 5αR2, and a recently described 5αR3, are responsible for the conversion of testosterone into DHT. However, which 5α-reductases are present in canine skin has not yet been described. The main objective of this study was to determine the pattern of expression of 5α-reductase genes in canine skin. Skin biopsies were obtained from healthy, intact young-mature beagles (three males, four females) at three anatomical sites normally affected by alopecia X (dorsal neck, back of thighs and base of tail) and two sites generally unaffected (dorsal head and ventral thorax). Prostate samples (n = 3) were collected as positive controls for 5α-reductase mRNA abundance measurement by real-time PCR. We detected mRNA encoding 5αR1 and 5αR3 but not 5αR2. There were no significant differences in 5αR1 and 5αR3 mRNA levels between the different anatomical sites, irrespective of gender (P > 0.05). Moreover, the mean mRNA abundance in each anatomical site did not differ between males and females (P > 0.05). To the best of the authors' knowledge, this is the first study demonstrating the expression of 5α-reductases in canine skin and the expression of 5αR3 in this tissue. These results may help to elucidate the pathogenesis of alopecia X and to determine more appropriate treatments for this disorder. © 2015 ESVD and ACVD.

Gamma-irradiation activates biochemical systems: induction of nitrate reductase activity in plant callus.

OpenAIRE

Pandey, K N; Sabharwal, P S

1982-01-01

Gamma-irradiation induced high levels of nitrate reductase activity (NADH:nitrate oxidoreductase, EC 1.6.6.1) in callus of Haworthia mirabilis Haworth. Subcultures of gamma-irradiated tissues showed autonomous growth on minimal medium. We were able to mimic the effects of gamma-irradiation by inducing nitrate reductase activity in unirradiated callus with exogenous auxin and kinetin. These results revealed that induction of nitrate reductase activity by gamma-irradiation is mediated through i...

Bacteria, hypertolerant to arsenic in the rocks of an ancient gold mine, and their potential role in dissemination of arsenic pollution

International Nuclear Information System (INIS)

Drewniak, Lukasz; Styczek, Aleksandra; Majder-Lopatka, Malgorzata; Sklodowska, Aleksandra

2008-01-01

The aim of the present study was to find out if bacteria present in ancient gold mine could transform immobilized arsenic into its mobile form and increase its dissemination in the environment. Twenty-two arsenic-hypertolerant cultivable bacterial strains were isolated. No chemolithoautotrophs, which could use arsenite as an electron donor as well as arsenate as an electron acceptor, were identified. Five isolates exhibited hypertolerance to arsenic: up to 500 mM of arsenate. A correlation between the presence of siderophores and high resistance to arsenic was found. The results of this study show that detoxification processes based on arsenate reductase activity might be significant in dissemination of arsenic pollution. It was concluded that the activity of the described heterotrophic bacteria contributes to the mobilization of arsenic in the more toxic As(III) form and a new mechanism of arsenic mobilization from a scorodite was proposed. - The activity of the described heterotrophic bacteria leads to mobilization of arsenic and in this way contributes to the dissemination of arsenic pollution

Urinary arsenic speciation profiles in mice subchronically exposed to low concentrations of sodium arsenate in drinking water

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Huijie Wu

2011-09-01

Full Text Available Arsenic is a proven human carcinogen. Although the mechanism of its carcinogenicity is still largely unknown, methylation is thought to have an important role to play in arsenic toxicity. In this study, urinary methylation profiles were investigated in female C57BL/6J black mice given drinking water containing 500 μg arsenate (AsV/L, 250 μg AsV/L, or 100 μg AsV/L as sodium arsenate for 2 months. The concentrations of arsenic chosen reflected those in the drinking water often encountered in arsenic-endemic areas. Urine samples were collected from the mice at the end of the exposure period, and the arsenic species were analyzed by high performance liquid chromatography-inductively coupled plasma-mass spectrometry. All detectable arsenic species showed strong linear correlation with the administered dosage. The methylation patterns were similar in all three groups with a slight decrease of dimethylarsinic acid/AsV ratio in the 500-μg/L group, which corresponded to the significantly higher arsenic retention in the tissue. The results indicate that urinary arsenic could be used as a good biomarker for internal dose and potential biological effects. Different doses of arsenic exposure could result in different degrees of methylation, excretion, and tissue retention, and this may contribute to the understanding of arsenic carcinogenicity.

Transcripts of Anthocyanidin Reductase and Leucoanthocyanidin Reductase and Measurement of Catechin and Epicatechin in Tartary Buckwheat

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Yeon Bok Kim

2014-01-01

Full Text Available Anthocyanidin reductase (ANR and leucoanthocyanidin reductase (LAR play an important role in the monomeric units biosynthesis of proanthocyanidins (PAs such as catechin and epicatechin in several plants. The aim of this study was to clone ANR and LAR genes involved in PAs biosynthesis and examine the expression of these two genes in different organs under different growth conditions in two tartary buckwheat cultivars, Hokkai T8 and T10. Gene expression was carried out by quantitative real-time RT-PCR, and catechin and epicatechin content was analyzed by high performance liquid chromatography. The expression pattern of ANR and LAR did not match the accumulation pattern of PAs in different organs of two cultivars. Epicatechin content was the highest in the flowers of both cultivars and it was affected by light in only Hokkai T8 sprouts. ANR and LAR levels in tartary buckwheat might be regulated by different mechanisms for catechin and epicatechin biosynthesis under light and dark conditions.

Comparative modelling and molecular docking of nitrate reductase from Bacillus weihenstephanensis (DS45

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R. Seenivasagan

2016-07-01

Full Text Available Nitrate reductase catalyses the oxidation of NAD(PH and the reduction of nitrate to nitrite. NR serves as a central point for the integration of metabolic pathways by governing the flux of reduced nitrogen through several regulatory mechanisms in plants, algae and fungi. Bacteria express nitrate reductases that convert nitrate to nitrite, but mammals lack these specific enzymes. The microbial nitrate reductase reduces toxic compounds to nontoxic compounds with the help of NAD(PH. In the present study, our results revealed that Bacillus weihenstephanensis expresses a nitrate reductase enzyme, which was made to generate the 3D structure of the enzyme. Six different modelling servers, namely Phyre2, RaptorX, M4T Server, HHpred, SWISS MODEL and Mod Web, were used for comparative modelling of the structure. The model was validated with standard parameters (PROCHECK and Verify 3D. This study will be useful in the functional characterization of the nitrate reductase enzyme and its docking with nitrate molecules, as well as for use with autodocking.

Rice-arsenate interactions in hydroponics: a three-gene model for tolerance.

Science.gov (United States)

Norton, Gareth J; Nigar, Meher; Williams, Paul N; Dasgupta, Tapash; Meharg, Andrew A; Price, Adam H

2008-01-01

In this study, the genetic mapping of the tolerance of root growth to 13.3 muM arsenate [As(V)] using the BalaxAzucena population is improved, and candidate genes for further study are identified. A remarkable three-gene model of tolerance is advanced, which appears to involve epistatic interaction between three major genes, two on chromosome 6 and one on chromosome 10. Any combination of two of these genes inherited from the tolerant parent leads to the plant having tolerance. Lists of potential positional candidate genes are presented. These are then refined using whole genome transcriptomics data and bioinformatics. Physiological evidence is also provided that genes related to phosphate transport are unlikely to be behind the genetic loci conferring tolerance. These results offer testable hypotheses for genes related to As(V) tolerance that might offer strategies for mitigating arsenic (As) accumulation in consumed rice.

Rice–arsenate interactions in hydroponics: a three-gene model for tolerance

Science.gov (United States)

Norton, Gareth J.; Nigar, Meher; Dasgupta, Tapash; Meharg, Andrew A.; Price, Adam H.

2008-01-01

In this study, the genetic mapping of the tolerance of root growth to 13.3 μM arsenate [As(V)] using the Bala×Azucena population is improved, and candidate genes for further study are identified. A remarkable three-gene model of tolerance is advanced, which appears to involve epistatic interaction between three major genes, two on chromosome 6 and one on chromosome 10. Any combination of two of these genes inherited from the tolerant parent leads to the plant having tolerance. Lists of potential positional candidate genes are presented. These are then refined using whole genome transcriptomics data and bioinformatics. Physiological evidence is also provided that genes related to phosphate transport are unlikely to be behind the genetic loci conferring tolerance. These results offer testable hypotheses for genes related to As(V) tolerance that might offer strategies for mitigating arsenic (As) accumulation in consumed rice. PMID:18453529

Glutathione reductase: solvent equilibrium and kinetic isotope effects

International Nuclear Information System (INIS)

Wong, K.K.; Vanoni, M.A.; Blanchard, J.S.

1988-01-01

Glutathione reductase catalyzes the NADPH-dependent reduction of oxidized glutathione (GSSG). The kinetic mechanism is ping-pong, and we have investigated the rate-limiting nature of proton-transfer steps in the reactions catalyzed by the spinach, yeast, and human erythrocyte glutathione reductases using a combination of alternate substrate and solvent kinetic isotope effects. With NADPH or GSSG as the variable substrate, at a fixed, saturating concentration of the other substrate, solvent kinetic isotope effects were observed on V but not V/K. Plots of Vm vs mole fraction of D 2 O (proton inventories) were linear in both cases for the yeast, spinach, and human erythrocyte enzymes. When solvent kinetic isotope effect studies were performed with DTNB instead of GSSG as an alternate substrate, a solvent kinetic isotope effect of 1.0 was observed. Solvent kinetic isotope effect measurements were also performed on the asymmetric disulfides GSSNB and GSSNP by using human erythrocyte glutathione reductase. The Km values for GSSNB and GSSNP were 70 microM and 13 microM, respectively, and V values were 62 and 57% of the one calculated for GSSG, respectively. Both of these substrates yield solvent kinetic isotope effects greater than 1.0 on both V and V/K and linear proton inventories, indicating that a single proton-transfer step is still rate limiting. These data are discussed in relationship to the chemical mechanism of GSSG reduction and the identity of the proton-transfer step whose rate is sensitive to solvent isotopic composition. Finally, the solvent equilibrium isotope effect measured with yeast glutathione reductase is 4.98, which allows us to calculate a fractionation factor for the thiol moiety of GSH of 0.456

Substrate and cofactor binding to nitrile reductase : A mass spectrometry based study

NARCIS (Netherlands)

Gjonaj, L.; Pinkse, M.W.H.; Fernandez Fueyo, E.; Hollmann, F.; Hanefeld, U.

2016-01-01

Nitrile reductases catalyse a two-step reduction of nitriles to amines. This requires the binding of two NADPH molecules during one catalytic cycle. For the nitrile reductase from E. coli (EcoNR) mass spectrometry studies of the catalytic mechanism were performed. EcoNR is dimeric and has no Rossman

Influence of dietary selenium on the disposition of arsenate in the female B6C3F{sub 1} mouse

Energy Technology Data Exchange (ETDEWEB)

Kenyon, E.M.; Hughes, M.F. [Environmental Protection Agency, Research Triangle Park, NC (United States); Levander, O.A. [Nutrient Requirements and Functions Lab., Beltsville, MD (United States)

1997-06-27

Interactions between arsenic (As) and selenium (Se) at the metabolic level are multifaceted and complex. These interactions are of practical significance because populations in various parts of the world are simultaneously exposed to inorganic As in drinking water and Se mainly in the diet at varying levels. The primary goal of this study was to investigate whether differing dietary Se status would alter the profile of urinary metabolites or their time course for elimination after exposure to arsenate [As(V)]. Weanling female 86C3F, mice were maintained for 28 d on either a control diet of powdered rodent meal sufficient in Se (A 0.2 ppm) or Torula yeast-based (TYB) diets deficient (B, 0.02 ppm Se), sufficient (C, 0.2 ppm Se), or excessive (D, 2.0 ppm Se) in Se; mice then received by oral gavage 5 mg (As)/kg as sodium [{sup 73}As] arsenate. The time course for elimination of total arsenic and metabolites in urine was measured over a 48-h period, and total arsenic was determined in feces and tissues at 48 h. Mice on the Se excess diet excreted a significantly higher percentage of urinary As as inorganic As, with a significantly decreased ratio of organic to inorganic As compared to Se-sufficient mice, suggesting that As methylation was decreased. Mice on the Se-deficient diet appeared to eliminate As(V), arsenite, and dimethylarsinic acid (DMA) in urine more slowly than Se-sufficient mice; however, further studies are required to confirm this finding. Mice on the Se-sufficient meal diet (A) excreted significantly less (by percent) arsenate-derived radioactivity in urine and more in feces compared to mice on the Se-sufficient TYB diet (C), with total elimination being similar for both groups. This indicates that mice on the meal diet absorbed significantly less As(V) than mice on the TYB diet, and this may be due to more fiber or {open_quotes}bulk{close_quotes} in the meal diet. 35 refs., 6 figs., 6 tabs.

N-terminus determines activity and specificity of styrene monooxygenase reductases.

Science.gov (United States)

Heine, Thomas; Scholtissek, Anika; Westphal, Adrie H; van Berkel, Willem J H; Tischler, Dirk

2017-12-01

Styrene monooxygenases (SMOs) are two-enzyme systems that catalyze the enantioselective epoxidation of styrene to (S)-styrene oxide. The FADH 2 co-substrate of the epoxidase component (StyA) is supplied by an NADH-dependent flavin reductase (StyB). The genome of Rhodococcus opacus 1CP encodes two SMO systems. One system, which we define as E1-type, displays homology to the SMO from Pseudomonas taiwanensis VLB120. The other system, originally reported as a fused system (RoStyA2B), is defined as E2-type. Here we found that E1-type RoStyB is inhibited by FMN, while RoStyA2B is known to be active with FMN. To rationalize the observed specificity of RoStyB for FAD, we generated an artificial reductase, designated as RoStyBart, in which the first 22 amino acid residues of RoStyB were joined to the reductase part of RoStyA2B, while the oxygenase part (A2) was removed. RoStyBart mainly purified as apo-protein and mimicked RoStyB in being inhibited by FMN. Pre-incubation with FAD yielded a turnover number at 30°C of 133.9±3.5s -1 , one of the highest rates observed for StyB reductases. RoStyBart holo-enzyme switches to a ping-pong mechanism and fluorescence analysis indicated for unproductive binding of FMN to the second (co-substrate) binding site. In summary, it is shown for the first time that optimization of the N-termini of StyB reductases allows the evolution of their activity and specificity. Copyright © 2017 Elsevier B.V. All rights reserved.

Prevalence of methylenetetrahydrofolate reductase ( MTHFR ) and ...

African Journals Online (AJOL)

Methylenetetrahydrofolate reductase (MTHFR) and Cytosolic serine hydroxymethyltransferase (cSHMT) are enzymes involve in folate regulation in human. The C to T transition of the cSHMT and MTHFR genes at the 1420 as well as 677 nucleotides both carries TT genotype respectively. These enzymes have direct and ...

Methemoglobin reductase activity in intact fish red blood cells

DEFF Research Database (Denmark)

Jensen, Frank B; Nielsen, Karsten

2018-01-01

RBCs in physiological saline at normal Pco2 and pH. After initial loading of oxygenated RBCs with nitrite (partly oxidizing Hb to metHb), the nitrite is removed by three washes of the RBCs in nitrite-free physiological saline to enable the detection of RBC metHb reductase activity in the absence......Hb reductase activity in fish offsets their higher Hb autoxidation and higher likelihood of encountering elevated nitrite. Deoxygenation significantly raised the rates of RBC metHb reduction, and more so in rainbow trout than in carp. The temperature sensitivity of metHb reduction in rainbow trout RBCs...

Molecular mechanisms of drug resistance and tumor promotion involving mammalian ribonucleotide reductase

Energy Technology Data Exchange (ETDEWEB)

Choy, B.B.K.

1991-01-01

Mammalian ribonucleotide reductase is a highly regulated, rate-limiting activity responsible for converting ribonucleoside diphosphates to the deoxyribonucleotide precursors of DNA. The enzyme consists of two nonidentical proteins called M1 and M2, both of which are required for activity. Hydroxyurea is an antitumor agent which inhibits ribonucleotide reductase by interacting with the M2 component specifically at a unique tyrosyl free radical. Studies were conducted on a series of drug resistant mouse cell lines, selected by a step-wise procedure for increasing levels of resistance to the cytotoxic effects of hydroxyurea. Each successive drug selection step leading to the isolation of highly resistant cells was accompanied by stable elevations in cellular resistance and ribonucleotide reductase activity. The drug resistant cell lines exhibited gene amplification of the M2 gene, elevated M2 mRNA, and M2 protein. In addition to M2 gene amplification, posttranscriptional modulation also occurred during the drug selection. Studies of the biosynthesis rates with exogenously added iron suggest a role for iron in regulating the level of M2 protein when cells are cultured in the presence of hydroxyurea. The hydroxyurea-inactivated ribonucleotide reductase protein M2 has a destabilized iron centre, which readily releases iron. Altered expression of ferritin appears to be required for the development of hydroxyurea resistance in nammalian cells. The results show an interesting relationship between the expressions of ribonucleotide reductase and ferritin. The phorbol ester tumor promoter, TPA, is also able to alter the expression of M2. TPA was able to induce M2 mRNA levels transiently up to 18-fold within 1/2 hour. This rapid and large elevation of ribonucleotide reductase suggests that the enzyme may play a role in tumor promotion. Studies of the M2 promoter region were undertaken to better understand the mechanism of TPA induction of M2.

BIOLOGICAL ROLE OF ALDO-KETO REDUCTASES IN RETINOIC ACID BIOSYNTHESIS AND SIGNALING

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F. Xavier eRuiz

2012-04-01

Full Text Available Several aldo-keto reductase (AKR enzymes from subfamilies 1B and 1C show retinaldehyde reductase activity, having low Km and kcat values. Only AKR1B10 and 1B12, with all-trans-retinaldehyde, and AKR1C3, with 9-cis-retinaldehyde, display high catalytic efficiency. Major structural determinants for retinaldehyde isomer specificity are located in the external loops (A and C for AKR1B10, and B for AKR1C3, as assessed by site-directed mutagenesis and molecular dynamics. Cellular models have shown that AKR1B and 1C enzymes are well suited to work in vivo as retinaldehyde reductases and to regulate retinoic acid (RA biosynthesis at hormone pre-receptor level. An additional physiological role for the retinaldehyde reductase activity of these enzymes, consistent with their tissue localization, is their participation in β-carotene absorption. Retinaldehyde metabolism may be subjected to subcellular compartmentalization, based on enzyme localization. While retinaldehyde oxidation to RA takes place in the cytosol, reduction to retinol could take place in the cytosol by AKRs or in the membranes of endoplasmic reticulum by microsomal retinaldehyde reductases. Upregulation of some AKR1 enzymes in different cancer types may be linked to their induction by oxidative stress and to their participation in different signaling pathways related to cell proliferation. AKR1B10 and AKR1C3, through their retinaldehyde reductase activity, trigger a decrease in the RA biosynthesis flow, resulting in RA deprivation and consequently lower differentiation, with an increased cancer risk in target tissues. Rational design of selective AKR inhibitors could lead to development of novel drugs for cancer treatment as well as reduction of chemotherapeutic drug resistance.

Identification of Multiple Soluble Fe(III Reductases in Gram-Positive Thermophilic Bacterium Thermoanaerobacter indiensis BSB-33

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Subrata Pal

2014-01-01

Full Text Available Thermoanaerobacter indiensis BSB-33 has been earlier shown to reduce Fe(III and Cr(VI anaerobically at 60°C optimally. Further, the Gram-positive thermophilic bacterium contains Cr(VI reduction activity in both the membrane and cytoplasm. The soluble fraction prepared from T. indiensis cells grown at 60°C was found to contain the majority of Fe(III reduction activity of the microorganism and produced four distinct bands in nondenaturing Fe(III reductase activity gel. Proteins from each of these bands were partially purified by chromatography and identified by mass spectrometry (MS with the help of T. indiensis proteome sequences. Two paralogous dihydrolipoamide dehydrogenases (LPDs, thioredoxin reductase (Trx, NADP(H-nitrite reductase (Ntr, and thioredoxin disulfide reductase (Tdr were determined to be responsible for Fe(III reductase activity. Amino acid sequence and three-dimensional (3D structural similarity analyses of the T. indiensis Fe(III reductases were carried out with Cr(VI reducing proteins from other bacteria. The two LPDs and Tdr showed very significant sequence and structural identity, respectively, with Cr(VI reducing dihydrolipoamide dehydrogenase from Thermus scotoductus and thioredoxin disulfide reductase from Desulfovibrio desulfuricans. It appears that in addition to their iron reducing activity T. indiensis LPDs and Tdr are possibly involved in Cr(VI reduction as well.

Thioredoxin reductase deficiency potentiates oxidative stress, mitochondrial dysfunction and cell death in dopaminergic cells.

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Pamela Lopert

Full Text Available Mitochondria are considered major generators of cellular reactive oxygen species (ROS which are implicated in the pathogenesis of neurodegenerative diseases such as Parkinson's disease (PD. We have recently shown that isolated mitochondria consume hydrogen peroxide (H₂O₂ in a substrate- and respiration-dependent manner predominantly via the thioredoxin/peroxiredoxin (Trx/Prx system. The goal of this study was to determine the role of Trx/Prx system in dopaminergic cell death. We asked if pharmacological and lentiviral inhibition of the Trx/Prx system sensitized dopaminergic cells to mitochondrial dysfunction, increased steady-state H₂O₂ levels and death in response to toxicants implicated in PD. Incubation of N27 dopaminergic cells or primary rat mesencephalic cultures with the Trx reductase (TrxR inhibitor auranofin in the presence of sub-toxic concentrations of parkinsonian toxicants paraquat; PQ or 6-hydroxydopamine; 6OHDA (for N27 cells resulted in a synergistic increase in H₂O₂ levels and subsequent cell death. shRNA targeting the mitochondrial thioredoxin reductase (TrxR2 in N27 cells confirmed the effects of pharmacological inhibition. A synergistic decrease in maximal and reserve respiratory capacity was observed in auranofin treated cells and TrxR2 deficient cells following incubation with PQ or 6OHDA. Additionally, TrxR2 deficient cells showed decreased basal mitochondrial oxygen consumption rates. These data demonstrate that inhibition of the mitochondrial Trx/Prx system sensitizes dopaminergic cells to mitochondrial dysfunction, increased steady-state H₂O₂, and cell death. Therefore, in addition to their role in the production of cellular H₂O₂ the mitochondrial Trx/Prx system serve as a major sink for cellular H₂O₂ and its disruption may contribute to dopaminergic pathology associated with PD.

In silico docking studies of aldose reductase inhibitory activity of commercially available flavonoids

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Arumugam Madeswaran

2012-12-01

Full Text Available The primary objective of this study was to investigate the aldose reductase inhibitory activity of flavonoids using in silico docking studies. In this perspective, flavonoids like biochanin, butein, esculatin, fisetin and herbacetin were selected. Epalrestat, a known aldose reductase inhibitor was used as the standard. In silico docking studies were carried out using AutoDock 4.2, based on the Lamarckian genetic algorithm principle. The results showed that all the selected flavonoids showed binding energy ranging between -9.33 kcal/mol to -7.23 kcal/mol when compared with that of the standard (-8.73 kcal/mol. Inhibition constant (144.13 µM to 4.98 µM and intermolecular energy (-11.42 kcal/mol to -7.83 kcal/mol of the flavonoids also coincide with the binding energy. All the selected flavonoids contributed aldose reductase inhibitory activity because of its structural properties. These molecular docking analyses could lead to the further development of potent aldose reductase inhibitors for the treatment of diabetes.

Crystallization and preliminary X-ray diffraction analysis of maize aldose reductase

Energy Technology Data Exchange (ETDEWEB)

Kiyota, Eduardo [Laboratório de Biologia Estrutural, Instituto de Química, Universidade Estadual de Campinas, CP 6154, 13083-970 Campinas-SP (Brazil); Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas-SP (Brazil); Sousa, Sylvia Morais de [Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas-SP (Brazil); Santos, Marcelo Leite dos; Costa Lima, Aline da [Laboratório de Biologia Estrutural, Instituto de Química, Universidade Estadual de Campinas, CP 6154, 13083-970 Campinas-SP (Brazil); Menossi, Marcelo [Departamento de Genética e Evolução, Instituto de Biologia, Universidade Estadual de Campinas, Campinas-SP (Brazil); Yunes, José Andrés [Laboratório de Biologia Molecular, Centro Infantil Boldrini, Campinas-SP (Brazil); Aparicio, Ricardo, E-mail: aparicio@iqm.unicamp.br [Laboratório de Biologia Estrutural, Instituto de Química, Universidade Estadual de Campinas, CP 6154, 13083-970 Campinas-SP (Brazil)

2007-11-01

Preliminary X-ray diffraction studies of apo maize aldose reductase at 2.0 Å resolution are reported. Maize aldose reductase (AR) is a member of the aldo-keto reductase superfamily. In contrast to human AR, maize AR seems to prefer the conversion of sorbitol into glucose. The apoenzyme was crystallized in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 47.2, b = 54.5, c = 100.6 Å and one molecule in the asymmetric unit. Synchrotron X-ray diffraction data were collected and a final resolution limit of 2.0 Å was obtained after data reduction. Phasing was carried out by an automated molecular-replacement procedure and structural refinement is currently in progress. The refined structure is expected to shed light on the functional/enzymatic mechanism and the unusual activities of maize AR.

Crystallization and preliminary X-ray diffraction analysis of maize aldose reductase

International Nuclear Information System (INIS)

Kiyota, Eduardo; Sousa, Sylvia Morais de; Santos, Marcelo Leite dos; Costa Lima, Aline da; Menossi, Marcelo; Yunes, José Andrés; Aparicio, Ricardo

2007-01-01

Preliminary X-ray diffraction studies of apo maize aldose reductase at 2.0 Å resolution are reported. Maize aldose reductase (AR) is a member of the aldo-keto reductase superfamily. In contrast to human AR, maize AR seems to prefer the conversion of sorbitol into glucose. The apoenzyme was crystallized in space group P2 1 2 1 2 1 , with unit-cell parameters a = 47.2, b = 54.5, c = 100.6 Å and one molecule in the asymmetric unit. Synchrotron X-ray diffraction data were collected and a final resolution limit of 2.0 Å was obtained after data reduction. Phasing was carried out by an automated molecular-replacement procedure and structural refinement is currently in progress. The refined structure is expected to shed light on the functional/enzymatic mechanism and the unusual activities of maize AR

Regulation and function of versatile aerobic and anaerobic respiratory metabolism in Pseudomonas aeruginosa

Directory of Open Access Journals (Sweden)

Hiroyuki eArai

2011-05-01

Full Text Available Pseudomonas aeruginosa is a ubiquitously distributed opportunistic pathogen that inhabits soil and water as well as animal-, human-, and plant-host-associated environments. The ubiquity would be attributed to its very versatile energy metabolism. P. aeruginosa has a highly branched respiratory chain terminated by multiple terminal oxidases and denitrification enzymes. Five terminal oxidases for aerobic respiration have been identified in the P. aeruginosa cells. Three of them, the cbb3-1 oxidase, the cbb3-2 oxidase, and the aa3 oxidase, are cytochrome c oxidases and the other two, the bo3 oxidase and the cyanide-insensitive oxidase, are quinol oxidases. Each oxidase has a specific affinity for oxygen, efficiency of energy coupling, and tolerance to various stresses such as cyanide and reactive nitrogen species. These terminal oxidases are used differentially according to the environmental conditions. P. aeruginosa also has a complete set of the denitrification enzymes that reduce nitrate to molecular nitrogen via nitrite, nitric oxide (NO, and nitrous oxide. These nitrogen oxides function as alternative electron acceptors and enable P. aeruginosa to grow under anaerobic conditions. One of the denitrification enzymes, NO reductase, is also expected to function for detoxification of NO produced by the host immune defense system. The control of the expression of these aerobic and anaerobic respiratory enzymes would contribute to the adaptation of P. aeruginosa to a wide range of environmental conditions including in the infected hosts. Characteristics of these respiratory enzymes and the regulatory system that controls the expression of the respiratory genes in the P. aeruginosa cells are overviewed in this article.

Purification of nitrate reductase from Nicotiana plumbaginifolia by affinity chromatography using 5'AMP-sepharose and monoclonal antibodies.

Science.gov (United States)

Moureaux, T; Leydecker, M T; Meyer, C

1989-02-15

Nitrate reductase was purified from leaves of Nicotiana plumbaginifolia using either 5'AMP-Sepharose chromatography or two steps of immunoaffinity chromatography involving monoclonal antibodies directed against nitrate reductase from maize and against ribulose-1,5-bisphosphate carboxylase from N. plumbaginifolia. Nitrate reductase obtained by the first method was purified 1000-fold to a specific activity of 9 units/mg protein. The second method produced an homogenous enzyme, purified 21,000-fold to a specific activity of 80 units/mg protein. SDS/PAGE of nitrate reductase always resulted in two bands of 107 and 99.5 kDa. The 107-kDa band was the nitrate reductase subunit of N. plumbaginifolia; the smaller one of 99.5 kDa is thought, as commonly reported, to result from proteolysis of the larger protein. The molecular mass of 107 kDa is close to the values calculated from the coding sequences of the two nitrate reductase genes recently cloned from tobacco (Nicotiana tabacum cv Xanthi).

Constitutive non-inducible expression of the Arabidopsis thaliana Nia 2 gene in two nitrate reductase mutants of Nicotiana plumbaginifolia.

Science.gov (United States)

Kaye, C; Crawford, N M; Malmberg, R L

1997-04-01

We have isolated a haploid cell line of N. plumbaginifolia, hNP 588, that is constitutive and not inducible for nitrate reductase. Nitrate reductase mutants were isolated from hNP 588 protoplasts upon UV irradiation. Two of these nitrate reductase-deficient cell lines, nia 3 and nia 25, neither of which contained any detectable nitrate reductase activity, were selected for complementation studies. A cloned Arabidopsis thaliana nitrate reductase gene Nia 2 was introduced into each of the two mutants resulting in 56 independent kanamycin-resistant cell lines. Thirty of the 56 kanamycin-resistant cell lines were able to grow on nitrate as the sole nitrogen source. Eight of these were further analyzed for nitrate reductase enzyme activity and nitrate reductase mRNA production. All eight lines had detectable nitrate reductase activity ranging from 7% to 150% of wild-type hNP 588 callus. The enzyme activity levels were not influenced by the nitrogen source in the medium. The eight lines examined expressed a constitutive, non-inducible 3.2 kb mRNA species that was not present in untransformed controls.

Estimation of enthalpies and entropies of melting of arsenates from phase diagrams of MeAsO3-Me3AsO4 (Me=Na,K,Rb,Cs) and correlation of thermodynamic properties of alkali metal arsenates

International Nuclear Information System (INIS)

Kasenov, B.K.; Isabaev, S.M.; Buketov, E.A.

1982-01-01

Values of ΔHsub(melting)sup(0) and ΔSsub(melting)sup(0) for Na 3 AsO 4 , K 3 AsO 4 , Rb 3 AsO 4 and Cs 3 AsO 4 (65.3 kJ/mol and 44.4 J/molxK respectively) were calculated by the Shredder-Vant-Hoff equation in the approximation of ideal solutions from diagrams of the state of MeAsO 3 -He 3 AsO 4 (Me=Na, K, Rb, Cs) systems. ΔHsub(298)sup(0)-f(Tsub(melting)) and ΔHsub(melting)sup(0)-f(ΔHsub(298)sup(0)) dependences were found for arsenates

Overexpression of chloroplast NADPH-dependent thioredoxin reductase in Arabidopsis enhances leaf growth and elucidates in-vivo function of reductase and thioredoxin domains

Directory of Open Access Journals (Sweden)

Jouni eToivola

2013-10-01

Full Text Available Plant chloroplasts have versatile thioredoxin systems including two thioredoxin reductases and multiple types of thioredoxins. Plastid-localized NADPH-dependent thioredoxin reductase (NTRC contains both reductase (NTRd and thioredoxin (TRXd domains in a single polypeptide and forms homodimers. To study the action of NTRC and NTRC domains in vivo, we have complemented the ntrc knockout line of Arabidopsis with the wild type and full-length NTRC genes, in which 2-Cys motifs either in NTRd, or in TRXd were inactivated. The ntrc line was also transformed either with the truncated NTRd or TRXd alone. Overexpression of wild-type NTRC promoted plant growth by increasing leaf size and biomass yield of the rosettes. Complementation of the ntrc line with the full-length NTRC gene containing an active reductase but an inactive thioredoxin domain, or vice versa, recovered wild-type chloroplast phenotype and, partly, rosette biomass production, indicating that the NTRC domains are capable of interacting with other chloroplast thioredoxin systems. Overexpression of truncated NTRd or TRXd in ntrc background did not restore wild-type phenotype. Modelling of the 3-dimensional structure of the NTRC dimer indicates extensive interactions between the NTR domains and the TRX domains further stabilize the dimeric structure. The long linker region between the NTRd and TRXd, however, allows flexibility for the position of the TRXd in the dimer. Supplementation of the TRXd in the NTRC homodimer model by free chloroplast thioredoxins indicated that TRXf is the most likely partner to interact with NTRC. We propose that overexpression of NTRC promotes plant biomass yield both directly by stimulation of chloroplast biosynthetic and protected pathways controlled by NTRC and indirectly via free chloroplast thioredoxins. Our data indicate that overexpression of chloroplast thiol redox-regulator has a potential to increase biofuel yield in plant and algal species suitable for

Nizatidine and omeprazole enhance the effect of metronidazole on Helicobacter pylori in vitro

DEFF Research Database (Denmark)

Chen, Ming; Jensen, Bente; Zhai, Lin

2002-01-01

to reverse antibiotic resistance do not necessarily have an antibiotic or chemotherapeutic effect in the sense of growth inhibition. Therefore, it was decided to investigate the effect of nizatidine and omeprazole on the oxidative respiratory chain, as it is known that metronidazole is able to inhibit...... the activity of fumarate reductase of H. pylori. This enzyme is a key enzyme in the alternative respiratory chain under anaerobic conditions. Nizatidine was, in these preliminary experiments, found to inhibit fumarate reductase in a dose-dependent way, like metronidazole, whereas omeprazole had almost...... no effect on fumarate reductase. No other significant effects on the enzymes of the respiratory chain were found. The synergistic effect of nizatidine on metronidazole resistant H. pylori strains could be explained by the effect on fumarate reductase, whereas the effect of omeprazole is different and could...

The structure of Lactococcus lactis thioredoxin reductase reveals molecular features of photo-oxidative damage

DEFF Research Database (Denmark)

Skjoldager, Nicklas; Bang, Maria Blanner; Rykær, Martin

2017-01-01

The NADPH-dependent homodimeric flavoenzyme thioredoxin reductase (TrxR) provides reducing equivalents to thioredoxin, a key regulator of various cellular redox processes. Crystal structures of photo-inactivated thioredoxin reductase (TrxR) from the Gram-positive bacterium Lactococcus lactis have...

Characterization and regulation of Leishmania major 3-hydroxy-3-methylglutaryl-CoA reductase

DEFF Research Database (Denmark)

Montalvetti, A; Pena Diaz, Javier; Hurtado, R

2000-01-01

In eukaryotes the enzyme 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase catalyses the synthesis of mevalonic acid, a common precursor to all isoprenoid compounds. Here we report the isolation and overexpression of the gene coding for HMG-CoA reductase from Leishmania major. The protein from L...

Methylenetetrahydrofolate reductase gene polymorphism in type 1 ...

African Journals Online (AJOL)

In patients with type-I diabetes mellitus folate deficiency is associated with endothelial dysfunction. So, polymorphism in genes involved in folate metabolism may have a role in vascular disease. This study was designed to evaluate the relationship between methylenetetrahydrofolate reductase (MTHFR) gene polymorphism ...

Evaluation of respiratory pattern during respiratory-gated radiotherapy

International Nuclear Information System (INIS)

Dobashi, Suguru; Mori, Shinichiro

2014-01-01

The respiratory cycle is not strictly regular, and generally varies in amplitude and period from one cycle to the next. We evaluated the characteristics of respiratory patterns acquired during respiratory gating treatment in more than 300 patients. A total 331 patients treated with respiratory-gated carbon-ion beam therapy were selected from a group of patients with thoracic and abdominal conditions. Respiratory data were acquired for a total of 3,171 fractions using an external respiratory sensing monitor and evaluated for respiratory cycle, duty cycle, magnitude of baseline drift, and intrafractional/interfractional peak inhalation/exhalation positional variation. Results for the treated anatomical sites and patient positioning were compared. Mean ± SD respiratory cycle averaged over all patients was 4.1 ± 1.3 s. Mean ± SD duty cycle averaged over all patients was 36.5 ± 7.3 %. Two types of baseline drift were seen, the first decremental and the second incremental. For respiratory peak variation, the mean intrafractional variation in peak-inhalation position relative to the amplitude in the first respiratory cycle (15.5 ± 9.3 %) was significantly larger than that in exhalation (7.5 ± 4.6 %). Interfractional variations in inhalation (17.2 ± 18.5 %) were also significantly greater than those in exhalation (9.4 ± 10.0 %). Statistically significant differences were observed between patients in the supine position and those in the prone position in mean respiratory cycle, duty cycle, and intra-/interfractional variations. We quantified the characteristics of the respiratory curve based on a large number of respiratory data obtained during treatment. These results might be useful in improving the accuracy of respiratory-gated treatment.

Rhizosphere colonization and arsenic translocation in sunflower (Helianthus annuus L.) by arsenate reducing Alcaligenes sp. strain Dhal-L.

Science.gov (United States)

Cavalca, Lucia; Corsini, Anna; Bachate, Sachin Prabhakar; Andreoni, Vincenza

2013-10-01

In the present study, six arsenic-resistant strains previously isolated were tested for their plant growth promoting characteristics and heavy metal resistance, in order to choose one model strain as an inoculum for sunflower plants in pot experiments. The aim was to investigate the effect of arsenic-resistant strain on sunflower growth and on arsenic uptake from arsenic contaminated soil. Based on plant growth promoting characteristics and heavy metal resistance, Alcaligenes sp. strain Dhal-L was chosen as an inoculum. Beside the ability to reduce arsenate to arsenite via an Ars operon, the strain exhibited 1-amino-cyclopropane-1-carboxylic acid deaminase activity and it was also able to produce siderophore and indole acetic acid. Pot experiments were conducted with an agricultural soil contaminated with arsenic (214 mg kg⁻¹). A real time PCR method was set up based on the quantification of ACR3(2) type of arsenite efflux pump carried by Alcaligenes sp. strain Dhal-L, in order to monitor presence and colonisation of the strain in the bulk and rhizospheric soil. As a result of strain inoculation, arsenic uptake by plants was increased by 53 %, whereas ACR3(2) gene copy number in rhizospheric soil was 100 times higher in inoculated than in control pots, indicating the colonisation of strain. The results indicated that the presence of arsenate reducing strains in the rhizosphere of sunflower influences arsenic mobilization and promotes arsenic uptake by plant.

Characterization of human warfarin reductase

OpenAIRE

Sokolová, Simona

2016-01-01

Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biochemical Sciences Candidate: Simona Sokolová Supervisor: PharmDr. Petra Malátková, Ph.D. Title of diploma thesis: Characterization of human warfarin reductase Warfarin is widely used anticoagulant drug. Considering the narrow therapeutic window of warfarin, it is important to fully understand its metabolism in human body. Oxidative, reductive and conjugation reactions are involved in warfarin metabolism. Howev...

Effects of dietary coenzyme Q10 supplementation on hepatic mitochondrial function and the activities of respiratory chain-related enzymes in ascitic broiler chickens.

Science.gov (United States)

Geng, A L; Guo, Y M

2005-10-01

1. One hundred and sixty 1-d-old Arbor Acre male broiler chicks were fed with maize-soybean based diets for 6 weeks in a 2 x 2 factorial experiment. The factors were CoQ10 supplementation (0 or 40 mg/kg) and Escherichia coli lipopolysaccharide (LPS) challenge (LPS or saline). 2. CoQ10 was supplemented from d 1. From d 18, the chickens received three weekly i.p. injections of LPS (1.0 mg/kg BW) or an equivalent amount of sterile saline as control. From d 10 on, all chickens were exposed to low ambient temperature (12 to 15 degrees C) to induce ascites. 3. The blood packed cell volume and ascites heart index of broiler chickens were reduced by dietary CoQ10 supplementation. Mitochondrial State 3 and State 4 respiration, respiratory control ratio and phosphate oxygen ratio were not changed, but H+/site stoichiometry of complex II + III was elevated by dietary CoQ10 supplementation. 4. Cytochrome c oxidase and H+-ATPase activity were increased by CoQ10 supplementation, whereas NADH cytochrome c reductase and succinate cytochrome c reductase were not influenced. Mitochondrial anti-ROS capability was increased and malondialdehyde content was decreased by CoQ10 supplementation. 5. The work suggested that dietary CoQ10 supplementation could reduce broiler chickens' susceptibility to ascites, which might be the result of improving hepatic mitochondrial function, some respiratory chain-related enzymes activities and mitochondrial antioxidative capability.

COMPARATIVE TISSUE DISTRIBUTION AND URINARY EXCRETION OF INORGANIC ARSENIC (IAS) AND ITS METHYLATED METABOLITES IN MICE FOLLOWING ORAL ADMINISTRATION OF ARSENATE (ASV) AND ARSENITE (ASIII)

Science.gov (United States)

COMPARATIVE TISSUE DISTRIBUTION AND URINARY EXCRETION OF INORGANIC ARSENIC (iAs) AND ITS METHYLATED METABOLITES IN MICE FOLLOWING ORAL ADMINISTRATION OF ARSENATE (AsV) AND ARSENITE (AsIII). E M Kenyon, L M Del Razo and M F Hughes. U.S. EPA, ORD, NHEERL, ETD, PKB, RTP, NC, USA; ...

Heliox reduces respiratory system resistance in respiratory syncytial virus induced respiratory failure

NARCIS (Netherlands)

Kneyber, Martin C. J.; van Heerde, Marc; Twisk, Jos W. R.; Plotz, Frans B.; Markhors, Dick G.

2009-01-01

Introduction Respiratory syncytial virus (RSV) lower respiratory tract disease is characterised by narrowing of the airways resulting in increased airway resistance, air-trapping and respiratory acidosis. These problems might be overcome using helium-oxygen gas mixture. However, the effect of

Heliox reduces respiratory system resistance in respiratory syncytial virus induced respiratory failure

NARCIS (Netherlands)

Kneijber, M.C.J.; van Heerde, M.; Twisk, J.W.R.; Plotz, F.; Markhorst, D.G.

2009-01-01

Introduction: Respiratory syncytial virus (RSV) lower respiratory tract disease is characterised by narrowing of the airways resulting in increased airway resistance, air-trapping and respiratory acidosis. These problems might be overcome using helium-oxygen gas mixture. However, the effect of

Inhibitory effect of rhetsinine isolated from Evodia rutaecarpa on aldose reductase activity.

Science.gov (United States)

Kato, A; Yasuko, H; Goto, H; Hollinshead, J; Nash, R J; Adachi, I

2009-03-01

Aldose reductase inhibitors have considerable potential for the treatment of diabetic complications, without increased risk of hypoglycemia. Search for components inhibiting aldose reductase led to the discovery of active compounds contained in Evodia rutaecarpa Bentham (Rutaceae), which is the one of the component of Kampo-herbal medicine. The hot water extract from the E. rutaecarpa was subjected to distribution or gel filtration chromatography to give an active compound, N2-(2-methylaminobenzoyl)tetrahydro-1H-pyrido[3,4-b]indol-1-one (rhetsinine). It inhibited aldose reductase with IC(50) values of 24.1 microM. Furthermore, rhetsinine inhibited sorbitol accumulation by 79.3% at 100 microM. These results suggested that the E. rutaecarpa derived component, rhetsinine, would be potentially useful in the treatment of diabetic complications.

Resolution of two native monomeric 90 kDa nitrate reductase active proteins from Shewanella gelidimarina and the sequence of two napA genes

International Nuclear Information System (INIS)

Simpson, Philippa J.L.; McKinzie, Audra A.; Codd, Rachel

2010-01-01

Research highlights: → Two monomeric 90 kDa nitrate reductase active proteins from Shewanella gelidimarina. → Sequence of napA from napEDABC-type operon and napA from NapDAGHB-type operon. → Isolation of NAP as NapA or NapAB correlated with NapA P47E amino acid substitution. -- Abstract: The reduction of nitrate to nitrite in the bacterial periplasm occurs in the 90 kDa NapA subunit of the periplasmic nitrate reductase (NAP) system. Most Shewanella genomes contain two nap operons: napEDABC and napDAGHB, which is an unusual feature of this genus. Two native, monomeric, 90 kDa nitrate reductase active proteins were resolved by hydrophobic interaction chromatography from aerobic cultures of Shewanella gelidimarina replete with reduced nitrogen compounds. The 90 kDa protein obtained in higher yield was characterized as NapA by electronic absorption and electron paramagnetic resonance spectroscopies and was identified by LC/MS/MS and MALDI-TOF/TOF MS as NapA from the napEDABC-type operon. The other 90 kDa protein, which was unstable and produced in low yields, was posited as NapA from the napDAGHB-type operon. Two napA genes have been sequenced from the napEDABC-type and napDAGHB-type operons of S. gelidimarina. Native NAP from S. putrefaciens was resolved as one NapA monomer and one NapAB heterodimer. Two amino acid substitutions in NapA correlated with the isolation of NAP as a NapA monomer or a NapAB heterodimer. The resolution of native, redox-active NapA isoforms in Shewanella provides new insight into the respiratory versatility of this genus, which has implications in bioremediation and the assembly of microbial fuel cells.

Sorptive removal of arsenate using termite mound.

Science.gov (United States)

Fufa, Fekadu; Alemayehu, Esayas; Lennartz, Bernd

2014-01-01

Long-term consumption of arsenic results in severe and permanent health damages. The aim of the study was to investigate arsenate (As(V)) sorption capacity of termite mound (TM), containing mainly silicon, aluminum, iron and titanium oxides, under batch adsorption setup. The pattern of As(V) removal with varying contact time, solution pH, adsorbent dose, As(V) concentration and competing anions was investigated. Dissolution of the adsorbent was insignificant under the equilibrium conditions. Equilibrium was achieved within 40 min of agitation time. Kinetic data of As(V) adsorption followed well the pseudo-second order equation (R(2) > 0.99). High As(V) removal efficiency (∼ 99%) was observed over a pH range ∼ 3-∼ 10, which is of great importance in the practical application. The Freundlich and Dubinin-Radushkevich isotherms well described (R(2) > 0.99, χ(2) ∼ 0.05) the equilibrium As(V) adsorption, giving a coefficient of adsorption 1.48 mg(1-1/n)L(1/n)/g and a saturation capacity 13.50 mg/g respectively. The obtained value of mean sorption energy (EDR = 13.32 kJ/mol) suggested the chemisorption mechanism of As(V) adsorption on TM. The removal of As(V) was significantly decreased in the presence of phosphate ions. The As(V) loaded adsorbent was successfully regenerated using NaOH solution with insignificant loss of metals. Therefore, the results of the study demonstrated that TM could be considered as a promising adsorbent for the treatment of As(V) in drinking water. Copyright © 2013 Elsevier Ltd. All rights reserved.

