Membrane toxicity of abnormal prion protein in adrenal chromaffin cells of scrapie infected sheep.

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Gillian McGovern

Full Text Available Transmissible spongiform encephalopathies (TSEs or prion diseases are associated with accumulations of disease specific PrP (PrP(d in the central nervous system (CNS and often the lymphoreticular system (LRS. Accumulations have additionally been recorded in other tissues including the peripheral nervous system and adrenal gland. Here we investigate the effect of sheep scrapie on the morphology and the accumulation of PrP(d in the adrenal medulla of scrapie affected sheep using light and electron microscopy. Using immunogold electron microscopy, non-fibrillar forms of PrP(d were shown to accumulate mainly in association with chromaffin cells, occasional nerve endings and macrophages. PrP(d accumulation was associated with distinctive membrane changes of chromaffin cells including increased electron density, abnormal linearity and invaginations. Internalisation of PrP(d from the chromaffin cell plasma membrane occurred in association with granule recycling following hormone exocytosis. PrP(d accumulation and internalisation from membranes is similarly associated with perturbations of membrane structure and trafficking in CNS neurons and tingible body macrophages of the LRS. These data suggest that a major toxic effect of PrP(d is at the level of plasma membranes. However, the precise nature of PrP(d-membrane toxicity is tissue and cell specific suggesting that the normal protein may act as a multi-functional scaffolding molecule. We further suggest that the co-localisation of PrP(d with exocytic granules of the hormone trafficking system may provide an additional source of infectivity in blood.

Discovery of Selective Inhibitors of Imidazoleglycerol-Phosphate Dehydratase from Mycobacterium tuberculosis by Virtual Screening

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Podshivalov, D.; Mandzhieva, Yu. B.; Sidorov-Biryukov, D. D.; Timofeev, V. I.; Kuranova, I. P.

2018-01-01

Bacterial imidazoleglycerol-phosphate dehydratase from Mycobacterium tuberculosis (HisB- Mt) is a convenient target for the discovery of selective inhibitors as potential antituberculosis drugs. The virtual screening was performed to find compounds suitable for the design of selective inhibitors of HisB- Mt. The positions of four ligands, which were selected based on the docking scoring function and docked to the activesite region of the enzyme, were refined by molecular dynamics simulation. The nearest environment of the ligands was determined. These compounds selectively bind to functionally essential active-site residues, thus blocking access of substrates to the active site of the enzyme, and can be used as lead compounds for the design of selective inhibitors of HisB- M.

RNAi suppression of Arogenate Dehydratase1 reveals that phenylalanine is synthesized predominantly via the arogenate pathway in petunia petals.

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Maeda, Hiroshi; Shasany, Ajit K; Schnepp, Jennifer; Orlova, Irina; Taguchi, Goro; Cooper, Bruce R; Rhodes, David; Pichersky, Eran; Dudareva, Natalia

2010-03-01

l-Phe, a protein building block and precursor of numerous phenolic compounds, is synthesized from prephenate via an arogenate and/or phenylpyruvate route in which arogenate dehydratase (ADT) or prephenate dehydratase, respectively, plays a key role. Here, we used Petunia hybrida flowers, which are rich in Phe-derived volatiles, to determine the biosynthetic routes involved in Phe formation in planta. Of the three identified petunia ADTs, expression of ADT1 was the highest in petunia petals and positively correlated with endogenous Phe levels throughout flower development. ADT1 showed strict substrate specificity toward arogenate, although with the lowest catalytic efficiency among the three ADTs. ADT1 suppression via RNA interference in petunia petals significantly reduced ADT activity, levels of Phe, and downstream phenylpropanoid/benzenoid volatiles. Unexpectedly, arogenate levels were unaltered, while shikimate and Trp levels were decreased in transgenic petals. Stable isotope labeling experiments showed that ADT1 suppression led to downregulation of carbon flux toward shikimic acid. However, an exogenous supply of shikimate bypassed this negative regulation and resulted in elevated arogenate accumulation. Feeding with shikimate also led to prephenate and phenylpyruvate accumulation and a partial recovery of the reduced Phe level in transgenic petals, suggesting that the phenylpyruvate route can also operate in planta. These results provide genetic evidence that Phe is synthesized predominantly via arogenate in petunia petals and uncover a novel posttranscriptional regulation of the shikimate pathway.

The 3-hydroxyacyl-CoA dehydratases HACD1 and HACD2 exhibit functional redundancy and are active in a wide range of fatty acid elongation pathways.

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Sawai, Megumi; Uchida, Yukiko; Ohno, Yusuke; Miyamoto, Masatoshi; Nishioka, Chieko; Itohara, Shigeyoshi; Sassa, Takayuki; Kihara, Akio

2017-09-15

Differences among fatty acids (FAs) in chain length and number of double bonds create lipid diversity. FA elongation proceeds via a four-step reaction cycle, in which the 3-hydroxyacyl-CoA dehydratases (HACDs) HACD1-4 catalyze the third step. However, the contribution of each HACD to 3-hydroxyacyl-CoA dehydratase activity in certain tissues or in different FA elongation pathways remains unclear. HACD1 is specifically expressed in muscles and is a myopathy-causative gene. Here, we generated Hacd1 KO mice and observed that these mice had reduced body and skeletal muscle weights. In skeletal muscle, HACD1 mRNA expression was by far the highest among the HACDs However, we observed only an ∼40% reduction in HACD activity and no changes in membrane lipid composition in Hacd1 -KO skeletal muscle, suggesting that some HACD activities are redundant. Moreover, when expressed in yeast, both HACD1 and HACD2 participated in saturated and monounsaturated FA elongation pathways. Disruption of HACD2 in the haploid human cell line HAP1 significantly reduced FA elongation activities toward both saturated and unsaturated FAs, and HACD1 HACD2 double disruption resulted in a further reduction. Overexpressed HACD3 exhibited weak activity in saturated and monounsaturated FA elongation pathways, and no activity was detected for HACD4. We therefore conclude that HACD1 and HACD2 exhibit redundant activities in a wide range of FA elongation pathways, including those for saturated to polyunsaturated FAs, with HACD2 being the major 3-hydroxyacyl-CoA dehydratase. Our findings are important for furthering the understanding of the molecular mechanisms in FA elongation and diversity. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Arogenate Dehydratase Isoforms Differentially Regulate Anthocyanin Biosynthesis in Arabidopsis thaliana.

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Chen, Qingbo; Man, Cong; Li, Danning; Tan, Huijuan; Xie, Ye; Huang, Jirong

2016-12-05

Anthocyanins, a group of L-phenylalanine (Phe)-derived flavonoids, have been demonstrated to play important roles in plant stress resistance and interactions between plants and insects. Although the anthocyanin biosynthetic pathway and its regulatory mechanisms have been extensively studied, it remains unclear whether the level of Phe supply affects anthocyanin biosynthesis. Here, we investigated the roles of arogenate dehydratases (ADTs), the key enzymes that catalyze the conversion of arogenate into Phe, in sucrose-induced anthocyanin biosynthesis in Arabidopsis. Genetic analysis showed that all six ADT isoforms function redundantly in anthocyanin biosynthesis but have differential contributions. ADT2 contributes the most to anthocyanin accumulation, followed by ADT1 and ADT3, and ADT4-ADT6. We found that anthocyanin content is positively correlated with the levels of Phe and sucrose-induced ADT transcripts in seedlings. Consistently, addition of Phe to the medium could dramatically increase anthocyanin content in the wild-type plants and rescue the phenotype of the adt1 adt3 double mutant regarding the anthocyanin accumulation. Moreover, transgenic plants overexpressing ADT4, which appears to be less sensitive to Phe than overexpression of ADT2, hyperaccumulate Phe and produce elevated level of anthocyanins. Taken together, our results suggest that the level of Phe is an important regulatory factor for sustaining anthocyanin biosynthesis. Copyright © 2016 The Author. Published by Elsevier Inc. All rights reserved.

Vitamin-E reduces the oxidative damage on delta-aminolevulinic dehydratase induced by lead intoxication in rat erythrocytes.

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Rendón-Ramirez, A; Cerbón-Solórzano, J; Maldonado-Vega, M; Quintanar-Escorza, M A; Calderón-Salinas, J V

2007-09-01

Lead intoxication induces oxidative damage on lipids and proteins. In the present paper we study in vivo and in vitro the antioxidant effect of vitamin-E and trolox, on the oxidative effects of lead intoxication in rat erythrocytes. Vitamin-E simultaneously administered to erythrocytes treated with lead was capable to prevent the inhibition of delta-aminolevulinic dehydratase activity and lipid oxidation. Partial but important protective effects were found when vitamin-E was administered either after or before lead exposure in rats. In vitro, the antioxidant trolox protected delta-ALA-D activity against damage induced by lead or menadione. These results indicate that vitamin-E could be useful in order to protect membrane-lipids and, notably, to prevent protein oxidation produced by lead intoxication.

Scrapie affects the maturation cycle and immune complex trapping by follicular dendritic cells in mice.

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Gillian McGovern

2009-12-01

Full Text Available Transmissible spongiform encephalopathies (TSEs or prion diseases are infectious neurological disorders of man and animals, characterised by abnormal disease-associated prion protein (PrP(d accumulations in the brain and lymphoreticular system (LRS. Prior to neuroinvasion, TSE agents often accumulate to high levels within the LRS, apparently without affecting immune function. However, our analysis of scrapie-affected sheep shows that PrP(d accumulations within the LRS are associated with morphological changes to follicular dendritic cells (FDCs and tingible body macrophages (TBMs. Here we examined FDCs and TBMs in the mesenteric lymph nodes (MLNs of scrapie-affected mice by light and electron microscopy. In MLNs from uninfected mice, FDCs could be morphologically categorised into immature, mature and regressing forms. However, in scrapie-affected MLNs this maturation cycle was adversely affected. FDCs characteristically trap and retain immune complexes on their surfaces, which they display to B-lymphocytes. In scrapie-affected MLNs, some FDCs were found where areas of normal and abnormal immune complex retention occurred side by side. The latter co-localised with PrP(d plasmalemmal accumulations. Our data suggest this previously unrecognised morphology represents the initial stage of an abnormal FDC maturation cycle. Alterations to the FDCs included PrP(d accumulation, abnormal cell membrane ubiquitin and excess immunoglobulin accumulation. Regressing FDCs, in contrast, appeared to lose their membrane-attached PrP(d. Together, these data suggest that TSE infection adversely affects the maturation and regression cycle of FDCs, and that PrP(d accumulation is causally linked to the abnormal pathology observed. We therefore support the hypothesis that TSEs cause an abnormality in immune function.

SVM-based Partial Discharge Pattern Classification for GIS

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Ling, Yin; Bai, Demeng; Wang, Menglin; Gong, Xiaojin; Gu, Chao

2018-01-01

Partial discharges (PD) occur when there are localized dielectric breakdowns in small regions of gas insulated substations (GIS). It is of high importance to recognize the PD patterns, through which we can diagnose the defects caused by different sources so that predictive maintenance can be conducted to prevent from unplanned power outage. In this paper, we propose an approach to perform partial discharge pattern classification. It first recovers the PRPD matrices from the PRPD2D images; then statistical features are extracted from the recovered PRPD matrix and fed into SVM for classification. Experiments conducted on a dataset containing thousands of images demonstrates the high effectiveness of the method.

Continuous far red irradiation controls molecular properties of delta-aminolevulinate dehydratase in Raphanus Sativus seedlings

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Balange, A.P. (Centre National de la Recherche Scientifique, 76-Mont Saint Aignan (France). Lab. de Photobiologie); Lambert, C. (U.E.R. Scientifique de Luminy, Dept. de Biologie Moleculaire et Cellulaire, Marseilles (France))

1983-12-01

8-Aminolevulinate dehydratase (EC 4.2.1.24) (ALAD) is a phytochrome-dependent enzyme. Under continuous far red light (FR), the intracellular location of ALAD is modified: in young irradiated seedling cotyledons (48 h from sowing) it is localised in the cytoplasm, as for seedlings kept in continuous darkness or irradiated but treated with erythromycin (ERT). In seedlings kept 120 h under continuous FR light, ALAD is detected in cytoplasm too, but also in etioplasts. Studies from DEAE-cellulose chromatography show that, when ALAD is localised in the cytoplasm it has a stable charge, but an unstable molecular weight. If plastids are allowed to grow normally under continuous FR light, the enzyme can be purified from stroma of etioplasts from 72 h from sowing. The molecule is unstable, both in charge and in molecular weight. ALAD from etioplasts is further transformed into a species stable both in charge and in molecular weight. The relationship between the molecular modifications and physiological results observed previously are discussed. 12 refs.

Computation-Facilitated Assignment of Function in the Enolase Superfamily: A Regiochemically Distinct Galactarate Dehydratase from Oceanobacillus iheyensis†

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Rakus, John F.; Kalyanaraman, Chakrapani; Fedorov, Alexander A.; Fedorov, Elena V.; Mills-Groninger, Fiona P.; Toro, Rafael; Bonanno, Jeffrey; Bain, Kevin; Sauder, J. Michael; Burley, Stephen K.; Almo, Steven C.; Jacobson, Matthew P.; Gerlt, John A.

2009-01-01

The structure of an uncharacterized member of the enolase superfamily from Oceanobacillus iheyensis (GI: 23100298; IMG locus tag Ob2843; PDB Code 2OQY) was determined by the New York SGX Research Center for Structural Genomics (NYSGXRC). The structure contained two Mg2+ ions located 10.4 Å from one another, with one located in the canonical position in the (β/α)7β-barrel domain (although the ligand at the end of the fifth β-strand is His, unprecedented in structurally characterized members of the superfamily); the second is located in a novel site within the capping domain. In silico docking of a library of mono- and diacid sugars to the active site predicted a diacid sugar as a likely substrate. Activity screening of a physical library of acid sugars identified galactarate as the substrate (kcat = 6.8 s−1, KM = 620 μM; kcat/KM = 1.1 × 104 M−1 s−1), allowing functional assignment of Ob2843 as galactarate dehydratase (GalrD-II) The structure of a complex of the catalytically impaired Y90F mutant with Mg2+ and galactarate allowed identification of a Tyr 164-Arg 162 dyad as the base that initiates the reaction by abstraction of the α-proton and Tyr 90 as the acid that facilitates departure of the β-OH leaving group. The enzyme product is 2-keto-3-deoxy-D-threo-4,5-dihydroxyadipate, the enantiomer of the product obtained in the GalrD reaction catalyzed by a previously characterized bifunctional L-talarate/galactarate dehydratase (TalrD/GalrD). On the basis of the different active site structures and different regiochemistries, we recognize that these functions represent an example of apparent, not actual, convergent evolution of function. The structure of GalrD-II and its active site architecture allow identification of the seventh functionally and structurally characterized subgroup in the enolase superfamily. This study provides an additional example that an integrated sequence/structure-based strategy employing computational approaches is a viable

Root exudate-induced alterations in Bacillus cereus cell wall contribute to root colonization and plant growth promotion.

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Swarnalee Dutta

Full Text Available The outcome of an interaction between plant growth promoting rhizobacteria and plants may depend on the chemical composition of root exudates (REs. We report the colonization of tobacco, and not groundnut, roots by a non-rhizospheric Bacillus cereus (MTCC 430. There was a differential alteration in the cell wall components of B. cereus in response to the REs from tobacco and groundnut. Attenuated total reflectance infrared spectroscopy revealed a split in amide I region of B. cereus cells exposed to tobacco-root exudates (TRE, compared to those exposed to groundnut-root exudates (GRE. In addition, changes in exopolysaccharides and lipid-packing were observed in B. cereus grown in TRE-amended minimal media that were not detectable in GRE-amended media. Cell-wall proteome analyses revealed upregulation of oxidative stress-related alkyl hydroperoxide reductase, and DNA-protecting protein chain (Dlp-2, in response to GRE and TRE, respectively. Metabolism-related enzymes like 2-amino-3-ketobutyrate coenzyme A ligase and 2-methylcitrate dehydratase and a 60 kDa chaperonin were up-regulated in response to TRE and GRE. In response to B. cereus, the plant roots altered their exudate-chemodiversity with respect to carbohydrates, organic acids, alkanes, and polyols. TRE-induced changes in surface components of B. cereus may contribute to successful root colonization and subsequent plant growth promotion.

Lead Effect on Aminolevulinic Acid Dehydratase Activity of Feral Pigeon (Columba livia in Drenas

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Albana Plakiqi Milaimi

2015-09-01

Full Text Available This study was aimed to investigate the effects of environmental pollution with heavy metals from ferro-nickel smelter on Aminolevulinic Acid Dehydratase (ALAD activity, and to analyze the blood lead level of feral pigeon (Columba livia in ferro-nickel smelter courtyard in Drenas City, Republic of Kosovo. For this purpose, twenty specimens of feral pigeon (20 birds, males and females, were collected in Drenas city which were living in ferro-nickel smelter courtyard, and 20 specimens in Lubizhdë village as control group (non-contaminated area. ALAD activity in Drenas group was significantly inhibited (P<0.001, compared with ALAD activity of controls. The blood lead level was significantly increased (P=0.015 compared to control group. Correlation between ALAD and blood lead level in Drenas group was negative (r=-0.117; P>0.050 and positive in Lubizhdë group (r=0.452; P> 0.050, but not in significant difference between the input groups. Feral pigeons can play an important role as bioindicators, which can used to monitor the environmental pollution with heavy metals that may originate from Nickel metallurgy.

Scrapie-specific pathology of sheep lymphoid tissues.

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Gillian McGovern

Full Text Available Transmissible spongiform encephalopathies (TSEs or prion diseases often result in accumulation of disease-associated PrP (PrP(d in the lymphoreticular system (LRS, specifically in association with follicular dendritic cells (FDCs and tingible body macrophages (TBMs of secondary follicles. We studied the effects of sheep scrapie on lymphoid tissue in tonsils and lymph nodes by light and electron microscopy. FDCs of sheep were grouped according to morphology as immature, mature or regressing. Scrapie was associated with FDC dendrite hypertrophy and electron dense deposit or vesicles. PrP(d was located using immunogold labelling at the plasmalemma of FDC dendrites and, infrequently, mature B cells. Abnormal electron dense deposits surrounding FDC dendrites were identified as immunoglobulins suggesting that excess immune complexes are retained and are indicative of an FDC dysfunction. Within scrapie-affected lymph nodes, macrophages outside the follicle and a proportion of germinal centre TBMs accumulated PrP(d within endosomes and lysosomes. In addition, TBMs showed PrP(d in association with the cell membrane, non-coated pits and vesicles, and also with discrete, large and random endoplasmic reticulum networks, which co-localised with ubiquitin. These observations suggest that PrP(d is internalised via the caveolin-mediated pathway, and causes an abnormal disease-related alteration in endoplasmic reticulum structure. In contrast to current dogma, this study shows that sheep scrapie is associated with cytopathology of germinal centres, which we attribute to abnormal antigen complex trapping by FDCs and abnormal endocytic events in TBMs. The nature of the sub-cellular changes in FDCs and TBMs differs from those of scrapie infected neurones and glial cells suggesting that different PrP(d/cell membrane interactions occur in different cell types.

Modulation of δ-Aminolevulinic Acid Dehydratase Activity by the Sorbitol-Induced Osmotic Stress in Maize Leaf Segments.

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Jain, M; Tiwary, S; Gadre, R

2018-01-01

Osmotic stress induced with 1 M sorbitol inhibited δ-aminolevulinic acid dehydratase (ALAD) and aminolevulinic acid (ALA) synthesizing activities in etiolated maize leaf segments during greening; the ALAD activity was inhibited to a greater extent than the ALA synthesis. When the leaves were exposed to light, the ALAD activity increased for the first 8 h, followed by a decrease observed at 16 and 24 h in both sorbitol-treated and untreated leaf tissues. The maximum inhibition of the enzyme activity was observed in the leaf segments incubated with sorbitol for 4 to 8 h. Glutamate increased the ALAD activity in the in vitro enzymatic preparations obtained from the sorbitol-treated leaf segments; sorbitol inhibited the ALAD activity in the preparations from both sorbitol-treated and untreated leaves. It was suggested that sorbitol-induced osmotic stress inhibits the enzyme activity by affecting the ALAD induction during greening and regulating the ALAD steady-state level of ALAD in leaf cells. The protective effect of glutamate on ALAD in the preparations from the sorbitol-treated leaves might be due to its stimulatory effect on the enzyme.

Liver δ-Aminolevulinate Dehydratase Activity is Inhibited by Neonicotinoids and Restored by Antioxidant Agents

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Elisa Sauer

2014-11-01

Full Text Available Neonicotinoids represent the most used class of insecticides worldwide, and their precursor, imidacloprid, is the most widely marketed. The aim of this study was to evaluate the effect of imidacloprid on the activity of hepatic δ-aminolevulinate dehydratase (δ-ALA-D, protective effect of potential antioxidants against this potential effect and presence of chemical elements in the constitution of this pesticide. We observed that δ-ALA-D activity was significantly inhibited by imidacloprid at all concentrations tested in a dose-dependent manner. The IC50 value was obtained and used to evaluate the restoration of the enzymatic activity. δ-ALA-D inhibition was completely restored by addition of dithiotreitol (DTT and partly by ZnCl2, demonstrating that the inhibition occurs by oxidation of thiol groups and by displacement of the Zn (II, which can be explained by the presence of chemical elements found in the constitution of pesticides. Reduced glutathione (GSH had the best antioxidant effect against to δ-ALA-D inhibition caused by imidacloprid, followed by curcumin and resveratrol. It is well known that inhibition of the enzyme δ-ALA-D may result in accumulation of its neurotoxic substrate (δ-ALA, in this line, our results suggest that further studies are needed to investigate the possible neurotoxicity induced by neonicotinoids and the involvement of antioxidants in cases of poisoning by neonicotinoids.

Delta-aminolevulinate dehydratase activity and oxidative stress markers in preeclampsia.

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de Lucca, Leidiane; Rodrigues, Fabiane; Jantsch, Letícia B; Kober, Helena; Neme, Walter S; Gallarreta, Francisco M P; Gonçalves, Thissiane L

2016-12-01

Preeclampsia is an important pregnancy-specific multisystem disorder characterized by the onset of hypertension and proteinuria. It is of unknown etiology and involves serious risks for the pregnant women and fetus. One of the main factors involved in the pathophysiology of preeclampsia is oxidative stress, where excess free radicals produce harmful effects, including damage to macromolecules such as lipids, proteins and DNA. In addition, the sulfhydryl delta-aminolevulinate dehydratase enzyme (δ-ALA-D) that is part of the heme biosynthetic pathway in pro-oxidant conditions can be inhibited, which may result in the accumulation of 5-aminolevulinic acid (ALA), associated with the overproduction of free radicals, suggesting it to be an indirect marker of oxidative stress. As hypertensive pregnancy complications are a major cause of morbidity and mortality maternal and fetal where oxidative stress appears to be an important factor involved in preeclampsia, the aim of this study was to evaluate the activity of δ-ALA-D and classic oxidative stress markers in the blood of pregnant women with mild and severe preeclampsia. The analysis and quantification of the following oxidative stress markers were performed: thiobarbituric acid-reactive species (TBARS); presence of protein and non-protein thiol group; quantification of vitamin C; Catalase and δ-ALA--D activities in samples of blood of pregnant women with mild preeclampsia (n=25), with severe preeclampsia (n=30) and in a control group of healthy pregnant women (n=30). TBARS was significantly higher in women with preeclampsia, while the presence of thiol groups, levels of vitamin C, catalase and δ-ALA-D activity were significantly lower in groups of pregnant women with preeclampsia compared with healthy women. In addition, the results showed no significant difference between groups of pregnant women with mild and severe preeclampsia. The data suggest a state of increased oxidative stress in pregnant women with

Negative regulation by Ser/Thr phosphorylation of HadAB and HadBC dehydratases from Mycobacterium tuberculosis type II fatty acid synthase system.

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Slama, Nawel; Leiba, Jade; Eynard, Nathalie; Daffé, Mamadou; Kremer, Laurent; Quémard, Annaïk; Molle, Virginie

2011-09-02

The type II fatty acid synthase system of mycobacteria is involved in the biosynthesis of major and essential lipids, mycolic acids, key-factors of Mycobacterium tuberculosis pathogenicity. One reason of the remarkable survival ability of M. tuberculosis in infected hosts is partly related to the presence of cell wall-associated mycolic acids. Despite their importance, the mechanisms that modulate synthesis of these lipids in response to environmental changes are unknown. We demonstrate here that HadAB and HadBC dehydratases of this system are phosphorylated by Ser/Thr protein kinases, which negatively affects their enzymatic activity. The phosphorylation of HadAB/BC is growth phase-dependent, suggesting that it represents a mechanism by which mycobacteria might tightly control mycolic acid biosynthesis under non-replicating condition. Copyright © 2011 Elsevier Inc. All rights reserved.

Evolution of Enzymatic Activities in the Enolase Superfamily: L-Rhamnonate Dehydratase

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Rakus,J.; Fedorov, A.; Fedorov, E.; Glaner, M.; Hubbard, B.; Delli, J.; Babbitt, P.; Almo, S.; Gerlt, J.

2008-01-01

The l-rhamnonate dehydratase (RhamD) function was assigned to a previously uncharacterized family in the mechanistically diverse enolase superfamily that is encoded by the genome of Escherichia coli K-12. We screened a library of acid sugars to discover that the enzyme displays a promiscuous substrate specificity: l-rhamnonate (6-deoxy-l-mannonate) has the 'best' kinetic constants, with l-mannonate, l-lyxonate, and d-gulonate dehydrated less efficiently. Crystal structures of the RhamDs from both E. coli K-12 and Salmonella typhimurium LT2 (95% sequence identity) were obtained in the presence of Mg2+; the structure of the RhamD from S. typhimurium was also obtained in the presence of 3-deoxy-l-rhamnonate (obtained by reduction of the product with NaBH4). Like other members of the enolase superfamily, RhamD contains an N-terminal a + {beta} capping domain and a C-terminal ({beta}/a)7{beta}-barrel (modified TIM-barrel) catalytic domain with the active site located at the interface between the two domains. In contrast to other members, the specificity-determining '20s loop' in the capping domain is extended in length and the '50s loop' is truncated. The ligands for the Mg2+ are Asp 226, Glu 252 and Glu 280 located at the ends of the third, fourth and fifth {beta}-strands, respectively. The active site of RhamD contains a His 329-Asp 302 dyad at the ends of the seventh and sixth {beta}-strands, respectively, with His 329 positioned to function as the general base responsible for abstraction of the C2 proton of l-rhamnonate to form a Mg2+-stabilized enediolate intermediate. However, the active site does not contain other acid/base catalysts that have been implicated in the reactions catalyzed by other members of the MR subgroup of the enolase superfamily. Based on the structure of the liganded complex, His 329 also is expected to function as the general acid that both facilitates departure of the 3-OH group in a syn-dehydration reaction and

The Aspergillus fumigatus dihydroxyacid dehydratase Ilv3A/IlvC is required for full virulence.

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Jason D Oliver

Full Text Available Dihydroxyacid dehydratase (DHAD is a key enzyme in the branched-chain amino acid biosynthetic pathway that exists in a variety of organisms, including fungi, plants and bacteria, but not humans. In this study we identified four putative DHAD genes from the filamentous fungus Aspergillus fumigatus by homology to Saccharomyces cerevisiae ILV3. Two of these genes, AFUA_2G14210 and AFUA_1G03550, initially designated AfIlv3A and AfIlv3B for this study, clustered in the same group as S. cerevisiae ILV3 following phylogenetic analysis. To investigate the functions of these genes, AfIlv3A and AfIlv3B were knocked out in A. fumigatus. Deletion of AfIlv3B gave no apparent phenotype whereas the Δilv3A strain required supplementation with isoleucine and valine for growth. Thus, AfIlv3A is required for branched-chain amino acid synthesis in A. fumigatus. A recombinant AfIlv3A protein derived from AFUA_2G14210 was shown to have DHAD activity in an in vitro assay, confirming that AfIlv3A is a DHAD. In addition we show that mutants lacking AfIlv3A and ilv3B exhibit reduced levels of virulence in murine infection models, emphasising the importance of branched-chain amino acid biosynthesis in fungal infections, and hence the potential of targeting this pathway with antifungal agents. Here we propose that AfIlv3A/AFUA_2G2410 be named ilvC.

Two different zinc sites in bovine 5-aminolevulinate dehydratase distinguished by extended x-ray absorption fine structure

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Dent, A.J.; Hasnain, S.S.; Beyersmann, D.; Block, C.

1990-01-01

The zinc coordination in 5-aminolevulinate dehydratase was investigated by extended x-ray absorption fine structure (EXAFS) associated with the zinc K-edge. The enzyme binds 8 mol of zinc/mol of octameric protein, but only four zinc ions seem sufficient for full activity. The authors have undertaken a study on four forms of the enzyme: (a) the eight-zinc native enzyme; (b) the enzyme with only the four zinc sites necessary for full activation occupied; (c) the enzyme with the vacant sites of (b) occupied by four lead ions; (d) the product complex between (b) and porphobilinogen. They have shown that two structurally distinct types of zinc sites are available in the enzyme. The site necessary for activity has an average zinc environment best described by two/three histidines and one/zero oxygen from a group such as tyrosine or a solvent molecule at 2.06 ± 0.02 angstrom, one tyrosine or aspartate at 1.91 ± 0.03 angstrom, and one cysteine sulfur at 2.32 ± 0.03 angstrom with a total coordination of five ligands. The unoccupied site in (b) is dominated by a single contribution of four cysteinyl sulfur atoms at 2.28 ± 0.02 angstrom. Spectra from samples (c) and (d) show only small changes from that of (b), reflecting a slight rearrangement of the ligands around the zinc atom

Identification and characterization of trans-3-hydroxy-l-proline dehydratase and Δ1-pyrroline-2-carboxylate reductase involved in trans-3-hydroxy-l-proline metabolism of bacteria

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Seiya Watanabe

2014-01-01

Full Text Available trans-4-Hydroxy-l-proline (T4LHyp and trans-3-hydroxy-l-proline (T3LHyp occur mainly in collagen. A few bacteria can convert T4LHyp to α-ketoglutarate, and we previously revealed a hypothetical pathway consisting of four enzymes at the molecular level (J Biol Chem (2007 282, 6685–6695; J Biol Chem (2012 287, 32674–32688. Here, we first found that Azospirillum brasilense has the ability to grow not only on T4LHyp but also T3LHyp as a sole carbon source. In A. brasilense cells, T3LHyp dehydratase and NAD(PH-dependent Δ1-pyrroline-2-carboxylate (Pyr2C reductase activities were induced by T3LHyp (and d-proline and d-lysine but not T4LHyp, and no effect of T3LHyp was observed on the expression of T4LHyp metabolizing enzymes: a hypothetical pathway of T3LHyp → Pyr2C → l-proline was proposed. Bacterial T3LHyp dehydratase, encoded to LhpH gene, was homologous with the mammalian enzyme. On the other hand, Pyr2C reductase encoded to LhpI gene was a novel member of ornithine cyclodeaminase/μ-crystallin superfamily, differing from known bacterial protein. Furthermore, the LhpI enzymes of A. brasilense and another bacterium showed several different properties, including substrate and coenzyme specificities. T3LHyp was converted to proline by the purified LhpH and LhpI proteins. Furthermore, disruption of LhpI gene from A. brasilense led to loss of growth on T3LHyp, d-proline and d-lysine, indicating that this gene has dual metabolic functions as a reductase for Pyr2C and Δ1-piperidine-2-carboxylate in these pathways, and that the T3LHyp pathway is not linked to T4LHyp and l-proline metabolism.

Biomonitoring of lead-contaminated Missouri streams with an assay for erythrocyte δ-aminolevulinic acid dehydratase activity in fish blood

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Schmitt, C.J.; Wildhaber, M.L.; Hunn, J.B.; Nash, T.; Tieger, M. N.; Steadman, B. L.

1993-01-01

The activity of the enzyme δ-aminolevulinic acid dehydratase (ALA-D) in erythrocytes has long been used as a biomarker of lead exposure in humans and waterfowl and, more recently, in fishes. The assay was tested for ALA-D activity in fishes from streams affected by lead in combination with other metals from lead-zinc mining and related activities. Fishes (mostly catostomids) were collected from sites affected by historic and current mining activities, and from sites considered to be unaffected by mining (reference sites). A group of potentially toxic elements was measured in blood and carcass samples of individual fish, as were ALA-D activity, total protein (TP), and hemoglobin (Hb) in blood. Concentrations of mining-related metals (lead, zinc, and cadmium) were significantly greater (P<0.05) in fish blood and carcass at sites affected by historic mining activities than at reference and active mining sites. When analyzed by multiple regression, ALA-D activity, Hb, and TP accounted for 66% of blood-lead and 69% of carcass-lead variability. Differences among species were small. ALA-D activity as a biomarker adequately distinguished sites affected by bioavailable environmental lead. Zinc was the only other metal that affected ALA-D activity; it appeared to ameliorate the inactivation of ALA-D by lead.

Blood Lead Level and Δ-Aminolevulinic Acid Dehydratase Activity in Pre-Menopausal and Postmenopausal Women

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I.R Elezaj

2012-07-01

Full Text Available To describe the relationship of blood lead levels (BLL and blood, δ-aminolevulinic acid dehydratase(ALAD activity and haematocrit value(Hct to menopause , were examined 17 pre-or perimenopausal (PreM and 17 postmenopausal women (PosMfrom Prishtina City, the capital ofRepublic Kosovo. The mean age of the PreM women was 28.8 years (21-46, with a mean blood lead level of 1.2 μg/dL (SD=0.583 μg/dL , the mean blood ALAD activity53.2 U/LE (SD= 2.8 U/LE and haematocrit value42.1 % (SD= 4.3 %. The mean age of the PosM women was 53.6 years (43-67, with a mean blood lead level1.9 μg/dL (SD=0.94 μg/dL, the mean blood ALAD activity 44.4 U/LE(SD=7.2 U/LE and haematocrit value 42.1 % ( SD= 4.3 % and 42.2 % (SD=4.4 %. The BPb level of PosM women was significantly higher (P<0.001 in comparison with the BPb level in PreM women. The blood ALAD activity of PosM was significantly inhibited (P<0.002 in comparison with blood ALAD activity in PreM women. The haematocrit values were relatively unchanged. There was established significantly negative correlation between BPb and blood ALAD activity (r=- 0.605; P<0.01 in the PreM women.These results support the hypothesis that release of bone lead stores increases during menopause and constitutes an internal source of exposure possibly associated with adverse health effects on women in menopause transition.

Homology modeling and virtual screening to discover potent inhibitors targeting the imidazole glycerophosphate dehydratase protein in Staphylococcus xylosus

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Chen, Xing-Ru; Wang, Xiao-Ting; Hao, Mei-Qi; Zhou, Yong-Hui; Cui, Wen-Qiang; Xing, Xiao-Xu; Xu, Chang-Geng; Bai, Jing-Wen; Li, Yan-Hua

2017-11-01

The imidazole glycerophosphate dehydratase (IGPD) protein is a therapeutic target for herbicide discovery. It is also regarded as a possible target in Staphylococcus xylosus (S. xylosus) for solving mastitis in the dairy cow. The 3D structure of IGPD protein is essential for discovering novel inhibitors during high-throughput virtual screening. However, to date, the 3D structure of IGPD protein of S. xylosus has not been solved. In this study, a series of computational techniques including homology modeling, Ramachandran Plots, and Verify 3D were performed in order to construct an appropriate 3D model of IGPD protein of S. xylosus. Nine hits were identified from 2500 compounds by docking studies. Then, these 9 compounds were first tested in vitro in S. xylosus biofilm formation using crystal violet staining. One of the potential compounds, baicalin was shown to significantly inhibit S. xylosus biofilm formation. Finally, the baicalin was further evaluated, which showed better inhibition of biofilm formation capability in S. xylosus by scanning electron microscopy. Hence, we have predicted the structure of IGPD protein of S. xylosus using computational techniques. We further discovered the IGPD protein was targeted by baicalin compound which inhibited the biofilm formation in S. xylosus. Our findings here would provide implications for the further development of novel IGPD inhibitors for the treatment of dairy mastitis.

Expression of a bacterial 3-dehydroshikimate dehydratase reduces lignin content and improves biomass saccharification efficiency.

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Eudes, Aymerick; Sathitsuksanoh, Noppadon; Baidoo, Edward E K; George, Anthe; Liang, Yan; Yang, Fan; Singh, Seema; Keasling, Jay D; Simmons, Blake A; Loqué, Dominique

2015-12-01

Lignin confers recalcitrance to plant biomass used as feedstocks in agro-processing industries or as source of renewable sugars for the production of bioproducts. The metabolic steps for the synthesis of lignin building blocks belong to the shikimate and phenylpropanoid pathways. Genetic engineering efforts to reduce lignin content typically employ gene knockout or gene silencing techniques to constitutively repress one of these metabolic pathways. Recently, new strategies have emerged offering better spatiotemporal control of lignin deposition, including the expression of enzymes that interfere with the normal process for cell wall lignification. In this study, we report that expression of a 3-dehydroshikimate dehydratase (QsuB from Corynebacterium glutamicum) reduces lignin deposition in Arabidopsis cell walls. QsuB was targeted to the plastids to convert 3-dehydroshikimate - an intermediate of the shikimate pathway - into protocatechuate. Compared to wild-type plants, lines expressing QsuB contain higher amounts of protocatechuate, p-coumarate, p-coumaraldehyde and p-coumaryl alcohol, and lower amounts of coniferaldehyde, coniferyl alcohol, sinapaldehyde and sinapyl alcohol. 2D-NMR spectroscopy and pyrolysis-gas chromatography/mass spectrometry (pyro-GC/MS) reveal an increase of p-hydroxyphenyl units and a reduction of guaiacyl units in the lignin of QsuB lines. Size-exclusion chromatography indicates a lower degree of lignin polymerization in the transgenic lines. Therefore, our data show that the expression of QsuB primarily affects the lignin biosynthetic pathway. Finally, biomass from these lines exhibits more than a twofold improvement in saccharification efficiency. We conclude that the expression of QsuB in plants, in combination with specific promoters, is a promising gain-of-function strategy for spatiotemporal reduction of lignin in plant biomass. © 2015 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The

Evaluation of erythrocyte delta-amino levulinic acid dehydratase activity as a short-term indicator in fish of a harmful exposure to lead

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Hodson, P.V.; Blunt, B.R.; Spry, D.J.; Austen, K.

1977-04-01

The activity of erythrocyte delta-amino levulinic acid dehydratase (ALA-D) of fish is easily measured under a variety of experimental conditions. Exposure of rainbow trout (Salmo gairdneri), brook trout (Salvelinus fontinalis), goldfish (Carassius auratus), and pumpkinseeds (Lepomis gibbosus) to lead consistently inhibited ALA-D within 2 wks at concentrations as low as 10, 90, 470, and 90 ..mu..g/l, respectively. In rainbow and brook trout these concentrations were closely related to the published minimum effective concentrations causing sublethal harm. There was a significant linear relationship between ALA-D activity and log of blood lead concentration, between ALA-D activity and log of lead in water, and between blood lead and lead in water. Near lethal exposures to cadmium, copper, zinc, and mercury did not significantly inhibit ALA-D activity. Recovery of ALA-D activity of rainbow trout after transfer from 120 ..mu..g/l lead to clean water occurred in 8 wk. This enzyme provides fast, consistent, specific, and sensitive estimates of lead concentrations causing sublethal harm to fish and may help to relate sources of lead to degree of exposure of fish populations in the field.

Cumulative Effect of Depression on Dementia Risk

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J. Olazarán

2013-01-01

Full Text Available Objective. To analyze a potential cumulative effect of life-time depression on dementia and Alzheimer’s disease (AD, with control of vascular factors (VFs. Methods. This study was a subanalysis of the Neurological Disorders in Central Spain (NEDICES study. Past and present depression, VFs, dementia status, and dementia due to AD were documented at study inception. Dementia status was also documented after three years. Four groups were created according to baseline data: never depression (nD, past depression (pD, present depression (prD, and present and past depression (prpD. Logistic regression was used. Results. Data of 1,807 subjects were investigated at baseline (mean age 74.3, 59.3% women, and 1,376 (81.6% subjects were evaluated after three years. The prevalence of dementia at baseline was 6.7%, and dementia incidence was 6.3%. An effect of depression was observed on dementia prevalence (OR [CI 95%] 1.84 [1.01–3.35] for prD and 2.73 [1.08–6.87] for prpD, and on dementia due to AD (OR 1.98 [0.98–3.99] for prD and OR 3.98 [1.48–10.71] for prpD (fully adjusted models, nD as reference. Depression did not influence dementia incidence. Conclusions. Present depression and, particularly, present and past depression are associated with dementia at old age. Multiple mechanisms, including toxic effect of depression on hippocampal neurons, plausibly explain these associations.

New function of aldoxime dehydratase: Redox catalysis and the formation of an unexpected product.

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Yamada, Masatoshi; Hashimoto, Yoshiteru; Kumano, Takuto; Tsujimura, Seiya; Kobayashi, Michihiko

2017-01-01

In general, hemoproteins are capable of catalyzing redox reactions. Aldoxime dehydratase (OxdA), which is a unique heme-containing enzyme, catalyzes the dehydration of aldoximes to the corresponding nitriles. Its reaction is a rare example of heme directly activating an organic substrate, unlike the utilization of H2O2 or O2 as a mediator of catalysis by other heme-containing enzymes. While it is unknown whether OxdA catalyzes redox reactions or not, we here for the first time detected catalase activity (which is one of the redox activities) of wild-type OxdA, OxdA(WT). Furthermore, we constructed a His320 → Asp mutant of OxdA [OxdA(H320D)], and found it exhibits catalase activity. Determination of the kinetic parameters of OxdA(WT) and OxdA(H320D) revealed that their Km values for H2O2 were similar to each other, but the kcat value of OxdA(H320D) was 30 times higher than that of OxdA(WT). Next, we examined another redox activity and found it was the peroxidase activity of OxdAs. While both OxdA(WT) and OxdA(H320D) showed the activity, the activity of OxdA(H320D) was dozens of times higher than that of OxdA(WT). These findings demonstrated that the H320D mutation enhances the peroxidase activity of OxdA. OxdAs (WT and H320D) were found to catalyze another redox reaction, a peroxygenase reaction. During this reaction of OxdA(H320D) with 1-methoxynaphthalene as a substrate, surprisingly, the reaction mixture changed to a color different from that with OxdA(WT), which was due to the known product, Russig's blue. We purified and identified the new product as 1-methoxy-2-naphthalenol, which has never been reported as a product of the peroxygenase reaction, to the best of our knowledge. These findings indicated that the H320D mutation not only enhanced redox activities, but also significantly altered the hydroxylation site of the substrate.

New function of aldoxime dehydratase: Redox catalysis and the formation of an unexpected product.

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Masatoshi Yamada

Full Text Available In general, hemoproteins are capable of catalyzing redox reactions. Aldoxime dehydratase (OxdA, which is a unique heme-containing enzyme, catalyzes the dehydration of aldoximes to the corresponding nitriles. Its reaction is a rare example of heme directly activating an organic substrate, unlike the utilization of H2O2 or O2 as a mediator of catalysis by other heme-containing enzymes. While it is unknown whether OxdA catalyzes redox reactions or not, we here for the first time detected catalase activity (which is one of the redox activities of wild-type OxdA, OxdA(WT. Furthermore, we constructed a His320 → Asp mutant of OxdA [OxdA(H320D], and found it exhibits catalase activity. Determination of the kinetic parameters of OxdA(WT and OxdA(H320D revealed that their Km values for H2O2 were similar to each other, but the kcat value of OxdA(H320D was 30 times higher than that of OxdA(WT. Next, we examined another redox activity and found it was the peroxidase activity of OxdAs. While both OxdA(WT and OxdA(H320D showed the activity, the activity of OxdA(H320D was dozens of times higher than that of OxdA(WT. These findings demonstrated that the H320D mutation enhances the peroxidase activity of OxdA. OxdAs (WT and H320D were found to catalyze another redox reaction, a peroxygenase reaction. During this reaction of OxdA(H320D with 1-methoxynaphthalene as a substrate, surprisingly, the reaction mixture changed to a color different from that with OxdA(WT, which was due to the known product, Russig's blue. We purified and identified the new product as 1-methoxy-2-naphthalenol, which has never been reported as a product of the peroxygenase reaction, to the best of our knowledge. These findings indicated that the H320D mutation not only enhanced redox activities, but also significantly altered the hydroxylation site of the substrate.