A study on the coprecipitation of arsenite and arsenate into calcite coupled with the determination of oxidation states of arsenic both in calcite and water

International Nuclear Information System (INIS)

Yokoyama, Yuka; Takahashi, Yoshio; Mitsunobu, Satoshi; Tanaka, Kazuya; Itai, Takaaki

2009-01-01

It was found that the amount of arsenite incorporated into calcite is much less than that of arsenate. The result suggests that the sequestration of arsenic by coprecipitation with calcite cannot be an important chemical process under reducing conditions such as in groundwater where arsenite is the dominant arsenic species. (author)

21 CFR 864.7375 - Glutathione reductase assay.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Glutathione reductase assay. 864.7375 Section 864.7375 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7375 Glutathione...

Characterisation of a desmosterol reductase involved in phytosterol dealkylation in the silkworm, Bombyx mori.

Directory of Open Access Journals (Sweden)

Leonora F Ciufo

Full Text Available Most species of invertebrate animals cannot synthesise sterols de novo and many that feed on plants dealkylate phytosterols (mostly C(29 and C(28 yielding cholesterol (C(27. The final step of this dealkylation pathway involves desmosterol reductase (DHCR24-catalysed reduction of desmosterol to cholesterol. We now report the molecular characterisation in the silkworm, Bombyx mori, of such a desmosterol reductase involved in production of cholesterol from phytosterol, rather than in de novo synthesis of cholesterol. Phylogenomic analysis of putative desmosterol reductases revealed the occurrence of various clades that allowed for the identification of a strong reductase candidate gene in Bombyx mori (BGIBMGA 005735. Following PCR-based cloning of the cDNA (1.6 kb and its heterologous expression in Saccharomyces cerevisae, the recombinant protein catalysed reduction of desmosterol to cholesterol in an NADH- and FAD-dependent reaction.Conceptual translation of the cDNA, that encodes a 58.9 kDa protein, and database searching, revealed that the enzyme belongs to an FAD-dependent oxidoreductase family. Western blotting revealed reductase protein expression exclusively in the microsomal subcellular fraction and primarily in the gut. The protein is peripherally associated with microsomal membranes. 2D-native gel and PAGE analysis revealed that the reductase is part of a large complex with molecular weight approximately 250 kDa. The protein occurs in midgut microsomes at a fairly constant level throughout development in the last two instars, but is drastically reduced during the wandering stage in preparation for metamorphosis. Putative Broad Complex transcription factor-binding sites detectable upstream of the DHCR24 gene may play a role in this down-regulation.

Characterisation of a Desmosterol Reductase Involved in Phytosterol Dealkylation in the Silkworm, Bombyx mori

Science.gov (United States)

Ciufo, Leonora F.; Murray, Patricia A.; Thompson, Anu; Rigden, Daniel J.; Rees, Huw H.

2011-01-01

Most species of invertebrate animals cannot synthesise sterols de novo and many that feed on plants dealkylate phytosterols (mostly C29 and C28) yielding cholesterol (C27). The final step of this dealkylation pathway involves desmosterol reductase (DHCR24)-catalysed reduction of desmosterol to cholesterol. We now report the molecular characterisation in the silkworm, Bombyx mori, of such a desmosterol reductase involved in production of cholesterol from phytosterol, rather than in de novo synthesis of cholesterol. Phylogenomic analysis of putative desmosterol reductases revealed the occurrence of various clades that allowed for the identification of a strong reductase candidate gene in Bombyx mori (BGIBMGA 005735). Following PCR-based cloning of the cDNA (1.6 kb) and its heterologous expression in Saccharomyces cerevisae, the recombinant protein catalysed reduction of desmosterol to cholesterol in an NADH- and FAD- dependent reaction. Conceptual translation of the cDNA, that encodes a 58.9 kDa protein, and database searching, revealed that the enzyme belongs to an FAD-dependent oxidoreductase family. Western blotting revealed reductase protein expression exclusively in the microsomal subcellular fraction and primarily in the gut. The protein is peripherally associated with microsomal membranes. 2D-native gel and PAGE analysis revealed that the reductase is part of a large complex with molecular weight approximately 250kDa. The protein occurs in midgut microsomes at a fairly constant level throughout development in the last two instars, but is drastically reduced during the wandering stage in preparation for metamorphosis. Putative Broad Complex transcription factor-binding sites detectable upstream of the DHCR24 gene may play a role in this down-regulation. PMID:21738635

Inhibition of human anthracycline reductases by emodin — A possible remedy for anthracycline resistance

International Nuclear Information System (INIS)

Hintzpeter, Jan; Seliger, Jan Moritz; Hofman, Jakub; Martin, Hans-Joerg; Wsol, Vladimir; Maser, Edmund

2016-01-01

The clinical application of anthracyclines, like daunorubicin and doxorubicin, is limited by two factors: dose-related cardiotoxicity and drug resistance. Both have been linked to reductive metabolism of the parent drug to their metabolites daunorubicinol and doxorubicinol, respectively. These metabolites show significantly less anti-neoplastic properties as their parent drugs and accumulate in cardiac tissue leading to chronic cardiotoxicity. Therefore, we aimed to identify novel and potent natural inhibitors for anthracycline reductases, which enhance the anticancer effect of anthracyclines by preventing the development of anthracycline resistance. Human enzymes responsible for the reductive metabolism of daunorubicin were tested for their sensitivity towards anthrachinones, in particular emodin and anthraflavic acid. Intense inhibition kinetic data for the most effective daunorubicin reductases, including IC 50 - and K i -values, the mode of inhibition, as well as molecular docking, were compiled. Subsequently, a cytotoxicity profile and the ability of emodin to reverse daunorubicin resistance were determined using multiresistant A549 lung cancer and HepG2 liver cancer cells. Emodin potently inhibited the four main human daunorubicin reductases in vitro. Further, we could demonstrate that emodin is able to synergistically sensitize human cancer cells towards daunorubicin at clinically relevant concentrations. Therefore, emodin may yield the potential to enhance the therapeutic effectiveness of anthracyclines by preventing anthracycline resistance via inhibition of the anthracycline reductases. In symphony with its known pharmacological properties, emodin might be a compound of particular interest in the management of anthracycline chemotherapy efficacy and their adverse effects. - Highlights: • Natural and synthetic compounds were identified as inhibitors for human daunorubicin reductases. • Emodin is a potent inhibitor for human daunorubicin reductases. �

Colour formation in fermented sausages by meat-associated staphylococci with different nitrite- and nitrate-reductase activities

DEFF Research Database (Denmark)

Gøtterup, Jacob; Olsen, Karsten; Knøchel, Susanne

2008-01-01

nitrate depended on the specific Staphylococcus strain. Strains with high nitrate-reductase activity showed a significantly faster rate of pigment formation, but other factors were of influence as well. Product stability for the sliced, packaged sausage was evaluated as surface colour and oxidation......Three Staphylococcus strains, S. carnosus, S. simulans and S. saprophyticus, selected due to their varying nitrite and/or nitrate-reductase activities, were used to initiate colour formation during sausage fermentation. During fermentation of sausages with either nitrite or nitrate added, colour...... with hexanal content, and may be used as predictive tools. Overall, nitrite- and nitrate-reductase activities of Staphylococcus strains in nitrite-cured sausages were of limited importance regarding colour development, while in nitrate-cured sausages strains with higher nitrate reductase activity were crucial...

Environmental Risks of Nano Zerovalent Iron for Arsenate Remediation: Impacts on Cytosolic Levels of Inorganic Phosphate and MgATP2- in Arabidopsis thaliana.

Science.gov (United States)

Zhang, Weilan; Lo, Irene M C; Hu, Liming; Voon, Chia Pao; Lim, Boon Leong; Versaw, Wayne K

2018-04-03

The use of nano zerovalent iron (nZVI) for arsenate (As(V)) remediation has proven effective, but full-scale injection of nZVI into the subsurface has aroused serious concerns for associated environmental risks. This study evaluated the efficacy of nZVI treatment for arsenate remediation and its potential hazards to plants using Arabidopsis thaliana grown in a hydroponic system. Biosensors for inorganic phosphate (Pi) and MgATP 2- were used to monitor in vivo Pi and MgATP 2- levels in plant cells. The results showed that nZVI could remove As(V) from growth media, decrease As uptake by plants, and mitigate As(V) toxicity to plants. However, excess nZVI could cause Pi starvation in plants leading to detrimental effects on plant growth. Due to the competitive adsorption of As(V) and Pi on nZVI, removing As(V) via nZVI treatment at an upstream site could relieve downstream plants from As(V) toxicity and Pi deprivation, in which case 100 mg/L of nZVI was the optimal dosage for remediation of As(V) at a concentration around 16.13 mg/L.

Aldose Reductase Inhibitory and Antiglycation Activities of Four ...

African Journals Online (AJOL)

Aldose Reductase Inhibitory and Antiglycation Activities of Four Medicinal Plant Standardized Extracts and Their Main Constituents for the Prevention of ... levels in galactosemic condition by using reverse phase high pressure liquid chromatography (RP-HPLC) and gas liquid chromatography (GLC) was determined.

Xylose reductase from the thermophilic fungus Talaromyces emersonii

Indian Academy of Sciences (India)

Prakash

Xylose reductase is involved in the first step of the fungal pentose catabolic pathway. The gene .... proteins with reversed coenzyme preference from NADPH to NADH ..... 399–404. Hasper A A, Visser J and de Graaff L H 2000 The Aspergillus.

Regulation of schistosome egg production by HMG CoA reductase

International Nuclear Information System (INIS)

VandeWaa, E.A.; Bennett, J.L.

1986-01-01

Hydroxymethylglutaryl coenzyme A reductase (HMG CoA reductase) catalyzes the conversion of HMG CoA to mevalonate in the synthesis of steroids, isoprenoids and terpenes. Mevinolin, an inhibitor of this enzyme, decreased egg production in Schistosoma mansoni during in vitro incubations. This was associated with a reduction in the incorporation of 14 C-acetate into polyisoprenoids and a reduction in the formation of a lipid-linked oligosaccharide. In vivo, mevinolin in daily doses of 50 mg/kg (p.o., from days 30-48 post-infection) caused no change in gross liver pathology in S. mansoni infected mice. However, when parasites exposed to mevinolin or its vehicle in vivo were cultured in vitro, worms from mevinolin-treated mice produced six times more eggs than control parasites. When infected mice were dosed with 250 mg/kg mevinolin daily (p.o., from days 35-45 post-infection), liver pathology was reduced in comparison to control mice. Thus, during in vivo exposure to a high dose of the drug egg production is decreased, while at a lower dose it appears unaffected until the parasites are cultured in a drug-free in vitro system wherein egg production is stimulated to extraordinarily high levels. It may be that at low doses mevinolin, by inhibiting the enzyme, is blocking the formation of a product (such as an isoprenoid) which normally acts to down-regulate enzyme synthesis, resulting in enzyme induction. Induction of HMG CoA reductase is then expressed as increased egg production when the worms are removed from the drug. These data suggest that HMG CoA reductase plays a role in schistosome egg production

Inhibition of aldose reductase activity by Cannabis sativa chemotypes extracts with high content of cannabidiol or cannabigerol.

Science.gov (United States)

Smeriglio, Antonella; Giofrè, Salvatore V; Galati, Enza M; Monforte, Maria T; Cicero, Nicola; D'Angelo, Valeria; Grassi, Gianpaolo; Circosta, Clara

2018-02-07

Aldose reductase (ALR2) is a key enzyme involved in diabetic complications and the search for new aldose reductase inhibitors (ARIs) is currently very important. The synthetic ARIs are often associated with deleterious side effects and medicinal and edible plants, containing compounds with aldose reductase inhibitory activity, could be useful for prevention and therapy of diabetic complications. Non-psychotropic phytocannabinoids exert multiple pharmacological effects with therapeutic potential in many diseases such as inflammation, cancer, diabetes. Here, we have investigated the inhibitory effects of extracts and their fractions from two Cannabis sativa L. chemotypes with high content of cannabidiol (CBD)/cannabidiolic acid (CBDA) and cannabigerol (CBG)/cannabigerolic acid (CBGA), respectively, on human recombinant and pig kidney aldose reductase activity in vitro. A molecular docking study was performed to evaluate the interaction of these cannabinoids with the active site of ALR2 compared to known ARIs. The extracts showed significant dose-dependent aldose reductase inhibitory activity (>70%) and higher than fractions. The inhibitory activity of the fractions was greater for acidic cannabinoid-rich fractions. Comparative molecular docking results have shown a higher stability of the ALR2-cannabinoid acids complex than the other inhibitors. The extracts of Cannabis with high content of non-psychotropic cannabinoids CBD/CBDA or CBG/CBGA significantly inhibit aldose reductase activity. These results may have some relevance for the possible use of C. sativa chemotypes based preparations as aldose reductase inhibitors. Copyright © 2018 Elsevier B.V. All rights reserved.

JS-K, a Nitric Oxide Prodrug, Has Enhanced Cytotoxicity in Colon Cancer Cells with Knockdown of Thioredoxin Reductase 1

Science.gov (United States)

Edes, Kornelia; Cassidy, Pamela; Shami, Paul J.; Moos, Philip J.

2010-01-01

Background The selenoenzyme thioredoxin reductase 1 has a complex role relating to cell growth. It is induced as a component of the cellular response to potentially mutagenic oxidants, but also appears to provide growth advantages to transformed cells by inhibiting apoptosis. In addition, selenocysteine-deficient or alkylated forms of thioredoxin reductase 1 have also demonstrated oxidative, pro-apoptotic activity. Therefore, a greater understanding of the role of thioredoxin reductase in redox initiated apoptotic processes is warranted. Methodology The role of thioredoxin reductase 1 in RKO cells was evaluated by attenuating endogenous thioredoxin reductase 1 expression with siRNA and then either inducing a selenium-deficient thioredoxin reductase or treatment with distinct redox challenges including, hydrogen peroxide, an oxidized lipid, 4-hydroxy-2-nonenol, and a nitric oxide donating prodrug. Thioredoxin redox status, cellular viability, and effector caspase activity were measured. Conclusions/Significance In cells with attenuated endogenous thioredoxin reductase 1, a stably integrated selenocysteine-deficient form of the enzyme was induced but did not alter either the thioredoxin redox status or the cellular growth kinetics. The oxidized lipid and the nitric oxide donor demonstrated enhanced cytotoxicity when thioredoxin reductase 1 was knocked-down; however, the effect was more pronounced with the nitric oxide prodrug. These results are consistent with the hypothesis that attenuation of the thioredoxin-system can promote apoptosis in a nitric oxide-dependent manner. PMID:20098717

Inhibition of human anthracycline reductases by emodin — A possible remedy for anthracycline resistance

Energy Technology Data Exchange (ETDEWEB)

Hintzpeter, Jan, E-mail: hintzpeter@toxi.uni-kiel.de [Institute of Toxicology and Pharmacology for Natural Scientists, University Medical School Schleswig-Holstein, Campus Kiel, Brunswiker Str. 10, 24105 Kiel (Germany); Seliger, Jan Moritz [Institute of Toxicology and Pharmacology for Natural Scientists, University Medical School Schleswig-Holstein, Campus Kiel, Brunswiker Str. 10, 24105 Kiel (Germany); Hofman, Jakub [Department of Biochemical Sciences, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, 50005 Hradec Kralove (Czech Republic); Martin, Hans-Joerg [Institute of Toxicology and Pharmacology for Natural Scientists, University Medical School Schleswig-Holstein, Campus Kiel, Brunswiker Str. 10, 24105 Kiel (Germany); Wsol, Vladimir [Department of Biochemical Sciences, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, 50005 Hradec Kralove (Czech Republic); Maser, Edmund [Institute of Toxicology and Pharmacology for Natural Scientists, University Medical School Schleswig-Holstein, Campus Kiel, Brunswiker Str. 10, 24105 Kiel (Germany)

2016-02-15

The clinical application of anthracyclines, like daunorubicin and doxorubicin, is limited by two factors: dose-related cardiotoxicity and drug resistance. Both have been linked to reductive metabolism of the parent drug to their metabolites daunorubicinol and doxorubicinol, respectively. These metabolites show significantly less anti-neoplastic properties as their parent drugs and accumulate in cardiac tissue leading to chronic cardiotoxicity. Therefore, we aimed to identify novel and potent natural inhibitors for anthracycline reductases, which enhance the anticancer effect of anthracyclines by preventing the development of anthracycline resistance. Human enzymes responsible for the reductive metabolism of daunorubicin were tested for their sensitivity towards anthrachinones, in particular emodin and anthraflavic acid. Intense inhibition kinetic data for the most effective daunorubicin reductases, including IC{sub 50}- and K{sub i}-values, the mode of inhibition, as well as molecular docking, were compiled. Subsequently, a cytotoxicity profile and the ability of emodin to reverse daunorubicin resistance were determined using multiresistant A549 lung cancer and HepG2 liver cancer cells. Emodin potently inhibited the four main human daunorubicin reductases in vitro. Further, we could demonstrate that emodin is able to synergistically sensitize human cancer cells towards daunorubicin at clinically relevant concentrations. Therefore, emodin may yield the potential to enhance the therapeutic effectiveness of anthracyclines by preventing anthracycline resistance via inhibition of the anthracycline reductases. In symphony with its known pharmacological properties, emodin might be a compound of particular interest in the management of anthracycline chemotherapy efficacy and their adverse effects. - Highlights: • Natural and synthetic compounds were identified as inhibitors for human daunorubicin reductases. • Emodin is a potent inhibitor for human daunorubicin

Cloning and sequence of the human adrenodoxin reductase gene

International Nuclear Information System (INIS)

Lin, Dong; Shi, Y.; Miller, W.L.

1990-01-01

Adrenodoxin reductase is a flavoprotein mediating electron transport to all mitochondrial forms of cytochrome P450. The authors cloned the human adrenodoxin reductase gene and characterized it by restriction endonuclease mapping and DNA sequencing. The entire gene is approximately 12 kilobases long and consists of 12 exons. The first exon encodes the first 26 of the 32 amino acids of the signal peptide, and the second exon encodes the remainder of signal peptide and the apparent FAD binding site. The remaining 10 exons are clustered in a region of only 4.3 kilobases, separated from the first two exons by a large intron of about 5.6 kilobases. Two forms of human adrenodoxin reductase mRNA, differing by the presence or absence of 18 bases in the middle of the sequence, arise from alternate splicing at the 5' end of exon 7. This alternately spliced region is directly adjacent to the NADPH binding site, which is entirely contained in exon 6. The immediate 5' flanking region lacks TATA and CAAT boxes; however, this region is rich in G+C and contains six copies of the sequence GGGCGGG, resembling promoter sequences of housekeeping genes. RNase protection experiments show that transcription is initiated from multiple sites in the 5' flanking region, located about 21-91 base pairs upstream from the AUG translational initiation codon

Structural and biochemical properties of cloned and expressed human and rat steroid 5α-reductases

International Nuclear Information System (INIS)

Andersson, S.; Russell, D.W.

1990-01-01

The microsomal enzyme steroid 5α-reductase is responsible for the conversion of testosterone into the more potent androgen dihydrotestosterone. In man, this steroid acts on a variety of androgen-responsive target tissues to mediate such diverse endocrine processes as male sexual differentiation in the fetus and prostatic growth in men. Here we describe the isolation, structure, and expression of a cDNA encoding the human steroid 5α-reductase. A rat cDNA was used as a hybridization probe to screen a human prostate cDNA library. A 2.1-kilobase cDNA was identified and DNA sequence analysis indicated that the human steroid 5α-reductase was a hydrophobic protein of 259 amino acids with a predicted molecular weight of 29,462. A comparison of the human and rat protein sequences revealed a 60% identity. Transfection of expression vectors containing the human and rat cDNAs into simian COS cells resulted in the synthesis of high levels of steroid 5α-reductase enzyme activity. Both enzymes expressed in COS cells showed similar substrate specificities for naturally occurring steroid hormones. However, synthetic 4-azasteroids demonstrated marked differences in their abilities to inhibit the human and rat steroid 5α-reductases

Overview of Catalytic Properties of Fungal Xylose Reductases and Molecular Engineering Approaches for Improved Xylose Utilisation in Yeast

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Sk Amir Hossain

2018-03-01

Full Text Available Background and Objective: Xylose reductases belong to the aldo-keto reductase family of enzymes, which catalyse the conversion of xylose to xylitol. Yeast xylose reductases have been intensively studied in the last two decades due to their significance in biotechnological production of ethanol and xylitol from xylose. Due to its GRAS status and pronounced tolerance to harsh conditions, Saccharomyces cerevisiae is the ideal organism for industrial production of both xylitol and ethanol. However, Saccharomyces cerevisiae is unable to use xylose as the sole carbon source due to the lack of xylose specific transporters and insufficient activity of metabolic pathways for xylose utilisation. The aim of this paper is to give an overview of attempts in increasing biotechnological potential of xylose reductases and to highlight the prospective of this application. Results and Conclusion: In order to create strains with improved xylose utilization, different approaches were attempted including simultaneous overexpression of xylitol dehydrogenase, xylose reductase and pentose phosphate pathway enzymes, heterologous expression of putative xylose transporters or heterologous expression of genes coding for enzymes included in the xylose metabolism, respectively. Furthermore, number of attempts to genetically modify different xylose reductases is increasing. This review presents current knowledge about yeast xylose reductases and the different approaches applied in order to improve xylose metabolism in yeast.Conflict of interest: The authors declare no conflict of interest.

Aldose Reductase Inhibitory Activity of Compounds from  Zea mays L.

Science.gov (United States)

Kim, Tae Hyeon; Kim, Jin Kyu; Kang, Young-Hee; Lee, Jae-Yong; Kang, Il Jun; Lim, Soon Sung

2013-01-01

Aldose reductase (AR) inhibitors have a considerable therapeutic potential against diabetes complications and do not increase the risk of hypoglycemia. Through bioassay-guided fractionation of an EtOH extract of the kernel from purple corn (Zea mays L.), 7 nonanthocyanin phenolic compounds (compound 1–7) and 5 anthocyanins (compound 8–12) were isolated. These compounds were investigated by rat lens aldose reductase (RLAR) inhibitory assays. Kinetic analyses of recombinant human aldose reductase (rhAR) were performed, and intracellular galactitol levels were measured. Hirsutrin, one of 12 isolated compounds, showed the most potent RLAR inhibitory activity (IC50, 4.78 μM). In the kinetic analyses using Lineweaver-Burk plots of 1/velocity and 1/substrate concentration, hirsutrin showed competitive inhibition against rhAR. Furthermore, hirsutrin inhibited galactitol formation in rat lens and erythrocytes sample incubated with a high concentration of galactose; this finding indicates that hirsutrin may effectively prevent osmotic stress in hyperglycemia. Therefore, hirsutrin derived from Zea mays L. may be a potential therapeutic agent against diabetes complications. PMID:23586057

Characterization of a cultured human T-cell line with genetically altered ribonucleotide reductase activity. Model for immunodeficiency.

Science.gov (United States)

Waddell, D; Ullman, B

1983-04-10

From human CCRF-CEM T-cells growing in continuous culture, we have selected, isolated, and characterized a clonal cell line, APHID-D2, with altered ribonucleotide reductase activity. In comparative growth rate experiments, the APHID-D2 cell line is less sensitive than the parental cell line to growth inhibition by deoxyadenosine in the presence of 10 microM erythro-9-(2-hydroxy-3-nonyl)adenine, an inhibitor of adenosine deaminase. The APHID-D2 cell line has elevated levels of all four dNTPs. The resistance of the APHID-D2 cell line to growth inhibition by deoxyadenosine and the abnormal dNTP levels can be explained by the fact that the APHID-D2 ribonucleotide reductase, unlike the parental ribonucleotide reductase, is not normally sensitive to inhibition by dATP. These results suggest that the allosteric site of ribonucleotide reductase which binds both dATP and ATP is altered in the APHID-D2 line. The isolation of a mutant clone of human T-cells which contains a ribonucleotide reductase that has lost its normal sensitivity to dATP and which is resistant to deoxyadenosine-mediated growth inhibition suggests that a primary pathogenic target of accumulated dATP in lymphocytes from patients with adenosine deaminase deficiency may be the cellular ribonucleotide reductase.

Plasmid-encoded diacetyl (acetoin) reductase in Leuconostoc pseudomesenteroides

DEFF Research Database (Denmark)

Rattray, Fergal P; Myling-Petersen, Dorte; Larsen, Dianna

2003-01-01

A plasmid-borne diacetyl (acetoin) reductase (butA) from Leuconostoc pseudomesenteroides CHCC2114 was sequenced and cloned. Nucleotide sequence analysis revealed an open reading frame encoding a protein of 257 amino acids which had high identity at the amino acid level to diacetyl (acetoin...

X-Ray crystal structure of GarR—tartronate semialdehyde reductase from Salmonella typhimurium

OpenAIRE

Osipiuk, J.; Zhou, M.; Moy, S.; Collart, F.; Joachimiak, A.

2009-01-01

Tartronate semialdehyde reductases (TSRs), also known as 2-hydroxy-3-oxopropionate reductases, catalyze the reduction of tartronate semialdehyde using NAD as cofactor in the final stage of D-glycerate biosynthesis. These enzymes belong to family of structurally and mechanically related β-hydroxyacid dehydrogenases which differ in substrate specificity and catalyze reactions in specific metabolic pathways. Here, we present the crystal structure of GarR a TSR from Salmonella typhimurium determi...

Reduced bone mass and muscle strength in male 5α-reductase type 1 inactivated mice.

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Sara H Windahl

Full Text Available Androgens are important regulators of bone mass but the relative importance of testosterone (T versus dihydrotestosterone (DHT for the activation of the androgen receptor (AR in bone is unknown. 5α-reductase is responsible for the irreversible conversion of T to the more potent AR activator DHT. There are two well established isoenzymes of 5α-reductase (type 1 and type 2, encoded by separate genes (Srd5a1 and Srd5a2. 5α-reductase type 2 is predominantly expressed in male reproductive tissues whereas 5α-reductase type 1 is highly expressed in liver and moderately expressed in several other tissues including bone. The aim of the present study was to investigate the role of 5α-reductase type 1 for bone mass using Srd5a1⁻/⁻ mice. Four-month-old male Srd5a1⁻/⁻ mice had reduced trabecular bone mineral density (-36%, p<0.05 and cortical bone mineral content (-15%, p<0.05 but unchanged serum androgen levels compared with wild type (WT mice. The cortical bone dimensions were reduced in the male Srd5a1⁻/⁻ mice as a result of a reduced cortical periosteal circumference compared with WT mice. T treatment increased the cortical periosteal circumference (p<0.05 in orchidectomized WT mice but not in orchidectomized Srd5a1⁻/⁻ mice. Male Srd5a1⁻/⁻ mice demonstrated a reduced forelimb muscle grip strength compared with WT mice (p<0.05. Female Srd5a1⁻/⁻ mice had slightly increased cortical bone mass associated with elevated circulating levels of androgens. In conclusion, 5α-reductase type 1 inactivated male mice have reduced bone mass and forelimb muscle grip strength and we propose that these effects are due to lack of 5α-reductase type 1 expression in bone and muscle. In contrast, the increased cortical bone mass in female Srd5a1⁻/⁻ mice, is an indirect effect mediated by elevated circulating androgen levels.

Effect of cystamine on rat tissue GSH level and glutathione reductase activity

International Nuclear Information System (INIS)

Kovarova, H.; Pulpanova, J.

1979-01-01

Reduced glutathione (GSH) level and glutathione reductase activity were determined by means of the spectrophotometric method in various rat tissues after i.p. administration of cystamine (50 mg/kg and 20 mg/kg). GSH amount dropped in the spleen and kidney at 10 and 20 min; following this interval, an increase of GSH level was observed in the liver at 20-30 min, in the spleen and kidney at 60 min after the treatment with a radioprotective cystamine dose (50 mg/kg). The changes in GSH level induced by a non-radioprotective cystamine dose (20 mg/kg) had an opposite tendency. The activity of glutathione reductase was decreased in all tissues studied. As to the mechanism of the radioprotective action, both the inactivation of glutathione reductase activity and the changes in GSH level seem to be the factors contributing to the radioprotective effect of cystamine by strengthening the cellular radioresistance. (orig.) 891 MG/orig. 892 RKD [de

Respiratory acidosis

Science.gov (United States)

Ventilatory failure; Respiratory failure; Acidosis - respiratory ... Causes of respiratory acidosis include: Diseases of the airways (such as asthma and COPD ) Diseases of the lung tissue (such as ...

Expression, purification, crystallization and preliminary X-ray diffraction analysis of carbonyl reductase from Candida parapsilosis ATCC 7330

International Nuclear Information System (INIS)

Aggarwal, Nidhi; Mandal, P. K.; Gautham, Namasivayam; Chadha, Anju

2013-01-01

The expression, purification, crystallization, preliminary X-ray diffraction and molecular-replacement studies on C. parapsilosis carbonyl reductase are reported. The NAD(P)H-dependent carbonyl reductase from Candida parapsilosis ATCC 7330 catalyses the asymmetric reduction of ethyl 4-phenyl-2-oxobutanoate to ethyl (R)-4-phenyl-2-hydroxybutanoate, a precursor of angiotensin-converting enzyme inhibitors such as Cilazapril and Benazepril. The carbonyl reductase was expressed in Escherichia coli and purified by GST-affinity and size-exclusion chromatography. Crystals were obtained by the hanging-drop vapour-diffusion method and diffracted to 1.86 Å resolution. The asymmetric unit contained two molecules of carbonyl reductase, with a solvent content of 48%. The structure was solved by molecular replacement using cinnamyl alcohol dehydrogenase from Saccharomyces cerevisiae as a search model

Proanthocyanidin synthesis in Theobroma cacao: genes encoding anthocyanidin synthase, anthocyanidin reductase, and leucoanthocyanidin reductase.

Science.gov (United States)

Liu, Yi; Shi, Zi; Maximova, Siela; Payne, Mark J; Guiltinan, Mark J

2013-12-05

The proanthocyanidins (PAs), a subgroup of flavonoids, accumulate to levels of approximately 10% total dry weight of cacao seeds. PAs have been associated with human health benefits and also play important roles in pest and disease defense throughout the plant. To dissect the genetic basis of PA biosynthetic pathway in cacao (Theobroma cacao), we have isolated three genes encoding key PA synthesis enzymes, anthocyanidin synthase (ANS), anthocyanidin reductase (ANR) and leucoanthocyanidin reductase (LAR). We measured the expression levels of TcANR, TcANS and TcLAR and PA content in cacao leaves, flowers, pod exocarp and seeds. In all tissues examined, all three genes were abundantly expressed and well correlated with PA accumulation levels, suggesting their active roles in PA synthesis. Overexpression of TcANR in an Arabidopsis ban mutant complemented the PA deficient phenotype in seeds and resulted in reduced anthocyanidin levels in hypocotyls. Overexpression of TcANS in tobacco resulted in increased content of both anthocyanidins and PAs in flower petals. Overexpression of TcANS in an Arabidopsis ldox mutant complemented its PA deficient phenotype in seeds. Recombinant TcLAR protein converted leucoanthocyanidin to catechin in vitro. Transgenic tobacco overexpressing TcLAR had decreased amounts of anthocyanidins and increased PAs. Overexpressing TcLAR in Arabidopsis ldox mutant also resulted in elevated synthesis of not only catechin but also epicatechin. Our results confirm the in vivo function of cacao ANS and ANR predicted based on sequence homology to previously characterized enzymes from other species. In addition, our results provide a clear functional analysis of a LAR gene in vivo.

Photoaffinity labeling of steroid 5 alpha-reductase of rat liver and prostate microsomes

International Nuclear Information System (INIS)

Liang, T.; Cheung, A.H.; Reynolds, G.F.; Rasmusson, G.H.

1985-01-01

21-Diazo-4-methyl-4-aza-5 alpha-pregnane-3,20-dione (Diazo-MAPD) inhibits steroid 5 alpha-reductase in liver microsomes of female rats with a K/sub i/ value of 8.7 +/- 1.7 nM, and the inhibition is competitive with testosterone. It also inhibits the binding of a 5 alpha-reductase inhibitor, [ 3 H] 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one ([ 3 H]4-MA), to the enzyme in liver microsomes. The inhibition of 5 alpha-reductase activity and of inhibitor binding activity by diazo-MAPD becomes irreversible upon UV irradiation. [1,2- 3 H]Diazo-MAPD binds to a single high affinity site in liver microsomes of female rats, and this binding requires NADPH. Without UV irradiation, this binding is reversible, and it becomes irreversible upon UV irradiation. Both the initial reversible binding and the subsequent irreversible conjugation after UV irradiation are inhibited by inhibitors (diazo-MAPD and 4-MA) and substrates (progesterone and testosterone) of 5 alpha-reductase, but they are not inhibited by 5 alpha-reduced steroids. Photoaffinity labeled liver microsomes of female rats were solubilized and fractionated by high performance gel filtration. The radioactive conjugate eluted in one major peak at Mr 50,000

Simulation of the effects of phosphate on adsorption of arsenite and arsenate on ferrihydrite matrix using a geochemical equilibrium model

International Nuclear Information System (INIS)

Kassenga, G.R.

2005-01-01

Arsenic is of environmental concern because of its toxicity to plants, animals, and human beings. Iron oxides, including the poorly crystalline (amorphous) iron oxides, e.g., ferrihydrite, have a strong affinity for both arsenite and arsenate (the most toxic species of arsenic). In view of this, adsorption on ferrihydrite matrix is the main process of immobilization of arsenic in groundwater. The presence of phosphate in groundwater may however limit adsorption of arsenic on iron oxides due to competition for adsorption sites, resulting in higher aqueous concentrations in some environments. This paper analyses the effects of phosphate on aqueous concentration of arsenic at different pH using a geochemical equilibrium simulation model. It specifically focuses on arsenite and arsenate, the most toxic forms of arsenic. A general description of the occurrence of arsenic in the environment, its toxicity, and health hazards is first given. The paper discusses sources and geochemical processes that control arsenic mobility in aquifers. Adsorption and desorption reactions of arsenic on ferrihydrite and the factors that affect them are described. Modeling of adsorption/desorption processes is then discussed. Finally, the effects of phosphate on adsorption and desorption processes of arsenic on ferrihydrite as a function of pH are analyzed using PHREEQC Version 2, a computer program for simulating chemical reactions and transport processes in natural and polluted water. The model is applied in a case study formulated on the basis of a realistic hydrogeochemical setting to demonstrate how the use of arsenical pesticides and phosphate fertilizers may pose potential public health problems in areas where groundwater is used for domestic purposes. The modeling results have shown that aqueous concentration of arsenic increases with increasing phosphate-phosphorus concentration for pH values less than 10 assuming that ferrihydrite concentration and other hydrogeochemical conditions

Hydroxyurea-Mediated Cytotoxicity Without Inhibition of Ribonucleotide Reductase.

Science.gov (United States)

Liew, Li Phing; Lim, Zun Yi; Cohen, Matan; Kong, Ziqing; Marjavaara, Lisette; Chabes, Andrei; Bell, Stephen D

2016-11-01

In many organisms, hydroxyurea (HU) inhibits class I ribonucleotide reductase, leading to lowered cellular pools of deoxyribonucleoside triphosphates. The reduced levels for DNA precursors is believed to cause replication fork stalling. Upon treatment of the hyperthermophilic archaeon Sulfolobus solfataricus with HU, we observe dose-dependent cell cycle arrest, accumulation of DNA double-strand breaks, stalled replication forks, and elevated levels of recombination structures. However, Sulfolobus has a HU-insensitive class II ribonucleotide reductase, and we reveal that HU treatment does not significantly impact cellular DNA precursor pools. Profiling of protein and transcript levels reveals modulation of a specific subset of replication initiation and cell division genes. Notably, the selective loss of the regulatory subunit of the primase correlates with cessation of replication initiation and stalling of replication forks. Furthermore, we find evidence for a detoxification response induced by HU treatment. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Nitrate reductase gene involvement in hexachlorobiphenyl dechlorination by Phanerochaete chrysosporium

International Nuclear Information System (INIS)

De, Supriyo; Perkins, Michael; Dutta, Sisir K.

2006-01-01

Polychlorobiphenyl (PCB) degradation usually occurs through reductive dechlorination under anaerobic conditions and phenolic ring cleavage under aerobic conditions. In this paper, we provide evidence of nitrate reductase (NaR) mediated dechlorination of hexachlorobiphenyl (PCB-153) in Phanerochaete chrysosporium under non-ligninolytic condition and the gene involved. The NaR enzyme and its cofactor, molybdenum (Mo), were found to mediate reductive dechlorination of PCBs even in aerobic condition. Tungsten (W), a competitive inhibitor of this enzyme, was found to suppress this dechlorination. Chlorine release assay provided further evidence of this nitrate reductase mediated dechlorination. Commercially available pure NaR enzyme from Aspergillus was used to confirm these results. Through homology search using TBLASTN program, NaR gene was identified, primers were designed and the RT-PCR product was sequenced. The NaR gene was then annotated in the P. chrysosporium genome (GenBank accession no. AY700576). This is the first report regarding the presence of nitrate reductase gene in this fungus with the explanation why this fungus can dechlorinate PCBs even in aerobic condition. These fungal inoculums are used commercially as pellets in sawdust for enhanced bioremediation of PCBs at the risk of depleting soil nitrates. Hence, the addition of nitrates to the pellets will reduce this risk as well as enhance its activity

Isolation and characterization of cDNAs encoding leucoanthocyanidin reductase and anthocyanidin reductase from Populus trichocarpa.

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Lijun Wang

Full Text Available Proanthocyanidins (PAs contribute to poplar defense mechanisms against biotic and abiotic stresses. Transcripts of PA biosynthetic genes accumulated rapidly in response to infection by the fungus Marssonina brunnea f.sp. multigermtubi, treatments of salicylic acid (SA and wounding, resulting in PA accumulation in poplar leaves. Anthocyanidin reductase (ANR and leucoanthocyanidin reductase (LAR are two key enzymes of the PA biosynthesis that produce the main subunits: (+-catechin and (--epicatechin required for formation of PA polymers. In Populus, ANR and LAR are encoded by at least two and three highly related genes, respectively. In this study, we isolated and functionally characterized genes PtrANR1 and PtrLAR1 from P. trichocarpa. Phylogenetic analysis shows that Populus ANR1 and LAR1 occurr in two distinct phylogenetic lineages, but both genes have little difference in their tissue distribution, preferentially expressed in roots. Overexpression of PtrANR1 in poplar resulted in a significant increase in PA levels but no impact on catechin levels. Antisense down-regulation of PtrANR1 showed reduced PA accumulation in transgenic lines, but increased levels of anthocyanin content. Ectopic expression of PtrLAR1 in poplar positively regulated the biosynthesis of PAs, whereas the accumulation of anthocyanin and flavonol was significantly reduced (P<0.05 in all transgenic plants compared to the control plants. These results suggest that both PtrANR1 and PtrLAR1 contribute to PA biosynthesis in Populus.

Isolation and primary structural analysis of two conjugated polyketone reductases from Candida parapsilosis.

Science.gov (United States)

Hidalgo, A R; Akond, M A; Kita, K; Kataoka, M; Shimizu, S

2001-12-01

Two conjugated polyketone reductases (CPRs) were isolated from Candida parapsilosis IFO 0708. The primary structures of CPRs (C1 and C2) were analyzed by amino acid sequencing. The amino acid sequences of both enzymes had high similarity to those of several proteins of the aldo-keto-reductase (AKR) superfamily. However, several amino acid residues in the putative active sites of AKRs were not conserved in CPRs-C1 and -C2.

Synthesis of calix[4]arene-grafted magnetite nanoparticles and Evaluation of their arsenate as well as dichromate removal efficiency

Energy Technology Data Exchange (ETDEWEB)

Sayin, Serkan; Ozcan, Fatih; Yilmaz, Mustafa; Cengeloglu, Yunus [Department of Chemistry, Selcuk University, Konya (Turkey); Tor, Ali [Department of Environmental Engineering, Selcuk University, Konya (Turkey); Memon, Shahabuddin [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro (Pakistan)

2010-07-15

In this study, 5,17-bis-[(4-benzylpiperidine)methyl]-25,26,27,28-tetrahydroxy-calix[4]arene (3) has been prepared by the treatment of calix[4]arene with a secondary amine (4-benzylpiperidine) and formaldehyde by means of Mannich reaction. The prepared Mannich base (3) has been grafted onto [3-(2,3-epoxypropoxy)-propyl]-trimethoxysilane-modified Fe{sub 3}O{sub 4} magnetite nanoparticles (EPPTMS-MN) in order to obtain 5,17-bis-[(4-benzylpiperidine)methyl]-25,26,27,28-tetrahydroxy calix[4]arene-grafted EPPTMS-MN (BP-calix[4]arene-grafted Fe{sub 3}O{sub 4}). All new compounds were characterized by a combination of FTIR and {sup 1}H-NMR analyses. The morphology of the magnetic nanoparticles was examined by transmission electron microscopy. Moreover, the studies regarding the removal of arsenate and dichromate ions from the aqueous solutions were also carried out by using 5,17-bis-[(4-benzylpiperidine)methyl]-25,26,27,28-tetrahydroxy-calix[4]arene in liquid-liquid extraction and BP-calix[4]arene-grafted Fe{sub 3}O{sub 4} (4) in solid-liquid extraction experiments. The extraction results indicated that 3 is protonated at proton-switchable binding sites in acidic conditions. Hence, facilitating binding of arsenate and dichromate is resulted from both electrostatic interactions and hydrogen bonding. To understand the selectivity of 3, the retention of dichromate anions in the presence of Cl{sup -}, NO{sub 3}{sup -}, and SO{sub 4}{sup 2-} anions at pH 1.5 was also examined. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Molecular Cloning and Expression of Bacterial Mercuric Reductase ...

African Journals Online (AJOL)

In order to characterize the bacterial mercuric reductase (merA) gene, mercury resistant (Hgr) Escherichia coli strains have been isolated from various mercury contaminated sites of India. Their minimum inhibitory concentration (MIC) for Hg and zone of inhibition for different antibiotics were measured, and finally mer operon ...

Molecular Cloning and Expression of Bacterial Mercuric Reductase ...

African Journals Online (AJOL)

USER

2010-06-21

Jun 21, 2010 ... In order to characterize the bacterial mercuric reductase (merA) gene, mercury resistant (Hgr). Escherichia coli strains have been isolated from various mercury contaminated sites of India. Their minimum inhibitory concentration (MIC) for Hg and zone of inhibition for different antibiotics were measured, and ...

Potency of a novel saw palmetto ethanol extract, SPET-085, for inhibition of 5alpha-reductase II.

Science.gov (United States)

Pais, Pilar

2010-08-01

The nicotinamide adenine dinucleotide phosphate (NADPH)-dependent membrane protein 5alpha-reductase irreversibly catalyses the conversion of testosterone to the most potent androgen, 5alpha-dihydrotestosterone (DHT). In humans, two 5alpha-reductase isoenyzmes are expressed: type I and type II. Type II is found primarily in prostate tissue. Saw palmetto extract (SPE) has been widely used for the treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia (BPH). The mechanisms of the pharmacological effects of SPE include the inhibition of 5alpha-reductase, among other actions. Clinical studies of SPE have been equivocal, with some showing significant results and others not. These inconsistent results may be due, in part, to varying bioactivities of the SPE used in the studies. The aim of the present study was to determine the in vitro potency of a novel saw palmetto ethanol extract (SPET-085), an inhibitor of the 5alpha-reductase isoenzyme type II, in a cell-free test system. On the basis of the enzymatic conversion of the substrate androstenedione to the 5alpha-reduced product 5alpha-androstanedione, the inhibitory potency was measured and compared to those of finasteride, an approved 5alpha-reductase inhibitor. SPET-085 concentration-dependently inhibited 5alpha-reductase type II in vitro (IC(50)=2.88+/-0.45 microg/mL). The approved 5alpha-reductase inhibitor, finasteride, tested as positive control, led to 61% inhibition of 5alpha-reductase type II. SPET-085 effectively inhibits the enzyme that has been linked to BPH, and the amount of extract required for activity is very low compared to data reported for other extracts. It can be concluded from data in the literature that SPET-085 is as effective as a hexane extract of saw palmetto that exhibited the highest levels of bioactivity, and is more effective than other SPEs tested. This study confirmed that SPET-085 has prostate health-promoting bioactivity that also corresponds favorably to

Intraethnic variation in steroid-5-alpha-reductase polymorphisms in ...

Indian Academy of Sciences (India)

2015-06-01

Jun 1, 2015 ... in prostate cancer patients: a potential factor implicated ... reductase alpha polypeptides 1 and 2 in a set of 601 prostate cancer patients from four ..... tion in the key androgen-regulating genes androgen receptor, cytochrome ...

Molecular and phenotypic characterization of transgenic soybean expressing the Arabidopsis ferric chelate reductase gene, FRO2.

Science.gov (United States)

Vasconcelos, Marta; Eckert, Helene; Arahana, Venancio; Graef, George; Grusak, Michael A; Clemente, Tom

2006-10-01

Soybean (Glycine max Merr.) production is reduced under iron-limiting calcareous soils throughout the upper Midwest regions of the US. Like other dicotyledonous plants, soybean responds to iron-limiting environments by induction of an active proton pump, a ferric iron reductase and an iron transporter. Here we demonstrate that heterologous expression of the Arabidopsis thaliana ferric chelate reductase gene, FRO2, in transgenic soybean significantly enhances Fe(+3) reduction in roots and leaves. Root ferric reductase activity was up to tenfold higher in transgenic plants and was not subjected to post-transcriptional regulation. In leaves, reductase activity was threefold higher in the transgenic plants when compared to control. The enhanced ferric reductase activity led to reduced chlorosis, increased chlorophyll concentration and a lessening in biomass loss in the transgenic events between Fe treatments as compared to control plants grown under hydroponics that mimicked Fe-sufficient and Fe-deficient soil environments. However, the data indicate that constitutive FRO2 expression under non-iron stress conditions may lead to a decrease in plant productivity as reflected by reduced biomass accumulation in the transgenic events under non-iron stress conditions. When grown at Fe(III)-EDDHA levels greater than 10 microM, iron concentration in the shoots of transgenic plants was significantly higher than control. The same observation was found in the roots in plants grown at iron levels higher than 32 microM Fe(III)-EDDHA. These results suggest that heterologous expression of an iron chelate reductase in soybean can provide a route to alleviate iron deficiency chlorosis.

Respiratory alkalosis

Science.gov (United States)

Alkalosis - respiratory ... leads to shortness of breath can also cause respiratory alkalosis (such as pulmonary embolism and asthma). ... Treatment is aimed at the condition that causes respiratory alkalosis. Breathing into a paper bag -- or using ...

Research progress on the roles of aldose reductase in diabetic retinopathy

Directory of Open Access Journals (Sweden)

Hong-Zhe Li

2015-07-01

Full Text Available Aldose reductase(ARbelonging to nicotinamide-adenine dinucleotide phosphate(NADPH-dependent aldehyde-keto reductase superfamily, is the key rate-limiting enzyme in the polyol pathway which plays an important role in the body's high-sugar metabolism. AR is widely present in the kidneys, blood vessels, lens, retina, heart, skeletal muscle and other tissues and organs, converts glucose to sorbitol which easy permeability of cell membranes, cause cell swelling, degeneration, necrosis, and have a close relationship with the development of chronic complications of diabetes mellitus. Diabetic retinopathy(DRis a multifactorial disease, the exact cause is currently unknown, but polyol pathway has been demonstrated to play an important role in the pathogenesis of DR. Clinical risk factors such as blood sugar control, blood pressure and other treatments for DR only play a part effect of remission or invalid, if we can find out DR genes associated with the disease, this will contribute to a better understanding of the pathological mechanisms and contribute to the development of new treatments and drugs. The current research progress of AR, AR gene polymorphism, Aldose reductase inhibitors to DR was reviewed in this article.

Inhibition of steroid 5 alpha-reductase by specific aliphatic unsaturated fatty acids.

Science.gov (United States)

Liang, T; Liao, S

1992-01-01

Human or rat microsomal 5 alpha-reductase activity, as measured by enzymic conversion of testosterone into 5 alpha-dihydrotestosterone or by binding of a competitive inhibitor, [3H]17 beta-NN-diethulcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one ([3H]4-MA) to the reductase, is inhibited by low concentrations (less than 10 microM) of certain polyunsaturated fatty acids. The relative inhibitory potencies of unsaturated fatty acids are, in decreasing order: gamma-linolenic acid greater than cis-4,7,10,13,16,19-docosahexaenoic acid = cis-6,9,12,15-octatetraenoic acid = arachidonic acid = alpha-linolenic acid greater than linoleic acid greater than palmitoleic acid greater than oleic acid greater than myristoleic acid. Other unsaturated fatty acids such as undecylenic acid, erucic acid and nervonic acid, are inactive. The methyl esters and alcohol analogues of these compounds, glycerols, phospholipids, saturated fatty acids, retinoids and carotenes were inactive even at 0.2 mM. The results of the binding assay and the enzymic assay correlated well except for elaidic acid and linolelaidic acid, the trans isomers of oleic acid and linoleic acid respectively, which were much less active than their cis isomers in the binding assay but were as potent in the enzymic assay. gamma-Linolenic acid had no effect on the activities of two other rat liver microsomal enzymes: NADH:menadione reductase and glucuronosyl transferase. gamma-Linolenic acid, the most potent inhibitor tested, decreased the Vmax. and increased Km values of substrates, NADPH and testosterone, and promoted dissociation of [3H]4-MA from the microsomal reductase. gamma-Linolenic acid, but not the corresponding saturated fatty acid (stearic acid), inhibited the 5 alpha-reductase activity, but not the 17 beta-dehydrogenase activity, of human prostate cancer cells in culture. These results suggest that unsaturated fatty acids may play an important role in regulating androgen action in target cells. PMID:1637346

Expression, purification, crystallization and preliminary X-ray analysis of perakine reductase, a new member of the aldo-keto reductase enzyme superfamily from higher plants

Science.gov (United States)

Rosenthal, Cindy; Mueller, Uwe; Panjikar, Santosh; Sun, Lianli; Ruppert, Martin; Zhao, Yu; Stöckigt, Joachim

2006-01-01

Perakine reductase (PR) is a novel member of the aldo-keto reductase enzyme superfamily from higher plants. PR from the plant Rauvolfia serpentina is involved in the biosynthesis of monoterpenoid indole alkaloids by performing NADPH-dependent reduction of perakine, yielding raucaffrinoline. However, PR can also reduce cinnamic aldehyde and some of its derivatives. After heterologous expression of a triple mutant of PR in Escherichia coli, crystals of the purified and methylated enzyme were obtained by the hanging-drop vapour-diffusion technique at 293 K with 100 mM sodium citrate pH 5.6 and 27% PEG 4000 as precipitant. Crystals belong to space group C2221 and diffract to 2.0 Å, with unit-cell parameters a = 58.9, b = 93.0, c = 143.4 Å. PMID:17142919

SORPTION OF ARSENATE AND ARSENITE ON RUO2 X H2O: ANALYSIS OF SORBED PHASE OXIDATION STATE BY XANES IN ADVANCED PHOTON SOURCE ACTIVITY REPORT 2002

Science.gov (United States)

The sorption reactions of arsenate (As(V)) and arsenite (As(III)) on RuO2 x H2O were examined by X-ray Absorption Near Edge Spectroscopy (XANES) to elucidate the solid state speciation of sorbed As. At all pH values studied (pH 4-8), RuO2 x H

The Nox/Ferric reductase/Ferric reductase-like families of Eumycetes.

Science.gov (United States)

Grissa, Ibtissem; Bidard, Frédérique; Grognet, Pierre; Grossetete, Sandrine; Silar, Philippe

2010-09-01

Reactive Oxygen Species (ROS) are involved in plant biomass degradation by fungi and development of fungal structures. While the ROS-generating NADPH oxidases from filamentous fungi are under strong scrutiny, much less is known about the related integral Membrane (or Ferric) Reductases (IMRs). Here, we present a survey of these enzymes in 29 fungal genomes covering the entire available range of fungal diversity. IMRs are present in all fungal genomes. They can be classified into at least 24 families, underscoring the high diversity of these enzymes. Some are differentially regulated during colony or fruiting body development, as well as by the nature of the carbon source of the growth medium. Importantly, functional characterization of IMRs has been made on proteins belonging to only two families, while nothing or very little is known about the proteins of the other 22 families. Copyright © 2010 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Crystallization and preliminary X-ray diffraction studies of ferredoxin reductase from Leptospira interrogans

International Nuclear Information System (INIS)

Nascimento, Alessandro S.; Ferrarezi, Thiago; Catalano-Dupuy, Daniela L.; Ceccarelli, Eduardo A.; Polikarpov, Igor

2006-01-01

Crystals adequate for X-ray diffraction analysis have been prepared from L. interrogans ferredoxin-NADP + reductase. Ferredoxin-NADP + reductase (FNR) is an FAD-containing enzyme that catalyzes electron transfer between NADP(H) and ferredoxin. Here, results are reported of the recombinant expression, purification and crystallization of FNR from Leptospira interrogans, a parasitic bacterium of animals and humans. The L. interrogans FNR crystals belong to a primitive monoclinic space group and diffract to 2.4 Å resolution at a synchrotron source

Crystallization and preliminary X-ray diffraction studies of ferredoxin reductase from Leptospira interrogans

Energy Technology Data Exchange (ETDEWEB)

Nascimento, Alessandro S.; Ferrarezi, Thiago [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador Saocarlense 400, São Carlos, SP, 13560-970 (Brazil); Catalano-Dupuy, Daniela L.; Ceccarelli, Eduardo A. [Facultad de Ciencias Bioquímicas y Farmacéuticas, Molecular Biology Division, Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario (Argentina); Polikarpov, Igor, E-mail: ipolikarpov@if.sc.usp.br [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador Saocarlense 400, São Carlos, SP, 13560-970 (Brazil)

2006-07-01

Crystals adequate for X-ray diffraction analysis have been prepared from L. interrogans ferredoxin-NADP{sup +} reductase. Ferredoxin-NADP{sup +} reductase (FNR) is an FAD-containing enzyme that catalyzes electron transfer between NADP(H) and ferredoxin. Here, results are reported of the recombinant expression, purification and crystallization of FNR from Leptospira interrogans, a parasitic bacterium of animals and humans. The L. interrogans FNR crystals belong to a primitive monoclinic space group and diffract to 2.4 Å resolution at a synchrotron source.

The Drosophila carbonyl reductase sniffer is an efficient 4-oxonon-2-enal (4ONE) reductase.

Science.gov (United States)

Martin, Hans-Jörg; Ziemba, Marta; Kisiela, Michael; Botella, José A; Schneuwly, Stephan; Maser, Edmund

2011-05-30

Studies with the fruit-fly Drosophila melanogaster demonstrated that the enzyme sniffer prevented oxidative stress-induced neurodegeneration. Mutant flies overexpressing sniffer had significantly extended life spans in a 99.5% oxygen atmosphere compared to wild-type flies. However, the molecular mechanism of this protection remained unclear. Sequence analysis and database searches identified sniffer as a member of the short-chain dehydrogenase/reductase superfamily with a 27.4% identity to the human enzyme carbonyl reductase type I (CBR1). As CBR1 catalyzes the reduction of the lipid peroxidation products 4HNE and 4ONE, we tested whether sniffer is able to metabolize these lipid derived aldehydes by carbonyl reduction. To produce recombinant enzyme, the coding sequence of sniffer was amplified from a cDNA-library, cloned into a bacterial expression vector and the His-tagged protein was purified by Ni-chelate chromatography. We found that sniffer catalyzed the NADPH-dependent carbonyl reduction of 4ONE (K(m)=24±2 μM, k(cat)=500±10 min(-1), k(cat)/K(m)=350 s(-1) mM(-1)) but not that of 4HNE. The reaction product of 4ONE reduction by sniffer was mainly 4HNE as shown by HPLC- and GC/MS analysis. Since 4HNE, though still a potent electrophile, is less neurotoxic and protein reactive than 4ONE, one mechanism by which sniffer exerts its neuroprotective effects in Drosophila after oxidative stress may be enzymatic reduction of 4ONE. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

[Comparison of Physico-chemical Aspects between E. coli and Human Dihydrofolate Reductase: an Equilibrium Unfolding Study].

Science.gov (United States)

Thapliyal, Charu; Jain, Neha; Chaudhuri, Pratima

2015-01-01

A protein, differing in origin, may exhibit variable physicochemical behaviour, difference in sequence homology, fold and function. Thus studying structure-function relationship of proteins from altered sources is meaningful in the sense that it may give rise to comparative aspects of their sequence-structure-function relationship. Dihydrofolate reductase is an enzyme involved in cell cycle regulation. It is a significant enzyme as.a target for developing anticancer drugs. Hence, detailed understanding of structure-function relationships of wide variants of the enzyme dihydrofolate reductase would be important for developing an inhibitor or an antagonist against the enzyme involved in the cellular developmental processes. In this communication, we have reported the comparative structure-function relationship between E. coli and human dihydrofolate reductase. The differences in the unfolding behaviour of these two proteins have been investigated to understand various properties of these two proteins like relative' stability differences and variation in conformational changes under identical denaturing conditions. The equilibrium unfolding mechanism of dihydrofolate reductase proteins using guanidine hydrochloride as a denaturant in the presence of various types of osmolytes has been monitored using loss in enzymatic activity, intrinsic tryptophan fluorescence and an extrinsic fluorophore 8-anilino-1-naphthalene-sulfonic acid as probes. It has been observed that osmolytes, such as 1M sucrose, and 30% glycerol, provided enhanced stability to both variants of dihydrofolate reductase. Their level of stabilisation has been observed to be dependent on intrinsic protein stability. It was observed that 100 mM proline does not show any 'significant stabilisation to either of dihydrofolate reductases. In the present study, it has been observed that the human protein is relatively less stable than the E.coli counterpart.

Crystallization of purple nitrous oxide reductase from Pseudomonas stutzeri

International Nuclear Information System (INIS)

Pomowski, Anja; Zumft, Walter G.; Kroneck, Peter M. H.; Einsle, Oliver

2010-01-01

The physiologically active form of nitrous oxide reductase was isolated and crystallized under strict exclusion of dioxygen and diffraction data were collected from crystals belonging to two different space groups. Nitrous oxide reductase (N 2 OR) from Pseudomonas stutzeri catalyzes the final step in denitrification: the two-electron reduction of nitrous oxide to molecular dinitrogen. Crystals of the enzyme were grown under strict exclusion of dioxygen by sitting-drop vapour diffusion using 2R,3R-butanediol as a cryoprotectant. N 2 OR crystallized in either space group P1 or P6 5 . Interestingly, the key determinant for the resulting space group was the crystallization temperature. Crystals belonging to space group P1 contained four 130 kDa dimers in the asymmetric unit, while crystals belonging to space group P6 5 contained a single dimer in the asymmetric unit. Diffraction data were collected to resolutions better than 2 Å

Respiratory

Science.gov (United States)

The words "respiratory" and "respiration" refer to the lungs and breathing. ... Boron WF. Organization of the respiratory system. In: Boron WF, Boulpaep EL, eds. Medical Physiology . 3rd ed. Philadelphia, PA: Elsevier; 2017:chap 26.

Purification and kinetic analysis of cytosolic and mitochondrial thioredoxin glutathione reductase extracted from Taenia solium cysticerci.

Science.gov (United States)

Plancarte, Agustin; Nava, Gabriela

2015-02-01

Thioredoxin glutathione reductases (TGRs) (EC 1.8.1.9) were purified to homogeneity from the cytosolic (cTsTGR) and mitochondrial (mTsTGR) fractions of Taenia solium, the agent responsible for neurocysticercosis, one of the major central nervous system parasitic diseases in humans. TsTGRs had a relative molecular weight of 132,000, while the corresponding value per subunit obtained under denaturing conditions, was of 62,000. Specific activities for thioredoxin reductase and glutathione reductase substrates for both TGRs explored were in the range or lower than values obtained for other platyhelminths and mammalian TGRs. cTsTGR and mTsTGR also showed hydroperoxide reductase activity using hydroperoxide as substrate. Km(DTNB) and Kcat(DTNB) values for cTsTGR and mTsTGR (88 µM and 1.9 s(-1); 45 µM and 12.6 s(-1), respectively) and Km(GSSG) and Kcat(GSSG) values for cTsTGR and mTsTGR (6.3 µM and 0.96 s(-1); 4 µM and 1.62 s(-1), respectively) were similar to or lower than those reported for mammalian TGRs. Mass spectrometry analysis showed that 12 peptides from cTsTGR and seven from mTsTGR were a match for gi|29825896 thioredoxin glutathione reductase [Echinococcus granulosus], confirming that both enzymes are TGRs. Both T. solium TGRs were inhibited by the gold compound auranofin, a selective inhibitor of thiol-dependent flavoreductases (I₅₀ = 3.25, 2.29 nM for DTNB and GSSG substrates, respectively for cTsTGR; I₅₀ = 5.6, 25.4 nM for mTsTGR toward the same substrates in the described order). Glutathione reductase activity of cTsTGR and mTsTGR exhibited hysteretic behavior with moderate to high concentrations of GSSG; this result was not observed either with thioredoxin, DTNB or NADPH. However, the observed hysteretic kinetics was suppressed with increasing amounts of both parasitic TGRs. These data suggest the existence of an effective substitute which may account for the lack of the detoxification enzymes glutathione reductase

The respiratory microbiome and respiratory infections

NARCIS (Netherlands)

Unger, Stefan A.; Bogaert, Debby

2017-01-01

Despite advances over the past ten years lower respiratory tract infections still comprise around a fifth of all deaths worldwide in children under five years of age with the majority in low- and middle-income countries. Known risk factors for severe respiratory infections and poor chronic

Brevetoxin (PbTx-2) influences the redox status and NPQ of Karenia brevis by way of thioredoxin reductase.

Science.gov (United States)

Chen, Wei; Colon, Ricardo; Louda, J William; Del Rey, Freddy Rodriguez; Durham, Michaella; Rein, Kathleen S

2018-01-01

The Florida red tide dinoflagellate, Karenia brevis, is the major harmful algal bloom dinoflagellate of the Gulf of Mexico and plays a destructive role in the region. Blooms of K. brevis can produce brevetoxins: ladder-shaped polyether (LSP) compounds, which can lead to adverse human health effects, such as reduced respiratory function through inhalation exposure, or neurotoxic shellfish poisoning through consumption of contaminated shellfish. The endogenous role of the brevetoxins remains uncertain. Recent work has shown that some forms of NADPH dependent thioredoxin reductase (NTR) are inhibited by brevetoxin-2 (PbTx-2). The study presented herein reveals that high toxin and low toxin K. brevis, which have a ten-fold difference in toxin content, also show a significant difference in their ability, not only to produce brevetoxin, but also in their cellular redox status and distribution of xanthophyll cycle pigments. These differences are likely due to the inhibition of NTR by brevetoxin. The work could shed light on the physiological role that brevetoxin fills for K. brevis. Copyright © 2017 Elsevier B.V. All rights reserved.

Is recurrent respiratory infection associated with allergic respiratory disease?

Science.gov (United States)

de Oliveira, Tiago Bittencourt; Klering, Everton Andrei; da Veiga, Ana Beatriz Gorini

2018-03-13

Respiratory infections cause high morbidity and mortality worldwide. This study aims to estimate the relationship between allergic respiratory diseases with the occurrence of recurrent respiratory infection (RRI) in children and adolescents. The International Study of Asthma and Allergies in Childhood questionnaire and a questionnaire that provides data on the history of respiratory infections and the use of antibiotics were used to obtain data from patients. The relationship between the presence of asthma or allergic rhinitis and the occurrence of respiratory infections in childhood was analyzed. We interviewed the caregivers of 531 children aged 0 to 15 years. The average age of participants was 7.43 years, with females accounting for 52.2%. This study found significant relationship between: presence of asthma or allergic rhinitis with RRI, with prevalence ratio (PR) of 2.47 (1.51-4.02) and 1.61 (1.34-1.93), respectively; respiratory allergies with use of antibiotics for respiratory problems, with PR of 5.32 (2.17-13.0) for asthma and of 1.64 (1.29-2.09) for allergic rhinitis; asthma and allergic rhinitis with diseases of the lower respiratory airways, with PR of 7.82 (4.63-13.21) and 1.65 (1.38-1.96), respectively. In contrast, no relationship between upper respiratory airway diseases and asthma and allergic rhinitis was observed, with PR of 0.71 (0.35-1.48) and 1.30 (0.87-1.95), respectively. RRI is associated with previous atopic diseases, and these conditions should be considered when treating children.

Role of aldose reductase C-106T polymorphism among diabetic Egyptian patients with different microvascular complications

Directory of Open Access Journals (Sweden)

Nermine Hossam Zakaria

2014-04-01

Full Text Available The aldose reductase pathway proves that elevated blood glucose promotes cellular dysfunction. The polyol pathway converts excess intracellular glucose into alcohols via activity of the aldose reductase. This enzyme catalyzes the conversion of glucose to sorbitol which triggers variety of intracellular changes in the tissues. Among diabetes, activity is drastically increased in association with three main consequences inside the cells. The aim of this study was to detect the association of the C-106 T polymorphism of the aldose reductase gene and its frequency among a sample of 150 Egyptian adults with type 2 diabetic patients having diabetic microvascular. The detection of the aldose reductase C-106 T polymorphism gene was done by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP. The genotype distribution of the C-106 T polymorphism showed that CC genotype was statistically significantly higher among patients with retinopathy compared to nephropathy. Patients with nephropathy had significant association with the TT genotype when compared with diabetic retinopathy patients. Follow up study after the genotype detection among recently diagnosed diabetic patients in order to give a prophylactic aldose reductase inhibitors; studying the microvascular complications and its relation to the genotype polymorphisms. The study may include multiple gene polymorphisms to make the relation between the gene and the occurrence of these complications more evident.

Nitrate reductase and nitrous oxide production by Fusarium oxysporum 11dn1 under aerobic and anaerobic conditions.

Science.gov (United States)

Kurakov, A V; Nosikov, A N; Skrynnikova, E V; L'vov, N P

2000-08-01

The fungus Fusarium oxysporum 11dn1 was found to be able to grow and produce nitrous oxide on nitrate-containing medium in anaerobic conditions. The rate of nitrous oxide formation was three to six orders of magnitude lower than the rates of molecular nitrogen production by common denitrifying bacteria. Acetylene and ammonia did not affect the release of nitrous oxide release. It was shown that under anaerobic conditions fast increase of nitrate reductase activity occurred, caused by the synthesis of enzyme de novo and protein dephosphorylation. Reverse transfer of the mycelium to aerobic conditions led to a decline in nitrate reductase activity and stopped nitrous oxide production. The presence of two nitrate reductases was shown, which differed in molecular mass, location, temperature optima, and activity in nitrate- and ammonium-containing media. Two enzymes represent assimilatory and dissimilatory nitrate reductases, which are active in aerobic and anaerobic conditions, respectively.

Impact of chromated copper arsenate (CCA) in wood mulch.

Science.gov (United States)

Townsend, Timothy G; Solo-Gabriele, Helena; Tolaymat, Thabet; Stook, Kristin

2003-06-20

The production of landscape mulch is a major market for the recycling of yard trash and waste wood. When wood recovered from construction and demolition (C&D) debris is used as mulch, it sometimes contains chromated copper arsenate (CCA)-treated wood. The presence of CCA-treated wood may cause some potential environmental problems as a result of the chromium, copper, and arsenic present. Research was performed to examine the leachability of the three metals from a variety of processed wood mixtures in Florida. The mixtures tested included mixed wood from C&D debris recycling facilities and mulch purchased from retail outlets. The synthetic precipitation leaching procedure (SPLP) was performed to examine the leaching of chromium, copper and arsenic. Results were compared to Florida's groundwater cleanup target levels (GWCTLs). Eighteen of the 22 samples collected from C&D debris processing facilities leached arsenic at concentrations greater than Florida's GWCTL of 50 microg/l. The mean leachable arsenic concentration for the C&D debris samples was 153 microg/l with a maximum of 558 microg/l. One of the colored mulch samples purchased from a retail outlet leached arsenic above 50 microg/l, while purchased mulch samples derived from virgin materials did not leach detectable arsenic (<5 microg/l). A mass balance approach was used to compute the potential metal concentrations (mg/kg) that would result from CCA-treated wood being present in wood mulch. Less than 0.1% CCA-treated wood would cause a mulch to exceed Florida's residential clean soil guideline for arsenic (0.8 mg/kg).

Transcriptional modulation of genes encoding nitrate reductase in ...

African Journals Online (AJOL)

The free aluminum (Al) content in soil can reach levels that are toxic to plants, and this has frequently limited increased productivity of cultures. Four genes encoding nitrate reductase (NR) were identified, named ZmNR1–4. With the aim of evaluating NR activity and the transcriptional modulation of the ZmNR1, ZmNR2, ...

Climate change and respiratory disease: European Respiratory Society position statement.

Science.gov (United States)

Ayres, J G; Forsberg, B; Annesi-Maesano, I; Dey, R; Ebi, K L; Helms, P J; Medina-Ramón, M; Windt, M; Forastiere, F

2009-08-01

Climate change will affect individuals with pre-existing respiratory disease, but the extent of the effect remains unclear. The present position statement was developed on behalf of the European Respiratory Society in order to identify areas of concern arising from climate change for individuals with respiratory disease, healthcare workers in the respiratory sector and policy makers. The statement was developed following a 2-day workshop held in Leuven (Belgium) in March 2008. Key areas of concern for the respiratory community arising from climate change are discussed and recommendations made to address gaps in knowledge. The most important recommendation was the development of more accurate predictive models for predicting the impact of climate change on respiratory health. Respiratory healthcare workers also have an advocatory role in persuading governments and the European Union to maintain awareness and appropriate actions with respect to climate change, and these areas are also discussed in the position statement.

DNA damage induction of ribonucleotide reductase.

OpenAIRE

Elledge, S J; Davis, R W

1989-01-01

RNR2 encodes the small subunit of ribonucleotide reductase, the enzyme that catalyzes the first step in the pathway for the production of deoxyribonucleotides needed for DNA synthesis. RNR2 is a member of a group of genes whose activities are cell cycle regulated and that are transcriptionally induced in response to the stress of DNA damage. An RNR2-lacZ fusion was used to further characterize the regulation of RNR2 and the pathway responsible for its response to DNA damage. beta-Galactosidas...

Cell death by SecTRAPs: thioredoxin reductase as a prooxidant killer of cells.

Directory of Open Access Journals (Sweden)

Karin Anestål

Full Text Available BACKGROUND: SecTRAPs (selenium compromised thioredoxin reductase-derived apoptotic proteins can be formed from the selenoprotein thioredoxin reductase (TrxR by targeting of its selenocysteine (Sec residue with electrophiles, or by its removal through C-terminal truncation. SecTRAPs are devoid of thioredoxin reductase activity but can induce rapid cell death in cultured cancer cell lines by a gain of function. PRINCIPAL FINDINGS: Both human and rat SecTRAPs killed human A549 and HeLa cells. The cell death displayed both apoptotic and necrotic features. It did not require novel protein synthesis nor did it show extensive nuclear fragmentation, but it was attenuated by use of caspase inhibitors. The redox active disulfide/dithiol motif in the N-terminal domain of TrxR had to be maintained for manifestation of SecTRAP cytotoxicity. Stopped-flow kinetics showed that NADPH can reduce the FAD moiety in SecTRAPs at similar rates as in native TrxR and purified SecTRAPs could maintain NADPH oxidase activity, which was accelerated by low molecular weight substrates such as juglone. In a cellular context, SecTRAPs triggered extensive formation of reactive oxygen species (ROS and consequently antioxidants could protect against the cell killing by SecTRAPs. CONCLUSIONS: We conclude that formation of SecTRAPs could contribute to the cytotoxicity seen upon exposure of cells to electrophilic agents targeting TrxR. SecTRAPs are prooxidant killers of cells, triggering mechanisms beyond those of a mere loss of thioredoxin reductase activity.

Crystallization and preliminary X-ray analysis of the NADPH-dependent 3-quinuclidinone reductase from Rhodotorula rubra

International Nuclear Information System (INIS)

Takeshita, Daijiro; Kataoka, Michihiko; Miyakawa, Takuya; Miyazono, Ken-ichi; Uzura, Atsuko; Nagata, Koji; Shimizu, Sakayu; Tanokura, Masaru

2009-01-01

The NADPH-dependent 3-quinuclidinone reductase from Rhodotorula rubra was expressed, purified, and crystallized and X-ray diffraction data of this crystal were collected to 2.2 Å resolution. (R)-3-Quinuclidinol is a useful compound that is applicable to the synthesis of various pharmaceuticals. The NADPH-dependent carbonyl reductase 3-quinuclidinone reductase from Rhodotorula rubra catalyzes the stereospecific reduction of 3-quinuclidinone to (R)-3-quinuclidinol and is expected to be utilized in industrial production of this alcohol. 3-Quinuclidinone reductase from R. rubra was expressed in Escherichia coli and purified using Ni-affinity and ion-exchange column chromatography. Crystals of the protein were obtained by the sitting-drop vapour-diffusion method using PEG 8000 as the precipitant. The crystals belonged to space group P4 1 2 1 2, with unit-cell parameters a = b = 91.3, c = 265.4 Å, and diffracted X-rays to 2.2 Å resolution. The asymmetric unit contained four molecules of the protein and the solvent content was 48.4%

Regulation of ribonucleotide reductase by Spd1 involves multiple mechanisms

DEFF Research Database (Denmark)

Nestoras, Konstantinos; Mohammed, Asma Hadi; Schreurs, Ann-Sofie

2010-01-01

The correct levels of deoxyribonucleotide triphosphates and their relative abundance are important to maintain genomic integrity. Ribonucleotide reductase (RNR) regulation is complex and multifaceted. RNR is regulated allosterically by two nucleotide-binding sites, by transcriptional control, and...

Partnering for optimal respiratory home care: physicians working with respiratory therapists to optimally meet respiratory home care needs.

Science.gov (United States)

Spratt, G; Petty, T L

2001-05-01

The need for respiratory care services continues to increase, reimbursement for those services has decreased, and cost-containment measures have increased the frequency of home health care. Respiratory therapists are well qualified to provide home respiratory care, reduce misallocation of respiratory services, assess patient respiratory status, identify problems and needs, evaluate the effect of the home setting, educate the patient on proper equipment use, monitor patient response to and complications of therapy, monitor equipment functioning, monitor for appropriate infection control procedures, make recommendations for changes to therapy regimen, and adjust therapy under the direction of the physician. Teamwork benefits all parties and offers cost and time savings, improved data collection and communication, higher job satisfaction, and better patient monitoring, education, and quality of life. Respiratory therapists are positioned to optimize treatment efficacy, maximize patient compliance, and minimize hospitalizations among patients receiving respiratory home care.

Relationship between nitrate reductase and nitrate uptake in phytoplankton in the Peru upwelling region

International Nuclear Information System (INIS)

Blasco, D.; MacIsaac, J.J.; Packard, T.T.; Dugdale, R.C.

1984-01-01

Nitrate reductase (NR) activity and 15 NO 3 - uptake in phytoplankton were compared under different environmental conditions on two cruises in the upwelling region off Peru. The NR activity and NO 3 - uptake rates responded differently to light and nutrients and the differences led to variations in the uptake: reductase ratio. Analysis of these variations suggests that the re-equilibration time of the two processes in response to environmental perturbation is an important source of variability. The nitrate uptake system responds faster than the nitrate reductase system. Considering these differences in response time the basic differences in the two processes, and the differences in their measurement, the authors conclude that the Nr activity measures the current nitrate-reducing potential, which reflects NO 3 - assimilation before the sampling time, while 15 NO 3 - uptake measures NO 3 - assimilation in the 6-h period following sampling

Cloning and characterization of a nitrite reductase gene related to ...

African Journals Online (AJOL)

STORAGESEVER

2010-03-01

Mar 1, 2010 ... Alexander et al., 2005) and heme-type nitrite reductase gene (Smith and ... owing to a genotype-dependent response (Zhang et al.,. 1991; Sakhanokho et al., ..... Improvement of cell culture conditions for rice. Jpn. Agric. Res.

Effect of ammonium and nitrate on ferric chelate reductase and nitrate reductase in Vaccinium species.

Science.gov (United States)

Poonnachit, U; Darnell, R

2004-04-01

Most Vaccinium species have strict soil requirements for optimal growth, requiring low pH, high iron availability and nitrogen primarily in the ammonium form. These soils are limited and are often located near wetlands. Vaccinium arboreum is a wild species adapted to a wide range of soils, including high pH, low iron, and nitrate-containing soils. This broader soil adaptation in V. arboreum may be related to increased efficiency of iron or nitrate uptake compared with the cultivated Vaccinium species. Nitrate, ammonium and iron uptake, and nitrate reductase (NR) and ferric chelate reductase (FCR) activities were compared in two Vaccinium species grown hydroponically in either nitrate or ammonia, with or without iron. The species studied were the wild V. arboreum and the cultivated V. corymbosum interspecific hybrid, which exhibits the strict soil requirements of most Vaccinium species. Ammonium uptake was significantly greater than nitrate uptake in both species, while nitrate uptake was greater in the wild species, V. arboreum, compared with the cultivated species, V. corymbosum. The increased nitrate uptake in V. arboreum was correlated with increased root NR activity compared with V. corymbosum. The lower nitrate uptake in V. corymbosum was reflected in decreased plant dry weight in this species compared with V. arboreum. Root FCR activity increased significantly in V. corymbosum grown under iron-deficient conditions, compared with the same species grown under iron-sufficient conditions or with V. arboreum grown under either iron condition. V. arboreum appears to be more efficient in acquiring nitrate compared with V. corymbosum, possibly due to increased NR activity and this may partially explain the wider soil adaptation of V. arboreum.

Expression, purification and molecular structure modeling of thioredoxin (Trx) and thioredoxin reductase (TrxR) from Acidithiobacillus ferrooxidans.

Science.gov (United States)

Wang, Yiping; Zhang, Xiaojian; Liu, Qing; Ai, Chenbing; Mo, Hongyu; Zeng, Jia

2009-07-01

The thioredoxin system consists of thioredoxin (Trx), thioredoxin reductase (TrxR) and NADPH, which plays several key roles in maintaining the redox environment of the cell. In Acidithiobacillus ferrooxidans, thioredoxin system may play important functions in the activity regulation of periplasmic proteins and energy metabolism. Here, we cloned thioredoxin (trx) and thioredoxin reductase (trxR) genes from Acidithiobacillus ferrooxidans, and expressed the genes in Escherichia coli. His-Trx and His-TrxR were purified to homogeneity with one-step Ni-NTA affinity column chromatography. Site-directed mutagenesis results confirmed that Cys33, Cys36 of thioredoxin, and Cys142, Cys145 of thioredoxin reductase were active-site residues.

The NADPH thioredoxin reductase C functions as an electron donor to 2-Cys peroxiredoxin in a thermophilic cyanobacterium Thermosynechococcus elongatus BP-1

International Nuclear Information System (INIS)

Sueoka, Keigo; Yamazaki, Teruaki; Hiyama, Tetsuo; Nakamoto, Hitoshi

2009-01-01

An NADPH thioredoxin reductase C was co-purified with a 2-Cys peroxiredoxin by the combination of anion exchange chromatography and electroelution from gel slices after native PAGE from a thermophilic cyanobacterium Thermosynechococcus elongatus as an NAD(P)H oxidase complex induced by oxidative stress. The result provided a strong evidence that the NADPH thioredoxin reductase C interacts with the 2-Cys peroxiredoxin in vivo. An in vitro reconstitution assay with purified recombinant proteins revealed that both proteins were essential for an NADPH-dependent reduction of H 2 O 2 . These results suggest that the reductase transfers the reducing power from NADPH to the peroxiredoxin, which reduces peroxides in the cyanobacterium under oxidative stress. In contrast with other NADPH thioredoxin reductases, the NADPH thioredoxin reductase C contains a thioredoxin-like domain in addition to an NADPH thioredoxin reductase domain in the same polypeptide. Each domain contains a conserved CXYC motif. A point mutation at the CXYC motif in the NADPH thioredoxin reductase domain resulted in loss of the NADPH oxidation activity, while a mutation at the CXYC motif in the thioredoxin-like domain did not affect the electron transfer, indicating that this motif is not essential in the electron transport from NADPH to the 2-Cys peroxiredoxin.

Alpha 1-blockers vs 5 alpha-reductase inhibitors in benign prostatic hyperplasia. A comparative review

DEFF Research Database (Denmark)

Andersen, J T

1995-01-01

During recent years, pharmacological treatment of symptomatic benign prostatic hyperplasia (BPH) has become the primary treatment choice for an increasing number of patients. The 2 principal drug classes employed are alpha 1-blockers and 5 alpha-reductase inhibitors. Current information from...... of patients who will respond well to alpha 1-blockers have yet to be identified, and data concerning the long term effects of these drugs are not yet available. 5 alpha-Reductase inhibitors have a slow onset of effect, but treatment leads to improvement in symptoms, reduction of the size of the prostate gland...... and improvement in objective parameters for bladder outflow obstruction. Approximately 30 to 50% of patients will respond to treatment with 5 alpha-reductase inhibitors. The definitive role of pharmacological treatment in symptomatic BPH remains to be established, although it seems that patients unfit...

Reconstitution of FMN-free NADPH-cytochrome P-450 reductase with a phosphorothioate analog of FMN: 31P NMR studies of the reconstituted protein

International Nuclear Information System (INIS)

Krum, D.P.; Otvos, J.D.; Calhoun, J.P.; Miziorko, H.M.; Masters, B.S.S.

1987-01-01

A phosphorothioate analog of FMN (FMNS) has been synthesized and shown to be completely competent in reconstituting the FMN-free form of NADPH-cytochrome P-450 reductase as evidenced by flavin determinations and cytochrome c reductase activity assays. The FMNS-reconstituted FMN-free reductase gives rise to an air-stable semiquinone, and the fluorescence of FMNS is quenched upon addition of FMN-free reductase. 31 P NMR spectra of the FMN-free reductase reveal only two resonances (-7.3 and -11.3 ppm), which are attributable to FAD. This result confirms the assignments of Otvos et al, and demonstrates unequivocally that there are no phosphate residues other than those of FMN and FAD attached to the steapsin-solubilized reductase. The addition of FMN to the FMN-free reductase resulted in the appearance of one additional resonance at 3.9 ppm. Addition of FMNS to the FMN-free reductase caused no change, surprisingly, in the 31 P NMR spectrum until Mn(II) was added, after which a peak centered at ∼ 45 ppm was observed. This unexpected result may be explained if the T 1 for the phosphate of FMNS is significantly longer than that of FMN, and suggests that the sulfur atom of FMNS may perturb the interaction of the phosphate with its protein environment. These results demonstrate the utility of phosphorothioate analogs as mechanistic probes for proteins containing nucleotide cofactors

Arsenic-contaminated soils. Genetically modified Pseudomonas spp. and their arsenic-phytoremediation potential

Energy Technology Data Exchange (ETDEWEB)

Sizova, O.I.; Kochetkov, V.V.; Validov, S.Z.; Boronin, A.M. [Inst. of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Moscow (Russian Federation); Kosterin, P.V.; Lyubun, Y.V. [Inst. of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov (Russian Federation)

2002-07-01

Sorghum was inoculated with Pseudomonas bacteria, including strains harboring an As-resistance plasmid, pBS3031, to enhance As-extraction by the plants. Pseudomonas strains (P. fluorescens 38a, P. putida 53a, and P. aureofaciens BS1393) were chosen because they are antagonistic to a wide range of phytopathogenic fungi and bacteria, and they can stimulate plant growth. The resistance of natural rhizospheric pseudomonads to sodium arsenite was assessed. Genetically modified Pseudomonas strains resistant to As(III)/As(V) were obtained via conjugation or transformation. The effects of the strains on the growth of sorghum on sodium-arsenite-containing soils were assessed. The conclusions from this study are: (1) It is possible to increase the survivability of sorghum growing in sodium-arsenite-containing soil by using rhizosphere pseudomonads. (2) The presence of pBS3031 offers the strains a certain selective advantage in arsenite-contaminated soil. (3) The presence of pBS3031 impairs plant growth, due to the As-resistance mechanism determined by this plasmid: the transformation of the less toxic arsenate into the more toxic, plant-root-available arsenite by arsenate reductase and the active removal of arsenite from bacterial cells. (4) Such a mechanism makes it possible to develop a bacteria-assisted phytoremediation technology for the cleanup of As-contaminated soils and is the only possible way of removing the soil-sorbed arsenates from the environment. (orig.)

Evaluation of the conserve flavin reductase gene from three ...

African Journals Online (AJOL)

STORAGESEVER

2009-12-15

Dec 15, 2009 ... means of PCR technique. The nucleic acid sequences of the PCR primers were designed using conserved nucleic acid sequences of the flavin reductase enzyme from. Rhodococcus sp. strain IGTS8. The oligonucleotide primers were as follows: 5'-GAA TTC ATG TCT GAC. AAG CCG AAT GCC-3' (forward) ...

Respiratory mechanics

CERN Document Server

Wilson, Theodore A

2016-01-01

This book thoroughly covers each subfield of respiratory mechanics: pulmonary mechanics, the respiratory pump, and flow. It presents the current understanding of the field and serves as a guide to the scientific literature from the golden age of respiratory mechanics, 1960 - 2010. Specific topics covered include the contributions of surface tension and tissue forces to lung recoil, the gravitational deformation of the lung, and the interdependence forces that act on pulmonary airways and blood vessels. The geometry and kinematics of the ribs is also covered in detail, as well as the respiratory action of the external and internal intercostal muscles, the mechanics of the diaphragm, and the quantitative compartmental models of the chest wall is also described. Additionally, flow in the airways is covered thoroughly, including the wave-speed and viscous expiratory flow-limiting mechanisms; convection, diffusion and the stationary front; and the distribution of ventilation. This is an ideal book for respiratory ...

Pyranopterin Coordination Controls Molybdenum Electrochemistry in Escherichia coli Nitrate Reductase.

Science.gov (United States)

Wu, Sheng-Yi; Rothery, Richard A; Weiner, Joel H

2015-10-09

We test the hypothesis that pyranopterin (PPT) coordination plays a critical role in defining molybdenum active site redox chemistry and reactivity in the mononuclear molybdoenzymes. The molybdenum atom of Escherichia coli nitrate reductase A (NarGHI) is coordinated by two PPT-dithiolene chelates that are defined as proximal and distal based on their proximity to a [4Fe-4S] cluster known as FS0. We examined variants of two sets of residues involved in PPT coordination: (i) those interacting directly or indirectly with the pyran oxygen of the bicyclic distal PPT (NarG-Ser(719), NarG-His(1163), and NarG-His(1184)); and (ii) those involved in bridging the two PPTs and stabilizing the oxidation state of the proximal PPT (NarG-His(1092) and NarG-His(1098)). A S719A variant has essentially no effect on the overall Mo(VI/IV) reduction potential, whereas the H1163A and H1184A variants elicit large effects (ΔEm values of -88 and -36 mV, respectively). Ala variants of His(1092) and His(1098) also elicit large ΔEm values of -143 and -101 mV, respectively. An Arg variant of His(1092) elicits a small ΔEm of +18 mV on the Mo(VI/IV) reduction potential. There is a linear correlation between the molybdenum Em value and both enzyme activity and the ability to support anaerobic respiratory growth on nitrate. These data support a non-innocent role for the PPT moieties in controlling active site metal redox chemistry and catalysis. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Pyranopterin Coordination Controls Molybdenum Electrochemistry in Escherichia coli Nitrate Reductase*

Science.gov (United States)

Wu, Sheng-Yi; Rothery, Richard A.; Weiner, Joel H.

2015-01-01

We test the hypothesis that pyranopterin (PPT) coordination plays a critical role in defining molybdenum active site redox chemistry and reactivity in the mononuclear molybdoenzymes. The molybdenum atom of Escherichia coli nitrate reductase A (NarGHI) is coordinated by two PPT-dithiolene chelates that are defined as proximal and distal based on their proximity to a [4Fe-4S] cluster known as FS0. We examined variants of two sets of residues involved in PPT coordination: (i) those interacting directly or indirectly with the pyran oxygen of the bicyclic distal PPT (NarG-Ser719, NarG-His1163, and NarG-His1184); and (ii) those involved in bridging the two PPTs and stabilizing the oxidation state of the proximal PPT (NarG-His1092 and NarG-His1098). A S719A variant has essentially no effect on the overall Mo(VI/IV) reduction potential, whereas the H1163A and H1184A variants elicit large effects (ΔEm values of −88 and −36 mV, respectively). Ala variants of His1092 and His1098 also elicit large ΔEm values of −143 and −101 mV, respectively. An Arg variant of His1092 elicits a small ΔEm of +18 mV on the Mo(VI/IV) reduction potential. There is a linear correlation between the molybdenum Em value and both enzyme activity and the ability to support anaerobic respiratory growth on nitrate. These data support a non-innocent role for the PPT moieties in controlling active site metal redox chemistry and catalysis. PMID:26297003

Respiratory signal analysis of liver cancer patients with respiratory-gated radiation therapy

International Nuclear Information System (INIS)

Kang, Dong Im; Jung, Sang Hoon; Kim, Chul Jong; Park, Hee Chul; Choi, Byung Ki

2015-01-01

External markers respiratory movement measuring device (RPM; Real-time Position Management, Varian Medical System, USA) Liver Cancer Radiation Therapy Respiratory gated with respiratory signal with irradiation time and the actual research by analyzing the respiratory phase with the breathing motion measurement device respiratory tuning evaluate the accuracy of radiation therapy May-September 2014 Novalis Tx. (Varian Medical System, USA) and liver cancer radiotherapy using respiratory gated RPM (Duty Cycle 20%, Gating window 40%-60%) of 16 patients who underwent total when recording the analyzed respiratory movement. After the breathing motion of the external markers recorded on the RPM was reconstructed by breathing through the acts phase analysis, for Beam-on Time and Duty Cycle recorded by using the reconstructed phase breathing breathing with RPM gated the prediction accuracy of the radiation treatment analysis and analyzed the correlation between prediction accuracy and Duty Cycle in accordance with the reproducibility of the respiratory movement. Treatment of 16 patients with respiratory cycle during the actual treatment plan was analyzed with an average difference -0.03 seconds (range -0.50 seconds to 0.09 seconds) could not be confirmed statistically significant difference between the two breathing (p = 0.472). The average respiratory period when treatment is 4.02 sec (0.71 sec), the average value of the respiratory cycle of the treatment was characterized by a standard deviation 7.43% (range 2.57 to 19.20%). Duty Cycle is that the actual average 16.05% (range 13.78 to 17.41%), average 56.05 got through the acts of the show and then analyzed% (range 39.23 to 75.10%) is planned in respiratory research phase (40% to 60%) in was confirmed. The investigation on the correlation between the ratio Duty Cycle and planned respiratory phase and the standard deviation of the respiratory cycle was analyzed in each -0.156 (p = 0.282) and -0.385 (p = 0.070). This study is

Comparing the xylose reductase/xylitol dehydrogenase and xylose isomerase pathways in arabinose and xylose fermenting Saccharomyces cerevisiae strains

Directory of Open Access Journals (Sweden)

Hahn-Hägerdal Bärbel

2008-10-01

Full Text Available Abstract Background Ethanolic fermentation of lignocellulosic biomass is a sustainable option for the production of bioethanol. This process would greatly benefit from recombinant Saccharomyces cerevisiae strains also able to ferment, besides the hexose sugar fraction, the pentose sugars, arabinose and xylose. Different pathways can be introduced in S. cerevisiae to provide arabinose and xylose utilisation. In this study, the bacterial arabinose isomerase pathway was combined with two different xylose utilisation pathways: the xylose reductase/xylitol dehydrogenase and xylose isomerase pathways, respectively, in genetically identical strains. The strains were compared with respect to aerobic growth in arabinose and xylose batch culture and in anaerobic batch fermentation of a mixture of glucose, arabinose and xylose. Results The specific aerobic arabinose growth rate was identical, 0.03 h-1, for the xylose reductase/xylitol dehydrogenase and xylose isomerase strain. The xylose reductase/xylitol dehydrogenase strain displayed higher aerobic growth rate on xylose, 0.14 h-1, and higher specific xylose consumption rate in anaerobic batch fermentation, 0.09 g (g cells-1 h-1 than the xylose isomerase strain, which only reached 0.03 h-1 and 0.02 g (g cells-1h-1, respectively. Whereas the xylose reductase/xylitol dehydrogenase strain produced higher ethanol yield on total sugars, 0.23 g g-1 compared with 0.18 g g-1 for the xylose isomerase strain, the xylose isomerase strain achieved higher ethanol yield on consumed sugars, 0.41 g g-1 compared with 0.32 g g-1 for the xylose reductase/xylitol dehydrogenase strain. Anaerobic fermentation of a mixture of glucose, arabinose and xylose resulted in higher final ethanol concentration, 14.7 g l-1 for the xylose reductase/xylitol dehydrogenase strain compared with 11.8 g l-1 for the xylose isomerase strain, and in higher specific ethanol productivity, 0.024 g (g cells-1 h-1 compared with 0.01 g (g cells-1 h-1

Incidence of respiratory viruses in Peruvian children with acute respiratory infections.