New function of aldoxime dehydratase: Redox catalysis and the formation of an expected product

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Kumano, Takuto; Tsujimura, Seiya; Kobayashi, Michihiko

2017-01-01

In general, hemoproteins are capable of catalyzing redox reactions. Aldoxime dehydratase (OxdA), which is a unique heme-containing enzyme, catalyzes the dehydration of aldoximes to the corresponding nitriles. Its reaction is a rare example of heme directly activating an organic substrate, unlike the utilization of H2O2 or O2 as a mediator of catalysis by other heme-containing enzymes. While it is unknown whether OxdA catalyzes redox reactions or not, we here for the first time detected catalase activity (which is one of the redox activities) of wild-type OxdA, OxdA(WT). Furthermore, we constructed a His320 → Asp mutant of OxdA [OxdA(H320D)], and found it exhibits catalase activity. Determination of the kinetic parameters of OxdA(WT) and OxdA(H320D) revealed that their Km values for H2O2 were similar to each other, but the kcat value of OxdA(H320D) was 30 times higher than that of OxdA(WT). Next, we examined another redox activity and found it was the peroxidase activity of OxdAs. While both OxdA(WT) and OxdA(H320D) showed the activity, the activity of OxdA(H320D) was dozens of times higher than that of OxdA(WT). These findings demonstrated that the H320D mutation enhances the peroxidase activity of OxdA. OxdAs (WT and H320D) were found to catalyze another redox reaction, a peroxygenase reaction. During this reaction of OxdA(H320D) with 1-methoxynaphthalene as a substrate, surprisingly, the reaction mixture changed to a color different from that with OxdA(WT), which was due to the known product, Russig’s blue. We purified and identified the new product as 1-methoxy-2-naphthalenol, which has never been reported as a product of the peroxygenase reaction, to the best of our knowledge. These findings indicated that the H320D mutation not only enhanced redox activities, but also significantly altered the hydroxylation site of the substrate. PMID:28410434

Evolution of Enzymatic Activities in the Enolase Superfamily: L-Fuconate Dehydratase from Xanthomonas campestris

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Yew,W.; Fedorov, A.; Fedorov, E.; Rakus, J.; Pierce, R.; Almo, S.; Gerlt, J.

2006-01-01

Many members of the mechanistically diverse enolase superfamily have unknown functions. In this report the authors use both genome (operon) context and screening of a library of acid sugars to assign the L-fuconate dehydratase (FucD) function to a member of the mandelate racemase (MR) subgroup of the superfamily encoded by the Xanthomonas campestris pv. campestris str. ATCC 33913 genome (GI: 21233491). Orthologues of FucD are found in both bacteria and eukaryotes, the latter including the rTS beta protein in Homo sapiens that has been implicated in regulating thymidylate synthase activity. As suggested by sequence alignments and confirmed by high-resolution structures in the presence of active site ligands, FucD and MR share the same active site motif of functional groups: three carboxylate ligands for the essential Mg2+ located at the ends of th third, fourth, and fifth-strands in the (/)7-barrel domain (Asp 248, Glu 274, and Glu 301, respectively), a Lys-x-Lys motif at the end of the second-strand (Lys 218 and Lys 220), a His-Asp dyad at the end of the seventh and sixth-strands (His 351 and Asp 324, respectively), and a Glue at the end of the eighth-strand (Glu 382). The mechanism of the FucD reaction involves initial abstraction of the 2-proton by Lys 220, acid catalysis of the vinylogous-elimination of the 3-OH group by His 351, and stereospecific ketonization of the resulting 2-keto-3-deoxy-L-fuconate product. Screening of the library of acid sugars revealed substrate and functional promiscuity: In addition to L-fuconate, FucD also catalyzes the dehydration of L-galactonate, D-arabinonate, D-altronate, L-talonate, and D-ribonate. The dehydrations of L-fuconate, L-galactonate, and D-arabinonate are initiated by abstraction of the 2-protons by Lys 220. The dehydrations of L-talonate and D-ribonate are initiated by abstraction of the 2-protons by His 351; however, protonation of the enediolate intermediates by the conjugate acid of Lys 220 yields L

Biochemical and Functional Studies on the Burkholderia cepacia Complex bceN Gene, Encoding a GDP-D-Mannose 4,6-Dehydratase

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Pinheiro, Pedro F.; Leitão, Jorge H.

2013-01-01

This work reports the biochemical and functional analysis of the Burkholderia cenocepacia J2315 bceN gene, encoding a protein with GDP-D-mannose 4,6-dehydratase enzyme activity (E.C.4.2.1.47). Data presented indicate that the protein is active when in the tetrameric form, catalyzing the conversion of GDP-D-mannose into GDP-4-keto-6-deoxy-D-mannose. This sugar nucleotide is the intermediary necessary for the biosynthesis of GDP-D-rhamnose, one of the sugar residues of cepacian, the major exopolysaccharide produced by environmental and human, animal and plant pathogenic isolates of the Burkholderia cepacia complex species. Vmax and Km values of 1.5±0.2 µmol.min−1.mg−1 and 1024±123 µM, respectively, were obtained from the kinetic characterization of the B. cenocepacia J2315 BceN protein by NMR spectroscopy, at 25°C and in the presence of 1 mol MgCl2 per mol of protein. The enzyme activity was strongly inhibited by the substrate, with an estimated Ki of 2913±350 µM. The lack of a functional bceN gene in a mutant derived from B. cepacia IST408 slightly reduced cepacian production. However, in the B. multivorans ATCC17616 with bceN as the single gene in its genome with predicted GMD activity, a bceN mutant did not produce cepacian, indicating that this gene product is required for cepacian biosynthesis. PMID:23460819

Biochemical and functional studies on the Burkholderia cepacia complex bceN gene, encoding a GDP-D-mannose 4,6-dehydratase.

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Sílvia A Sousa

Full Text Available This work reports the biochemical and functional analysis of the Burkholderia cenocepacia J2315 bceN gene, encoding a protein with GDP-D-mannose 4,6-dehydratase enzyme activity (E.C.4.2.1.47. Data presented indicate that the protein is active when in the tetrameric form, catalyzing the conversion of GDP-D-mannose into GDP-4-keto-6-deoxy-D-mannose. This sugar nucleotide is the intermediary necessary for the biosynthesis of GDP-D-rhamnose, one of the sugar residues of cepacian, the major exopolysaccharide produced by environmental and human, animal and plant pathogenic isolates of the Burkholderia cepacia complex species. Vmax and Km values of 1.5±0.2 µmol.min(-1.mg(-1 and 1024±123 µM, respectively, were obtained from the kinetic characterization of the B. cenocepacia J2315 BceN protein by NMR spectroscopy, at 25°C and in the presence of 1 mol MgCl2 per mol of protein. The enzyme activity was strongly inhibited by the substrate, with an estimated Ki of 2913±350 µM. The lack of a functional bceN gene in a mutant derived from B. cepacia IST408 slightly reduced cepacian production. However, in the B. multivorans ATCC17616 with bceN as the single gene in its genome with predicted GMD activity, a bceN mutant did not produce cepacian, indicating that this gene product is required for cepacian biosynthesis.

Aldoxime dehydratase: probing the heme environment involved in the synthesis of the carbon-nitrogen triple bond.

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Pinakoulaki, Eftychia; Koutsoupakis, Constantinos; Sawai, Hitomi; Pavlou, Andrea; Kato, Yasuo; Asano, Yasuhisa; Aono, Shigetoshi

2011-11-10

Fourier transform infrared (FTIR) spectra, "light" minus "dark" difference FTIR spectra, and time-resolved step-scan (TRS(2)) FTIR spectra are reported for carbonmonoxy aldoxime dehydratase. Two C-O modes of heme at 1945 and 1964 cm(-1) have been identified and remained unchanged in H(2)O/D(2)O exchange and in the pH 5.6-8.5 range, suggesting the presence of two conformations at the active site. The observed C-O frequencies are 5 and 16 cm(-1) lower and higher, respectively, than that obtained previously (Oinuma, K.-I.; et al. FEBS Lett.2004, 568, 44-48). We suggest that the strength of the Fe-His bond and the neutralization of the negatively charged propionate groups modulate the ν(Fe-CO)/ν(CO) back-bonding correlation. The "light" minus "dark" difference FTIR spectra indicate that the heme propionates are in both the protonated and deprotonated forms, and the photolyzed CO becomes trapped within a ligand docking site (ν(CO) = 2138 cm(-1)). The TRS(2)-FTIR spectra show that the rate of recombination of CO to the heme is k(1945 cm(-1)) = 126 ± 20 s(-1) and k(1964 cm(-1)) = 122 ± 20 s(-1) at pH 5.6, and k(1945 cm(-1)) = 148 ± 30 s(-1) and k(1964 cm(-1)) = 158 ± 32 s(-1) at pH 8.5. The rate of decay of the heme propionate vibrations is on a time scale coincident with the rate of rebinding, suggesting that there is a coupling between ligation dynamics in the distal heme environment and the environment sensed by the heme propionates. The implications of these results with respect to the proximal His-Fe heme environment including the propionates and the positively charged or proton-donating residues in the distal pocket which are crucial for the synthesis of nitriles are discussed.

[Inhibition rate of gamma-aminolevulinic acid dehydratase activity in erythrocytes as a reliable index for individual workers of low lead exposure].

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Hirano, H; Omichi, M; Ohishi, H; Ishikawa, K; Hirashima, N

1983-09-01

As the delta-aminolevulinic acid dehydratase (ALAD) activity in erythrocytes is decreased by lead exposure, we considered that a net reduction of ALAD activity by lead in blood should be the difference between the activity fully activated with zinc (Zn2+) and dithiothreitol (DTT) and that without activation. The optimal condition of activation of ALAD was found by addition of 0.25 mM of Zn2+ and 10 mM of DTT in the reaction mixture. Judging from our previous results that the amount of inhibition of ALAD activity can be represented as the rate of inhibition and is closely correlated with the dose of lead administered to rabbits, the inhibition rate of ALAD activity and lead content in blood (Pb-B) of lead workers were measured. The scatter diagram obtained from the inhibition rate and lead content in blood has two groups being divided at 50 micrograms/ml of Pb-B. In one group less than 50 micrograms/100 ml of Pb-B, the inhibition rate has been closely related to Pb-B., the regression equation being Y = 1.82 X + 11.7, and the correlation coefficient + 0.926. In another group more than 50 micrograms/100 ml of Pb-B the inhibition rate remained constant at the 90% level. Measurement of the inhibition rate suggests to have practical validity for monitoring lead exposure in workers, and by means of a nomograph lead content in blood can be estimated from the inhibition rate.

Correlation of cellular factors and differential scrapie prion permissiveness in ovine microglia

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Prion diseases are fatal neurodegenerative disorders by which the native cellular prion protein (PrP-C) is misfolded into an accumulating, disease-associated isoform (PrP-D). To improve the understanding of prion pathogenesis and develop effective treatments, it is essential to elucidate factors con...

Disturbance Elimination for Partial Discharge Detection in the Spacer of Gas-Insulated Switchgears

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Guoming Wang

2017-11-01

Full Text Available With the increasing demand for precise condition monitoring and diagnosis of gas-insulated switchgears (GISs, it has become a challenge to improve the detection sensitivity of partial discharge (PD induced in the GIS spacer. This paper deals with the elimination of the capacitive component from the phase-resolved partial discharge (PRPD signal generated in GIS spacers based on discrete wavelet transform (WT. Three types of typical insulation defects were simulated using PD cells. The single PD pulses were detected and were further used to determine the optimal mother wavelet. As a result, the bior6.8 was selected to decompose the PD signal into 8 levels and the signal energy at each level was calculated. The decomposed components related with capacitive disturbance were discarded, whereas those associated with PD were de-noised by a threshold and a thresholding function. Finally, the PRPD signals were reconstructed using the de-noised components.

Clinical features in prion protein-deficient and wild-type cattle inoculated with transmissible mink encephalopathy (TME)

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Background: Transmissible spongiform encephalopathies (TSEs) or prion diseases are caused by the propagation of a misfolded form (PrP**d) of the normal cellular prion protein, PrP**c. Recently, we have reported the generation and characterization of PrP**C-deficient cattle (PrP-/-) produced by a seq...

Effects of gallic acid on delta - aminolevulinic dehydratase activity and in the biochemical, histological and oxidative stress parameters in the liver and kidney of diabetic rats.

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de Oliveira, Lizielle Souza; Thomé, Gustavo Roberto; Lopes, Thauan Faccin; Reichert, Karine Paula; de Oliveira, Juliana Sorraila; da Silva Pereira, Aline; Baldissareli, Jucimara; da Costa Krewer, Cristina; Morsch, Vera Maria; Chitolina Schetinger, Maria Rosa; Spanevello, Roselia Maria

2016-12-01

Diabetes mellitus (DM) is characterised by hyperglycaemia associated with the increase of oxidative stress. Gallic acid has potent antioxidant properties. The aim of this study was to evaluate the effect of gallic acid on the biochemical, histological and oxidative stress parameters in the liver and kidney of diabetic rats. Male rats were divided in groups: control, gallic acid, diabetic and diabetic plus gallic acid. DM was induced in the animals by intraperitoneal injection of streptozotocin (65mg/kg). Gallic acid (30mg/kg) was administered orally for 21days. Our results showed an increase in reactive species levels and lipid peroxidation, and a decrease in activity of the enzymes superoxide dismutase and delta-aminolevulinic acid dehydratase in the liver and kidney of the diabetic animals (PGallic acid treatment showed protective effects in these parameters evaluated, and also prevented a decrease in the activity of catalase and glutathione S-transferase, and vitamin C levels in the liver of diabetic rats. In addition, gallic acid reduced the number of nuclei and increased the area of the core in hepatic tissue, and increased the glomerular area in renal tissue. These results indicate that gallic acid can protect against oxidative stress-induced damage in the diabetic state. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Chemical Modification of a Dehydratase Enzyme Involved in Bacterial Virulence by an Ammonium Derivative: Evidence of its Active Site Covalent Adduct.

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González-Bello, Concepción; Tizón, Lorena; Lence, Emilio; Otero, José M; van Raaij, Mark J; Martinez-Guitian, Marta; Beceiro, Alejandro; Thompson, Paul; Hawkins, Alastair R

2015-07-29

The first example of an ammonium derivative that causes a specific modification of the active site of type I dehydroquinase (DHQ1), a dehydratase enzyme that is a promising target for antivirulence drug discovery, is described. The resolution at 1.35 Å of the crystal structure of DHQ1 from Salmonella typhi chemically modified by this ammonium derivative revealed that the ligand is covalently attached to the essential Lys170 through the formation of an amine. The detection by mass spectroscopy of the reaction intermediates, in conjunction with the results of molecular dynamics simulations, allowed us to explain the inhibition mechanism and the experimentally observed differences between S. typhi and Staphylococcus aureus enzymes. The results presented here reveal that the replacement of Phe225 in St-DHQ1 by Tyr214 in Sa-DHQ1 and its hydrogen bonding interaction with the conserved water molecule observed in several crystal structures protects the amino adduct against further dehydration/aromatization reactions. In contrast, for the St-DHQ1 enzyme, the carboxylate group of Asp114, with the assistance of this water molecule, would trigger the formation of a Schiff base that can undergo further dehydration reactions until full aromatization of the cyclohexane ring is achieved. Moreover, in vitro antivirulence studies showed that the reported compound is able to reduce the ability of Salmonella Enteritidis to kill A459 respiratory cells. These studies have identified a good scaffold for the design of irreversible inhibitors that can be used as drugs and has opened up new opportunities for the development of novel antivirulence agents by targeting the DHQ1 enzyme.

Application of affinity propagation algorithm based on manifold distance for transformer PD pattern recognition

Science.gov (United States)

Wei, B. G.; Huo, K. X.; Yao, Z. F.; Lou, J.; Li, X. Y.

2018-03-01

It is one of the difficult problems encountered in the research of condition maintenance technology of transformers to recognize partial discharge (PD) pattern. According to the main physical characteristics of PD, three models of oil-paper insulation defects were set up in laboratory to study the PD of transformers, and phase resolved partial discharge (PRPD) was constructed. By using least square method, the grey-scale images of PRPD were constructed and features of each grey-scale image were 28 box dimensions and 28 information dimensions. Affinity propagation algorithm based on manifold distance (AP-MD) for transformers PD pattern recognition was established, and the data of box dimension and information dimension were clustered based on AP-MD. Study shows that clustering result of AP-MD is better than the results of affinity propagation (AP), k-means and fuzzy c-means algorithm (FCM). By choosing different k values of k-nearest neighbor, we find clustering accuracy of AP-MD falls when k value is larger or smaller, and the optimal k value depends on sample size.

Isolation and amino acid sequence of a dehydratase acting on d-erythro-3-hydroxyaspartate from Pseudomonas sp. N99, and its application in the production of optically active 3-hydroxyaspartate.

Science.gov (United States)

Nagano, Hiroyuki; Shibano, Kana; Matsumoto, Yu; Yokota, Atsushi; Wada, Masaru

2017-06-01

An enzyme catalyzing the ammonia-lyase reaction for the conversion of d-erythro-3-hydroxyaspartate to oxaloacetate was purified from the cell-free extract of a soil-isolated bacterium Pseudomonas sp. N99. The enzyme exhibited ammonia-lyase activity toward l-threo-3-hydroxyaspartate and d-erythro-3-hydroxyaspartate, but not toward other 3-hydroxyaspartate isomers. The deduced amino acid sequence of the enzyme, which belongs to the serine/threonine dehydratase family, shows similarity to the sequence of l-threo-3-hydroxyaspartate ammonia-lyase (EC 4.3.1.16) from Pseudomonas sp. T62 (74%) and Saccharomyces cerevisiae (64%) and serine racemase from Schizosaccharomyces pombe (65%). These results suggest that the enzyme is similar to l-threo-3-hydroxyaspartate ammonia-lyase from Pseudomonas sp. T62, which does not act on d-erythro-3-hydroxyaspartate. We also then used the recombinant enzyme expressed in Escherichia coli to produce optically pure l-erythro-3-hydroxyaspartate and d-threo-3-hydroxyaspartate from the corresponding dl-racemic mixtures. The enzymatic resolution reported here is one of the simplest and the first enzymatic method that can be used for obtaining optically pure l-erythro-3-hydroxyaspartate.

Delta-aminolevulinic acid dehydratase (ALAD) polymorphism in lead exposed Bangladeshi children and its effect on urinary aminolevulinic acid (ALA)

Energy Technology Data Exchange (ETDEWEB)

Tasmin, Saira, E-mail: rimzim1612@yahoo.com [Department of Human Ecology, School of International Health, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Furusawa, Hana [Department of Human Ecology, School of International Health, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Ahmad, Sk. Akhtar [Department of Occupational and Environmental Health, Bangladesh Institute of Health Sciences, 125/1, Darus Salam, Mirpur, Dhaka 1216 (Bangladesh); Faruquee, M.H. [Department of Public Health, State University of Bangladesh, 77 Satmasjid Road, Dhanmondi, Dhaka 1205 (Bangladesh); Watanabe, Chiho [Department of Human Ecology, School of International Health, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2015-01-15

Background and objective: Lead has long been recognized as a harmful environmental pollutant. People in developing countries like Bangladesh still have a higher risk of lead exposure. Previous research has suggested that the delta-aminolevulinic acid dehydratase (ALAD) genotype can modify lead toxicity and individual susceptibility. As children are more susceptible to lead-induced toxicity, this study investigated whether the ALAD genotype influenced urinary excretion of delta-aminolevulinic acid (U-ALA) among children exposed to environmental lead in Bangladesh. Methods: Subjects were elementary schoolchildren from a semi-urban industrialized area in Bangladesh. A total of 222 children were studied. Blood and urine were collected to determine ALAD genotypes, blood lead levels and urinary aminolevulinic acid (U-ALA). Results: The mean BPb level was 9.7 µg/dl for the study children. BPb was significantly positively correlated with hemoglobin (p<0.01). In total, allele frequency for ALAD 1 and 2 was 0.83 and 0.17 respectively. The mean U-ALA concentration was lower in ALAD1-2/2-2 carriers than ALAD1-1 carriers for boys (p=0.001). But for girls, U-ALA did not differ significantly by genotype (p=0.26). When U-ALA was compared by genotype at the same exposure level in a multiple linear regression analysis, boys who were ALAD1-2/2-2 carriers still had a lower level of U-ALA compared to ALAD1-1carriers. Conclusion: This study provides information about the influence of ALAD polymorphism and its association with U-ALA in Bangladeshi children. Our results indicate that the ALAD1-2/2-2 genotype may have a protective effect in terms of U-ALA for environmentally lead exposed boys. - Highlights: • High blood lead level for the environmentally exposed schoolchildren. • BPb was significantly correlated with U-ALA and Hb. • Effect of ALAD genotype on U-ALA is differed by sex. • Lower U-ALA in ALAD2 than ALAD1 carriers only for boys at same exposure.

Etude de l'equation de Navier-Stokes stochastique non homogene

African Journals Online (AJOL)

Prp;,u + Prp(uV)u-Pr~u Prpf (4). Cette equation jointe a la condition (S) peut se substituer au systeme d'equations ((1 )-(2)). u~0e~. ~. Si la force exterieure est soumise a une perturbation stochastique, alors on considere l'equation stochastique suivante: Prpdu.+ (Prp(uV)u-Prv.Au)dt=Prpfdt. +PrpdG. Dans notte 6tude, cette ...

Prion-seeding activity in cerebrospinal fluid of deer with chronic wasting disease.

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Nicholas J Haley

Full Text Available Transmissible spongiform encephalopathies (TSEs, or prion diseases, are a uniformly fatal family of neurodegenerative diseases in mammals that includes chronic wasting disease (CWD of cervids. The early and ante-mortem identification of TSE-infected individuals using conventional western blotting or immunohistochemistry (IHC has proven difficult, as the levels of infectious prions in readily obtainable samples, including blood and bodily fluids, are typically beyond the limits of detection. The development of amplification-based seeding assays has been instrumental in the detection of low levels of infectious prions in clinical samples. In the present study, we evaluated the cerebrospinal fluid (CSF of CWD-exposed (n=44 and naïve (n=4 deer (n=48 total for CWD prions (PrP(d using two amplification assays: serial protein misfolding cyclic amplification with polytetrafluoroethylene beads (sPMCAb and real-time quaking induced conversion (RT-QuIC employing a truncated Syrian hamster recombinant protein substrate. Samples were evaluated blindly in parallel with appropriate positive and negative controls. Results from amplification assays were compared to one another and to obex immunohistochemistry, and were correlated to available clinical histories including CWD inoculum source (e.g. saliva, blood, genotype, survival period, and duration of clinical signs. We found that both sPMCAb and RT-QuIC were capable of amplifying CWD prions from cervid CSF, and results correlated well with one another. Prion seeding activity in either assay was observed in approximately 50% of deer with PrP(d detected by IHC in the obex region of the brain. Important predictors of amplification included duration of clinical signs and time of first tonsil biopsy positive results, and ultimately the levels of PrP(d identified in the obex by IHC. Based on our findings, we expect that both sPMCAb and RT-QuIC may prove to be useful detection assays for the detection of prions in

High voltage diagnostics on electrical insulation of supersonducting magnets

International Nuclear Information System (INIS)

Irmisch, M.

1995-12-01

The high voltage (HV) performance of superconducting magnets of large dimensions, e.g. as needed in fusion reactors, is a challange in the field of high voltage technology, i.e. especially in the field of cryogenic high voltage components and with respect to questions of HV insulation diagnostics at low temperature. By using the development of POLO - a superconducting prototype coil of a tokamak poloidal field coil - as an example, this work deals with special problems of how to get use of conventional HV test techniques for diagnostics under special cryogenic boundary conditions. As a first approach to gain experience in the field of phase resolved partial discharge (PRPD) measurements during operation of a superconductive coil, the POLO coil was subject to several high voltage tests. Compared with DC insulation resistance measurements and capacitive impulse voltage discharges to the coil, the AC PD measurements have been the only way to observe special characteristics of the electrical insulation with respect to the cooling down of the coil from 300 K to 4.2 K. The PRPD measurement technique thereby has proofed as a suitable diagnostic tool. This work can serve as basic data to be comparable within further projects of electrical insulation diagnostics at cryogenic temperatures. (orig.)

Immunophenotype of cells within cervine rectoanal mucosa-associated lymphoid tissue and mesenteric lymph nodes.

Science.gov (United States)

Dagleish, M P; Finlayson, J; Steele, P J; Pang, Y; Hamilton, S; Eaton, S L; Sales, J; González, L; Chianini, F

2012-05-01

Rectoanal mucosa-associated lymphoid tissue (RAMALT) is a part of the lymphoid system that can be sampled easily in live animals, especially ruminants. RAMALT biopsy is useful for the diagnosis of transmissible spongiform encephalopathies, including scrapie in sheep and goats and chronic wasting disease (CWD) in cervids. Diagnosis is reliant on detection of abnormal prion protein (PrP(d)), which is associated with lymphoid follicles. For enzyme linked immunosorbent assays (ELISAs) detecting PrP(d) it is necessary to ensure that lymphoid follicles are present in biopsy samples to avoid false-negative results. Monoclonal antibodies known to recognize specific immune cell subsets present in lymphoid tissues of sheep were tested for cross-reactivity with cervine RAMALT and mesenteric lymph nodes (MLNs) preserved in zinc salts fixative. The distribution of cells expressing CD3, CD4, CD79, CD21 and class II molecules of the major histocompatibility complex was determined in these tissues. Cells of each immunophenotype had similar distributions in RAMALT and MLNs and these distributions were similar to those reported previously for sheep and cattle. The identification and validation of cervine lymphoid follicle cell markers (CD79 and CD21) may allow reduction in false-negative results during diagnosis of CWD by ELISA. Copyright © 2011 Elsevier Ltd. All rights reserved.

Dual Fatty Acid Elongase Complex Interactions in Arabidopsis

Science.gov (United States)

Morineau, Céline; Gissot, Lionel; Bellec, Yannick; Hematy, Kian; Tellier, Frédérique; Renne, Charlotte; Haslam, Richard; Beaudoin, Frédéric; Napier, Johnathan; Faure, Jean-Denis

2016-01-01

Very long chain fatty acids (VLCFAs) are involved in plant development and particularly in several cellular processes such as membrane trafficking, cell division and cell differentiation. However, the precise role of VLCFAs in these different cellular processes is still poorly understood in plants. In order to identify new factors associated with the biosynthesis or function of VLCFAs, a yeast multicopy suppressor screen was carried out in a yeast mutant strain defective for fatty acid elongation. Loss of function of the elongase 3 hydroxyacyl-CoA dehydratase PHS1 in yeast and PASTICCINO2 in plants prevents growth and induces cytokinesis defects. PROTEIN TYROSIN PHOSPHATASE-LIKE (PTPLA) previously characterized as an inactive dehydratase was able to restore yeast phs1 growth and VLCFAs elongation but not the plant pas2-1 defects. PTPLA interacted with elongase subunits in the Endoplasmic Reticulum (ER) and its absence induced the accumulation of 3-hydroxyacyl-CoA as expected from a dehydratase involved in fatty acid (FA) elongation. However, loss of PTPLA function increased VLCFA levels, an effect that was dependent on the presence of PAS2 indicating that PTPLA activity repressed FA elongation. The two dehydratases have specific expression profiles in the root with PAS2, mostly restricted to the endodermis, while PTPLA was confined in the vascular tissue and pericycle cells. Comparative ectopic expression of PTPLA and PAS2 in their respective domains confirmed the existence of two independent elongase complexes based on PAS2 or PTPLA dehydratase that are functionally interacting. PMID:27583779

Intraperitoneal Infection of Wild-Type Mice with Synthetically Generated Mammalian Prion.

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Xinhe Wang

2015-07-01

Full Text Available The prion hypothesis postulates that the infectious agent in transmissible spongiform encephalopathies (TSEs is an unorthodox protein conformation based agent. Recent successes in generating mammalian prions in vitro with bacterially expressed recombinant prion protein provide strong support for the hypothesis. However, whether the pathogenic properties of synthetically generated prion (rec-Prion recapitulate those of naturally occurring prions remains unresolved. Using end-point titration assay, we showed that the in vitro prepared rec-Prions have infectious titers of around 104 LD50/μg. In addition, intraperitoneal (i.p. inoculation of wild-type mice with rec-Prion caused prion disease with an average survival time of 210-220 days post inoculation. Detailed pathological analyses revealed that the nature of rec-Prion induced lesions, including spongiform change, disease specific prion protein accumulation (PrP-d and the PrP-d dissemination amongst lymphoid and peripheral nervous system tissues, the route and mechanisms of neuroinvasion were all typical of classical rodent prions. Our results revealed that, similar to naturally occurring prions, the rec-Prion has a titratable infectivity and is capable of causing prion disease via routes other than direct intra-cerebral challenge. More importantly, our results established that the rec-Prion caused disease is pathogenically and pathologically identical to naturally occurring contagious TSEs, supporting the concept that a conformationally altered protein agent is responsible for the infectivity in TSEs.

Metal Accumulation, Blood δ-Aminolevulinic Acid Dehydratase Activity and Micronucleated Erythrocytes of Feral pigeons (Columba Livia Living Near Former Lead-Zinc Smelter “ Trepça” – Kosovo

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Elezaj I. R.

2013-04-01

Full Text Available The concentration of lead in blood and tibia (Pb, zinc (Zn and cupper (Cu in tibia, blood δ- aminolevulinic acid dehydratase (ALA-D; EC: 4.2.1.24 activity, hematocrit value (Hct and micronuclei frequency (MN of peripheral erythrocytes have been determinated in three different populations of feral pigeons (Columba livia; forma urbana and forma domestica, collected in Mitrovica town (situated close to smelter “Trepça”, down closed in 2000 year and in rural area (Koshare willage . The blood lead level in feral pigeons from Mitrovica (forma urbana was 3 times higher (149.6; 50.5 μg% in comparison with that in feral pigeons from Mitrovica (forma domestica and 27.7 times higher (5.4 μg% in comparison with pigeons from rural area. The Pb concentration of tibia of feral pigeons (froma urbana and forma domestica, from Mitrovica town was significantly higher (P<0.001 in comparison with control. The concentration of Zn in tibia of feral pigeons from Mitrovica town (forma urbana, was significantly higher (P<0.006 in comparison with control. The blood ALA-D activity of feral pigeons from Mitrovica town (forma urbana and froma domestica, was significantly inhibited in comparison with control. The blood ALA-D activity of feral pigeons –forma urbana from Mitrovica town was significantly inhibited (P<0.001 in comparison with the blood ALA-D activity of feral pigeons-forma domestica from Mitrovica town. The erythrocyte MN frequency of feral pigeons from Mitrovica was significantly higher (P <0.001 in comparison with controls. The smelter “Trepça” ten year after closed down pose a threat to the local environment, biota and people’s health.

Arabidopsis and Maize RidA Proteins Preempt Reactive Enamine/Imine Damage to Branched-Chain Amino Acid Biosynthesis in Plastids[C][W][OPEN

Science.gov (United States)

Niehaus, Thomas D.; Nguyen, Thuy N.D.; Gidda, Satinder K.; ElBadawi-Sidhu, Mona; Lambrecht, Jennifer A.; McCarty, Donald R.; Downs, Diana M.; Cooper, Arthur J.L.; Fiehn, Oliver; Mullen, Robert T.; Hanson, Andrew D.

2014-01-01

RidA (for Reactive Intermediate Deaminase A) proteins are ubiquitous, yet their function in eukaryotes is unclear. It is known that deleting Salmonella enterica ridA causes Ser sensitivity and that S. enterica RidA and its homologs from other organisms hydrolyze the enamine/imine intermediates that Thr dehydratase forms from Ser or Thr. In S. enterica, the Ser-derived enamine/imine inactivates a branched-chain aminotransferase; RidA prevents this damage. Arabidopsis thaliana and maize (Zea mays) have a RidA homolog that is predicted to be plastidial. Expression of either homolog complemented the Ser sensitivity of the S. enterica ridA mutant. The purified proteins hydrolyzed the enamines/imines formed by Thr dehydratase from Ser or Thr and protected the Arabidopsis plastidial branched-chain aminotransferase BCAT3 from inactivation by the Ser-derived enamine/imine. In vitro chloroplast import assays and in vivo localization of green fluorescent protein fusions showed that Arabidopsis RidA and Thr dehydratase are chloroplast targeted. Disrupting Arabidopsis RidA reduced root growth and raised the root and shoot levels of the branched-chain amino acid biosynthesis intermediate 2-oxobutanoate; Ser treatment exacerbated these effects in roots. Supplying Ile reversed the root growth defect. These results indicate that plastidial RidA proteins can preempt damage to BCAT3 and Ile biosynthesis by hydrolyzing the Ser-derived enamine/imine product of Thr dehydratase. PMID:25070638

Risk of Visual Impairment and Intracranial Hypertension After Space Flight: Evaluation of the Role of Polymorphism of Enzymes Involved in One-Carbon Metabolism

Science.gov (United States)

Smith, S. M.; Gregory, J. F.; Zeisel, G. H.; Gibson, C. R.; Mader, T. H.; Kinchen, J.; Ueland, P.; Ploutz-Snyder, R.; Heer, M.; Zwart, S. R.

2016-01-01

Data from the Nutritional Status Assessment protocol provided biochemical evidence that the one-carbon metabolic pathway may be altered in individuals experiencing vision-related issues during and after space flight (1, 2). Briefly, serum concentrations of homocysteine, cystathionine, 2-methylcitric acid, and methylmalonic acid were significantly (P<0.001) higher (25-45%) in astronauts with ophthalmic changes than in those without such changes (1). These differences existed before, during, and after flight. Serum folate was lower (P<0.01) during flight in individuals with ophthalmic changes. Preflight serum concentrations of cystathionine and 2-methylcitric acid, and mean in-flight serum folate, were significantly (P<0.05) correlated with postflight changes in refraction (1). A follow-up study was conducted to evaluate a small number of known polymorphisms of enzymes in the one-carbon pathway, and to evaluate how these relate to vision and other medical aspects of the eye. Specifically, we investigated 5 polymorphisms in MTRR, MTHFR, SHMT, and CBS genes and their association with ophthalmic changes after flight in 49 astronauts. The number of G alleles of MTRR 66 and C alleles of SHMT1 1420 both contributed to the odds of visual disturbances (3). Block regression showed that B-vitamin status at landing and genetics were significant predictors for many of the ophthalmic outcomes studied (3). In conclusion, we document an association between MTRR 66 and SHMT1 1420 polymorphisms and space flightinduced vision changes. These data document that individuals with an altered 1-carbon metabolic pathway may be predisposed to anatomic and/or physiologic changes that render them susceptible to ophthalmic damage during space flight.

Structural studies of substrate and product complexes of 5-aminolaevulinic acid dehydratase from humans, Escherichia coli and the hyperthermophile Pyrobaculum calidifontis.

Science.gov (United States)

Mills-Davies, N; Butler, D; Norton, E; Thompson, D; Sarwar, M; Guo, J; Gill, R; Azim, N; Coker, A; Wood, S P; Erskine, P T; Coates, L; Cooper, J B; Rashid, N; Akhtar, M; Shoolingin-Jordan, P M

2017-01-01

A number of X-ray analyses of an enzyme involved in a key early stage of tetrapyrrole biosynthesis are reported. Two structures of human 5-aminolaevulinate dehydratase (ALAD), native and recombinant, have been determined at 2.8 Å resolution, showing that the enzyme adopts an octameric quaternary structure in accord with previously published analyses of the enzyme from a range of other species. However, this is in contrast to the finding that a disease-related F12L mutant of the human enzyme uniquely forms hexamers [Breinig et al. (2003), Nature Struct. Biol. 10, 757-763]. Monomers of all ALADs adopt the TIM-barrel fold; the subunit conformation that assembles into the octamer includes the N-terminal tail of one monomer curled around the (α/β) 8 barrel of a neighbouring monomer. Both crystal forms of the human enzyme possess two monomers per asymmetric unit, termed A and B. In the native enzyme there are a number of distinct structural differences between the A and B monomers, with the latter exhibiting greater disorder in a number of loop regions and in the active site. In contrast, the second monomer of the recombinant enzyme appears to be better defined and the active site of both monomers clearly possesses a zinc ion which is bound by three conserved cysteine residues. In native human ALAD, the A monomer also has a ligand resembling the substrate ALA which is covalently bound by a Schiff base to one of the active-site lysines (Lys252) and is held in place by an ordered active-site loop. In contrast, these features of the active-site structure are disordered or absent in the B subunit of the native human enzyme. The octameric structure of the zinc-dependent ALAD from the hyperthermophile Pyrobaculum calidifontis is also reported at a somewhat lower resolution of 3.5 Å. Finally, the details are presented of a high-resolution structure of the Escherichia coli ALAD enzyme co-crystallized with a noncovalently bound moiety of the product, porphobilinogen (PBG

Lead and PCB's in canvasback ducks: Relationship between enzyme levels and residues in blood

Science.gov (United States)

Dieter, M.P.; Perry, M.C.; Mulhern, B.M.

1976-01-01

Blood samples were taken for two successive years from canvasback ducks trapped in the Chesapeake Bay. The first winter (1972?1973) five plasma enzymes known to respond to organochlorine poisoning were examined. Abnormal enzyme elevations suggested that 20% of the population sampled (23/115 ducks) might contain organochlorine contaminants, but no residue analyses were performed. The second winter (1974) two of the same enzymes, aspartate aminotransferase and lactate dehydrogenase, and a third enzyme known to be specifically inhibited by lead, delta-aminolevulinic acid dehydratase, were assayed in 95 blood samples. Blood residues of organochlorine compounds and of lead were determined in representative samples, and the correlations between residue levels and enzyme changes were examined. The enzyme bioassays in 1974 indicated that lead was a more prevalent environmental contaminant than organochlorine compounds in canvasback ducks; 17% of the blood samples had less than one-half of the normal delta-aminolevulinic acid dehydratase activity, but only 11% exhibited abnormal aspartate aminotransferase or lactate dehydrogenase activities. These findings were confirmed by residue analyses that demonstrated lead concentrations four times higher than background levels, but only relatively low organochlorine concentrations. There was a highly significant inverse correlation between delta-aminolevulinic acid dehydratase activity and blood lead concentrations (Pcontamination in waterfowl. In canvasback ducks 200 ppb of lead in the blood caused a 75% decrease in delta-aminolevulinic acid dehydratase activity, a magnitude of enzyme inhibition that disturbs heme synthesis and is regarded as detrimental in humans.

Source and impact of lead contamination on {delta}-aminolevulinic acid dehydratase activity in several marine bivalve species along the Gulf of Cadiz

Energy Technology Data Exchange (ETDEWEB)

Company, R.; Serafim, A.; Lopes, B.; Cravo, A. [CIMA, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Kalman, J.; Riba, I.; DelValls, T.A. [Catedra UNESCO/UNITWIN/WiCop, Department of Physical-Chemistry, Faculty Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Cadiz (Spain); Blasco, J. [Instituto Ciencias Marinas Andalucia (CSIC), Campus Rio San Pedro, 11510 Puerto Real, Cadiz (Spain); Delgado, J. [Department of Geology, University of Huelva, Avda Fuerzas Armadas s/n, 21071 Huelva (Spain); Sarmiento, A.M. [Catedra UNESCO/UNITWIN/WiCop, Department of Physical-Chemistry, Faculty Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Cadiz (Spain); Department of Geology, University of Huelva, Avda Fuerzas Armadas s/n, 21071 Huelva (Spain); Nieto, J.M. [Department of Geology, University of Huelva, Avda Fuerzas Armadas s/n, 21071 Huelva (Spain); Shepherd, T.J.; Nowell, G. [Department of Earth Sciences, University of Durham, Science Laboratories, Durham DH1 3LE (United Kingdom); Bebianno, M.J., E-mail: mbebian@ualg.pt [CIMA, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)

2011-01-17

Coastal areas and estuaries are particularly sensitive to metal contamination from anthropogenic sources and in the last few decades the study of space-time distribution and variation of metals has been extensively researched. The Gulf of Cadiz is no exception, with several rivers draining one of the largest concentrations of sulphide deposits in the world, the Iberian Pyrite Belt (IPB). Of these rivers, the Guadiana, one of the most important in the Iberian Peninsula, together with smaller rivers like the Tinto and Odiel, delivers a very high metal load to the adjacent coastal areas. The purpose of this work was to study the source and impact of lead (Pb) drained from historical or active mining areas in the IPB on the activity of a Pb inhibited enzyme ({delta}-aminolevulinic acid dehydratase, ALAD) in several bivalve species along the Gulf of Cadiz. Seven marine species (Chamelea gallina, Mactra corallina, Donax trunculus, Cerastoderma edule, Mytilus galloprovincialis, Scrobicularia plana and Crassostrea angulata) were collected at 12 sites from Mazagon, near the mouth of the rivers Tinto and Odiel (Spain), to Cacela Velha (Ria Formosa lagoon system, Portugal). Lead concentrations, ALAD activity and lead isotope ratios ({sup 206}Pb/{sup 204}Pb, {sup 207}Pb/{sup 204}Pb and {sup 208}Pb/{sup 204}Pb) were determined in the whole soft tissues. The highest Pb concentrations were determined in S. plana (3.50 {+-} 1.09 {mu}g g{sup -1} Pb d.w.) and D. trunculus (1.95 {+-} 0.10 {mu}g g{sup -1} Pb d.w.), while M. galloprovincialis and C. angulata showed the lowest Pb levels (<0.38 {mu}g g{sup -1} Pb d.w.). In general, ALAD activity is negatively correlated with total Pb concentration. However this relationship is species dependent (e.g. linear for C. gallina ALAD = -0.36[Pb] + 0.79; r = 0.837; or exponential for M. galloprovincialis ALAD = 2.48e{sup -8.3[Pb]}; r = 0.911). This indicates that ALAD activity has considerable potential as a biomarker of Pb and moreover, in

Source and impact of lead contamination on δ-aminolevulinic acid dehydratase activity in several marine bivalve species along the Gulf of Cadiz

International Nuclear Information System (INIS)

Company, R.; Serafim, A.; Lopes, B.; Cravo, A.; Kalman, J.; Riba, I.; DelValls, T.A.; Blasco, J.; Delgado, J.; Sarmiento, A.M.; Nieto, J.M.; Shepherd, T.J.; Nowell, G.; Bebianno, M.J.

2011-01-01

Coastal areas and estuaries are particularly sensitive to metal contamination from anthropogenic sources and in the last few decades the study of space-time distribution and variation of metals has been extensively researched. The Gulf of Cadiz is no exception, with several rivers draining one of the largest concentrations of sulphide deposits in the world, the Iberian Pyrite Belt (IPB). Of these rivers, the Guadiana, one of the most important in the Iberian Peninsula, together with smaller rivers like the Tinto and Odiel, delivers a very high metal load to the adjacent coastal areas. The purpose of this work was to study the source and impact of lead (Pb) drained from historical or active mining areas in the IPB on the activity of a Pb inhibited enzyme (δ-aminolevulinic acid dehydratase, ALAD) in several bivalve species along the Gulf of Cadiz. Seven marine species (Chamelea gallina, Mactra corallina, Donax trunculus, Cerastoderma edule, Mytilus galloprovincialis, Scrobicularia plana and Crassostrea angulata) were collected at 12 sites from Mazagon, near the mouth of the rivers Tinto and Odiel (Spain), to Cacela Velha (Ria Formosa lagoon system, Portugal). Lead concentrations, ALAD activity and lead isotope ratios ( 206 Pb/ 204 Pb, 207 Pb/ 204 Pb and 208 Pb/ 204 Pb) were determined in the whole soft tissues. The highest Pb concentrations were determined in S. plana (3.50 ± 1.09 μg g -1 Pb d.w.) and D. trunculus (1.95 ± 0.10 μg g -1 Pb d.w.), while M. galloprovincialis and C. angulata showed the lowest Pb levels ( -1 Pb d.w.). In general, ALAD activity is negatively correlated with total Pb concentration. However this relationship is species dependent (e.g. linear for C. gallina ALAD = -0.36[Pb] + 0.79; r = 0.837; or exponential for M. galloprovincialis ALAD = 2.48e -8.3[Pb] ; r = 0.911). This indicates that ALAD activity has considerable potential as a biomarker of Pb and moreover, in marine bivalve species with different feeding habits. Lead isotope data

The effect of cell immobilization on the antibacterial activity of Lactobacillus reuteri DPC16 cells during passage through a simulated gastrointestinal tract system.