Science.gov (United States)

del Valle Mendoza, Juana; Cornejo-Tapia, Angela; Weilg, Pablo; Verne, Eduardo; Nazario-Fuertes, Ronald; Ugarte, Claudia; del Valle, Luis J; Pumarola, Tomás

2015-06-01

Acute respiratory infections are responsible for high morbi-mortality in Peruvian children. However, the etiological agents are poorly identified. This study, conducted during the pandemic outbreak of H1N1 influenza in 2009, aims to determine the main etiological agents responsible for acute respiratory infections in children from Lima, Peru. Nasopharyngeal swabs collected from 717 children with acute respiratory infections between January 2009 and December 2010 were analyzed by multiplex RT-PCR for 13 respiratory viruses: influenza A, B, and C virus; parainfluenza virus (PIV) 1, 2, 3, and 4; and human respiratory syncytial virus (RSV) A and B, among others. Samples were also tested with direct fluorescent-antibodies (DFA) for six respiratory viruses. RT-PCR and DFA detected respiratory viruses in 240 (33.5%) and 85 (11.9%) cases, respectively. The most common etiological agents were RSV-A (15.3%), followed by influenza A (4.6%), PIV-1 (3.6%), and PIV-2 (1.8%). The viruses identified by DFA corresponded to RSV (5.9%) and influenza A (1.8%). Therefore, respiratory syncytial viruses (RSV) were found to be the most common etiology of acute respiratory infections. The authors suggest that active surveillance be conducted to identify the causative agents and improve clinical management, especially in the context of possible circulation of pandemic viruses. © 2015 Wiley Periodicals, Inc.

Arsenate biotransformation by Microcystis aeruginosa under different nitrogen and phosphorus levels.

Science.gov (United States)

Che, Feifei; Du, Miaomiao; Yan, Changzhou

2018-04-01

The arsenate (As(V)) biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen (N) and phosphorus (P) has been studied under laboratory conditions. When 15μg/L As(V) was added, N and P in the medium showed effective regulation on arsenic (As) metabolism in M. aeruginosa, resulting in significant differences in the algal growth among different N and P treatments. Under 0.2mg/L P treatment, increases in N concentration (4-20mg/L) significantly stimulated the cell growth and therefore indirectly enhanced the production of dimethylarsinic acid (DMA), the main As metabolite, accounting for 71%-79% of the total As in the medium. Meanwhile, 10-20mg/L N treatments accelerated the ability of As metabolization by M. aeruginosa, leading to higher contents of DMA per cell. However, As(V) uptake by M. aeruginosa was significantly impeded by 0.5-1.0mg/L P treatment, resulting in smaller rates of As transformation in M. aeruginosa as well as lower contents of As metabolites in the medium. Our data demonstrated that As(V) transformation by M. aeruginosa was significantly accelerated by increasing N levels, while it was inhibited by increasing P levels. Overall, both P and N play key roles in As(V) biotransformation processes. Copyright © 2017. Published by Elsevier B.V.

The microbiota of the respiratory tract : Gatekeeper to respiratory health

NARCIS (Netherlands)

Man, Wing Ho; De Steenhuijsen Piters, Wouter A.A.; Bogaert, Debby

2017-01-01

The respiratory tract is a complex organ system that is responsible for the exchange of oxygen and carbon dioxide. The human respiratory tract spans from the nostrils to the lung alveoli and is inhabited by niche-specific communities of bacteria. The microbiota of the respiratory tract probably acts

Evolution of copper arsenate resistance for enhanced enargite bioleaching using the extreme thermoacidophile Metallosphaera sedula.

Science.gov (United States)

Ai, Chenbing; McCarthy, Samuel; Liang, Yuting; Rudrappa, Deepak; Qiu, Guanzhou; Blum, Paul

2017-12-01

Adaptive laboratory evolution (ALE) was employed to isolate arsenate and copper cross-resistant strains, from the copper-resistant M. sedula CuR1. The evolved strains, M. sedula ARS50-1 and M. sedula ARS50-2, contained 12 and 13 additional mutations, respectively, relative to M. sedula CuR1. Bioleaching capacity of a defined consortium (consisting of a naturally occurring strain and a genetically engineered copper sensitive strain) was increased by introduction of M. sedula ARS50-2, with 5.31 and 26.29% more copper recovered from enargite at a pulp density (PD) of 1 and 3% (w/v), respectively. M. sedula ARS50-2 arose as the predominant species and modulated the proportions of the other two strains after it had been introduced. Collectively, the higher Cu 2+ resistance trait of M. sedula ARS50-2 resulted in a modulated microbial community structure, and consolidating enargite bioleaching especially at elevated PD.

Respiratory Home Health Care

Science.gov (United States)

... Us Home > Healthy Living > Living With Lung Disease > Respiratory Home Health Care Font: Aerosol Delivery Oxygen Resources ... Teenagers Living With Lung Disease Articles written by Respiratory Experts Respiratory Home Health Care Respiratory care at ...

Identification and functional evaluation of the reductases and dehydrogenases from Saccharomyces cerevisiae involved in vanillin resistance.

Science.gov (United States)

Wang, Xinning; Liang, Zhenzhen; Hou, Jin; Bao, Xiaoming; Shen, Yu

2016-04-01

Vanillin, a type of phenolic released during the pre-treatment of lignocellulosic materials, is toxic to microorganisms and therefore its presence inhibits the fermentation. The vanillin can be reduced to vanillyl alcohol, which is much less toxic, by the ethanol producer Saccharomyces cerevisiae. The reducing capacity of S. cerevisiae and its vanillin resistance are strongly correlated. However, the specific enzymes and their contribution to the vanillin reduction are not extensively studied. In our previous work, an evolved vanillin-resistant strain showed an increased vanillin reduction capacity compared with its parent strain. The transcriptome analysis suggested the reductases and dehydrogenases of this vanillin resistant strain were up-regulated. Using this as a starting point, 11 significantly regulated reductases and dehydrogenases were selected in the present work for further study. The roles of these reductases and dehydrogenases in the vanillin tolerance and detoxification abilities of S. cerevisiae are described. Among the candidate genes, the overexpression of the alcohol dehydrogenase gene ADH6, acetaldehyde dehydrogenase gene ALD6, glucose-6-phosphate 1-dehydrogenase gene ZWF1, NADH-dependent aldehyde reductase gene YNL134C, and aldo-keto reductase gene YJR096W increased 177, 25, 6, 15, and 18 % of the strain μmax in the medium containing 1 g L(-1) vanillin. The in vitro detected vanillin reductase activities of strain overexpressing ADH6, YNL134C and YJR096W were notably higher than control. The vanillin specific reduction rate increased by 8 times in ADH6 overexpressed strain but not in YNL134C and YJR096W overexpressed strain. This suggested that the enzymes encoded by YNL134C and YJR096W might prefer other substrate and/or could not show their effects on vanillin on the high background of Adh6p in vivo. Overexpressing ALD6 and ZWF1 mainly increased the [NADPH]/[NADP(+)] and [GSH]/[GSSG] ratios but not the vanillin reductase activities. Their

Structural insights into the neuroprotective-acting carbonyl reductase Sniffer of Drosophila melanogaster.

Science.gov (United States)

Sgraja, Tanja; Ulschmid, Julia; Becker, Katja; Schneuwly, Stephan; Klebe, Gerhard; Reuter, Klaus; Heine, Andreas

2004-10-01

In vivo studies with the fruit-fly Drosophila melanogaster have shown that the Sniffer protein prevents age-dependent and oxidative stress-induced neurodegenerative processes. Sniffer is a NADPH-dependent carbonyl reductase belonging to the enzyme family of short-chain dehydrogenases/reductases (SDRs). The crystal structure of the homodimeric Sniffer protein from Drosophila melanogaster in complex with NADP+ has been determined by multiple-wavelength anomalous dispersion and refined to a resolution of 1.75 A. The observed fold represents a typical dinucleotide-binding domain as detected for other SDRs. With respect to the cofactor-binding site and the region referred to as substrate-binding loop, the Sniffer protein shows a striking similarity to the porcine carbonyl reductase (PTCR). This loop, in both Sniffer and PTCR, is substantially shortened compared to other SDRs. In most enzymes of the SDR family this loop adopts a well-defined conformation only after substrate binding and remains disordered in the absence of any bound ligands or even if only the dinucleotide cofactor is bound. In the structure of the Sniffer protein, however, the conformation of this loop is well defined, although no substrate is present. Molecular modeling studies provide an idea of how binding of substrate molecules to Sniffer could possibly occur.

Direct enzyme assay evidence confirms aldehyde reductase function of Ydr541cp and Ygl039wp from Saccharomyces cerevisiae

Science.gov (United States)

Aldehyde reductase gene ARI1 is a recently characterized member of intermediate subfamily under SDR (short-chain dehydrogenase/reductase) superfamily that revealed mechanisms of in situ detoxification of furfural and HMF for tolerance of Saccharomyces cerevisiae. Uncharacterized open reading frames ...

Regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and cholesterol biosynthesis by oxylanosterols

Energy Technology Data Exchange (ETDEWEB)

Panini, S.R.; Sexton, R.C.; Gupta, A.K.; Parish, E.J.; Chitrakorn, S.; Rudney, H.

1986-11-01

Treatment of rat intestinal epithelial cell cultures with the oxidosqualene cyclase inhibitor, 3 beta-(2-(diethylamino)-ethoxy)androst-5-en-17-one (U18666A), resulted in an accumulation of squalene 2,3:22,23-dioxide (SDO). When U18666A was withdrawn and the cells were treated with the sterol 14 alpha-demethylase inhibitor, ketoconazole, SDO was metabolized to a product identified as 24(S),25-epoxylanosterol. To test the biological effects and cellular metabolism of this compound, we prepared 24(RS),25-epoxylanosterol by chemical synthesis. The epimeric mixture of 24,25-epoxylanosterols could be resolved by high performance liquid chromatography on a wide-pore, non-endcapped, reverse phase column. Both epimers were effective suppressors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity of IEC-6 cells. The suppressive action of the natural epimer, 24(S),25-epoxylanosterol, but not that of 24(R),25-epoxylanosterol could be completely prevented by ketoconazole. IEC-6 cells could efficiently metabolize biosynthetic 24(S),25-epoxy(/sup 3/H)anosterol mainly to the known reductase-suppressor 24(S),25-epoxycholesterol. This metabolism was substantially reduced by ketoconazole. These data support the conclusion that 24(S),25-epoxylanosterol per se is not a suppressor of HMG-CoA reductase activity but is a precursor to a regulatory oxysterol(s). It has recently been reported that 25-hydroxycholesterol can occur naturally in cultured cells in amounts sufficient to effect regulation of HMG-CoA reductase. In order to investigate the biological effects of possible precursors of 25-hydroxycholesterol, we chemically synthesized 25-hydroxylanosterol and 25-hydroxylanostene-3-one. Both oxylanosterol derivatives suppressed cellular sterol synthesis at the level of HMG-CoA reductase. (Abstract Truncated)

Regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and cholesterol biosynthesis by oxylanosterols

International Nuclear Information System (INIS)

Panini, S.R.; Sexton, R.C.; Gupta, A.K.; Parish, E.J.; Chitrakorn, S.; Rudney, H.

1986-01-01

Treatment of rat intestinal epithelial cell cultures with the oxidosqualene cyclase inhibitor, 3 beta-[2-(diethylamino)-ethoxy]androst-5-en-17-one (U18666A), resulted in an accumulation of squalene 2,3:22,23-dioxide (SDO). When U18666A was withdrawn and the cells were treated with the sterol 14 alpha-demethylase inhibitor, ketoconazole, SDO was metabolized to a product identified as 24(S),25-epoxylanosterol. To test the biological effects and cellular metabolism of this compound, we prepared 24(RS),25-epoxylanosterol by chemical synthesis. The epimeric mixture of 24,25-epoxylanosterols could be resolved by high performance liquid chromatography on a wide-pore, non-endcapped, reverse phase column. Both epimers were effective suppressors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity of IEC-6 cells. The suppressive action of the natural epimer, 24(S),25-epoxylanosterol, but not that of 24(R),25-epoxylanosterol could be completely prevented by ketoconazole. IEC-6 cells could efficiently metabolize biosynthetic 24(S),25-epoxy[ 3 H]anosterol mainly to the known reductase-suppressor 24(S),25-epoxycholesterol. This metabolism was substantially reduced by ketoconazole. These data support the conclusion that 24(S),25-epoxylanosterol per se is not a suppressor of HMG-CoA reductase activity but is a precursor to a regulatory oxysterol(s). It has recently been reported that 25-hydroxycholesterol can occur naturally in cultured cells in amounts sufficient to effect regulation of HMG-CoA reductase. In order to investigate the biological effects of possible precursors of 25-hydroxycholesterol, we chemically synthesized 25-hydroxylanosterol and 25-hydroxylanostene-3-one. Both oxylanosterol derivatives suppressed cellular sterol synthesis at the level of HMG-CoA reductase. (Abstract Truncated)

Co-adsorption of Trichloroethylene and Arsenate by Iron-Impregnated Granular Activated Carbon.

Science.gov (United States)

Deng, Baolin; Kim, Eun-Sik

2016-05-01

Co-adsorption of trichloroethylene (TCE) and arsenate [As(V)] was investigated using modified granular activated carbons (GAC): untreated, sodium hypochlorite-treated (NaClO-GAC), and NaClO with iron-treated GAC (NaClO/Fe-GAC). Batch experiments of single- [TCE or As(V)] and binary- [TCE and As(V)] components solutions are evaluated through Langmuir and Freundlich isotherm models and adsorption kinetic tests. In the single-component system, the adsorption capacity of As(V) was increased by the NaClO-GAC and the NaClO/Fe-GAC. The untreated GAC showed a low adsorption capacity for As(V). Adsorption of TCE by the NaClO/Fe-GAC was maximized, with an increased Freundlich constant. Removal of TCE in the binary-component system was decreased 15% by the untreated GAC, and NaClO- and NaClO/Fe-GAC showed similar efficiency to the single-component system because of the different chemical status of the GAC surfaces. Results of the adsorption isotherms of As(V) in the binary-component system were similar to adsorption isotherms of the single-component system. The adsorption affinities of single- and binary-component systems corresponded with electron transfer, competitive adsorption, and physicochemical properties.

Ubiquinol-cytochrome c reductase (Complex III) electrochemistry at multi-walled carbon nanotubes/Nafion modified glassy carbon electrodes

International Nuclear Information System (INIS)

Pelster, Lindsey N.; Minteer, Shelley D.

2012-01-01

Highlights: ► The electron transport chain is important to the understanding of metabolism in the living cell. ► Ubiquinol-cytochrome c reductase is a membrane bound complex of the electron transport chain (Complex III). ► The paper details the first bioelectrochemical characterization of ubiquinol-cytochrome c reductase at an electrode. - Abstract: Electron transport chain complexes are critical to metabolism in living cells. Ubiquinol-cytochrome c reductase (Complex III) is responsible for carrying electrons from ubiquinol to cytochrome c, but the complex has not been evaluated electrochemically. This work details the bioelectrochemistry of ubiquinol-cytochrome c reductase of the electron transport chain of tuber mitochondria. The characterization of the electrochemistry of this enzyme is investigated in carboxylated multi-walled carbon nanotube/tetrabutyl ammonium bromide-modified Nafion ® modified glassy carbon electrodes by cyclic voltammetry. Increasing concentrations of cytochrome c result in a catalytic response from the active enzyme in the nanotube sandwich. The experiments show that the enzyme followed Michaelis–Menten kinetics with a K m for the immobilized enzyme of 2.97 (±0.11) × 10 −6 M and a V max of 6.31 (±0.82) × 10 −3 μmol min −1 at the electrode, but the K m and V max values decreased compared to the free enzyme in solution, which is expected for immobilized redox proteins. This is the first evidence of ubiquinol-cytochrome c reductase bioelectrocatalysis.

Preparation and certification of arsenate [As(V)] reference material, NMIJ CRM 7912-a.

Science.gov (United States)

Narukawa, Tomohiro; Kuroiwa, Takayoshi; Narushima, Izumi; Jimbo, Yasujiro; Suzuki, Toshihiro; Chiba, Koichi

2010-05-01

Arsenate [As(V)] solution reference material, National Metrology Institute of Japan (NMIJ) certified reference material (CRM) 7912-a, for speciation of arsenic species was developed and certified by NMIJ, the National Institute of Advanced Industrial Science and Technology. High-purity As(2)O(3) reagent powder was dissolved in 0.8 M HNO(3) solution and As(III) was oxidized to As(V) with HNO(3) to prepare 100 mg kg(-1) of As(V) candidate CRM solution. The solution was bottled in 400 bottles (50 mL each). The concentration of As(V) was determined by four independent analytical techniques-inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectrometry, graphite furnace atomic absorption spectrometry, and liquid chromatography inductively coupled plasma mass spectrometry-according to As(V) calibration solutions, which were prepared from the arsenic standard of the Japan Calibration Service system and whose species was guaranteed to be As(V) by NMIJ. The uncertainties of all the measurements and preparation procedures were evaluated. The certified value of As(V) in the CRM is (99.53 +/- 1.67) mg kg(-1) (k = 2).

Isolation and expression of the Pneumocystis carinii dihydrofolate reductase gene

DEFF Research Database (Denmark)

Edman, J C; Edman, U; Cao, Mi-Mi

1989-01-01

Pneumocystis carinii dihydrofolate reductase (DHFR; 5,6,7,8-tetrahydrofolate: NADP+ oxidoreductase, EC 1.5.1.3) cDNA sequences have been isolated by their ability to confer trimethoprim resistance to Escherichia coli. Consistent with the recent conclusion that P. carinii is a member of the Fungi...

The 1-hydroxy-2-methyl-butenyl 4-diphosphate reductase gene from ...

African Journals Online (AJOL)

The 1-hydroxy-2-methyl-butenyl 4-diphosphate reductase gene from Taxus media: Cloning, characterization and functional identification. Y Sun, M Chen, J Tang, W Liu, C Yang, Y Yang, X Lan, M Hsieh, Z Liao ...

Comparative study on liquefaction of creosote and chromated copper arsenate (CCA)-treated wood and untreated southern pine wood: effects of acid catalyst content, liquefaction time, temperature, and phenol to wood ratio

Science.gov (United States)

Hui Pan; Chung-Yun Hse; Todd F. Shupe

2009-01-01

Creosote- and chromated copper arsenate (CCA)-treated wood waste and untreated southern pine wood were liquefied with phenol and sulfuric acid. The effects of sulfuric acid content, liquefaction time, liquefaction temperature, and phenol to wood ratio on liquefaction rate (i.e., wood residue content) were investigated and analyzed by analysis of variance (...

Atomic Structure of Salutaridine Reductase from the Opium Poppy (Papaver somniferum)

Energy Technology Data Exchange (ETDEWEB)

Higashi, Yasuhiro; Kutchan, Toni M.; Smith, Thomas J. (Danforth)

2011-11-18

The opium poppy (Papaver somniferum L.) is one of the oldest known medicinal plants. In the biosynthetic pathway for morphine and codeine, salutaridine is reduced to salutaridinol by salutaridine reductase (SalR; EC 1.1.1.248) using NADPH as coenzyme. Here, we report the atomic structure of SalR to a resolution of {approx}1.9 {angstrom} in the presence of NADPH. The core structure is highly homologous to other members of the short chain dehydrogenase/reductase family. The major difference is that the nicotinamide moiety and the substrate-binding pocket are covered by a loop (residues 265-279), on top of which lies a large 'flap'-like domain (residues 105-140). This configuration appears to be a combination of the two common structural themes found in other members of the short chain dehydrogenase/reductase family. Previous modeling studies suggested that substrate inhibition is due to mutually exclusive productive and nonproductive modes of substrate binding in the active site. This model was tested via site-directed mutagenesis, and a number of these mutations abrogated substrate inhibition. However, the atomic structure of SalR shows that these mutated residues are instead distributed over a wide area of the enzyme, and many are not in the active site. To explain how residues distal to the active site might affect catalysis, a model is presented whereby SalR may undergo significant conformational changes during catalytic turnover.

Respiratory Failure

Science.gov (United States)

Respiratory failure happens when not enough oxygen passes from your lungs into your blood. Your body's organs, ... brain, need oxygen-rich blood to work well. Respiratory failure also can happen if your lungs can' ...

Respiratory system

Science.gov (United States)

Bartlett, R. G., Jr.

1973-01-01

The general anatomy and function of the human respiratory system is summarized. Breathing movements, control of breathing, lung volumes and capacities, mechanical relations, and factors relevant to respiratory support and equipment design are discussed.

Relationship between nitrate reductase and nitrate uptake in phytoplankton in the Peru upwelling region

International Nuclear Information System (INIS)

Blasco, D.; MacIsaac, J.J.; Packard, T.T.; Dugdale, R.C.

1984-01-01

Nitrate reductase (NR) activity and 15 NO 3 - uptake in phytoplankton were compared under different environmental conditions on two cruises in the upwelling region off Peru. The NR activity and NO 3 - uptake rates responded differently to light and nutrients and the differences led to variations in the uptake:reductase ratio. Analysis of these variations suggests that the re-equilibration time of the two processes in response to environmental perturbation is an important source of variability. The nitrate uptake system responds faster than the nitrate reductase system. Considering these differences in response time, the basic differences in the two processes, and the differences in their measurement, the authors conclude that the NR activity measures the current nitrate-reducing potential, which relfects NO 3 - assimilation before the sampling time, while 15 NO 3 - uptake measures NO 3 - assimilation in the 6-h period following sampling. Thus, considering the sampling time as a point of reference, the former is a measure of the past and the latter is a measure of the future

Removal of toxic ions (chromate, arsenate, and perchlorate) using reverse osmosis, nanofiltration, and ultrafiltration membranes

KAUST Repository

Yoon, Jaekyung

2009-09-01

Rejection characteristics of chromate, arsenate, and perchlorate were examined for one reverse osmosis (RO, LFC-1), two nanofiltration (NF, ESNA, and MX07), and one ultrafiltration (UF and GM) membranes that are commercially available. A bench-scale cross-flow flat-sheet filtration system was employed to determine the toxic ion rejection and the membrane flux. Both model and natural waters were used to prepare chromate, arsenate, and perchlorate solutions (approximately 100 μg L-1 for each anion) in mixtures in the presence of other salts (KCl, K2SO4, and CaCl2); and at varying pH conditions (4, 6, 8, and 10) and solution conductivities (30, 60, and 115 mS m-1). The rejection of target ions by the membranes increases with increasing solution pH due to the increasingly negative membrane charge with synthetic model waters. Cr(VI), As(V), and ClO4 - rejection follows the order LFC-1 (>90%) > MX07 (25-95%) ≅ ESNA (30-90%) > GM (3-47%) at all pH conditions. In contrast, the rejection of target ions by the membranes decreases with increasing solution conductivity due to the decreasingly negative membrane charge. Cr(VI), As(V), and ClO4 - rejection follows the order CaCl2 < KCl ≅ K2SO4 at constant pH and conductivity conditions for the NF and UF membranes tested. For natural waters the LFC-1 RO membrane with a small pore size (0.34 nm) had a significantly greater rejection for those target anions (>90%) excluding NO3 - (71-74%) than the ESNA NF membrane (11-56%) with a relatively large pore size (0.44 nm), indicating that size exclusion is at least partially responsible for the rejection. The ratio of solute radius (ri,s) to effective membrane pore radius (rp) was employed to compare ion rejection. For all of the ions, the rejection is higher than 70% when the ri,s/rp ratio is greater than 0.4 for the LFC-1 membrane, while for di-valent ions (CrO4 2 -, SO4 2 -, and HAsSO4 2 -) the rejection (38-56%) is fairly proportional to the ri,s/rp ratio (0.32-0.62) for the ESNA

Lactococcus lactis Thioredoxin Reductase Is Sensitive to Light Inactivation

DEFF Research Database (Denmark)

Björnberg, Olof; Viennet, Thibault; Skjoldager, Nicklas

2015-01-01

Thioredoxin, involved in numerous redox pathways, is maintained in the dithiol state by the nicotinamide adenine dinucleotide phosphate-dependent flavoprotein thioredoxin reductase (TrxR). Here, TrxR from Lactococcus lactis is compared with the well-characterized TrxR from Escherichia coli. The two...... enzymes belong to the same class of low-molecular weight thioredoxin reductases and display similar kcat values (∼25 s-1) with their cognate thioredoxin. Remarkably, however, the L. lactis enzyme is inactivated by visible light and furthermore reduces molecular oxygen 10 times faster than E. coli Trx......-resolution mass spectrometric analysis of heat-extracted FAD from light-damaged TrxR revealed a mass increment of 13.979 Da, relative to that of unmodified FAD, corresponding to the addition of one oxygen atom and the loss of two hydrogen atoms. Tandem mass spectrometry confined the increase in mass...

Novel bacterial sulfur oxygenase reductases from bioreactors treating gold-bearing concentrates

DEFF Research Database (Denmark)

Chen, Z-W; Liu, Y-Y; Wu, J-F

2007-01-01

The microbial community and sulfur oxygenase reductases of metagenomic DNA from bioreactors treating gold-bearing concentrates were studied by 16S rRNA library, real-time polymerase chain reaction (RT-PCR), conventional cultivation, and molecular cloning. Results indicated that major bacterial......) of bacteria and archaea were 4.59 x 10(9) and 6.68 x 10(5), respectively. Bacterial strains representing Acidithiobacillus, Leptospirillum, and Sulfobacillus were isolated from the bioreactors. To study sulfur oxidation in the reactors, pairs of new PCR primers were designed for the detection of sulfur...... oxygenase reductase (SOR) genes. Three sor-like genes, namely, sor (Fx), sor (SA), and sor (SB) were identified from metagenomic DNAs of the bioreactors. The sor (Fx) is an inactivated SOR gene and is identical to the pseudo-SOR gene of Ferroplasma acidarmanus. The sor (SA) and sor (SB) showed...

Synthesis and Activity of a New Series of(Z-3-Phenyl-2-benzoylpropenoic Acid Derivatives as Aldose Reductase Inhibitors

Directory of Open Access Journals (Sweden)

Shao-Jie Wang

2007-04-01

Full Text Available During the course of studies directed towards the discovery of novel aldose reductase inhibitors for the treatment of diabetic complications, we synthesized a series of new (Z-3-phenyl-2-benzoylpropenoic acid derivatives and tested their in vitro inhibitory activities on rat lens aldose reductase. Of these compounds, (Z-3-(3,4-dihydroxyphenyl-2-(4-methylbenzoylpropenoicacid(3k was identified as the most potent inhibitor, with an IC50 of 0.49μM. The theoretical binding mode of 3k was obtained by simulation of its docking into the active site of the human aldose reductase crystal structure.

Influence of rete testis fluid deprivation on the kinetic parameters of goat epididymal 5 alpha-reductase.

Science.gov (United States)

Kelce, W R; Lubis, A M; Braun, W F; Youngquist, R S; Ganjam, V K

1990-01-01

A surgical technique to cannulate the rete testis of the goat was utilized to examine the effects of rete testis fluid (RTF) deprivation on the enzymatic activity of epididymal 5 alpha-reductase. Kinetic techniques were used to determine whether the regional enzymatic effect of RTF deprivation is to decrease the apparent number of 5 alpha-reductase active sites or the catalytic activity of each active site within the epididymal epithelium. Paired comparisons of (Vmax)app and (Km)app values between control and RTF-deprived epididymides indicated that RTF deprivation affected the value of (Vmax)app with no apparent change in the values of (Km)app in caput, corpus, and cauda epididymal regions. We conclude that RTF deprivation in the goat epididymis for 7 days results in a decreased number of apparent 5 alpha-reductase active sites within the epididymal epithelium.

Crystallization and preliminary X-ray analysis of the NADPH-dependent 3-quinuclidinone reductase from Rhodotorula rubra

Science.gov (United States)

Takeshita, Daijiro; Kataoka, Michihiko; Miyakawa, Takuya; Miyazono, Ken-ichi; Uzura, Atsuko; Nagata, Koji; Shimizu, Sakayu; Tanokura, Masaru

2009-01-01

(R)-3-Quinuclidinol is a useful compound that is applicable to the synthesis of various pharmaceuticals. The NADPH-dependent carbonyl reductase 3-­quinuclidinone reductase from Rhodotorula rubra catalyzes the stereospecific reduction of 3-quinuclidinone to (R)-3-quinuclidinol and is expected to be utilized in industrial production of this alcohol. 3-Quinuclidinone reductase from R. rubra was expressed in Escherichia coli and purified using Ni-affinity and ion-exchange column chromatography. Crystals of the protein were obtained by the sitting-drop vapour-diffusion method using PEG 8000 as the precipitant. The crystals belonged to space group P41212, with unit-cell parameters a = b = 91.3, c = 265.4 Å, and diffracted X-rays to 2.2 Å resolution. The asymmetric unit contained four molecules of the protein and the solvent content was 48.4%. PMID:19478454

Ferric reductase genes involved in high-affinity iron uptake are differentially regulated in yeast and hyphae of Candida albicans.

Science.gov (United States)

Jeeves, Rose E; Mason, Robert P; Woodacre, Alexandra; Cashmore, Annette M

2011-09-01

The pathogenic yeast Candida albicans possesses a reductive iron uptake system which is active in iron-restricted conditions. The sequestration of iron by this mechanism initially requires the reduction of free iron to the soluble ferrous form, which is catalysed by ferric reductase proteins. Reduced iron is then taken up into the cell by a complex of a multicopper oxidase protein and an iron transport protein. Multicopper oxidase proteins require copper to function and so reductive iron and copper uptake are inextricably linked. It has previously been established that Fre10 is the major cell surface ferric reductase in C. albicans and that transcription of FRE10 is regulated in response to iron levels. We demonstrate here that Fre10 is also a cupric reductase and that Fre7 also makes a significant contribution to cell surface ferric and cupric reductase activity. It is also shown, for the first time, that transcription of FRE10 and FRE7 is lower in hyphae compared to yeast and that this leads to a corresponding decrease in cell surface ferric, but not cupric, reductase activity. This demonstrates that the regulation of two virulence determinants, the reductive iron uptake system and the morphological form of C. albicans, are linked. Copyright © 2011 John Wiley & Sons, Ltd.

Intramolecular electron transfer in Pseudomonas aeruginosa cd(1) nitrite reductase

DEFF Research Database (Denmark)

Farver, Ole; Brunori, Maurizio; Cutruzzolà, Francesca

2009-01-01

) as the level of reduction increased in both the WT and the His mutant. Equilibrium standard enthalpy and entropy changes and activation parameters of this ET process were determined. We concluded that negative cooperativity is a common feature among the cd(1) nitrite reductases, and we discuss this control...

Respiratory Viruses in Febrile Neutropenic Patients with Respiratory Symptoms

Directory of Open Access Journals (Sweden)

Mohsen Meidani

2018-01-01

Full Text Available Background: Respiratory infections are a frequent cause of fever in neutropenic patients, whereas respiratory viral infections are not frequently considered as a diagnosis, which causes high morbidity and mortality in these patients. Materials and Methods: This prospective study was performed on 36 patients with neutropenia who admitted to hospital were eligible for inclusion with fever (single temperature of >38.3°C or a sustained temperature of >38°C for more than 1 h, upper and lower respiratory symptoms. Sampling was performed from the throat of the patient by the sterile swab. All materials were analyzed by quantitative real-time multiplex polymerase chain reaction covering the following viruses; influenza, parainfluenza virus (PIV, rhinovirus (RV, human metapneumovirus, and respiratory syncytial virus (RSV. Results: RV was the most frequently detected virus and then RSV was the most. PIV was not present in any of the tested samples. Furthermore, no substantial differences in the distribution of specific viral species were observed based on age, sex, neutropenia duration, hematological disorder, and respiratory tract symptoms and signs (P > 0.05. Conclusion: Our prospective study supports the hypothesis that respiratory viruses play an important role in the development of neutropenic fever, and thus has the potential to individualize infection treatment and to reduce the extensive use of antibiotics in immunocompromised patients with neutropenia.

Middle East Respiratory Syndrome

Centers for Disease Control (CDC) Podcasts

2014-07-07

This podcast discusses Middle East Respiratory Syndrome, or MERS, a viral respiratory illness caused by Middle East Respiratory Syndrome Coronavirus—MERS-CoV.  Created: 7/7/2014 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 7/7/2014.

Identification of a Novel Epoxyqueuosine Reductase Family by Comparative Genomics.

Science.gov (United States)

Zallot, Rémi; Ross, Robert; Chen, Wei-Hung; Bruner, Steven D; Limbach, Patrick A; de Crécy-Lagard, Valérie

2017-03-17

The reduction of epoxyqueuosine (oQ) is the last step in the synthesis of the tRNA modification queuosine (Q). While the epoxyqueuosine reductase (EC 1.17.99.6) enzymatic activity was first described 30 years ago, the encoding gene queG was only identified in Escherichia coli in 2011. Interestingly, queG is absent from a large number of sequenced genomes that harbor Q synthesis or salvage genes, suggesting the existence of an alternative epoxyqueuosine reductase in these organisms. By analyzing phylogenetic distributions, physical gene clustering, and fusions, members of the Domain of Unknown Function 208 (DUF208) family were predicted to encode for an alternative epoxyqueuosine reductase. This prediction was validated with genetic methods. The Q modification is present in Lactobacillus salivarius, an organism missing queG but harboring the duf208 gene. Acinetobacter baylyi ADP1 is one of the few organisms that harbor both QueG and DUF208, and deletion of both corresponding genes was required to observe the absence of Q and the accumulation of oQ in tRNA. Finally, the conversion oQ to Q was restored in an E. coli queG mutant by complementation with plasmids harboring duf208 genes from different bacteria. Members of the DUF208 family are not homologous to QueG enzymes, and thus, duf208 is a non-orthologous replacement of queG. We propose to name DUF208 encoding genes as queH. While QueH contains conserved cysteines that could be involved in the coordination of a Fe/S center in a similar fashion to what has been identified in QueG, no cobalamin was identified associated with recombinant QueH protein.

Nitrate reductase activity of Staphylococcus carnosus affecting the color formation in cured raw ham.

Science.gov (United States)

Bosse Née Danz, Ramona; Gibis, Monika; Schmidt, Herbert; Weiss, Jochen

2016-07-01

The influence of the nitrate reductase activity of two Staphylococcus carnosus strains used as starter cultures on the formation of nitrate, nitrite and color pigments in cured raw ham was investigated. In this context, microbiological, chemical and multivariate image analyses were carried out on cured raw hams, which were injected with different brines containing either nitrite or nitrate, with or without the S. carnosus starter cultures. During processing and storage, the viable counts of staphylococci remained constant at 6.5logcfu/g in the hams inoculated with starter cultures, while the background microbiota of the hams processed without the starter cultures developed after 14days. Those cured hams inoculated with S. carnosus LTH 7036 (high nitrate reductase activity) showed the highest decrease in nitrate and high nitrite concentrations in the end product, but were still in the range of the legal European level. The hams cured with nitrate and without starter culture or with the other strain, S. carnosus LTH 3838 (low nitrate reductase activity) showed higher residual nitrate levels and a lower nitrite content in the end product. The multivariate image analysis identified spatial and temporal differences in the meat pigment profiles of the differently cured hams. The cured hams inoculated with S. carnosus LTH 3838 showed an uncured core due to a delay in pigment formation. Therefore, the selection of starter cultures based on their nitrate reductase activity is a key point in the formation of curing compounds and color pigments in cured raw ham manufacture. Copyright © 2016 Elsevier Ltd. All rights reserved.

NADPH-Thioredoxin Reductase C Mediates the Response to Oxidative Stress and Thermotolerance in the Cyanobacterium Anabaena sp PCC7120

NARCIS (Netherlands)

Sanchez-Riego, Ana M.; Mata-Cabana, Alejandro; Galmozzi, CarlaV.; Florencio, Francisco J.

2016-01-01

NADPH-thioredoxin reductase C (NTRC) is a bimodular enzyme composed of an NADPH-thioredoxin reductase and a thiioredoxin domain extension in the same protein. In plants, NTRC has been described to be involved in the protection of the chloroplast against oxidative stress damage through reduction of

Sterol-induced Dislocation of 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase from Endoplasmic Reticulum Membranes into the Cytosol through a Subcellular Compartment Resembling Lipid Droplets*

Science.gov (United States)

Hartman, Isamu Z.; Liu, Pingsheng; Zehmer, John K.; Luby-Phelps, Katherine; Jo, Youngah; Anderson, Richard G. W.; DeBose-Boyd, Russell A.

2010-01-01

Sterol-induced binding to Insigs in the endoplasmic reticulum (ER) allows for ubiquitination of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme in cholesterol synthesis. This ubiquitination marks reductase for recognition by the ATPase VCP/p97, which mediates extraction and delivery of reductase from ER membranes to cytosolic 26 S proteasomes for degradation. Here, we report that reductase becomes dislocated from ER membranes into the cytosol of sterol-treated cells. This dislocation exhibits an absolute requirement for the actions of Insigs and VCP/p97. Reductase also appears in a buoyant fraction of sterol-treated cells that co-purifies with lipid droplets, cytosolic organelles traditionally regarded as storage depots for neutral lipids such as triglycerides and cholesteryl esters. Genetic, biochemical, and localization studies suggest a model in which reductase is dislodged into the cytosol from an ER subdomain closely associated with lipid droplets. PMID:20406816

Human herpesviruses respiratory infections in patients with acute respiratory distress (ARDS).

Science.gov (United States)

Bonizzoli, Manuela; Arvia, Rosaria; di Valvasone, Simona; Liotta, Francesco; Zakrzewska, Krystyna; Azzi, Alberta; Peris, Adriano

2016-08-01

Acute respiratory distress syndrome (ARDS) is today a leading cause of hospitalization in intensive care unit (ICU). ARDS and pneumonia are closely related to critically ill patients; however, the etiologic agent is not always identified. The presence of human herpes simplex virus 1, human cytomegalovirus and Epstein-Barr virus in respiratory samples of critically ill patients is increasingly reported even without canonical immunosuppression. The main aim of this study was to better understand the significance of herpesviruses finding in lower respiratory tract of ARDS patients hospitalized in ICU. The presence of this group of herpesviruses, in addition to the research of influenza viruses and other common respiratory viruses, was investigated in respiratory samples from 54 patients hospitalized in ICU, without a known microbiological causative agent. Moreover, the immunophenotype of each patient was analyzed. Herpesviruses DNA presence in the lower respiratory tract seemed not attributable to an impaired immunophenotype, whereas a significant correlation was observed between herpesviruses positivity and influenza virus infection. A higher ICU mortality was significantly related to the presence of herpesvirus infection in the lower respiratory tract as well as to impaired immunophenotype, as patients with poor outcome showed severe lymphopenia, affecting in particular T (CD3+) cells, since the first days of ICU hospitalization. In conclusion, these results indicate that herpesviruses lower respiratory tract infection, which occurs more frequently following influenza virus infection, can be a negative prognostic marker. An independent risk factor for ICU patients with ARDS is an impaired immunophenotype.

NADH:ubiquinone reductase and succinate dehydrogenase activity in the liver of rats with acetaminophen-induced toxic hepatitis on the background of alimentary protein deficiency

Directory of Open Access Journals (Sweden)

G. P. Kopylchuk

2015-02-01

Full Text Available The ratio between the redox forms of the nicotinamide coenzymes and key enzymatic activity of the I and II respiratory chain complexes in the liver cells mitochondria of rats with acetaminophen-induced hepatitis under the conditions of alimentary deprivation of protein was studied. It was estimated, that under the conditions of acute acetaminophen-induced hepatitis of rats kept on a low-protein diet during 4 weeks a significant decrease of the NADH:ubiquinone reductase and succinate dehydrogenase activity with simultaneous increase of the ratio between redox forms of the nicotinamide coenzymes (NAD+/NADН is observed compared to the same indices in the liver cells of animals with experimental hepatitis kept on the ration balanced by all nutrients. Results of research may become basic ones for the biochemical rationale for the approaches directed to the correction and elimination of the consequences­ of energy exchange in the toxic hepatitis, induced on the background of protein deficiency.

Prevention of hemodynamic and vascular albumin filtration changes in diabetic rats by aldose reductase inhibitors

International Nuclear Information System (INIS)

Tilton, R.G.; Chang, K.; Pugliese, G.; Eades, D.M.; Province, M.A.; Sherman, W.R.; Kilo, C.; Williamson, J.R.

1989-01-01

This study investigated hemodynamic changes in diabetic rats and their relationship to changes in vascular albumin permeation and increased metabolism of glucose to sorbitol. The effects of 6 wk of streptozocin-induced diabetes and three structurally different inhibitors of aldose reductase were examined on (1) regional blood flow (assessed with 15-microns 85Sr-labeled microspheres) and vascular permeation by 125I-labeled bovine serum albumin (BSA) and (2) glomerular filtration rate (assessed by plasma clearance of 57Co-labeled EDTA) and urinary albumin excretion (determined by radial immunodiffusion assay). In diabetic rats, blood flow was significantly increased in ocular tissues (anterior uvea, posterior uvea, retina, and optic nerve), sciatic nerve, kidney, new granulation tissue, cecum, and brain. 125I-BSA permeation was increased in all of these tissues except brain. Glomerular filtration rate and 24-h urinary albumin excretion were increased 2- and 29-fold, respectively, in diabetic rats. All three aldose reductase inhibitors completely prevented or markedly reduced these hemodynamic and vascular filtration changes and increases in tissue sorbitol levels in the anterior uvea, posterior uvea, retina, sciatic nerve, and granulation tissue. These observations indicate that early diabetes-induced hemodynamic changes and increased vascular albumin permeation and urinary albumin excretion are aldose reductase-linked phenomena. Discordant effects of aldose reductase inhibitors on blood flow and vascular albumin permeation in some tissues suggest that increased vascular albumin permeation is not entirely attributable to hemodynamic change

Cloning, expression and antigenicity of the L. donovani reductase

DEFF Research Database (Denmark)

Jensen, A T; Kemp, K; Theander, T G

2001-01-01

(K). Only 2 of 22 plasma samples from patients with visceral leishmaniasis were found to have detectable anti-reductase antibodies and peripheral blood mononuclear cells (PBMC) from one of three individuals previously infected with visceral leishmaniasis proliferated in the presence of recombinant...

A New Type of YumC-Like Ferredoxin (Flavodoxin) Reductase Is Involved in Ribonucleotide Reduction

DEFF Research Database (Denmark)

Chen, Jun; Shen, Jing; Solem, Christian

2015-01-01

. subtilis but that the addition of deoxynucleosides cannot compensate for the lethal phenotype displayed by the B. subtilis yumC knockout mutant. Ferredoxin (flavodoxin) reductase (FdR) is involved in many important reactions in both eukaryotes and prokaryotes, such as photosynthesis, nitrate reduction, etc. The recently...... ribonucleotide reductase, which represents the workhorse for the bioconversion of nucleotides to deoxynucleotides in many prokaryotes and eukaryotic pathogens under aerobic conditions. As the partner of the flavodoxin (NrdI), the key FdR is missing in the current model describing the class Ib system...

The Effects of Arbuscular-Mycorrhizal Fungi and Phosphorous on Arsenic Uptake by Sunflower Plant in Soils Spiked with Arsenite and Arsenate

Directory of Open Access Journals (Sweden)

Saeed Bagherifam

2017-01-01

Full Text Available Introduction: Arsenic is a highly toxic metalloid in group 15 of periodic table. The information on environmental behaviour of arsenic, however, is still scarce. Contamination of soils and water with arsenic and antimony due to their widespread industrial application and mining activities has raised serious environmental concerns. Nearly all Arsenic-contaminated soils results from human activities and it has different environmental and sociological impacts. Various strategies and methods have been proposed for environmental management and remediation of contaminated soils. Among all methods, the phytoremediation is receiving more attention due to its cost effective and environmental friendly characteristics. In the case of arsenic contaminated soils, there are effective factors such as soil fertility, nutrients content and microorganisms function, which can improve the uptake of As by plants. Up to now, several studies have been evaluated the effects of symbiotic fungal association in plants on increasing nutrients and toxic elements uptake. Many of authors reported that the mycorrhizal symbiosis increases the uptake of toxic elements in root and shoot of plants and consequently improve the efficacy of phytostabilization and phytoextraction processes. There are conflicting results about the effect of arbuscular- mycorrhizal fungi (AMF on As uptake by various plants. Chen et al. (4 found that Glomus mosseae symbiosis with plant reduces As concentration and enhance phosphorus content in shoot and root of plant. Whilst Cozzolino et al. (7 reported that the AMF increases as concentration in shoot and root of cabbage. Phosphorus has important role on mycorrhizal symbiosis and also As uptake by plants. Therefore, current study was conducted to evaluated effect of Glomus intraradices and Glomus mosseae symbiosis with sunflower and also soil phosphorus concentration on uptake of arsenic from arsenite and arsenate contaminated soils. Materials and

Neonatal respiratory distress syndrome

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Hyaline membrane disease (HMD); Infant respiratory distress syndrome; Respiratory distress syndrome in infants; RDS - infants ... improves slowly after that. Some infants with severe respiratory distress syndrome will die. This most often occurs ...

Activation of respiratory muscles during respiratory muscle training.

Science.gov (United States)

Walterspacher, Stephan; Pietsch, Fabian; Walker, David Johannes; Röcker, Kai; Kabitz, Hans-Joachim

2018-01-01

It is unknown which respiratory muscles are mainly activated by respiratory muscle training. This study evaluated Inspiratory Pressure Threshold Loading (IPTL), Inspiratory Flow Resistive Loading (IFRL) and Voluntary Isocapnic Hyperpnea (VIH) with regard to electromyographic (EMG) activation of the sternocleidomastoid muscle (SCM), parasternal muscles (PARA) and the diaphragm (DIA) in randomized order. Surface EMG were analyzed at the end of each training session and normalized using the peak EMG recorded during maximum inspiratory maneuvers (Sniff nasal pressure: SnPna, maximal inspiratory mouth occlusion pressure: PImax). 41 healthy participants were included. Maximal activation was achieved for SCM by SnPna; the PImax activated predominantly PARA and DIA. Activations of SCM and PARA were higher in IPTL and VIH than for IFRL (p<0.05). DIA was higher applying IPTL compared to IFRL or VIH (p<0.05). IPTL, IFRL and VIH differ in activation of inspiratory respiratory muscles. Whereas all methods mainly stimulate accessory respiratory muscles, diaphragm activation was predominant in IPTL. Copyright © 2017 Elsevier B.V. All rights reserved.