Science.gov (United States)

Zhao, Qian; Maddox, Ian S; Mutukumira, Anthony; Lee, Sung Je; Shu, Quan

2012-10-01

Cell immobilization has the ability to influence the survival and functional characteristics of probiotic bacterial strains in harsh environments. This study investigated the effect of cell immobilization and passage through a simulated gastrointestinal tract (GI) on the antibacterial activity of Lactobacillus reuteri DPC16. Antibacterial activity, reuterin production and diol dehydratase activity were assayed in recovered isolates of L. reuteri that had been immobilized in Ca alginate-skim milk, and incubated in simulated GI fluids. Among all the recovered isolates tested, any that had undergone immobilization followed by immediate recovery of the cells without subsequent incubation in any fluids demonstrated the highest reuterin production, antimicrobial activity and diol dehydratase enzyme activity. L. reuteri DPC16 cells that had been immobilized, incubated in simulated GI fluids, and subsequently recovered from the beads often showed some loss of antimicrobial activity compared to the immobilized cells. The data confirm that the process of immobilization of L. reuteri in Ca alginate-skim milk, rather than the passage through simulated GI fluids, resulted in enhanced antibacterial activity. This is attributed to increased diol dehydratase activity, resulting in increased reuterin production.

Protein (Cyanobacteria): 652996689 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available WP_027249156.1 ... 1117:7027 ... 1150:51287 1301283:72374 ... 54304:1227 1160:523 ... carbonate dehydratase Plankt...othrix agardhii MNKTQQNLTISRRNLLKFGAGVAGTAVLTVGLGTKVSLFKAQPAVAQNNITPEEALKQLLEGNQRFIE

Protein (Cyanobacteria): 652390540 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available WP_026786388.1 ... 1117:7027 ... 1150:51287 1301283:72374 ... 54304:1227 59512:475 ... carbonate dehydratase Plankt...othrix rubescens MNKTQQNLTISRRNLLKFGAGVAGTAVLTVGLGTKVSLFKAQPAVAQNGITPDEALNQLLEGNKRF

ENVISION: A Study to Evaluate the Efficacy and Safety of Givosiran (ALN-AS1) in Patients With Acute Hepatic Porphyrias (AHP)

Science.gov (United States)

2018-05-21

Acute Hepatic Porphyria; Acute Intermittent Porphyria; Porphyria, Acute Intermittent; Acute Porphyria; Hereditary Coproporphyria (HCP); Variegate Porphyria (VP); ALA Dehydratase Deficient Porphyria (ADP)

Protein (Cyanobacteria): 387469 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available YP_007107568.1 1117:24454 1150:5233 63132:9 1173025:9 3-dehydroquinate dehydratase Geit...lerinema sp. PCC 7407 MLSVLVLHGPNLNLLGLREPEVYGRSTLDDVNRLLEEEARSLQAEITALQSNHEGVLIDAIQAARGKHHGLLINPGAYTHTSVAIRDAIAGVAIPTVEVHLSNIHRREAFRHHSYIAPVAIGQISGFGVESYRLGLRALVAHLQSLDPA ...

Do circulating long non-coding RNAs (lncRNAs) (LincRNA-p21, GAS 5, HOTAIR) predict the treatment response in patients with head and neck cancer treated with chemoradiotherapy?

Science.gov (United States)

Fayda, Merdan; Isin, Mustafa; Tambas, Makbule; Guveli, Murat; Meral, Rasim; Altun, Musa; Sahin, Dilek; Ozkan, Gozde; Sanli, Yasemin; Isin, Husniye; Ozgur, Emre; Gezer, Ugur

2016-03-01

Long non-coding RNAs (lncRNAs) have been shown to be aberrantly expressed in head and neck cancer (HNC). The aim of the present study was to evaluate plasma levels of three lncRNA molecules (lincRNA-p21, GAS5, and HOTAIR) in the treatment response in HNC patients treated with radical chemoradiotherapy (CRT). Forty-one patients with HNC were enrolled in the study. Most of the patients had nasopharyngeal carcinoma (n = 27, 65.9 %) and locally advanced disease. Blood was drawn at baseline and treatment evaluation 4.5 months after therapy. lncRNAs in plasma were measured by semiquantitative PCR. Treatment response was evaluated according to clinical examination, RECIST and PERCIST criteria based on magnetic resonance imaging (MRI), and positron emission tomography with computed tomography (PET/CT) findings. Complete response (CR) rates were 73.2, 36.6, and 50 % for clinical investigation, PET/CT-, or MRI-based response evaluation, respectively. Predictive value of lncRNAs was investigated in patients with CR vs. those with partial response (PR)/progressive disease (PD). We found that post-treatment GAS5 levels in patients with PR/PD were significantly higher compared with patients with CR based on clinical investigation (p = 0.01). Receiver operator characteristic (ROC) analysis showed that at a cutoff value of 0.3 of GAS5, sensitivity and specificity for clinical tumor response were 82 and 77 %, respectively. Interestingly, pretreatment GAS5 levels were significantly increased in patients with PR/PD compared to those with CR upon MRI-based response evaluation (p = 0.042). In contrast to GAS5, pretreatment or post-treatment lincRNA-p21 and HOTAIR levels were not informative for treatment response. Our results suggest that circulating GAS5 could be a biomarker in predicting treatment response in HNC patients.

ORF Alignment: NC_002937 [GENIUS II[Archive

Lifescience Database Archive (English)

Full Text Available imerase/dehydratase family protein [Desulfovibrio ... vulgaris subsp. vulgaris str. Hildenborough] ... ...s subsp. vulgaris ... str. Hildenborough] ... Length = 282 ... Query: ...1 ... MKITLFGGAGFLGSHVCDKLSEAGHDVTVVDLRPSPYLRPDQTMITGNILDEELVARAVE 60 ... MKITLFGGAGFLGSHVCDKLSEAGHDVTVVDLRPSPYLRPDQTMITGNILDE...ELVARAVE Sbjct: 1 ... MKITLFGGAGFLGSHVCDKLSEAGHDVTVVDLRPSPYLRPDQTMITGNILDEELVARAVE 60 ...

An operational experience with cooling tower water system in chilling plant

International Nuclear Information System (INIS)

Rajan, Manju B.; Roy, Ankan; Ravi, K.V.

2015-01-01

Cooling towers are popular in industries as a very effective evaporative cooling technology for air conditioning. Supply of chilled water to air conditioning equipments of various plant buildings and cooling tower water to important equipments for heat removal is the purpose of chilling plant at PRPD. The cooling medium used is raw water available at site. Water chemistry is maintained by make-up and blowdown. In this paper, various observations made during plant operation and equipment maintenance are discussed. The issues observed was scaling and algal growth affecting the heat transfer and availability of the equipment. Corrosion related issues were observed to be less significant. Scaling indices were calculated to predict the behavior. (author)

Sequence Classification: 543110 [

Lifescience Database Archive (English)

Full Text Available Non-TMB Non-TMH Non-TMB Non-TMB Non-TMB Non-TMB >gi|16767113|ref|NP_462728.1| 2-oxo-3-deoxygalactona...te 6-phosphate aldolase/galactonate dehydratase || http://www.ncbi.nlm.nih.gov/protein/16767113 ...

Sequence Classification: 378184 [

Lifescience Database Archive (English)

Full Text Available Non-TMB Non-TMH Non-TMB Non-TMB Non-TMB Non-TMB >gi|13475903|ref|NP_107473.1| 2-oxo-3-deoxygalactona...te 6-phosphate aldolase and galactonate dehydratase || http://www.ncbi.nlm.nih.gov/protein/13475903 ...

SwissProt search result: AK060777 [KOME

Lifescience Database Archive (English)

Full Text Available AK060777 001-033-C01 (P17067) Carbonic anhydrase, chloroplast precursor (EC 4.2.1.1) (Carbon...ate dehydratase) [Contains: Carbonic anhydrase, 27 kDa isoform; Carbonic anhydrase, 25 kDa isoform] CAHC_PEA 2e-44 ...

Sequence Classification: 378420 [

Lifescience Database Archive (English)

Full Text Available onate 6-phosphate aldolase and galactonate dehydratase || http://www.ncbi.nlm.nih.gov/protein/13476139 ... ...Non-TMB Non-TMH Non-TMB Non-TMB Non-TMB Non-TMB >gi|13476139|ref|NP_107709.1| similar to 2-oxo-3-deoxygalact

NCBI nr-aa BLAST: CBRC-CFAM-16-0042 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-CFAM-16-0042 gb|AAC46251.1| putative epimerase/dehydratase [Vibrio cholerae O1...39] dbj|BAA33614.1| unknown [Vibrio cholerae] gb|EAZ47467.1| UDP-D-quinovosamine 4-dehydrogenase [Vibrio cholerae MO10] AAC46251.1 0.46 27% ...

Porphyrins profile by high performance liquid chromatography ...

African Journals Online (AJOL)

E. Fateen

2008-09-07

Sep 7, 2008 ... acid dehydratase porphyria (ADP), acute intermittent por- phyria (AIP) ..... affecting motor neurons, and can lead to respiratory and bul- bar paralysis and ... variable degrees of fatty damage and chronic inflammatory changes [1]. ..... ppix influences the hematologic status and iron metabolism in patients with ...

Structure of Arabidopsis Dehydroquinate Dhydratase-Shikimate Dehydrogeanse and Implications for Metabolic Channeling in the Shikimate Pathway

International Nuclear Information System (INIS)

Singh, S.; Christendat, D.

2006-01-01

The bifunctional enzyme dehydroquinate dehydratase-shikimate dehydrogenase (DHQ-SDH) catalyzes the dehydration of dehydroquinate to dehydroshikimate and the reduction of dehydroshikimate to shikimate in the shikimate pathway. We report the first crystal structure of Arabidopsis DHQ-SDH with shikimate bound at the SDH site and tartrate at the DHQ site. The interactions observed in the DHQ-tartrate complex reveal a conserved mode for substrate binding between the plant and microbial DHQ dehydratase family of enzymes. The SDH-shikimate complex provides the first direct evidence of the role of active site residues in the catalytic mechanism. Site-directed mutagenesis and mechanistic analysis revealed that Asp 423 and Lys 385 are key catalytic groups and Ser 336 is a key binding group. The arrangement of the two functional domains reveals that the control of metabolic flux through the shikimate pathway is achieved by increasing the effective concentration of dehydroshikimate through the proximity of the two sites

Biosynthetic pathways to delta-aminolevulinic acid induced by blue light in the pigment mutant C-2A' of Scenedesmus obliquus

International Nuclear Information System (INIS)

Klein, O.; Senger, H.

1978-01-01

The X-ray induced mutant C-2A' of Scenedesmus obliquus grows heterotrophically but forms only traces of chlorophyll in the dark. Upon illumination, delta-aminolevulinic acid (ALA) is synthesized and chlorophyll is formed. These processes are blue light dependent and ceased immediately when the cells were transferred back into darkness. Addition of levulinic acid (LA) inhibited the light-dependent formation of chlorophyll and caused accumulation of ALA by competitive inhibition of the ALA dehydratase (EC. 4.2.1.24). By feeding specifically labelled 14 C precursors to the pigment mutant, inhibiting the ALA dehydratase with LA, accumulating, extracting and analyzing the ALA, two pathways leading towards ALA could be established: glycine and succinyl CoA can be condensed to ALA and the 5 carbon skeleton of glutamate can completely be incorporated into ALA via a second pathway. The glycine-succinyl CoA pathway dominated over the glutamate pathway, but both led to chlorophyll formation. (author)

Effect of lead on heme synthesis

Energy Technology Data Exchange (ETDEWEB)

Neuberger, A.

1975-01-01

Recently, a fair amount of work has been done on the effect of lead on porphobilinogen dehydratase, which has been used as a sensitive indicator of lead poisoning. How far this is in itself harmful depends on the Michaelis constants of both the aminolaevulinic synthetase and of the dehydratase, and in addition on the relative activities of the two enzymes in a cell and also on the tissue concentration of glycine. Information on some of these points is still fragmentary, and a reliable judgement is at the present not very easy. Another step in the heme synthesis, which is sensitive to low concentrations of lead, is the incorporation of iron into protoporphyrin. Inhibition of this step may be important in accounting to a large extent for the anaemia found in individuals with lead poisoning. Reduction in the tissue concentration of heme or of heme-like compounds may also explain, through the mechanism of de-repression, the excretion of increased amounts of aminolaevulinic acid in the urine observed in cases of lead poisoning. A third step in heme synthesis, which might be sensitive to lead, is the oxidative decarboxylation of coproporphyrin to protoporphyrin, and this may explain why the former derivative is excreted in the urine. Recent work of the Harvard Medical School has indicated that greatly reduced levels of ALA dehydratase may be found in most cases of severe liver damage due to alcoholism. In most of these cases the level of lead in the blood is within normal limits, and there is no history of exposure to toxic amounts of lead. We therefore have to assume that a reduction in the blood level of this enzyme is not necessarily an indication of lead poisoning.

The effect of haem biosynthesis inhibitors and inducers on intestinal iron absorption and liver haem biosynthetic enzyme activities

International Nuclear Information System (INIS)

Laftah, A.H.; Simpson, R.J.; Peters, T.J.; Raja, K.B.

2008-01-01

The relation between haem biosynthesis and intestinal iron absorption is not well understood, we therefore investigated the effect of compounds that alter haem metabolism on duodenal iron absorption. CD1 mice were treated with either an inhibitor (succinyl acetone (SA)) or stimulator (2-allyl-2-isopropylacetamide (AIA)) of haem biosynthesis. 5-Aminolaevulinic acid (ALA) dehydratase and urinary ALA and porphobilinogen (PBG) levels, were determined. Intestinal iron absorption was assayed with in vivo and in vitro techniques. Liver hepcidin (Hamp1) and duodenal iron transporter mRNA levels were measured using RT-PCR. AIA caused increased hepatic ALA synthase (1.6-fold) and ALA dehydratase (1.4-fold, both p < 0.005) activities and increased urinary ALA and PBG excretion (2.1- and 1.4-fold, p < 0.005, p < 0.05, respectively). In vivo intestinal iron absorption was reduced to 49% of control (p < 0.005). Mice treated with SA showed decreased urinary ALA and PBG levels (75 and 55% control, both p < 0.005) and reductions in both ALA synthase and ALA dehydratase activities (77 and 56% control, p < 0.05, p < 0.005, respectively) in the liver. Liver and duodenal haem and cytochrome oxidase levels were not significantly decreased. Iron absorption was enhanced (1.26-fold, p < 0.05) and hepatic Hamp1 mRNA was reduced (53% of control, p < 0.05). In vitro duodenal iron uptake after mice were injected with SA also demonstrated an increase in Fe(III) reduction and uptake (1.27- and 1.41-fold, p < 0.01 respectively). Simultaneous injections of SA and ALA blocked the enhancing effect on iron absorption seen with SA alone. We conclude that alterations in haem biosynthesis can influence iron absorption and in particular, the intermediate ALA seems to be an inhibitor of iron absorption

Two novel classes of enzymes are required for the biosynthesis of aurofusarin in Fusarium graminearum

DEFF Research Database (Denmark)

Frandsen, Rasmus John Normand; Schütt, Claes; Lund, Birgitte W.

2011-01-01

genes, aurZ and aurS. Targeted gene replacement of aurZ resulted in the discovery that the compound YWA1, rather than nor-rubrofusarin, is the primary product of F. graminearum polyketide synthase 12 (FgPKS12). AurZ is the first representative of a novel class of dehydratases that act on hydroxylated γ...

Disease-associated prion protein in neural and lymphoid tissues of mink (Mustela vison) inoculated with transmissible mink encephalopathy.

Science.gov (United States)

Schneider, D A; Harrington, R D; Zhuang, D; Yan, H; Truscott, T C; Dassanayake, R P; O'Rourke, K I

2012-11-01

Transmissible spongiform encephalopathies (TSEs) are diagnosed by immunodetection of disease-associated prion protein (PrP(d)). The distribution of PrP(d) within the body varies with the time-course of infection and between species, during interspecies transmission, as well as with prion strain. Mink are susceptible to a form of TSE known as transmissible mink encephalopathy (TME), presumed to arise due to consumption of feed contaminated with a single prion strain of ruminant origin. After extended passage of TME isolates in hamsters, two strains emerge, HY and DY, each of which is associated with unique structural isoforms of PrP(TME) and of which only the HY strain is associated with accumulation of PrP(TME) in lymphoid tissues. Information on the structural nature and lymphoid accumulation of PrP(TME) in mink is limited. In this study, 13 mink were challenged by intracerebral inoculation using late passage TME inoculum, after which brain and lymphoid tissues were collected at preclinical and clinical time points. The distribution and molecular nature of PrP(TME) was investigated by techniques including blotting of paraffin wax-embedded tissue and epitope mapping by western blotting. PrP(TME) was detected readily in the brain and retropharyngeal lymph node during preclinical infection, with delayed progression of accumulation within other lymphoid tissues. For comparison, three mink were inoculated by the oral route and examined during clinical disease. Accumulation of PrP(TME) in these mink was greater and more widespread, including follicles of rectoanal mucosa-associated lymphoid tissue. Western blot analyses revealed that PrP(TME) accumulating in the brain of mink is structurally most similar to that accumulating in the brain of hamsters infected with the DY strain. Collectively, the results of extended passage in mink are consistent with the presence of only a single strain of TME, the DY strain, capable of inducing accumulation of PrP(TME) in the lymphoid

A Comparison of Inductive Sensors in the Characterization of Partial Discharges and Electrical Noise Using the Chromatic Technique.

Science.gov (United States)

Ardila-Rey, Jorge Alfredo; Montaña, Johny; de Castro, Bruno Albuquerque; Schurch, Roger; Covolan Ulson, José Alfredo; Muhammad-Sukki, Firdaus; Bani, Nurul Aini

2018-03-29

Partial discharges (PDs) are one of the most important classes of ageing processes that occur within electrical insulation. PD detection is a standardized technique to qualify the state of the insulation in electric assets such as machines and power cables. Generally, the classical phase-resolved partial discharge (PRPD) patterns are used to perform the identification of the type of PD source when they are related to a specific degradation process and when the electrical noise level is low compared to the magnitudes of the PD signals. However, in practical applications such as measurements carried out in the field or in industrial environments, several PD sources and large noise signals are usually present simultaneously. In this study, three different inductive sensors have been used to evaluate and compare their performance in the detection and separation of multiple PD sources by applying the chromatic technique to each of the measured signals.

A Comparison of Inductive Sensors in the Characterization of Partial Discharges and Electrical Noise Using the Chromatic Technique

Directory of Open Access Journals (Sweden)

Jorge Alfredo Ardila-Rey

2018-03-01

Full Text Available Partial discharges (PDs are one of the most important classes of ageing processes that occur within electrical insulation. PD detection is a standardized technique to qualify the state of the insulation in electric assets such as machines and power cables. Generally, the classical phase-resolved partial discharge (PRPD patterns are used to perform the identification of the type of PD source when they are related to a specific degradation process and when the electrical noise level is low compared to the magnitudes of the PD signals. However, in practical applications such as measurements carried out in the field or in industrial environments, several PD sources and large noise signals are usually present simultaneously. In this study, three different inductive sensors have been used to evaluate and compare their performance in the detection and separation of multiple PD sources by applying the chromatic technique to each of the measured signals.

Towards Optical Partial Discharge Detection with Micro Silicon Photomultipliers

Directory of Open Access Journals (Sweden)

Ming Ren

2017-11-01

Full Text Available Optical detection is reliable in intrinsically characterizing partial discharges (PDs. Because of the great volume and high-level power supply of the optical devices that can satisfy the requirements in photosensitivity, optical PD detection can merely be used in laboratory studies. To promote the practical application of the optical approach in an actual power apparatus, a silicon photomultiplier (SiPM-based PD sensor is introduced in this paper, and its basic properties, which include the sensitivity, pulse resolution, correlation with PD severity, and electromagnetic (EM interference immunity, are experimentally evaluated. The stochastic phase-resolved PD pattern (PRPD for three typical insulation defects are obtained by SiPM PD detector and are compared with those obtained using a high-frequency current transformer (HFCT and a vacuum photomultiplier tube (PMT. Because of its good performances in the above aspects and its additional advantages, such as the small size, low power supply, and low cost, SiPM offers great potential in practical optical PD monitoring.

Giant virus Megavirus chilensis encodes the biosynthetic pathway for uncommon acetamido sugars.

Science.gov (United States)

Piacente, Francesco; De Castro, Cristina; Jeudy, Sandra; Molinaro, Antonio; Salis, Annalisa; Damonte, Gianluca; Bernardi, Cinzia; Abergel, Chantal; Tonetti, Michela G

2014-08-29

Giant viruses mimicking microbes, by the sizes of their particles and the heavily glycosylated fibrils surrounding their capsids, infect Acanthamoeba sp., which are ubiquitous unicellular eukaryotes. The glycans on fibrils are produced by virally encoded enzymes, organized in gene clusters. Like Mimivirus, Megavirus glycans are mainly composed of virally synthesized N-acetylglucosamine (GlcNAc). They also contain N-acetylrhamnosamine (RhaNAc), a rare sugar; the enzymes involved in its synthesis are encoded by a gene cluster specific to Megavirus close relatives. We combined activity assays on two enzymes of the pathway with mass spectrometry and NMR studies to characterize their specificities. Mg534 is a 4,6-dehydratase 5-epimerase; its three-dimensional structure suggests that it belongs to a third subfamily of inverting dehydratases. Mg535, next in the pathway, is a bifunctional 3-epimerase 4-reductase. The sequential activity of the two enzymes leads to the formation of UDP-l-RhaNAc. This study is another example of giant viruses performing their glycan synthesis using enzymes different from their cellular counterparts, raising again the question of the origin of these pathways. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Effect of Lineage-Specific Metabolic Traits of Lactobacillus reuteri on Sourdough Microbial Ecology

OpenAIRE

Lin, Xiaoxi B.; Gänzle, Michael G.

2014-01-01

This study determined the effects of specific metabolic traits of Lactobacillus reuteri on its competitiveness in sourdoughs. The competitiveness of lactobacilli in sourdough generally depends on their growth rate; acid resistance additionally contributes to competitiveness in sourdoughs with long fermentation times. Glycerol metabolism via glycerol dehydratase (gupCDE) accelerates growth by the regeneration of reduced cofactors; glutamate metabolism via glutamate decarboxylase (gadB) increas...

Laboratory results of some biological measures in workers exposed to lead

Energy Technology Data Exchange (ETDEWEB)

Secchi, G.C.; Alessio, L.

1974-12-01

Erthrocyte ALA-dehydratase (ALAD) activity and blood lead values were studied in different groups of subjects not occupationally exposed to lead and compared with values for exposed workers. The results lead to the conclusion that measurement of ALAD activity is more useful in evaluating possible exposure of general population groups to minimal quantities of lead than in the surveillance of workers in the lead industries.

Identification of the missing links in prokaryotic pentose oxidation pathways: evidence for enzyme recruitment.

Science.gov (United States)

Brouns, Stan J J; Walther, Jasper; Snijders, Ambrosius P L; van de Werken, Harmen J G; Willemen, Hanneke L D M; Worm, Petra; de Vos, Marjon G J; Andersson, Anders; Lundgren, Magnus; Mazon, Hortense F M; van den Heuvel, Robert H H; Nilsson, Peter; Salmon, Laurent; de Vos, Willem M; Wright, Phillip C; Bernander, Rolf; van der Oost, John

2006-09-15

The pentose metabolism of Archaea is largely unknown. Here, we have employed an integrated genomics approach including DNA microarray and proteomics analyses to elucidate the catabolic pathway for D-arabinose in Sulfolobus solfataricus. During growth on this sugar, a small set of genes appeared to be differentially expressed compared with growth on D-glucose. These genes were heterologously overexpressed in Escherichia coli, and the recombinant proteins were purified and biochemically studied. This showed that D-arabinose is oxidized to 2-oxoglutarate by the consecutive action of a number of previously uncharacterized enzymes, including a D-arabinose dehydrogenase, a D-arabinonate dehydratase, a novel 2-keto-3-deoxy-D-arabinonate dehydratase, and a 2,5-dioxopentanoate dehydrogenase. Promoter analysis of these genes revealed a palindromic sequence upstream of the TATA box, which is likely to be involved in their concerted transcriptional control. Integration of the obtained biochemical data with genomic context analysis strongly suggests the occurrence of pentose oxidation pathways in both Archaea and Bacteria, and predicts the involvement of additional enzyme components. Moreover, it revealed striking genetic similarities between the catabolic pathways for pentoses, hexaric acids, and hydroxyproline degradation, which support the theory of metabolic pathway genesis by enzyme recruitment.

Mutation of a Rice Gene Encoding a Phenylalanine Biosynthetic Enzyme Results in Accumulation of Phenylalanine and Tryptophan[W

Science.gov (United States)

Yamada, Tetsuya; Matsuda, Fumio; Kasai, Koji; Fukuoka, Shuichi; Kitamura, Keisuke; Tozawa, Yuzuru; Miyagawa, Hisashi; Wakasa, Kyo

2008-01-01

Two distinct biosynthetic pathways for Phe in plants have been proposed: conversion of prephenate to Phe via phenylpyruvate or arogenate. The reactions catalyzed by prephenate dehydratase (PDT) and arogenate dehydratase (ADT) contribute to these respective pathways. The Mtr1 mutant of rice (Oryza sativa) manifests accumulation of Phe, Trp, and several phenylpropanoids, suggesting a link between the synthesis of Phe and Trp. Here, we show that the Mtr1 mutant gene (mtr1-D) encodes a form of rice PDT with a point mutation in the putative allosteric regulatory region of the protein. Transformed callus lines expressing mtr1-D exhibited all the characteristics of Mtr1 callus tissue. Biochemical analysis revealed that rice PDT possesses both PDT and ADT activities, with a preference for arogenate as substrate, suggesting that it functions primarily as an ADT. The wild-type enzyme is feedback regulated by Phe, whereas the mutant enzyme showed a reduced feedback sensitivity, resulting in Phe accumulation. In addition, these observations indicate that rice PDT is critical for regulating the size of the Phe pool in plant cells. Feeding external Phe to wild-type callus tissue and seedlings resulted in Trp accumulation, demonstrating a connection between Phe accumulation and Trp pool size. PMID:18487352

Vision Issues and Space Flight: Evaluation of One-Carbon Metabolism Polymorphisms

Science.gov (United States)

Smith, Scott M.; Gregory, Jesse F.; Zeisel, Steven; Ueland, Per; Gibson, C. R.; Mader, Thomas; Kinchen, Jason; Ploutz-Snyder, Robert; Zwart, Sara R.

2015-01-01

Intermediates of the one-carbon metabolic pathway are altered in astronauts who experience vision-related issues during and after space flight. Serum concentrations of homocysteine, cystathionine, 2-methylcitric acid, and methylmalonic acid were higher in astronauts with ophthalmic changes than in those without (Zwart et al., J Nutr, 2012). These differences existed before, during, and after flight. Potential confounding factors did not explain the differences. Genetic polymorphisms could contribute to these differences, and could help explain why crewmembers on the same mission do not all have ophthalmic issues, despite the same environmental factors (e.g., microgravity, exercise, diet). A follow-up study was conducted to evaluate 5 polymorphisms of enzymes in the one-carbon pathway, and to evaluate how these relate to vision and other ophthalmic changes after flight. Preliminary evaluations of the genetic data indicate that all of the crewmembers with the MTRR GG genotype had vision issues to one degree or another. However, not everyone who had vision issues had this genetic polymorphism, so the situation is more complex than the involvement of this single polymorphism. Metabolomic and further data analyses are underway to clarify these findings, but the preliminary assessments are promising.

Congenital myopathy is caused by mutation of HACD1

OpenAIRE

Muhammad, Emad; Reish, Orit; Ohno, Yusuke; Scheetz, Todd; DeLuca, Adam; Searby, Charles; Regev, Miriam; Benyamini, Lilach; Fellig, Yakov; Kihara, Akio; Sheffield, Val C.; Parvari, Ruti

2013-01-01

Congenital myopathies are heterogeneous inherited diseases of muscle characterized by a range of distinctive histologic abnormalities. We have studied a consanguineous family with congenital myopathy. Genome-wide linkage analysis and whole-exome sequencing identified a homozygous non-sense mutation in 3-hydroxyacyl-CoA dehydratase 1 (HACD1) in affected individuals. The mutation results in non-sense mediated decay of the HACD1 mRNA to 31% of control levels in patient muscle and completely abro...

Zonation of heme synthesis enzymes in mouse liver and their regulation by β-catenin and Ha-ras.

Science.gov (United States)

Braeuning, Albert; Schwarz, Michael

2010-11-01

Cytochrome P450 (CYP) hemoproteins play an important role in hepatic biotransformation. Recently, β-catenin and Ha-ras signaling have been identified as players controlling transcription of various CYP genes in mouse liver. The aim of the present study was to analyze the role of β-catenin and Ha-ras in the regulation of heme synthesis. Heme synthesis-related gene expression was analyzed in normal liver, in transgenic mice expressing activated β-catenin or Ha-ras, and in hepatomas. Regulation of the aminolevulinate dehydratase promoter was studied in vitro. Elevated expression of mRNAs and proteins involved in heme biosynthesis was linked to β-catenin activation in perivenous hepatocytes, in transgenic hepatocytes, and in hepatocellular tumors. Stimulation of the aminolevulinate dehydratase promoter by β-catenin was independent of the β-catenin/T-cell-specific transcription factor dimer. By contrast, activation of Ha-ras repressed heme synthesis-related gene expression. The present data suggest that β-catenin enhances the expression of both CYPs and heme synthesis-related genes, thus coordinating the availability of CYP apoprotein and its prosthetic group heme. The reciprocal regulation of heme synthesis by β-catenin and Ha-ras-dependent signaling supports our previous hypothesis that antagonistic action of these pathways plays a major role in the control of zonal gene expression in healthy mouse liver and aberrant expression patterns in hepatocellular tumors.

Lead induces DNA damage and alteration of ALAD and antioxidant genes mRNA expression in construction site workers.

Science.gov (United States)

Akram, Zertashia; Riaz, Sadaf; Kayani, Mahmood Akhtar; Jahan, Sarwat; Ahmad, Malik Waqar; Ullah, Muhammad Abaid; Wazir, Hizbullah; Mahjabeen, Ishrat

2018-01-16

Oxidative stress and DNA damage are considered as possible mechanisms involved in lead toxicity. To test this hypothesis, DNA damage and expression variations of aminolevulinic acid dehydratase (ALAD), superoxide dismutase 2 (SOD2), and 8-oxoguanine DNA glycosylase 2a (OGG1-2a) genes was studied in a cohort of 100 exposed workers and 100 controls with comet assay and real-time polymerse chain reaction (PCR). Results indicated that increased number of comets was observed in exposed workers versus controls (p gene.

Blood Pb and δ-ALAD inhibition in cattle and sheep from a Pb-polluted mining area

International Nuclear Information System (INIS)

Rodríguez-Estival, Jaime; Barasona, José A.; Mateo, Rafael

2012-01-01

The effects of Pb pollution on cattle and sheep raised in an ancient mining area were studied through the use of blood Pb (PbB) levels and δ-aminolevulinic acid dehydratase (δ-ALAD) activity. Lead levels in livestock blood from the mining area (n = 110) were significantly elevated when compared to the controls (n = 79). In 91.4% of cattle (n = 58) and 13.5% of sheep (n = 52) sampled in the mining area, PbB levels corresponded to subclinical exposure (6–35 μg/dl). Two young cattle ( 35 μg/dl). Elevated PbB was also accompanied by δ-ALAD activity inhibition in blood, which confirms that measurable effects of Pb poisoning were taking place. Observed PbB levels suggest that a potential risk to human consumers of beef from the Pb polluted areas may also exist, as has been shown previously for game meat from the same mining area. - Highlights: ► We studied effects of Pb pollution on livestock raised in an old mining area. ► Livestock from the mining area had higher blood Pb levels than the controls. ► Pb levels were higher in cattle than in sheep. ► Pb exposure inhibited δ-aminolevulinic acid dehydratase, especially in cattle. ► Lead uptake in livestock reared in this area poses a risk to human consumers. - Lead from an ancient mining area still affects livestock health and compromises the safety of derived food products.

The Mycobacterium tuberculosis Complex has a Pathway for the Biosynthesis of 4-Formamido-4,6-Dideoxy-d-Glucose.

Science.gov (United States)

Brown, Haley A; Vinogradov, Evgeny; Gilbert, Michel; Holden, Hazel M

2018-05-15

Recent studies have demonstrated that the O-antigens of some pathogenic bacteria such as Brucella abortus, Francisella tularensis, and Campylobacter jejuni contain quite unusual N-formylated sugars (3-formamido-3,6-dideoxy-d-glucose or 4-formamido-4,6-dideoxy-d-glucose). Typically, four enzymes are required for the formation of such sugars: a thymidylyltransferase, a 4,6-dehydratase, a pyridoxal 5'-phosphate or PLP-dependent aminotransferase, and an N-formyltransferase. To date, there have been no published reports of N-formylated sugars associated with Mycobacterium tuberculosis. A recent investigation from our laboratories, however, has demonstrated that one gene product from M. tuberculosis, Rv3404c, functions as a sugar N-formyltransferase. Given that M. tuberculosis produces l-rhamnose, both a thymidylyltransferase (Rv0334) and a 4,6-dehydratase (Rv3464) required for its formation have been identified. Thus, there is one remaining enzyme needed for the production of an N-formylated sugar in M. tuberculosis, namely a PLP-dependent aminotransferase. Here we demonstrate that the M. tuberculosis rv3402c gene encodes such an enzyme. Our data prove that M. tuberculosis contains all of the enzymatic activities required for the formation of dTDP-4-formamido-4,6-dideoxy-d-glucose. Indeed, the rv3402c gene product likely contributes to virulence or persistence during infection, though its temporal expression and location remain to be determined. This article is protected by copyright. All rights reserved. © 2018 The Protein Society.

Influence of high glycine diets on the activity of glycine-catabolizing enzymes and on glycine catabolism in rats

International Nuclear Information System (INIS)

Petzke, K.J.; Albrecht, V.; Przybilski, H.

1986-01-01

Male albino rats were adapted to isocaloric purified diets that differed mainly in their glycine and casein contents. Controls received a 30% casein diet. In experimental diets gelatin or gelatin hydrolysate was substituted for half of the 30% casein. An additional group was fed a glycine-supplemented diet, which corresponded in glycine level to the gelatin diet but in which the protein level was nearly the same as that of the casein control diet. Another group received a 15% casein diet. Rat liver glycine cleavage system, serine hydroxymethyltransferase and serine dehydratase activities were measured. 14 CO 2 production from the catabolism of 14 C-labeled glycine was measured in vivo and in vitro (from isolated hepatocytes). Serine dehydratase and glycine cleavage system activities were higher in animals fed 30% casein diets than in those fed 15% casein diets. Serine hydroxymethyltransferase activity of the cytosolic and mitochondrial fractions was highest when a high glycine diet (glycine administered as pure, protein bound in gelatin or peptide bound in gelatin hydrolysate) was fed. 14 CO 2 formation from [1- 14 C]- and [2- 14 C]glycine both in vivo and in isolated hepatocytes was higher when a high glycine diet was fed than when a casein diet was fed. These results suggest that glycine catabolism is dependent on and adaptable to the glycine content of the diet. Serine hydroxymethyltransferase appears to play a major role in the regulation of glycine degradation via serine and pyruvate

ThrR, a DNA-binding transcription factor involved in controlling threonine biosynthesis in Bacillus subtilis.

Science.gov (United States)

Rosenberg, Jonathan; Müller, Peter; Lentes, Sabine; Thiele, Martin J; Zeigler, Daniel R; Tödter, Dominik; Paulus, Henry; Brantl, Sabine; Stülke, Jörg; Commichau, Fabian M

2016-09-01

The threonine dehydratase IlvA is part of the isoleucine biosynthesis pathway in the Gram-positive model bacterium Bacillus subtilis. Consequently, deletion of ilvA causes isoleucine auxotrophy. It has been reported that ilvA pseudo-revertants having a derepressed hom-thrCB operon appear in the presence of threonine. Here we have characterized two classes of ilvA pseudo-revertants. In the first class the hom-thrCB operon was derepressed unmasking the threonine dehydratase activity of the threonine synthase ThrC. In the second class of mutants, threonine biosynthesis was more broadly affected. The first class of ilvA pseudo-revertants had a mutation in the Phom promoter (P*hom ), resulting in constitutive expression of the hom-thrCB operon. In the second class of ilvA pseudo-revertants, the thrR gene encoding a putative DNA-binding protein was inactivated, also resulting in constitutive expression of the hom-thrCB operon. Here we demonstrate that ThrR is indeed a DNA-binding transcription factor that regulates the hom-thrCB operon and the thrD aspartokinase gene. DNA binding assays uncovered the DNA-binding site of ThrR and revealed that the repressor competes with the RNA polymerase for DNA binding. This study also revealed that ThrR orthologs are ubiquitous in genomes from the Gram-positive phylum Firmicutes and in some Gram-negative bacteria. © 2016 John Wiley & Sons Ltd.

Characterisation of PduS, the pdu metabolosome corrin reductase, and evidence of substructural organisation within the bacterial microcompartment.

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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.

In vitro activity of wALADin benzimidazoles against different life cycle stages of Plasmodium parasites.

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Lentz, Christian S; Sattler, Julia M; Fendler, Martina; Gottwalt, Simon; Halls, Victoria S; Strassel, Silke; Arriens, Sandra; Hannam, Jeffrey S; Specht, Sabine; Famulok, Michael; Mueller, Ann-Kristin; Hoerauf, Achim; Pfarr, Kenneth M

2015-01-01

wALADin1 benzimidazoles are specific inhibitors of δ-aminolevulinic acid dehydratase from Wolbachia endobacteria of filarial nematodes. We report that wALADin1 and two derivatives killed blood stage Plasmodium falciparum in vitro (50% inhibitory concentrations, 39, 7.7, and 12.8 μM, respectively). One of these derivatives inhibited gliding motility of Plasmodium berghei ANKA infectious sporozoites with nanomolar affinity and blocked invasion into hepatocytes but did not affect intrahepatocytic replication. Hence, wALADin1 benzimidazoles are tools to study gliding motility and potential antiplasmodial drug candidates. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Possible case of maternal transmission of feline spongiform encephalopathy in a captive cheetah.

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Anna Bencsik

Full Text Available Feline spongiform encephalopathy (FSE is considered to be related to bovine spongiform encephalopathy (BSE and has been reported in domestic cats as well as in captive wild cats including cheetahs, first in the United Kingdom (UK and then in other European countries. In France, several cases were described in cheetahs either imported from UK or born in France. Here we report details of two other FSE cases in captive cheetah including a 2(nd case of FSE in a cheetah born in France, most likely due to maternal transmission. Complete prion protein immunohistochemical study on both brains and peripheral organs showed the close likeness between the two cases. In addition, transmission studies to the TgOvPrP4 mouse line were also performed, for comparison with the transmission of cattle BSE. The TgOvPrP4 mouse brains infected with cattle BSE and cheetah FSE revealed similar vacuolar lesion profiles, PrP(d brain mapping with occurrence of typical florid plaques. Collectively, these data indicate that they harbor the same strain of agent as the cattle BSE agent. This new observation may have some impact on our knowledge of vertical transmission of BSE agent-linked TSEs such as in housecat FSE, or vCJD.

Effect of lineage-specific metabolic traits of Lactobacillus reuteri on sourdough microbial ecology.

Science.gov (United States)

Lin, Xiaoxi B; Gänzle, Michael G

2014-09-01

This study determined the effects of specific metabolic traits of Lactobacillus reuteri on its competitiveness in sourdoughs. The competitiveness of lactobacilli in sourdough generally depends on their growth rate; acid resistance additionally contributes to competitiveness in sourdoughs with long fermentation times. Glycerol metabolism via glycerol dehydratase (gupCDE) accelerates growth by the regeneration of reduced cofactors; glutamate metabolism via glutamate decarboxylase (gadB) increases acid resistance by generating a proton motive force. Glycerol and glutamate metabolisms are lineage-specific traits in L. reuteri; therefore, this study employed glycerol dehydratase-positive sourdough isolates of human-adapted L. reuteri lineage I, glutamate decarboxylase-positive strains of rodent-adapted L. reuteri lineage II, as well as mutants with deletions in gadB or gupCDE. The competitivenesses of the strains were quantified by inoculation of wheat and sorghum sourdoughs with defined strains, followed by propagation of doughs with a 10% inoculum and 12-h or 72-h fermentation cycles. Lineage I L. reuteri strains dominated sourdoughs propagated with 12-h fermentation cycles; lineage II L. reuteri strains dominated sourdoughs propagated with 72-h fermentation cycles. L. reuteri 100-23ΔgadB was outcompeted by its wild-type strain in sourdoughs fermented with 72-h fermentation cycles; L. reuteri FUA3400ΔgupCDE was outcompeted by its wild-type strain in sourdoughs fermented with both 12-h and 72-h fermentation cycles. Competition experiments with isogenic pairs of strains resulted in a constant rate of strain displacement of the less competitive mutant strain. In conclusion, lineage-specific traits of L. reuteri determine the competitiveness of this species in sourdough fermentations. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Analysis of hypoxia and hypoxia-like states through metabolite profiling.

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Julie E Gleason

Full Text Available In diverse organisms, adaptation to low oxygen (hypoxia is mediated through complex gene expression changes that can, in part, be mimicked by exposure to metals such as cobalt. Although much is known about the transcriptional response to hypoxia and cobalt, little is known about the all-important cell metabolism effects that trigger these responses.Herein we use a low molecular weight metabolome profiling approach to identify classes of metabolites in yeast cells that are altered as a consequence of hypoxia or cobalt exposures. Key findings on metabolites were followed-up by measuring expression of relevant proteins and enzyme activities. We find that both hypoxia and cobalt result in a loss of essential sterols and unsaturated fatty acids, but the basis for these changes are disparate. While hypoxia can affect a variety of enzymatic steps requiring oxygen and heme, cobalt specifically interferes with diiron-oxo enzymatic steps for sterol synthesis and fatty acid desaturation. In addition to diiron-oxo enzymes, cobalt but not hypoxia results in loss of labile 4Fe-4S dehydratases in the mitochondria, but has no effect on homologous 4Fe-4S dehydratases in the cytosol. Most striking, hypoxia but not cobalt affected cellular pools of amino acids. Amino acids such as aromatics were elevated whereas leucine and methionine, essential to the strain used here, dramatically decreased due to hypoxia induced down-regulation of amino acid permeases.These studies underscore the notion that cobalt targets a specific class of iron proteins and provide the first evidence for hypoxia effects on amino acid regulation. This research illustrates the power of metabolite profiling for uncovering new adaptations to environmental stress.

Biosynthesis of GDP-fucose and other sugar nucleotides in the blood stages of Plasmodium falciparum.

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Sanz, Sílvia; Bandini, Giulia; Ospina, Diego; Bernabeu, Maria; Mariño, Karina; Fernández-Becerra, Carmen; Izquierdo, Luis

2013-06-07

Carbohydrate structures play important roles in many biological processes, including cell adhesion, cell-cell communication, and host-pathogen interactions. Sugar nucleotides are activated forms of sugars used by the cell as donors for most glycosylation reactions. Using a liquid chromatography-tandem mass spectrometry-based method, we identified and quantified the pools of UDP-glucose, UDP-galactose, UDP-N-acetylglucosamine, GDP-mannose, and GDP-fucose in Plasmodium falciparum intraerythrocytic life stages. We assembled these data with the in silico functional reconstruction of the parasite metabolic pathways obtained from the P. falciparum annotated genome, exposing new active biosynthetic routes crucial for further glycosylation reactions. Fucose is a sugar present in glycoconjugates often associated with recognition and adhesion events. Thus, the GDP-fucose precursor is essential in a wide variety of organisms. P. falciparum presents homologues of GDP-mannose 4,6-dehydratase and GDP-L-fucose synthase enzymes that are active in vitro, indicating that most GDP-fucose is formed by a de novo pathway that involves the bioconversion of GDP-mannose. Homologues for enzymes involved in a fucose salvage pathway are apparently absent in the P. falciparum genome. This is in agreement with in vivo metabolic labeling experiments showing that fucose is not significantly incorporated by the parasite. Fluorescence microscopy of epitope-tagged versions of P. falciparum GDP-mannose 4,6-dehydratase and GDP-L-fucose synthase expressed in transgenic 3D7 parasites shows that these enzymes localize in the cytoplasm of P. falciparum during the intraerythrocytic developmental cycle. Although the function of fucose in the parasite is not known, the presence of GDP-fucose suggests that the metabolite may be used for further fucosylation reactions.