Respiratory trace feature analysis for the prediction of respiratory-gated PET quantification

Science.gov (United States)

Wang, Shouyi; Bowen, Stephen R.; Chaovalitwongse, W. Art; Sandison, George A.; Grabowski, Thomas J.; Kinahan, Paul E.

2014-02-01

The benefits of respiratory gating in quantitative PET/CT vary tremendously between individual patients. Respiratory pattern is among many patient-specific characteristics that are thought to play an important role in gating-induced imaging improvements. However, the quantitative relationship between patient-specific characteristics of respiratory pattern and improvements in quantitative accuracy from respiratory-gated PET/CT has not been well established. If such a relationship could be estimated, then patient-specific respiratory patterns could be used to prospectively select appropriate motion compensation during image acquisition on a per-patient basis. This study was undertaken to develop a novel statistical model that predicts quantitative changes in PET/CT imaging due to respiratory gating. Free-breathing static FDG-PET images without gating and respiratory-gated FDG-PET images were collected from 22 lung and liver cancer patients on a PET/CT scanner. PET imaging quality was quantified with peak standardized uptake value (SUVpeak) over lesions of interest. Relative differences in SUVpeak between static and gated PET images were calculated to indicate quantitative imaging changes due to gating. A comprehensive multidimensional extraction of the morphological and statistical characteristics of respiratory patterns was conducted, resulting in 16 features that characterize representative patterns of a single respiratory trace. The six most informative features were subsequently extracted using a stepwise feature selection approach. The multiple-regression model was trained and tested based on a leave-one-subject-out cross-validation. The predicted quantitative improvements in PET imaging achieved an accuracy higher than 90% using a criterion with a dynamic error-tolerance range for SUVpeak values. The results of this study suggest that our prediction framework could be applied to determine which patients would likely benefit from respiratory motion compensation

Respiratory trace feature analysis for the prediction of respiratory-gated PET quantification

International Nuclear Information System (INIS)

Wang, Shouyi; Chaovalitwongse, W Art; Bowen, Stephen R; Kinahan, Paul E; Sandison, George A; Grabowski, Thomas J

2014-01-01

The benefits of respiratory gating in quantitative PET/CT vary tremendously between individual patients. Respiratory pattern is among many patient-specific characteristics that are thought to play an important role in gating-induced imaging improvements. However, the quantitative relationship between patient-specific characteristics of respiratory pattern and improvements in quantitative accuracy from respiratory-gated PET/CT has not been well established. If such a relationship could be estimated, then patient-specific respiratory patterns could be used to prospectively select appropriate motion compensation during image acquisition on a per-patient basis. This study was undertaken to develop a novel statistical model that predicts quantitative changes in PET/CT imaging due to respiratory gating. Free-breathing static FDG-PET images without gating and respiratory-gated FDG-PET images were collected from 22 lung and liver cancer patients on a PET/CT scanner. PET imaging quality was quantified with peak standardized uptake value (SUV peak ) over lesions of interest. Relative differences in SUV peak between static and gated PET images were calculated to indicate quantitative imaging changes due to gating. A comprehensive multidimensional extraction of the morphological and statistical characteristics of respiratory patterns was conducted, resulting in 16 features that characterize representative patterns of a single respiratory trace. The six most informative features were subsequently extracted using a stepwise feature selection approach. The multiple-regression model was trained and tested based on a leave-one-subject-out cross-validation. The predicted quantitative improvements in PET imaging achieved an accuracy higher than 90% using a criterion with a dynamic error-tolerance range for SUV peak values. The results of this study suggest that our prediction framework could be applied to determine which patients would likely benefit from respiratory motion

What Is Respiratory Distress Syndrome?

Science.gov (United States)

... Home / Respiratory Distress Syndrome Respiratory Distress Syndrome Also known as What Is Respiratory ... This condition is called apnea (AP-ne-ah). Respiratory Distress Syndrome Complications Depending on the severity of ...

Microbial production of branched-chain dicarboxylate 2-methylsuccinic acid via enoate reductase-mediated bioreduction.

Science.gov (United States)

Wang, Jian; Yang, Yaping; Zhang, Ruihua; Shen, Xiaolin; Chen, Zhenya; Wang, Jia; Yuan, Qipeng; Yan, Yajun

2018-01-01

2-Methylsuccinic acid (2-MSA) is a C5 branched-chain dicarboxylate that serves as an attractive synthon for the synthesis of polymers with extensive applications in coatings, cosmetic solvents and bioplastics. However, the lack of natural pathways for 2-MSA biosynthesis has limited its application as a promising bio-replacement. Herein, we conceived a non-natural three-step biosynthetic route for 2-MSA, via employing the citramalate pathway in combination with enoate reductase-mediated bioreduction of the pathway intermediate citraconate. First, over-expression of codon-optimized citramalate synthase variant CimA* from Methanococcus jannaschii, endogenous isopropylmalate isomerase EcLeuCD and enoate reductase YqjM from Bacillus subtilis allowed the production of 2-MSA in Escherichia coli for the first time, with a titer of 0.35g/L in shake flask experiments. Subsequent screening of YqjM-like enoate reductases of different bacterial origins enabled identification and characterization of a new NAD(P)H-dependent enoate reductase KpnER from Klebsiella pneumoniae, which exhibited higher activity towards citraconate than YqjM. Incorporation of KpnER into the 2-MSA biosynthetic pathway led to 2-MSA production improvement to a titer of 0.96g/L in aerobic condition. Subsequent optimizations including cofactor regeneration, microaerobic cultivation and host strain engineering, boosted 2-MSA titer to 3.61g/L with a molar yield of 0.36 in shake flask experiments. This work established a promising platform for 2-MSA bioproduction, which enabled the highest titer of 2-MSA production in microbial hosts so far. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Functional Characterization of Four Putative δ1-Pyrroline-5-Carboxylate Reductases from Bacillus subtilis

Energy Technology Data Exchange (ETDEWEB)

Forlani, Giuseppe; Nocek, Boguslaw; Chakravarthy, Srinivas; Joachimiak, Andrzej

2017-08-02

In most living organisms, the amino acid proline is synthesized starting from both glutamate and ornithine. In prokaryotes, in the absence of an ornithine cyclodeaminase that has been identified to date only in a small number of soil and plant bacteria, these pathways share the last step, the reduction of δ1-pyrroline-5-carboxylate (P5C) catalyzed by P5C reductase (EC 1.5.1.2). In several species, multiple forms of P5C reductase have been reported, possibly reflecting the dual function of proline. Aside from its common role as a building block of proteins, proline is indeed also involved in the cellular response to osmotic and oxidative stress conditions. Genome analysis of Bacillus subtilis identifies the presence of four genes (ProH, ProI, ProG, and ComER) that, based on bioinformatic and phylogenic studies, were defined as respectively coding a putative P5C reductase. Here we describe the cloning, heterologous expression, functional analysis and small-angle X-ray scattering studies of the four affinity-purified proteins. Results showed that two of them, namely ProI and ComER, lost their catalytic efficiency or underwent subfunctionalization. In the case of ComER, this could be likely explained by the loss of the ability to form a dimer, which has been previously shown to be an essential structural feature of the catalytically active P5C reductase. The properties of the two active enzymes are consistent with a constitutive role for ProG, and suggest that ProH expression may be beneficial to satisfy an increased need for proline.

Functional Characterization of Four Putative δ1-Pyrroline-5-Carboxylate Reductases from Bacillus subtilis

Energy Technology Data Exchange (ETDEWEB)

Forlani, Giuseppe; Nocek, Boguslaw; Chakravarthy, Srinivas; Joachimiak, Andrzej

2017-08-02

In most living organisms, the amino acid proline is synthesized starting from both glutamate and ornithine. In prokaryotes, in the absence of an ornithine cyclodeaminase that has been identified to date only in a small number of soil and plant bacteria, these pathways share the last step, the reduction of delta(1)-pyrroline-5-carboxylate (P5C) catalyzed by P5C reductase (EC 1.5.1.2). In several species, multiple forms of P5C reductase have been reported, possibly reflecting the dual function of proline. Aside from its common role as a building block of proteins, proline is indeed also involved in the cellular response to osmotic and oxidative stress conditions. Genome analysis of Bacillus subtilis identifies the presence of four genes (ProH, ProI, ProG, and ComER) that, based on bioinformatic and phylogenic studies, were defined as respectively coding a putative P5C reductase. Here we describe the cloning, heterologous expression, functional analysis and small-angle X-ray scattering studies of the four affinity-purified proteins. Results showed that two of them, namely ProI and ComER, lost their catalytic efficiency or underwent subfunctionalization. In the case of ComER, this could be likely explained by the loss of the ability to form a dimer, which has been previously shown to be an essential structural feature of the catalytically active P5C reductase. The properties of the two active enzymes are consistent with a constitutive role for ProG, and suggest that ProH expression may be beneficial to satisfy an increased need for proline.

Functional Characterization of Four Putative δ1-Pyrroline-5-Carboxylate Reductases from Bacillus subtilis

Directory of Open Access Journals (Sweden)

Giuseppe Forlani

2017-08-01

Full Text Available In most living organisms, the amino acid proline is synthesized starting from both glutamate and ornithine. In prokaryotes, in the absence of an ornithine cyclodeaminase that has been identified to date only in a small number of soil and plant bacteria, these pathways share the last step, the reduction of δ1-pyrroline-5-carboxylate (P5C catalyzed by P5C reductase (EC 1.5.1.2. In several species, multiple forms of P5C reductase have been reported, possibly reflecting the dual function of proline. Aside from its common role as a building block of proteins, proline is indeed also involved in the cellular response to osmotic and oxidative stress conditions. Genome analysis of Bacillus subtilis identifies the presence of four genes (ProH, ProI, ProG, and ComER that, based on bioinformatic and phylogenic studies, were defined as respectively coding a putative P5C reductase. Here we describe the cloning, heterologous expression, functional analysis and small-angle X-ray scattering studies of the four affinity-purified proteins. Results showed that two of them, namely ProI and ComER, lost their catalytic efficiency or underwent subfunctionalization. In the case of ComER, this could be likely explained by the loss of the ability to form a dimer, which has been previously shown to be an essential structural feature of the catalytically active P5C reductase. The properties of the two active enzymes are consistent with a constitutive role for ProG, and suggest that ProH expression may be beneficial to satisfy an increased need for proline.

Neurological Respiratory Failure

Directory of Open Access Journals (Sweden)

Mohan Rudrappa

2018-01-01

Full Text Available West Nile virus infection in humans is mostly asymptomatic. Less than 1% of neuro-invasive cases show a fatality rate of around 10%. Acute flaccid paralysis of respiratory muscles leading to respiratory failure is the most common cause of death. Although the peripheral nervous system can be involved, isolated phrenic nerve palsy leading to respiratory failure is rare and described in only two cases in the English literature. We present another case of neurological respiratory failure due to West Nile virus-induced phrenic nerve palsy. Our case reiterates the rare, but lethal, consequences of West Nile virus infection, and the increase of its awareness among physicians.

Overexpression of Soybean Isoflavone Reductase (GmIFR) Enhances Resistance to Phytophthora sojae in Soybean.

Science.gov (United States)

Cheng, Qun; Li, Ninghui; Dong, Lidong; Zhang, Dayong; Fan, Sujie; Jiang, Liangyu; Wang, Xin; Xu, Pengfei; Zhang, Shuzhen

2015-01-01

Isoflavone reductase (IFR) is an enzyme involved in the biosynthetic pathway of isoflavonoid phytoalexin in plants. IFRs are unique to the plant kingdom and are considered to have crucial roles in plant response to various biotic and abiotic environmental stresses. Here, we report the characterization of a novel member of the soybean isoflavone reductase gene family GmIFR. Overexpression of GmIFR transgenic soybean exhibited enhanced resistance to Phytophthora sojae. Following stress treatments, GmIFR was significantly induced by P. sojae, ethephon (ET), abscisic acid (placeCityABA), salicylic acid (SA). It is located in the cytoplasm when transiently expressed in soybean protoplasts. The daidzein levels reduced greatly for the seeds of transgenic plants, while the relative content of glyceollins in transgenic plants was significantly higher than that of non-transgenic plants. Furthermore, we found that the relative expression levels of reactive oxygen species (ROS) of transgenic soybean plants were significantly lower than those of non-transgenic plants after incubation with P. sojae, suggesting an important role of GmIFR might function as an antioxidant to reduce ROS in soybean. The enzyme activity assay suggested that GmIFR has isoflavone reductase activity.

Association study of methylenetetrahydrofolate reductase C677T mutation with cerebral venous thrombosis in an Iranian population.

Science.gov (United States)

Ghaznavi, Habib; Soheili, Zahra; Samiei, Shahram; Soltanpour, Mohammad S

2015-12-01

There are limited data on the role of methylenetetrahydrofolate reductase C677T polymorphism and hyperhomocysteinemia as risk factors for cerebral venous thrombosis in Iranian population. We examined a possible association between fasting plasma homocysteine levels, methylenetetrahydrofolate reductase C677T polymorphism, and cerebral venous thrombosis in 50 patients with a diagnosis of cerebral venous thrombosis (20-63 years old) and 75 healthy controls (18-65 years old). Genotyping of the methylenetetrahydrofolate reductase C677T gene polymorphism was performed by PCR-restriction fragment length polymorphism analysis, and homocysteine levels were measured by enzyme immunoassay. Fasting plasma homocysteine levels were significantly higher in cerebral venous thrombosis patients than in controls (P = 0.015). Moreover, plasma homocysteine levels were significantly higher in methylenetetrahydrofolate reductase 677TT genotype compared to 677CT and 677CC genotypes in both cerebral venous thrombosis patients (P = 0.01) and controls (P = 0.03). Neither 677CT heterozygote genotype [odds ratio (OR) 1.35, 95% confidence interval (CI) 0.64-2.84, P = 0.556] nor 677TT homozygote genotype (OR 1.73, 95% CI 0.32-9.21, P = 0.833) was significantly associated with cerebral venous thrombosis. Additionally, no significant differences in the frequency of 677T allele between cerebral venous thrombosis patients and controls were identified (OR 1.31, 95% CI 0.69-2.50, P = 0.512). In conclusion, our study demonstrated that elevated plasma homocysteine levels are significant risk factors for cerebral venous thrombosis. Also, methylenetetrahydrofolate reductase 677TT genotype is not linked with cerebral venous thrombosis, but is a determinant of elevated plasma homocysteine levels.

Severe acute respiratory syndrome (SARS)

Science.gov (United States)

SARS; Respiratory failure - SARS ... Complications may include: Respiratory failure Liver failure Heart failure ... 366. McIntosh K, Perlman S. Coronaviruses, including severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS). ...

The Drosophila carbonyl reductase sniffer prevents oxidative stress-induced neurodegeneration.

Science.gov (United States)

Botella, Jose A; Ulschmid, Julia K; Gruenewald, Christoph; Moehle, Christoph; Kretzschmar, Doris; Becker, Katja; Schneuwly, Stephan

2004-05-04

A growing body of evidence suggests that oxidative stress is a common underlying mechanism in the pathogenesis of neurodegenerative disorders such as Alzheimer's, Huntington's, Creutzfeld-Jakob and Parkinson's diseases. Despite the increasing number of reports finding a causal relation between oxidative stress and neurodegeneration, little is known about the genetic elements that confer protection against the deleterious effects of oxidation in neurons. We have isolated and characterized the Drosophila melanogaster gene sniffer, whose function is essential for preventing age-related neurodegeneration. In addition, we demonstrate that oxidative stress is a direct cause of neurodegeneration in the Drosophila central nervous system and that reduction of sniffer activity leads to neuronal cell death. The overexpression of the gene confers neuronal protection against oxygen-induced apoptosis, increases resistance of flies to experimental normobaric hyperoxia, and improves general locomotor fitness. Sniffer belongs to the family of short-chain dehydrogenase/reductase (SDR) enzymes and exhibits carbonyl reductase activity. This is the first in vivo evidence of the direct and important implication of this enzyme as a neuroprotective agent in the cellular defense mechanisms against oxidative stress.

Cytochrome b5 reductase is the component from neuronal synaptic plasma membrane vesicles that generates superoxide anion upon stimulation by cytochrome c

Directory of Open Access Journals (Sweden)

Alejandro K. Samhan-Arias

2018-05-01

Full Text Available In this work, we measured the effect of cytochrome c on the NADH-dependent superoxide anion production by synaptic plasma membrane vesicles from rat brain. In these membranes, the cytochrome c stimulated NADH-dependent superoxide anion production was inhibited by antibodies against cytochrome b5 reductase linking the production to this enzyme. Measurement of the superoxide anion radical generated by purified recombinant soluble and membrane cytochrome b5 reductase corroborates the production of the radical by different enzyme isoforms. In the presence of cytochrome c, a burst of superoxide anion as well as the reduction of cytochrome c by cytochrome b5 reductase was measured. Complex formation between both proteins suggests that cytochrome b5 reductase is one of the major partners of cytochrome c upon its release from mitochondria to the cytosol during apoptosis. Superoxide anion production and cytochrome c reduction are the consequences of the stimulated NADH consumption by cytochrome b5 reductase upon complex formation with cytochrome c and suggest a major role of this enzyme as an anti-apoptotic protein during cell death.

The structure of Lactococcus lactis thioredoxin reductase reveals molecular features of photo-oxidative damage

DEFF Research Database (Denmark)

Skjoldager, Nicklas; Bang, Maria Blanner; Rykær, Martin

2017-01-01

The NADPH-dependent homodimeric flavoenzyme thioredoxin reductase (TrxR) provides reducing equivalents to thioredoxin, a key regulator of various cellular redox processes. Crystal structures of photo-inactivated thioredoxin reductase (TrxR) from the Gram-positive bacterium Lactococcus lactis have...... been determined. These structures reveal novel molecular features that provide further insight into the mechanisms behind the sensitivity of this enzyme toward visible light. We propose that a pocket on the si-face of the isoalloxazine ring accommodates oxygen that reacts with photo-excited FAD...... thus be a widespread feature among bacterial TrxR with the described characteristics, which affords applications in clinical photo-therapy of drug-resistant bacteria....

Hydroxyurea-resistant vaccinia virus: overproduction of ribonucleotide reductase

International Nuclear Information System (INIS)

Slabaugh, M.B.; Mathews, C.K.

1986-01-01

Repeated passage of vaccinia virus in increasing concentrations of hydroxyurea followed by plaque purification resulted in the isolation of variants capable of growth in 5 mM hydroxyurea, a drug concentration which inhibited the reproduction of wild-type vaccinia virus 1000-fold. Analyses of viral protein synthesis by using [ 35 S]methionine pulse-labeling at intervals throughout the infection cycle revealed that all isolates overproduced a 34,000-molecular-weight (MW) early polypeptide. Measurement of ribonucleoside-diphosphate reductase activity after infection indicated that 4- to 10-fold more activity was induced by hydroxyurea-resistant viruses than by the wild-type virus. A two-step partial purification resulted in a substantial enrichment for the 34,000-MW protein from extracts of wild-type and hydroxyurea-resistant-virus-infected, but not mock-infected, cells. In the presence of the drug, the isolates incorporated [ 3 H]thymidine into DNA earlier and a rate substantially greater than that of the wild type, although the onset of DNA synthesis was delayed in both cases. The drug resistance trait was markedly unstable in all isolates. In the absence of selective pressure, plaque-purified isolated readily segregated progeny that displayed a wide range of resistance phenotypes. The results of this study indicate that vaccinia virus encodes a subunit of ribonucleotide reductase which is 34,000-MW early protein whose overproduction confers hydroxyurea resistance on reproducing viruses

YqhD. A broad-substrate range aldehyde reductase with various applications in production of biorenewable fuels and chemicals

Energy Technology Data Exchange (ETDEWEB)

Jarboe, Laura R. [Iowa State Univ., Ames, IA (United States). Dept. of Chemical and Biological Engineering

2011-01-15

The Escherichia coli NADPH-dependent aldehyde reductase YqhD has contributed to a variety of metabolic engineering projects for production of biorenewable fuels and chemicals. As a scavenger of toxic aldehydes produced by lipid peroxidation, YqhD has reductase activity for a broad range of short-chain aldehydes, including butyraldehyde, glyceraldehyde, malondialdehyde, isobutyraldehyde, methylglyoxal, propanealdehyde, acrolein, furfural, glyoxal, 3-hydroxypropionaldehyde, glycolaldehyde, acetaldehyde, and acetol. This reductase activity has proven useful for the production of biorenewable fuels and chemicals, such as isobutanol and 1,3- and 1,2-propanediol; additional capability exists for production of 1-butanol, 1-propanol, and allyl alcohol. A drawback of this reductase activity is the diversion of valuable NADPH away from biosynthesis. This YqhD-mediated NADPH depletion provides sufficient burden to contribute to growth inhibition by furfural and 5-hydroxymethyl furfural, inhibitory contaminants of biomass hydrolysate. The structure of YqhD has been characterized, with identification of a Zn atom in the active site. Directed engineering efforts have improved utilization of 3-hydroxypropionaldehyde and NADPH. Most recently, two independent projects have demonstrated regulation of yqhD by YqhC, where YqhC appears to function as an aldehyde sensor. (orig.)

Boletus edulis Nitrite Reductase Reduces Nitrite Content of Pickles and Mitigates Intoxication in Nitrite-intoxicated Mice.

Science.gov (United States)

Zhang, Weiwei; Tian, Guoting; Feng, Shanshan; Wong, Jack Ho; Zhao, Yongchang; Chen, Xiao; Wang, Hexiang; Ng, Tzi Bun

2015-10-08

Pickles are popular in China and exhibits health-promoting effects. However, nitrite produced during fermentation adversely affects health due to formation of methemoglobin and conversion to carcinogenic nitrosamine. Fruiting bodies of the mushroom Boletus edulis were capable of inhibiting nitrite production during pickle fermentation. A 90-kDa nitrite reductase (NiR), demonstrating peptide sequence homology to fungal nitrite reductase, was isolated from B. edulis fruiting bodies. The optimum temperature and pH of the enzyme was 45 °C and 6.8, respectively. B. edulis NiR was capable of prolonging the lifespan of nitrite-intoxicated mice, indicating that it had the action of an antidote. The enzyme could also eliminate nitrite from blood after intragastric administration of sodium nitrite, and after packaging into capsule, this nitrite-eliminating activity could persist for at least 120 minutes thus avoiding immediate gastric degradation. B. edulis NiR represents the first nitrite reductase purified from mushrooms and may facilitate subsequent applications.

Respiratory gating in cardiac PET

DEFF Research Database (Denmark)

Lassen, Martin Lyngby; Rasmussen, Thomas; Christensen, Thomas E

2017-01-01

BACKGROUND: Respiratory motion due to breathing during cardiac positron emission tomography (PET) results in spatial blurring and erroneous tracer quantification. Respiratory gating might represent a solution by dividing the PET coincidence dataset into smaller respiratory phase subsets. The aim...... of our study was to compare the resulting imaging quality by the use of a time-based respiratory gating system in two groups administered either adenosine or dipyridamole as the pharmacological stress agent. METHODS AND RESULTS: Forty-eight patients were randomized to adenosine or dipyridamole cardiac...... stress (82)RB-PET. Respiratory rates and depths were measured by a respiratory gating system in addition to registering actual respiratory rates. Patients undergoing adenosine stress showed a decrease in measured respiratory rate from initial to later scan phase measurements [12.4 (±5.7) vs 5.6 (±4...

Fresh insight to functioning of selected enzymes of the nitrogen cycle.

Science.gov (United States)

Eady, Robert R; Antonyuk, Svetlana V; Hasnain, S Samar

2016-04-01

The global nitrogen cycle is the process in which different forms of environmental N are interconverted by microorganisms either for assimilation into biomass or in respiratory energy-generating pathways. This short review highlights developments over the last 5 years in our understanding of functionality of nitrogenase, Cu-nitrite reductase, NO reductase and N2O reductase, complex metalloenzymes that catalyze electron/proton-coupled substrate reduction reactions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Streptococcus sanguinis Class Ib Ribonucleotide Reductase

Science.gov (United States)

Makhlynets, Olga; Boal, Amie K.; Rhodes, DeLacy V.; Kitten, Todd; Rosenzweig, Amy C.; Stubbe, JoAnne

2014-01-01

Streptococcus sanguinis is a causative agent of infective endocarditis. Deletion of SsaB, a manganese transporter, drastically reduces S. sanguinis virulence. Many pathogenic organisms require class Ib ribonucleotide reductase (RNR) to catalyze the conversion of nucleotides to deoxynucleotides under aerobic conditions, and recent studies demonstrate that this enzyme uses a dimanganese-tyrosyl radical (MnIII2-Y•) cofactor in vivo. The proteins required for S. sanguinis ribonucleotide reduction (NrdE and NrdF, α and β subunits of RNR; NrdH and TrxR, a glutaredoxin-like thioredoxin and a thioredoxin reductase; and NrdI, a flavodoxin essential for assembly of the RNR metallo-cofactor) have been identified and characterized. Apo-NrdF with FeII and O2 can self-assemble a diferric-tyrosyl radical (FeIII2-Y•) cofactor (1.2 Y•/β2) and with the help of NrdI can assemble a MnIII2-Y• cofactor (0.9 Y•/β2). The activity of RNR with its endogenous reductants, NrdH and TrxR, is 5,000 and 1,500 units/mg for the Mn- and Fe-NrdFs (Fe-loaded NrdF), respectively. X-ray structures of S. sanguinis NrdIox and MnII2-NrdF are reported and provide a possible rationale for the weak affinity (2.9 μm) between them. These streptococcal proteins form a structurally distinct subclass relative to other Ib proteins with unique features likely important in cluster assembly, including a long and negatively charged loop near the NrdI flavin and a bulky residue (Thr) at a constriction in the oxidant channel to the NrdI interface. These studies set the stage for identifying the active form of S. sanguinis class Ib RNR in an animal model for infective endocarditis and establishing whether the manganese requirement for pathogenesis is associated with RNR. PMID:24381172

Electrodialytic removal of Cu, Cr, and As from chromated copper arsenate-treated timber waste

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, A.B.; Mateus, E.P.; Ottosen, L.M.; Bech-Nielsen, G.

2000-03-01

Waste of wood treated with chromated copper arsenate (CCA) is expected to increase in volume over the next decades. Alternative disposal options to landfilling are becoming more attractive to study, especially those that promote reuse. The authors have studied the electrodialytic removal of Cu, Cr, and As from CCA-treated timber wastes. The method uses a low-level direct current as the cleaning agent, combining the electrokinetic movement of ions in the matrix with the principle of electrodialysis. The technique was tested in four experiments using a laboratory cell on sawdust of an out-of-service CCA-treated Pinus pinaster Ait. pole. The duration of all the experiments was 30 days, and the current density was kept constant at 0.2 mA/cm{sup 2}. The experiments differ because in one the sawdust was saturated with water (experiment 1) and in the rest it was saturated with oxalic acid, 2.5, 5, and 7.5% (w/w), respectively, in experiments 2--4. The highest removal rates obtained were 93% of Cu, 95% of Cr, and 99% of As in experiment 2. Other experimental conditions might possibly optimize the removal rates.

Engineered coryneform bacteria as a bio-tool for arsenic remediation.

Science.gov (United States)

Villadangos, Almudena F; Ordóñez, Efrén; Pedre, Brandán; Messens, Joris; Gil, Jose A; Mateos, Luis M

2014-12-01

Despite current remediation efforts, arsenic contamination in water sources is still a major health problem, highlighting the need for new approaches. In this work, strains of the nonpathogenic and highly arsenic-resistant bacterium Corynebacterium glutamicum were used as inexpensive tools to accumulate inorganic arsenic, either as arsenate (As(V)) or arsenite (As(III)) species. The assays made use of "resting cells" from these strains, which were assessed under well-established conditions and compared with C. glutamicum background controls. The two mutant As(V)-accumulating strains were those used in a previously published study: (i) ArsC1/C2, in which the gene/s encoding the mycothiol-dependent arsenate reductases is/are disrupted, and (ii) MshA/C mutants unable to produce mycothiol, the low molecular weight thiol essential for arsenate reduction. The As(III)-accumulating strains were either those lacking the arsenite permease activities (Acr3-1 and Acr3-2) needed in As(III) release or recombinant strains overexpressing the aquaglyceroporin genes (glpF) from Corynebacterium diphtheriae or Streptomyces coelicolor, to improve As(III) uptake. Both genetically modified strains accumulated 30-fold more As(V) and 15-fold more As(III) than the controls. The arsenic resistance of the modified strains was inversely proportional to their metal accumulation ability. Our results provide the basis for investigations into the use of these modified C. glutamicum strains as a new bio-tool in arsenic remediation efforts.

Respiratory and metabolic acidosis differentially affect the respiratory neuronal network in the ventral medulla of neonatal rats.

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Okada, Yasumasa; Masumiya, Haruko; Tamura, Yoshiyasu; Oku, Yoshitaka

2007-11-01

Two respiratory-related areas, the para-facial respiratory group/retrotrapezoid nucleus (pFRG/RTN) and the pre-Bötzinger complex/ventral respiratory group (preBötC/VRG), are thought to play key roles in respiratory rhythm. Because respiratory output patterns in response to respiratory and metabolic acidosis differ, we hypothesized that the responses of the medullary respiratory neuronal network to respiratory and metabolic acidosis are different. To test these hypotheses, we analysed respiratory-related activity in the pFRG/RTN and preBötC/VRG of the neonatal rat brainstem-spinal cord in vitro by optical imaging using a voltage-sensitive dye, and compared the effects of respiratory and metabolic acidosis on these two populations. We found that the spatiotemporal responses of respiratory-related regional activities to respiratory and metabolic acidosis are fundamentally different, although both acidosis similarly augmented respiratory output by increasing respiratory frequency. PreBötC/VRG activity, which is mainly inspiratory, was augmented by respiratory acidosis. Respiratory-modulated pixels increased in the preBötC/VRG area in response to respiratory acidosis. Metabolic acidosis shifted the respiratory phase in the pFRG/RTN; the pre-inspiratory dominant pattern shifted to inspiratory dominant. The responses of the pFRG/RTN activity to respiratory and metabolic acidosis are complex, and involve either augmentation or reduction in the size of respiratory-related areas. Furthermore, the activation pattern in the pFRG/RTN switched bi-directionally between pre-inspiratory/inspiratory and post-inspiratory. Electrophysiological study supported the results of our optical imaging study. We conclude that respiratory and metabolic acidosis differentially affect activities of the pFRG/RTN and preBötC/VRG, inducing switching and shifts of the respiratory phase. We suggest that they differently influence the coupling states between the pFRG/RTN and preBötC/VRG.

Lungs and Respiratory System

Science.gov (United States)

... Videos for Educators Search English Español Lungs and Respiratory System KidsHealth / For Parents / Lungs and Respiratory System ... ll have taken at least 600 million breaths. Respiratory System Basics All of this breathing couldn't ...

Effect of transoral tracheal wash on respiratory mechanics in dogs with respiratory disease.

Science.gov (United States)

Vaught, Meghan E; Rozanski, Elizabeth A; deLaforcade, Armelle M

2018-01-01

The purpose of this study was to determine the impact of a transoral tracheal wash (TOTW) on respiratory mechanics in dogs and to describe the use of a critical care ventilator (CCV) to determine respiratory mechanics. Fourteen client-owned dogs with respiratory diseases were enrolled. Respiratory mechanics, including static compliance (C stat ) and static resistance (R stat ), were determined before and after TOTW. Pre- and post-wash results were compared, with a P -value of mechanics, as observed by a reduction in C stat , presumably due to airway flooding and collapse. While no long-lasting effects were noted in these clinical patients, this effect should be considered when performing TOTW on dogs with respiratory diseases. Respiratory mechanics testing using a CCV was feasible and may be a useful clinical testing approach.

Cancer cell death induced by phosphine gold(I) compounds targeting thioredoxin reductase.

Science.gov (United States)

Gandin, Valentina; Fernandes, Aristi Potamitou; Rigobello, Maria Pia; Dani, Barbara; Sorrentino, Francesca; Tisato, Francesco; Björnstedt, Mikael; Bindoli, Alberto; Sturaro, Alberto; Rella, Rocco; Marzano, Cristina

2010-01-15

The thioredoxin system, composed of thioredoxin reductase (TrxR), thioredoxin (Trx), and NADPH (nicotinamide adenine dinucleotide phosphate), plays a central role in regulating cellular redox homeostasis and signaling pathways. TrxR, overexpressed in many tumor cells and contributing to drug resistance, has emerged as a new target for anticancer drugs. Gold complexes have been validated as potent TrxR inhibitors in vitro in the nanomolar range. In order to obtain potent and selective TrxR inhibitors, we have synthesized a series of linear, 'auranofin-like' gold(I) complexes all containing the [Au(PEt(3))](+) synthon and the ligands: Cl(-), Br(-), cyanate, thiocyanate, ethylxanthate, diethyldithiocarbamate and thiourea. Phosphine gold(I) complexes efficiently inhibited cytosolic and mitochondrial TrxR at concentrations that did not affect the two related oxidoreductases glutathione reductase (GR) and glutathione peroxidase (GPx). The inhibitory effect of the redox proteins was also observed intracellularly in cancer cells pretreated with gold(I) complexes. Gold(I) compounds were found to induce antiproliferative effects towards several human cancer cells some of which endowed with cisplatin or multidrug resistance. In addition, they were able to activate caspase-3 and induce apoptosis observed as nucleosome formation and sub-G1 cell accumulation. The complexes with thiocyanate and xanthate ligands were particularly effective in inhibiting thioredoxin reductase and inducing apoptosis. Pharmacodynamic studies in human ovarian cancer cells allowed for the correlation of intracellular drug accumulation with TrxR inhibition that leads to the induction of apoptosis via the mitochondrial pathway.

Characterisation of PduS, the pdu metabolosome corrin reductase, and evidence of substructural organisation within the bacterial microcompartment.

Directory of Open Access Journals (Sweden)

Joshua B Parsons

2010-11-01

Full Text Available PduS is a corrin reductase and is required for the reactivation of the cobalamin-dependent diol dehydratase. It is one component encoded within the large propanediol utilisation (pdu operon, which is responsible for the catabolism of 1,2-propanediol within a self-assembled proteinaceous bacterial microcompartment. The enzyme is responsible for the reactivation of the cobalamin coenzyme required by the diol dehydratase. The gene for the cobalamin reductase from Citrobacter freundii (pduS has been cloned to allow the protein to be overproduced recombinantly in E. coli with an N-terminal His-tag. Purified recombinant PduS is shown to be a flavoprotein with a non-covalently bound FMN that also contains two coupled [4Fe-4S] centres. It is an NADH-dependent flavin reductase that is able to mediate the one-electron reductions of cob(IIIalamin to cob(IIalamin and cob(IIalamin to cob(Ialamin. The [4Fe-4S] centres are labile to oxygen and their presence affects the midpoint redox potential of flavin. Evidence is presented that PduS is able to bind cobalamin, which is inconsistent with the view that PduS is merely a flavin reductase. PduS is also shown to interact with one of the shell proteins of the metabolosome, PduT, which is also thought to contain an [Fe-S] cluster. PduS is shown to act as a corrin reductase and its interaction with a shell protein could allow for electron passage out of the bacterial microcompartment.

X-ray crystal structure of GarR-tartronate semialdehyde reductase from Salmonella typhimurium.

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Osipiuk, J; Zhou, M; Moy, S; Collart, F; Joachimiak, A

2009-09-01

Tartronate semialdehyde reductases (TSRs), also known as 2-hydroxy-3-oxopropionate reductases, catalyze the reduction of tartronate semialdehyde using NAD as cofactor in the final stage of D-glycerate biosynthesis. These enzymes belong to family of structurally and mechanically related beta-hydroxyacid dehydrogenases which differ in substrate specificity and catalyze reactions in specific metabolic pathways. Here, we present the crystal structure of GarR a TSR from Salmonella typhimurium determined by the single-wavelength anomalous diffraction method and refined to 1.65 A resolution. The active site of the enzyme contains L-tartrate which most likely mimics a position of a glycerate which is a product of the enzyme reaction. The analysis of the TSR structure shows also a putative NADPH binding site in the enzyme.

[Aldose reductase gene polymorphism and rate of appearance of retinopathy in non insulin dependent diabetics].

Science.gov (United States)

Olmos, P; Acosta, A M; Schiaffino, R; Díaz, R; Alvarado, D; O'Brien, A; Muñoz, X; Arriagada, P; Claro, J C; Vega, R; Vollrath, V; Velasco, S; Emmerich, M; Maiz, A

1999-04-01

Recent studies suggest that polymorphisms associated to the aldose reductase gene could be related to early retinopathy in noninsulin dependent diabetics (NIDDM). There is also new interest on the genetic modulation of coagulation factors in relation to this complication. To look for a possible relationship between the rate of appearance of retinopathy and the genotype of (AC)n polymorphic marker associated to aldose reductase gene. A random sample of 27 NIDDM, aged 68.1 +/- 10.6 years, with a mean diabetes duration of 20.7 +/- 4.8 years and a mean glycosilated hemoglobin of 10.6 +/- 1.6%, was studied. The genotype of the (AC)n, polymorphic marker associated to the 5' end of the aldose reductase (ALR2) gene was determined by 32P-PCR plus sequenciation. Mutations of the factor XIII-A gene were studied by single stranded conformational polymorphism, sequenciation and restriction fragment length polymorphism. Four patients lacked the (AC)24 and had a higher rate of appearance of retinopathy than patients with the (AC)24 allele (0.0167 and 0.0907 score points per year respectively, p = 0.047). Both groups had similar glycosilated hemoglobin (11.7 +/- 0.2 and 10.5 +/- 1.6% respectively). Factor XIII gene mutations were not related to the rate of appearance of retinopathy. Our data suggest that the absence of the (AC)24 allele of the (AC)n polymorphic marker associated to the 5' end of the aldose reductase gene, is associated to a five fold reduction of retinopathy appearance rate.

New inorganic (an)ion exchangers with a higher affinity for arsenate and a competitive removal capacity towards fluoride, bromate, bromide, selenate, selenite, arsenite and borate

KAUST Repository

Chubar, Natalia

2011-12-01

Highly selective materials and effective technologies are needed to meet the increasingly stronger drinking water standards for targeted ionic species. Inorganic ion exchangers based on individual and mixed-metal hydrous oxides (or mixed adsorbents that contain inorganic ion exchangers in their composition) are adsorptive materials that are capable of lowering the concentrations of anionic contaminants, such as H 2AsO 4 -, H 3AsO 3, F -, Br -, BrO 3 -, HSeO 4 -, HSeO 3 - and H 3BO 3, to 10 μg/L or less. To achieve a higher selectivity towards arsenate, a new ion exchanger based on Mg-Al hydrous oxides was developed by a novel, cost-effective and environmentally friendly synthesis method via a non-traditional (alkoxide-free) sol-gel approach. The exceptional adsorptive capacity of the Mg-Al hydrous oxides towards H 2AsO 4 - (up to 200 mg[As]/gdw) is due to the high affinity of this sorbent towards arsenate (steep equilibrium isotherms) and its fast adsorption kinetics. Because of the mesoporous (as determined by N 2 adsorption and SEM) and layered (as determined by XRD and FTIR) structure of the ion-exchange material as well as the abundance of anion exchange sites (as determined by XPS and potentiometric titration) on its surface the material demonstrated very competitive (or very high) removal capacity towards other targeted anions, including fluoride, bromide, bromate, selenate, selenite, and borate. © 2011 IWA Publishing.

HMG-CoA reductase inhibitory activity and phytocomponent investigation of Basella alba leaf extract as a treatment for hypercholesterolemia

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Baskaran G

2015-01-01

Full Text Available Gunasekaran Baskaran,1 Shamala Salvamani,1 Siti Aqlima Ahmad,1 Noor Azmi Shaharuddin,1 Parveen Devi Pattiram,2 Mohd Yunus Shukor1 1Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, 2Department of Food Technology, Faculty of Food Science and Technology, Universiti Putra Malaysia, Selangor, Malaysia Abstract: The enzyme 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA reductase is the key enzyme of the mevalonate pathway that produces cholesterol. Inhibition of HMG-CoA reductase reduces cholesterol biosynthesis in the liver. Synthetic drugs, statins, are commonly used for the treatment of hypercholesterolemia. Due to the side effects of statins, natural HMG-CoA reductase inhibitors of plant origin are needed. In this study, 25 medicinal plant methanol extracts were screened for anti-HMG-CoA reductase activity. Basella alba leaf extract showed the highest inhibitory effect at about 74%. Thus, B. alba was examined in order to investigate its phytochemical components. Gas chromatography with tandem mass spectrometry and reversed phase high-performance liquid chromatography analysis revealed the presence of phenol 2,6-bis(1,1-dimethylethyl, 1-heptatriacotanol, oleic acid, eicosyl ester, naringin, apigenin, luteolin, ascorbic acid, and a-tocopherol, which have been reported to possess antihypercholesterolemic effects. Further investigation of in vivo models should be performed in order to confirm its potential as an alternative treatment for hypercholesterolemia and related cardiovascular diseases. Keywords: HMG-CoA reductase, Basella alba, phytochemical, GC-MS/MS, RP-HPLC, hypercholesterolemia

Genetic and Biochemical Analysis of Intragenic Complementation Events among Nitrate Reductase Apoenzyme-Deficient Mutants of Nicotiana Plumbaginifolia

OpenAIRE

Pelsy, F.; Gonneau, M.

1991-01-01

Intragenic complementation has been observed between apoenzyme nitrate reductase-deficient mutants (nia) of Nicotiana plumbaginifolia. In vivo as in vitro, the NADH-nitrate reductase (NR) activity in plants heterozygous for two different nia alleles was lower than in the wild type plant, but the plants were able to grow on nitrate as a sole nitrogen source. NR activity, absent in extracts of homozygous nia mutants was restored by mixing extracts from two complementing nia mutants. These obser...

Colour formation in fermented sausages by meat-associated staphylococci with different nitrite- and nitrate-reductase activities.

Science.gov (United States)

Gøtterup, Jacob; Olsen, Karsten; Knøchel, Susanne; Tjener, Karsten; Stahnke, Louise H; Møller, Jens K S

2008-04-01

Three Staphylococcus strains, S. carnosus, S. simulans and S. saprophyticus, selected due to their varying nitrite and/or nitrate-reductase activities, were used to initiate colour formation during sausage fermentation. During fermentation of sausages with either nitrite or nitrate added, colour was followed by L(∗)a(∗)b measurements and the content of nitrosylmyoglobin (MbFe(II)NO) quantified by electron spin resonance (ESR). MbFe(II)NO was rapidly formed in sausages with added nitrite independent of the presence of nitrite reducing bacteria, whereas the rate of MbFe(II)NO formation in sausages with added nitrate depended on the specific Staphylococcus strain. Strains with high nitrate-reductase activity showed a significantly faster rate of pigment formation, but other factors were of influence as well. Product stability for the sliced, packaged sausage was evaluated as surface colour and oxidation by autofluorescence and hexanal content, respectively. No significant direct effect of the Staphylococcus addition was observed, however, there was a clear correspondence between high initial amount of MbFe(II)NO in the different sausages and the colour stability during storage. Autofluorescence data correlated well with hexanal content, and may be used as predictive tools. Overall, nitrite- and nitrate-reductase activities of Staphylococcus strains in nitrite-cured sausages were of limited importance regarding colour development, while in nitrate-cured sausages strains with higher nitrate reductase activity were crucial for ensuring optimal colour formation during initial fermentation stages.

Expression, purification, crystallization and preliminary X-ray analysis of maleylacetate reductase from Burkholderia sp. strain SJ98

International Nuclear Information System (INIS)

Chauhan, Archana; Islam, Zeyaul; Jain, Rakesh Kumar; Karthikeyan, Subramanian

2009-01-01

Purification and preliminary X-ray crystallographic analysis of maleylacetate reductase encoded by the pnpD gene is reported. Maleylacetate reductase (EC 1.3.1.32) is an important enzyme that is involved in the degradation pathway of aromatic compounds and catalyzes the reduction of maleylacetate to 3-oxoadipate. The gene pnpD encoding maleylacetate reductase in Burkholderia sp. strain SJ98 was cloned, expressed in Escherichia coli and purified by affinity chromatography. The enzyme was crystallized in both native and SeMet-derivative forms by the sitting-drop vapour-diffusion method using PEG 3350 as a precipitant at 293 K. The crystals belonged to space group P2 1 2 1 2, with unit-cell parameters a = 72.91, b = 85.94, c = 53.07 Å. X-ray diffraction data for the native and SeMet-derivative crystal were collected to 2.7 and 2.9 Å resolution, respectively

Determination of chromated copper arsenate (CCA) in treated wood of Eucalyptus

International Nuclear Information System (INIS)

Parreira, Paulo S.; Vendrametto, Guilherme R.; Cunha, Magda E.T.

2009-01-01

This work deals with the possible application of a portable energy dispersive handmade system (PXRF-LFNA-02) for the determination of Chromium, Copper and Arsenic in the preservative solution used to protect commercial wood of Eucalyptus, which are employed as wood fence, posts, contention fences, railroad sleepers, etc. It was prepared five body-of-proof made of eucalyptus alburnum with different concentrations for each element varying from 0.0061 to 0.0180 (g/g) for CrO 3 , 0.0024 to 0.0070 (g/g) for CuO and 0.0044 to 0.0129 (g/g) for As 2 O 5 . Four of them were used for calibration curves and one used as reference sample. It was used a commercial CCA (Chromated Copper Arsenate ) solution to prepare the samples. The results show a good linear regression between concentrations and X-rays intensities, after applied the multiple linear regression methodology for interelemental corrections. The values obtained with this methodology were 3.01(kg/m 3 ), 1.18 (kg/m 3 ) e 2.21 (kg/m 3 ) for CrO 3 , CuO and As 2 O 5 , respectively, while the nominal values are 2.90 (kg/m 3 ) for CrO 3 , 1.13 (kg/m 3 ) for CuO and 2.07 (kg/m 3 ) for As 2 O 5 . The ED-XRF (Energy Dispersive X-Rays Fluorescence) is a well established technique with high-speed of analytical procedure and its portable configuration allowing a multielemental, simultaneous and non destructive analyses besides in situ application. (author)

A novel twist on molecular interactions between thioredoxin and nicotinamide adenine dinucleotide phosphate-dependent thioredoxin reductase

DEFF Research Database (Denmark)

Kirkensgaard, Kristine Groth; Hägglund, Per; Shahpiri, Azar

2013-01-01

The ubiquitous disulfide reductase thioredoxin (Trx) regulates several important biological processes such as seed germination in plants. Oxidized cytosolic Trx is regenerated by nicotinamide adenine dinucleotide phosphate (NADPH)-dependent thioredoxin reductase (NTR) in a multistep transfer...... dinucleotide (FAD)-binding domain of HvNTR2 to strongly affect the interaction with Trx. In particular, Trp42 and Met43 play key roles for recognition of the endogenous HvTrxh2. Trx from Arabidopsis thaliana is also efficiently recycled by HvNTR2 but turnover in this case appears to be less dependent...