Biosynthesis of GDP-fucose and Other Sugar Nucleotides in the Blood Stages of Plasmodium falciparum*

Science.gov (United States)

Sanz, Sílvia; Bandini, Giulia; Ospina, Diego; Bernabeu, Maria; Mariño, Karina; Fernández-Becerra, Carmen; Izquierdo, Luis

2013-01-01

Carbohydrate structures play important roles in many biological processes, including cell adhesion, cell-cell communication, and host-pathogen interactions. Sugar nucleotides are activated forms of sugars used by the cell as donors for most glycosylation reactions. Using a liquid chromatography-tandem mass spectrometry-based method, we identified and quantified the pools of UDP-glucose, UDP-galactose, UDP-N-acetylglucosamine, GDP-mannose, and GDP-fucose in Plasmodium falciparum intraerythrocytic life stages. We assembled these data with the in silico functional reconstruction of the parasite metabolic pathways obtained from the P. falciparum annotated genome, exposing new active biosynthetic routes crucial for further glycosylation reactions. Fucose is a sugar present in glycoconjugates often associated with recognition and adhesion events. Thus, the GDP-fucose precursor is essential in a wide variety of organisms. P. falciparum presents homologues of GDP-mannose 4,6-dehydratase and GDP-l-fucose synthase enzymes that are active in vitro, indicating that most GDP-fucose is formed by a de novo pathway that involves the bioconversion of GDP-mannose. Homologues for enzymes involved in a fucose salvage pathway are apparently absent in the P. falciparum genome. This is in agreement with in vivo metabolic labeling experiments showing that fucose is not significantly incorporated by the parasite. Fluorescence microscopy of epitope-tagged versions of P. falciparum GDP-mannose 4,6-dehydratase and GDP-l-fucose synthase expressed in transgenic 3D7 parasites shows that these enzymes localize in the cytoplasm of P. falciparum during the intraerythrocytic developmental cycle. Although the function of fucose in the parasite is not known, the presence of GDP-fucose suggests that the metabolite may be used for further fucosylation reactions. PMID:23615908

Cyanohydrin glycosides of Passiflora

DEFF Research Database (Denmark)

Jaroszewski, Jerzy W; Olafsdottir, Elin S; Wellendorph, Petrine

2002-01-01

this glycoside co-occurs with simple beta-D-glucopyranosides: tetraphyllin A, deidaclin, tetraphyllin B, volkenin, epivolkenin and taraktophyllin. P. citrina contains passicapsin, a rare glycoside with the 2,6-dideoxy-beta-D-xylo-hexopyranosyl moiety, while P. herbertiana contains tetraphyllin A, deidaclin...... Passiflora species. These alpha-hydroxyamides, presumably formed during processing of the plant material, behave as cyanogenic compounds when treated with commercial Helix pomatia crude enzyme preparation. Thus, the enzyme preparation appears to contain an amide dehydratase, which converts alpha......-hydroxyamides to cyanohydrins that liberate cyanide; this finding is of interest in connection with analysis of plant tissues and extracts using Helix pomatia enzymes....

Holocarboxylase synthetase deficiency pre and post newborn screening

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Taraka R. Donti

2016-06-01

Full Text Available Holocarboxylase synthetase deficiency is an autosomal recessive disorder of biotin metabolism resulting in multiple carboxylase deficiency. The typical presentation described in the medical literature is of neonatal onset within hours to weeks of birth with emesis, hypotonia, lethargy, seizures, metabolic ketolactic acidosis, hyperammonemia, developmental delay, skin rash and alopecia. The condition is screened for by newborn screening (NBS tandem mass spectroscopy by elevated hydroxypentanoylcarnitine on dried blood spots. Urine organic acid profile may demonstrate elevated lactic, 3-OH isovaleric, 3-OH propionic, 3-MCC, methylcitric acids, and tiglylglycine consistent with loss of function of the above carboxylases. Here we describe a cohort of patients, 2 diagnosed pre-NBS and 3 post-NBS with broad differences in initial presentation and phenotype. In addition, prior to the advent of NBS, there are isolated reports of late-onset holocarboxylase synthetase deficiency in the medical literature, which describe patients diagnosed between 1 and 8 years of life, however to our knowledge there are no reports of late-onset HCLS being missed by NBS. Also we report two cases, each with novel pathogenic variants HCLS, diagnosed at age 3 years and 21 months respectively. The first patient had a normal newborn screen whilst the second had an abnormal newborn screen but was misdiagnosed as 3-methylcrotonylcarboxylase (3-MCC deficiency and subsequently lost to follow-up until they presented again with severe metabolic acidosis.

Differential RNA-seq, Multi-Network Analysis and Metabolic Regulation Analysis of Kluyveromyces marxianus Reveals a Compartmentalised Response to Xylose.

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Du Toit W P Schabort

Full Text Available We investigated the transcriptomic response of a new strain of the yeast Kluyveromyces marxianus, in glucose and xylose media using RNA-seq. The data were explored in a number of innovative ways using a variety of networks types, pathway maps, enrichment statistics, reporter metabolites and a flux simulation model, revealing different aspects of the genome-scale response in an integrative systems biology manner. The importance of the subcellular localisation in the transcriptomic response is emphasised here, revealing new insights. As was previously reported by others using a rich medium, we show that peroxisomal fatty acid catabolism was dramatically up-regulated in a defined xylose mineral medium without fatty acids, along with mechanisms to activate fatty acids and transfer products of β-oxidation to the mitochondria. Notably, we observed a strong up-regulation of the 2-methylcitrate pathway, supporting capacity for odd-chain fatty acid catabolism. Next we asked which pathways would respond to the additional requirement for NADPH for xylose utilisation, and rationalised the unexpected results using simulations with Flux Balance Analysis. On a fundamental level, we investigated the contribution of the hierarchical and metabolic regulation levels to the regulation of metabolic fluxes. Metabolic regulation analysis suggested that genetic level regulation plays a major role in regulating metabolic fluxes in adaptation to xylose, even for the high capacity reactions, which is unexpected. In addition, isozyme switching may play an important role in re-routing of metabolic fluxes in subcellular compartments in K. marxianus.

Exploring Lactobacillus reuteri DSM20016 as a biocatalyst for transformation of longer chain 1,2-diols: Limits with microcompartment.

Science.gov (United States)

Chen, Lu; Hatti-Kaul, Rajni

2017-01-01

Lactobacillus reuteri metabolises glycerol efficiently to form 3-hydroxypropionic acid (3-HP) and 1,3-propanediol (1,3PDO) by the same mechanism as that for 1,2-propanediol (1,2PDO) conversion to propionic acid and propanol via its propanediol utilization (pdu) pathway. Pdu enzymes are encoded by the pdu-operon, which also contain genes encoding the shell proteins of the microcompartment housing the metabolic pathway. In this work the selectivity and kinetics of the reactions catalysed by L. reuteri DSM20016 Pdu enzymes glycerol dehydratase (GDH), 1,3-propanediol oxidoreductase (PduQ) and coenzyme-A acylating propionaldehyde dehydrogenase (PduP), produced recombinantly, was investigated against corresponding substrates of different chain lengths. Glycerol dehydratase exhibited activity against C2-C4 polyols, with the highest activity against glycerol and 1,2-propanediol (1,2-PDO). A double mutant of the pduC gene of GDH (PduC-S302A/Q337A) was constructed that displayed lowered activity against glycerol and 1,2PDO but extended the substrate range upto C6-diol. The best substrate for both PduQ and PduP was 3-hydroxypropanal (3HPA), although PduP exhibited nearly 10-fold higher specific activity. The enzymes also showed some activity against C3-C10 aliphatic aldehydes, with PduP having higher relative activity. Subsequently, transformation of polyols using whole cells of L. reuteri containing the wild type- and mutated GDH, respectively, confirmed the reduced activity of the mutant against glycerol and 1,2PDO, but its activity against longer substrates was negligible. In contrast, recombinant Escherichia coli BL21(DE3) cells harboring the GDH variant converted diols with up to C6 carbon chain length to their respective aldehydes, suggesting that the protein shell of the microcompartment in L. reuteri posed a barrier to the passage of longer chain substrate.

Exploring physical and chemical factors influencing the properties of recombinant prion protein and the real-time quaking-induced conversion (RT-QuIC) assay.

Science.gov (United States)

Cheng, Keding; Sloan, Angela; Avery, Kristen M; Coulthart, Michael; Carpenter, Michael; Knox, J David

2014-01-01

Real-time quaking-induced conversion (RT-QuIC), a highly specific and sensitive assay able to detect low levels of the disease-inducing isoform of the prion protein (PrP(d)) in brain tissue biopsies and cerebral spinal fluid, has great potential to become a method for diagnosing prion disease ante mortem. In order to standardize the assay method for routine analysis, an understanding of how physical and chemical factors affect the stability of the recombinant prion protein (rPrP) substrate and the RT-QuIC assay's sensitivity, specificity, and reproducibility is required. In this study, using sporadic Creutzfeldt-Jakob Disease brain homogenate to seed the reactions and an in vitro-expressed recombinant prion protein, hamster rPrP, as the substrate, the following factors affecting the RT-QuIC assay were examined: salt and substrate concentrations, substrate storage, and pH. Results demonstrated that both the generation of the quality and quantities of rPrP substrate critical to the reaction, as well as the RT-QuIC reaction itself required strict adherence to specific physical and chemical conditions. Once optimized, the RT-QuIC assay was confirmed to be a very specific and sensitive assay method for sCJD detection. Findings in this study indicate that further optimization and standardization of RT-QuIC assay is required before it can be adopted as a routine diagnostic test.

Choroba Gerstmanna-Sträusslera-Scheinkera

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Paweł P. Liberski

2011-04-01

Full Text Available Choroba Gerstmanna-Sträusslera-Scheinkera (GSS jest genetycznie uwarunkowaną chorobą wywoływaną przez priony. Jest ona unikalna, ponieważ udało się przepasażować GSS na naczelne i gryzonie przynajmniej z mózgu obarczonego mutacją kodonu 102. Tym samym jest to jedyne schorzenie jednocześnie genetycznie uwarunkowane i zakaźne, aczkolwiek natura czynnika infekcyjnego (prionu nadal stanowi przedmiot dyskusji. W obrazie klinicznym GSS dominuje postępująca ataksja móżdżkowa z towarzyszącym otępieniem i objawami piramidowo-pozapiramidowymi. Jest to jednak choroba heterogenna, o różnym obrazie klinicznym u nosicieli różnych mutacji, a nawet u nosicieli tej samej mutacji. Obraz neuropatologiczny obejmuje obecność PrPd – immunododatnich złogów amyloidu pod postacią blaszek, zwłaszcza tzw. blaszek wielordzeniowych. Istnieje kilka modeli GSS. U myszy transgenicznych z nadekspresją zmutowanego genu kodującego PrP obserwuje się spontaniczną chorobę zwyrodnieniową, pasażowalną na myszy transgeniczne o niskiej liczbie transgenu. U myszy transgenicznych uzyskanych drogą wzajemnej rekombinacji, a więc bez nadeskpresji, nie występuje choroba spontaniczna, niemniej stają się one wrażliwe na zakażenie GSS.

Homocyst(e)ine metabolism in hemodialysis patients treated with vitamins B6, B12 and folate.

Science.gov (United States)

Henning, B F; Zidek, W; Riezler, R; Graefe, U; Tepel, M

2001-03-01

Hyperhomocyst(e)inemia is commonly accepted as an independent atherosclerotic risk factor. In most hemodialysis patients, serum homocyst(e)ine is markedly elevated and may contribute to premature atherosclerosis in these patients. Whereas the beneficial effect of folate supplementation on serum homocyst(e)ine has been extensively studied, there are less detailed studies on the effects of cobalamin and pyridoxal phosphate alone, or in combination with folate. We examined the effect of a four-week course of intravenous treatment with folate (1.1 mg), cobalamin (1.0 mg), and pyridoxal phosphate (5.0 mg), administered once (group 1), twice (group 2) or thrice (group 3) weekly in 33 hemodialysis patients divided in three groups of 11 patients. All patients were followed for a further four weeks after treatment was stopped. Serum homocyst(e)ine, cobalamin, folate and pyridoxal phosphate, as well as the metabolites of homocyst(e)ine, methylmalonate, 2-methylcitrate and cystathionine, were determined before, during and after treatment. Baseline serum homocyst(e)ine correlated significantly with serum folate (P=0.0149), cobalamin (P=0.0047) and pyridoxal phosphate (P=0.0408). Correlations independent from the other metabolites or vitamins were found for methylmalonate (P=0.003) and folate (P=0.029). All regimens increased serum cobalamin significantly (in group 1 from 444 +/- 215 to 17,303 +/- 11,989 pg/ml, Pine was lowered significantly by 39.8% +/- 31.9% (Pine levels. Increasing cobalamin levels and additional treatment with folate and pyridoxal phosphate 156 may decrease serum homocyst(e)ine in the same way as high doses of folate alone.

Biochemical and functional characterization of MRA-1571 of Mycobacterium tuberculosis H37Ra and effect of its down-regulation on survival in macrophages

International Nuclear Information System (INIS)

Sharma, Rishabh; Keshari, Deepa; Singh, Kumar Sachin; Singh, Sudheer Kumar

2017-01-01

Amino acid biosynthesis has emerged as a source of new drug targets as many bacterial strains auxotrophic for amino acids fail to proliferate under in vivo conditions. Branch chain amino acids (BCAAs) are important for Mycobacterium tuberculosis (Mtb) survival and strains deficient in their biosynthesis were attenuated for growth in mice. Threonine dehydratase (IlvA) is a pyridoxal-5-phosphate (PLP) dependent enzyme that catalyzes the first step in isoleucine biosynthesis. The MRA-1571 of Mycobacterium tuberculosis H37Ra (Mtb-Ra), annotated to be coding for IlvA, was cloned, expressed and purified. Purified protein was subsequently used for developing enzyme assay and to study its biochemical properties. Also, E. coli BL21 (DE3) IlvA knockout (E. coli-ΔilvA) was developed and genetically complemented with Mtb-Ra ilvA expression construct (pET32a-ilvA) to make complemented E. coli strain (E. coli-ΔilvA + pET32a-ilvA). The E. coli-ΔilvA showed growth failure in minimal medium but growth restoration was observed in E. coli-ΔilvA + pET32a-ilvA. E. coli-ΔilvA growth was also restored in the presence of isoleucine. The IlvA localization studies detected its distribution in cell wall and membrane fractions with relatively minor presence in cytosolic fraction. Maximum IlvA expression was observed at 72 h in wild-type (WT) Mtb-Ra infecting macrophages. Also, Mtb-Ra IlvA knockdown (KD) showed reduced survival in macrophages compared to WT and complemented strain (KDC). - Highlights: • Mtb-Ra gene MRA-1571 codes for a functional threonine dehydratase (IlvA). • IlvA is pyridoxal 5’-phosphate dependent and is inhibited by isoleucine. • E. coli IlvA knockout growth can be supplemented by isoleucine or by Mtb-Ra IlvA. • The enzyme is primarily localized in cell wall and membrane fractions. • IlvA knockdown Mtb-Ra shows reduced growth in macrophages.

Characterization of the GDP-D-mannose biosynthesis pathway in Coxiella burnetii: the initial steps for GDP-β-D-virenose biosynthesis.

Science.gov (United States)

Narasaki, Craig T; Mertens, Katja; Samuel, James E

2011-01-01

Coxiella burnetii, the etiologic agent of human Q fever, is a gram-negative and naturally obligate intracellular bacterium. The O-specific polysaccharide chain (O-PS) of the lipopolysaccharide (LPS) of C. burnetii is considered a heteropolymer of the two unusual sugars β-D-virenose and dihydrohydroxystreptose and mannose. We hypothesize that GDP-D-mannose is a metabolic intermediate to GDP-β-D-virenose. GDP-D-mannose is synthesized from fructose-6-phosphate in 3 successive reactions; Isomerization to mannose-6-phosphate catalyzed by a phosphomannose isomerase (PMI), followed by conversion to mannose-1-phosphate mediated by a phosphomannomutase (PMM) and addition of GDP by a GDP-mannose pyrophosphorylase (GMP). GDP-D-mannose is then likely converted to GDP-6-deoxy-D-lyxo-hex-4-ulopyranose (GDP-Sug), a virenose intermediate, by a GDP-mannose-4,6-dehydratase (GMD). To test the validity of this pathway in C. burnetii, three open reading frames (CBU0671, CBU0294 and CBU0689) annotated as bifunctional type II PMI, as PMM or GMD were functionally characterized by complementation of corresponding E. coli mutant strains and in enzymatic assays. CBU0671, failed to complement an Escherichia coli manA (PMM) mutant strain. However, complementation of an E. coli manC (GMP) mutant strain restored capsular polysaccharide biosynthesis. CBU0294 complemented a Pseudomonas aeruginosa algC (GMP) mutant strain and showed phosphoglucomutase activity (PGM) in a pgm E. coli mutant strain. Despite the inability to complement a manA mutant, recombinant C. burnetii PMI protein showed PMM enzymatic activity in biochemical assays. CBU0689 showed dehydratase activity and determined kinetic parameters were consistent with previously reported data from other organisms. These results show the biological function of three C. burnetii LPS biosynthesis enzymes required for the formation of GDP-D-mannose and GDP-Sug. A fundamental understanding of C. burnetii genes that encode PMI, PMM and GMP is

Proteomic analysis reveals that iron availability alters the metabolic status of the pathogenic fungus Paracoccidioides brasiliensis.

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Ana F A Parente

Full Text Available Paracoccidioides brasiliensis is a thermodimorphic fungus and the causative agent of paracoccidioidomycosis (PCM. The ability of P. brasiliensis to uptake nutrients is fundamental for growth, but a reduction in the availability of iron and other nutrients is a host defense mechanism many pathogenic fungi must overcome. Thus, fungal mechanisms that scavenge iron from host may contribute to P. brasiliensis virulence. In order to better understand how P. brasiliensis adapts to iron starvation in the host we compared the two-dimensional (2D gel protein profile of yeast cells during iron starvation to that of iron rich condition. Protein spots were selected for comparative analysis based on the protein staining intensity as determined by image analysis. A total of 1752 protein spots were selected for comparison, and a total of 274 out of the 1752 protein spots were determined to have changed significantly in abundance due to iron depletion. Ninety six of the 274 proteins were grouped into the following functional categories; energy, metabolism, cell rescue, virulence, cell cycle, protein synthesis, protein fate, transcription, cellular communication, and cell fate. A correlation between protein and transcript levels was also discovered using quantitative RT-PCR analysis from RNA obtained from P. brasiliensis under iron restricting conditions and from yeast cells isolated from infected mouse spleens. In addition, western blot analysis and enzyme activity assays validated the differential regulation of proteins identified by 2-D gel analysis. We observed an increase in glycolytic pathway protein regulation while tricarboxylic acid cycle, glyoxylate and methylcitrate cycles, and electron transport chain proteins decreased in abundance under iron limiting conditions. These data suggest a remodeling of P. brasiliensis metabolism by prioritizing iron independent pathways.

Gene stacking of multiple traits for high yield of fermentable sugars in plant biomass

DEFF Research Database (Denmark)

Aznar, Aude; Chalvin, Camille; Shih, Patrick M.

2018-01-01

the ratio of C6 to C5 sugars in the cell wall and decreasing the lignin content are two important targets in engineering of plants that are more suitable for downstream processing for second-generation biofuel production.Results: We have studied the basic mechanisms of cell wall biosynthesis and identified...... genes involved in biosynthesis of pectic galactan, including the GALS1 galactan synthase and the UDP-galactose/UDP-rhamnose transporter URGT1. We have engineered plants with a more suitable biomass composition by applying these findings, in conjunction with synthetic biology and gene stacking tools...... to vessels where this polysaccharide is essential. Finally, the high galactan and low xylan traits were stacked with the low lignin trait obtained by expressing the QsuB gene encoding dehydroshikimate dehydratase in lignifying cells.Conclusion: The results show that approaches to increasing C6 sugar content...

Increase in the amount of erythrocyte delta-aminolevulinic acid dehydratase in workers with moderate lead exposure

International Nuclear Information System (INIS)

Fujita, H.; Sano, S.

1982-01-01

The amount of ALA-D in human erythrocytes was determined directly by radioimmunoassay or calculated from the restored activity assayed in the presence of zinc and dithiothreitol, and a good correlation was observed between the RIA-based and the restored activity-based amounts. The RIA-based amount of ALA-D in the blood of 10 normal individuals (blood lead levels of 5.6 +- 2.3 μg/100 ml: mean +- SD) and 19 lead-exposed workers (blood lead levels of 41.2 +- 10.2 μg/100 ml) was 54.1 +- 11.8 μg/ml blood and 92.3 +- 20.6 μg/ml blood, respectively, indicating an apparent increase of the enzyme amount in lead-exposed workers. A significant increase in the amount of erythrocyte ALA-D calculated from the restored activity in lead-exposed workers was observed even in the low blood lead level of 10-20 μg/100 ml, resulting in the range of blood lead level 20-40 μg/100 ml. No significant difference was observed in hematocrit and hemoglobin content between lead-exposed and non-exposed groups. These observations suggested that the increase of erythrocyte ALA-D in lead exposure was not due to anemia, which might result in the increase of young erythrocytes in peripheral blood. This increase in the amount of ALA-D in human erythrocytes might be a result of the function to overcome the inhibition of the enzyme in bone marrow cells during lead exposure, and these findings may throw light on the danger to human health of low-level lead toxicity. (orig.)

Evidence for Treatable Inborn Errors of Metabolism in a Cohort of 187 Greek Patients with Autism Spectrum Disorder (ASD

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Martha eSpilioti

2013-12-01

Full Text Available We screened for the presence of inborn errors of metabolism (IEM in 187 children (105 males; 82 females, ages 4 -14 years old who presented with confirmed features of ASD. Twelve patients (7% manifested increased 3-hydroxyisovaleric acid (3-OH-IVA excretion in urine, and minor to significant improvement in autistic features was observed in seven patients following supplementation with biotin. Five diagnoses included: Lesch Nyhan syndrome (2, succinic semialdehyde dehydrogenase (SSADH deficiency (2 and phenylketonuria (1 (2.7%. Additional metabolic disturbances suggestive of IEMs included two patients whose increased urine 3-OH-IVA was accompanied by elevated methylcitrate and lactate in sera, and 30 patients that showed abnormal glucose-loading tests. In the latter group, 16/30 patients manifested increased sera beta hydroxybutyrate (b-OH-b production and 18/30 had a paradoxical increase of sera lactate. Six patients with elevated b-OH-b in sera showed improved autistic features following implementation of a ketogenic diet. Five patients showed decreased serum ketone body production with glucose loading. Twelve of 187 patients demonstrated nonspecific MRI pathology, while 25/187 had abnormal EEG findings. Finally, family history was positive for 22/187 patients (1st or 2nd degree relative with comparable symptomatology and consanguinity was documented for 12/187 patients. Our data provide evidence for a new biomarker (3-OH-IVA and novel treatment approaches in ASD patients.Concise 1 sentence take-home message: Detailed metabolic screening in a Greek cohort of autismspectrum disorder (ASD patients revealed biomarkers (urine 3-hydroxyisovaleric acid and serum b-OH-b in 7% (13/187 of patients for whom biotin supplementation or institution of a ketogenic diet resulted in mild to significant clinical improvement in autistic features.

Initial occupational exposure to lead

Energy Technology Data Exchange (ETDEWEB)

Forni, A.; Cambiaghi, G.; Secchi, G.C.

1976-01-01

Serial chromosome and biochemical studies were carried out in 11 subjects before and during initial occupational exposure to moderate quantities of lead fumes in a storage battery plant. The rate of abnormal metaphases, mostly with chromatid and one-break chromosome aberrations, was approximately doubled after one month of work; it further increased after two months of work; remained in this range up to seven months of exposure; and then tended to decrease somewhat. Blood lead levels increased progressively in the first few months, then reached a steady state. Urinary lead and coproporphyrin levels increased sharply after one month of work, while urinary delta-aminolevulinic acid (ALA) levels increased moderately. The ALA dehydratase (ALAD) activity of red blood cells (RBCs) was reduced to almost 50 percent of the initial values after one month, decreased further in subsequent months, and remained decreased through the remainder of the study.

In Silico Studies of Mammalian δ-ALAD Interactions with Selenides and Selenoxides.

Science.gov (United States)

Andrei Nogara, Pablo; Batista Teixeira Rocha, João

2018-04-01

Previous studies have shown that the mammalian δ-aminolevulinic acid dehydratase (δ-ALAD) is inhibited by selenides and selenoxides, which can involve thiol oxidation. However, the precise molecular interaction of selenides and selenoxides with the active center of the enzyme is unknown. Here, we try to explain the interaction of selenides and the respective selenoxides with human δ-ALAD by in silico molecular docking. The in silico data indicated that Se atoms of selenoxides have higher electrophilic character than their respective selenides. Further, the presence of oxygen increased the interaction of selenoxides with the δ-ALAD active site by O…Zn coordination. The interaction of S atom from Cys124 with the Se atom indicated the importance of the nucleophilic attack of the enzyme thiolate to the organoselenium molecules. These observations help us to understand the interaction of target proteins with organoselenium compounds. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Binding of 14C-5-aminolevulinic acid to a stromal protein from developing pea chloroplasts

International Nuclear Information System (INIS)

Thayer, S.S.; Castelfranco, P.A.; Wilkinson, J.; Benson, G.

1987-01-01

14 -5-Aminolevulinic acid ( 14 C-ALA) binds to a stromal protein with an apparent molecular weight of 42-43 KD on LDS and non-denaturing gels. The reaction is rapid. Binding is inhibited by sulfhydryl reagents, mM concentrations of levulinic, dihydroxy heptanoic acids and gabaculine, 10 μM N-methylprotoporphyrin. Dicarboxilic acids, such as δKG, Glu, OAA, do not inhibit. Chloramphenicol, ATP, protoporphyrin, anoxia, light, darkness have no effect. The product, once formed, is stable to treatment with 5% conc. HCl in cold acetone. It can be chased in a second incubation with unlabeled ALA, but not with levulinic acid. No activity was detected in the subplastidic membrane fractions. Western blot analysis failed to reveal any homology between the labeled protein and either cytochrome for ALA dehydratase. This ALA-binding protein was not formed in chloroplasts isolated from fully expanded pea leaves. Therefore, it is deemed likely to participate in ALA metabolism during chloroplast development

Anaerobic 4-hydroxyproline utilization: Discovery of a new glycyl radical enzyme in the human gut microbiome uncovers a widespread microbial metabolic activity.

Science.gov (United States)

Huang, Yolanda Y; Martínez-Del Campo, Ana; Balskus, Emily P

2018-02-06

The discovery of enzymes responsible for previously unappreciated microbial metabolic pathways furthers our understanding of host-microbe and microbe-microbe interactions. We recently identified and characterized a new gut microbial glycyl radical enzyme (GRE) responsible for anaerobic metabolism of trans-4-hydroxy-l-proline (Hyp). Hyp dehydratase (HypD) catalyzes the removal of water from Hyp to generate Δ 1 -pyrroline-5-carboxylate (P5C). This enzyme is encoded in the genomes of a diverse set of gut anaerobes and is prevalent and abundant in healthy human stool metagenomes. Here, we discuss the roles HypD may play in different microbial metabolic pathways as well as the potential implications of this activity for colonization resistance and pathogenesis within the human gut. Finally, we present evidence of anaerobic Hyp metabolism in sediments through enrichment culturing of Hyp-degrading bacteria, highlighting the wide distribution of this pathway in anoxic environments beyond the human gut.

PsAAT3, an oomycete-specific aspartate aminotransferase, is required for full pathogenicity of the oomycete pathogen Phytophthora sojae.

Science.gov (United States)

Wang, Rongbo; Zhang, Meixiang; Liu, Hong; Xu, Jing; Yu, Jia; He, Feng; Zhang, Xiong; Dong, Suomeng; Dou, Daolong

2016-04-01

Pathogen nutrient acquisition and metabolism are critical for successful infection and colonization. However, the nutrient requirements and metabolic pathways related to pathogenesis in oomycete pathogens are unknown. In this study, we bioinformatically identified Phytophthora sojae aspartate aminotransferases (AATs), which are key enzymes that coordinate carbon and nitrogen metabolism. We demonstrated that P. sojae encodes more AATs than the analysed fungi. Some of the AATs contained additional prephenate dehydratase and/or prephenate dehydrogenase domains in their N-termini, which are unique to oomycetes. Silencing of PsAAT3, an infection-inducible expression gene, reduced P. sojae pathogenicity on soybean plants and affected the growth under N-starving condition, suggesting that PsAAT3 is involved in pathogen pathogenicity and nitrogen utilisation during infection. Our results suggest that P. sojae and other oomycete pathogens may have distinct amino acid metabolism pathways and that PsAAT3 is important for its full pathogenicity. Copyright © 2016 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Effects of metal ions on biomass and 5-aminolevulinic acid production in Rhodopseudomonas palustris wastewater treatment.

Science.gov (United States)

Liu, Shuli; Zhang, Guangming; Li, Jianzheng; Li, Xiangkun; Zhang, Jie

2016-01-01

This work investigated the effects of eight metal ions on Rhodopseudomonas palustris growth and 5-aminolevulinic acid (ALA) yield in wastewater treatment. Results show that metal ions (Mg(2+) of 15 mmol/L, Fe(2+) of 400 μmol/L, Co(2+) of 4 μmol/L, Ni(2+) of 8 μmol/L and Zn(2+) of 4 μmol/L) could effectively improve the chemical oxygen demand (COD) removal, Rp. palustris biomass and ALA yield. The highest ALA yield of 13.1 mg/g-biomass was achieved with Fe(2+) of 400 μmol/L. ALA yields were differentially increased under different metal ions in the following order: Fe(2+) group > Mg(2+) group > Co(2+) group = Ni(2+) group > Zn(2+) group = Mo(2+) group > control. Cu(2+) and Mn(2+) inhibited Rp. palustris growth and ALA production. Mechanism analysis revealed that metal ions changed ALA yields by influencing the activities of ALA synthetase and ALA dehydratase.

Congenital myopathy is caused by mutation of HACD1.

Science.gov (United States)

Muhammad, Emad; Reish, Orit; Ohno, Yusuke; Scheetz, Todd; Deluca, Adam; Searby, Charles; Regev, Miriam; Benyamini, Lilach; Fellig, Yakov; Kihara, Akio; Sheffield, Val C; Parvari, Ruti

2013-12-20

Congenital myopathies are heterogeneous inherited diseases of muscle characterized by a range of distinctive histologic abnormalities. We have studied a consanguineous family with congenital myopathy. Genome-wide linkage analysis and whole-exome sequencing identified a homozygous non-sense mutation in 3-hydroxyacyl-CoA dehydratase 1 (HACD1) in affected individuals. The mutation results in non-sense mediated decay of the HACD1 mRNA to 31% of control levels in patient muscle and completely abrogates the enzymatic activity of dehydration of 3-hydroxyacyl-CoA, the third step in the elongation of very long-chain fatty acids (VLCFAs). We describe clinical findings correlated with a deleterious mutation in a gene not previously known to be associated with congenital myopathy in humans. We suggest that the mutation in the HACD1 gene causes a reduction in the synthesis of VLCFAs, which are components of membrane lipids and participants in physiological processes, leading to congenital myopathy. These data indicate that HACD1 is necessary for muscle function.

Members of the YjgF/YER057c/UK114 family of proteins inhibit phosphoribosylamine synthesis in vitro.

Science.gov (United States)

Lambrecht, Jennifer A; Browne, Beth Ann; Downs, Diana M

2010-11-05

The YjgF/YER057c/UK114 family of proteins is highly conserved across all three domains of life and currently lacks a consensus biochemical function. Analysis of Salmonella enterica strains lacking yjgF has led to a working model in which YjgF functions to remove potentially toxic secondary products of cellular enzymes. Strains lacking yjgF synthesize the thiamine precursor phosphoribosylamine (PRA) by a TrpD-dependent mechanism that is not present in wild-type strains. Here, PRA synthesis was reconstituted in vitro with anthranilate phosphoribosyltransferase (TrpD), threonine dehydratase (IlvA), threonine, and phosphoribosyl pyrophosphate. TrpD-dependent PRA formation in vitro was inhibited by S. enterica YjgF and the human homolog UK114. Thus, the work herein describes the first biochemical assay for diverse members of the highly conserved YjgF/YER057c/UK114 family of proteins and provides a means to dissect the cellular functions of these proteins.

Branched-chain amino acid supplementation promotes aerobic growth of Salmonella Typhimurium under nitrosative stress conditions.

Science.gov (United States)

Park, Yoon Mee; Lee, Hwa Jeong; Jeong, Jae-Ho; Kook, Joong-Ki; Choy, Hyon E; Hahn, Tae-Wook; Bang, Iel Soo

2015-12-01

Nitric oxide (NO) inactivates iron-sulfur enzymes in bacterial amino acid biosynthetic pathways, causing amino acid auxotrophy. We demonstrate that exogenous supplementation with branched-chain amino acids (BCAA) can restore the NO resistance of hmp mutant Salmonella Typhimurium lacking principal NO-metabolizing enzyme flavohemoglobin, and of mutants further lacking iron-sulfur enzymes dihydroxy-acid dehydratase (IlvD) and isopropylmalate isomerase (LeuCD) that are essential for BCAA biosynthesis, in an oxygen-dependent manner. BCAA supplementation did not affect the NO consumption rate of S. Typhimurium, suggesting the BCAA-promoted NO resistance independent of NO metabolism. BCAA supplementation also induced intracellular survival of ilvD and leuCD mutants at wild-type levels inside RAW 264.7 macrophages that produce constant amounts of NO regardless of varied supplemental BCAA concentrations. Our results suggest that the NO-induced BCAA auxotrophy of Salmonella, due to inactivation of iron-sulfur enzymes for BCAA biosynthesis, could be rescued by bacterial taking up exogenous BCAA available in oxic environments.

Effect of Glycine on Lead Mobilization, Lead-Induced Oxidative Stress, and Hepatic Toxicity in Rats

Directory of Open Access Journals (Sweden)

Yolanda Alcaraz-Contreras

2011-01-01

Full Text Available The effectiveness of glycine in treating experimental lead intoxication was examined in rats. Male Wistar rats were exposed to 3 g/L lead acetate in drinking water for 5 weeks and treated thereafter with glycine (100 and 500 mg/kg, orally once daily for 5 days or glycine (1000 mg/kg, orally once daily for 28 days. The effect of these treatments on parameters indicative of oxidative stress (glutathione and malondialdehyde levels, the activity of blood -aminolevulinic acid dehydratase, and lead concentration in blood, liver, kidney, brain, and bone were investigated. Liver samples were observed for histopathological changes. Glycine was found to be effective in (1 increasing glutathione levels; (2 reducing malondialdehyde levels; (3 decreasing lead levels in bone with the highest dose. However, glycine had no effect on lead mobilization when 100 and 500 mg/kg glycine were administered. In microscopic examination, glycine showed a protective effect against lead intoxication.

Acrolein contributes strongly to antimicrobial and heterocyclic amine transformation activities of reuterin.

Science.gov (United States)

Engels, Christina; Schwab, Clarissa; Zhang, Jianbo; Stevens, Marc J A; Bieri, Corinne; Ebert, Marc-Olivier; McNeill, Kristopher; Sturla, Shana J; Lacroix, Christophe

2016-11-07

Glycerol/diol dehydratases catalyze the conversion of glycerol to 3-hydroxypropionaldehyde (3-HPA), the basis of a multi-component system called reuterin. Reuterin has antimicrobial properties and undergoes chemical conjugation with dietary heterocyclic amines (HCAs). In aqueous solution reuterin is in dynamic equilibrium with the toxicant acrolein. It was the aim of this study to investigate the extent of acrolein formation at various physiological conditions and to determine its role in biological and chemical activities. The application of a combined novel analytical approach including IC-PAD, LC-MS and NMR together with specific acrolein scavengers suggested for the first time that acrolein, and not 3-HPA, is the active compound responsible for HCA conjugation and antimicrobial activity attributed to reuterin. As formation of the HCA conjugate was observed in vivo, our results imply that acrolein is formed in the human gut with implications on detoxification of HCAs. We propose to re-define the term reuterin to include acrolein.

Oxidative stress and neurological disorders in relation to blood lead levels in children.

Science.gov (United States)

Ahamed, M; Fareed, Mohd; Kumar, A; Siddiqui, W A; Siddiqui, M K J

2008-01-01

Oxidative stress plays a pivotal role in the pathogenesis of neurological disorders. Free radical generation appears to be the mode of lead toxicity. We evaluated the effects of blood lead levels on oxidative stress parameters in children suffering from neurological disorders. Thirty children (aged 3-12 years) with neurological disorders (cerebral palsy [n = 12], seizures [n = 11], and encephalopathy [n = 7]) were recruited in the study group. Sixty healthy children (aged 3-12 years) from similar socio-economic environments and not suffering from any chronic disease were taken as the controls. Blood lead levels and oxidant/antioxidant status were determined. Mean blood lead level was significantly higher while delta-aminolevulinic acid dehydratase (delta-ALAD) activity, a biomarker for lead exposure, was significantly lower in the study group as compared to the control group (P children with neurological disorders. Lead-induced oxidative stress as an underlying mechanism for neurological diseases in children warranted further investigation.

In silico analysis highlights the frequency and diversity of type 1 lantibiotic gene clusters in genome sequenced bacteria

LENUS (Irish Health Repository)

Marsh, Alan J

2010-11-30

Abstract Background Lantibiotics are lanthionine-containing, post-translationally modified antimicrobial peptides. These peptides have significant, but largely untapped, potential as preservatives and chemotherapeutic agents. Type 1 lantibiotics are those in which lanthionine residues are introduced into the structural peptide (LanA) through the activity of separate lanthionine dehydratase (LanB) and lanthionine synthetase (LanC) enzymes. Here we take advantage of the conserved nature of LanC enzymes to devise an in silico approach to identify potential lantibiotic-encoding gene clusters in genome sequenced bacteria. Results In total 49 novel type 1 lantibiotic clusters were identified which unexpectedly were associated with species, genera and even phyla of bacteria which have not previously been associated with lantibiotic production. Conclusions Multiple type 1 lantibiotic gene clusters were identified at a frequency that suggests that these antimicrobials are much more widespread than previously thought. These clusters represent a rich repository which can yield a large number of valuable novel antimicrobials and biosynthetic enzymes.

Phenylethynyl-butyltellurium inhibits the sulfhydryl enzyme Na+, K+ -ATPase: an effect dependent on the tellurium atom.

Science.gov (United States)

Quines, Caroline B; Rosa, Suzan G; Neto, José S S; Zeni, Gilson; Nogueira, Cristina W

2013-11-01

Organotellurium compounds are known for their toxicological effects. These effects may be associated with the chemical structure of these compounds and the oxidation state of the tellurium atom. In this context, 2-phenylethynyl-butyltellurium (PEBT) inhibits the activity of the sulfhydryl enzyme, δ-aminolevulinate dehydratase. The present study investigated on the importance of the tellurium atom in the PEBT ability to oxidize mono- and dithiols of low molecular weight and sulfhydryl enzymes in vitro. PEBT, at high micromolar concentrations, oxidized dithiothreitol (DTT) and inhibited cerebral Na(+), K(+)-ATPase activity, but did not alter the lactate dehydrogenase activity. The inhibition of cerebral Na(+), K(+)-ATPase activity was completely restored by DTT. By contrast, 2-phenylethynyl-butyl, a molecule without the tellurium atom, neither oxidized DTT nor altered the Na(+), K(+)-ATPase activity. In conclusion, the tellurium atom of PEBT is crucial for the catalytic oxidation of sulfhydryl groups from thiols of low molecular weight and from Na(+), K(+)-ATPase.

Lead concentrations and reproduction in highway-nesting barn swallows

Science.gov (United States)

Grue, C.E.; O'Shea, T.J.; Hoffman, D.J.

1984-01-01

Swallows (Hirundo rustica) collected within the right-of-way of a major Maryland highway were greater than those found in Barn Swallows nesting within a rural area. Lead concentrations in the feathers of adults from the highway colony were also greater than Lead concentrations in the carcasses and stomach contents of adult and nestling Barn those of rural adults, but concentrations in the feathers of nestlings from the two locations were similar. Activity of u-aminolevulinic acid dehydratase in red blood cells was lower in highway-nesting adults and their young than in their rural counterparts, although hemoglobin concentrations and hematocrits did not differ. The number of eggs, nestlings, and body weights of the latter at 16-18 days of age were similar in the two colonies, as were body weights of adults from the two areas. These results suggest that contamination of roadside habitats by lead from automotive emissions does not pose a serious hazard to birds that are aerial feeders.

Snapping turtles (Chelydra serpentina) as biomonitors of lead contamination of the Big River in Missouri`s Old Lead Belt

Energy Technology Data Exchange (ETDEWEB)

Overmann, S.R.; Krajicek, J.J. [Southeast Missouri State Univ., Cape Girardeau, MO (United States). Dept. of Biology

1995-04-01

The usefulness of common snapping turtles (Chelydra serpentina) as biomonitors of lead (Pb) contamination of aquatic ecosystems was assessed. Thirty-seven snapping turtles were collected from three sites on the Big River, an Ozarkian stream contaminated with Pb mine tailings. Morphometric measurements, tissue Pb concentrations (muscle, blood, bone, carapace, brain, and liver), {delta}-aminolevulinic acid dehydratase ({delta}-ALAD) activity, hematocrit, hemoglobin, plasma glucose, osmolality, and chloride ion content were measured. The data showed no effects of Pb contamination on capture success or morphological measurements. Tissue Pb concentrations were related to capture location. Hematocrit, plasma osmolality, plasma glucose, and plasma chloride ion content were not significantly different with respect to capture location. The {delta}-ALAD activity levels were decreased in turtles taken from contaminated sites. Lead levels in the Big River do not appear to be adversely affecting the snapping turtles of the river. Chelydra serpentina is a useful species for biomonitoring of Pb-contaminated aquatic environments.

Modes of Action of 3-Amino-1, 2, 4-Triazole: Current Status

Energy Technology Data Exchange (ETDEWEB)

Hilton, J. L. [United States Department of Agriculture, Belts Ville, MD (United States)

1966-05-15

3-amino-1, 2, 4-triazole (amitrole) is a selective herbicide toxic to many species of green plants and micro-organisms. The primary biochemical site of action does not appear to be the same in all organisms. Growth inhibitions are reversed by purines or, more effectively, by histidine in micro-organisms or by riboflavin in green plants. Both metabolites are products derived from purine metabolism. Therefore, a study of amitrole effects on purine metabolism in various organisms is in progress. Saccharomyces cerevisiae Meyen ex Hansen is highly sensitive to amitrole but may be protected by histidine. Amitrole inhibits incorporation of {sup 14}C from adenine-2- {sup 14}C into proteins and nucleic acids, and causes imidazoleglycerol phosphate-4C (IGP- {sup 14}C) to accumulate as a result of competitive inhibition of IGP dehydratase, one of the enzymes of the histidine biosynthetic pathway. Amitrole affinity for the enzyme is approximately 10 times that of IGP. The inhibition releases the histidine pathway from feedback control thereby permitting IGP to accumulate at the expense of the purine pool. The concept of an induced purine deficiency provides interpretation for the observation that: (a) purines provide limited protection against amitrole; (b) an inhibitor of adenine biosynthesis offers protection comparable to that of purines; and (c) that inhibition of riboflavin biosynthesis in Eremothecium ashbyii Guill. is reversed by histidine. Riboflavin protection of green plants against amitrole results primarily from chemical inactivation of amitrole by photoactivated flavins; however, some support for a physiological mechanism of protection still exists. Bacteria are approximately 1/100-th as sensitive to amitrole as yeasts. Biosynthesis of IGP dehydratase is derepressed in amitrole-treated Salmonella typhimurium (Loeffler) Cast, and Chalm. As a result of the increased enzyme level, higher concentrations of amitrole are required to affect growth. At these high

Effects of mercury and selenite on δ-aminolevulinate dehydratase activity and on selected oxidative stress parameters in rats

International Nuclear Information System (INIS)

Perottoni, Juliano; Lobato, L.P.; Silveira, Aline; Rocha, J.B.T.; Emanuelli, Tatiana

2004-01-01

The present study evaluates the effects of Na 2 SeO 3 and HgCl 2 on kidney and liver of adult rats. In vivo, HgCl 2 (17 μmol/kg, sc) reduced ascorbic acid levels in liver (∼15%), whereas in kidney it reduced ALA-D activity (∼60%) and ascorbic acid levels (∼35%) and increased TBARS content (∼50%). Na 2 SeO 3 (17 μmol/kg, sc) exposure increased the content of nonprotein thiol groups in liver (35-60%) and kidney (∼50-160%), partially prevented mercury-induced ALA-D inhibition in kidney, and completely prevented a mercury-induced increase of TBARS content and decrease of ascorbic acid levels in kidney. In vitro, HgCl 2 and Na 2 SeO 3 inhibited renal and hepatic ALA-D, while HgCl 2 increased TBARS in renal and hepatic tissue preparations. Na 2 SeO 3 increased the rate of glutathione oxidation in vitro. Results indicated that Na 2 SeO 3 protected against HgCl 2 effects in vivo (prevention of mercury interaction with thiol groups and of mercury-induced oxidative damage). In vitro, Na 2 SeO 3 did not prevent mercury effects, but potentiated ALA-D inhibition by mercury, probably due to its ability to oxidize thiol groups

Interaction of biodegradative threonine dehydratase (TD) of Escherichia coli with 8-azido-AMP, a photoaffinity analog of AMP

International Nuclear Information System (INIS)

Patil, R.V.; Datta, P.

1987-01-01

Stimulation of TD activity by AMP (Ka = 40 μM) is known to accompany the conversion of monomeric form of the enzyme to its tetramer and a decrease in the Km for threonine. In comparison, 8-azido-AMP (N 3 AMP) simulated TD activity only partially, lowered the Km for threonine and stabilized a dimeric form of the protein. Competition experiments revealed that N 3 AMP exerted an apparent dominant effect in counteracting the AMP-mediated enzyme activation, indicating complex mutual interactions between these ligands. UV irradiation of TD with increasing concentrations of 3 H-N 3 AMP (up to 150 μM) resulted in gradual loss of enzyme activity and concomitant incorporation of N 3 AMP into protein; upon complete inactivation, 0.75 mol of N 3 AMP was bound per mol tetramer. The presence of AMP during photolysis reduced the extent of enzyme inactivation as well as the incorporation of N 3 AMP into protein. Photolabeling of TD with 20 μM 3 H-N 3 AMP revealed one labeled tryptic peptide; at higher N 3 AMP concentrations (>300 μM), two labeled peptides were found, one of which was identical to that found with low N 3 AMP concentration. The cumulative results suggest that N 3 AMP can act as an allosteric modifier and that the peptide labeled at low N 3 AMP may represent the AMP binding site on the protein molecule

Influence of void defects on partial discharge behavior of superconducting busbar insulation

Energy Technology Data Exchange (ETDEWEB)

Wang, Chunyu; Huang, Xiongyi, E-mail: huangxy@ipp.ac.cn; Lu, Kun; Li, Guoliang; Zhu, Haisheng; Wang, Jun; Wang, Cao; Dai, Zhiheng; Fang, Linlin; Song, Yuntao

2017-06-15

Highlights: • PD detection method was used to check the quality of the superconducting busbar insulation. • The samples with different void fraction were manufactured for comparing. • The discharge inception voltage, PRPD pattern was tested and studied for the samples with different void content. • The PD behaviors in oil bath and air condition were compared. - Abstract: For a magnetic confinement fusion device, the superconducting magnets and busbars need to be insulated with one layer of solid insulation to isolate the high voltage potential from the ground. The insulation layer commonly consists of several interleaved layers of epoxy resin-impregnated glass fiber tapes and polyimide films. The traditional electrical inspection methods for such solidified insulation on the magnet and busbar are a DC voltage test or a Paschen test. These tests measure the quality of the insulation based on the value of leakage currents. However, even if there is a larger quantity of high dielectric strength material implemented, if there are some microcavities or delaminations in the insulation system, the leakage current may be limited to microampere levels under testing levels over dozens of kilovolts. Therefore, it is difficult to judge the insulation quality just by the magnitudes of leakage current. Under long-term operation, such imperceptible defects will worsen and finally completely break down the insulation because of partial discharge (PD) incidents. Therefore, a PD detection test is an important complement to the DC voltage and Paschen tests for magnet and busbar insulations in the field of fusion. It is known that the PD detection test is a mature technique in the electric power industry. In this paper, the PD characteristics of samples containing glass fiber-reinforced composite insulations for use with the superconducting busbar were presented and discussed. Various samples with different void contents were prepared and the PD behaviors were tested.

Influence of void defects on partial discharge behavior of superconducting busbar insulation

International Nuclear Information System (INIS)

Wang, Chunyu; Huang, Xiongyi; Lu, Kun; Li, Guoliang; Zhu, Haisheng; Wang, Jun; Wang, Cao; Dai, Zhiheng; Fang, Linlin; Song, Yuntao

2017-01-01

Highlights: • PD detection method was used to check the quality of the superconducting busbar insulation. • The samples with different void fraction were manufactured for comparing. • The discharge inception voltage, PRPD pattern was tested and studied for the samples with different void content. • The PD behaviors in oil bath and air condition were compared. - Abstract: For a magnetic confinement fusion device, the superconducting magnets and busbars need to be insulated with one layer of solid insulation to isolate the high voltage potential from the ground. The insulation layer commonly consists of several interleaved layers of epoxy resin-impregnated glass fiber tapes and polyimide films. The traditional electrical inspection methods for such solidified insulation on the magnet and busbar are a DC voltage test or a Paschen test. These tests measure the quality of the insulation based on the value of leakage currents. However, even if there is a larger quantity of high dielectric strength material implemented, if there are some microcavities or delaminations in the insulation system, the leakage current may be limited to microampere levels under testing levels over dozens of kilovolts. Therefore, it is difficult to judge the insulation quality just by the magnitudes of leakage current. Under long-term operation, such imperceptible defects will worsen and finally completely break down the insulation because of partial discharge (PD) incidents. Therefore, a PD detection test is an important complement to the DC voltage and Paschen tests for magnet and busbar insulations in the field of fusion. It is known that the PD detection test is a mature technique in the electric power industry. In this paper, the PD characteristics of samples containing glass fiber-reinforced composite insulations for use with the superconducting busbar were presented and discussed. Various samples with different void contents were prepared and the PD behaviors were tested.

Simultaneous analysis of multiple Mycobacterium tuberculosis knockdown mutants in vitro and in vivo.

Directory of Open Access Journals (Sweden)

Antje Blumenthal

2010-12-01

Full Text Available Mycobacterium tuberculosis (Mtb represents one of the most persistent bacterial threats to human health and new drugs are needed to limit its impact. Conditional knockdown mutants can help validate new drug targets, but the analysis of individual mutants is laborious and time consuming. Here, we describe quantitative DNA tags (qTags and their use to simultaneously analyze conditional Mtb knockdown mutants that allowed silencing the glyoxylate and methylcitrate cycles (via depletion of isocitrate lyase, ICL, the serine protease Rv3671c, and the core subunits of the mycobacterial proteasome, PrcB and PrcA. The impact of gene silencing in multi-strain cultures was determined by measuring the relative abundance of mutant-specific qTags with real-time PCR. This achieved accurate quantification over a broad range of qTag abundances and depletion of ICL, Rv3671c, or PrcBA resulted in the expected impairment of growth of Mtb with butyrate as the primary carbon source, survival during oxidative stress, acid stress and starvation. The impact of depleting ICL, Rv3671c, or PrcBA in multi-strain mouse infections was analyzed with two approaches. We first measured the relative abundance of mutant-specific qTags in total chromosomal DNA isolated from bacteria that were recovered from infected lungs on agar plates. We then developed a two-step amplification procedure, which allowed us to measure the abundances of individual mutants directly in infected lung tissue. Both strategies confirmed that inactivation of Rv3671c and PrcBA severely reduced persistence of Mtb in mice. The multi-strain infections furthermore suggested that silencing ICL not only prevented growth of Mtb during acute infections but also prevented survival of Mtb during chronic infections. Analyses of the ICL knockdown mutant in single-strain infections confirmed this and demonstrated that silencing of ICL during chronic infections impaired persistence of Mtb to the extent that the pathogen

Casein phosphopeptides and CaCl2 increase penicillin production and cause an increment in microbody/peroxisome proteins in Penicillium chrysogenum.

Science.gov (United States)

Domínguez-Santos, Rebeca; Kosalková, Katarina; García-Estrada, Carlos; Barreiro, Carlos; Ibáñez, Ana; Morales, Alejandro; Martín, Juan-Francisco

2017-03-06

Transport of penicillin intermediates and penicillin secretion are still poorly characterized in Penicillium chrysogenum (re-identified as Penicillium rubens). Calcium (Ca 2+ ) plays an important role in the metabolism of filamentous fungi, and casein phosphopeptides (CPP) are involved in Ca 2+ internalization. In this study we observe that the effect of CaCl 2 and CPP is additive and promotes an increase in penicillin production of up to 10-12 fold. Combination of CaCl 2 and CPP greatly promotes expression of the three penicillin biosynthetic genes. Comparative proteomic analysis by 2D-DIGE, identified 39 proteins differentially represented in P. chrysogenum Wisconsin 54-1255 after CPP/CaCl 2 addition. The most interesting group of overrepresented proteins were a peroxisomal catalase, three proteins of the methylcitrate cycle, two aminotransferases and cystationine β-synthase, which are directly or indirectly related to the formation of penicillin amino acid precursors. Importantly, two of the enzymes of the penicillin pathway (isopenicillin N synthase and isopenicillin N acyltransferase) are clearly induced after CPP/CaCl 2 addition. Most of these overrepresented proteins are either authentic peroxisomal proteins or microbody-associated proteins. This evidence suggests that addition of CPP/CaCl 2 promotes the formation of penicillin precursors and the penicillin biosynthetic enzymes in peroxisomes and vesicles, which may be involved in transport and secretion of penicillin. Penicillin biosynthesis in Penicillium chrysogenum is one of the best characterized secondary metabolism processes. However, the mechanism by which penicillin is secreted still remains to be elucidated. Taking into account the role played by Ca 2+ and CPP in the secretory pathway and considering the positive effect that Ca 2+ exerts on penicillin production, the analysis of global protein changes produced after CPP/CaCl 2 addition is very helpful to decipher the processes related to the

Differential Metabolism of a Two-Carbon Substrate by Members of the Paracoccidioides Genus

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Lilian C. Baeza

2017-11-01

Full Text Available The genus Paracoccidioides comprises known fungal pathogens of humans and can be isolated from different infection sites. Metabolic peculiarities in different members of the Paracoccidioides led us to perform proteomic studies in the presence of the two-carbon molecule acetate, which predominates in the nutrient-poor environment of the phagosome. To investigate the expression rates of proteins of different members of Paracoccidioides, including one isolate of P. lutzii (Pb01 and three isolates of P. brasiliensis (Pb03, Pb339, and PbEPM83, using sodium acetate as a carbon source, proteins were quantified using label-free and data-independent liquid chromatography-mass spectrometry. Protein profiles of the isolates were statistically analyzed, revealing proteins that were differentially expressed when the fungus was cultivated in a non-preferential carbon source rather than glucose. A total of 1,160, 1,211, 1,280, and 1,462 proteins were reproducibly identified and relatively quantified in P. lutzii and the P. brasiliensis isolates Pb03, Pb339, and PbEPM83, respectively. Notably, 526, 435, 744, and 747 proteins were differentially expressed among P. lutzii and the P. brasiliensis isolates Pb03, Pb339, and PbEPM83, respectively, with a fold-change equal to or higher than 1.5. This analysis revealed that reorganization of metabolism occurred through the induction of proteins related to gluconeogenesis, glyoxylic/glyoxylate cycle, response to stress, and degradation of amino acids in the four isolates. The following differences were observed among the isolates: higher increases in the expression levels of proteins belonging to the TCA and respiratory chain in PbEPM83 and Pb01; increase in ethanol production in Pb01; utilization of cell wall components for gluconeogenesis in Pb03 and PbEPM83; and increased β-oxidation and methylcitrate cycle proteins in Pb01and PbEPM83. Proteomic profiles indicated that the four isolates reorganized their metabolism

Blueberry (Vaccinium ashei Reade) extract ameliorates ovarian damage induced by subchronic cadmium exposure in mice: Potential δ-ALA-D involvement.

Science.gov (United States)

Izaguirry, Aryele Pinto; Soares, Melina Bucco; Vargas, Laura Musacchio; Spiazzi, Cristiano Chiapinotto; Dos Santos Brum, Daniela; Noremberg, Simone; Mendez, Andreas Sebastian Loureiro; Santos, Francielli Weber

2017-01-01

Females are born with a finite number of oocyte-containing follicles and ovary damage results in reduced fertility. Cadmium accumulates in the reproductive system, damaging it, and the cigarette smoke is a potential exposure route. Natural therapies are relevant to health benefits and disease prevention. This study verified the effect of cadmium exposure on the ovaries of mice and the blueberry extract as a potential therapy. Blueberry therapy was effective in restoring reactive species levels and δ-aminolevulinate dehydratase activity, and partially improved the viability of cadmium-disrupted follicles. This therapy was not able to restore the 17 β-hydroxysteroid dehydrogenase activity. Extract HPLC evaluation indicated the presence of quercetin, quercitrin, isoquercetin, and ascorbic acid. Ascorbic acid was the major substance and its concentration was 620.24 µg/mL. Thus, cadmium accumulates in the ovaries of mice after subchronic exposure, inducing cellular damage, and the blueberry extract possesses antioxidant properties that could protect, at least in part, the ovarian tissue from cadmium toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 188-196, 2017. © 2015 Wiley Periodicals, Inc.

Imported occupational lead poisoning: report of four cases.

Science.gov (United States)

Petracca, M; Scafa, F; Boeri, R; Flachi, Daniela; Candura, S M

2013-01-01

In most industrialized countries, occupational lead poisoning has become increasingly rare, however this metal remains a serious health hazard in the rest of the world. We observedfour male patients (aged 35 / 54 years) who had suffered recurrent abdominal pain due to recent lead exposure (for 7 to 13 months) in two Chinese battery recycling plants. On their return to Italy, three of them presented normocytic, normochromic anaemia. The diagnosis was confirmed by high lead levels in the blood and urine, decreased erythrocyte delta-aminolevulinic acid dehydratase (ALA-D), raised erythrocyte zinc protoporphyrin (ZP), and elevated urinary excretion of b-aminolevulinic acid (ALA-U) and porphyrins. Chelation with EDTA resulted in increased urinary lead excretion, improvement of the clinical picture, decreased ZP, and progressive normalization of the other lead biomarkers (Pb-B, ALA-D, ALA-U, urinary porphyrins). Temporary work in developing countries may result in imported lead poisoning. Differential diagnosis of this unusual condition requires careful medical history collection and specific toxicological analysis. Preventive measures for workers going abroad are needed.

Proteomic and biochemical basis for enhanced growth yield of Enterobacter sp. LCR1 on insoluble phosphate medium.

Science.gov (United States)

Kumar, Arvind; Rai, Lal Chand

2015-01-01

Proteomics and biochemical analyses were used to unravel the basis for higher growth yield of Enterobacter sp. LCR1 on insoluble phosphate medium compared to soluble. Proteomic analysis using 2-DE, MALDI-TOF/MS and LC-MS revealed the involvement of nine proteins. Down-regulation of fructose bisphosphate aldolase with decreased concentrations of glucose-6-phosphate and fructose-6-phosphate indicated diminished glycolysis. However, up-regulation of phosphoglycerate mutase, increase in the activities of 6-phosphogluconate dehydratase, 2-keto-3-deoxy-6-phosphogluconate aldolase and 6-phosphogluconate dehydrogenase suggested induction of Entner-Doudoroff and pentose phosphate pathways. These pathways generate sufficient energy from gluconic acid, which is also used for biosynthesis as indicated by up-regulation of elongation factor Tu, elongation factor G and protein disulfide isomerase. Increased reactive oxygen species (ROS) formation resulting from organic acid oxidation leads to overexpressed manganese superoxide dismutase and increased activities of catalase and ascorbate peroxidase. Thus the organism uses gluconate instead of glucose for energy, while alleviating extra ROS formation by oxidative defense enzymes. Copyright © 2014 Elsevier GmbH. All rights reserved.

High-sucrose diet induces diabetic-like phenotypes and oxidative stress in Drosophila melanogaster: Protective role of Syzygium cumini and Bauhinia forficata.

Science.gov (United States)

Ecker, Assis; Gonzaga, Thallita Karla Silva do Nascimento; Seeger, Rodrigo Lopes; Santos, Matheus Mulling Dos; Loreto, Julia Sepel; Boligon, Aline Augusti; Meinerz, Daiane Francine; Lugokenski, Thiago Henrique; Rocha, João Batista Teixeira da; Barbosa, Nilda Vargas

2017-05-01

Diet is a key component for development and longevity of organisms. Here, the fruit fly was used to evaluate the detrimental effects caused by consumption of high-sucrose diets (HSD), namely phenotypic responses linked to insulin signaling and oxidative stress. The protective effects of extracts from medicinal plants Syzygium cumini and Bauhinia forficata were investigated. HSD intake (15% and 30%) delayed the time to pupation and reduced the number of white pupae. In adult flies, the intake of diets was associated with mortality and increased levels of glucose+trehalose, triacylglycerols and hydrogen peroxide. Indeed, 30% HSD induced body-weight loss, mitochondrial dysfunction and changes in acetylcholinesterase, δ-aminolevulinate dehydratase and antioxidant enzymes activity. Catalase, superoxide dismutase, keap1, HSP70, dILP-5 and Insulin receptor mRNA levels were over-expressed in flies emerged from 30% HSD. The extract treatments blunted the developmental alterations elicited by diets. Syzygium cumini extract was more efficient than B. forficata in reducing hyperglycaemia, redox disturbances and the changes in mRNA expression of insulin receptor. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Clinically Important Features of Porphyrin and Heme Metabolism and the Porphyrias

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Siddesh Besur

2014-11-01

Full Text Available Heme, like chlorophyll, is a primordial molecule and is one of the fundamental pigments of life. Disorders of normal heme synthesis may cause human diseases, including certain anemias (X-linked sideroblastic anemias and porphyrias. Porphyrias are classified as hepatic and erythropoietic porphyrias based on the organ system in which heme precursors (5-aminolevulinic acid (ALA, porphobilinogen and porphyrins are chiefly overproduced. The hepatic porphyrias are further subdivided into acute porphyrias and chronic hepatic porphyrias. The acute porphyrias include acute intermittent, hereditary copro-, variegate and ALA dehydratase deficiency porphyria. Chronic hepatic porphyrias include porphyria cutanea tarda and hepatoerythropoietic porphyria. The erythropoietic porphyrias include congenital erythropoietic porphyria (Gűnther’s disease and erythropoietic protoporphyria. In this review, we summarize the key features of normal heme synthesis and its differing regulation in liver versus bone marrow. In both organs, principal regulation is exerted at the level of the first and rate-controlling enzyme, but by different molecules (heme in the liver and iron in the bone marrow. We also describe salient clinical, laboratory and genetic features of the eight types of porphyria.

Lead exposure and biological effects in pied flycatchers (Ficedula hypoleuca) before and after the closure of a lead mine in northern Sweden

International Nuclear Information System (INIS)

Berglund, A.M.M.; Ingvarsson, P.K.; Danielsson, H.; Nyholm, N.E.I.

2010-01-01

Mining activities affect the surrounding environment by increasing exposure to metals. In this study, metal accumulation and its effects on reproduction and health of pied flycatcher (Ficedula hypoleuca) nestlings were monitored before and up to five years after a lead mine and enrichment plant closed down. The lead concentration in moss, nestling blood, liver and feces all indicated decreased lead exposure by at least 31% after closure, although only blood lead decreased significantly. Although the birds responded fairly well to the changed atmospheric deposition (based on moss samples), concentrations were still higher compared with birds in a reference area, and breeding was affected at the mine (smaller clutches and higher mortality). Surviving nestlings suffered from lower hemoglobin levels, mean cell hemoglobin concentrations and inhibited δ-aminolevulinic acid dehydratase activity. Lead poisoning contributed to poor health and adverse reproductive effects, but other factors (e.g. increased parasitic load) probably also affected the birds. - Increased mortality and lower blood values in pied flycatcher (Ficedula hypoleuca) nestlings near a closed lead mine.

Effects of lead on enzymes of porphyrine biosynthesis in chloroplasts and erythrocytes

Energy Technology Data Exchange (ETDEWEB)

Hampp, R.; Kriebitzsch, C.; Ziegler, H.

1974-01-01

Two enzymes of the chlorophyll biosynthesis pathway, delta-aminolevulinic acid dehydratase (ALAD) and prophobilinogenase (PBGA), show a pronounced sensitivity to lead ion, as was shown in isolated chloroplasts of spinach. It has been reported by several authors that the activity of ALAD involved in the hemoglobine-biosynthesis in erythrocytes is also very sensitive to lead ions. Spinach chloroplasts were isolated and sonicated and the enzyme activity tested. Calf blood was collected with heparin and kept at 0/sup 0/C until enzyme determination. Hemolyzed erythrocytes (rapid freezing and thawing twice) were used as the source of enzymes. The incubation mixture was the same as for chloroplasts; the hemoglobin content per test was about 44 mg (ALAD) and 91 mg (PBGA). ALAD in erythrocytes is somewhat more sensitive to lead ions than ALAD in chloroplasts. PBGA in erythrocytes is also inhibited by Pb/sup 2 +/ ions, again more than the chloroplast enzyme. At all concentrations of Pb/sup 2 +/ checked in our experiments the percentage of inhibition was higher with PBGA. 3 references, 1 figure.

Stress response of lead-exposed rainbow trout (Oncorhynchus mykiss) during swimming performance and hypoxia challenges

Energy Technology Data Exchange (ETDEWEB)

Phillips, K.A. [National Biological Service, La Crosse, WI (United States)]|[Univ. of Wisconsin, La Crosse, WI (United States); Caldwell, C.A. [National Biological Service, La Crosse, WI (United States); Sandheinrich, M.B. [Univ. of Wisconsin, La Crosse, WI (United States)

1995-12-31

Contaminants often invoke a stress response in aquatic organisms, and may compromise their capacity to respond to secondary stressors. This may reduce growth, reproduction and survival. The authors objectives were to assess the effects of lead and secondary stressors on hematology and blood chemistry of rainbow trout. After a 7 to 8-week aqueous exposure to Pb(100{micro}g/L), rainbow trout were challenged with forced swimming or hypoxia. Lead significantly reduced concentrations of 5-aminolevulinic acid dehydratase (ALAD), but not other constituents in the blood. Lead did not affect the swimming endurance of the fish. Hematocrit, mean cell hemoglobin content, and mean cell volume were significantly lower in Pb-exposed trout following the swimming challenge. Although hypoxia resulted in increased hematocrit and plasma glucose concentrations, there were no significant differences between the Pb and control groups. Hypoxia did not affect plasma chloride concentrations, although concentrations increased in Pb-exposed trout. There was no difference in lactic acid concentrations between Pb-exposed and control fish after forced swimming or hypoxia.

Enzymatic production of microthecin by aldos-2-ulose dehydratase from 1,5-anhydro-D-fructose and stability studies of microthecin

DEFF Research Database (Denmark)

Yu, Shukun; Andreassen, Mikkel; Lundt, Inge

2008-01-01

Microthecin (2-hydroxy-2-(hydroxymethyl)-2H-pyran-3(6H)-one), which has anti-microbial activity, is one of the end products of an alternative glycogen and starch degrading pathway, the anhydrofructose pathway. It is formed from 1,5- anhydro-D-fructose (AF), a product of a-1,4-glucan lyase (EC 4...

Effects of lead exposure on oxidative stress biomarkers and plasma biochemistry in waterbirds in the field.

Science.gov (United States)

Martinez-Haro, Monica; Green, Andy J; Mateo, Rafael

2011-05-01

Medina lagoon in Andalusia has one of the highest densities of spent lead (Pb) shot in Europe. Blood samples from waterbirds were collected in 2006-2008 to measure Pb concentration (PbB), δ-aminolevulinic acid dehydratase (ALAD), oxidative stress biomarkers and plasma biochemistry. PbB above background levels (>20 μg/dl) was observed in 19% (n=59) of mallards (Anas platyrhynchos) and in all common pochards (Aythya ferina) (n=4), but common coots (Fulica atra) (n=37) and moorhens (Gallinula chloropus) (n=12) were all 6 μg/dl. In mallards, an inhibition of glutathione peroxidase (GPx) and an increased level of oxidized glutathione (oxGSH) in red blood cells (RBC) were associated with PbB levels >20 μg/dl. In coots, PbB levels were negatively related to vitamin A and carotenoid levels in plasma, and total glutathione in RBCs; and positively related with higher superoxide dismutase and GPx activities and % oxGSH in RBCs. Overall, the results indicate that previously assumed background levels of PbB for birds need to be revised. Copyright © 2011 Elsevier Inc. All rights reserved.

Molecular dissection of the role of histidine in nickel hyperaccumulation in Thalspi goesingense (Halacsy)

Energy Technology Data Exchange (ETDEWEB)

Persans, M.W.; Yan, X.; Patnoe, J.M.M.L.; Kraemer, U.; Salt, D.E.

1999-12-01

To understand the role of free histidine (His) in Ni hyperaccumulation in Thlaspi goesingense, the authors investigated the regulation of His biosynthesis at both the molecular and biochemical levels. Three T. goesingense cDNAs encoding the following His biosynthetic enzymes, ATP phosphoribosyltransferase, imidazoleglycerol phosphate dehydratase, and histidinol dehydrogenase, were isolated by functional complementation of Escherichia coli His autotrophs. Northern analysis of THJG1, THD1, and THB1 gene expression revealed that each gene is expressed in both roots and shoots, but at the concentrations and dosage times of Ni treatment used in this study, these genes failed to show any regulation by Ni. The authors were also unable to observe any increases in the concentration of free His in root, shoot, or xylem sap of T. goesingense in response to Ni exposure. X-ray absorption spectroscopy of root and shoot tissue from T. goesingense and the non-accumulator species Thlaspi reverse revealed no major differences in the coordination of Ni by His in these tissues. They therefore conclude that the Ni hyperaccumulation phenotype in T. goesingense is not determined by the overproduction of His in response to Ni.

Lead pellet retention time and associated toxicity in northern bobwhite quail (Colinus virginianus).

Science.gov (United States)

Kerr, Richard; Holladay, Steven; Jarrett, Timothy; Selcer, Barbara; Meldrum, Blair; Williams, Susan; Tannenbaum, Lawrence; Holladay, Jeremy; Williams, Jamie; Gogal, Robert

2010-12-01

Birds are exposed to Pb by oral ingestion of spent Pb shot as grit. A paucity of data exists for retention and clearance of these particles in the bird gastrointestinal tract. In the current study, northern bobwhite quail (Colinus virginianus) were orally gavaged with 1, 5, or 10 Pb shot pellets, of 2-mm diameter, and radiographically followed over time. Blood Pb levels and other measures of toxicity were collected, to correlate with pellet retention. Quail dosed with either 5 or 10 pellets exhibited morbidity between weeks 1 and 2 and were removed from further study. Most of the Pb pellets were absorbed or excreted within 14 d of gavage, independent of dose. Pellet size in the ventriculus decreased over time in radiographs, suggesting dissolution caused by the acidic pH. Birds dosed with one pellet showed mean blood Pb levels that exceeded 1,300 µg/dl at week 1, further supporting dissolution in the gastrointestinal tract. Limited signs of toxicity were seen in the one-pellet birds; however, plasma δ-aminolevulinic acid dehydratase (d-ALAD) activity was persistently depressed, suggesting possible impaired hematological function. © 2010 SETAC.

Stearoyl-acyl-carrier-protein desaturase from higher plants is structurally unrelated to the animal and fungal homologs

International Nuclear Information System (INIS)

Shanklin, J.; Somerville, C.

1991-01-01

Stearoyl-acyl-carrier-protein (ACP) desaturase was purified to homogeneity from avocado mesocarp, and monospecific polyclonal antibodies directed against the protein were used to isolate full-length cDNA clones from Ricinus communis (castor) seed and Cucumis sativus (cucumber). The nucleotide sequence of the castor clone pRCD1 revealed an open reading frame of 1.2 kilobases encoding a 396-amino acid protein of 45 kDa. The cucumber clone pCSD1 encoded a homologous 396-amino acid protein with 88% amino acid identity to the castor clone. Expression of pRCD1 in Saccharomyces cerevisiae resulted in the accumulation of a functional stearoyl-ACP desaturase, demonstrating that the introduction of this single gene product was sufficient to confer soluble desaturase activity to yeast. There was a 48-residue region of 29% amino acid sequence identity between residues 53 and 101 of the castor desaturase and the proximal border of the dehydratase region of the fatty acid synthase from yeast. Stearoyl-ACP mRNA was present at substantially higher levels in developing seeds than in leaf and root tissue, suggesting that expression of the Δ 9 desaturase is developmentally regulated

Nuclear envelope expansion is crucial for proper chromosomal segregation during a closed mitosis.

Science.gov (United States)

Takemoto, Ai; Kawashima, Shigehiro A; Li, Juan-Juan; Jeffery, Linda; Yamatsugu, Kenzo; Elemento, Olivier; Nurse, Paul

2016-03-15

Here, we screened a 10,371 library of diverse molecules using a drug-sensitive fission yeast strain to identify compounds which cause defects in chromosome segregation during mitosis. We identified a phosphorium-ylide-based compound Cutin-1 which inhibits nuclear envelope expansion and nuclear elongation during the closed mitosis of fission yeast, and showed that its target is the β-subunit of fatty acid synthase. A point mutation in the dehydratase domain of Fas1 conferred in vivo and in vitro resistance to Cutin-1. Time-lapse photomicrography showed that the bulk of the chromosomes were only transiently separated during mitosis, and nucleoli separation was defective. Subsequently sister chromatids re-associated leading to chromosomal mis-segregation. These segregation defects were reduced when the nuclear volume was increased and were increased when the nuclear volume was reduced. We propose that there needs to be sufficient nuclear volume to allow the nuclear elongation necessary during a closed mitosis to take place for proper chromosome segregation, and that inhibition of fatty acid synthase compromises nuclear elongation and leads to defects in chromosomal segregation. © 2016. Published by The Company of Biologists Ltd.

Air pollution from lead added to gasoline

Energy Technology Data Exchange (ETDEWEB)

Dingeon, B; Collombel, C

1973-01-01

General hygienic and toxicological problems of lead added to gasoline are discussed. Lead emitted by motor vehicles pollutes the air especially in cities and along highways, and is accumulated by soil and plants. The lead levels found in the blood of subjects living in cities and near highways was significantly higher than in rural dwellers. Close correlation between the atmospheric lead concentration and the carbon monoxide concentration as well as the traffic density was established, indicating traffic as the source of atmospheric lead. The effect of traffic on the atmospheric lead concentration extended over a distance of up to 4 km. The lead, emitted by motor vehicles in the form of submicron particles, is retained in the organism at rates of 5-10 percent following ingestion, and at rates of 30-50 percent when inhaled. Lead is partially excreted by the liver, kidney, hair, and nails. Some 95 percent of the retained lead is found in the blood, and accumulation in the bones with potential mobilization due to increases in the corticosteroid level was observed. Exposure to lead can be diagnosed by basophil granulation test, urine delta-aminolevulinic acid test, and delta-aminolevulinic acid dehydratase test.

Isolation and identification of new lactobacilli from goatling stomach and investigation of reuterin production in Lactobacillus reuteri strains.

Science.gov (United States)

Kiňová Sepová, Hana; Bilková, Andrea

2013-01-01

Five new strains of lactobacilli isolated from goatling's stomach were identified by molecular-biological approaches. Profiles of fermentable saccharides, Gram staining, and cell morphology were also determined. They were identified as Lactobacillus reuteri (strains KO4b, KO4m, KO5) and as Lactobacillus plantarum (strains KG1z, KG4). In DNA samples of all newly isolated L. reuteri strains as well as in L. reuteri E (Lreu E; originated from lamb), the part of gldC gene, coding large subunit of glycerol dehydratase, that is necessary for 3-hydroxypropionaldehyde (3-HPA; reuterin) production, was amplified using two designed primer sets. However, the 3-HPA production was revealed only in the strain Lreu E. It produced five- or ten-fold lower amount of 3-HPA in comparison with probiotic L. reuteri ATCC 55730 in aerobic or anaerobic conditions, respectively. Moreover, Lreu E completely lost its production ability after ca. five passages in MRS medium. The co-incubation of Lreu E, but not other L. reuteri isolates, with Escherichia coli re-induced 3-HPA production. In the case of L. reuteri ATCC 55730, the 3-HPA production increased more than four times after co-incubation with E. coli.

Regulation of melanin biosynthesis via the dihydroxynaphthalene pathway is dependent on sexual development in the ascomycete Sordaria macrospora.

Science.gov (United States)

Engh, Ines; Nowrousian, Minou; Kück, Ulrich

2007-10-01

The filamentous ascomycete Sordaria macrospora accumulates melanin during sexual development. The four melanin biosynthesis genes pks, teh, sdh and tih were isolated and their homology to genes involved in 1,8 dihydroxynaphthalene (DHN) melanin biosynthesis was shown. The presence of DHN melanin in S. macrospora was further confirmed by disrupting the pks gene encoding a putative polyketide synthase and by RNA interference-mediated silencing of the sdh gene encoding a putative scytalone dehydratase. Because melanin occurs in fruiting bodies that develop through several intermediate stages within 7 days of growth, a Northern analysis of a developmental time-course was conducted. These data revealed a time-dependent regulation of teh and sdh transcript levels. Comparing the transcriptional expression by real-time PCR of melanin biosynthesis genes in the wild type under conditions allowing or repressing sexual development, a significant downregulation during vegetative growth was detected. Quantitative real-time PCR and Northern blot analysis of melanin biosynthesis gene expression in different developmental mutants confirmed that melanin biosynthesis is linked to fruiting body development and is under the control of specific regulatory genes that participate in sexual differentiation.

Effects of environmental contaminants on snapping turtles of a tidal wetland

Energy Technology Data Exchange (ETDEWEB)

Albers, P H; Sileo, L; Mulhern, B M

1986-01-01

Snapping turtles (Chelydra serpentina) were collected from a brackish-water and a nearly freshwater area in the contaminated Hackensack Meadowlands of New Jersey and an uncontaminated freshwater area in Maryland to determine the effects of environmental contaminants on a resident wetland species. No turtles were observed or caught in Meadowlands at two trapping sites that were the most heavily contaminated by metals. Snapping turtles from the brackish-water area had an unusually low lipid content of body fat and reduced growth compared to turtles from the freshwater areas in New Jersey and Maryland. Despite the serious metal contamination of the Hackensack Meadowlands, the metal content of kidneys and livers from New Jersey turtles was low and not greatly different from that of the Maryland turtles. Organochlorine pesticide concentrations in body fat were generally low at all three study areas. Polychlorinated biphenyls (PCBs) concentrations in fat were highest in male turtles from the New Jersey brackish-water area. Analysis of blood for amino-levulinic acid dehydratase, albumin, glucose, hemoglobin, osmolatility, packed cell volume, total protein, triglycerides, and uric acid failed to reveal any differences among groups that would indicated physiological impairment related to contaminants.

Effects of environmental contaminants on snapping turtles of a tidal wetland

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Albers, P.H.; Sileo, L.; Mulhern, B.M.

1986-01-01

Snapping turtles (Chelydra serpentina) were collected from a brackish-water and a nearly freshwater area in the contaminated Hackensack Meadowlands of New Jersey and an uncontaminated freshwater area in Maryland to determine the effects of environmental contaminants on a resident wetland species. No turtles were observed or caught in the Meadowlands at two trapping sites that were the most heavily contaminated by metals. Snapping turtles from the brackish-water area had an unusually low lipid content of body fat and reduced growth compared to turtles from the fresh-water areas in New Jersey and Maryland. Despite the serious metal contamination of the Hackensack Meadowlands, the metal content of kidneys and livers from New Jersey turtles was low and not greatly different from that of the Maryland turtles. Organochlorine pesticide concentrations in body fat were generally low at all three study areas. Polychlorinated biphenyls (PCBs) concentrations in fat were highest in male turtles from the New Jersey brackish-water area. Analysis of blood for amino-levulinic acid dehydratase, albumin, glucose, hemoglobin, osmolality, packed cell volume, total protein, triglycerides, and uric acid failed to reveal any differences among groups that would indicate physiological impairment related to contaminants.

Fucosylation Is a Promising Target for Cancer Diagnosis and Therapy

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Shinichiro Shinzaki

2012-01-01

Full Text Available Oligosaccharides, sequences of carbohydrates conjugated to proteins and lipids, are arguably the most abundant and structurally diverse class of molecules. Fucosylation is one of the most important oligosaccharide modifications involved in cancer and inflammation. Recent advances in glycomics have identified several types of glyco-biomarkers containing fucosylation that are linked to certain types of cancer. Fucosylated alpha-fetoprotein (AFP is widely used in the diagnosis of hepatocellular carcinoma because it is more specific than alpha-fetoprotein. High levels of fucosylated haptoglobin have also been found in sera of patients with various carcinomas. We have recently established a simple lectin-antibody ELISA to measure fucosylated haptoglobin and to investigate its clinical use. Cellular fucosylation is dependent upon fucosyltransferase activity and the level of its donor substrate, guanosine diphosphate (GDP-fucose. GDP-mannose-4,6-dehydratase (GMDS is a key enzyme involved in the synthesis of GDP-fucose. Mutations of GMDS found in colon cancer cells induced a malignant phenotype, leading to rapid growth in athymic mice resistant to natural killer cells. This review describes the role of fucosylated haptoglobin as a cancer biomarker, and discusses the possible biological role of fucosylation in cancer development.

Elucidation of cladofulvin biosynthesis reveals a cytochrome P450 monooxygenase required for anthraquinone dimerization.

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Griffiths, Scott; Mesarich, Carl H; Saccomanno, Benedetta; Vaisberg, Abraham; De Wit, Pierre J G M; Cox, Russell; Collemare, Jérôme

2016-06-21

Anthraquinones are a large family of secondary metabolites (SMs) that are extensively studied for their diverse biological activities. These activities are determined by functional group decorations and the formation of dimers from anthraquinone monomers. Despite their numerous medicinal qualities, very few anthraquinone biosynthetic pathways have been elucidated so far, including the enzymatic dimerization steps. In this study, we report the elucidation of the biosynthesis of cladofulvin, an asymmetrical homodimer of nataloe-emodin produced by the fungus Cladosporium fulvum A gene cluster of 10 genes controls cladofulvin biosynthesis, which begins with the production of atrochrysone carboxylic acid by the polyketide synthase ClaG and the β-lactamase ClaF. This compound is decarboxylated by ClaH to yield emodin, which is then converted to chrysophanol hydroquinone by the reductase ClaC and the dehydratase ClaB. We show that the predicted cytochrome P450 ClaM catalyzes the dimerization of nataloe-emodin to cladofulvin. Remarkably, such dimerization dramatically increases nataloe-emodin cytotoxicity against mammalian cell lines. These findings shed light on the enzymatic mechanisms involved in anthraquinone dimerization. Future characterization of the ClaM enzyme should facilitate engineering the biosynthesis of novel, potent, dimeric anthraquinones and structurally related compound families.

Alleviation of isoproturon toxicity to wheat by exogenous application of glutathione.

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Nemat Alla, Mamdouh M; Hassan, Nemat M

2014-06-01

Treatment with the recommended field dose of isoproturon to 7-d-old wheat seedlings significantly decreased shoot height, fresh and dry weights during the subsequent 15days. Meanwhile contents of carotenoids, chlorophylls and anthocyanin as well as activities of δ-aminolevulinate dehydratase (ALA-D), phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) were significantly inhibited. On the other hand, the herbicide significantly increased malondialdehyde (MDA), a naturally occurring product of lipid peroxidation and H2O2, while it significantly decreased the contents of glutathione (GSH) and ascorbic acid (AsA) and reduced the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). These findings indicate an induction of a stress status in wheat seedlings following isoproturon treatment. However, exogenous GSH appeared to limit the toxic effects of isoproturon and seemed to overcome this stress status. Most likely, contents of pigment and activities of enzymes were raised to approximate control levels. Moreover, antioxidants were elevated and the oxidative stress indices seemed to be alleviated by GSH application. These results indicate that exogenous GSH enhances enzymatic and nonenzymatic antioxidants to alleviate the effects of isoproturon. Copyright © 2014 Elsevier Inc. All rights reserved.

Effects of low-level exposure to xenobiotics present in paints on oxidative stress in workers.

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Moro, Angela M; Charão, Mariele; Brucker, Natália; Bulcão, Rachel; Freitas, Fernando; Guerreiro, Gilian; Baierle, Marília; Nascimento, Sabrina; Waechter, Fernanda; Hirakata, Vânia; Linden, Rafael; Thiesen, Flávia V; Garcia, Solange Cristina

2010-09-15

Paints are composed of an extensive variety of hazardous substances, such as organic solvents and heavy metals. Biomonitoring is an essential tool for assessing the risk to occupational health. Thus, this study analyzed the levels of biomarkers of exposure for toluene, xylene, styrene, ethylbenzene, and lead, as well as the oxidative stress biomarker alterations in painters of an industry. Lipid peroxidation biomarker (MDA), delta-aminolevulinate dehydratase (ALA-D), nonprotein thyol groups, superoxide dismutase and catalase (CAT) were analyzed in exposed and nonexposed subjects. We estimated which of the paint constituents have the greatest influence on the changes in the biomarkers of oxidative stress in this case of co-exposure. The results demonstrated that despite the fact that all the biomarkers of exposure were below the biological exposure limits, the MDA levels and antioxidant enzyme activities were increased, while nonprotein thyol groups and ALA-D levels were decreased in painters when compared with nonexposed subjects. After statistic test, toluene could be suggested as the principal factor responsible for increased lipid peroxidation and inhibition of ALA-D enzyme; however, further studies on the inhibition of ALA-D enzyme by toluene are necessary. Copyright 2010 Elsevier B.V. All rights reserved.