Managing respiratory problems in athletes.

Science.gov (United States)

Hull, James H; Ansley, Les; Robson-Ansley, Paula; Parsons, Jonathan P

2012-08-01

Respiratory problems are common in athletes of all abilities and can significantly impact upon their health and performance. In this article, we provide an overview of respiratory physiology in athletes. We also discuss the assessment and management of common clinical respiratory conditions as they pertain to athletes, including airways disease, respiratory tract infection and pneumothorax. We focus on providing a pragmatic approach and highlight important caveats for the physician treating respiratory conditions in this highly specific population.

Pichia stipitis xylose reductase helps detoxifying lignocellulosic hydrolysate by reducing 5-hydroxymethyl-furfural (HMF

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Röder Anja

2008-06-01

Full Text Available Abstract Background Pichia stipitis xylose reductase (Ps-XR has been used to design Saccharomyces cerevisiae strains that are able to ferment xylose. One example is the industrial S. cerevisiae xylose-consuming strain TMB3400, which was constructed by expression of P. stipitis xylose reductase and xylitol dehydrogenase and overexpression of endogenous xylulose kinase in the industrial S. cerevisiae strain USM21. Results In this study, we demonstrate that strain TMB3400 not only converts xylose, but also displays higher tolerance to lignocellulosic hydrolysate during anaerobic batch fermentation as well as 3 times higher in vitro HMF and furfural reduction activity than the control strain USM21. Using laboratory strains producing various levels of Ps-XR, we confirm that Ps-XR is able to reduce HMF both in vitro and in vivo. Ps-XR overexpression increases the in vivo HMF conversion rate by approximately 20%, thereby improving yeast tolerance towards HMF. Further purification of Ps-XR shows that HMF is a substrate inhibitor of the enzyme. Conclusion We demonstrate for the first time that xylose reductase is also able to reduce the furaldehyde compounds that are present in undetoxified lignocellulosic hydrolysates. Possible implications of this newly characterized activity of Ps-XR on lignocellulosic hydrolysate fermentation are discussed.

X-Ray crystal structure of GarR—tartronate semialdehyde reductase from Salmonella typhimurium

Science.gov (United States)

Osipiuk, J.; Zhou, M.; Moy, S.; Collart, F.

2009-01-01

Tartronate semialdehyde reductases (TSRs), also known as 2-hydroxy-3-oxopropionate reductases, catalyze the reduction of tartronate semialdehyde using NAD as cofactor in the final stage of D-glycerate biosynthesis. These enzymes belong to family of structurally and mechanically related β-hydroxyacid dehydrogenases which differ in substrate specificity and catalyze reactions in specific metabolic pathways. Here, we present the crystal structure of GarR a TSR from Salmonella typhimurium determined by the single-wavelength anomalous diffraction method and refined to 1.65 Å resolution. The active site of the enzyme contains L-tartrate which most likely mimics a position of a glycerate which is a product of the enzyme reaction. The analysis of the TSR structure shows also a putative NADPH binding site in the enzyme. PMID:19184529

Normal bone density in male pseudohermaphroditism due to 5a- reductase 2 deficiency

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Costa Elaine Maria Frade

2001-01-01

Full Text Available Bone is an androgen-dependent tissue, but it is not clear whether the androgen action in bone depends on testosterone or on dihydrotestosterone. Patients with 5alpha-reductase 2 deficiency present normal levels of testosterone and low levels of dihydrotestosterone, providing an in vivo human model for the analysis of the effect of testosterone on bone. OBJECTIVE: To analyze bone mineral density in 4 adult patients with male pseudohermaphroditism due to 5alpha-reductase 2 deficiency. RESULTS: Three patients presented normal bone mineral density of the lumbar column (L1-L4 and femur neck, and the other patient presented a slight osteopenia in the lumbar column. CONCLUSION: Patients with dihydrotestosterone deficiency present normal bone mineral density, suggesting that dihydrotestosterone is not the main androgen acting in bone.

The crystal structure of the bifunctional deaminase/reductase RibD of the riboflavin biosynthetic pathway in Escherichia coli: implications for the reductive mechanism.

Science.gov (United States)

Stenmark, Pål; Moche, Martin; Gurmu, Daniel; Nordlund, Pär

2007-10-12

We have determined the crystal structure of the bi-functional deaminase/reductase enzyme from Escherichia coli (EcRibD) that catalyzes two consecutive reactions during riboflavin biosynthesis. The polypeptide chain of EcRibD is folded into two domains where the 3D structure of the N-terminal domain (1-145) is similar to cytosine deaminase and the C-terminal domain (146-367) is similar to dihydrofolate reductase. We showed that EcRibD is dimeric and compared our structure to tetrameric RibG, an ortholog from Bacillus subtilis (BsRibG). We have also determined the structure of EcRibD in two binary complexes with the oxidized cofactor (NADP(+)) and with the substrate analogue ribose-5-phosphate (RP5) and superposed these two in order to mimic the ternary complex. Based on this superposition we propose that the invariant Asp200 initiates the reductive reaction by abstracting a proton from the bound substrate and that the pro-R proton from C4 of the cofactor is transferred to C1 of the substrate. A highly flexible loop is found in the reductase active site (159-173) that appears to control cofactor and substrate binding to the reductase active site and was therefore compared to the corresponding Met20 loop of E. coli dihydrofolate reductase (EcDHFR). Lys152, identified by comparing substrate analogue (RP5) coordination in the reductase active site of EcRibD with the homologous reductase from Methanocaldococcus jannaschii (MjaRED), is invariant among bacterial RibD enzymes and could contribute to the various pathways taken during riboflavin biosynthesis in bacteria and yeast.

Respiratory Syncytial Virus

Science.gov (United States)

... with facebook share with twitter share with linkedin Respiratory Syncytial Virus (RSV) Credit: CDC This is the ... the United States. Why Is the Study of Respiratory Syncytial Virus (RSV) a Priority for NIAID? In ...

Structural basis for high substrate-binding affinity and enantioselectivity of 3-quinuclidinone reductase AtQR

International Nuclear Information System (INIS)

Hou, Feng; Miyakawa, Takuya; Kataoka, Michihiko; Takeshita, Daijiro; Kumashiro, Shoko; Uzura, Atsuko; Urano, Nobuyuki; Nagata, Koji; Shimizu, Sakayu; Tanokura, Masaru

2014-01-01

Highlights: • Crystal structure of AtQR has been determined at 1.72 Å. • NADH binding induces the formation of substrate binding site. • AtQR possesses a conserved hydrophobic wall for stereospecific binding of substrate. • Additional Glu197 residue is critical to the high binding affinity. - Abstract: (R)-3-Quinuclidinol, a useful compound for the synthesis of various pharmaceuticals, can be enantioselectively produced from 3-quinuclidinone by 3-quinuclidinone reductase. Recently, a novel NADH-dependent 3-quinuclidionone reductase (AtQR) was isolated from Agrobacterium tumefaciens, and showed much higher substrate-binding affinity (>100 fold) than the reported 3-quinuclidionone reductase (RrQR) from Rhodotorula rubra. Here, we report the crystal structure of AtQR at 1.72 Å. Three NADH-bound protomers and one NADH-free protomer form a tetrameric structure in an asymmetric unit of crystals. NADH not only acts as a proton donor, but also contributes to the stability of the α7 helix. This helix is a unique and functionally significant part of AtQR and is related to form a deep catalytic cavity. AtQR has all three catalytic residues of the short-chain dehydrogenases/reductases family and the hydrophobic wall for the enantioselective reduction of 3-quinuclidinone as well as RrQR. An additional residue on the α7 helix, Glu197, exists near the active site of AtQR. This acidic residue is considered to form a direct interaction with the amine part of 3-quinuclidinone, which contributes to substrate orientation and enhancement of substrate-binding affinity. Mutational analyses also support that Glu197 is an indispensable residue for the activity

Structural basis for high substrate-binding affinity and enantioselectivity of 3-quinuclidinone reductase AtQR

Energy Technology Data Exchange (ETDEWEB)

Hou, Feng; Miyakawa, Takuya [Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657 (Japan); Kataoka, Michihiko [Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 559-8531 (Japan); Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Takeshita, Daijiro [Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657 (Japan); Kumashiro, Shoko [Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Uzura, Atsuko [Research and Development Center, Nagase and Co., Ltd., 2-2-3 Muratani, Nishi-ku, Kobe 651-2241 (Japan); Urano, Nobuyuki [Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 559-8531 (Japan); Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Nagata, Koji [Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657 (Japan); Shimizu, Sakayu [Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Faculty of Bioenvironmental Science, Kyoto Gakuen University, Sogabe-cho, Kameoka 621-8555 (Japan); Tanokura, Masaru, E-mail: amtanok@mail.ecc.u-tokyo.ac.jp [Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657 (Japan)

2014-04-18

Highlights: • Crystal structure of AtQR has been determined at 1.72 Å. • NADH binding induces the formation of substrate binding site. • AtQR possesses a conserved hydrophobic wall for stereospecific binding of substrate. • Additional Glu197 residue is critical to the high binding affinity. - Abstract: (R)-3-Quinuclidinol, a useful compound for the synthesis of various pharmaceuticals, can be enantioselectively produced from 3-quinuclidinone by 3-quinuclidinone reductase. Recently, a novel NADH-dependent 3-quinuclidionone reductase (AtQR) was isolated from Agrobacterium tumefaciens, and showed much higher substrate-binding affinity (>100 fold) than the reported 3-quinuclidionone reductase (RrQR) from Rhodotorula rubra. Here, we report the crystal structure of AtQR at 1.72 Å. Three NADH-bound protomers and one NADH-free protomer form a tetrameric structure in an asymmetric unit of crystals. NADH not only acts as a proton donor, but also contributes to the stability of the α7 helix. This helix is a unique and functionally significant part of AtQR and is related to form a deep catalytic cavity. AtQR has all three catalytic residues of the short-chain dehydrogenases/reductases family and the hydrophobic wall for the enantioselective reduction of 3-quinuclidinone as well as RrQR. An additional residue on the α7 helix, Glu197, exists near the active site of AtQR. This acidic residue is considered to form a direct interaction with the amine part of 3-quinuclidinone, which contributes to substrate orientation and enhancement of substrate-binding affinity. Mutational analyses also support that Glu197 is an indispensable residue for the activity.

ADP-ribosylation of dinitrogenase reductase in Rhodobacter capsulatus

International Nuclear Information System (INIS)

Jouanneau, Y.; Roby, C.; Meyer, C.M.; Vignais, P.M.

1989-01-01

In the photosynthetic bacterium Rhodobacter capsulatus, nitrogenase is regulated by a reversible covalent modification of Fe protein or dinitrogenase reductase (Rc2). The linkage of the modifying group to inactive Rc2 was found to be sensitive to alkali and to neutral hydroxylamine. Complete release of the modifying group was achieved by incubation of inactive Rc2 in 0.4 or 1 M hydroxylamine. After hydroxylamine treatment of the Rc2 preparation, the modifying group could be isolated and purified by affinity chromatography and ion-exchange HPLC. The modifying group comigrated with ADP-ribose on both ion-exchange HPLC and thin-layer chromatography. Analyses by 31 P NMR spectroscopy and mass spectrometry provided further evidence that the modifying group was ADP-ribose. The NMR spectrum of inactive Rc2 exhibited signals characteristic of ADP-ribose; integration of these signals allowed calculation of a molar ration ADP-ribose/Rc2 of 0.63. A hexapeptide carrying the ADP-ribose moiety was purified from a subtilisin digest of inactive Rc2. The structure of this peptide, determined by amino acid analysis and sequencing, is Gly-Arg(ADP-ribose)-Gly-Val-Ile-Thr. This structure allows identification of the binding site for ADP-ribose as Arg 101 of the polypeptide chain of Rc2. It is concluded that nitrogenase activity in R. capsulatus is regulated by reversible ADP-ribosylation of a specific arginyl residue of dinitrogenase reductase

10 CFR 850.28 - Respiratory protection.

Science.gov (United States)

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Respiratory protection. 850.28 Section 850.28 Energy... Respiratory protection. (a) The responsible employer must establish a respiratory protection program that complies with the respiratory protection program requirements of 29 CFR 1910.134, Respiratory Protection...

A genetic screen reveals a periplasmic copper chaperone required for nitrite reductase activity in pathogenic Neisseria.

Science.gov (United States)

Jen, Freda E-C; Djoko, Karrera Y; Bent, Stephen J; Day, Christopher J; McEwan, Alastair G; Jennings, Michael P

2015-09-01

Under conditions of low oxygen availability, Neisseria meningitidis and Neisseria gonorrhoeae are able to respire via a partial denitrification pathway in which nitrite is converted to nitrous oxide. In this process, nitrite reductase (AniA), a copper (Cu)-containing protein converts nitrite to NO, and this product is converted to nitrous oxide by nitric oxide reductase (NorB). NorB also confers protection against toxic NO, and so we devised a conditional lethal screen, using a norB mutant, to identify mutants that were resistant to nitrite-dependent killing. After random-deletion mutagenesis of N. meningitidis, this genetic screen identified a gene encoding a Cu chaperone that is essential for AniA function, AccA. Purified AccA binds one Cu (I) ion and also possesses a second binding site for Cu (II). This novel periplasmic Cu chaperone (AccA) appears to be essential for provision of Cu ions to AniA of pathogenic Neisseria to generate an active nitrite reductase. Apart from the Neisseria genus, AccA is distributed across a wide range of environmental Proteobacteria species. © FASEB.

Respiratory viral infections in infancy and school age respiratory outcomes and healthcare costs.

Science.gov (United States)

MacBean, Victoria; Drysdale, Simon B; Yarzi, Muska N; Peacock, Janet L; Rafferty, Gerrard F; Greenough, Anne

2018-03-01

To determine the impact of viral lower respiratory tract infections (LRTIs) in infancy including rhinovirus (RV) and infancy respiratory syncytial virus (RSV), on school age pulmonary function and healthcare utilization in prematurely born children. School age respiratory outcomes would be worse and healthcare utilization greater in children who had viral LRTIs in infancy. Prospective study. A cohort of prematurely born children who had symptomatic LRTIs during infancy documented, was recalled. Pulmonary function was assessed at 5 to 7 years of age and health related costs of care from aged one to follow-up determined. Fifty-one children, median gestational age 33 +6 weeks, were assessed at a median (IQR) age 7.03 (6.37-7.26) years. Twenty-one children had no LRTI, 14 RV LRTI, 10 RSV LRTI, and 6 another viral LRTI (other LRTI). Compared to the no LRTI group, the RV group had a lower FEV 1 (P = 0.033) and the other LRTI group a lower FVC (P = 0.006). Non-respiratory medication costs were higher in the RV (P = 0.018) and RSV (P = 0.013) groups. Overall respiratory healthcare costs in the RV (£153/year) and RSV (£27/year) groups did not differ significantly from the no LRTI group (£56/year); the other LRTI group (£431/year) had higher respiratory healthcare costs (P = 0.042). In moderately prematurely born children, RV and RSV LRTIs in infancy were not associated with higher respiratory healthcare costs after infancy. Children who experienced LRTIs caused by other respiratory viruses (including RV) had higher respiratory healthcare costs and greater pulmonary function impairment. © 2018 Wiley Periodicals, Inc.

Respiratory viruses in children hospitalized for acute lower respiratory tract infection in Ghana.

Science.gov (United States)

Kwofie, Theophilus B; Anane, Yaw A; Nkrumah, Bernard; Annan, Augustina; Nguah, Samuel B; Owusu, Michael

2012-04-10

Acute respiratory tract infections are one of the major causes of morbidity and mortality among young children in developing countries. Information on the viral aetiology of acute respiratory infections in developing countries is very limited. The study was done to identify viruses associated with acute lower respiratory tract infection among children less than 5 years. Nasopharyngeal samples and blood cultures were collected from children less than 5 years who have been hospitalized for acute lower respiratory tract infection. Viruses and bacteria were identified using Reverse Transcriptase Real-Time Polymerase Chain Reaction and conventional biochemical techniques. Out of 128 patients recruited, 33(25.88%%, 95%CI: 18.5% to 34.2%) were positive for one or more viruses. Respiratory Syncytial Virus (RSV) was detected in 18(14.1%, 95%CI: 8.5% to 21.3%) patients followed by Adenoviruses (AdV) in 13(10.2%, 95%CI: 5.5% to 16.7%), Parainfluenza (PIV type: 1, 2, 3) in 4(3.1%, 95%CI: 0.9% to 7.8%) and influenza B viruses in 1(0.8%, 95%CI: 0.0 to 4.3). Concomitant viral and bacterial co-infection occurred in two patients. There were no detectable significant differences in the clinical signs, symptoms and severity for the various pathogens isolated. A total of 61.1% (22/36) of positive viruses were detected during the rainy season and Respiratory Syncytial Virus was the most predominant. The study has demonstrated an important burden of respiratory viruses as major causes of childhood acute respiratory infection in a tertiary health institution in Ghana. The data addresses a need for more studies on viral associated respiratory tract infection.

Aldose Reductase-Deficient Mice Develop Nephrogenic Diabetes Insipidus

Science.gov (United States)

Ho, Horace T. B.; Chung, Sookja K.; Law, Janice W. S.; Ko, Ben C. B.; Tam, Sidney C. F.; Brooks, Heddwen L.; Knepper, Mark A.; Chung, Stephen S. M.

2000-01-01

Aldose reductase (ALR2) is thought to be involved in the pathogenesis of various diseases associated with diabetes mellitus, such as cataract, retinopathy, neuropathy, and nephropathy. However, its physiological functions are not well understood. We developed mice deficient in this enzyme and found that they had no apparent developmental or reproductive abnormality except that they drank and urinated significantly more than their wild-type littermates. These ALR2-deficient mice exhibited a partially defective urine-concentrating ability, having a phenotype resembling that of nephrogenic diabetes insipidus. PMID:10913167

X-ray structural studies of quinone reductase 2 nanomolar range inhibitors

Energy Technology Data Exchange (ETDEWEB)

Pegan, Scott D.; Sturdy, Megan; Ferry, Gilles; Delagrange, Philippe; Boutin, Jean A.; Mesecar, Andrew D. (IdRS); (Purdue); (Colorado); (UIC)

2011-09-06

Quinone reductase 2 (QR2) is one of two members comprising the mammalian quinone reductase family of enzymes responsible for performing FAD mediated reductions of quinone substrates. In contrast to quinone reductase 1 (QR1) which uses NAD(P)H as its co-substrate, QR2 utilizes a rare group of hydride donors, N-methyl or N-ribosyl nicotinamide. Several studies have linked QR2 to the generation of quinone free radicals, several neuronal degenerative diseases, and cancer. QR2 has been also identified as the third melatonin receptor (MT3) through in cellulo and in vitro inhibition of QR2 by traditional MT3 ligands, and through recent X-ray structures of human QR2 (hQR2) in complex with melatonin and 2-iodomelatonin. Several MT3 specific ligands have been developed that exhibit both potent in cellulo inhibition of hQR2 nanomolar, affinity for MT3. The potency of these ligands suggest their use as molecular probes for hQR2. However, no definitive correlation between traditionally obtained MT3 ligand affinity and hQR2 inhibition exists limiting our understanding of how these ligands are accommodated in the hQR2 active site. To obtain a clearer relationship between the structures of developed MT3 ligands and their inhibitory properties, in cellulo and in vitro IC{sub 50} values were determined for a representative set of MT3 ligands (MCA-NAT, 2-I-MCANAT, prazosin, S26695, S32797, and S29434). Furthermore, X-ray structures for each of these ligands in complex with hQR2 were determined allowing for a structural evaluation of the binding modes of these ligands in relation to the potency of MT3 ligands.

[Respiratory symptoms and atmospheric pollution and respiratory symptoms in the general population].

Science.gov (United States)

Simon, I; Charpin, D

2010-06-01

Epidemiological studies on air pollution have mainly been interested in the effects of short- or long-term exposure on patients suffering from respiratory illnesses. Fewer studies have addressed the acute effects of air pollution on respiratory symptoms in the general population. We conducted a review of the literature over the last 16years that has addressed the impact of atmospheric pollution on respiratory symptoms in the general population to estimate the magnitude of effect. The majority of studies demonstrated a significant association between exposure to air pollutants and the occurrence of respiratory symptoms, without any threshold. Although a link between atmospheric pollution and respiratory symptoms has been demonstrated, knowledge of the effects of specific air pollutants and the effect of pollution on particular vulnerable groups (infants, young children, the elderly) is still limited. There is a need for further studies in this area. Copyright 2010 SPLF. Published by Elsevier Masson SAS. All rights reserved.

Ebselen: A thioredoxin reductase-dependent catalyst for α-tocopherol quinone reduction

International Nuclear Information System (INIS)

Fang Jianguo; Zhong Liangwei; Zhao Rong; Holmgren, Arne

2005-01-01

The thioredoxin system, composed of thioredoxin (Trx), thioredoxin reductase (TrxR), and NADPH, is a powerful protein disulfide reductase system with a broad substrate specificity. Recently the selenazol drug ebselen was shown to be a substrate for both mammalian TrxR and Trx. We examined if α-tocopherol quinone (TQ), a product of α-tocopherol oxidation, is reduced by ebselen in the presence of TrxR, since TQ was not a substrate for the enzyme itself. Ebselen reduction of TQ in the presence of TrxR was caused by ebselen selenol, generated from fast reduction of ebselen by the enzyme. TQ has no intrinsic antioxidant activity, while the product of reduction of TQ, α-tocopherolhydroquinone (TQH 2 ), is a potent antioxidant. The thioredoxin system dependence of ebselen to catalyze reduction of other oxidized species, such as hydrogen peroxide, dehydroascorbate, and peroxynitrite, is discussed. The ability of ebselen to reduce TQ via the thioredoxin system is a novel mechanism to explain the effects of the drug as an antioxidant in vivo

Respiratory viruses in children hospitalized for acute lower respiratory tract infection in Ghana

Directory of Open Access Journals (Sweden)

Kwofie Theophilus B

2012-04-01

Full Text Available Abstract Background Acute respiratory tract infections are one of the major causes of morbidity and mortality among young children in developing countries. Information on the viral aetiology of acute respiratory infections in developing countries is very limited. The study was done to identify viruses associated with acute lower respiratory tract infection among children less than 5 years. Method Nasopharyngeal samples and blood cultures were collected from children less than 5 years who have been hospitalized for acute lower respiratory tract infection. Viruses and bacteria were identified using Reverse Transcriptase Real-Time Polymerase Chain Reaction and conventional biochemical techniques. Results Out of 128 patients recruited, 33(25.88%%, 95%CI: 18.5% to 34.2% were positive for one or more viruses. Respiratory Syncytial Virus (RSV was detected in 18(14.1%, 95%CI: 8.5% to 21.3% patients followed by Adenoviruses (AdV in 13(10.2%, 95%CI: 5.5% to 16.7%, Parainfluenza (PIV type: 1, 2, 3 in 4(3.1%, 95%CI: 0.9% to 7.8% and influenza B viruses in 1(0.8%, 95%CI: 0.0 to 4.3. Concomitant viral and bacterial co-infection occurred in two patients. There were no detectable significant differences in the clinical signs, symptoms and severity for the various pathogens isolated. A total of 61.1% (22/36 of positive viruses were detected during the rainy season and Respiratory Syncytial Virus was the most predominant. Conclusion The study has demonstrated an important burden of respiratory viruses as major causes of childhood acute respiratory infection in a tertiary health institution in Ghana. The data addresses a need for more studies on viral associated respiratory tract infection.

Protective effect of Pterocarpus marsupium bark extracts against cataract through the inhibition of aldose reductase activity in streptozotocin-induced diabetic male albino rats.

Science.gov (United States)

Xu, YanLi; Zhao, Yongxia; Sui, YaNan; Lei, XiaoJun

2018-04-01

The present study was aimed to investigate the protective effect of Pterocarpus marsupium bark extracts against cataract in streptozotocin-induced diabetic male albino rats. Aldose reductase is a key enzyme in the intracellular polyol pathway, which plays a major role in the development of diabetic cataract. Rats were divided into five groups as normal control, diabetic control, and diabetic control treated with different concentrations of Pterocarpus marsupium bark extracts. Presence of major constituents in Pterocarpus marsupium bark extract was performed by qualitative analysis. Body weight changes, blood glucose, blood insulin, and reduced glutathione (GSH) and aldose reductase mRNA and protein expression were determined. Rat body weight gain was noted following treatment with bark extracts. The blood glucose was reduced up to 36% following treatment with bark extracts. The blood insulin and tissue GSH contents were substantially increased more than 100% in diabetic rats following treatment with extracts. Aldose reductase activity was reduced up to 79.3% in diabetic rats following treatment with extracts. V max , K m , and K i of aldose reductase were reduced in the lens tissue homogenate compared to the diabetic control. Aldose reductase mRNA and protein expression were reduced more than 50% following treatment with extracts. Treatment with Pterocarpus marsupium bark was able to normalize these levels. Taking all these data together, it is concluded that the use of Pterocarpus marsupium bark extracts could be the potential therapeutic approach for the reduction of aldose reductase against diabetic cataract.

Evaluation of the Usefulness of the Respiratory Guidance System in the Respiratory Gating Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Lee, Yeong Cheol; Kim, Sun Myung; Do, Gyeong Min; Park, Geun Yong; Kim, Gun Oh; Kim, Young Bum [Dept. of Radiation Oncology, Guro Hospital, Korea Univeristy, Seoul (Korea, Republic of)

2012-09-15

The respiration is one of the most important factors in respiratory gating radiation therapy (RGRT). We have developed an unique respiratory guidance system using an audio-visual system in order to support and stabilize individual patient's respiration and evaluated the usefulness of this system. Seven patients received the RGRT at our clinic from June 2011 to April 2012. After breathing exercise standard deviations by the superficial contents of respiratory cycles and functions, and analyzed them to examine changes in their breathing before and with the audio-visual system, we measured their spontaneous respiration and their respiration with the audio-visual system respectively. With the measured data, we yielded after the therapy. The PTP (peak to peak) of the standard deviations of the free breathing, the audio guidance system, and the respiratory guidance system were 0.343, 0.148, and 0.078 respectively. The respiratory cycles were 0.645, 0.345, and 0.171 respectively and the superficial contents of the respiratory functions were 2.591, 1.008, and 0.877 respectively. The average values of the differences in the standard deviations among the whole patients at the CT room and therapy room were 0.425 for the PTP, 1.566 for the respiratory cycles, and 3.671 for the respiratory superficial contents. As for the standard deviations before and after the application of the PTP respiratory guidance system, that of the PTP was 0.265, that of the respiratory cycles was 0.474, and that of the respiratory superficial contents. The results of t-test of the values before and after free breathing and the audio-visual guidance system showed that the P-value of the PTP was 0.035, that of the cycles 0.009, and that of the respiratory superficial contents 0.010. The respiratory control could be one of the most important factors in the RGRT which determines the success or failure of a treatment. We were able to get more stable breathing with the audio-visual respiratory

Evaluation of the Usefulness of the Respiratory Guidance System in the Respiratory Gating Radiation Therapy

International Nuclear Information System (INIS)

Lee, Yeong Cheol; Kim, Sun Myung; Do, Gyeong Min; Park, Geun Yong; Kim, Gun Oh; Kim, Young Bum

2012-01-01

The respiration is one of the most important factors in respiratory gating radiation therapy (RGRT). We have developed an unique respiratory guidance system using an audio-visual system in order to support and stabilize individual patient's respiration and evaluated the usefulness of this system. Seven patients received the RGRT at our clinic from June 2011 to April 2012. After breathing exercise standard deviations by the superficial contents of respiratory cycles and functions, and analyzed them to examine changes in their breathing before and with the audio-visual system, we measured their spontaneous respiration and their respiration with the audio-visual system respectively. With the measured data, we yielded after the therapy. The PTP (peak to peak) of the standard deviations of the free breathing, the audio guidance system, and the respiratory guidance system were 0.343, 0.148, and 0.078 respectively. The respiratory cycles were 0.645, 0.345, and 0.171 respectively and the superficial contents of the respiratory functions were 2.591, 1.008, and 0.877 respectively. The average values of the differences in the standard deviations among the whole patients at the CT room and therapy room were 0.425 for the PTP, 1.566 for the respiratory cycles, and 3.671 for the respiratory superficial contents. As for the standard deviations before and after the application of the PTP respiratory guidance system, that of the PTP was 0.265, that of the respiratory cycles was 0.474, and that of the respiratory superficial contents. The results of t-test of the values before and after free breathing and the audio-visual guidance system showed that the P-value of the PTP was 0.035, that of the cycles 0.009, and that of the respiratory superficial contents 0.010. The respiratory control could be one of the most important factors in the RGRT which determines the success or failure of a treatment. We were able to get more stable breathing with the audio-visual respiratory guidance

Evaluation of leachate quality from pentachlorophenol, creosote and ACA [ammoniacal chromium arsenate] preserved wood products

International Nuclear Information System (INIS)

Whiticar, D.M.; Letourneau, L.; Konasewich, D.

1994-01-01

A field study was conducted to evaluate the leachability characteristics of pentachlorophenol (PCP), creosote, and ammoniacal chromium arsenate (ACA) wood preservatives from freshly treated wood products. Test products included PCP-treated utility poles, creosote-treated timbers and marine pilings, and ACA-treated utility poles. Bundles of test products were placed over collection trays to collect the leachate generated by natural rainfall and by sprinkling with tap water. The sampling schedule was based on accumulated rainfall with samples taken at about every 15 mm from 15 mm to 150 mm. Analyses included pH, oil and grease, total organic carbon, ammonia, metals, polynuclear aromatic hydrocarbons (PAH), chlorinated and nonchlorinated phenols, resin acids, and fish toxicity. The study indicated that leachates from wood products freshly treated with ACA, creosote, and PCP have potential for aquatic toxicity if released to the environment. A decreasing trend was noted in both the arsenic and copper releases as cumulative precipitation increased. PCP releases remained constant over the course of the study while PAH releases showed no significant trend. Phenanthrene was found to be the main component in the releases. 28 refs., 18 figs., 7 tabs

Microbicidal activity of neutrophils is inhibited by isolates from recurrent vaginal candidiasis (RVVC) caused by Candida albicans through fungal thioredoxin reductase.

Science.gov (United States)

Ratti, Bianca Altrão; Godoy, Janine Silva Ribeiro; de Souza Bonfim Mendonça, Patrícia; Bidóia, Danielle Lazarin; Nakamura, Tânia Ueda; Nakamura, Celso Vataru; Lopes Consolaro, Marcia Edilaine; Estivalet Svidzinski, Terezinha Inez; de Oliveira Silva, Sueli

2015-01-01

Vulvovaginal candidiasis (VVC) is characterized by an infection of the vulva and vagina, mainly caused by Candida albicans, a commensal microorganism that inhabits the vaginal, digestive, and respiratory mucosae. Vulvovaginal candidiasis affects approximately 75% of women, and 5% develop the recurrent form (RVVC). The aim of the present study was to evaluate whether neutrophils microbicidal response is triggered when activated with RVVC isolates caused by C. albicans. Our results showed that RVVC isolates induced neutrophil migration but significantly decrease the microbicidal activity of neutrophils, compared with VVC and ASS isolates. The microbicidal activity of neutrophils is highly dependent on the production of reactive oxygen species/reactive nitrogen species (ROS/RNS). However, this isolate induced detoxification of ROS/RNS produced by neutrophils, reflected by the high level of thiol groups and by the oxygen consumption. Therefore, RVVC isolates induced biochemical changes in the inflammatory response triggered by neutrophils, and these effects were mainly related to the detoxification of ROS/RNS through the thioredoxin reductase (TR), a key antioxidant enzyme in fungi. This might be one of the resistance mechanisms triggered by RVVC caused by C. albicans. Copyright © 2014 Elsevier Inc. All rights reserved.

Ocular Tropism of Respiratory Viruses

Science.gov (United States)

Rota, Paul A.; Tumpey, Terrence M.

2013-01-01

SUMMARY Respiratory viruses (including adenovirus, influenza virus, respiratory syncytial virus, coronavirus, and rhinovirus) cause a broad spectrum of disease in humans, ranging from mild influenza-like symptoms to acute respiratory failure. While species D adenoviruses and subtype H7 influenza viruses are known to possess an ocular tropism, documented human ocular disease has been reported following infection with all principal respiratory viruses. In this review, we describe the anatomical proximity and cellular receptor distribution between ocular and respiratory tissues. All major respiratory viruses and their association with human ocular disease are discussed. Research utilizing in vitro and in vivo models to study the ability of respiratory viruses to use the eye as a portal of entry as well as a primary site of virus replication is highlighted. Identification of shared receptor-binding preferences, host responses, and laboratory modeling protocols among these viruses provides a needed bridge between clinical and laboratory studies of virus tropism. PMID:23471620

NADPH-dependent D-aldose reductases and xylose fermentation in Fusarium oxysporum

DEFF Research Database (Denmark)

Panagiotou, Gianni; Christakopoulos, P.

2004-01-01

Two aldose (xylose) reductases (ARI and ARII) from Fusarium oxysporum were purified and characterized. The native ARI was a monomer with M-r 41000, pI 5.2 and showed a 52-fold preference for NADPH over NADH, while ARII was homodimeric with a subunit of M-r 37000, pI 3.6 and a 60-fold preference...

Influence of acute and chronic administration of methadone hydrochloride on NADPH-cytochrome c reductase and cytochrome P-450 of mouse liver microsomes.

Science.gov (United States)

Datta, R K; Johnson, E A; Bhattacharjee, G; Stenger, R J

1976-03-01

Administration of a single acute dose (20 mg/kg body weight) of methadone hydrochloride to both male and female mice increased the specific activity of NADPH-cytochrome c reductase and did not change much the content of cytochrome P-450 of their liver microsomes. Administration of multiple acute doses of methadone in male mice increased the specific activity of cytochrome c reductase and the content of cytochrome P-450 of their liver microsomes. Chronic administration of progressively increasing doses of methadone (up to 40 mg/kg body weight) to male mice increased the specific activity of c reductase. Similar chronic administration of methadone up to 28 mg/kg body weight also increased the microsomal content of P-450, but with higher doses of methadone, the content of P-450 declined and finally dropped slightly below control levels. The levels of c reductase activity and P-450 content returned to normal about two weeks after discontinuation of methadone administration.

Unexpected ethical dilemmas in sex assignment in 46,XY DSD due to 5-alpha reductase type 2 deficiency.

Science.gov (United States)

Byers, Heather M; Mohnach, Lauren H; Fechner, Patricia Y; Chen, Ming; Thomas, Inas H; Ramsdell, Linda A; Shnorhavorian, Margarett; McCauley, Elizabeth A; Amies Oelschlager, Anne-Marie E; Park, John M; Sandberg, David E; Adam, Margaret P; Keegan, Catherine E

2017-06-01

Sex assignment at birth remains one of the most clinically challenging and controversial topics in 46,XY disorders of sexual development (DSD). This is particularly challenging in deficiency of 5-alpha reductase type 2 given that external genitalia are typically undervirilized at birth but typically virilize at puberty to a variable degree. Historically, most individuals with 5-alpha reductase deficiency were raised females. However, reports that over half of patients who underwent a virilizing puberty adopted an adult male gender identity have challenged this practice. Consensus guidelines on assignment of sex of rearing at birth are equivocal or favor male assignment in the most virilized cases. While a male sex of rearing assignment may avoid lifelong hormonal therapy and/or allow the potential for fertility, female sex assignment may be more consistent with external anatomy in the most severely undervirilized cases. Herein, we describe five patients with 46,XY DSD due 5-alpha-reductase type 2 deficiency, all with a severe phenotype. An inter-disciplinary DSD medical team at one of two academic centers evaluated each patient. This case series illustrates the complicated decision-making process of assignment of sex of rearing at birth in 5-alpha reductase type 2 deficiency and the challenges that arise when the interests of the child, parental wishes, recommendations of the medical team, and state law collide. © 2017 Wiley Periodicals, Inc.

Determination of chromated copper arsenate (CCA) in treated wood of Eucalyptus

Energy Technology Data Exchange (ETDEWEB)

Parreira, Paulo S., E-mail: parreira@uel.b [Universidade Estadual de Londrina (UEL), PR (Brazil). Dept. de Fisica. Lab.de Fisica Nuclear Aplicada; Vendrametto, Guilherme R.; Cunha, Magda E.T., E-mail: grvendrametto@gmail.co [Universidade Norte do Parana, Arapongas, PR (Brazil). Centro de Ciencias Humanas, da Saude, Exatas e Tecnologicas-A

2009-07-01

This work deals with the possible application of a portable energy dispersive handmade system (PXRF-LFNA-02) for the determination of Chromium, Copper and Arsenic in the preservative solution used to protect commercial wood of Eucalyptus, which are employed as wood fence, posts, contention fences, railroad sleepers, etc. It was prepared five body-of-proof made of eucalyptus alburnum with different concentrations for each element varying from 0.0061 to 0.0180 (g/g) for CrO{sub 3}, 0.0024 to 0.0070 (g/g) for CuO and 0.0044 to 0.0129 (g/g) for As{sub 2}O{sub 5}. Four of them were used for calibration curves and one used as reference sample. It was used a commercial CCA (Chromated Copper Arsenate ) solution to prepare the samples. The results show a good linear regression between concentrations and X-rays intensities, after applied the multiple linear regression methodology for interelemental corrections. The values obtained with this methodology were 3.01(kg/m{sup 3}), 1.18 (kg/m{sup 3}) e 2.21 (kg/m{sup 3}) for CrO{sub 3}, CuO and As{sub 2}O{sub 5}, respectively, while the nominal values are 2.90 (kg/m{sup 3}) for CrO{sub 3}, 1.13 (kg/m{sup 3}) for CuO and 2.07 (kg/m{sup 3}) for As{sub 2}O{sub 5}. The ED-XRF (Energy Dispersive X-Rays Fluorescence) is a well established technique with high-speed of analytical procedure and its portable configuration allowing a multielemental, simultaneous and non destructive analyses besides in situ application. (author)

RESPIRATORY GYMNASTICS AS A REHABILITATION MEANS FOR THE PRESCHOOL CHILDREN WITH THE RESPIRATORY PATHOLOGY

Directory of Open Access Journals (Sweden)

T.A. Shemyakina

2007-01-01

Full Text Available The researchers analyzed the efficacy of the new medical technology aimed at rehabilitation of the preschool children with the respiratory pathology. 177 children aged between 2 and 7 with recurrent respiratory diseases, bronchial asthma or chronic pathology of the end organs have been examined for 9 months. It was uncovered that among children (n = 90, who performed the sets of the therapeutic physical training and respiratory gymnastics according to the methods developed by the authors, the recurrence of the acute respiratory diseases and exacerbations of bronchial asthma was lower by 1,83 and 1,86 timers respectively. Besides, among children of this group the researchers noted the significant improvement of the physical qualities, spirometric indices and cytological picture of the substance removed from the nasal cavity if compared with the children from the screening group (n = 87, who performed the sets of the conventional gymnastics at the physical training lessons. Thus, the researchers proved the high efficacy of the proposed technology for the rehabilitation of the children, suffering from the chronic respiratory pathology.Key words: acute respiratory diseases, asthma, therapeutic physical training, respiratory gymnastics, children.

Variation and inheritance of iron reductase activity in the roots of common bean (Phaseolus vulgaris L.) and association with seed iron accumulation QTL.

Science.gov (United States)

Blair, Matthew W; Knewtson, Sharon Jb; Astudillo, Carolina; Li, Chee-Ming; Fernandez, Andrea C; Grusak, Michael A

2010-10-05

Iron deficiency anemia is a global problem which often affects women and children of developing countries. Strategy I plants, such as common bean (Phaseolus vulgaris L.) take up iron through a process that involves an iron reduction mechanism in their roots; this reduction is required to convert ferric iron to ferrous iron. Root absorbed iron is critical for the iron nutrition of the plant, and for the delivery of iron to the shoot and ultimately the seeds. The objectives of this study were to determine the variability and inheritance for iron reductase activity in a range of genotypes and in a low × high seed iron cross (DOR364 x G19833), to identify quantitative trait loci (QTL) for this trait, and to assess possible associations with seed iron levels. The experiments were carried out with hydroponically grown plants provided different amounts of iron varying between 0 and 20 μM Fe(III)-EDDHA. The parents, DOR364 and G19833, plus 13 other cultivated or wild beans, were found to differ in iron reductase activity. Based on these initial experiments, two growth conditions (iron limited and iron sufficient) were selected as treatments for evaluating the DOR364 × G19833 recombinant inbred lines. A single major QTL was found for iron reductase activity under iron-limited conditions (1 μM Fe) on linkage group b02 and another major QTL was found under iron sufficient conditions (15 μM Fe) on linkage group b11. Associations between the b11 QTL were found with several QTL for seed iron. Genes conditioning iron reductase activity in iron sufficient bean plants appear to be associated with genes contributing to seed iron accumulation. Markers for bean iron reductase (FRO) homologues were found with in silico mapping based on common bean synteny with soybean and Medicago truncatula on b06 and b07; however, neither locus aligned with the QTL for iron reductase activity. In summary, the QTL for iron reductase activity under iron limited conditions may be useful in

Variation and inheritance of iron reductase activity in the roots of common bean (Phaseolus vulgaris L. and association with seed iron accumulation QTL

Directory of Open Access Journals (Sweden)

Fernandez Andrea C

2010-10-01

Full Text Available Abstract Background Iron deficiency anemia is a global problem which often affects women and children of developing countries. Strategy I plants, such as common bean (Phaseolus vulgaris L. take up iron through a process that involves an iron reduction mechanism in their roots; this reduction is required to convert ferric iron to ferrous iron. Root absorbed iron is critical for the iron nutrition of the plant, and for the delivery of iron to the shoot and ultimately the seeds. The objectives of this study were to determine the variability and inheritance for iron reductase activity in a range of genotypes and in a low × high seed iron cross (DOR364 × G19833, to identify quantitative trait loci (QTL for this trait, and to assess possible associations with seed iron levels. Results The experiments were carried out with hydroponically grown plants provided different amounts of iron varying between 0 and 20 μM Fe(III-EDDHA. The parents, DOR364 and G19833, plus 13 other cultivated or wild beans, were found to differ in iron reductase activity. Based on these initial experiments, two growth conditions (iron limited and iron sufficient were selected as treatments for evaluating the DOR364 × G19833 recombinant inbred lines. A single major QTL was found for iron reductase activity under iron-limited conditions (1 μM Fe on linkage group b02 and another major QTL was found under iron sufficient conditions (15 μM Fe on linkage group b11. Associations between the b11 QTL were found with several QTL for seed iron. Conclusions Genes conditioning iron reductase activity in iron sufficient bean plants appear to be associated with genes contributing to seed iron accumulation. Markers for bean iron reductase (FRO homologues were found with in silico mapping based on common bean synteny with soybean and Medicago truncatula on b06 and b07; however, neither locus aligned with the QTL for iron reductase activity. In summary, the QTL for iron reductase activity

Respiratory muscle involvement in sarcoidosis.

Science.gov (United States)

Schreiber, Tina; Windisch, Wolfram

2018-07-01

In sarcoidosis, muscle involvement is common, but mostly asymptomatic. Currently, little is known about respiratory muscle and diaphragm involvement and function in patients with sarcoidosis. Reduced inspiratory muscle strength and/or a reduced diaphragm function may contribute to exertional dyspnea, fatigue and reduced health-related quality of life. Previous studies using volitional and non-volitional tests demonstrated a reduced inspiratory muscle strength in sarcoidosis compared to control subjects, and also showed that respiratory muscle function may even be significantly impaired in a subset of patients. Areas covered: This review examines the evidence on respiratory muscle involvement and its implications in sarcoidosis with emphasis on pathogenesis, diagnosis and treatment of respiratory muscle dysfunction. The presented evidence was identified by a literature search performed in PubMed and Medline for articles about respiratory and skeletal muscle function in sarcoidosis through to January 2018. Expert commentary: Respiratory muscle involvement in sarcoidosis is an underdiagnosed condition, which may have an important impact on dyspnea and health-related quality of life. Further studies are needed to understand the etiology, pathogenesis and extent of respiratory muscle involvement in sarcoidosis.

Fatty acyl-CoA reductases of birds

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Hellenbrand Janine

2011-12-01

Full Text Available Abstract Background Birds clean and lubricate their feathers with waxes that are produced in the uropygial gland, a holocrine gland located on their back above the tail. The type and the composition of the secreted wax esters are dependent on the bird species, for instance the wax ester secretion of goose contains branched-chain fatty acids and unbranched fatty alcohols, whereas that of barn owl contains fatty acids and alcohols both of which are branched. Alcohol-forming fatty acyl-CoA reductases (FAR catalyze the reduction of activated acyl groups to fatty alcohols that can be esterified with acyl-CoA thioesters forming wax esters. Results cDNA sequences encoding fatty acyl-CoA reductases were cloned from the uropygial glands of barn owl (Tyto alba, domestic chicken (Gallus gallus domesticus and domestic goose (Anser anser domesticus. Heterologous expression in Saccharomyces cerevisiae showed that they encode membrane associated enzymes which catalyze a NADPH dependent reduction of acyl-CoA thioesters to fatty alcohols. By feeding studies of transgenic yeast cultures and in vitro enzyme assays with membrane fractions of transgenic yeast cells two groups of isozymes with different properties were identified, termed FAR1 and FAR2. The FAR1 group mainly synthesized 1-hexadecanol and accepted substrates in the range between 14 and 18 carbon atoms, whereas the FAR2 group preferred stearoyl-CoA and accepted substrates between 16 and 20 carbon atoms. Expression studies with tissues of domestic chicken indicated that FAR transcripts were not restricted to the uropygial gland. Conclusion The data of our study suggest that the identified and characterized avian FAR isozymes, FAR1 and FAR2, can be involved in wax ester biosynthesis and in other pathways like ether lipid synthesis.