Proteomic analysis of organic sulfur compound utilisation in Advenella mimigardefordensis strain DPN7T

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Meinert, Christina; Brandt, Ulrike; Heine, Viktoria; Beyert, Jessica; Schmidl, Sina; Wübbeler, Jan Hendrik; Voigt, Birgit; Riedel, Katharina; Steinbüchel, Alexander

2017-01-01

2-Mercaptosuccinate (MS) and 3,3´-ditiodipropionate (DTDP) were discussed as precursor substance for production of polythioesters (PTE). Therefore, degradation of MS and DTDP was investigated in Advenella mimigardefordensis strain DPN7T, applying differential proteomic analysis, gene deletion and enzyme assays. Protein extracts of cells cultivated with MS, DTDP or 3-sulfinopropionic acid (SP) were compared with those cultivated with propionate (P) and/or succinate (S). The chaperone DnaK (ratio DTDP/P 9.2, 3SP/P 4.0, MS/S 6.1, DTDP/S 6.2) and a Do-like serine protease (DegP) were increased during utilization of all organic sulfur compounds. Furthermore, a putative bacterioferritin (locus tag MIM_c12960) showed high abundance (ratio DTDP/P 5.3, 3SP/P 3.2, MS/S 4.8, DTDP/S 3.9) and is probably involved in a thiol-specific stress response. The deletion of two genes encoding transcriptional regulators (LysR (MIM_c31370) and Xre (MIM_c31360)) in the close proximity of the relevant genes of DTDP catabolism (acdA, mdo and the genes encoding the enzymes of the methylcitric acid cycle; prpC,acnD, prpF and prpB) showed that these two regulators are essential for growth of A. mimigardefordensis strain DPN7T with DTDP and that they most probably regulate transcription of genes mandatory for this catabolic pathway. Furthermore, proteome analysis revealed a high abundance (ratio MS/S 10.9) of a hypothetical cupin-2-domain containing protein (MIM_c37420). This protein shows an amino acid sequence similarity of 60% to a newly identified MS dioxygenase from Variovorax paradoxus strain B4. Deletion of the gene and the adjacently located transcriptional regulator LysR, as well as heterologous expression of MIM_c37420, the putative mercaptosuccinate dioxygenase (Msdo) from A. mimigardefordensis, showed that this protein is the key enzyme of MS degradation in A. mimigardefordensis strain DPN7T (KM 0.2 mM, specific activity 17.1 μmol mg-1 min-1) and is controlled by LysR (MIM_c37410

Genome-scale reconstruction and in silico analysis of the Ralstonia eutropha H16 for polyhydroxyalkanoate synthesis, lithoautotrophic growth, and 2-methyl citric acid production

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Kim Tae

2011-06-01

Full Text Available Abstract Background Ralstonia eutropha H16, found in both soil and water, is a Gram-negative lithoautotrophic bacterium that can utillize CO2 and H2 as its sources of carbon and energy in the absence of organic substrates. R. eutropha H16 can reach high cell densities either under lithoautotrophic or heterotrophic conditions, which makes it suitable for a number of biotechnological applications. It is the best known and most promising producer of polyhydroxyalkanoates (PHAs from various carbon substrates and is an environmentally important bacterium that can degrade aromatic compounds. In order to make R. eutropha H16 a more efficient and robust biofactory, system-wide metabolic engineering to improve its metabolic performance is essential. Thus, it is necessary to analyze its metabolic characteristics systematically and optimize the entire metabolic network at systems level. Results We present the lithoautotrophic genome-scale metabolic model of R. eutropha H16 based on the annotated genome with biochemical and physiological information. The stoichiometic model, RehMBEL1391, is composed of 1391 reactions including 229 transport reactions and 1171 metabolites. Constraints-based flux analyses were performed to refine and validate the genome-scale metabolic model under environmental and genetic perturbations. First, the lithoautotrophic growth characteristics of R. eutropha H16 were investigated under varying feeding ratios of gas mixture. Second, the genome-scale metabolic model was used to design the strategies for the production of poly[R-(--3hydroxybutyrate] (PHB under different pH values and carbon/nitrogen source uptake ratios. It was also used to analyze the metabolic characteristics of R. eutropha when the phosphofructokinase gene was expressed. Finally, in silico gene knockout simulations were performed to identify targets for metabolic engineering essential for the production of 2-methylcitric acid in R. eutropha H16. Conclusion The

Subtilomycin: A New Lantibiotic from Bacillus subtilis Strain MMA7 Isolated from the Marine Sponge Haliclona simulans

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Teresa M. Barbosa

2013-06-01

Full Text Available Bacteriocins are attracting increased attention as an alternative to classic antibiotics in the fight against infectious disease and multidrug resistant pathogens. Bacillus subtilis strain MMA7 isolated from the marine sponge Haliclona simulans displays a broad spectrum antimicrobial activity, which includes Gram-positive and Gram-negative pathogens, as well as several pathogenic Candida species. This activity is in part associated with a newly identified lantibiotic, herein named as subtilomycin. The proposed biosynthetic cluster is composed of six genes, including protein-coding genes for LanB-like dehydratase and LanC-like cyclase modification enzymes, characteristic of the class I lantibiotics. The subtilomycin biosynthetic cluster in B. subtilis strain MMA7 is found in place of the sporulation killing factor (skf operon, reported in many B. subtilis isolates and involved in a bacterial cannibalistic behaviour intended to delay sporulation. The presence of the subtilomycin biosynthetic cluster appears to be widespread amongst B. subtilis strains isolated from different shallow and deep water marine sponges. Subtilomycin possesses several desirable industrial and pharmaceutical physicochemical properties, including activity over a wide pH range, thermal resistance and water solubility. Additionally, the production of the lantibiotic subtilomycin could be a desirable property should B. subtilis strain MMA7 be employed as a probiotic in aquaculture applications.

Subtilomycin: A New Lantibiotic from Bacillus subtilis Strain MMA7 Isolated from the Marine Sponge Haliclona simulans

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Phelan, Robert W.; Barret, Matthieu; Cotter, Paul D.; O’Connor, Paula M.; Chen, Rui; Morrissey, John P.; Dobson, Alan D. W.; O’Gara, Fergal; Barbosa, Teresa M.

2013-01-01

Bacteriocins are attracting increased attention as an alternative to classic antibiotics in the fight against infectious disease and multidrug resistant pathogens. Bacillus subtilis strain MMA7 isolated from the marine sponge Haliclona simulans displays a broad spectrum antimicrobial activity, which includes Gram-positive and Gram-negative pathogens, as well as several pathogenic Candida species. This activity is in part associated with a newly identified lantibiotic, herein named as subtilomycin. The proposed biosynthetic cluster is composed of six genes, including protein-coding genes for LanB-like dehydratase and LanC-like cyclase modification enzymes, characteristic of the class I lantibiotics. The subtilomycin biosynthetic cluster in B. subtilis strain MMA7 is found in place of the sporulation killing factor (skf) operon, reported in many B. subtilis isolates and involved in a bacterial cannibalistic behaviour intended to delay sporulation. The presence of the subtilomycin biosynthetic cluster appears to be widespread amongst B. subtilis strains isolated from different shallow and deep water marine sponges. Subtilomycin possesses several desirable industrial and pharmaceutical physicochemical properties, including activity over a wide pH range, thermal resistance and water solubility. Additionally, the production of the lantibiotic subtilomycin could be a desirable property should B. subtilis strain MMA7 be employed as a probiotic in aquaculture applications. PMID:23736764

Oral lead bullet fragment exposure in northern bobwhite (Colinus virginianus).

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Kerr, Richard; Holladay, Jeremy; Holladay, Steven; Tannenbaum, Lawrence; Selcer, Barbara; Meldrum, Blair; Williams, Susan; Jarrett, Timothy; Gogal, Robert

2011-11-01

Lead (Pb) is a worldwide environmental contaminant known to adversely affect multiple organ systems in both mammalian and avian species. In birds, a common route of exposure is via oral ingestion of lead particles. Data are currently lacking for the retention and clearance of Pb bullet fragments in gastrointestinal (GI) tract of birds while linking toxicity with blood Pb levels. In the present study, northern bobwhite quail fed a seed-based diet were orally gavaged with Pb bullet fragments (zero, one or five fragments/bird) and evaluated for rate of fragment clearance, and changes in peripheral blood, renal, immune, and gastrointestinal parameters. Based on radiographs, the majority of the birds cleared or absorbed the fragments by seven days, with the exception of one five-fragment bird which took between 7 and 14 days. Blood Pb levels were higher in males than females, which may be related to egg production in females. In males but not females, feed consumption, body weight gain, packed cell volume (PCV), plasma protein concentration, and δ-aminolevulinic acid dehydratase (δ-ALAD) activity were all adversely affected by five Pb fragments. Birds of both sexes that received a single Pb fragment displayed depressed δ-ALAD, suggesting altered hematologic function, while all birds dosed with five bullet fragments exhibited greater morbidity.

Transcriptional repressor role of PocR on the 1,3-propanediol biosynthetic pathway by Lactobacillus panis PM1.

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Kang, Tae Sun; Korber, Darren R; Tanaka, Takuji

2014-06-01

The regulatory role of a transcriptional regulator (PocR) in the 1,3-propanediol biosynthetic pathway of Lactobacillus panis PM1 contributes to the optimization of 1,3-propanediol production by this strain, which potentially will lead to 1,3-propanediol manufacturing efficiencies. Lactobacillus panis PM1 can utilize a 1,3-propanediol (1,3-PDO) biosynthetic pathway, consisting of diol dehydratase (PduCDE) and 1,3-PDO dehydrogenase, as a NADH recycling system, to survive under various environmental conditions. In this study, we identified a key transcriptional repressor (PocR) which was annotated as a transcriptional factor of AraC family as part of the 1,3-PDO biosynthetic pathway of L. panis PM1. The over-expression of the PocR gene resulted in the significant repression (81 %) of pduC (PduCDE large subunit) transcription, and subsequently, the decreased activity of PduCDE by 22 %. As a result of the regulation of PduCDE, production of both 3-hydroxypropionaldehyde and 1,3-PDO in the PocR over-expressing strain were significantly decreased by 40 % relative to the control strain. These results clearly demonstrate the transcriptional repressor role of PocR in the 1,3-PDO biosynthetic pathway.

Effect of short-term administration of lead to pregnant rats

Energy Technology Data Exchange (ETDEWEB)

Hubermont, G; Buchet, J P; Roels, H; Lauwerys, R

1976-03-01

Lead was administered to adult female rats in drinking water (0; 0.1; 1 and 10 ppM) for 3 weeks before mating, during pregnancy and during 3 weeks after delivery. On day 21 after delivery the mothers and their newborns were sacrificed and various parameters of blood--lead concentration (Pb-B), hematocrit (Htc), hemoglobin (Hb), free erythrocyte porphyrins (FEP), delta-aminolevulinate dehydratase (ALAD)--and tissue--ALAD, free tissue porphyrins (FTP), lead concentration (Pb-T)--were determined. In mothers a significant increase in Pb-B and Pb concentration in kidney was found in the 10 ppM group, but this increase in lead concentration was not associated with any statistically significant modification of the biochemical parameters. In newborns, lead concentration in blood and in kidney was also significantly increased in the 10 ppm group and this lead exposure was associated with a decrease of the ALAD activity in blood and an increase of FTP in kidney. On the basis of the biochemical parameters investigated it was concluded that the developing organism is more susceptible to the biological action of lead than the organism of adult animals and that the ''no-effect'' level of lead administered during pregnancy and in the neonatal period is around 1 ppM.

Capsaicin Synthesis Requires in Situ Phenylalanine and Valine Formation in in Vitro Maintained Placentas from Capsicum chinense

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Fray M. Baas-Espinola

2016-06-01

Full Text Available Capsaicinoids (CAP are nitrogenous metabolites formed from valine (Val and phenylalanine (Phe in the placentas of hot Capsicum genotypes. Placentas of Habanero peppers can incorporate inorganic nitrogen into amino acids and have the ability to secure the availability of the required amino acids for CAP biosynthesis. In order to determine the participation of the placental tissue as a supplier of these amino acids, the effects of blocking the synthesis of Val and Phe by using specific enzyme inhibitors were analyzed. Isolated placentas maintained in vitro were used to rule out external sources′ participation. Blocking Phe synthesis, through the inhibition of arogenate dehydratase, significantly decreased CAP accumulation suggesting that at least part of Phe required in this process has to be produced in situ. Chlorsulfuron inhibition of acetolactate synthase, involved in Val synthesis, decreased not only Val accumulation but also that of CAP, pointing out that the requirement for this amino acid can also be fulfilled by this tissue. The presented data demonstrates that CAP accumulation in in vitro maintained placentas can be accomplished through the in situ availability of Val and Phe and suggests that the synthesis of the fatty acid chain moiety may be a limiting factor in the biosynthesis of these alkaloids.

Effects of Bauhinia forficata Tea on Oxidative Stress and Liver Damage in Diabetic Mice.

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Salgueiro, Andréia Caroline Fernandes; Folmer, Vanderlei; da Silva, Marianne Pires; Mendez, Andreas Sebastian Loureiro; Zemolin, Ana Paula Pegoraro; Posser, Thaís; Franco, Jeferson Luis; Puntel, Robson Luiz; Puntel, Gustavo Orione

2016-01-01

This study was designed to evaluate the effects of Bauhinia forficata Link subsp. pruinosa (BF) tea on oxidative stress and liver damage in streptozotocin (STZ)-induced diabetic mice. Diabetic male mice have remained 30 days without any treatment. BF treatment started on day 31 and continued for 21 days as a drinking-water substitute. We evaluated (1) BF chemical composition; (2) glucose levels; (3) liver/body weight ratio and liver transaminases; (4) reactive oxygen species (ROS), lipid peroxidation, and protein carbonylation in liver; (5) superoxide dismutase (SOD) and catalase (CAT) activities in liver; (6) δ-aminolevulinate dehydratase (δ-ALA-D) and nonprotein thiols (NPSH) in liver; (7) Nrf2, NQO-1, and HSP70 levels in liver and pancreas. Phytochemical analyses identified four phenols compounds. Diabetic mice present high levels of NQO-1 in pancreas, increased levels of ROS and lipid peroxidation in liver, and decrease in CAT activity. BF treatment normalized all these parameters. BF did not normalize hyperglycemia, liver/body weight ratio, aspartate aminotransferase, protein carbonyl, NPSH levels, and δ-ALA-D activity. The raised oxidative stress seems to be a potential mechanism involved in liver damage in hyperglycemic conditions. Our results indicated that BF protective effect could be attributed to its antioxidant capacity, more than a hypoglycemic potential.

Effects of Bauhinia forficata Tea on Oxidative Stress and Liver Damage in Diabetic Mice

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Andréia Caroline Fernandes Salgueiro

2016-01-01

Full Text Available This study was designed to evaluate the effects of Bauhinia forficata Link subsp. pruinosa (BF tea on oxidative stress and liver damage in streptozotocin (STZ-induced diabetic mice. Diabetic male mice have remained 30 days without any treatment. BF treatment started on day 31 and continued for 21 days as a drinking-water substitute. We evaluated (1 BF chemical composition; (2 glucose levels; (3 liver/body weight ratio and liver transaminases; (4 reactive oxygen species (ROS, lipid peroxidation, and protein carbonylation in liver; (5 superoxide dismutase (SOD and catalase (CAT activities in liver; (6 δ-aminolevulinate dehydratase (δ-ALA-D and nonprotein thiols (NPSH in liver; (7 Nrf2, NQO-1, and HSP70 levels in liver and pancreas. Phytochemical analyses identified four phenols compounds. Diabetic mice present high levels of NQO-1 in pancreas, increased levels of ROS and lipid peroxidation in liver, and decrease in CAT activity. BF treatment normalized all these parameters. BF did not normalize hyperglycemia, liver/body weight ratio, aspartate aminotransferase, protein carbonyl, NPSH levels, and δ-ALA-D activity. The raised oxidative stress seems to be a potential mechanism involved in liver damage in hyperglycemic conditions. Our results indicated that BF protective effect could be attributed to its antioxidant capacity, more than a hypoglycemic potential.

In-silico Metabolome Target Analysis Towards PanC-based Antimycobacterial Agent Discovery.

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Khoshkholgh-Sima, Baharak; Sardari, Soroush; Izadi Mobarakeh, Jalal; Khavari-Nejad, Ramezan Ali

2015-01-01

Mycobacterium tuberculosis, the main cause of tuberculosis (TB), has still remained a global health crisis especially in developing countries. Tuberculosis treatment is a laborious and lengthy process with high risk of noncompliance, cytotoxicity adverse events and drug resistance in patient. Recently, there has been an alarming rise of drug resistant in TB. In this regard, it is an unmet need to develop novel antitubercular medicines that target new or more effective biochemical pathways to prevent drug resistant Mycobacterium. Integrated study of metabolic pathways through in-silico approach played a key role in antimycobacterial design process in this study. Our results suggest that pantothenate synthetase (PanC), anthranilate phosphoribosyl transferase (TrpD) and 3-isopropylmalate dehydratase (LeuD) might be appropriate drug targets. In the next step, in-silico ligand analysis was used for more detailed study of chemical tractability of targets. This was helpful to identify pantothenate synthetase (PanC, Rv3602c) as the best target for antimycobacterial design procedure. Virtual library screening on the best ligand of PanC was then performed for inhibitory ligand design. At the end, five chemical intermediates showed significant inhibition of Mycobacterium bovis with good selectivity indices (SI) ≥10 according to Tuberculosis Antimicrobial Acquisition & Coordinating Facility of US criteria for antimycobacterial screening programs.

Antioxidant, antihyperglycemic, and antidyslipidemic effects of Brazilian-native fruit extracts in an animal model of insulin resistance.

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de Souza Cardoso, Juliane; Oliveira, Pathise Souto; Bona, Natália Pontes; Vasconcellos, Flávia Aleixo; Baldissarelli, Jucimara; Vizzotto, Marcia; Soares, Mayara Sandrielly Pereira; Ramos, Vanessa Plasse; Spanevello, Roselia Maria; Lencina, Claiton Leoneti; Tavares, Rejane Giacomelli; Stefanello, Francieli Moro

2018-12-01

Insulin resistance (IR) plays an important role in the development of many diseases, such as diabetes mellitus. Therefore, the aim of the present study was to evaluate the effects of the extracts from fruits native to Brazil on metabolic parameters and hepatic oxidative markers in an animal model of insulin resistance induced by dexamethasone (DEX). Wistar rats received water or extracts of Eugenia uniflora or Psidium cattleianum, once a day for 21 days. For the last 5 days, the rats received an intraperitoneal injection of saline or DEX. DEX caused a reduction in body weight gain and relative pancreatic weight, as well as glucose intolerance, and an increase in serum glucose and triacylglycerol levels. The extracts were found to prevent hyperglycemia and hypertriglyceridemia. DEX caused an increase in the levels of thiobarbituric acid-reactive substances and reactive oxygen species production in the liver of rats, and both extracts prevented these changes. In addition, hepatic glutathione peroxidase activity was reduced by DEX. However, total thiol content and activities of catalase, superoxide dismutase, and delta-aminolevulinate dehydratase were not altered in any of the tested groups. Fruit extracts of E. uniflora and P. cattleianum exhibited considerable antihyperglycemic, antidyslipidemic, and antioxidant effects, and may be useful in the therapeutic management of alterations due to IR.

Engineering a Polyketide Synthase for In Vitro Production of Adipic Acid

Energy Technology Data Exchange (ETDEWEB)

Hagen, A; Poust, S; De Rond, T; Fortman, JL; Katz, L; Petzold, CJ; Keasling, JD

2015-10-26

Polyketides have enormous structural diversity, yet polyketide synthases (PKSs) have thus far been engineered to produce only drug candidates or derivatives thereof. Thousands of other molecules, including commodity and specialty chemicals, could be synthesized using PKSs if composing hybrid PKSs from well-characterized parts derived from natural PKSs was more efficient. Here, using modern mass spectrometry techniques as an essential part of the design–build–test cycle, we engineered a chimeric PKS to enable production one of the most widely used commodity chemicals, adipic acid. To accomplish this, we introduced heterologous reductive domains from various PKS clusters into the borrelidin PKS’ first extension module, which we previously showed produces a 3-hydroxy-adipoyl intermediate when coincubated with the loading module and a succinyl-CoA starter unit. Acyl-ACP intermediate analysis revealed an unexpected bottleneck at the dehydration step, which was overcome by introduction of a carboxyacyl-processing dehydratase domain. Appending a thioesterase to the hybrid PKS enabled the production of free adipic acid. Using acyl-intermediate based techniques to “debug” PKSs as described here, it should one day be possible to engineer chimeric PKSs to produce a variety of existing commodity and specialty chemicals, as well as thousands of chemicals that are difficult to produce from petroleum feedstocks using traditional synthetic chemistry.

γ-Oryzanol protects against acute cadmium-induced oxidative damage in mice testes.

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Spiazzi, Cristiano C; Manfredini, Vanusa; Barcellos da Silva, Fabiana E; Flores, Erico M M; Izaguirry, Aryele P; Vargas, Laura M; Soares, Melina B; Santos, Francielli W

2013-05-01

Cadmium is a non-essential heavy metal that is present at low levels mainly in food and water and also in cigar smoke. The present study evaluated the testicular damage caused by acute cadmium exposure and verified the protective role of γ-oryzanol (ORY). Mice were administrated with a single dose of 2.5mg/kg of CdCl2, and then treated with ORY (50mM in canola oil, 5mL/kg). Testes were removed after 24h and tested for lipid peroxidation (TBARS), protein carbonylation, DNA breakage, ascorbic acid, cadmium and non-proteic thiols contents, and for the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST) and δ-aminolevulic acid dehydratase (δ-ALA-D). Cadmium presented a significant alteration in all parameters, except GPx and CAT activities. Therapy reduced in a slight degree cadmium concentration in testes (around 23%). ORY restored SOD and GST activities as well as TBARS production to the control levels. Furthermore, ORY partially recovered δ-ALA-D activity inhibited by cadmium. This study provides the first evidence on the therapeutic properties of ORY in protecting against cadmium-induced testicular toxicity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Mobilisation of heavy metals into the urine by CaEDTA: relation to erythrocyte and plasma concentrations and exposure indicators.

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Araki, S; Aono, H; Murata, K

1986-09-01

To investigate the effects of calcium disodium ethylenediamine tetra-acetate (CaEDTA) on the urinary excretion, erythrocyte, and plasma concentrations and exposure indicators of seven heavy metals, CaEDTA was administered by intravenous infusion to 20 workers exposed to lead, zinc, and copper. The workers' blood lead concentrations ranged from 22 to 59 micrograms/dl (mean 38 micrograms/dl (1.8 mumol/l]. The 24 hour urinary excretion of metals after CaEDTA administration (mobilisation yield) was on average 13 times the background excretion for lead, 11 times for zinc, 3.8 times for manganese, 3.4 times for cadmium, 1.3 times for copper, and 1.1 times for chromium; no significant increase was found for mercury. The mobilisation yield of lead (MPb) was significantly correlated with whole blood and erythrocyte concentrations and the urinary excretion of lead but not with its plasma concentration; similarly, the mobilisation yield of cadmium was significantly correlated with its erythrocyte concentration. In addition, MPb was significantly correlated with intra-erythrocytic enzyme delta-aminolaevulinic acid dehydratase activity and urinary coproporphyrin excretion. The relation between the mobilisation yield of heavy metals and their body burden (and toxic signs) is discussed in the light of these findings.

Protective effect of Allium sativum (garlic) aqueous extract against lead-induced oxidative stress in the rat brain, liver, and kidney.

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Manoj Kumar, V; Henley, A K; Nelson, C J; Indumati, O; Prabhakara Rao, Y; Rajanna, S; Rajanna, B

2017-01-01

The present investigation was undertaken to evaluate the ameliorative activity of Allium sativum against lead-induced oxidative stress in the brain, liver, and kidney of male rats. Four groups of male Wistar strain rats (100-120 g) were taken: group 1 received 1000 mg/L sodium acetate and group 2 was given 1000 mg/L lead acetate through drinking water for 2 weeks. Group 3 and 4 were treated with 250 mg/kg body weight/day of A. sativum and 500 mg/kg body weight/day of A. sativum, respectively, by oral intubation for a period of 2 weeks along with lead acetate. The rats were sacrificed after treatment and the brain, liver, and kidney were isolated on ice. In the brain, four important regions namely the hippocampus, cerebellum, cerebral cortex, and brain stem were separated and used for the present investigation. Blood was also drawn by cardiac puncture and preserved in heparinized vials at 4 °C for estimation of delta-aminolevulinic acid dehydratase (ALAD) activity. The results showed a significant (p sativum resulted in tissue-specific recovery of oxidative stress parameters namely ROS, LPP, and TPCC. A. sativum treatment also restored the blood delta-ALAD activity back to control. Overall, our results indicate that A. sativum administration could be an effective antioxidant treatment strategy for lead-induced oxidative insult.

Lead-Binding Proteins: A Review

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Harvey C. Gonick

2011-01-01

Full Text Available Lead-binding proteins are a series of low molecular weight proteins, analogous to metallothionein, which segregate lead in a nontoxic form in several organs (kidney, brain, lung, liver, erythrocyte. Whether the lead-binding proteins in every organ are identical or different remains to be determined. In the erythrocyte, delta-aminolevulinic acid dehydratase (ALAD isoforms have commanded the greatest attention as proteins and enzymes that are both inhibitable and inducible by lead. ALAD-2, although it binds lead to a greater degree than ALAD-1, appears to bind lead in a less toxic form. What may be of greater significance is that a low molecular weight lead-binding protein, approximately 10 kDa, appears in the erythrocyte once blood lead exceeds 39 μg/dL and eventually surpasses the lead-binding capacity of ALAD. In brain and kidney of environmentally exposed humans and animals, a cytoplasmic lead-binding protein has been identified as thymosin β4, a 5 kDa protein. In kidney, but not brain, another lead-binding protein has been identified as acyl-CoA binding protein, a 9 kDa protein. Each of these proteins, when coincubated with liver ALAD and titrated with lead, diminishes the inhibition of ALAD by lead, verifying their ability to segregate lead in a nontoxic form.

Role of Modular Polyketide Synthases in the Production of Polyether Ladder Compounds in Ciguatoxin-Producing Gambierdiscus polynesiensis and G. excentricus (Dinophyceae).

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Kohli, Gurjeet S; Campbell, Katrina; John, Uwe; Smith, Kirsty F; Fraga, Santiago; Rhodes, Lesley L; Murray, Shauna A

2017-09-01

Gambierdiscus, a benthic dinoflagellate, produces ciguatoxins that cause the human illness Ciguatera. Ciguatoxins are polyether ladder compounds that have a polyketide origin, indicating that polyketide synthases (PKS) are involved in their production. We sequenced transcriptomes of Gambierdiscus excentricus and Gambierdiscus polynesiensis and found 264 contigs encoding single domain ketoacyl synthases (KS; G. excentricus: 106, G. polynesiensis: 143) and ketoreductases (KR; G. excentricus: 7, G. polynesiensis: 8) with sequence similarity to type I PKSs, as reported in other dinoflagellates. In addition, 24 contigs (G. excentricus: 3, G. polynesiensis: 21) encoding multiple PKS domains (forming typical type I PKSs modules) were found. The proposed structure produced by one of these megasynthases resembles a partial carbon backbone of a polyether ladder compound. Seventeen contigs encoding single domain KS, KR, s-malonyltransacylase, dehydratase and enoyl reductase with sequence similarity to type II fatty acid synthases (FAS) in plants were found. Type I PKS and type II FAS genes were distinguished based on the arrangement of domains on the contigs and their sequence similarity and phylogenetic clustering with known PKS/FAS genes in other organisms. This differentiation of PKS and FAS pathways in Gambierdiscus is important, as it will facilitate approaches to investigating toxin biosynthesis pathways in dinoflagellates. © 2017 The Author(s) Journal of Eukaryotic Microbiology © 2017 International Society of Protistologists.

In vivo functional analysis of L-rhamnose metabolic pathway in Aspergillus niger: a tool to identify the potential inducer of RhaR.

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Khosravi, Claire; Kun, Roland Sándor; Visser, Jaap; Aguilar-Pontes, María Victoria; de Vries, Ronald P; Battaglia, Evy

2017-11-06

The genes of the non-phosphorylative L-rhamnose catabolic pathway have been identified for several yeast species. In Schefferomyces stipitis, all L-rhamnose pathway genes are organized in a cluster, which is conserved in Aspergillus niger, except for the lra-4 ortholog (lraD). The A. niger cluster also contains the gene encoding the L-rhamnose responsive transcription factor (RhaR) that has been shown to control the expression of genes involved in L-rhamnose release and catabolism. In this paper, we confirmed the function of the first three putative L-rhamnose utilisation genes from A. niger through gene deletion. We explored the identity of the inducer of the pathway regulator (RhaR) through expression analysis of the deletion mutants grown in transfer experiments to L-rhamnose and L-rhamnonate. Reduced expression of L-rhamnose-induced genes on L-rhamnose in lraA and lraB deletion strains, but not on L-rhamnonate (the product of LraB), demonstrate that the inducer of the pathway is of L-rhamnonate or a compound downstream of it. Reduced expression of these genes in the lraC deletion strain on L-rhamnonate show that it is in fact a downstream product of L-rhamnonate. This work showed that the inducer of RhaR is beyond L-rhamnonate dehydratase (LraC) and is likely to be the 2-keto-3-L-deoxyrhamnonate.

Effect of chronic lead intoxication on the distribution and elimination of amoxicillin in goats.

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Soliman, Ahmed M; Abu-Basha, Ehab A; Youssef, Salah A H; Amer, Aziza M; Murphy, Patricia A; Hauck, Catherine C; Gehring, Ronette; Hsu, Walter H

2013-01-01

A study of amoxicillin pharmacokinetics was conducted in healthy goats and goats with chronic lead intoxication. The intoxicated goats had increased serum concentrations of liver enzymes (alanine aminotransferase and γ-glutamyl transferase), blood urea nitrogen, and reactivated δ-aminolevulinic acid dehydratase compared to the controls. Following intravenous amoxicillin (10 mg/kg bw) in control and lead-intoxicated goats, elimination half-lives were 4.14 and 1.26 h, respectively. The volumes of distribution based on the terminal phase were 1.19 and 0.38 L/kg, respectively, and those at steady-state were 0.54 and 0.18 L/kg, respectively. After intramuscular (IM) amoxicillin (10 mg/kg bw) in lead-intoxicated goats and control animals, the absorption, distribution, and elimination of the drug were more rapid in lead-intoxicated goats than the controls. Peak serum concentrations of 21.89 and 12.19 μg/mL were achieved at 1 h and 2 h, respectively, in lead-intoxicated and control goats. Amoxicillin bioavailability in the lead-intoxicated goats decreased 20% compared to the controls. After amoxicillin, more of the drug was excreted in the urine from lead-intoxicated goats than the controls. Our results suggested that lead intoxication in goats increases the rate of amoxicillin absorption after IM administration and distribution and elimination. Thus, lead intoxication may impair the therapeutic effectiveness of amoxicillin.

Evaluation of reuterin production in urogenital probiotic Lactobacillus reuteri RC-14.

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Cadieux, Peter; Wind, Anette; Sommer, Philip; Schaefer, Laura; Crowley, Kate; Britton, Robert A; Reid, Gregor

2008-08-01

Classified as a distinct species in 1980, Lactobacillus reuteri strains have been used in probiotic formulations for intestinal and urogenital applications. In the former, the primary mechanism of action of L. reuteri SD2112 (ATCC 55730) has been purported to be its ability to produce the antibiotic 3-hydroxypropionaldehyde (3-HPA), also known as reuterin. In the vagina, it has been postulated that probiotic Lactobacillus reuteri RC-14 does not require reuterin production but mediates a restoration of the normal microbiota via hydrogen peroxide, biosurfactant, lactic acid production, and immune modulation. The aim of the present study was to determine whether strain RC-14 produced reuterin. Using PCR and DNA dot blot analyses, numerous Lactobacillus species, including RC-14, were screened for the presence of the gene encoding the large subunit of glycerol dehydratase (gldC), the enzyme responsible for reuterin production. In addition, lactobacilli were grown in glycerol-based media and both high-performance liquid chromatography and a colorimetric assay were used to test for the presence of reuterin. L. reuteri RC-14 was determined to be negative for gldC sequences, as well as for the production of reuterin when cultured in the presence of glycerol. These findings support that the probiotic effects of L. reuteri RC-14, repeatedly demonstrated during numerous studies of the intestine and vagina, are independent of reuterin production.

Regulation of heme metabolism in normal and sideroblastic bone marrow cells in culture

International Nuclear Information System (INIS)

Ibraham, N.G.; Lutton, J.D.; Hoffman, R.; Levere, R.D.

1985-01-01

Heme metabolism was examined in developing in vitro erythroid colonies (CFUE) and in bone marrow samples taken directly from four normal donors and four patients with sideroblastic anemia. Maximum activities of delta-aminolevulinic acid synthase (ALAS), ALA dehydratase (ALAD), and 14 C-ALA incorporation into heme were achieved in normal marrow CFUE after 8 days of culture, whereas heme oxygenase progressively decreased to low levels of activity during the same period. Assays on nucleated bone marrow cells taken directly from patients revealed that ALAS activity was considerably reduced in idiopathic sideroblastic anemia (IASA) and X-linked sideroblastic anemia (X-SA) bone marrow specimens, whereas the activity increased more than twofold (normal levels) when cells were assayed from 8-day CFUE. In all cases, ALAD activity appeared to be within normal levels. Measurement of heme synthesis revealed that normal levels of 14 C-ALA incorporation into heme were achieved in IASA cells but were reduced in X-SA cells. In marked contrast to levels in normal cells, heme oxygenase was found to be significantly elevated (two- to fourfold) in bone marrow cells taken directly from patients with IASA and X-SA. Results from this study demonstrate that IASA and X-SA bone marrow cells have disturbances in ALAS and heme metabolism, and that erythropoiesis (CFUE) can be restored to normal levels when cells are cultured in methylcellulose

The disruption of GDP-fucose de novo biosynthesis suggests the presence of a novel fucose-containing glycoconjugate in Plasmodium asexual blood stages.

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Sanz, Sílvia; López-Gutiérrez, Borja; Bandini, Giulia; Damerow, Sebastian; Absalon, Sabrina; Dinglasan, Rhoel R; Samuelson, John; Izquierdo, Luis

2016-11-16

Glycosylation is an important posttranslational protein modification in all eukaryotes. Besides glycosylphosphatidylinositol (GPI) anchors and N-glycosylation, O-fucosylation has been recently reported in key sporozoite proteins of the malaria parasite. Previous analyses showed the presence of GDP-fucose (GDP-Fuc), the precursor for all fucosylation reactions, in the blood stages of Plasmodium falciparum. The GDP-Fuc de novo pathway, which requires the action of GDP-mannose 4,6-dehydratase (GMD) and GDP-L-fucose synthase (FS), is conserved in the parasite genome, but the importance of fucose metabolism for the parasite is unknown. To functionally characterize the pathway we generated a PfGMD mutant and analyzed its phenotype. Although the labelling by the fucose-binding Ulex europaeus agglutinin I (UEA-I) was completely abrogated, GDP-Fuc was still detected in the mutant. This unexpected result suggests the presence of an alternative mechanism for maintaining GDP-Fuc in the parasite. Furthermore, PfGMD null mutant exhibited normal growth and invasion rates, revealing that the GDP-Fuc de novo metabolic pathway is not essential for the development in culture of the malaria parasite during the asexual blood stages. Nonetheless, the function of this metabolic route and the GDP-Fuc pool that is generated during this stage may be important for gametocytogenesis and sporogonic development in the mosquito.

Rescue of Notch signaling in cells incapable of GDP-L-fucose synthesis by gap junction transfer of GDP-L-fucose in Drosophila.

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Ayukawa, Tomonori; Matsumoto, Kenjiroo; Ishikawa, Hiroyuki O; Ishio, Akira; Yamakawa, Tomoko; Aoyama, Naoki; Suzuki, Takuya; Matsuno, Kenji

2012-09-18

Notch (N) is a transmembrane receptor that mediates cell-cell interactions to determine many cell-fate decisions. N contains EGF-like repeats, many of which have an O-fucose glycan modification that regulates N-ligand binding. This modification requires GDP-L-fucose as a donor of fucose. The GDP-L-fucose biosynthetic pathways are well understood, including the de novo pathway, which depends on GDP-mannose 4,6 dehydratase (Gmd) and GDP-4-keto-6-deoxy-D-mannose 3,5-epimerase/4-reductase (Gmer). However, the potential for intercellularly supplied GDP-L-fucose and the molecular basis of such transportation have not been explored in depth. To address these points, we studied the genetic effects of mutating Gmd and Gmer on fucose modifications in Drosophila. We found that these mutants functioned cell-nonautonomously, and that GDP-L-fucose was supplied intercellularly through gap junctions composed of Innexin-2. GDP-L-fucose was not supplied through body fluids from different isolated organs, indicating that the intercellular distribution of GDP-L-fucose is restricted within a given organ. Moreover, the gap junction-mediated supply of GDP-L-fucose was sufficient to support the fucosylation of N-glycans and the O-fucosylation of the N EGF-like repeats. Our results indicate that intercellular delivery is a metabolic pathway for nucleotide sugars in live animals under certain circumstances.

The disruption of GDP-fucose de novo biosynthesis suggests the presence of a novel fucose-containing glycoconjugate in Plasmodium asexual blood stages

Science.gov (United States)

Sanz, Sílvia; López-Gutiérrez, Borja; Bandini, Giulia; Damerow, Sebastian; Absalon, Sabrina; Dinglasan, Rhoel R.; Samuelson, John; Izquierdo, Luis

2016-01-01

Glycosylation is an important posttranslational protein modification in all eukaryotes. Besides glycosylphosphatidylinositol (GPI) anchors and N-glycosylation, O-fucosylation has been recently reported in key sporozoite proteins of the malaria parasite. Previous analyses showed the presence of GDP-fucose (GDP-Fuc), the precursor for all fucosylation reactions, in the blood stages of Plasmodium falciparum. The GDP-Fuc de novo pathway, which requires the action of GDP-mannose 4,6-dehydratase (GMD) and GDP-L-fucose synthase (FS), is conserved in the parasite genome, but the importance of fucose metabolism for the parasite is unknown. To functionally characterize the pathway we generated a PfGMD mutant and analyzed its phenotype. Although the labelling by the fucose-binding Ulex europaeus agglutinin I (UEA-I) was completely abrogated, GDP-Fuc was still detected in the mutant. This unexpected result suggests the presence of an alternative mechanism for maintaining GDP-Fuc in the parasite. Furthermore, PfGMD null mutant exhibited normal growth and invasion rates, revealing that the GDP-Fuc de novo metabolic pathway is not essential for the development in culture of the malaria parasite during the asexual blood stages. Nonetheless, the function of this metabolic route and the GDP-Fuc pool that is generated during this stage may be important for gametocytogenesis and sporogonic development in the mosquito. PMID:27849032

Regulation of Anthocyanin Biosynthesis in Purple Leaves of Zijuan Tea (Camellia sinensis var. kitamura

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Lingxia Wang

2017-04-01

Full Text Available Plant anthocyanin biosynthesis is well understood, but the regulatory mechanism in purple foliage tea remains unclear. Using isobaric tag for relative and absolute quantification (iTRAQ, 815 differential proteins were identified in the leaves of Zijuan tea, among which 20 were associated with the regulation of anthocyanin metabolism. We found that the abundances of anthocyanin synthesis-related enzymes such as chalcone synthase, chalcone isomerase, dihydroflavonol 4-reductase and anthocyanin synthetase, as well as anthocyanin accumulation-related UDP-glucosyl transferase and ATP-binding cassette (ABC transporters in the purple leaves were all significantly higher than those in the green leaves. The abundances of the transcription factors bHLH and HY5, regulating anthocyanin biosynthesis at transcriptional level were also obviously higher in purple leaves than those in green leaves. In addition, bifunctional 3-dehydroquinate dehydratase and chorismate mutase in purple leaves were distinctly higher in abundance compared to green leaves, which provided sufficient phenylalanine substrate for anthocyanin synthesis. Furthermore, lignin synthesis was found to be reduced due to the lower abundances of cinnamoyl-CoA reductase 1, peroxidase 15 and laccase-6, which resulted in increase of intermediates flow into anthocyanin synthesis pathway. The physiological data were consistent with proteomic results. These four aspects of biosynthetic regulation contribute to anthocyanin accumulation in purple leaves of Zijuan tea.

Antidepressant-like effect of a new selenium-containing compound is accompanied by a reduction of neuroinflammation and oxidative stress in lipopolysaccharide-challenged mice.

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Casaril, Angela M; Domingues, Micaela; Fronza, Mariana; Vieira, Beatriz; Begnini, Karine; Lenardão, Eder J; Seixas, Fabiana K; Collares, Tiago; Nogueira, Cristina W; Savegnago, Lucielli

2017-09-01

Organoselenium compounds and indoles have gained attention due to their wide range of pharmacological properties. Depression is a recurrent and disabling psychiatric illness and current evidences support that oxidative stress and neuroinflammation are mechanisms underlying the pathophysiology of this psychiatric condition. Here, we evaluated the effect of 3-((4-chlorophenyl)selanyl)-1-methyl-1H-indole (CMI) in lipopolysaccharide (LPS)-induced depressive-like behaviour, neuroinflammation and oxidative stress in male mice. CMI pre-treatment (20 and 50 mg/kg, intragastrically) significantly attenuated LPS (0.83 mg/kg, intraperitoneally)-induced depressive-like behaviour in mice by reducing the immobility time in the tail suspension test (TST) and forced swimming test (FST). CMI pre-treatment ameliorated LPS-induced neuroinflammation by reducing the levels of interleukin (IL)-1β, IL-4 and IL-6 in the hippocampus and prefrontal cortex, as well as markers of oxidative damage. Additionally, we investigated the toxicological effects of CMI (200 mg/kg, i.g.) in the liver, kidney and brain through determination of the activity of aspartate aminotransferase (AST), alanine aminotransferase (ALT), δ-aminolevulinate dehydratase (δ-ALA-D) and creatinine levels. These biomarkers were not modified, indicating the possible absence of neuro-, hepato- and nephrotoxic effects. Our results suggest that CMI could be a therapeutic approach for the treatment of depression and other neuropsychiatric disorders associated with inflammation and oxidative stress.

Cloning and characterization of GDP-perosamine synthetase (Per) from Escherichia coli O157:H7 and synthesis of GDP-perosamine in vitro

International Nuclear Information System (INIS)

Zhao Guohui; Liu Jun; Liu Xiang; Chen Min; Zhang Houcheng; Wang, Peng George

2007-01-01

GDP-perosamine synthetase (Per, E.C. not yet classified) is important to the synthesis of Escherichia coli O157:H7 O-antigen. The mutant in per gene can disrupt the synthesis of O157 O-antigen. In this study, GDP-perosamine synthetase was cloned from E. coli O157:H7 and over-expressed in E. coli BL21 (DE3). The recombinant His-tagged Per fusion protein was a decamer with molecular weight of 431 kDa. The optimal pH value of this recombinant protein was 7.5. The divalent ions had no significant effect on Per-catalyzed reaction. The K m and K cat /K m for GDP-4-keto-6-deoxy-D-mannose were 0.09 mM and 2.1 x 10 5 M -1 S -1 , and those for L-glutamate were 2 mM and 0.52 x 10 5 M -1 S -1 , respectively. Per was used to synthesize GDP-perosamine from GDP-mannose together with recombinant GDP-mannose dehydratase (GMD, E.C. 4.2.1.47). The purified GDP-perosamine was identified by MS and NMR. In summary, this work provided a feasible approach for the synthesis of GDP-perosamine which can lead to the study of LPS biosynthesis of pathogenic E. coli O157:H7

Biochemical and hematological effects of lead ingestion in nestling American kestrels (Falco sparverius)

Science.gov (United States)

Hoffman, D.J.; Franson, J.C.; Pattee, O.H.; Bunck, C.M.; Murray, H.C.

1985-01-01

1. One-day old American kestrel (Faico sparverius) nestlings were orally dosed daily with 5 μl/g of corn oil (controls), 25, 125 or 625 mg/kg of metallic lead in corn oil for 10 days.2. Forty per cent of the nestlings receiving 625 mg/kg of lead died after 6 days and growth rates were significantly depressed in the two highest lead dosed groups. At 10 days hematocrit values were significantly lower in the two highest lead treated groups, and hemoglobin content and red blood cell (δ-aminolevulinic acid dehydratase (ALAD) activity was depressed in all lead treated groups. Plasma creatine phosphokinase decreased in the two highest treatment groups.3. Brain, liver and kidney ALAD activities, brain RNA to protein ratio and liver protein concentration decreased after lead exposure whereas liver DNA, DNA to RNA ratio and DNA to protein ratio increased. Brain monoamine oxidase and ATPase were not significantly altered.4. Measurements of the ontogeny of hematological variants and enzymes in normal development, using additional untreated nestlings, revealed decreases in red blood cell ALAD, plasma aspartate amino transferase, lactate dehydrogenase, brain DNA and RNA and liver DNA, whereas hematocrit, hemoglobin, plasma alkaline phosphatase, brain monoamine oxidase, brain ALAD and liver ALAD increased during the first 10 days of posthatching development.5. Biochemical and hematological alterations were more severe than those reported in adult kestrels or precocial young birds exposed to lead. Alterations may be due in part to delayed development.

Sphingoid bases and the serine catabolic enzyme CHA1 define a novel feedforward/feedback mechanism in the response to serine availability.

Science.gov (United States)

Montefusco, David J; Newcomb, Benjamin; Gandy, Jason L; Brice, Sarah E; Matmati, Nabil; Cowart, L Ashley; Hannun, Yusuf A

2012-03-16

Targets of bioactive sphingolipids in Saccharomyces cerevisiae were previously identified using microarray experiments focused on sphingolipid-dependent responses to heat stress. One of these heat-induced genes is the serine deamidase/dehydratase Cha1 known to be regulated by increased serine availability. This study investigated the hypothesis that sphingolipids may mediate the induction of Cha1 in response to serine availability. The results showed that inhibition of de novo synthesis of sphingolipids, pharmacologically or genetically, prevented the induction of Cha1 in response to increased serine availability. Additional studies implicated the sphingoid bases phytosphingosine and dihydrosphingosine as the likely mediators of Cha1 up-regulation. The yeast protein kinases Pkh1 and Pkh2, known sphingoid base effectors, were found to mediate CHA1 up-regulation via the transcription factor Cha4. Because the results disclosed a role for sphingolipids in negative feedback regulation of serine metabolism, we investigated the effects of disrupting this mechanism on sphingolipid levels and on cell growth. Intriguingly, exposure of the cha1Δ strain to high serine resulted in hyperaccumulation of endogenous serine and in turn a significant accumulation of sphingoid bases and ceramides. Under these conditions, the cha1Δ strain displayed a significant growth defect that was sphingolipid-dependent. Together, this work reveals a feedforward/feedback loop whereby the sphingoid bases serve as sensors of serine availability and mediate up-regulation of Cha1 in response to serine availability, which in turn regulates sphingolipid levels by limiting serine accumulation.

Toxicity of Pb-contaminated soil to Japanese quail (Coturnix japonica) and the use of the blood-dietary Pb slope in risk assessment

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Beyer, W. Nelson; Chen, Yu; Henry, Paula; May, Thomas; Mosby, David; Rattner, Barnett A.; Shearn-Bochsler, Valerie I.; Sprague, Daniel; Weber, John

2014-01-01

This study relates tissue concentrations and toxic effects of Pb in Japanese quail (Coturnix japonica) to the dietary exposure of soil-borne Pb associated with mining and smelting. From 0% to 12% contaminated soil, by weight, was added to 5 experimental diets (0.12 to 382 mg Pb/kg, dry wt) and fed to the quail for 6 weeks. Benchmark doses associated with a 50% reduction in delta-aminolevulinic acid dehydratase activity were 0.62 mg Pb/kg in the blood, dry wt, and 27 mg Pb/kg in the diet. Benchmark doses associated with a 20% increase in the concentration of erythrocyte protoporphyrin were 2.7 mg Pb/kg in the blood and 152 mg Pb/kg in the diet. The quail showed no other signs of toxicity (histopathological lesions, alterations in plasma–testosterone concentration, and body and organ weights). The relation of the blood Pb concentration to the soil Pb concentration was linear, with a slope of 0.013 mg Pb/kg of blood (dry wt) divided by mg Pb/kg of diet. We suggest that this slope is potentially useful in ecological risk assessments on birds in the same way that the intake slope factor is an important parameter in risk assessments of children exposed to Pb. The slope may also be used in a tissue-residue approach as an additional line of evidence in ecological risk assessment, supplementary to an estimate of hazard based on dietary toxicity reference values.

Exposure of insects and insectivorous birds to metals and other elements from abandoned mine tailings in three Summit County drainages, Colorado

Science.gov (United States)

Custer, Christine M.; Yang, C.; Crock, J.G.; Shearn-Bochsler, V.; Smith, K.S.; Hageman, P.L.

2009-01-01

Concentrations of 31 metals, metalloids, and other elements were measured in insects and insectivorous bird tissues from three drainages with different geochemistry and mining histories in Summit Co., Colorado, in 2003, 2004, and 2005. In insect samples, all 25 elements that were analyzed in all years increased in both Snake and Deer Creeks in the mining impacted areas compared to areas above and below the mining impacted areas. This distribution of elements was predicted from known or expected sediment contamination resulting from abandoned mine tailings in those drainages. Element concentrations in avian liver tissues were in concordance with levels in insects, that is with concentrations higher in mid-drainage areas where mine tailings were present compared to both upstream and downstream locations; these differences were not always statistically different, however. The lack of statistically significant differences in liver tissues, except for a few elements, was due to relatively small sample sizes and because many of these elements are essential and therefore well regulated by the bird's homeostatic processes. Most elements were at background concentrations in avian liver tissue except for Pb which was elevated at mid-drainage sites to levels where ??-aminolevulinic acid dehydratase activity was inhibited at other mining sites in Colorado. Lead exposure, however, was not at toxic levels. Fecal samples were not a good indication of what elements birds ingested and were potentially exposed to. ?? Springer Science+Business Media B.V. 2008.

Glycerol and environmental factors: effects on 1,3-propanediol production and NAD(+) regeneration in Lactobacillus panis PM1.

Science.gov (United States)

Kang, T S; Korber, D R; Tanaka, T

2013-10-01

This study was conducted to understand the influences of fermentation factors in NADH recycling and mechanisms of 1,3-propanediol (1,3-PDO) production in Lactobacillus panis PM1. We conducted metabolite analyses, qRT-PCR of the glycerol reductive pathway [glycerol dehydratase (DhaB) and 1,3-PDO dehydrogenase (DhaT)] and DhaT activity assays at different pH, temperature and initial glycerol concentrations. The supplementation of 150 mmol l(-1) glycerol caused a shift in NADH flux from ethanol to 1,3-PDO production, whereas 300 mol l(-1) glycerol negatively affected the regeneration of NAD(+) via 1,3-PDO production. This retardation decreased transcription levels and specific activities of DhaT. The decreased DhaT activity eventually caused the shutdown of 1,3-PDO production. Temperature and pH did not significantly affect the specific activity of DhaT, whereas expression of genes for DhaB and DhaT was activated under acidic conditions. Moreover, fresh glucose addition after its depletion could not restart the glycerol reduction, but increased ethanol production. Those environmental factors affect 1,3-PDO production in different ways through changing the expression level of enzymes and shifting the NAD(+) regeneration pathways. Our findings elucidated a key element to optimize 1,3-PDO production by Lact. panis PM1, which potentially improves 1,3-PDO manufacturing efficiencies. © 2013 The Society for Applied Microbiology.

Effect of air and water pollutants on human health

Energy Technology Data Exchange (ETDEWEB)

Rhondia, D

1973-01-01

The two basic approaches in the study of the influence of air and water pollutants on human health are reviewed. The first one is an experimental or toxicological approach, concerned with biochemical, physiological, and clinical lesions, with the mechanism of the genesis of such lesions, and with the possible relations between the toxic dose and the extent or degree of the lesions. Thus, considerable changes in the electrolyte and trace element concentrations in the organism were observed following short-term exposure to such air pollutants as ozone and nitrogen dioxide which cause emphysema in a short time. Rather stable equilibrium between the uptake and excretion of lead was established. The increase in the blood lead level is accompanied by a decrease in the aminolevulinic acid dehydratase activity, a change believed to have no functional consequence. The other, epidemiological, approach is based on the study of human populations actually exposed to pollutants in daily life. Such epidemiological studies are complicated by the large number of extraneous variables playing a significant role in such discrete effects. Epidemiological studies are concerned with the establishment of relationships between specific or nonspecific mortality and morbidity associated with the actual pollution level as compared with control areas and control populations. A qualitative relationship between the increasing pollution level and advanced date of death was determinef for populations with respiratory and cardiovascular diseases. A relationship was found between the high pollution level and the number of patients hospitalized during high-pollution in Los Angeles.

Lead exposure affects health indices in free-ranging ducks in Argentina.

Science.gov (United States)

Ferreyra, Hebe; Beldomenico, Pablo M; Marchese, Krysten; Romano, Marcelo; Caselli, Andrea; Correa, Ana I; Uhart, Marcela

2015-05-01

Numerous experiments under controlled conditions and extensive investigation of waterfowl die-offs have demonstrated that exposure to lead from spent gunshot is highly detrimental to the health of waterfowl. However, few studies have focused on examining the more subtle sub-lethal effects of lead toxicity on ducks in non-experimental settings. In our study, the health of ducks exposed to varying amounts of lead under natural conditions was assessed by correlating individual lead exposure with relevant indices of health. Based on hunter-killed wild ducks in Argentina, we measured spleen mass, body condition, examined bone marrow smears, and determined Ca and P in bone tissue. In free-ranging live-trapped ducks we determined basic hematology and aminolevulinic acid dehydratase activity. Using multivariate analyses, we found that, when controlling for the potential confounding effect of site type, year, duck species, body mass and age, lead levels in the liver were negatively associated with body condition and spleen mass. Spleen mass was also lower in ducks with higher lead levels in their bones. In live ducks, high blood lead levels were associated with low packed cell volume and red cell morphologic abnormalities. These findings suggest that, despite the lack of recorded lead-induced mortality in the region, lead exposure results in less conspicuous but still significant impacts on the health of ducks, which could have serious implications for their conservation. Moreover, this evidence further supports the need for urgently banning lead shot in the region.

Effects of occupational lead exposure.

Science.gov (United States)

Wang, Y L; Lu, P K; Chen, Z Q; Liang, Y X; Lu, Q M; Pan, Z Q; Shao, M

1985-01-01

Fifty-three workers in a battery factory, 52 solderers in a television factory, and 50 embroidery workers (a reference group) were studied. The average air lead levels of the three workplaces were 0.578 mg/m3, 0.002 mg/m3, and 0.001 mg/m3, respectively. Adverse effects in terms of clinical manifestations and biochemical criteria were evident among the battery factory workers. A significant dose-response relationship existed between the toxic effects and the air lead levels. The solderers showed no apparent abnormalities in comparison with the embroidery workers. The early clinical manifestations were dysfunction of the central nervous system, indigestion, arthralgia, and myalgia in the extremities. A positive association was observed between the prevalence of fatigue, mild abdominal pain, and arthralgia and the blood lead (PbB), urinary lead (PbU), and zinc protoporphyrin (ZPP) levels. The symptomatic threshold values of PbB, PbU, and ZPP were 30 micrograms/dl (1.5 mumol/l), 0.045 mg/l (0.2 mumol/l), and 40 micrograms/dl (0.7 mumol/l), respectively. The PbB, PbU, free erythrocyte protoporphyrin, and ZPP levels and the blood aminolevulinic dehydratase ratio could be used as indicators of lead exposure, although ZPP is preferred for a preventive monitoring program. The motor and sensory conduction velocities of the median nerve were slower in the exposed groups than in the reference group. No effects on behavioral function were observed among the solderers.

Influence of Background Genome on Enzymatic Characteristics of Yellow (Ay/-, Avy/-) Mice

Science.gov (United States)

Wolff, George L.; Pitot, Henry C.

1973-01-01

Identification of the fundamental polypeptide difference between yellow (Ay/-, Avy/-) and non-yellow mice is important for biomedical research because of the influence of the yellow genotype on normal and neoplastic growth and obesity. The complexity of the "yellow mouse syndrome" makes attainment of this objective dependent on the separation of those pleiotropic enzyme differences which are secondary, and depend on the background genome, from those which are primary, and depend primarily on the agouti locus genotype.—Four of nine hepatic enzyme activities assayed simultaneously differed between eight-week-old yellow (Ay/-, Avy/-) and non-yellow (A/-, a/a) male inbred and F1 hybrid mice. Among these four, only cytoplasmic malic enzyme activity was elevated in all yellow mice, as compared with the non-yellow sibs, regardless of background genome. Glucokinase, serine dehydratase, and tyrosine α-ketoglutarate transaminase activities were also changed in yellow mice, but these alterations depended on the background genome.—The ratio of malic enzyme activity to citrate-cleavage enzyme activity, possibly related to the altered fat metabolism of yellow mice, was influenced by background genome as well as by the yellow genotype.——Significant deviations of enzyme activities from mid-parent values among F1 hybrids were associated with particular background genomes; the number of such deviations was larger among yellow mice than among non-yellows and this difference was greater among C3H F1 hybrids than among C57BL/6 F1 hybrids. PMID:4405752

Regulatory role of XynR (YagI) in catabolism of xylonate in Escherichia coli K-12.

Science.gov (United States)

Shimada, Tomohiro; Momiyama, Eri; Yamanaka, Yuki; Watanabe, Hiroki; Yamamoto, Kaneyoshi; Ishihama, Akira

2017-12-01

The genome of Escherichia coli K-12 contains ten cryptic phages, altogether constituting about 3.6% of the genome in sequence. Among more than 200 predicted genes in these cryptic phages, 14 putative transcription factor (TF) genes exist, but their regulatory functions remain unidentified. As an initial attempt to make a breakthrough for understanding the regulatory roles of cryptic phage-encoded TFs, we tried to identify the regulatory function of CP4-6 cryptic prophage-encoded YagI with unknown function. After SELEX screening, YagI was found to bind mainly at a single site within the spacer of bidirectional transcription units, yagA (encoding another uncharacterized TF) and yagEF (encoding 2-keto-3-deoxy gluconate aldolase, and dehydratase, respectively) within this prophage region. YagEF enzymes are involved in the catabolism of xylose downstream from xylonate. We then designated YagI as XynR (regulator of xylonate catabolism), one of the rare single-target TFs. In agreement with this predicted regulatory function, the activity of XynR was suggested to be controlled by xylonate. Even though low-affinity binding sites of XynR were identified in the E. coli K-12 genome, they all were inside open reading frames, implying that the regulation network of XynR is still fixed within the CR4-6 prophage without significant influence over the host E. coli K-12. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Selected trace elements and organochlorines: some findings in blood and eggs of nesting common eiders (Somateria mollissima) from Finland

Science.gov (United States)

Franson, J. Christian; Hollmen, Tuula E.; Poppenga, Robert H.; Hario, Martti; Kilpi, Mikael; Smith, Milton R.

2000-01-01

In 1997 and 1998, we collected blood samples from nesting adult female common eiders (Somateria mollissima) at five locations in the Baltic Sea near coastal Finland and analyzed them for lead, selenium, mercury, and arsenic. Eggs were collected from three locations in 1997 for analysis of selenium, mercury, arsenic, and 17 organochlorines (OCs). Mean blood lead concentrations varied by location and year and ranged from 0.02 ppm (residues in blood on wet weight basis) to 0.12 ppm, although one bird had 14.2 ppm lead in its blood. Lead residues in the blood of eiders were positively correlated with the stage of incubation, and lead inhibited the activity of the enzyme delta-aminolevulinic acid dehydratase (ALAD) in the blood. Selenium concentrations in eider blood varied by location, with means of 1.26 to 2.86 ppm. Median residues of selenium and mercury in eider eggs were 0.55 and 0.10 ppm (residues in eggs on fresh weight basis), respectively, and concentrations of both selenium and mercury in eggs were correlated with those in blood. Median concentrations of p,pa??-dichlorodiphenyldichloroethylene in eggs ranged from 13.1 to 29.6 ppb, but all other OCs were below detection limits. The residues of contaminants that we found in eggs were below concentrations generally considered to affect avian reproduction. The negative correlation of ALAD activity with blood lead concentrations is evidence of an adverse physiological effect of lead exposure in this population.

Expression control of nitrile hydratase and amidase genes in Rhodococcus erythropolis and substrate specificities of the enzymes.

Science.gov (United States)

Rucká, Lenka; Volkova, Olga; Pavlík, Adam; Kaplan, Ondřej; Kracík, Martin; Nešvera, Jan; Martínková, Ludmila; Pátek, Miroslav

2014-06-01

Bacterial amidases and nitrile hydratases can be used for the synthesis of various intermediates and products in the chemical and pharmaceutical industries and for the bioremediation of toxic pollutants. The aim of this study was to analyze the expression of the amidase and nitrile hydratase genes of Rhodococcus erythropolis and test the stereospecific nitrile hydratase and amidase activities on chiral cyanohydrins. The nucleotide sequences of the gene clusters containing the oxd (aldoxime dehydratase), ami (amidase), nha1, nha2 (subunits of the nitrile hydratase), nhr1, nhr2, nhr3 and nhr4 (putative regulatory proteins) genes of two R. erythropolis strains, A4 and CCM2595, were determined. All genes of both of the clusters are transcribed in the same direction. RT-PCR analysis, primer extension and promoter fusions with the gfp reporter gene showed that the ami, nha1 and nha2 genes of R. erythropolis A4 form an operon transcribed from the Pami promoter and an internal Pnha promoter. The activity of Pami was found to be weakly induced when the cells grew in the presence of acetonitrile, whereas the Pnha promoter was moderately induced by both the acetonitrile or acetamide used instead of the inorganic nitrogen source. However, R. erythropolis A4 cells showed no increase in amidase and nitrile hydratase activities in the presence of acetamide or acetonitrile in the medium. R. erythropolis A4 nitrile hydratase and amidase were found to be effective at hydrolysing cyanohydrins and 2-hydroxyamides, respectively.

Inactivation of dhaD and dhaK abolishes by-product accumulation during 1,3-propanediol production in Klebsiella pneumoniae.

Science.gov (United States)

Horng, Yu-Tze; Chang, Kai-Chih; Chou, Ta-Chung; Yu, Chung-Jen; Chien, Chih-Ching; Wei, Yu-Hong; Soo, Po-Chi

2010-07-01

1,3-Propanediol (1,3-PD) can be used for the industrial synthesis of a variety of compounds, including polyesters, polyethers, and polyurethanes. 1,3-PD is generated from petrochemical and microbial sources. 1,3-Propanediol is a typical product of glycerol fermentation, while acetate, lactate, 2,3-butanediol, and ethanol also accumulate during the process. Substrate and product inhibition limit the final concentration of 1,3-propanediol in the fermentation broth. It is impossible to increase the yield of 1,3-propanediol by using the traditional whole-cell fermentation process. In this study, dhaD and dhaK, the genes for glycerol dehydrogenase and dihydroxyacetone kinase, respectively, were inactivated by homologous recombination in Klebsiella pneumoniae. The dhaD/dhaK double mutant (designated TC100), selected from 5,000 single or double cross homologous recombination mutants, was confirmed as a double cross by using polymerase chain reaction. Analysis of the cell-free supernatant with high-performance liquid chromatography revealed elimination of lactate and 2,3-butanediol, as well as ethanol accumulation in TC100, compared with the wild-type strain. Furthermore, 1,3-propanediol productivity was increased in the TC100 strain expressing glycerol dehydratase and 1,3-PDO dehydrogenase regulated by the arabinose P(BAD) promoter. The genetic engineering and medium formulation approaches used here should aid in the separation of 1,3-propanediol from lactate, 2,3-butanediol, and ethanol and lead to increased production of 1,3-propanediol in Klebsiella pneumoniae.

Adverse health effects in Canada geese (Branta canadensis) associated with waste from zinc and lead mines in the Tri-State Mining District (Kansas, Oklahoma, and Missouri, USA).

Science.gov (United States)

van der Merwe, Deon; Carpenter, James W; Nietfeld, Jerome C; Miesner, John F

2011-07-01

Lead and zinc poisoning have been recorded in a variety of bird species, including migrating waterfowl such as Canada Geese (Branta canadensis), at sites contaminated with mine waste from lead and zinc mines in the Tri-State Mining District, Kansas, Oklahoma, and Missouri, USA. The adverse health impacts from mine waste on these birds may, however, be more extensive than is apparent from incidental reports of clinical disease. To characterize health impacts from mine waste on Canada Geese that do not have observable signs of poisoning, four to eight apparently healthy birds per site were collected from four contaminated sites and an uncontaminated reference site, and examined for physical and physiologic evidence of metals poisoning. Tissue concentrations of silver, aluminum, arsenic, barium, cadmium, cobalt, chromium, copper, iron, magnesium, manganese, molybdenum, nickel, lead, selenium, thallium, vanadium, and zinc were determined by inductively coupled plasma mass spectroscopy. Adverse health effects due to lead were characterized by assessing blood δ-aminolevulinic acid dehydratase (ALAD) enzyme activity. Adverse effects associated with zinc poisoning were determined from histologic examination of pancreas tissues. Elevated tissue lead concentrations and inhibited blood ALAD enzyme activities were consistently found in birds at all contaminated sites. Histopathologic signs of zinc poisoning, including fibrosis and vacuolization, were associated with elevated pancreatic zinc concentrations at one of the study sites. Adverse health effects associated with other analyzed elements, or tissue concentrations indicating potentially toxic exposure levels to these elements, were not observed.

Regulation of porphyrin synthesis and photodynamic therapy in heavy metal intoxication.

Science.gov (United States)

Grinblat, Borislava; Pour, Nir; Malik, Zvi

2006-01-01

Protoporphyrin IX (PpIX) synthesis by malignant cells is successfully exploited for photodynamic therapy (PDT) following administration of 5-aminolevulinic acid (ALA) and light irradiation. The influence of two environmental heavy metal poisons, lead and gallium, on PpIX-synthesis and ALA-PDT was studied in two neu-ronal cell lines, SH-SY5Y neuroblastoma and PC12 pheochromocytoma. The heavy metal intoxication affected two of the heme-synthesis enzymes, ALA-dehydratase (ALAD) and porphobilinogen deaminase (PBGD). The present results show that lead poisoning significantly decreased the PBGD cellular level and inhibited its enzymatic activity, whereas the effects of gallium were less prominent. Although, the protein levels were reduced, the mRNA levels of PBGD remained unchanged during metal intoxication. These findings show additional inhibitory activity of lead on top of its classical effect on ALAD. Proteasome activity was enhanced during lead treatment, as measured by the AMC fluorigenic proteasome assay. The reduction in PBGD levels was not a consequence of PBGD mRNA reduced synthesis, which remained unchanged as shown by RT-PCR analysis. As a result of the lead poisoning, marked alterations in the cell cycle were observed, including a decreased G1 phase and an increased number of S phase cells. The efficacy of ALA-PDT was reduced in correlation with decreased activities of the enzymes during lead intoxication. We may conclude that lead poisoning adversely affects the outcome of ALA photodynamic therapy of cancer.

Alteration of paraoxonase, arylesterase and lactonase activities in people around fluoride endemic area of Tamil Nadu, India.

Science.gov (United States)

Arulkumar, Mani; Vijayan, Raji; Penislusshiyan, Sakayanathan; Sathishkumar, Palanivel; Angayarkanni, Jayaraman; Palvannan, Thayumanavan

2017-08-01

Toxicity due to excess fluoride concentration in drinking water is of great concern in people who rely only on the ground water as their water source in many region of the world. We collected samples and examined the toxicity of fluoride in a population residing at Salem, Dharmapuri and Krishnagiri districts of Tamil Nadu, India and measured HDL bound enzyme (PON1), erythrocyte membrane bound enzymes (acetylcholinesterase, AChE) and adenosine 5' triphosphatase (ATPases), plasma enzyme (butyrylcholinesterase, BChE) and rate limiting enzyme in heme biosynthesis (delta aminolevulinic acid dehydratase, δ-ALAD) activities. In fluorosis patients, formation of lipid peroxidation product was more in erythrocytes than in plasma. The observation further revealed that there was 50% reduction in the activity of HDL bound anti atherogenic enzyme-paraoxonase (PON1). The activities of membrane bound and signaling enzymes (acetylcholinesterase - AChE and adenosine 5' triphosphatase - ATPase) of erythrocyte were also diminished. These results suggested that there was defectiveness in the signaling and energy metabolism in fluorosis patients. Altered isoenzyme pattern of lactate dehydrogenase (LDH) in fluorosis samples was observed. Furthermore, the result suggested that both the heart (LDH 1) and liver (LDH 5) were most affected by fluoride toxicity. The study also provided reference values for tests which are used to predict the severity of fluoride toxicity. The toxic effect of fluoride was due to the collective effects on vital protective system rather than single factor. Copyright © 2017 Elsevier B.V. All rights reserved.

Swit_4259, an acetoacetate decarboxylase-like enzyme from Sphingomonas wittichii RW1

Energy Technology Data Exchange (ETDEWEB)

Mydy, Lisa S.; Mashhadi, Zahra; Knight, T. William; Fenske, Tyler; Hagemann, Trevor; Hoppe, Robert W.; Han, Lanlan; Miller, Todd R.; Schwabacher, Alan W.; Silvaggi, Nicholas R. (UW); (Vanderbilt)

2017-11-14

The Gram-negative bacteriumSphingomonas wittichiiRW1 is notable for its ability to metabolize a variety of aromatic hydrocarbons. Not surprisingly, theS. wittichiigenome contains a number of putative aromatic hydrocarbon-degrading gene clusters. One of these includes an enzyme of unknown function, Swit_4259, which belongs to the acetoacetate decarboxylase-like superfamily (ADCSF). Here, it is reported that Swit_4259 is a small (28.8 kDa) tetrameric ADCSF enzyme that, unlike the prototypical members of the superfamily, does not have acetoacetate decarboxylase activity. Structural characterization shows that the tertiary structure of Swit_4259 is nearly identical to that of the true decarboxylases, but there are important differences in the fine structure of the Swit_4259 active site that lead to a divergence in function. In addition, it is shown that while it is a poor substrate, Swit_4259 can catalyze the hydration of 2-oxo-hex-3-enedioate to yield 2-oxo-4-hydroxyhexanedioate. It is also demonstrated that Swit_4259 has pyruvate aldolase-dehydratase activity, a feature that is common to all of the family V ADCSF enzymes studied to date. The enzymatic activity, together with the genomic context, suggests that Swit_4259 may be a hydratase with a role in the metabolism of an as-yet-unknown hydrocarbon. These data have implications for engineering bioremediation pathways to degrade specific pollutants, as well as structure–function relationships within the ADCSF in general.

Influence of environmental parameters on production of the acrolein precursor 3-hydroxypropionaldehyde by Lactobacillus reuteri DSMZ 20016 and its accumulation by wine lactobacilli.

Science.gov (United States)

Bauer, Rolene; du Toit, Maret; Kossmann, Jens

2010-01-31

Lactic acid bacteria belonging to the genus Lactobacillus are known to convert glycerol into 3-hydroxypropionaldehyde (3-HPA) during anaerobic glycerol fermentation. Wine quality can be gravely compromised by the accumulation of 3-HPA, due to its spontaneous conversion to acrolein under wine making conditions. Acrolein is not only a dangerous substance for the living cell, but has been implicated in the development of unpleasant bitterness in beverages. This study evaluates the effect of individual environmental parameters on 3-HPA production by Lactobacillus reuteri DSMZ 20016, which only proved possible under conditions that allow accumulation well below the threshold concentration affecting cell viability. 3-HPA production was optimal at pH 6 and in the presence of 300 mM glycerol. Production increased with an increase in cell concentration up to an OD(600) of 50, whereas higher cell concentrations inhibited accumulation. Data presented in this study suggest that 3-HPA plays a role in regulating its own production through quorum sensing. Glycerol dehydratase possessing bacterial strains isolated from South African red wine, L. pentosus and L. brevis, tested positive for 3-HPA accumulation. 3-HPA is normally intracellularly reduced to 1,3-propanediol. This is the first study demonstrating the ability of wine lactobacilli to accumulate 3-HPA in the fermentation media. Recommendations are made on preventing the formation of acrolein and its precursor 3-HPA in wine. Copyright 2009 Elsevier B.V. All rights reserved.

Construction of ivermectin producer by domain swaps of avermectin polyketide synthase in Streptomyces avermitilis.

Science.gov (United States)

Zhang, Xiaolin; Chen, Zhi; Li, Meng; Wen, Ying; Song, Yuan; Li, Jilun

2006-10-01

Ivermectin, 22, 23-dihydroavermectin B1, is commercially important in human, veterinary medicine, and pesticides. It is currently synthesized by chemical reduction of the double bond between C22 and C23 of avermectins B1, which are a mixture of B1a (>80%) and B1b (produced by fermentation of Streptomyces avermitilis. The cost of ivermectin is much higher than that of avermectins B1 owing to the necessity of region-specific hydrogenation at C22-C23 of avermectins B1 with rhodium chloride as the catalyst for producing ivermectin. Here we report that ivermectin can be produced directly by fermentation of recombinant strains constructed through targeted genetic engineering of the avermectin polyketide synthase (PKS) in S. avermitilis Olm73-12, which produces only avermectins B and not avermectins A and oligomycin. The DNA region encoding the dehydratase (DH) and ketoreductase (KR) domains of module 2 from the avermectin PKS in S. avermitilis Olm73-12 was replaced by the DNA fragment encoding the DH, enoylreductase, and KR domains from module 4 of the pikromycin PKS of Streptomyces venezuelae ATCC 15439 using a gene replacement vector pXL211. Twenty-seven of mutants were found to produce a small amount of 22, 23-dihydroavermectin B1a and avermectin B1a and B2a by high performance liquid chromatography and liquid chromatography mass spectrometry analysis. This study might provide a route to the low-cost production of ivermectin by fermentation.

Biomarker responses of Peromyscus leucopus exposed to lead and cadmium in the Southeast Missouri Lead Mining District.

Science.gov (United States)

Beyer, W Nelson; Casteel, Stan W; Friedrichs, Kristen R; Gramlich, Eric; Houseright, Ruth A; Nichols, John R; Karouna-Renier, Natalie K; Kim, Dae Young; Rangen, Kathleen L; Rattner, Barnett A; Schultz, Sandra L

2018-01-29

Biomarker responses and histopathological lesions have been documented in laboratory mammals exposed to elevated concentrations of lead and cadmium. The exposure of white-footed mice (Peromyscus leucopus) to these metals and the potential associated toxic effects were examined at three contaminated sites in the Southeast Missouri Lead Mining District and at a reference site in MO, USA. Mice from the contaminated sites showed evidence of oxidative stress and reduced activity of red blood cell δ-aminolevulinic acid dehydratase (ALAD). Histological examinations of the liver and kidney, cytologic examination of blood smears, and biomarkers of lipid peroxidation and DNA damage failed to show indications of toxic effects from lead. The biomagnification factor of cadmium (hepatic concentration/soil concentration) at a site with a strongly acid soil was 44 times the average of the biomagnification factors at two sites with slightly alkaline soils. The elevated concentrations of cadmium in the mice did not cause observable toxicity, but were associated with about a 50% decrease in expected tissue lead concentrations and greater ALAD activity compared to the activity at the reference site. Lead was associated with a decrease in concentrations of hepatic glutathione and thiols, whereas cadmium was associated with an increase. In addition, to support risk assessment efforts, we developed linear regression models relating both tissue lead dosages (based on a previously published a laboratory study) and tissue lead concentrations in Peromyscus to soil lead concentrations.

The effects of CaEDTA injection on lead, zinc, copper and ALAD in erythrocyte, plasma and urine in lead-exposed workers: a 24-h observation.

Science.gov (United States)

Aono, H; Araki, S

1984-01-01

To evaluate the effects of calcium disodium ethylenediamine tetraacetate (CaEDTA) on the concentrations of lead, zinc and copper in plasma, erythrocyte and urine, and the delta-aminolevulinic acid dehydratase (ALAD) activity in erythrocyte, we administered CaEDTA in 1-h intravenous infusion to ten male gun metal founders with blood-lead concentration of 39 to 64 micrograms/dl (mean 49 micrograms/dl). We found that the plasma concentration of lead, following a rapid rise within the first 3 h, fell temporarily to the level significantly lower than the initial level 19 h after start of the infusion. The plasma concentration of zinc fell to the minimal level 5 h after the infusion; and the erythrocyte concentration of zinc and the ALAD activity concurrently rose to the maximal level 5 h after the infusion. By contrast, no significant alteration was observed in the concentrations of copper in plasma and erythrocyte. The maximal level of urinary metal excretion was attained during the period between 1 and 2 h after start of CaEDTA infusion for lead; within 2 h for zinc; and between 2 and 4 h for copper. The urinary metal excretion returned to the initial level 14 to 24 h after infusion for zinc and copper; but lead excretion was still higher than the initial level during this period. The difference in the kinetics of the three metals following CaEDTA injection is discussed in the light of these findings.

Mobilized plasma lead as an index of lead body burden and its relation to the heme-related indices.

Science.gov (United States)

Sakai, T; Ushio, K; Ikeya, Y

1998-07-01

Plasma lead (Pb-P) from workers were distributed in two main fractions: a protein bound fraction and low molecular weight fractions. Lead mobilized into plasma by CaEDTA was mainly observed in the low molecular weight fraction corresponding to lead disodium ethylenediamine tetraacetic acid (PbEDTA). The peak levels of Pb-P was attained around 1.5 and 2.5 hours after the start of CaEDTA injection. Pb-P and blood lead levels (Pb-B) at 2 h after the injection were 4.26 (+/- 2.84) and 0.96 (+/- 0.27) fold of the initial levels just before the injection. Pb-P concentrations at 2 hours after the start of CaEDTA injection (MPb-P) were well correlated (r = 0.740) with amounts of lead excreted in urine for 24 h thereafter (MPb-U). log MPb-P as well as log MPb-U were correlated with Pb-B (r = 0.765 and 0.817, respectively). Correlation coefficients of lead body burden (MPb-P or MPb-U) vs the logarithms of the effect indices (delta-aminolevulinic acid (ALA) dehydratase, ALA in urine, coproporphyrin in urine, and erythrocyte zinc protoporphyrin) were higher than the correlation coefficients of exposure indices (Pb-B or Pb-U) vs the logarithms of the effect indices. Thus the biological effect monitoring is significant and reliable for evaluating the functional components of lead body burden (MPb-P or MPb-U).

Effects of CaEDTA injection on lead, zinc, copper and ALAD in erythrocyte, plasma and urine in lead-exposed workers: a 24-h observation

Energy Technology Data Exchange (ETDEWEB)

Aono, H.; Araki, S.

1984-01-01

To evaluate the effects of calcium disodium ethylenediamine tetraacetate (CaEDTA) on the concentrations of lead, zinc and copper in plasma, erythrocyte and urine, and the delta-aminolevulinic acid dehydratase (ALAD) activity in erythrocyte, we administered CaEDTA in 1-h intravenous infusion to ten male gun metal founders with blood-lead concentration of 39 to 64 micrograms/dl (mean 49 micrograms/dl). We found that the plasma concentration of lead, following a rapid rise within the first 3 h, fell temporarily to the level significantly lower than the initial level 19 h after start of the infusion. The plasma concentration of zinc fell to the minimal level 5 h after the infusion; and the erythrocyte concentration of zinc and the ALAD activity concurrently rose to the maximal level 5 h after the infusion. By contrast, no significant alteration was observed in the concentrations of copper in plasma and erythrocyte. The maximal level of urinary metal excretion was attained during the period between 1 and 2 h after start of CaEDTA infusion for lead; within 2 h for zinc; and between 2 and 4 h for copper. The urinary metal excretion returned to the initial level 14 to 24 h after infusion for zinc and copper; but lead excretion was still higher than the initial level during this period. The difference in the kinetics of the three metals following CaEDTA injection is discussed in the light of these findings.

Biomarker responses of Peromyscus leucopus exposed to lead and cadmium in the Southeast Missouri Lead Mining District

Science.gov (United States)

Beyer, W. Nelson; Casteel, Stan W.; Friedrichs, Kristen R.; Gramlich, Eric; Houseright, Ruth A.; Nichols, John W.; Karouna-Renier, Natalie; Kim, Dae Young; Rangen, Kathleen; Rattner, Barnett A.; Schultz, Sandra

2018-01-01

Biomarker responses and histopathological lesions have been documented in laboratory mammals exposed to elevated concentrations of lead and cadmium. The exposure of white-footed mice (Peromyscus leucopus) to these metals and the potential associated toxic effects were examined at three contaminated sites in the Southeast Missouri Lead Mining District and at a reference site in MO, USA. Mice from the contaminated sites showed evidence of oxidative stress and reduced activity of red blood cell δ-aminolevulinic acid dehydratase (ALAD). Histological examinations of the liver and kidney, cytologic examination of blood smears, and biomarkers of lipid peroxidation and DNA damage failed to show indications of toxic effects from lead. The biomagnification factor of cadmium (hepatic concentration/soil concentration) at a site with a strongly acid soil was 44 times the average of the biomagnification factors at two sites with slightly alkaline soils. The elevated concentrations of cadmium in the mice did not cause observable toxicity, but were associated with about a 50% decrease in expected tissue lead concentrations and greater ALAD activity compared to the activity at the reference site. Lead was associated with a decrease in concentrations of hepatic glutathione and thiols, whereas cadmium was associated with an increase. In addition, to support risk assessment efforts, we developed linear regression models relating both tissue lead dosages (based on a previously published a laboratory study) and tissue lead concentrations in Peromyscus to soil lead concentrations.

Selection of micronutrients used along with DMSA in the treatment of moderately lead intoxicated mice

Energy Technology Data Exchange (ETDEWEB)

Liao, Yingjun [China Medical University, Department of Physiology, School of Basic Medicine, Shenyang, Liaoning (China); Yu, Fei; Zhi, Xuping; An, Li; Yang, Jun [China Medical University, Department of Nutrition and Food Hygiene, School of Public Health, Shenyang, Liaoning (China); Jin, Yaping; Lu, Chunwei; Li, Gexin [China Medical University, Department of Environmental and Occupational Health, School of Public Health, Shenyang, Liaoning (China)

2008-01-15

The objective of this study was to explore the optimum combination of micronutrients used with 2,3-dimercaptosuccinic acid (DMSA) in the treatment of moderately lead-intoxicated mice. Experiment was carried out based on the orthogonal design L{sub 8}(2{sup 7}) setting six factors with two different levels of each, and eight groups of mice were needed. Mice were exposed to lead by drinking water contaminated with 0.1% lead acetate for four consecutive weeks, and then supplemented by gavage with different combinations of micronutrients with and without DMSA as designed in the orthogonal table. Lead levels in blood, liver, kidney, brain and bone and activities of blood {delta}-aminolevulinic acid dehydratase (ALAD) were analyzed after cessation of supplementation. The results suggested that DMSA was the only factor which could decrease significantly lead levels in blood, liver, kidney and bone; calcium and ascorbic acid were the notable factors decreasing lead levels in blood, liver, kidney, bone and brain; zinc and calcium were the notable factors reversing the lead-inhibited activities of blood ALAD; taurine was the notable factor decreasing lead levels in kidney and brain; and thiamine was the notable factor decreasing lead levels in brain. The lowest lead level in blood, liver, kidney and bone was shown in the mice supplemented with combination of calcium and ascorbic acid along with DMSA. In conclusion, the optimum combination of micronutrients used with DMSA suggested in present study was calcium and ascorbic acid, which seemed to potentiate the chelating efficacy of DMSA in the treatment of moderately lead intoxicated mice. (orig.)

Exposure to Pb, Cd, and As mixtures potentiates the production of oxidative stress precursors: 30-day, 90-day, and 180-day drinking water studies in rats.

Science.gov (United States)

Whittaker, Margaret H; Wang, Gensheng; Chen, Xue-Qing; Lipsky, Michael; Smith, Donald; Gwiazda, Roberto; Fowler, Bruce A

2011-07-15

Exposure to chemical mixtures is a common and important determinant of toxicity and is of particular concern due to their appearance in sources of drinking water. Despite this, few in vivo mixture studies have been conducted to date to understand the health impact of chemical mixtures compared to single chemicals. Interactive effects of lead (Pb), cadmium (Cd) and arsenic (As) were evaluated in 30-, 90-, and 180-day factorial design drinking water studies in rats designed to test the hypothesis that ingestion of such mixtures at individual component Lowest-Observed-Effect-Levels (LOELs) results in increased levels of the pro-oxidant delta aminolevulinic acid (ALA), iron, and copper. LOEL levels of Pb, Cd, and As mixtures resulted in the increased presence of mediators of oxidative stress such as ALA, copper, and iron. ALA increases were followed by statistically significant increases in kidney copper in the 90- and 180-day studies. Statistical evidence of interaction was identified for six biologically relevant variables: blood delta aminolevulinic acid dehydratase (ALAD), kidney ALAD, urinary ALA, urinary iron, kidney iron, and kidney copper. The current investigations underscore the importance of considering interactive effects that common toxic agents such as Pb, Cd, and As may have upon one another at low-dose levels. The interactions between known toxic trace elements at biologically relevant concentrations shown here demonstrate a clear need to rigorously review methods by which national/international agencies assess health risks of chemicals, since exposures may commonly occur as complex mixtures. Copyright © 2011. Published by Elsevier Inc.

Contributions of citrate in redox potential maintenance and ATP production: metabolic pathways and their regulation in Lactobacillus panis PM1.

Science.gov (United States)

Kang, Tae Sun; Korber, Darren R; Tanaka, Takuji

2013-10-01

Lactobacillus panis PM1 belongs to the group III heterofermentative lactobacilli and can utilize various NADH-reoxidizing routes (e.g., citrate, glycerol, and oxygen) according to environmental conditions. In this study, we investigated the ability of L. panis PM1 to produce succinate, acetate, and lactate via citrate utilization. Possible pathways, as well as regulation, for citrate metabolism were examined on the basis of the genome sequence data and metabolic profiles of L. panis PM1. The presence of citrate led to the up-regulation, at the transcriptional level, of the genes encoding for citrate lyase, malate dehydrogenase, and malic enzyme of the citrate pathways by 10- to 120-fold. The transcriptional regulator of the dha operon coding for glycerol dehydratase of L. panis PM1 repressed the expression of the citrate lyase gene (10-fold). Metabolite analyses indicated that the transcriptional enhancement by citrate stimulated succinate yield. Citrate metabolism contributed to energy production by providing a major alternate pathway for NAD(+) regeneration and allowed acetyl phosphate to yield acetate/ATP instead of ethanol/NAD(+). Additionally, a branching pathway from oxaloacetate to pyruvate increased the pool of lactate, which was then used to produce ATP during stationary phase. However, the redirection of NADH-to-citrate utilization resulted in stress caused by end-products (i.e., succinate and acetate). This stress reduced succinate production by up to 50 % but did not cause significant changes at transcriptional level. Overall, citrate utilization was beneficial for the growth of L. panis PM1 by providing a NAD(+) regeneration route and producing extra ATP.

Progressive Structural Defects in Canine Centronuclear Myopathy Indicate a Role for HACD1 in Maintaining Skeletal Muscle Membrane Systems.

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Walmsley, Gemma L; Blot, Stéphane; Venner, Kerrie; Sewry, Caroline; Laporte, Jocelyn; Blondelle, Jordan; Barthélémy, Inès; Maurer, Marie; Blanchard-Gutton, Nicolas; Pilot-Storck, Fanny; Tiret, Laurent; Piercy, Richard J

2017-02-01

Mutations in HACD1/PTPLA cause recessive congenital myopathies in humans and dogs. Hydroxyacyl-coA dehydratases are required for elongation of very long chain fatty acids, and HACD1 has a role in early myogenesis, but the functions of this striated muscle-specific enzyme in more differentiated skeletal muscle remain unknown. Canine HACD1 deficiency is histopathologically classified as a centronuclear myopathy (CNM). We investigated the hypothesis that muscle from HACD1-deficient dogs has membrane abnormalities in common with CNMs with different genetic causes. We found progressive changes in tubuloreticular and sarcolemmal membranes and mislocalized triads and mitochondria in skeletal muscle from animals deficient in HACD1. Furthermore, comparable membranous abnormalities in cultured HACD1-deficient myotubes provide additional evidence that these defects are a primary consequence of altered HACD1 expression. Our novel findings, including T-tubule dilatation and disorganization, associated with defects in this additional CNM-associated gene provide a definitive pathophysiologic link with these disorders, confirm that dogs deficient in HACD1 are relevant models, and strengthen the evidence for a unifying pathogenesis in CNMs via defective membrane trafficking and excitation-contraction coupling in muscle. These results build on previous work by determining further functional roles of HACD1 in muscle and provide new insight into the pathology and pathogenetic mechanisms of HACD1 CNM. Consequently, alterations in membrane properties associated with HACD1 mutations should be investigated in humans with related phenotypes. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Evaluation of toxic metals and essential elements in children with learning disabilities from a rural area of southern Brazil.

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do Nascimento, Sabrina Nunes; Charão, Mariele Feiffer; Moro, Angela Maria; Roehrs, Miguel; Paniz, Clovis; Baierle, Marília; Brucker, Natália; Gioda, Adriana; Barbosa, Fernando; Bohrer, Denise; Ávila, Daiana Silva; Garcia, Solange Cristina

2014-10-17

Children's exposure to metals can result in adverse effects such as cognitive function impairments. This study aimed to evaluate some toxic metals and levels of essential trace elements in blood, hair, and drinking water in children from a rural area of Southern Brazil. Cognitive ability and δ-aminolevulinate dehydratase (ALA-D) activity were evaluated. Oxidative stress was evaluated as a main mechanism of metal toxicity, through the quantification of malondialdehyde (MDA) levels. This study included 20 children from a rural area and 20 children from an urban area. Our findings demonstrated increase in blood lead (Pb) levels (BLLs). Also, increased levels of nickel (Ni) in blood and increase of aluminum (Al) levels in hair and drinking water in rural children were found. Deficiency in selenium (Se) levels was observed in rural children as well. Rural children with visual-motor immaturity presented Pb levels in hair significantly increased in relation to rural children without visual-motor immaturity (p < 0.05). Negative correlations between BLLs and ALA-D activity and positive correlations between BLLs and ALA-RE activity were observed. MDA was significantly higher in rural compared to urban children (p < 0.05). Our findings suggest that rural children were co-exposed to toxic metals, especially Al, Pb and Ni. Moreover, a slight deficiency of Se was observed. Low performance on cognitive ability tests and ALA-D inhibition can be related to metal exposure in rural children. Oxidative stress was suggested as a main toxicological mechanism involved in metal exposure.