Fatty acyl-CoA reductases of birds

Science.gov (United States)

2011-01-01

Background Birds clean and lubricate their feathers with waxes that are produced in the uropygial gland, a holocrine gland located on their back above the tail. The type and the composition of the secreted wax esters are dependent on the bird species, for instance the wax ester secretion of goose contains branched-chain fatty acids and unbranched fatty alcohols, whereas that of barn owl contains fatty acids and alcohols both of which are branched. Alcohol-forming fatty acyl-CoA reductases (FAR) catalyze the reduction of activated acyl groups to fatty alcohols that can be esterified with acyl-CoA thioesters forming wax esters. Results cDNA sequences encoding fatty acyl-CoA reductases were cloned from the uropygial glands of barn owl (Tyto alba), domestic chicken (Gallus gallus domesticus) and domestic goose (Anser anser domesticus). Heterologous expression in Saccharomyces cerevisiae showed that they encode membrane associated enzymes which catalyze a NADPH dependent reduction of acyl-CoA thioesters to fatty alcohols. By feeding studies of transgenic yeast cultures and in vitro enzyme assays with membrane fractions of transgenic yeast cells two groups of isozymes with different properties were identified, termed FAR1 and FAR2. The FAR1 group mainly synthesized 1-hexadecanol and accepted substrates in the range between 14 and 18 carbon atoms, whereas the FAR2 group preferred stearoyl-CoA and accepted substrates between 16 and 20 carbon atoms. Expression studies with tissues of domestic chicken indicated that FAR transcripts were not restricted to the uropygial gland. Conclusion The data of our study suggest that the identified and characterized avian FAR isozymes, FAR1 and FAR2, can be involved in wax ester biosynthesis and in other pathways like ether lipid synthesis. PMID:22151413

Use of 5-alpha-reductase inhibitors did not increase the risk of cardiovascular diseases in patients with benign prostate hyperplasia: a five-year follow-up study.

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Teng-Fu Hsieh

Full Text Available This nationwide population-based study investigated the risk of cardiovascular diseases after 5-alpha-reductase inhibitor therapy for benign prostate hyperplasia (BPH using the National Health Insurance Research Database (NHIRD in Taiwan.In total, 1,486 adult patients newly diagnosed with BPH and who used 5-alpha-reductase inhibitors were recruited as the study cohort, along with 9,995 subjects who did not use 5-alpha-reductase inhibitors as a comparison cohort from 2003 to 2008. Each patient was monitored for 5 years, and those who subsequently had cardiovascular diseases were identified. A Cox proportional hazards model was used to compare the risk of cardiovascular diseases between the study and comparison cohorts after adjusting for possible confounding risk factors.The patients who received 5-alpha-reductase inhibitor therapy had a lower cumulative rate of cardiovascular diseases than those who did not receive 5-alpha-reductase inhibitor therapy during the 5-year follow-up period (8.4% vs. 11.2%, P=0.003. In subgroup analysis, the 5-year cardiovascular event hazard ratio (HR was lower among the patients older than 65 years with 91 to 365 cumulative defined daily dose (cDDD 5-alpha-reductase inhibitor use (HR=0.63, 95% confidence interval (CI 0.42 to 0.92; P=0.018, however there was no difference among the patients with 28 to 90 and more than 365 cDDD 5-alpha-reductase inhibitor use (HR=1.14, 95% CI 0.77 to 1.68; P=0.518 and HR=0.83, 95% CI 0.57 to 1.20; P=0.310, respectively.5-alpha-reductase inhibitor therapy did not increase the risk of cardiovascular events in the BPH patients in 5 years of follow-up. Further mechanistic research is needed.

Crystallization and preliminary crystallographic analysis of selenomethionine-labelled progesterone 5β-reductase from Digitalis lanata Ehrh

Energy Technology Data Exchange (ETDEWEB)

Egerer-Sieber, Claudia [Lehrstuhl für Biotechnik, Institut für Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 91, D-91052 Erlangen (Germany); Herl, Vanessa; Müller-Uri, Frieder; Kreis, Wolfgang [Lehrstuhl für Pharmazeutische Biologie, Institut für Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen (Germany); Muller, Yves A., E-mail: ymuller@biologie.uni-erlangen.de [Lehrstuhl für Biotechnik, Institut für Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 91, D-91052 Erlangen (Germany)

2006-03-01

Progesterone 5β-reductase is the first stereospecific enzyme in the pathway for the synthesis of cardenolides. To elucidate the structural mechanism of this reaction, we crystallized the selenomethionine-labelled enzyme from D. lanata and report the preliminary analysis of a MAD data set collected from these crystals. Progesterone 5β-reductase (5β-POR) catalyzes the reduction of progesterone to 5β-pregnane-3,20-dione and is the first stereospecific enzyme in the putative biosynthetic pathway of Digitalis cardenolides. Selenomethionine-derivatized 5β-POR from D. lanata was successfully overproduced and crystallized. The crystals belong to space group P4{sub 3}2{sub 1}2, with unit-cell parameters a = 71.73, c = 186.64 Å. A MAD data set collected at 2.7 Å resolution allowed the identification of six out of eight possible Se-atom positions. A first inspection of the MAD-phased electron-density map shows that 5β-POR is a Rossmann-type reductase and the quality of the map is such that it is anticipated that a complete atomic model of 5β-POR will readily be built.

Brevetoxin-2, is a unique inhibitor of the C-terminal redox center of mammalian thioredoxin reductase-1.

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Chen, Wei; Tuladhar, Anupama; Rolle, Shantelle; Lai, Yanhao; Rodriguez Del Rey, Freddy; Zavala, Cristian E; Liu, Yuan; Rein, Kathleen S

2017-08-15

Karenia brevis, the Florida red tide dinoflagellate produces a suite of neurotoxins known as the brevetoxins. The most abundant of the brevetoxins PbTx-2, was found to inhibit the thioredoxin-thioredoxin reductase system, whereas the PbTx-3 has no effect on this system. On the other hand, PbTx-2 activates the reduction of small disulfides such as 5,5'-dithio-bis-(2-nitrobenzoic acid) by thioredoxin reductase. PbTx-2 has an α, β-unsaturated aldehyde moiety which functions as an efficient electrophile and selenocysteine conjugates are readily formed. PbTx-2 blocks the inhibition of TrxR by the inhibitor curcumin, whereas curcumin blocks PbTx-2 activation of TrxR. It is proposed that the mechanism of inhibition of thioredoxin reduction is via the formation of a Michael adduct between selenocysteine and the α, β-unsaturated aldehyde moiety of PbTx-2. PbTx-2 had no effect on the rates of reactions catalyzed by related enzymes such as glutathione reductase, glutathione peroxidase or glutaredoxin. Copyright © 2017 Elsevier Inc. All rights reserved.

The 5 Alpha-Reductase Isozyme Family: A Review of Basic Biology and Their Role in Human Diseases

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Faris Azzouni

2012-01-01

Full Text Available Despite the discovery of 5 alpha-reduction as an enzymatic step in steroid metabolism in 1951, and the discovery that dihydrotestosterone is more potent than testosterone in 1968, the significance of 5 alpha-reduced steroids in human diseases was not appreciated until the discovery of 5 alpha-reductase type 2 deficiency in 1974. Affected males are born with ambiguous external genitalia, despite normal internal genitalia. The prostate is hypoplastic, nonpalpable on rectal examination and approximately 1/10th the size of age-matched normal glands. Benign prostate hyperplasia or prostate cancer does not develop in these patients. At puberty, the external genitalia virilize partially, however, secondary sexual hair remains sparse and male pattern baldness and acne develop rarely. Several compounds have been developed to inhibit the 5 alpha-reductase isozymes and they play an important role in the prevention and treatment of many common diseases. This review describes the basic biochemical properties, functions, tissue distribution, chromosomal location, and clinical significance of the 5 alpha-reductase isozyme family.

Taxonomically-linked growth phenotypes during arsenic stress among arsenic resistant bacteria isolated from soils overlying the Centralia coal seam fire.

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Dunivin, Taylor K; Miller, Justine; Shade, Ashley

2018-01-01

Arsenic (As), a toxic element, has impacted life since early Earth. Thus, microorganisms have evolved many As resistance and tolerance mechanisms to improve their survival outcomes given As exposure. We isolated As resistant bacteria from Centralia, PA, the site of an underground coal seam fire that has been burning since 1962. From a 57.4°C soil collected from a vent above the fire, we isolated 25 unique aerobic As resistant bacterial strains spanning seven genera. We examined their diversity, resistance gene content, transformation abilities, inhibitory concentrations, and growth phenotypes. Although As concentrations were low at the time of soil collection (2.58 ppm), isolates had high minimum inhibitory concentrations (MICs) of arsenate and arsenite (>300 mM and 20 mM respectively), and most isolates were capable of arsenate reduction. We screened isolates (PCR and sequencing) using 12 published primer sets for six As resistance genes (AsRGs). Genes encoding arsenate reductase (arsC) and arsenite efflux pumps (arsB, ACR3(2)) were present, and phylogenetic incongruence between 16S rRNA genes and AsRGs provided evidence for horizontal gene transfer. A detailed investigation of differences in isolate growth phenotypes across As concentrations (lag time to exponential growth, maximum growth rate, and maximum OD590) showed a relationship with taxonomy, providing information that could help to predict an isolate's performance given As exposure in situ. Our results suggest that microbiological management and remediation of environmental As could be informed by taxonomically-linked As tolerance, potential for resistance gene transferability, and the rare biosphere.

Dysrhythmias of the respiratory oscillator

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Paydarfar, David; Buerkel, Daniel M.

1995-03-01

Breathing is regulated by a central neural oscillator that produces rhythmic output to the respiratory muscles. Pathological disturbances in rhythm (dysrhythmias) are observed in the breathing pattern of children and adults with neurological and cardiopulmonary diseases. The mechanisms responsible for genesis of respiratory dysrhythmias are poorly understood. The present studies take a novel approach to this problem. The basic postulate is that the rhythm of the respiratory oscillator can be altered by a variety of stimuli. When the oscillator recovers its rhythm after such perturbations, its phase may be reset relative to the original rhythm. The amount of phase resetting is dependent upon stimulus parameters and the level of respiratory drive. The long-range hypothesis is that respiratory dysrhythmias can be induced by stimuli that impinge upon or arise within the respiratory oscillator with certain combinations of strength and timing relative to the respiratory cycle. Animal studies were performed in anesthetized or decerebrate preparations. Neural respiratory rhythmicity is represented by phrenic nerve activity, allowing use of open-loop experimental conditions which avoid negative chemical feedback associated with changes in ventilation. In animal experiments, respiratory dysrhythmias can be induced by stimuli having specific combinations of strength and timing. Newborn animals readily exhibit spontaneous dysrhythmias which become more prominent at lower respiratory drives. In human subjects, swallowing was studied as a physiological perturbation of respiratory rhythm, causing a pattern of phase resetting that is characterized topologically as type 0. Computational studies of the Bonhoeffer-van der Pol (BvP) equations, whose qualitative behavior is representative of many excitable systems, supports a unified interpretation of these experimental findings. Rhythmicity is observed when the BvP model exhibits recurrent periods of excitation alternating with

Crystallization and preliminary characterization of dihydropteridine reductase from Dictyostelium discoideum

International Nuclear Information System (INIS)

Chen, Cong; Seo, Kyung Hye; Kim, Hye Lim; Zhuang, Ningning; Park, Young Shik; Lee, Kon Ho

2008-01-01

The dihydropteridine reductase from D. discoideum has been crystallized. Diffraction data were collected from a rectangular-shaped crystal to 2.16 Å resolution. Dihydropteridine reductase from Dictyostelium discoideum (dicDHPR) can produce d-threo-BH 4 [6R-(1′R,2′R)-5,6,7,8-tetrahydrobiopterin], a stereoisomer of l-erythro-BH 4 , in the last step of tetrahydrobiopterin (BH 4 ) recycling. In this reaction, DHPR uses NADH as a cofactor to reduce quinonoid dihydrobiopterin back to BH 4 . To date, the enzyme has been purified to homogeneity from many sources. In this report, the dicDHPR–NAD complex has been crystallized using the hanging-drop vapour-diffusion method with PEG 3350 as a precipitant. Rectangular-shaped crystals were obtained. Crystals grew to maximum dimensions of 0.4 × 0.6 × 0.1 mm. The crystal belonged to space group P2 1 , with unit-cell parameters a = 49.81, b = 129.90, c = 78.76 Å, β = 100.00°, and contained four molecules in the asymmetric unit, forming two closely interacting dicDHPR–NAD dimers. Diffraction data were collected to 2.16 Å resolution using synchrotron radiation. The crystal structure has been determined using the molecular-replacement method

Inhibition of thioredoxin reductase but not of glutathione reductase by the major classes of alkylating and platinum-containing anticancer compounds.

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Witte, Anne-Barbara; Anestål, Karin; Jerremalm, Elin; Ehrsson, Hans; Arnér, Elias S J

2005-09-01

Mammalian thioredoxin reductase (TrxR) is important for cell proliferation, antioxidant defense, and redox signaling. Together with glutathione reductase (GR) it is the main enzyme providing reducing equivalents to many cellular processes. GR and TrxR are flavoproteins of the same enzyme family, but only the latter is a selenoprotein. With the active site containing selenocysteine, TrxR may catalyze reduction of a wide range of substrates, but can at the same time easily be targeted by electrophilic compounds due to the extraordinarily high reactivity of a selenolate moiety. Here we addressed the inhibition of the enzyme by major anticancer alkylating agents and platinum-containing compounds and we compared it to that of GR. We confirmed prior studies suggesting that the nitrosourea carmustine can inhibit both GR and TrxR. We next found, however, that nitrogen mustards (chlorambucil and melphalan) and alkyl sulfonates (busulfan) efficiently inhibited TrxR while these compounds, surprisingly, did not inhibit GR. Inhibitions were concentration and time dependent and apparently irreversible. Anticancer anthracyclines (daunorubicin and doxorubicin) were, in contrast to the alkylating agents, not inhibitors but poor substrates of TrxR. We also found that TrxR, but not GR, was efficiently inhibited by both cisplatin, its monohydrated complex, and oxaliplatin. Carboplatin, in contrast, could not inhibit any of the two enzymes. These findings lead us to conclude that representative compounds of the major classes of clinically used anticancer alkylating agents and most platinum compounds may easily target TrxR, but not GR. The TrxR inhibition should thereby be considered as a factor that may contribute to the cytotoxicity seen upon clinical use of these drugs.

Respiratory effort from the photoplethysmogram.

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Addison, Paul S

2017-03-01

The potential for a simple, non-invasive measure of respiratory effort based on the pulse oximeter signal - the photoplethysmogram or 'pleth' - was investigated in a pilot study. Several parameters were developed based on a variety of manifestations of respiratory effort in the signal, including modulation changes in amplitude, baseline, frequency and pulse transit times, as well as distinct baseline signal shifts. Thirteen candidate parameters were investigated using data from healthy volunteers. Each volunteer underwent a series of controlled respiratory effort maneuvers at various set flow resistances and respiratory rates. Six oximeter probes were tested at various body sites. In all, over three thousand pleth-based effort-airway pressure (EP) curves were generated across the various airway constrictions, respiratory efforts, respiratory rates, subjects, probe sites, and the candidate parameters considered. Regression analysis was performed to determine the existence of positive monotonic relationships between the respiratory effort parameters and resulting airway pressures. Six of the candidate parameters investigated exhibited a distinct positive relationship (poximeter probe and an ECG (P2E-Effort) and the other using two pulse oximeter probes placed at different peripheral body sites (P2-Effort); and baseline shifts in heart rate, (BL-HR-Effort). In conclusion, a clear monotonic relationship was found between several pleth-based parameters and imposed respiratory loadings at the mouth across a range of respiratory rates and flow constrictions. The results suggest that the pleth may provide a measure of changing upper airway dynamics indicative of the effort to breathe. Copyright © 2017 The Author. Published by Elsevier Ltd.. All rights reserved.

Effect of respiratory function training on respiratory function of patients with severe cerebrovascular disease

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Ming GUO

2017-07-01

Full Text Available Objective To investigate the effect of respiratory function training on respiratory function and conscious state of patients with severe cerebrovascular disease (SCVD.  Methods A total of 27 patients with SCVD were divided into control group (N = 17 and observation group (N = 10. Control group received routine drug and rehabilitation treatment, and observation group was added respiratory function training based on routine treatment. The respiratory rate, tidal volume (TV, heart rate, blood pressure and artery oxygen saturation (SaO2 of patients were monitored by breathing machine before and after 4-week treatment. Meanwhile, arterial blood gas analysis was used to detect arterial partial pressure of oxygen (PaO2, oxygenation index, partial pressure of carbon dioxide (PaCO2 and pH value. At the same time, Glasgow Coma Scale (GCS was used to evaluate the conscious state of patients.  Results All patients successfully completed 4-week rehabilitation training, without asphyxia, arrhythmia or other adverse events. Compared with before training, the respiratory rate (P = 0.006 and pH value (P = 0.010 were significantly decreased, while SaO2 (P = 0.001, oxygenation index (P = 0.000 and GCS scores (P = 0.004, 0.017 were significantly increased in both groups of patients after training. There was no statistically significant difference between 2 groups on respiratory function indexes and GCS scores after training (P > 0.05, for all. Conclusions Respiratory function training did not significantly improve the respiratory function and conscious state of patients with SCVD, yet to be further studied. Randomized controlled clinical trials with larger, layered samples and long-term prognosis observation are needed. Examination method of respiratory function of SCVD patients is also a topic to be explored.  DOI: 10.3969/j.issn.1672-6731.2017.04.007

Human metapneumovirus and respiratory syncytial virus in hospitalized danish children with acute respiratory tract infection

DEFF Research Database (Denmark)

von Linstow, Marie-Louise; Henrik Larsen, Hans; Koch, Anders

2004-01-01

The newly discovered human metapneumovirus (hMPV) has been shown to be associated with respiratory illness. We determined the frequencies and clinical features of hMPV and respiratory syncytial virus (RSV) infections in 374 Danish children with 383 episodes of acute respiratory tract infection...... children 1-6 months of age. Asthmatic bronchitis was diagnosed in 66.7% of hMPV and 10.6% of RSV-infected children (p respiratory support. hMPV is present in young...

The role of quinone reductase (NQO1) and quinone chemistry in quercetin cytotoxicity

NARCIS (Netherlands)

Gliszczynska-Swiglo, A.; Woude, van der H.; Haan, de L.H.J.; Tyrakowska, B.; Aarts, J.M.M.J.G.; Rietjens, I.M.C.M.

2003-01-01

The effects of quercetin on viability and proliferation of Chinese Hamster Ovary (CHO) cells and CHO cells overexpressing human quinone reductase (CHO+NQO1) were studied to investigate the involvement of the pro-oxidant quinone chemistry of quercetin. The toxicity of menadione was significantly

Positive correlation between decreased cellular uptake, NADPH-glutathione reductase activity and adriamycin resistance in Ehrlich ascites tumor lines.

Science.gov (United States)

Scheulen, M E; Hoensch, H; Kappus, H; Seeber, S; Schmidt, C G

1987-01-01

From a wild type strain of Ehrlich ascites tumor (EATWT) sublines resistant to daunorubicin (EATDNM), etoposide (EATETO), and cisplatinum (EATCIS) have been developed in vivo. Increase in survival and cure rate caused by adriamycin (doxorubicin) have been determined in female NMRI mice which were inoculated i.p. with EAT cells. Adriamycin concentrations causing 50% inhibition of 3H-thymidine (ICT) and 3H-uridine incorporation (ICU) and intracellular adriamycin steady-state concentrations (SSC) were measured in vitro. Adriamycin resistance increased and SSC decreased in the following sequence: EATWT - EATCIS - EATDNM - EATETO. When ICT and ICU were corrected for intracellular adriamycin concentrations in consideration of the different SSC (ICTc, ICUc), ICTc and ICUc still varied up to the 3.2 fold in EATCIS, EATDNM and EATETO in comparison to EATWT. Thus, in addition to different SSC other factors must be responsible for adriamycin resistance. Therefore, enzymes which may play a role in the cytotoxicity related to adriamycin metabolism (NADPH-cytochrome P-450 reductase, NADPH-glutathione reductase, NADP-glucose-6-phosphate dehydrogenase, NADP-isocitrate dehydrogenase) were measured. In contrast to the other parameters determined, NADPH-glutathione reductase was significantly (p less than 0.01) increased up to the 3.2 fold parallel to adriamycin resistance as determined by increase in life span, cure rate, ICTc, and ICUc, respectively. It is concluded that high activities of NADPH-glutathione reductase may contribute to an increase in adriamycin resistance of malignant tumors.

Effect of pharmaceutical potential endocrine disruptor compounds on protein disulfide isomerase reductase activity using di-eosin-oxidized-glutathione.

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Danièle Klett

Full Text Available BACKGROUND: Protein Disulfide Isomerase (PDI in the endoplasmic reticulum of all cells catalyzes the rearrangement of disulfide bridges during folding of membrane and secreted proteins. As PDI is also known to bind various molecules including hormones such as estradiol and thyroxin, we considered the hypothesis that adverse effects of endocrine-disrupter compounds (EDC could be mediated through their interaction with PDI leading to defects in membrane or secreted proteins. METHODOLOGY/PRINCIPAL FINDINGS: Taking advantage of the recent description of the fluorescence self quenched substrate di-eosin-oxidized-glutathione (DiE-GSSG, we determined kinetically the effects of various potential pharmaceutical EDCs on the in-vitro reductase activity of bovine liver PDI by measuring the fluorescence of the reaction product (E-GSH. Our data show that estrogens (ethynylestradiol and bisphenol-A as well as indomethacin exert an inhibition whereas medroxyprogesteroneacetate and nortestosterone exert a potentiation of bovine PDI reductase activity. CONCLUSIONS: The present data indicate that the tested EDCs could not only affect endocrine target cells through nuclear receptors as previously shown, but could also affect these and all other cells by positively or negatively affecting PDI activity. The substrate DiE-GSSG has been demonstrated to be a convenient substrate to measure PDI reductase activity in the presence of various potential EDCs. It will certainly be usefull for the screening of potential effect of all kinds of chemicals on PDI reductase activity.

33 CFR 142.39 - Respiratory protection.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Respiratory protection. 142.39... Respiratory protection. (a) Personnel in an atmosphere specified under ANSI Z88.2, requiring the use of respiratory protection equipment shall wear the type of respiratory protection equipment specified in ANSI Z88...

[Measurement of the passive compliance of the total respiratory system in newborn after respiratory insufficiency for risk assessment of respiratory disorders during the first 6 month of life].

Science.gov (United States)

Olechowski, Wiesław; Majorek-Olechowska, Bernadetta

2010-01-01

To evaluate the relationships between postnatal passive respiratory compliance (Crs) and development of respiratory disorders during the first 6 month of life in preterm and full-term infants after respiratory insufficiency. The purpose of this study was to investigate whether other relevant neonatal factors, like degree of prematurity, birth weigh, ventilatory conditions, sepsis, and respiratory disease severity affected this relationship. The passive respiratory compliance was measured by the single occlusion technique in 73 preterm infants after respiratory distress syndrome (RDS), 19 full-term infants after congenital pneumonia and 33 healthy full-term infants. Respiratory function measurements were performed by single occlusion technique, during natural sleep, after acute phase of illness, before discharge from neonatal department. Crs was significantly lower in premature newborns newborns who have suffered from a congenital pneumonia (p = 0.0411), than in healthy full-term newborn infants. Premature infants who have undergone sepsis have significantly decreased Crs in relationship with those who did not have this complication (p = 0.0334). Preterm newborns who have suffered pneumonia during treatment of RDS have significantly frequent respiratory problems during the first 6 month of age (p = 0.043). Full-term infants after congenital pneumonia have more but not significantly frequent respiratory problems than healthy term newborns (p = 0.055) in this period. Decreased neonatal Crs wasn't significantly related to respiratory disorders in age of 6 month of life. Prematurity under 36 week of gestational age, low birth weight and suffering from sepsis in premature infants significantly decreased Crs in newborn. Decreased neonatal Crs in premature and full term infants after respiratory insufficiency wasn't significantly related to respiratory disorders during first 6 month of life. This study has showed significantly increase of respiratory problems in this

Respiratory syncytial virus (RSV)

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RSV; Palivizumab; Respiratory syncytial virus immune globulin; Bronchiolitis - RSV ... Crowe JE. Respiratory syncytial virus. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics . 20th ...

Radiological features of lower respiratory infection by respiratory syncytial virus in infants and young children

International Nuclear Information System (INIS)

Kim, Woo Sun; Kim, In One; Yeon, Kyung Mo; Jang, Seong Hee; Lee, Hoan Jong

1992-01-01

Respiratory syncytial virus is the most common cause of lower respiratory infection (bronchiolitis and pneumonia) of infancy and early childhood. We analyzed clinical and radiological features of 76 patients with lower respiratory infections by respiratory syncytial virus, which were diagnosed by indirect immunofluorescent test or culture of nasal aspirate in Hep-2-cell monolayer, during the period of January- December, 1991. There were peaks of incidences in March-May and November- December, accounting for 87% of eases. Sixty-two cases (82%) were under 1 year of age. Fifty cases (66%) had underlying diseases. Major radiographical findings were overaeration (83%), parahilar peribronchial infiltrates (67%), segmental or subsegmental atelectasis (32%), and segmental or lobar consolidation (16%). In 15 cases (20%), overaeration was the only radiological findings. There was no evidence of pleural effusion or lymph node enlargement in all cases. By considering clinical features (symptoms, age, underlying diseases, epidemic seasons) in addition to the radiological findings, radiologists would be familiar with lower respiratory infection by respiratory syncytial virus. Air space consolidation, which is generally thought to represent bacterial pneumonia, is also observed not infrequently in respiratory syncytial virus infection

Metagenomic analysis of viral diversity in respiratory samples from patients with respiratory tract infections in Kuwait.

Science.gov (United States)

Madi, Nada; Al-Nakib, Widad; Mustafa, Abu Salim; Habibi, Nazima

2018-03-01

A metagenomic approach based on target independent next-generation sequencing has become a known method for the detection of both known and novel viruses in clinical samples. This study aimed to use the metagenomic sequencing approach to characterize the viral diversity in respiratory samples from patients with respiratory tract infections. We have investigated 86 respiratory samples received from various hospitals in Kuwait between 2015 and 2016 for the diagnosis of respiratory tract infections. A metagenomic approach using the next-generation sequencer to characterize viruses was used. According to the metagenomic analysis, an average of 145, 019 reads were identified, and 2% of these reads were of viral origin. Also, metagenomic analysis of the viral sequences revealed many known respiratory viruses, which were detected in 30.2% of the clinical samples. Also, sequences of non-respiratory viruses were detected in 14% of the clinical samples, while sequences of non-human viruses were detected in 55.8% of the clinical samples. The average genome coverage of the viruses was 12% with the highest genome coverage of 99.2% for respiratory syncytial virus, and the lowest was 1% for torque teno midi virus 2. Our results showed 47.7% agreement between multiplex Real-Time PCR and metagenomics sequencing in the detection of respiratory viruses in the clinical samples. Though there are some difficulties in using this method to clinical samples such as specimen quality, these observations are indicative of the promising utility of the metagenomic sequencing approach for the identification of respiratory viruses in patients with respiratory tract infections. © 2017 Wiley Periodicals, Inc.

Respiratory Issues in OI

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Respiratory Issues in Osteogenesis Imperfecta \\ Introduction The respiratory system’s job is to bring oxygen into the body and remove carbon dioxide, the waste product of breathing. Because oxygen is the fuel ...

Thermophilic enzymes and their applications in biocatalysis: a robust aldo-keto reductase.

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Willies, Simon; Isupov, Misha; Littlechild, Jennifer

2010-09-01

Extremophiles are providing a good source of novel robust enzymes for use in biocatalysis for the synthesis of new drugs. This is particularly true for the enzymes from thermophilic organisms which are more robust than their mesophilic counterparts to the conditions required for industrial bio-processes. This paper describes a new aldo-keto reductase enzyme from a thermophilic eubacteria, Thermotoga maritima which can be used for the production of primary alcohols. The enzyme has been cloned and over-expressed in Escherichia coli and has been purified and subjected to full biochemical characterization. The aldo-keto reductase can be used for production of primary alcohols using substrates including benzaldehyde, 1,2,3,6-tetrahydrobenzaldehyde and para-anisaldehyde. It is stable up to 80 degrees C, retaining over 60% activity for 5 hours at this temperature. The enzyme at pH 6.5 showed a preference for the forward, carbonyl reduction. The enzyme showed moderate stability with organic solvents, and retained 70% activity in 20% (v/v) isopropanol or DMSO. These properties are favourable for its potential industrial applications.

Reduction of azo dyes by flavin reductase from Citrobacter freundii A1

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Mohd Firdaus Abdul-Wahab

2012-12-01

Full Text Available Citrobacter freundii A1 isolated from a sewage treatment facility was demonstrated to be able to effectively decolorize azo dyes as pure and mixed culture. This study reports on the investigation on the enzymatic systems involved. An assay performed suggested the possible involvement of flavin reductase (Fre as an azo reductase. A heterologouslyexpressed recombinant Fre from C. freundii A1 was used to investigate its involvement in the azo reduction process. Three model dyes were used, namely Acid Red 27 (AR27, Direct Blue 15 (DB15 and Reactive Black 5 (RB5. AR27 was found to be reduced the fastest by Fre, followed by RB5, and lastly DB15. Redox mediators nicotinamide adenine dinucleotide (NADH and riboflavin enhance the reduction, suggesting the redox activity of the enzyme. The rate and extent of reduction of the model dyes correlate well with the reduction potentials (Ep. The data presented here strongly suggest that Fre is one of the enzymes responsible for azo reduction in C. freundii A1, acting via an oxidation-reduction reaction.

Acute respiratory distress syndrome

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... page: //medlineplus.gov/ency/article/000103.htm Acute respiratory distress syndrome To use the sharing features on this page, please enable JavaScript. Acute respiratory distress syndrome (ARDS) is a life-threatening lung ...

Solid solutions of hydrogen uranyl phosphate and hydrogen uranyl arsenate. A family of luminescent, lamellar hosts

International Nuclear Information System (INIS)

Dorhout, P.K.; Rosenthal, G.L.; Ellis, A.B.

1988-01-01

Hydrogen uranyl phosphate, HUO 2 PO 4 x 4H 2 O (HUP), and hydrogen uranyl arsenate, HUO 2 AsO 4 x 4H 2 O (HUAs), form solid solutions of composition HUO 2 (PO 4 ) 1-x (AsO 4 )x (HUPAs), representing a family of lamellar, luminescent solids that can serve as hosts for intercalation chemistry. The solids are prepared by aqueous precipitation reactions from uranyl nitrate and mixtures of phosphoric and arsenic acids; thermogravimetric analysis indicates that the phases are tetrahydrates, like HUP and HUAs. Powder x-ray diffraction data reveal the HUPAs solids to be single phases whose lattice constants increase with X, in rough accord with Vegard's law Spectral shifts observed for the HUPAs samples. Emission from the solids is efficient (quantum yields of ∼ 0.2) and long-lived (lifetimes of ∼ 150 μs), although the measured values are uniformly smaller than those of HUP and HUAs; unimolecular radiative and nonradiative rate constants for excited-state decay of ∼ 1500 and 5000 s -1 , respectively, have been calculated for the compounds. 18 refs., 5 figs., 2 tabs

Acrolein-induced activation of mitogen-activated protein kinase signaling is mediated by alkylation of thioredoxin reductase and thioredoxin 1.

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Randall, Matthew J; Spiess, Page C; Hristova, Milena; Hondal, Robert J; van der Vliet, Albert

2013-01-01

Cigarette smoking remains a major health concern worldwide, and many of the adverse effects of cigarette smoke (CS) can be attributed to its abundant electrophilic aldehydes, such as acrolein (2-propenal). Previous studies indicate that acrolein readily reacts with thioredoxin reductase 1 (TrxR1), a critical enzyme involved in regulation of thioredoxin (Trx)-mediated redox signaling, by alkylation at its selenocysteine (Sec) residue. Because alkylation of Sec within TrxR1 has significant implications for its enzymatic function, we explored the potential importance of TrxR1 alkylation in acrolein-induced activation or injury of bronchial epithelial cells. Exposure of human bronchial epithelial HBE1 cells to acrolein (1-30 μM) resulted in dose-dependent loss of TrxR thioredoxin reductase activity, which coincided with its alkylation, as determined by biotin hydrazide labeling, and was independent of initial GSH status. To test the involvement of TrxR1 in acrolein responses in HBE1 cells, we suppressed TrxR1 using siRNA silencing or augmented TrxR1 by cell supplementation with sodium selenite. Acrolein exposure of HBE1 cells induced dose-dependent activation of the MAP kinases, extracellular regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, and activation of JNK was markedly enhanced after selenite-mediated induction of TrxR1, and was associated with increased alkylation of TrxR1. Conversely, siRNA silencing of TrxR1 significantly suppressed the ability of acrolein to activate JNK, and also appeared to attenuate acrolein-dependent activation of ERK and p38. Alteration of initial TrxR1 levels by siRNA or selenite supplementation also affected initial Trx1 redox status and acrolein-mediated alkylation of Trx1, but did not significantly affect acrolein-mediated activation of HO-1 or cytotoxicity. Collectively, our findings indicate that alkylation of TrxR1 and/or Trx1 may contribute directly to acrolein-mediated activation of MAP kinases such as JNK, and

Acrolein-induced activation of mitogen-activated protein kinase signaling is mediated by alkylation of thioredoxin reductase and thioredoxin 1

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Matthew J. Randall

2013-01-01

Full Text Available Cigarette smoking remains a major health concern worldwide, and many of the adverse effects of cigarette smoke (CS can be attributed to its abundant electrophilic aldehydes, such as acrolein (2-propenal. Previous studies indicate that acrolein readily reacts with thioredoxin reductase 1 (TrxR1, a critical enzyme involved in regulation of thioredoxin (Trx-mediated redox signaling, by alkylation at its selenocysteine (Sec residue. Because alkylation of Sec within TrxR1 has significant implications for its enzymatic function, we explored the potential importance of TrxR1 alkylation in acrolein-induced activation or injury of bronchial epithelial cells. Exposure of human bronchial epithelial HBE1 cells to acrolein (1–30 μM resulted in dose-dependent loss of TrxR thioredoxin reductase activity, which coincided with its alkylation, as determined by biotin hydrazide labeling, and was independent of initial GSH status. To test the involvement of TrxR1 in acrolein responses in HBE1 cells, we suppressed TrxR1 using siRNA silencing or augmented TrxR1 by cell supplementation with sodium selenite. Acrolein exposure of HBE1 cells induced dose-dependent activation of the MAP kinases, extracellular regulated kinase (ERK, c-Jun N-terminal kinase (JNK, and p38, and activation of JNK was markedly enhanced after selenite-mediated induction of TrxR1, and was associated with increased alkylation of TrxR1. Conversely, siRNA silencing of TrxR1 significantly suppressed the ability of acrolein to activate JNK, and also appeared to attenuate acrolein-dependent activation of ERK and p38. Alteration of initial TrxR1 levels by siRNA or selenite supplementation also affected initial Trx1 redox status and acrolein-mediated alkylation of Trx1, but did not significantly affect acrolein-mediated activation of HO-1 or cytotoxicity. Collectively, our findings indicate that alkylation of TrxR1 and/or Trx1 may contribute directly to acrolein-mediated activation of MAP kinases

Resonance Raman spectra of the copper-sulfur chromophores in Achromobacter cycloclastes nitrite reductase.

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Dooley, D M; Moog, R S; Liu, M Y; Payne, W J; LeGall, J

1988-10-15

Resonance Raman spectroscopy at ambient temperature and 77 K has been used to probe the structures of the copper sites in Achromobacter cycloclastes nitrite reductase. This enzyme contains three copper ions per protein molecule and has two principal electronic absorption bands with lambda max values of 458 and 585 nm. Comparisons between the resonance Raman spectra of nitrite reductase and blue copper proteins establish that both the 458 and 585 nm bands are associated with Cu(II)-S(Cys) chromophores. A histidine ligand probably is also present. Different sets of vibrational frequencies are observed with 457.9 nm (ambient) or 476.1 nm (77 K) excitation as compared with 590 nm (ambient) or 593 nm (77 K) excitation. Excitation profiles indicate that the 458 and 585 nm absorption bands are associated with separate [Cu(II)-S(Cys)N(His)] sites or with inequivalent and uncoupled cysteine ligands in the same site. The former possibility is considered to be more likely.

Molecular cloning and characterization of Fasciola gigantica thioredoxin-glutathione reductase.

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Changklungmoa, Narin; Kueakhai, Pornanan; Sangpairoj, Kant; Chaichanasak, Pannigan; Jaikua, Wipaphorn; Riengrojpitak, Suda; Sobhon, Prasert; Chaithirayanon, Kulathida

2015-06-01

The Fasciola gigantica thioredoxin-glutathione reductase (FgTGR) gene is a fusion between thioredoxin reductase (TR) and a glutaredoxin (Grx) gene. FgTGR was cloned by polymerase chain reaction (PCR) from adult complementary DNA (cDNA), and its sequences showed two isoforms, i.e., the cytosolic and mitochondrial FgTGR. Cytosolic FgTGR (cytFgTGR) was composed of 2370 bp, and its peptide had no signal sequence and hence was not a secreted protein. Mitochondrial FgTGR (mitFgTGR) was composed of 2506 bp with a signal peptide of 43 amino acids; therefore, it was a secreted protein. The putative cytFgTGR and mitFgTGR peptides comprised of 598 and 641 amino acids, respectively, with a molecular weight of 65.8 kDa for cytFgTGR and mitFgTGR, with a conserved sequence (CPYC) of TR, and ACUG and CVNVGC of Grx domains. The recombinant FgTGR (rFgTGR) was expressed in Escherichia coli BL21 (DE3) and used for production for a polyclonal antibody in rabbits (anti-rFgTGR). The FgTGR protein expression, estimated by indirect ELISA using the rabbit anti-rFgTGR as probe, showed high levels of expression in eggs, and 2- and 4-week-old juveniles and adults. The rFgTGR exhibited specific activities in the 5,5'-dithiobis (2-nitro-benzoic acid) (DTNB) reductase assay for TR activity and in β-hydroxyethul disulfide (HED) for Grx activity. When analyzed by immunoblotting and immunohistochemistry, rabbit anti-rFgTGR reacted with natural FgTGR at a molecular weight of 66 kDa from eggs, whole body fraction (WB) of metacercariae, NEJ, 2- and 4-week-old juveniles and adults, and the tegumental antigen (TA) of adult. The FgTGR protein was expressed at high levels in the tegument of 2- and 4-week-old juveniles. The FgTGR may be one of the major factors acting against oxidative stresses that can damage the parasite; hence, it could be considered as a novel vaccine or a drug target.

Upper respiratory tract (image)

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The major passages and structures of the upper respiratory tract include the nose or nostrils, nasal cavity, mouth, throat (pharynx), and voice box (larynx). The respiratory system is lined with a mucous membrane that ...

Respiratory cancer database: An open access database of respiratory cancer gene and miRNA.

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Choubey, Jyotsna; Choudhari, Jyoti Kant; Patel, Ashish; Verma, Mukesh Kumar

2017-01-01

Respiratory cancer database (RespCanDB) is a genomic and proteomic database of cancer of respiratory organ. It also includes the information of medicinal plants used for the treatment of various respiratory cancers with structure of its active constituents as well as pharmacological and chemical information of drug associated with various respiratory cancers. Data in RespCanDB has been manually collected from published research article and from other databases. Data has been integrated using MySQL an object-relational database management system. MySQL manages all data in the back-end and provides commands to retrieve and store the data into the database. The web interface of database has been built in ASP. RespCanDB is expected to contribute to the understanding of scientific community regarding respiratory cancer biology as well as developments of new way of diagnosing and treating respiratory cancer. Currently, the database consist the oncogenomic information of lung cancer, laryngeal cancer, and nasopharyngeal cancer. Data for other cancers, such as oral and tracheal cancers, will be added in the near future. The URL of RespCanDB is http://ridb.subdic-bioinformatics-nitrr.in/.

A Review on Human Respiratory Modeling.

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Ghafarian, Pardis; Jamaati, Hamidreza; Hashemian, Seyed Mohammadreza

2016-01-01

Input impedance of the respiratory system is measured by forced oscillation technique (FOT). Multiple prior studies have attempted to match the electromechanical models of the respiratory system to impedance data. Since the mechanical behavior of airways and the respiratory system as a whole are similar to an electrical circuit in a combination of series and parallel formats some theories were introduced according to this issue. It should be noted that, the number of elements used in these models might be less than those required due to the complexity of the pulmonary-chest wall anatomy. Various respiratory models have been proposed based on this idea in order to demonstrate and assess the different parts of respiratory system related to children and adults data. With regard to our knowledge, some of famous respiratory models in related to obstructive, restrictive diseases and also Acute Respiratory Distress Syndrome (ARDS) are reviewed in this article.

Impact of soil organic carbon on monosodium methyl arsenate (MSMA) sorption and species transformation.

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Ou, Ling; Gannon, Travis W; Polizzotto, Matthew L

2017-11-01

Monosodium methyl arsenate (MSMA), a common arsenical herbicide, is a major contributor of anthropogenic arsenic (As) to the environment. Uncertainty about controls on MSMA fate and the rates and products of MSMA species transformation limits effective MSMA regulation and management. The main objectives of this research were to quantify the kinetics and mechanistic drivers of MSMA species transformation and removal from solution by soil. Laboratory MSMA incubation studies with two soils and varying soil organic carbon (SOC) levels were conducted. Arsenic removal from solution was more extensive and faster in sandy clay loam incubations than sand incubations, but for both systems, As removal was biphasic, with initially fast removal governed by sorption, followed by slower As removal limited by species transformation. Dimethylarsinic acid was the dominant product of species transformation at first, but inorganic As(V) was the ultimate transformation product by experiment ends. SOC decreased As removal and enhanced As species transformation, and SOC content had linear relationships with As removal rates (R 2  = 0.59-0.95) for each soil and reaction phase. These results reveal the importance of edaphic conditions on inorganic As production and overall mobility of As following MSMA use, and such information should be considered in MSMA management and regulatory decisions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Avian respiratory system disorders

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Olsen, Glenn H.

1989-01-01

Diagnosing and treating respiratory diseases in avian species requires a basic knowledge about the anatomy and physiology of this system in birds. Differences between mammalian and avian respiratory system function, diagnosis, and treatment are highlighted.

Molecular Diagnosis of 5α-Reductase Type II Deficiency in Brazilian Siblings with 46,XY Disorder of Sex Development

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Maricilda Palandi de Mello

2011-12-01

Full Text Available The steroid 5α-reductase type II enzyme catalyzes the conversion of testosterone (T to dihydrotestosterone (DHT, and its deficiency leads to undervirilization in 46,XY individuals, due to an impairment of this conversion in genital tissues. Molecular analysis in the steroid 5α-reductase type II gene (SRD5A2 was performed in two 46,XY female siblings. SRD5A2 gene sequencing revealed that the patients were homozygous for p.Gln126Arg missense mutation, which results from the CGA > CAA nucleotide substitution. The molecular result confirmed clinical diagnosis of 46,XY disorder of sex development (DSD for the older sister and directed the investigation to other family members. Studies on SRD5A2 protein structure showed severe changes at NADPH binding region indicating that structural modeling analysis can be useful to evaluate the deleterious role of a mutation as causing 5α-reductase type II enzyme deficiency.

Methylenetetrahydrofolate reductase (MTHFR) deficiency presenting as a rash.

LENUS (Irish Health Repository)

Crushell, Ellen

2012-09-01

We report on the case of a 2-year-old girl recently diagnosed with Methylenetetrahydrofolate reductase (MTHFR) deficiency who originally presented in the neonatal period with a distinctive rash. At 11 weeks of age she developed seizures, she had acquired microcephaly and developmental delay. The rash deteriorated dramatically following commencement of phenobarbitone; both rash and seizures abated following empiric introduction of pyridoxine and folinic acid as treatment of possible vitamin responsive seizures. We postulate that phenobarbitone in combination with MTHFR deficiency may have caused her rash to deteriorate and subsequent folinic acid was helpful in treating the rash and preventing further acute neurological decline as commonly associated with this condition.

Purification, crystallization and preliminary X-ray analysis of 3-hydroxy-3-methylglutaryl-coenzyme A reductase of Streptococcus pneumoniae

International Nuclear Information System (INIS)

Zhang, Liping; Feng, Lingling; Zhou, Li; Gui, Jie; Wan, Jian; Hu, Xiaopeng

2010-01-01

3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase of Streptococcus pneumoniae has been cloned, overexpressed and purified to homogeneity using Ni–NTA affinity chromatography. Crystals were obtained using the hanging-drop vapour-diffusion method. Class II 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductases are potential targets for novel antibiotic development. In order to obtain a precise structural model for use in virtual screening and inhibitor design, HMG-CoA reductase of Streptococcus pneumoniae was cloned, overexpressed and purified to homogeneity using Ni–NTA affinity chromatography. Crystals were obtained using the hanging-drop vapour-diffusion method. A complete data set was collected from a single frozen crystal on a home X-ray source. The crystal diffracted to 2.3 Å resolution and belonged to the orthorhombic space group C222 1 , with unit-cell parameters a = 773.4836, b = 90.3055, c = 160.5592 Å, α = β = γ = 90°. Assuming the presence of two molecules in the asymmetric unit, the solvent content was estimated to be 54.1% (V M = 2.68 Å 3 Da −1 )

Homology modeling of dissimilatory APS reductases (AprBA of sulfur-oxidizing and sulfate-reducing prokaryotes.

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Birte Meyer

Full Text Available BACKGROUND: The dissimilatory adenosine-5'-phosphosulfate (APS reductase (cofactors flavin adenine dinucleotide, FAD, and two [4Fe-4S] centers catalyzes the transformation of APS to sulfite and AMP in sulfate-reducing prokaryotes (SRP; in sulfur-oxidizing bacteria (SOB it has been suggested to operate in the reverse direction. Recently, the three-dimensional structure of the Archaeoglobus fulgidus enzyme has been determined in different catalytically relevant states providing insights into its reaction cycle. METHODOLOGY/PRINCIPAL FINDINGS: Full-length AprBA sequences from 20 phylogenetically distinct SRP and SOB species were used for homology modeling. In general, the average accuracy of the calculated models was sufficiently good to allow a structural and functional comparison between the beta- and alpha-subunit structures (78.8-99.3% and 89.5-96.8% of the AprB and AprA main chain atoms, respectively, had root mean square deviations below 1 A with respect to the template structures. Besides their overall conformity, the SRP- and SOB-derived models revealed the existence of individual adaptations at the electron-transferring AprB protein surface presumably resulting from docking to different electron donor/acceptor proteins. These structural alterations correlated with the protein phylogeny (three major phylogenetic lineages: (1 SRP including LGT-affected Archaeoglobi and SOB of Apr lineage II, (2 crenarchaeal SRP Caldivirga and Pyrobaculum, and (3 SOB of the distinct Apr lineage I and the presence of potential APS reductase-interacting redox complexes. The almost identical protein matrices surrounding both [4Fe-4S] clusters, the FAD cofactor, the active site channel and center within the AprB/A models of SRP and SOB point to a highly similar catalytic process of APS reduction/sulfite oxidation independent of the metabolism type the APS reductase is involved in and the species it has been originated from. CONCLUSIONS: Based on the comparative

Biocatalysis with thermostable enzymes: structure and properties of a thermophilic 'ene'-reductase related to old yellow enzyme.

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Adalbjörnsson, Björn V; Toogood, Helen S; Fryszkowska, Anna; Pudney, Christopher R; Jowitt, Thomas A; Leys, David; Scrutton, Nigel S

2010-01-25

We report the crystal structure of a thermophilic "ene" reductase (TOYE) isolated from Thermoanaerobacter pseudethanolicus E39. The crystal structure reveals a tetrameric enzyme and an active site that is relatively large compared to most other structurally determined and related Old Yellow Enzymes. The enzyme adopts higher order oligomeric states (octamers and dodecamers) in solution, as revealed by sedimentation velocity and multiangle laser light scattering. Bead modelling indicates that the solution structure is consistent with the basic tetrameric structure observed in crystallographic studies and electron microscopy. TOYE is stable at high temperatures (T(m)>70 degrees C) and shows increased resistance to denaturation in water-miscible organic solvents compared to the mesophilic Old Yellow Enzyme family member, pentaerythritol tetranitrate reductase. TOYE has typical ene-reductase properties of the Old Yellow Enzyme family. There is currently major interest in using Old Yellow Enzyme family members in the preparative biocatalysis of a number of activated alkenes. The increased stability of TOYE in organic solvents is advantageous for biotransformations in which water-miscible organic solvents and biphasic reaction conditions are required to both deliver novel substrates and minimize product racemisation.

Management of respiratory symptoms in ALS.

LENUS (Irish Health Repository)

Hardiman, Orla

2012-02-01

Respiratory insufficiency is a frequent feature of ALS and is present in almost all cases at some stage of the illness. It is the commonest cause of death in ALS. FVC is used as important endpoint in many clinical trials, and in decision-making events for patients with ALS, although there are limitations to its predictive utility. There are multiple causes of respiratory muscle failure, all of which act to produce a progressive decline in pulmonary function. Diaphragmatic fatigue and weakness, coupled with respiratory muscle weakness, lead to reduced lung compliance and atelectasis. Increased secretions increase the risk of aspiration pneumonia, which further compromises respiratory function. Bulbar dysfunction can lead to nutritional deficiency, which in turn increases the fatigue of respiratory muscles. Early recognition of respiratory decline and symptomatic intervention, including non-invasive ventilation can significantly enhance both quality of life and life expectancy in ALS. Patients with respiratory failure should be advised to consider an advance directive to avoid emergency mechanical ventilation.

Management of respiratory symptoms in ALS.

LENUS (Irish Health Repository)

Hardiman, Orla

2011-03-01

Respiratory insufficiency is a frequent feature of ALS and is present in almost all cases at some stage of the illness. It is the commonest cause of death in ALS. FVC is used as important endpoint in many clinical trials, and in decision-making events for patients with ALS, although there are limitations to its predictive utility. There are multiple causes of respiratory muscle failure, all of which act to produce a progressive decline in pulmonary function. Diaphragmatic fatigue and weakness, coupled with respiratory muscle weakness, lead to reduced lung compliance and atelectasis. Increased secretions increase the risk of aspiration pneumonia, which further compromises respiratory function. Bulbar dysfunction can lead to nutritional deficiency, which in turn increases the fatigue of respiratory muscles. Early recognition of respiratory decline and symptomatic intervention, including non-invasive ventilation can significantly enhance both quality of life and life expectancy in ALS. Patients with respiratory failure should be advised to consider an advance directive to avoid emergency mechanical ventilation.

Functional properties and structural characterization of rice δ1-pyrroline-5-carboxylate reductase

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Giuseppe eForlani

2015-07-01

Full Text Available The majority of plant species accumulate high intracellular levels of proline to cope with hyperosmotic stress conditions. Proline synthesis from glutamate is tightly regulated at both the transcriptional and the translational levels, yet little is known about the mechanisms for post-translational regulation of the enzymatic activities involved. The gene coding in rice (Oryza sativa L. for δ1-pyrroline-5-carboxylate (P5C reductase, the enzyme that catalyzes the second and final step in this pathway, was isolated and expressed in E. coli. The structural and functional properties of the affinity-purified protein were characterized. As for most species, rice P5C reductase was able to use in vitro either NADH or NADPH as the electron donor. However, strikingly different effects of cations and anions were found depending on the pyridine nucleotide used, namely inhibition of NADH-dependent activity and stimulation of NADPH-dependent activity. Moreover, physiological concentrations of proline and NADP+ were strongly inhibitory for the NADH-dependent reaction, whereas the NADPH-dependent activity was mildly affected. Our results suggest that only NADPH may be used in vivo and that stress-dependent variations in ion homeostasis and NADPH/NADP+ ratio could modulate enzyme activity, being functional in promoting proline accumulation and potentially also adjusting NADPH consumption during the defense against hyperosmotic stress. The apparent molecular weight of the native protein observed in size exclusion chromatography indicated a high oligomerization state. We also report the first crystal structure of a plant P5C reductase at 3.40-Å resolution, showing a decameric quaternary assembly. Based on the structure, it was possible to identify dynamic structural differences among rice, human and bacterial enzymes.

Sunflower (Helianthus annuus) fatty acid synthase complex: enoyl-[acyl carrier protein]-reductase genes.

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González-Thuillier, Irene; Venegas-Calerón, Mónica; Garcés, Rafael; von Wettstein-Knowles, Penny; Martínez-Force, Enrique

2015-01-01

Enoyl-[acyl carrier protein]-reductases from sunflower. A major factor contributing to the amount of fatty acids in plant oils are the first steps of their synthesis. The intraplastidic fatty acid biosynthetic pathway in plants is catalysed by type II fatty acid synthase (FAS). The last step in each elongation cycle is carried out by the enoyl-[ACP]-reductase, which reduces the dehydrated product of β-hydroxyacyl-[ACP] dehydrase using NADPH or NADH. To determine the mechanisms involved in the biosynthesis of fatty acids in sunflower (Helianthus annuus) seeds, two enoyl-[ACP]-reductase genes have been identified and cloned from developing seeds with 75 % identity: HaENR1 (GenBank HM021137) and HaENR2 (HM021138). The two genes belong to the ENRA and ENRB families in dicotyledons, respectively. The genetic duplication most likely originated after the separation of di- and monocotyledons. RT-qPCR revealed distinct tissue-specific expression patterns. Highest expression of HaENR1 was in roots, stems and developing cotyledons whereas that of H a ENR2 was in leaves and early stages of seed development. Genomic DNA gel blot analyses suggest that both are single-copy genes. In vivo activity of the ENR enzymes was tested by complementation experiments with the JP1111 fabI(ts) E. coli strain. Both enzymes were functional demonstrating that they interacted with the bacterial FAS components. That different fatty acid profiles resulted infers that the two Helianthus proteins have different structures, substrate specificities and/or reaction rates. The latter possibility was confirmed by in vitro analysis with affinity-purified heterologous-expressed enzymes that reduced the crotonyl-CoA substrate using NADH with different V max.

Management of Postoperative Respiratory Failure.

Science.gov (United States)

Mulligan, Michael S; Berfield, Kathleen S; Abbaszadeh, Ryan V

2015-11-01

Despite best efforts, postoperative complications such as postoperative respiratory failure may occur and prompt recognition of the process and management is required. Postoperative respiratory failure, such as postoperative pneumonia, postpneumonectomy pulmonary edema, acute respiratory distress-like syndromes, and pulmonary embolism, are associated with high morbidity and mortality. The causes of these complications are multifactorial and depend on preoperative, intraoperative, and postoperative factors, some of which are modifiable. The article identifies some of the risk factors, causes, and treatment strategies for successful management of the patient with postoperative respiratory failure. Copyright © 2015 Elsevier Inc. All rights reserved.

Crystal structure of conjugated polyketone reductase (CPR-C1) from Candida parapsilosis IFO 0708 complexed with NADPH.

Science.gov (United States)

Qin, Hui-Min; Yamamura, Akihiro; Miyakawa, Takuya; Kataoka, Michihiko; Maruoka, Shintaro; Ohtsuka, Jun; Nagata, Koji; Shimizu, Sakayu; Tanokura, Masaru

2013-11-01

Conjugated polyketone reductase (CPR-C1) from Candida parapsilosis IFO 0708 is a member of the aldo-keto reductase (AKR) superfamily and reduces ketopantoyl lactone to d-pantoyl lactone in a NADPH-dependent and stereospecific manner. We determined the crystal structure of CPR-C1.NADPH complex at 2.20 Å resolution. CPR-C1 adopted a triose-phosphate isomerase (TIM) barrel fold at the core of the structure in which Thr25 and Lys26 of the GXGTX motif bind uniquely to the adenosine 2'-phosphate group of NADPH. This finding provides a novel structural basis for NADPH binding of the AKR superfamily. Copyright © 2013 Wiley Periodicals, Inc.

Respiratory monitoring with an acceleration sensor

International Nuclear Information System (INIS)

Ono, Tomohiro; Takegawa, Hideki; Ageishi, Tatsuya; Takashina, Masaaki; Numasaki, Hodaka; Matsumoto, Masao; Teshima, Teruki

2011-01-01

Respiratory gating radiotherapy is used to irradiate a local area and to reduce normal tissue toxicity. There are certain methods for the detection of tumor motions, for example, using internal markers or an external respiration signal. However, because some of these respiratory monitoring systems require special or expensive equipment, respiratory monitoring can usually be performed only in limited facilities. In this study, the feasibility of using an acceleration sensor for respiratory monitoring was evaluated. The respiratory motion was represented by means of a platform and measured five times with the iPod touch (registered) at 3, 4 and 5 s periods of five breathing cycles. For these three periods of the reference waveform, the absolute means ± standard deviation (SD) of displacement were 0.45 ± 0.34 mm, 0.33 ± 0.24 mm and 0.31 ± 0.23 mm, respectively. On the other hand, the corresponding absolute means ± SD for the periods were 0.04 ± 0.09 s, 0.04 ± 0.02 s and 0.06 ± 0.04 s. The accuracy of respiratory monitoring using the acceleration sensor was satisfactory in terms of the absolute means ± SD. Using the iPod touch (registered) for respiratory monitoring does not need special equipment and makes respiratory monitoring easier. For these reasons, this system is a viable alternative to other respiratory monitoring systems.

Quantitation of respiratory viruses in relation to clinical course in children with acute respiratory tract infections

NARCIS (Netherlands)

Jansen, Rogier R.; Schinkel, Janke; dek, Irene; Koekkoek, Sylvie M.; Visser, Caroline E.; de Jong, Menno D.; Molenkamp, Richard; Pajkrt, Dasja

2010-01-01

Quantitation of respiratory viruses by PCR could potentially aid in clinical interpretation of PCR results. We conducted a study in children admitted with acute respiratory tract infections to study correlations between the clinical course of illness and semiquantitative detection of 14 respiratory

Properties of latent and thiol-activated rat hepatic 3-hydroxy-3-methylglutaryl-coenzyme A reductase and regulation of enzyme activity.

Science.gov (United States)

Dotan, I; Shechter, I

1983-10-15

The effect of the thiols glutathione (GSH), dithiothreitol (DTT), and dithioerythritol (DTE) on the conversion of an inactive, latent form (El) of rat liver 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase, EC 1.1.1.34) to a catalyticaly active form (Ea) is examined. Latent hepatic microsomal HMG-CoA reductase is activated to a similar degree of activation by DTT and DTE and to a lower extent by GSH. All three thiols affect both Km and Vmax values of the enzyme toward HMG-CoA and NADPH. Studies of the effect of DTT on the affinity binding of HMG-CoA reductase to agarose-hexane-HMG-CoA (AG-HMG-CoA) resin shows that thiols are necessary for the binding of the enzyme to the resin. Removal of DTT from AG-HMG-CoA-bound soluble Ea (active enzyme) does not cause dissociation of the enzyme from the resin at low salt concentrations. Substitution of DTT by NADPH does not promote binding of soluble El (latent enzyme) to AG-HMG-CoA. The enzymatic activity of Ea in the presence of DTT and GSH indicates that these thiols compete for the same binding site on the enzyme. Diethylene glycol disulfide (ESSE) and glutathione disulfide (GSSG) inhibit the activity of Ea. ESSE is more effective for the inhibition of Ea than GSSG, causing a higher degree of maximal inhibition and affecting the enzymatic activity at lower concentrations. A method is described for the rapid conversion of soluble purified Ea to El using gel-filtration chromatography on Bio-Gel P-4 columns. These combined results point to the importance of the thiol/disulfide ratio for the modulation of hepatic HMG-CoA reductase activity.

Respiratory innate immune proteins differentially modulate the neutrophil respiratory burst response to influenza A virus

DEFF Research Database (Denmark)

White, Mitchell R; Crouch, Erika; Vesona, Jenny

2005-01-01

of IAV with SP-D in vitro strongly increases neutrophil respiratory burst responses to the virus. Several factors are shown to modify this apparent proinflammatory effect of SP-D. Although multimeric forms of SP-D show dose-dependent augmentation of respiratory burst responses, trimeric, single-arm forms...... of IAV while reducing the respiratory burst response to virus....

A Rational Approach to Identify Inhibitors of Mycobacterium tuberculosis Enoyl Acyl Carrier Protein Reductase

Czech Academy of Sciences Publication Activity Database

Chhabria, M. T.; Parmar, K. B.; Brahmkshatriya, Pathik

2013-01-01

Roč. 19, č. 21 (2013), s. 3878-3883 ISSN 1381-6128 Institutional support: RVO:61388963 Keywords : mycobacterium tuberculosis * enoyl acyl carrier protein reductase * pharmacophore modeling * molecular docking * binding interactions Subject RIV: FR - Pharmacology ; Medidal Chemistry Impact factor: 3.288, year: 2013

Glutathione-supported arsenate reduction coupled to arsenolysis catalyzed by ornithine carbamoyl transferase

International Nuclear Information System (INIS)

Nemeti, Balazs; Gregus, Zoltan

2009-01-01

Three cytosolic phosphorolytic/arsenolytic enzymes, (purine nucleoside phosphorylase [PNP], glycogen phosphorylase, glyceraldehyde-3-phosphate dehydrogenase) have been shown to mediate reduction of arsenate (AsV) to the more toxic arsenite (AsIII) in a thiol-dependent manner. With unknown mechanism, hepatic mitochondria also reduce AsV. Mitochondria possess ornithine carbamoyl transferase (OCT), which catalyzes phosphorolytic or arsenolytic citrulline cleavage; therefore, we examined if mitochondrial OCT facilitated AsV reduction in presence of glutathione. Isolated rat liver mitochondria were incubated with AsV, and AsIII formed was quantified. Glutathione-supplemented permeabilized or solubilized mitochondria reduced AsV. Citrulline (substrate for OCT-catalyzed arsenolysis) increased AsV reduction. The citrulline-stimulated AsV reduction was abolished by ornithine (OCT substrate inhibiting citrulline cleavage), phosphate (OCT substrate competing with AsV), and the OCT inhibitor norvaline or PALO, indicating that AsV reduction is coupled to OCT-catalyzed arsenolysis of citrulline. Corroborating this conclusion, purified bacterial OCT mediated AsV reduction in presence of citrulline and glutathione with similar responsiveness to these agents. In contrast, AsIII formation by intact mitochondria was unaffected by PALO and slightly stimulated by citrulline, ornithine, and norvaline, suggesting minimal role for OCT in AsV reduction in intact mitochondria. In addition to OCT, mitochondrial PNP can also mediate AsIII formation; however, its role in AsV reduction appears severely limited by purine nucleoside supply. Collectively, mitochondrial and bacterial OCT promote glutathione-dependent AsV reduction with coupled arsenolysis of citrulline, supporting the hypothesis that AsV reduction is mediated by phosphorolytic/arsenolytic enzymes. Nevertheless, because citrulline cleavage is disfavored physiologically, OCT may have little role in AsV reduction in vivo.

Effects of respiratory muscle work on respiratory and locomotor blood flow during exercise.

Science.gov (United States)

Dominelli, Paolo B; Archiza, Bruno; Ramsook, Andrew H; Mitchell, Reid A; Peters, Carli M; Molgat-Seon, Yannick; Henderson, William R; Koehle, Michael S; Boushel, Robert; Sheel, A William

2017-11-01

What is the central question of this study? Does manipulation of the work of breathing during high-intensity exercise alter respiratory and locomotor muscle blood flow? What is the main finding and its importance? We found that when the work of breathing was reduced during exercise, respiratory muscle blood flow decreased, while locomotor muscle blood flow increased. Conversely, when the work of breathing was increased, respiratory muscle blood flow increased, while locomotor muscle blood flow decreased. Our findings support the theory of a competitive relationship between locomotor and respiratory muscles during intense exercise. Manipulation of the work of breathing (WOB) during near-maximal exercise influences leg blood flow, but the effects on respiratory muscle blood flow are equivocal. We sought to assess leg and respiratory muscle blood flow simultaneously during intense exercise while manipulating WOB. Our hypotheses were as follows: (i) increasing the WOB would increase respiratory muscle blood flow and decrease leg blood flow; and (ii) decreasing the WOB would decrease respiratory muscle blood flow and increase leg blood flow. Eight healthy subjects (n = 5 men, n = 3 women) performed a maximal cycle test (day 1) and a series of constant-load exercise trials at 90% of peak work rate (day 2). On day 2, WOB was assessed with oesophageal balloon catheters and was increased (via resistors), decreased (via proportional assist ventilation) or unchanged (control) during the trials. Blood flow was assessed using near-infrared spectroscopy optodes placed over quadriceps and the sternocleidomastoid muscles, coupled with a venous Indocyanine Green dye injection. Changes in WOB were significantly and positively related to changes in respiratory muscle blood flow (r = 0.73), whereby increasing the WOB increased blood flow. Conversely, changes in WOB were significantly and inversely related to changes in locomotor blood flow (r = 0.57), whereby decreasing the

Evidence for a Ustilago maydis Steroid 5α-Reductase by Functional Expression in Arabidopsis det2-1 Mutants1

Science.gov (United States)

Basse, Christoph W.; Kerschbamer, Christine; Brustmann, Markus; Altmann, Thomas; Kahmann, Regine

2002-01-01

We have identified a gene (udh1) in the basidiomycete Ustilago maydis that is induced during the parasitic interaction with its host plant maize (Zea mays). udh1 encodes a protein with high similarity to mammalian and plant 5α-steroid reductases. Udh1 differs from those of known 5α-steroid reductases by six additional domains, partially predicted to be membrane-spanning. A fusion protein of Udh1 and the green fluorescent protein provided evidence for endoplasmic reticulum localization in U. maydis. The function of the Udh1 protein was demonstrated by complementing Arabidopsis det2-1 mutants, which display a dwarf phenotype due to a mutation in the 5α-steroid reductase encoding DET2 gene. det2-1 mutant plants expressing either the udh1 or the DET2 gene controlled by the cauliflower mosaic virus 35S promoter differed from wild-type Columbia plants by accelerated stem growth, flower and seed development and a reduction in size and number of rosette leaves. The accelerated growth phenotype of udh1 transgenic plants was stably inherited and was favored under reduced light conditions. Truncation of the N-terminal 70 amino acids of the Udh1 protein abolished the ability to restore growth in det2-1 plants. Our results demonstrate the existence of a 5α-steroid reductase encoding gene in fungi and suggest a common ancestor between fungal, plant, and mammalian proteins. PMID:12068114

Recurrent Respiratory Papillomatosis or Laryngeal Papillomatosis

Science.gov (United States)

... Home » Health Info » Voice, Speech, and Language Recurrent Respiratory Papillomatosis or Laryngeal Papillomatosis On this page: What ... find additional information about RRP? What is recurrent respiratory papillomatosis? Recurrent respiratory papillomatosis (RRP) is a disease ...

Anaerobic respiratory growth of Vibrio harveyi, Vibrio fischeri and Photobacterium leiognathi with trimethylamine N-oxide, nitrate and fumarate: ecological implications.

Science.gov (United States)

Proctor, L M; Gunsalus, R P

2000-08-01

Two symbiotic species, Photobacterium leiognathi and Vibrio fischeri, and one non-symbiotic species, Vibrio harveyi, of the Vibrionaceae were tested for their ability to grow by anaerobic respiration on various electron acceptors, including trimethylamine N-oxide (TMAO) and dimethylsulphoxide (DMSO), compounds common in the marine environment. Each species was able to grow anaerobically with TMAO, nitrate or fumarate, but not with DMSO, as an electron acceptor. Cell growth under microaerophilic growth conditions resulted in elevated levels of TMAO reductase, nitrate reductase and fumarate reductase activity in each strain, whereas growth in the presence of the respective substrate for each enzyme further elevated enzyme activity. TMAO reductase specific activity was the highest of all the reductases. Interestingly, the bacteria-colonized light organs from the two squids, Euprymna scolopes and Euprymna morsei, and the light organ of the ponyfish, Leiognathus equus, also had high levels of TMAO reductase enzyme activity, in contrast to non-symbiotic tissues. The ability of these bacterial symbionts to support cell growth by respiration with TMAO may conceivably eliminate the competition for oxygen needed for both bioluminescence and metabolism.

Evidence that the intra-amoebal Legionella drancourtii acquired a sterol reductase gene from eukaryotes

Directory of Open Access Journals (Sweden)

Fournier Pierre-Edouard

2009-03-01

Full Text Available Abstract Background Free-living amoebae serve as a natural reservoir for some bacteria that have evolved into «amoeba-resistant» bacteria. Among these, some are strictly intra-amoebal, such as Candidatus "Protochlamydia amoebophila" (Candidatus "P. amoebophila", whose genomic sequence is available. We sequenced the genome of Legionella drancourtii (L. drancourtii, another recently described intra-amoebal bacterium. By comparing these two genomes with those of their closely related species, we were able to study the genetic characteristics specific to their amoebal lifestyle. Findings We identified a sterol delta-7 reductase-encoding gene common to these two bacteria and absent in their relatives. This gene encodes an enzyme which catalyses the last step of cholesterol biosynthesis in eukaryotes, and is probably functional within L. drancourtii since it is transcribed. The phylogenetic analysis of this protein suggests that it was acquired horizontally by a few bacteria from viridiplantae. This gene was also found in the Acanthamoeba polyphaga Mimivirus genome, a virus that grows in amoebae and possesses the largest viral genome known to date. Conclusion L. drancourtii acquired a sterol delta-7 reductase-encoding gene of viridiplantae origin. The most parsimonious hypothesis is that this gene was initially acquired by a Chlamydiales ancestor parasite of plants. Subsequently, its descendents transmitted this gene in amoebae to other intra-amoebal microorganisms, including L. drancourtii and Coxiella burnetii. The role of the sterol delta-7 reductase in prokaryotes is as yet unknown but we speculate that it is involved in host cholesterol parasitism.

Inactivity-induced respiratory plasticity: Protecting the drive to breathe in disorders that reduce respiratory neural activity☆

Science.gov (United States)

Strey, K.A.; Baertsch, N.A.; Baker-Herman, T.L.

2013-01-01

Multiple forms of plasticity are activated following reduced respiratory neural activity. For example, in ventilated rats, a central neural apnea elicits a rebound increase in phrenic and hypoglossal burst amplitude upon resumption of respiratory neural activity, forms of plasticity called inactivity-induced phrenic and hypoglossal motor facilitation (iPMF and iHMF), respectively. Here, we provide a conceptual framework for plasticity following reduced respiratory neural activity to guide future investigations. We review mechanisms giving rise to iPMF and iHMF, present new data suggesting that inactivity-induced plasticity is observed in inspiratory intercostals (iIMF) and point out gaps in our knowledge. We then survey conditions relevant to human health characterized by reduced respiratory neural activity and discuss evidence that inactivity-induced plasticity is elicited during these conditions. Understanding the physiological impact and circumstances in which inactivity-induced respiratory plasticity is elicited may yield novel insights into the treatment of disorders characterized by reductions in respiratory neural activity. PMID:23816599

A Quick Reference on Respiratory Acidosis.

Science.gov (United States)

Johnson, Rebecca A

2017-03-01

Respiratory acidosis, or primary hypercapnia, occurs when carbon dioxide production exceeds elimination via the lung and is mainly owing to alveolar hypoventilation. Concurrent increases in Paco 2 , decreases in pH and compensatory increases in blood HCO 3 - concentration are associated with respiratory acidosis. Respiratory acidosis can be acute or chronic, with initial metabolic compensation to increase HCO 3 - concentrations by intracellular buffering. Chronic respiratory acidosis results in longer lasting increases in renal reabsorption of HCO 3 - . Alveolar hypoventilation and resulting respiratory acidosis may also be associated with hypoxemia, especially evident when patients are inspiring room air (20.9% O 2 ). Copyright © 2016 Elsevier Inc. All rights reserved.

Pharmacogenetics of aldo-keto reductase 1C (AKR1C) enzymes.

Science.gov (United States)

Alshogran, Osama Y

2017-10-01

Genetic variation in metabolizing enzymes contributes to variable drug response and disease risk. Aldo-keto reductase type 1C (AKR1C) comprises a sub-family of reductase enzymes that play critical roles in the biotransformation of various drug substrates and endogenous compounds such as steroids. Several single nucleotide polymorphisms have been reported among AKR1C encoding genes, which may affect the functional expression of the enzymes. Areas covered: This review highlights and comprehensively discusses previous pharmacogenetic reports that have examined genetic variations in AKR1C and their association with disease development, drug disposition, and therapeutic outcomes. The article also provides information about the effect of AKR1C genetic variants on enzyme function in vitro. Expert opinion: The current evidence that links the effect of AKR1C gene polymorphisms to disease progression and development is inconsistent and needs further validation, despite of the tremendous knowledge available. Information about association of AKR1C genetic variants and drug efficacy, safety, and pharmacokinetics is limited, thus, future studies that advance our understanding about these relationships and their clinical relevance are needed. It is imperative to achieve consistent findings before the potential translation and adoption of AKR1C genetic variants in clinical practice.

Use of combined ion exchangers on the basis of KU-23 and KM-2p cation exchangers for purification of ammonium molybdate and tungstate solutions from phosphate, arsenate, and silicate impurities

International Nuclear Information System (INIS)

Blokhin, A.A.; Majorov, D.Yu.; Kopyrin, A.A.; Taushkanov, V.P.

2002-01-01

Using the Tracer technique ( 32 P) and elementary analysis, potentiality of using combined ionites on the basis of macroporous cation-exchange resins KU-23 or KM-2p and hydrated zirconium oxide for purification of concentrated solutions of ammonium molybdate and tungstate from phosphate-, arsenate-, and silicate-ions impurities was studied. High selectivity of the combined ionites towards impurity ions was ascertained, which permits reducing the content of impurities by a factor of 50-100 compared with the initial one [ru

History of mechanical ventilation may affect respiratory mechanics evolution in acute respiratory distress syndrome.

Science.gov (United States)

Koutsoukou, Antonia; Perraki, Helen; Orfanos, Stylianos E; Koulouris, Nikolaos G; Tromaropoulos, Andreas; Sotiropoulou, Christina; Roussos, Charis

2009-12-01

The aim of this study was to investigate the effect of mechanical ventilation (MV) before acute respiratory distress syndrome (ARDS) on subsequent evolution of respiratory mechanics and blood gases in protectively ventilated patients with ARDS. Nineteen patients with ARDS were stratified into 2 groups according to ARDS onset relative to the onset of MV: In group A (n = 11), MV was applied at the onset of ARDS; in group B (n = 8), MV had been initiated before ARDS. Respiratory mechanics and arterial blood gas were assessed in early (protectively ventilated patients with ARDS, late alteration of respiratory mechanics occurs more commonly in patients who have been ventilated before ARDS onset, suggesting that the history of MV affects the subsequent progress of ARDS even when using protective ventilation.

Respiratory diseases and their effects on respiratory function and exercise capacity.

Science.gov (United States)

Van Erck-Westergren, E; Franklin, S H; Bayly, W M

2013-05-01

Given that aerobic metabolism is the predominant energy pathway for most sports, the respiratory system can be a rate-limiting factor in the exercise capacity of fit and healthy horses. Consequently, respiratory diseases, even in mild forms, are potentially deleterious to any athletic performance. The functional impairment associated with a respiratory condition depends on the degree of severity of the disease and the equestrian discipline involved. Respiratory abnormalities generally result in an increase in respiratory impedance and work of breathing and a reduced level of ventilation that can be detected objectively by deterioration in breathing mechanics and arterial blood gas tensions and/or lactataemia. The overall prevalence of airway diseases is comparatively high in equine athletes and may affect the upper airways, lower airways or both. Diseases of the airways have been associated with a wide variety of anatomical and/or inflammatory conditions. In some instances, the diagnosis is challenging because conditions can be subclinical in horses at rest and become clinically relevant only during exercise. In such cases, an exercise test may be warranted in the evaluation of the patient. The design of the exercise test is critical to inducing the clinical signs of the problem and establishing an accurate diagnosis. Additional diagnostic techniques, such as airway sampling, can be valuable in the diagnosis of subclinical lower airway problems that have the capacity to impair performance. As all these techniques become more widely used in practice, they should inevitably enhance veterinarians' diagnostic capabilities and improve their assessment of treatment effectiveness and the long-term management of equine athletes. © 2013 EVJ Ltd.

Evaluation of constitutive iron reductase (AtFRO2 expression on mineral accumulation and distribution in soybean (Glycine max. L

Directory of Open Access Journals (Sweden)

Marta Wilton Vasconcelos

2014-04-01

Full Text Available Iron is an important micronutrient in human and plant nutrition. Adequate iron nutrition during crop production is central for assuring appropriate iron concentrations in the harvestable organs, for human food or animal feed. The whole-plant movement of iron involves several processes, including the reduction of ferric to ferrous iron at several locations throughout the plant, prior to transmembrane trafficking of ferrous iron. In this study, soybean plants that constitutively expressed the AtFRO2 iron reductase gene were analyzed for leaf iron reductase activity, as well as the effect of this transgene's expression on root, leaf, pod wall, and seed mineral concentrations. High Fe supply, in combination with the constitutive expression of AtFRO2, resulted in significantly higher concentrations of different minerals in roots (K, P, Zn, Ca, Ni, Mg and Mo, pod walls (Fe, K, P, Cu and Ni, leaves (Fe, P, Cu, Ca, Ni and Mg and seeds (Fe, Zn, Cu and Ni. Leaf and pod wall iron concentrations increased as much as 500% in transgenic plants, while seed iron concentrations only increased by 10%, suggesting that factors other than leaf and pod wall reductase activity were limiting the translocation of iron to seeds. Protoplasts isolated from transgenic leaves had three-fold higher reductase activity than controls. Expression levels of the iron storage protein, ferritin, were higher in the transgenic leaves than in wild-type, suggesting that the excess iron may be stored as ferritin in the leaves and therefore unavailable for phloem loading and delivery to the seeds. Also, citrate and malate levels in the roots and leaves of transgenic plants were significantly higher than in wild-type, suggesting that organic acid production could be related to the increased accumulation of minerals in roots, leaves and pod walls, but not in the seeds. All together, these results suggest a more ubiquitous role for the iron reductase in whole-plant mineral accumulation and

Correlation between the respiratory waveform measured using a respiratory sensor and 3D tumor motion in gated radiotherapy

International Nuclear Information System (INIS)

Tsunashima, Yoshikazu; Sakae, Takeji; Shioyama, Yoshiyuki; Kagei, Kenji; Terunuma, Toshiyuki; Nohtomi, Akihiro; Akine, Yasuyuki

2004-01-01

Purpose: The purpose of this study is to investigate the correlation between the respiratory waveform measured using a respiratory sensor and three-dimensional (3D) tumor motion. Methods and materials: A laser displacement sensor (LDS: KEYENCE LB-300) that measures distance using infrared light was used as the respiratory sensor. This was placed such that the focus was in an area around the patient's navel. When the distance from the LDS to the body surface changes as the patient breathes, the displacement is detected as a respiratory waveform. To obtain the 3D tumor motion, a biplane digital radiography unit was used. For the tumor in the lung, liver, and esophagus of 26 patients, the waveform was compared with the 3D tumor motion. The relationship between the respiratory waveform and the 3D tumor motion was analyzed by means of the Fourier transform and a cross-correlation function. Results: The respiratory waveform cycle agreed with that of the cranial-caudal and dorsal-ventral tumor motion. A phase shift observed between the respiratory waveform and the 3D tumor motion was principally in the range 0.0 to 0.3 s, regardless of the organ being measured, which means that the respiratory waveform does not always express the 3D tumor motion with fidelity. For this reason, the standard deviation of the tumor position in the expiration phase, as indicated by the respiratory waveform, was derived, which should be helpful in suggesting the internal margin required in the case of respiratory gated radiotherapy. Conclusion: Although obtained from only a few breathing cycles for each patient, the correlation between the respiratory waveform and the 3D tumor motion was evident in this study. If this relationship is analyzed carefully and an internal margin is applied, the accuracy and convenience of respiratory gated radiotherapy could be improved by use of the respiratory sensor.Thus, it is expected that this procedure will come into wider use

Synthesis, crystal structure, electrical properties, and sodium transport pathways of the new arsenate Na{sub 4}Co{sub 7}(AsO{sub 4}){sub 6}

Energy Technology Data Exchange (ETDEWEB)

Ben Smida, Youssef; Marzouki, Riadh [Université de Tunis El Manar, Laboratoire de Matériaux et Cristallochimie, Faculté des Sciences de Tunis, Campus Universitaire, 2092 Manar II, Tunis (Tunisia); Georges, Samuel [Université Grenoble Alpes, Laboratoire d’Electrochimie et de Physicochimie des Matériaux et des Interfaces LEPMI, F-38000 Grenoble (France); Kutteh, Ramzi [Bragg Institute, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, New South Wales 2234 (Australia); Avdeev, Maxim [Bragg Institute, Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, New South Wales 2234 (Australia); School of Chemistry, University of Sydney, Sydney, New South Wales 2006 (Australia); Guesmi, Abderrahmen; Zid, Mohamed Faouzi [Université de Tunis El Manar, Laboratoire de Matériaux et Cristallochimie, Faculté des Sciences de Tunis, Campus Universitaire, 2092 Manar II, Tunis (Tunisia)

2016-07-15

A new sodium cobalt (II) arsenate Na{sub 4}Co{sub 7}(AsO{sub 4}){sub 6} has been synthesized by a solid-state reaction and its crystal structure determined from single crystal X-ray diffraction data. It crystallizes in the monoclinic system, space group C2/m, with a=10.7098(9) Å, b=14.7837(9) Å, c=6.6845(7) Å, and β=105.545(9)°. The structure is described as a three-dimensional framework built up of corner-edge sharing CoO{sub 6}, CoO{sub 4} and AsO{sub 4} polyhedra, with interconnecting channels along [100] in which the Na{sup +} cations are located. The densest ceramics with relative density of 94% was obtained by ball milling and optimization of sintering temperature, and its microstructure characterized by scanning electron microscopy. The electrical properties of the ceramics were studied over a temperature interval from 280 °C to 560 °C using the complex impedance spectroscopy over the range of 13 MHz–5 Hz. The ionic bulk conductivity value of the sample at 360 °C is 2.51 10{sup −5} S cm{sup −1} and the measured activation energy is Ea=1 eV. The sodium migration pathways in the crystal structure were investigated computationally using the bond valence site energy (BVSE) model and classical molecular dynamics (MD) simulations. - Graphical abstract: Correlation between crystal structure, microstructure and ionic conductivity . Display Omitted - Highlights: • A new arsenate Na{sub 4}Co{sub 7}(AsO{sub 4}){sub 6} was prepared by solid state reaction. • Its crystal structure was determined by powder X-ray diffraction. • Na{sup +} ionic conductivity was probed by complex impedance spectroscopy. • Na{sup +} conduction pathways were modeled by bond-valence method and molecular dynamics.

Purification of a NAD(P) reductase-like protein from the thermogenic appendix of the Sauromatum guttatum inflorescence.

Science.gov (United States)

Skubatz, Hanna; Howald, William N

2013-03-01

A NAD(P) reductase-like protein with a molecular mass of 34.146 ± 34 Da was purified to homogeneity from the appendix of the inflorescence of the Sauromatum guttatum. On-line liquid chromatography/electrospray ionization-mass spectrometry was used to isolate and quantify the protein. For the identification of the protein, liquid chromatography/electrospray ionization-tandem mass spectrometry analysis of tryptic digests of the protein was carried out. The acquired mass spectra were used for database searching, which led to the identification of a single tryptic peptide. The 12 amino acid tryptic peptide (FLPSEFGNDVDR) was found to be identical to amino acid residues at the positions 108-120 of isoflavone reductase in the Arabidopsis genome. A BLAST search identified this sequence region as unique and specific to a class of NAD(P)-dependent reductases involved in phenylpropanoid biosynthesis. Edman degradation revealed that the protein was N-terminally blocked. The amount of the protein (termed RL, NAD(P) reductase-like protein) increased 60-fold from D-4 (4 days before inflorescence-opening, designated as D-day) to D-Day, and declined the following day, when heat-production ceased. When salicylic acid, the endogenous trigger of heat-production in the Sauromatum appendix, was applied to premature appendices, a fivefold decrease in the amount of RL was detected in the treated section relative to the non-treated section. About 40 % of RL was found in the cytoplasm. Another 30 % was detected in Percoll-purified mitochondria and the rest, about 30 % was associated with a low speed centrifugation pellet due to nuclei and amyloplast localization. RL was also found in other thermogenic plants and detected in Arabidopsis leaves. The function of RL in thermogenic and non-thermogenic plants requires further investigation.

Seasonality of long term wheezing following respiratory syncytial virus lower respiratory tract infection

NARCIS (Netherlands)

Bont, L.; Steijn, M.; van Aalderen, W. M. C.; Brus, F.; Th Draaisma, J. M.; van Diemen-Steenvoorde, R. A. A. M.; Pekelharing-Berghuis, M.; Kimpen, J. L. L.

2004-01-01

Background: It is well known that respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) is associated with subsequent wheezing episodes, but the precise natural course of wheezing following RSV LRTI is not known. This study aimed to determine the continuous development of

Seasonality of long term wheezing following respiratory syncytial virus lower respiratory tract infection

NARCIS (Netherlands)

Bont, L; Steijn, M; van Aalderen, WMC; Brus, F; Draaisma, JMT; Van Diemen-Steenvoorde, RAAM; Pekelharing-Berghuis, M; Kimpen, JLL

Background: It is well known that respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) is associated with subsequent wheezing episodes, but the precise natural course of wheezing following RSV LRTI is not known. This study aimed to determine the continuous development of

Sex hormones reduce NNK detoxification through inhibition of short-chain dehydrogenases/reductases and aldo-keto reductases in vitro.

Science.gov (United States)

Stapelfeld, Claudia; Maser, Edmund

2017-10-01

Carbonyl reduction is an important metabolic pathway for endogenous and xenobiotic substances. The tobacco specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK, nicotine-derived nitrosamine ketone) is classified as carcinogenic to humans (IARC, Group 1) and considered to play the most important role in tobacco-related lung carcinogenesis. Detoxification of NNK through carbonyl reduction is catalyzed by members of the AKR- and the SDR-superfamilies which include AKR1B10, AKR1C1, AKR1C2, AKR1C4, 11β-HSD1 and CBR1. Because some reductases are also involved in steroid metabolism, five different hormones were tested for their inhibitory effect on NNK carbonyl reduction. Two of those hormones were estrogens (estradiol and ethinylestradiol), another two hormones belong to the gestagen group (progesterone and drospirenone) and the last tested hormone was an androgen (testosterone). Furthermore, one of the estrogens (ethinylestradiol) and one of the gestagens (drospirenone) are synthetic hormones, used as hormonal contraceptives. Five of six NNK reducing enzymes (AKR1B10, AKR1C1, AKR1C2, AKR1C4 and 11β-HSD1) were significantly inhibited by the tested sex hormones. Only NNK reduction catalyzed by CBR1 was not significantly impaired. In the case of the other five reductases, gestagens had remarkably stronger inhibitory effects at a concentration of 25 μM (progesterone: 66-88% inhibition; drospirenone: 26-87% inhibition) in comparison to estrogens (estradiol: 17-51% inhibition; ethinylestradiol: 14-79% inhibition) and androgens (14-78% inhibition). Moreover, in most cases the synthetic hormones showed a greater ability to inhibit NNK reduction than the physiologic derivatives. These results demonstrate that male and female sex hormones have different inhibitory potentials, thus indicating that there is a varying detoxification capacity of NNK in men and women which could result in a different risk for developing lung cancer. Copyright © 2017 Elsevier B

Visual aided pacing in respiratory maneuvers

Energy Technology Data Exchange (ETDEWEB)

Rambaudi, L R [Laboratorio de Biofisica y Fisiologia ' Antonio Sadi Frumento' (Argentina); Rossi, E [Catedra de Bioingenieria II (Argentina); Mantaras, M C [Catedra de Bioingenieria II (Argentina); Perrone, M S [Laboratorio de Biofisica y Fisiologia ' Antonio Sadi Frumento' (Argentina); Siri, L Nicola [Catedra de Bioingenieria II (Argentina)

2007-11-15

A visual aid to pace self-controlled respiratory cycles in humans is presented. Respiratory manoeuvres need to be accomplished in several clinic and research procedures, among others, the studies on Heart Rate Variability. Free running respiration turns to be difficult to correlate with other physiologic variables. Because of this fact, voluntary self-control is asked from the individuals under study. Currently, an acoustic metronome is used to pace respiratory frequency, its main limitation being the impossibility to induce predetermined timing in the stages within the respiratory cycle. In the present work, visual driven self-control was provided, with separate timing for the four stages of a normal respiratory cycle. This visual metronome (ViMet) was based on a microcontroller which power-ON and -OFF an eight-LED bar, in a four-stage respiratory cycle time series handset by the operator. The precise timing is also exhibited on an alphanumeric display.

Visual aided pacing in respiratory maneuvers

International Nuclear Information System (INIS)

Rambaudi, L R; Rossi, E; Mantaras, M C; Perrone, M S; Siri, L Nicola

2007-01-01

A visual aid to pace self-controlled respiratory cycles in humans is presented. Respiratory manoeuvres need to be accomplished in several clinic and research procedures, among others, the studies on Heart Rate Variability. Free running respiration turns to be difficult to correlate with other physiologic variables. Because of this fact, voluntary self-control is asked from the individuals under study. Currently, an acoustic metronome is used to pace respiratory frequency, its main limitation being the impossibility to induce predetermined timing in the stages within the respiratory cycle. In the present work, visual driven self-control was provided, with separate timing for the four stages of a normal respiratory cycle. This visual metronome (ViMet) was based on a microcontroller which power-ON and -OFF an eight-LED bar, in a four-stage respiratory cycle time series handset by the operator. The precise timing is also exhibited on an alphanumeric display

Human respiratory syncytial virus load normalized by cell quantification as predictor of acute respiratory tract infection.

Science.gov (United States)

Gómez-Novo, Miriam; Boga, José A; Álvarez-Argüelles, Marta E; Rojo-Alba, Susana; Fernández, Ana; Menéndez, María J; de Oña, María; Melón, Santiago

2018-05-01

Human respiratory syncytial virus (HRSV) is a common cause of respiratory infections. The main objective is to analyze the prediction ability of viral load of HRSV normalized by cell number in respiratory symptoms. A prospective, descriptive, and analytical study was performed. From 7307 respiratory samples processed between December 2014 to April 2016, 1019 HRSV-positive samples, were included in this study. Low respiratory tract infection was present in 729 patients (71.54%). Normalized HRSV load was calculated by quantification of HRSV genome and human β-globin gene and expressed as log10 copies/1000 cells. HRSV mean loads were 4.09 ± 2.08 and 4.82 ± 2.09 log10 copies/1000 cells in the 549 pharyngeal and 470 nasopharyngeal samples, respectively (P respiratory tract infection and 4.22 ± 2.28 log10 copies/1000 cells with upper respiratory tract infection or febrile syndrome (P < 0.05). A possible cut off value to predict LRTI evolution was tentatively established. Normalization of viral load by cell number in the samples is essential to ensure an optimal virological molecular diagnosis avoiding that the quality of samples affects the results. A high viral load can be a useful marker to predict disease progression. © 2018 Wiley Periodicals, Inc.

Direct antioxidant properties of bilirubin andbiliverdin. Is there a role for biliverdin reductase?

Directory of Open Access Journals (Sweden)

Thomas eJansen

2012-03-01

Full Text Available Reactive oxygen species (ROS and signaling events are involved in the pathogenesis of endothelial dysfunction and represent a major contribution to vascular regulation. Molecular signaling is highly dependent on reactive oxygen species. But depending on the amount of ROS production it might have toxic or protective effects. Despite a large number of negative outcomes in large clinical trials (e.g. HOPE, HOPE-TOO, antioxidant molecules and agents are important players to influence the critical balance between production and elimination of RONS. However, chronic systemic antioxidant therapy lacks clinical efficacy, probably by interfering with important physiological redox signaling pathways. Therefore, it may be a much more promising attempt to induce intrinsic antioxidant pathways in order to increase the antioxidants not systemically but at the place of oxidative stress and complications. Among others, heme oxygenase (HO has been shown to be important for attenuating the overall production of ROS in a broad range of disease states through its ability to degrade heme and to produce carbon monoxide (CO, biliverdin/bilirubin, and the release of free iron with subsequent ferritin induction. With the present review we would like to highlight the important antioxidant role of the heme oxygenase system and especially discuss the contribution of the biliverdin, bilirubin and biliverdin reductase to these beneficial effects. The bilierdin reductase was reported to confer an antioxidant redox amplification cycle by which low, physiological bilirubin concentrations confer potent antioxidant protection via recycling of biliverdin from oxidized bilirubin by the biliverdin reductase, linking this sink for oxidants to the NADPH pool. To date the existence and role of this antioxidant redox cycle is still under debate and we present and discuss the pros and cons as well as our own findings on this topic.