Evaluation of Toxic Metals and Essential Elements in Children with Learning Disabilities from a Rural Area of Southern Brazil

Directory of Open Access Journals (Sweden)

Sabrina Nunes do Nascimento

2014-10-01

Full Text Available Children’s exposure to metals can result in adverse effects such as cognitive function impairments. This study aimed to evaluate some toxic metals and levels of essential trace elements in blood, hair, and drinking water in children from a rural area of Southern Brazil. Cognitive ability and δ-aminolevulinate dehydratase (ALA-D activity were evaluated. Oxidative stress was evaluated as a main mechanism of metal toxicity, through the quantification of malondialdehyde (MDA levels. This study included 20 children from a rural area and 20 children from an urban area. Our findings demonstrated increase in blood lead (Pb levels (BLLs. Also, increased levels of nickel (Ni in blood and increase of aluminum (Al levels in hair and drinking water in rural children were found. Deficiency in selenium (Se levels was observed in rural children as well. Rural children with visual-motor immaturity presented Pb levels in hair significantly increased in relation to rural children without visual-motor immaturity (p < 0.05. Negative correlations between BLLs and ALA-D activity and positive correlations between BLLs and ALA-RE activity were observed. MDA was significantly higher in rural compared to urban children (p < 0.05. Our findings suggest that rural children were co-exposed to toxic metals, especially Al, Pb and Ni. Moreover, a slight deficiency of Se was observed. Low performance on cognitive ability tests and ALA-D inhibition can be related to metal exposure in rural children. Oxidative stress was suggested as a main toxicological mechanism involved in metal exposure.

De novo biosynthesis of vanillin in fission yeast (Schizosaccharomyces pombe) and baker's yeast (Saccharomyces cerevisiae).

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Hansen, Esben H; Møller, Birger Lindberg; Kock, Gertrud R; Bünner, Camilla M; Kristensen, Charlotte; Jensen, Ole R; Okkels, Finn T; Olsen, Carl E; Motawia, Mohammed S; Hansen, Jørgen

2009-05-01

Vanillin is one of the world's most important flavor compounds, with a global market of 180 million dollars. Natural vanillin is derived from the cured seed pods of the vanilla orchid (Vanilla planifolia), but most of the world's vanillin is synthesized from petrochemicals or wood pulp lignins. We have established a true de novo biosynthetic pathway for vanillin production from glucose in Schizosaccharomyces pombe, also known as fission yeast or African beer yeast, as well as in baker's yeast, Saccharomyces cerevisiae. Productivities were 65 and 45 mg/liter, after introduction of three and four heterologous genes, respectively. The engineered pathways involve incorporation of 3-dehydroshikimate dehydratase from the dung mold Podospora pauciseta, an aromatic carboxylic acid reductase (ACAR) from a bacterium of the Nocardia genus, and an O-methyltransferase from Homo sapiens. In S. cerevisiae, the ACAR enzyme required activation by phosphopantetheinylation, and this was achieved by coexpression of a Corynebacterium glutamicum phosphopantetheinyl transferase. Prevention of reduction of vanillin to vanillyl alcohol was achieved by knockout of the host alcohol dehydrogenase ADH6. In S. pombe, the biosynthesis was further improved by introduction of an Arabidopsis thaliana family 1 UDP-glycosyltransferase, converting vanillin into vanillin beta-D-glucoside, which is not toxic to the yeast cells and thus may be accumulated in larger amounts. These de novo pathways represent the first examples of one-cell microbial generation of these valuable compounds from glucose. S. pombe yeast has not previously been metabolically engineered to produce any valuable, industrially scalable, white biotech commodity.

De Novo Biosynthesis of Vanillin in Fission Yeast (Schizosaccharomyces pombe) and Baker's Yeast (Saccharomyces cerevisiae) ▿

Science.gov (United States)

Hansen, Esben H.; Møller, Birger Lindberg; Kock, Gertrud R.; Bünner, Camilla M.; Kristensen, Charlotte; Jensen, Ole R.; Okkels, Finn T.; Olsen, Carl E.; Motawia, Mohammed S.; Hansen, Jørgen

2009-01-01

Vanillin is one of the world's most important flavor compounds, with a global market of 180 million dollars. Natural vanillin is derived from the cured seed pods of the vanilla orchid (Vanilla planifolia), but most of the world's vanillin is synthesized from petrochemicals or wood pulp lignins. We have established a true de novo biosynthetic pathway for vanillin production from glucose in Schizosaccharomyces pombe, also known as fission yeast or African beer yeast, as well as in baker's yeast, Saccharomyces cerevisiae. Productivities were 65 and 45 mg/liter, after introduction of three and four heterologous genes, respectively. The engineered pathways involve incorporation of 3-dehydroshikimate dehydratase from the dung mold Podospora pauciseta, an aromatic carboxylic acid reductase (ACAR) from a bacterium of the Nocardia genus, and an O-methyltransferase from Homo sapiens. In S. cerevisiae, the ACAR enzyme required activation by phosphopantetheinylation, and this was achieved by coexpression of a Corynebacterium glutamicum phosphopantetheinyl transferase. Prevention of reduction of vanillin to vanillyl alcohol was achieved by knockout of the host alcohol dehydrogenase ADH6. In S. pombe, the biosynthesis was further improved by introduction of an Arabidopsis thaliana family 1 UDP-glycosyltransferase, converting vanillin into vanillin β-d-glucoside, which is not toxic to the yeast cells and thus may be accumulated in larger amounts. These de novo pathways represent the first examples of one-cell microbial generation of these valuable compounds from glucose. S. pombe yeast has not previously been metabolically engineered to produce any valuable, industrially scalable, white biotech commodity. PMID:19286778

Effects of lead on lactating rats and their sucklings

Energy Technology Data Exchange (ETDEWEB)

Roels, H; Lauwerys, R; Buchet, J P; Hubermont, G

1977-08-01

Lead was administered to lactating rats in drinking water (0, 1, 10, and 100 ppM) from the day of delivery up to day 21 after delivery, at which time the mothers and their newborns were sacrificed. Various parameters of blood: lead concentration (Pb-B), hematocrit (Htc), hemoglobin (Hb), free erythrocyte porphyrin concentration (FEP), delta-aminolevulinate dehydratase activity (ALAD)--and of tissue: ALAD activity, free tissue porphyrin concentration (FTP) and lead concentration (Pb-T) were determined. In mothers, a significant increase of Pb-B and a reduction of ALAD activity of blood were found in the 100 ppM group. In tissues Pb was significantly increased in liver of the 100 ppM group and in kidney of the 10 and 100 ppM groups. None of the biochemical parameters measured in tissues was significantly modified. In suckling rats an increase in Pb-B and a reduction of ALAD activity in blood were found in the 10 and 100 ppM lead groups. Pb concentration was significantly increased in liver, kidney and brain of the 100 ppM group and in kidney of the 10 ppM group. Lead storage in kidney of the 100 ppM group was associated with a marked increase in FTP and a slight reduction in ALAD activity. On the basis of the biochemical parameters studied in the newborn rats, the ''no-effect'' level of lead administered in drinking water during lactation is around 1 ppM, which is rather similar to that found when lead was administered to the mother before and/or during pregnancy.

Eryptosis in lead-exposed workers.

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Aguilar-Dorado, Itzel-Citlalli; Hernández, Gerardo; Quintanar-Escorza, Martha-Angelica; Maldonado-Vega, María; Rosas-Flores, Margarita; Calderón-Salinas, José-Víctor

2014-12-01

Eryptosis is a physiological phenomenon in which old and damaged erythrocytes are removed from circulation. Erythrocytes incubated with lead have exhibited major eryptosis. In the present work we found evidence of high levels of eryptosis in lead exposed workers possibly via oxidation. Blood samples were taken from 40 male workers exposed to lead (mean blood lead concentration 64.8μg/dl) and non-exposed workers (4.2μg/dl). The exposure to lead produced an intoxication characterized by 88.3% less δ-aminolevulinic acid dehydratase (δALAD) activity in lead exposed workers with respect to non-lead exposed workers. An increment of oxidation in lead exposed workers was characterized by 2.4 times higher thiobarbituric acid-reactive substance (TBARS) concentration and 32.8% lower reduced/oxidized glutathione (GSH/GSSG) ratio. Oxidative stress in erythrocytes of lead exposed workers is expressed in 192% higher free calcium concentration [Ca(2+)]i and 1.6 times higher μ-calpain activity with respect to non-lead exposed workers. The adenosine triphosphate (ATP) concentration was not significantly different between the two worker groups. No externalization of phosphatidylserine (PS) was found in non-lead exposed workers (lead exposed workers showed 2.82% externalization. Lead intoxication induces eryptosis possibly through a molecular pathway that includes oxidation, depletion of reduced glutathione (GSH), increment of [Ca(2+)], μ-calpain activation and externalization of PS in erythrocytes. Identifying molecular signals that induce eryptosis in lead intoxication is necessary to understand its physiopathology and chronic complications. Copyright © 2014 Elsevier Inc. All rights reserved.

Behavior of active deposit of lead (Teisinger) in the Japanese free from occupational exposure to lead

Energy Technology Data Exchange (ETDEWEB)

Araki, S

1973-12-01

Intravenous infusion of calcium disodium ethylenediamine tetraacetate (CaEDTA) was given to 45 Japanese adults without occupational exposure to lead for 1 hr at a dosage of 20 mg/kg body weight in 250 ml of 5 percent glucose solution. The urinary excretion of lead was estimated for 24 hr before, and for 2 hr and 24 hr after the administration. The least variation of the lead content was recognized in the 24-hour urinary excretion after the injection of CaEDTA. No sexual difference was noted in the creatinine-corrected lead concentration. By multiple linear regression and correlation analyses, age was found to be significant in determining positively the lead level mobilized in 24-hour urine samples. Height was significant in determining positively the spontaneous 24-hour urinary lead excretion. Certain significant correlations existed among lead in blood, delta-aminolevulinic acid dehydratase in erythrocytes, delta-aminolevulinic acid in urine, coproporphyrin in urine, lead in urine, and lead mobilized by CaEDTA. The existence of active body burden of lead was suggested in human subjects under usual urban conditions where the total ambient lead concentration averaged 1.7 micrograms/cm m of air. Based on a few assumptions, it was calculated that about 3 micrograms of lead was retained on the average per day by a Japanese adult. Daily retention of lead by Japanese adults was formularized as lead in micrograms equals a constant (K) times daily creatinine excretion in grams, where K is 1.77 in men and 2.73 in women. (Air Pollut. Abstr.)

Structural and Biochemical Investigation of PglF from Campylobacter jejuni Reveals a New Mechanism for a Member of the Short Chain Dehydrogenase/Reductase Superfamily

Energy Technology Data Exchange (ETDEWEB)

Riegert, Alexander S. [Department; Thoden, James B. [Department; Schoenhofen, Ian C. [National; Watson, David C. [National; Young, N. Martin [National; Tipton, Peter A. [Department; Holden, Hazel M. [Department

2017-11-03

Within recent years it has become apparent that protein glycosylation is not limited to eukaryotes. Indeed, in Campylobacter jejuni, a Gram-negative bacterium, more than 60 of its proteins are known to be glycosylated. One of the sugars found in such glycosylated proteins is 2,4-diacetamido-2,4,6-trideoxy-α-d-glucopyranose, hereafter referred to as QuiNAc4NAc. The pathway for its biosynthesis, initiating with UDP-GlcNAc, requires three enzymes referred to as PglF, PglE, and PlgD. The focus of this investigation is on PglF, an NAD+-dependent sugar 4,6-dehydratase known to belong to the short chain dehydrogenase/reductase (SDR) superfamily. Specifically, PglF catalyzes the first step in the pathway, namely, the dehydration of UDP-GlcNAc to UDP-2-acetamido-2,6-dideoxy-α-d-xylo-hexos-4-ulose. Most members of the SDR superfamily contain a characteristic signature sequence of YXXXK where the conserved tyrosine functions as a catalytic acid or a base. Strikingly, in PglF, this residue is a methionine. Here we describe a detailed structural and functional investigation of PglF from C. jejuni. For this investigation five X-ray structures were determined to resolutions of 2.0 Å or better. In addition, kinetic analyses of the wild-type and site-directed variants were performed. On the basis of the data reported herein, a new catalytic mechanism for a SDR superfamily member is proposed that does not require the typically conserved tyrosine residue.

Biochemical characterization of GDP-L-fucose de novo synthesis pathway in fungus Mortierella alpina

International Nuclear Information System (INIS)

Ren, Yan; Perepelov, Andrei V.; Wang, Haiyan; Zhang, Hao; Knirel, Yuriy A.; Wang, Lei; Chen, Wei

2010-01-01

Mortierella alpina is a filamentous fungus commonly found in soil, which is able to produce large amount of polyunsaturated fatty acids. L-Fucose is an important sugar found in a diverse range of organisms, playing a variety of biological roles. In this study, we characterized the de novo biosynthetic pathway of GDP-L-fucose (the nucleotide-activated form of L-fucose) in M. alpina. Genes encoding GDP-D-mannose 4,6-dehydratase (GMD) and GDP-keto-6-deoxymannose 3,5-epimerase/4-reductase (GMER) were expressed heterologously in Escherichia coli. The recombinant enzymes were produced as His-tagged fusion proteins. Conversion of GDP-mannose to GDP-4-keto-6-deoxy mannose by GMD and GDP-4-keto-6-deoxy mannose to GDP-L-fucose by GMER were analyzed by capillary electrophoresis, electro-spray ionization-mass spectrometry, and nuclear magnetic resonance spectroscopy. The k m values of GMD for GDP-mannose and GMER for GDP-4-keto-6-deoxy mannose were determined to be 0.77 mM and 1.047 mM, respectively. Both NADH and NADPH may be used by GMER as the coenzyme. The optimum temperature and pH were determined to be 37 o C and pH 9.0 (GMD) or pH 7.0 (GMER). Divalent cations are not required for GMD and GMER activity, and the activities of both enzymes may be enhanced by DTT. To our knowledge this is the first report on the characterization of GDP-L-fucose biosynthetic pathway in fungi.

Effects of lead in nestling black-crowned night-herons (Nycticorax nycticorax) experimentally dosed in the field

Science.gov (United States)

Golden, N.H.; Rattner, B.A.; Cohen, J.B.; Hoffman, D.J.; Ottinger, M.A.

2000-01-01

Lead is a known environmental toxicant, and poisoning resulting from the ingestion of lead shot has been well-documented in many species of waterfowl. However, much less is known regarding exposure and effects of free environmental lead in species of birds other than waterfowl. In an attempt to evaluate toxicity of lead to herons and to determine the usefulness of feathers as a non-invasive exposure-monitoring tool, black-crowned night-heron nestlings were dosed with lead to determine its distribution among tissues, and its effects on biochemical biomarkers, growth, and survival. Five-day-old heron nestlings (one per nest) at Chincoteague Bay, Virginia were given a single intra-peritoneal injection of dosing vehicle (control; N=7) or one of three lead solutions (as lead nitrate) (10, 50, or 250 mg/kg body weight of nestling; N=7 per dose) chosen to represent levels below, at, and above those found in moderately-polluted environments. All nestlings treated with lead exhibited dose-dependent inhibition of delta-aminolevulinic acid dehydratase (ALAD) activity compared to controls, and nestlings treated with the highest concentration showed a reduced carcass weight compared to controls. Of several measures of oxidative stress that were analyzed, significant differences were found between low- and high-dosed nestlings in hepatic total thiol and protein-bound sulfhydryl concentrations. No differences in survival were detected between dosed nestlings, controls, or uninjected siblings. Lead concentrations in several matrices, including feathers, are being determined to assess distribution among tissues and will also be examined for relationships with measures of effect.

Effects of chlorogenic acid, caffeine, and coffee on behavioral and biochemical parameters of diabetic rats.

Science.gov (United States)

Stefanello, Naiara; Schmatz, Roberta; Pereira, Luciane Belmonte; Rubin, Maribel A; da Rocha, João Batista Teixeira; Facco, Graziela; Pereira, Maria Ester; Mazzanti, Cinthia Melazzo de Andrade; Passamonti, Sabina; Rodrigues, Marília Valvassori; Carvalho, Fabiano Barbosa; da Rosa, Michelle Melgarejo; Gutierres, Jessie Martins; Cardoso, Andréia Machado; Morsch, Vera Maria; Schetinger, Maria Rosa Chitolina

2014-03-01

Diabetes mellitus (DM) is associated with brain alterations that may contribute to cognitive dysfunctions. Chlorogenic acid (CGA) and caffeine (CA), abundant in coffee (CF), are natural compounds that have showed important actions in the brain. The present study aimed to evaluate the effect of CGA, CA, and CF on acetylcholinesterase (AChE), Na(+), K(+)-ATPase, aminolevulinate dehydratase (δ-ALA-D) activities and TBARS levels from cerebral cortex, as well as memory and anxiety in streptozotocin-induced diabetic rats. Animals were divided into eight groups (n = 5-10): control; control/CGA 5 mg/kg; control/CA 15 mg/kg; control/CF 0.5 g/kg; diabetic; diabetic/CGA 5 mg/kg; diabetic/CA 15 mg/kg; and diabetic/CF 0.5 g/kg. Our results demonstrated an increase in AChE activity and TBARS levels in cerebral cortex, while δ-ALA-D and Na(+), K(+)-ATPase activities were decreased in the diabetic rats when compared to control water group. Furthermore, a memory deficit and an increase in anxiety in diabetic rats were observed. The treatment with CGA and CA prevented the increase in AChE activity in diabetic rats when compared to the diabetic water group. CGA, CA, and CF intake partially prevented cerebral δ-ALA-D and Na(+), K(+)-ATPase activity decrease due to diabetes. Moreover, CGA prevented diabetes-induced TBARS production, improved memory, and decreased anxiety. In conclusion, among the compounds studied CGA proved to be a compound which acts better in the prevention of brain disorders promoted by DM.

2,3-Dihydro-2,5-dihydroxy-4H-benzopyran-4-one: a nonphysiological substrate for fungal melanin biosynthetic enzymes.

Science.gov (United States)

Thompson, J E; Basarab, G S; Pierce, J; Hodge, C N; Jordan, D B

1998-02-01

We have synthesized an alternate substrate for trihydroxynaphthalene reductase (3HNR) and scytalone dehydratase (SD), two enzymes in the fungal melanin biosynthetic pathway. The oxidation of 2,3-dihydro-2,5-dihydroxy-4H-benzopyran-4-one (DDBO) to 4,5-dihydroxy-2H-benzopyran-2-one (DBO) with concomitant reduction of NADP+ is catalyzed by 3HNR. DDBO is dehydrated by SD to 5-hydroxy-4H-1-benzopyran-4-one (HBO). These reactions can be monitored using continuous spectrophotometric assays. DDBO race-mizes rapidly, so chiral synthesis to mimic the natural substrate is not required. DDBO, DBO, and HBO are stable in aerated aqueous solution, in contrast to the rapidly autooxidizing trihydroxynaphthalene, a physiological substrate for 3HNR and product of SD. Unlike the natural substrates, DDBO, DBO, and HBO do not change protonation state between pH's 4 and 9. Oxidation of DDBO is effectively irreversible at pH 7, as DBO deprotonates with a pKa of 2.5. At pH 7.0 and 25 degrees C, the kcat for 3HNR catalyzed DDBO oxidation is 14 s-1 and the K(m) is 5 microM; the kcat for SD catalyzed DDBO dehydration is 400 s-1 and the K(m) is 15 microM. Based on these kinetic constants, DDBO is a better substrate than the natural substrate scytalone for both 3HNR and SD at neutral pH. An explanation for the preference of DDBO over scytalone in the oxidation and dehydration reactions is offered.

Endogenous superoxide is a key effector of the oxygen sensitivity of a model obligate anaerobe.

Science.gov (United States)

Lu, Zheng; Sethu, Ramakrishnan; Imlay, James A

2018-04-03

It has been unclear whether superoxide and/or hydrogen peroxide play important roles in the phenomenon of obligate anaerobiosis. This question was explored using Bacteroides thetaiotaomicron , a major fermentative bacterium in the human gastrointestinal tract. Aeration inactivated two enzyme families-[4Fe-4S] dehydratases and nonredox mononuclear iron enzymes-whose homologs, in contrast, remain active in aerobic Escherichia coli Inactivation-rate measurements of one such enzyme, B. thetaiotaomicron fumarase, showed that it is no more intrinsically sensitive to oxidants than is an E. coli fumarase. Indeed, when the E. coli enzymes were expressed in B. thetaiotaomicron , they no longer could tolerate aeration; conversely, the B. thetaiotaomicron enzymes maintained full activity when expressed in aerobic E. coli Thus, the aerobic inactivation of the B. thetaiotaomicron enzymes is a feature of their intracellular environment rather than of the enzymes themselves. B. thetaiotaomicron possesses superoxide dismutase and peroxidases, and it can repair damaged enzymes. However, measurements confirmed that the rate of reactive oxygen species production inside aerated B. thetaiotaomicron is far higher than in E. coli Analysis of the damaged enzymes recovered from aerated B. thetaiotaomicron suggested that they had been inactivated by superoxide rather than by hydrogen peroxide. Accordingly, overproduction of superoxide dismutase substantially protected the enzymes from aeration. We conclude that when this anaerobe encounters oxygen, its internal superoxide levels rise high enough to inactivate key catabolic and biosynthetic enzymes. Superoxide thus comprises a major element of the oxygen sensitivity of this anaerobe. The extent to which molecular oxygen exerts additional direct effects remains to be determined.

Phenylpyruvate Contributes to the Synthesis of Fragrant Benzenoid–Phenylpropanoids in Petunia × hybrida Flowers

Directory of Open Access Journals (Sweden)

Moran Oliva

2017-05-01

Full Text Available Phenylalanine (Phe is a precursor for a large group of plant specialized metabolites, including the fragrant volatile benzenoid–phenylpropanoids (BPs. In plants, the main pathway leading to production of Phe is via arogenate, while the pathway via phenylpyruvate (PPY is considered merely an alternative route. Unlike plants, in most microorganisms the only pathway leading to the synthesis of Phe is via PPY. Here we studied the effect of increased PPY production in petunia on the formation of BPs volatiles and other specialized metabolites originating from Phe both in flowers and leaves. Stimulation of the pathway via PPY was achieved by transforming petunia with PheA∗, a gene encoding a bacterial feedback insensitive bi-functional chorismate mutase/prephenate dehydratase enzyme. PheA∗ overexpression caused dramatic increase in the levels of flower BP volatiles such as phenylacetaldehyde, benzaldehyde, benzyl acetate, vanillin, and eugenol. All three BP pathways characterized in petunia flowers were stimulated in PheA∗ flowers. In contrast, PheA∗ overexpression had only a minor effect on the levels of amino acids and non-volatile metabolites both in the leaves and flowers. The one exception is a dramatic increase in the level of rosmarinate, a conjugate between Phe-derived caffeate and Tyr-derived 3,4-dihydroxyphenylacetate, in PheA∗ leaves. PheA∗ petunia flowers may serve as an excellent system for revealing the role of PPY in the production of BPs, including possible routes directly converting PPY to the fragrant volatiles. This study emphasizes the potential of the PPY route in achieving fragrance enhancement in flowering plants.

Haloperidol-loaded lipid-core polymeric nanocapsules reduce DNA damage in blood and oxidative stress in liver and kidneys of rats

International Nuclear Information System (INIS)

Roversi, Katiane; Benvegnú, Dalila M.; Roversi, Karine; Trevizol, Fabíola; Vey, Luciana T.; Elias, Fabiana; Fracasso, Rafael

2015-01-01

Haloperidol (HP) nanoencapsulation improves therapeutic efficacy, prolongs the drug action time, and reduces its motor side effects. However, in a view of HP toxicity in organs like liver and kidneys in addition to the lack of knowledge regarding the toxicity of polymeric nanocapsules, our aim was to verify the influence of HP-nanoformulation on toxicity and oxidative stress markers in the liver and kidneys of rats, also observing the damage caused in the blood. For such, 28 adult male Wistar rats were designated in four experimental groups (n = 7) and treated with vehicle (C group), free haloperidol suspension (FH group), blank nanocapsules suspension (B-Nc group), and haloperidol-loaded lipid-core nanocapsules suspension (H-Nc group). The nanocapsules formulation presented the size of approximately 250 nm. All suspensions were administered to the animals (0.5 mg/kg/day-i.p.) for a period of 28 days. Our results showed that FH caused damage in the liver, evidenced by increased lipid peroxidation, plasma levels of aspartate aminotransferase, and alanine aminotransferase, as well as decreased cellular integrity and vitamin C levels. In kidneys, FH treatment caused damage to a lesser extent, observed by decreased activity of δ-aminolevulinate dehydratase (ALA-D) and levels of VIT C. In addition, FH treatment was also related to a higher DNA damage index in blood. On the other hand, animals treated with H-Nc and B-Nc did not show damage in liver, kidneys, and DNA. Our study indicates that the nanoencapsulation of haloperidol was able to prevent the sub-chronic toxicity commonly observed in liver, kidneys, and DNA, thus reflecting a pharmacological superiority in relation to free drug

Haloperidol-loaded lipid-core polymeric nanocapsules reduce DNA damage in blood and oxidative stress in liver and kidneys of rats

Science.gov (United States)

Roversi, Katiane; Benvegnú, Dalila M.; Roversi, Karine; Trevizol, Fabíola; Vey, Luciana T.; Elias, Fabiana; Fracasso, Rafael; Motta, Mariana H.; Ribeiro, Roseane F.; dos S. Hausen, Bruna; Moresco, Rafael N.; Garcia, Solange C.; da Silva, Cristiane B.; Burger, Marilise E.

2015-04-01

Haloperidol (HP) nanoencapsulation improves therapeutic efficacy, prolongs the drug action time, and reduces its motor side effects. However, in a view of HP toxicity in organs like liver and kidneys in addition to the lack of knowledge regarding the toxicity of polymeric nanocapsules, our aim was to verify the influence of HP-nanoformulation on toxicity and oxidative stress markers in the liver and kidneys of rats, also observing the damage caused in the blood. For such, 28 adult male Wistar rats were designated in four experimental groups ( n = 7) and treated with vehicle (C group), free haloperidol suspension (FH group), blank nanocapsules suspension (B-Nc group), and haloperidol-loaded lipid-core nanocapsules suspension (H-Nc group). The nanocapsules formulation presented the size of approximately 250 nm. All suspensions were administered to the animals (0.5 mg/kg/day-i.p.) for a period of 28 days. Our results showed that FH caused damage in the liver, evidenced by increased lipid peroxidation, plasma levels of aspartate aminotransferase, and alanine aminotransferase, as well as decreased cellular integrity and vitamin C levels. In kidneys, FH treatment caused damage to a lesser extent, observed by decreased activity of δ-aminolevulinate dehydratase (ALA-D) and levels of VIT C. In addition, FH treatment was also related to a higher DNA damage index in blood. On the other hand, animals treated with H-Nc and B-Nc did not show damage in liver, kidneys, and DNA. Our study indicates that the nanoencapsulation of haloperidol was able to prevent the sub-chronic toxicity commonly observed in liver, kidneys, and DNA, thus reflecting a pharmacological superiority in relation to free drug.

Environmental adaptability and stress tolerance of Laribacter hongkongensis: a genome-wide analysis

Directory of Open Access Journals (Sweden)

Lau Susanna KP

2011-06-01

Full Text Available Abstract Background Laribacter hongkongensis is associated with community-acquired gastroenteritis and traveler's diarrhea and it can reside in human, fish, frogs and water. In this study, we performed an in-depth annotation of the genes in its genome related to adaptation to the various environmental niches. Results L. hongkongensis possessed genes for DNA repair and recombination, basal transcription, alternative σ-factors and 109 putative transcription factors, allowing DNA repair and global changes in gene expression in response to different environmental stresses. For acid stress, it possessed a urease gene cassette and two arc gene clusters. For alkaline stress, it possessed six CDSs for transporters of the monovalent cation/proton antiporter-2 and NhaC Na+:H+ antiporter families. For heavy metals acquisition and tolerance, it possessed CDSs for iron and nickel transport and efflux pumps for other metals. For temperature stress, it possessed genes related to chaperones and chaperonins, heat shock proteins and cold shock proteins. For osmotic stress, 25 CDSs were observed, mostly related to regulators for potassium ion, proline and glutamate transport. For oxidative and UV light stress, genes for oxidant-resistant dehydratase, superoxide scavenging, hydrogen peroxide scavenging, exclusion and export of redox-cycling antibiotics, redox balancing, DNA repair, reduction of disulfide bonds, limitation of iron availability and reduction of iron-sulfur clusters are present. For starvation, it possessed phosphorus and, despite being asaccharolytic, carbon starvation-related CDSs. Conclusions The L. hongkongensis genome possessed a high variety of genes for adaptation to acid, alkaline, temperature, osmotic, oxidative, UV light and starvation stresses and acquisition of and tolerance to heavy metals.

Excessive by-product formation: A key contributor to low isobutanol yields of engineered Saccharomyces cerevisiae strains.

Science.gov (United States)

Milne, N; Wahl, S A; van Maris, A J A; Pronk, J T; Daran, J M

2016-12-01

It is theoretically possible to engineer Saccharomyces cerevisiae strains in which isobutanol is the predominant catabolic product and high-yielding isobutanol-producing strains are already reported by industry. Conversely, isobutanol yields of engineered S. cerevisiae strains reported in the scientific literature typically remain far below 10% of the theoretical maximum. This study explores possible reasons for these suboptimal yields by a mass-balancing approach. A cytosolically located, cofactor-balanced isobutanol pathway, consisting of a mosaic of bacterial enzymes whose in vivo functionality was confirmed by complementation of null mutations in branched-chain amino acid metabolism, was expressed in S. cerevisiae . Product formation by the engineered strain was analysed in shake flasks and bioreactors. In aerobic cultures, the pathway intermediate isobutyraldehyde was oxidized to isobutyrate rather than reduced to isobutanol. Moreover, significant concentrations of the pathway intermediates 2,3-dihydroxyisovalerate and α-ketoisovalerate, as well as diacetyl and acetoin, accumulated extracellularly. While the engineered strain could not grow anaerobically, micro-aerobic cultivation resulted in isobutanol formation at a yield of 0.018±0.003 mol/mol glucose. Simultaneously, 2,3-butanediol was produced at a yield of 0.649±0.067 mol/mol glucose. These results identify massive accumulation of pathway intermediates, as well as overflow metabolites derived from acetolactate, as an important, previously underestimated contributor to the suboptimal yields of 'academic' isobutanol strains. The observed patterns of by-product formation is consistent with the notion that in vivo activity of the iron-sulphur-cluster-requiring enzyme dihydroxyacid dehydratase is a key bottleneck in the present and previously described 'academic' isobutanol-producing yeast strains.

Thioredoxin and NADPH-Dependent Thioredoxin Reductase C Regulation of Tetrapyrrole Biosynthesis.

Science.gov (United States)

Da, Qingen; Wang, Peng; Wang, Menglong; Sun, Ting; Jin, Honglei; Liu, Bing; Wang, Jinfa; Grimm, Bernhard; Wang, Hong-Bin

2017-10-01

In chloroplasts, thioredoxin (TRX) isoforms and NADPH-dependent thioredoxin reductase C (NTRC) act as redox regulatory factors involved in multiple plastid biogenesis and metabolic processes. To date, less is known about the functional coordination between TRXs and NTRC in chlorophyll biosynthesis. In this study, we aimed to explore the potential functions of TRX m and NTRC in the regulation of the tetrapyrrole biosynthesis (TBS) pathway. Silencing of three genes, TRX m1 , TRX m2 , and TRX m4 ( TRX ms ), led to pale-green leaves, a significantly reduced 5-aminolevulinic acid (ALA)-synthesizing capacity, and reduced accumulation of chlorophyll and its metabolic intermediates in Arabidopsis ( Arabidopsis thaliana ). The contents of ALA dehydratase, protoporphyrinogen IX oxidase, the I subunit of Mg-chelatase, Mg-protoporphyrin IX methyltransferase (CHLM), and NADPH-protochlorophyllide oxidoreductase were decreased in triple TRX m- silenced seedlings compared with the wild type, although the transcript levels of the corresponding genes were not altered significantly. Protein-protein interaction analyses revealed a physical interaction between the TRX m isoforms and CHLM. 4-Acetoamido-4-maleimidylstilbene-2,2-disulfonate labeling showed the regulatory impact of TRX ms on the CHLM redox status. Since CHLM also is regulated by NTRC (Richter et al., 2013), we assessed the concurrent functions of TRX m and NTRC in the control of CHLM. Combined deficiencies of three TRX m isoforms and NTRC led to a cumulative decrease in leaf pigmentation, TBS intermediate contents, ALA synthesis rate, and CHLM activity. We discuss the coordinated roles of TRX m and NTRC in the redox control of CHLM stability with its corollary activity in the TBS pathway. © 2017 American Society of Plant Biologists. All Rights Reserved.

Using biochemical and isotope geochemistry to understand the environmental and public health implications of lead pollution in the lower Guadiana River, Iberia: A freshwater bivalve study

Energy Technology Data Exchange (ETDEWEB)

Company, R. [CIMA, Faculty of Marine and Environmental Sciences, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)], E-mail: rcompany@ualg.pt; Serafim, A.; Lopes, B.; Cravo, A. [CIMA, Faculty of Marine and Environmental Sciences, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Shepherd, T.J.; Pearson, G. [Department of Earth Sciences, Durham University, Science Labs., Durham DH1 3LE (United Kingdom); Bebianno, M.J. [CIMA, Faculty of Marine and Environmental Sciences, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)], E-mail: mbebian@ualg.pt

2008-11-01

Lead is a natural component of aquatic ecosystems with no known biological role and is highly toxic. Its toxicity stems from its ability to mimic biologically important metals and to produce membrane damage through lipid peroxidation (LPO). Most lead poisoning symptoms are thought to occur by interfering with an essential enzyme, {delta}-aminolevulinic acid dehydratase (ALAD), the activity of which is markedly inhibited by lead. The purpose of this work was to study the levels and effects of lead pollution (responses of ALAD and oxidative stress biomarker LPO) in the freshwater bivalve Corbicula fluminea along the lower Guadiana River (Portugal and Spain); a major river system impacted by historic mining pollution and more recent anthropogenic inputs. The results show that the enzymatic activity of ALAD is negatively correlated with the total Pb concentration of the whole tissue suggesting that ALAD has considerable potential as a biomarker of lead exposure in C. fluminea. To identify the sources of lead to which bivalves have been exposed, high precision {sup 206}Pb/{sup 204}Pb, {sup 207}Pb/{sup 204}Pb, {sup 208}Pb/{sup 204}/Pb ratios for C. fluminea confirm that historical mining activities in the Iberian Pyrite Belt are the dominant source of lead pollution in the lower Guadiana River. The isotope patterns however exhibit marked seasonal and geographic variation in response to rainfall and river water management. Locally, other anthropogenic sources of lead have been detected in C. fluminea close to population centres, thus adding to its versatility as a freshwater bio-indicator. Overall, the study highlights the value of natural ecosystems as monitors of water quality and their importance for public health assessment and surveillance.

Contribution of crenarchaeal autotrophic ammonia oxidizers to the dark primary production in Tyrrhenian deep waters (Central Mediterranean Sea).

Science.gov (United States)

Yakimov, Michail M; Cono, Violetta La; Smedile, Francesco; DeLuca, Thomas H; Juárez, Silvia; Ciordia, Sergio; Fernández, Marisol; Albar, Juan Pablo; Ferrer, Manuel; Golyshin, Peter N; Giuliano, Laura

2011-06-01

Mesophilic Crenarchaeota have recently been thought to be significant contributors to nitrogen (N) and carbon (C) cycling. In this study, we examined the vertical distribution of ammonia-oxidizing Crenarchaeota at offshore site in Southern Tyrrhenian Sea. The median value of the crenachaeal cell to amoA gene ratio was close to one suggesting that virtually all deep-sea Crenarchaeota possess the capacity to oxidize ammonia. Crenarchaea-specific genes, nirK and ureC, for nitrite reductase and urease were identified and their affiliation demonstrated the presence of 'deep-sea' clades distinct from 'shallow' representatives. Measured deep-sea dark CO(2) fixation estimates were comparable to the median value of photosynthetic biomass production calculated for this area of Tyrrhenian Sea, pointing to the significance of this process in the C cycle of aphotic marine ecosystems. To elucidate the pivotal organisms in this process, we targeted known marine crenarchaeal autotrophy-related genes, coding for acetyl-CoA carboxylase (accA) and 4-hydroxybutyryl-CoA dehydratase (4-hbd). As in case of nirK and ureC, these genes are grouped with deep-sea sequences being distantly related to those retrieved from the epipelagic zone. To pair the molecular data with specific functional attributes we performed [(14)C]HCO(3) incorporation experiments followed by analyses of radiolabeled proteins using shotgun proteomics approach. More than 100 oligopeptides were attributed to 40 marine crenarchaeal-specific proteins that are involved in 10 different metabolic processes, including autotrophy. Obtained results provided a clear proof of chemolithoautotrophic physiology of bathypelagic crenarchaeota and indicated that this numerically predominant group of microorganisms facilitate a hitherto unrecognized sink for inorganic C of a global importance.

Low blood lead levels impair intellectual and hematological function in children from Cartagena, Caribbean coast of Colombia.

Science.gov (United States)

Alvarez-Ortega, Neda; Caballero-Gallardo, Karina; Olivero-Verbel, Jesus

2017-12-01

Lead produces numerous biochemical and physiological changes in humans, including hematological disorders, toxic effects on the central nervous system and in the function of several organs. The aim of this study was to determine blood lead levels (BLL) in children from Cartagena, Colombia, associating those with hematological and liver damage markers, the intelligence quotient (IQ), as well as with gene expression of the aminolevulinate dehydratase (ALAD), superoxide dismutase 1 (SOD1), gamma interferon (INF-γ), tumor necrosis factor (TNF) and tumor protein (p53). To achieve this purpose, 118 blood samples were collected from children 5-16 years old, with their respective informed consent from their parents. BLL was measured by atomic absorption; hematological parameters were obtained with automated systems; plasma was utilized to analyze hepatic toxicity markers, alanine aminotransferase (ALT), gamma-glutamyltransferase (γ-GT) and alkaline phosphatase (ALP); the Kaufman Brief Intelligence Test (K-BIT) was administered to measure the IQ; and gene expression was quantified from blood RNA. The mean BLL was 1.7±0.3μg/dL. A low proportion of the children (3.4%) had BLL above the CDC recommended limit (5μg/dL). BLL were correlated weakly, but negatively with child age, weight, height, body mass index, platelets wide distribution, mean platelet volume, γ-GT and IQ. There were not significant changes in the expression of evaluated genes. These results support the hypothesis that BLL below 5μg/dL may still be a detrimental factor on children's cognitive abilities, development and hematology, in line with recent concerns that there is no safe level of pediatric lead exposure. Copyright © 2017 Elsevier GmbH. All rights reserved.

Elucidating the structural basis for differing enzyme inhibitor potency by cryo-EM.

Science.gov (United States)

Rawson, Shaun; Bisson, Claudine; Hurdiss, Daniel L; Fazal, Asif; McPhillie, Martin J; Sedelnikova, Svetlana E; Baker, Patrick J; Rice, David W; Muench, Stephen P

2018-02-20

Histidine biosynthesis is an essential process in plants and microorganisms, making it an attractive target for the development of herbicides and antibacterial agents. Imidazoleglycerol-phosphate dehydratase (IGPD), a key enzyme within this pathway, has been biochemically characterized in both Saccharomyces cerevisiae ( Sc_ IGPD) and Arabidopsis thaliana ( At_ IGPD). The plant enzyme, having been the focus of in-depth structural analysis as part of an inhibitor development program, has revealed details about the reaction mechanism of IGPD, whereas the yeast enzyme has proven intractable to crystallography studies. The structure-activity relationship of potent triazole-phosphonate inhibitors of IGPD has been determined in both homologs, revealing that the lead inhibitor (C348) is an order of magnitude more potent against Sc_ IGPD than At_ IGPD; however, the molecular basis of this difference has not been established. Here we have used single-particle electron microscopy (EM) to study structural differences between the At and Sc_ IGPD homologs, which could influence the difference in inhibitor potency. The resulting EM maps at ∼3 Å are sufficient to de novo build the protein structure and identify the inhibitor binding site, which has been validated against the crystal structure of the At_ IGPD/C348 complex. The structure of Sc _IGPD reveals that a 24-amino acid insertion forms an extended loop region on the enzyme surface that lies adjacent to the active site, forming interactions with the substrate/inhibitor binding loop that may influence inhibitor potency. Overall, this study provides insights into the IGPD family and demonstrates the power of using an EM approach to study inhibitor binding. Copyright © 2018 the Author(s). Published by PNAS.

Associations of iron metabolism genes with blood manganese levels: a population-based study with validation data from animal models

Directory of Open Access Journals (Sweden)

Claus Henn Birgit

2011-11-01

Full Text Available Abstract Background Given mounting evidence for adverse effects from excess manganese exposure, it is critical to understand host factors, such as genetics, that affect manganese metabolism. Methods Archived blood samples, collected from 332 Mexican women at delivery, were analyzed for manganese. We evaluated associations of manganese with functional variants in three candidate iron metabolism genes: HFE [hemochromatosis], TF [transferrin], and ALAD [δ-aminolevulinic acid dehydratase]. We used a knockout mouse model to parallel our significant results as a novel method of validating the observed associations between genotype and blood manganese in our epidemiologic data. Results Percentage of participants carrying at least one copy of HFE C282Y, HFE H63D, TF P570S, and ALAD K59N variant alleles was 2.4%, 17.7%, 20.1%, and 6.4%, respectively. Percentage carrying at least one copy of either C282Y or H63D allele in HFE gene was 19.6%. Geometric mean (geometric standard deviation manganese concentrations were 17.0 (1.5 μg/l. Women with any HFE variant allele had 12% lower blood manganese concentrations than women with no variant alleles (β = -0.12 [95% CI = -0.23 to -0.01]. TF and ALAD variants were not significant predictors of blood manganese. In animal models, Hfe-/- mice displayed a significant reduction in blood manganese compared with Hfe+/+ mice, replicating the altered manganese metabolism found in our human research. Conclusions Our study suggests that genetic variants in iron metabolism genes may contribute to variability in manganese exposure by affecting manganese absorption, distribution, or excretion. Genetic background may be critical to consider in studies that rely on environmental manganese measurements.

Molecular and enzymatic characterization of two enzymes BmPCD and BmDHPR involving in the regeneration pathway of tetrahydrobiopterin from the silkworm Bombyx mori.

Science.gov (United States)

Li, Wentian; Gong, Meixia; Shu, Rui; Li, Xin; Gao, Junshan; Meng, Yan

2015-08-01

Tetrahydrobiopterin (BH4) is an essential cofactor of aromatic amino acid hydroxylases and nitric oxide synthase so that BH4 plays a key role in many biological processes. BH4 deficiency is associated with numerous metabolic syndromes and neuropsychological disorders. BH4 concentration in mammals is maintained through a de novo synthesis pathway and a regeneration pathway. Previous studies showed that the de novo pathway of BH4 is similar between insects and mammals. However, knowledge about the regeneration pathway of BH4 (RPB) is very limited in insects. Several mutants in the silkworm Bombyx mori have been approved to be associated with BH4 deficiency, which are good models to research on the RPB in insects. In this study, homologous genes encoding two enzymes, pterin-4a-carbinolamine dehydratase (PCD) and dihydropteridine reductase (DHPR) involving in RPB have been cloned and identified from B. mori. Enzymatic activity of DHPR was found in the fat body of wild type silkworm larvae. Together with the transcription profiles, it was indicated that BmPcd and BmDhpr might normally act in the RPB of B. mori and the expression of BmDhpr was activated in the brain and sexual glands while BmPcd was expressed in a wider special pattern when the de novo pathway of BH4 was lacked in lemon. Biochemical analyses showed that the recombinant BmDHPR exhibited high enzymatic activity and more suitable parameters to the coenzyme of NADH in vitro. The results in this report give new information about the RPB in B. mori and help in better understanding insect BH4 biosynthetic networks. Copyright © 2015 Elsevier Inc. All rights reserved.

Histidine Metabolism and IGPD Play a Key Role in Cefquinome Inhibiting Biofilm Formation of Staphylococcus xylosus

Directory of Open Access Journals (Sweden)

Yong-hui Zhou

2018-04-01

Full Text Available Staphylococcus xylosus (S. xylosus is an AT-rich and coagulase-negative Staphylococcus (CNS. It is normally regarded as non-pathogenic, however, recent studies have demonstrated that it is related to human opportunistic infections and bovine mastitis. In addition, S. xylosus strains have the ability to form biofilm. Biofilms are also involved in chronic infections and antibiotic resistance, there are only a few reports about cefquinome inhibiting S. xylosus biofilm formation and the protein targets of cefquinome. In our study, we found that sub-MICs of cefquinome were sufficient to inhibit biofilm formation. To investigate the potential protein targets of cefquinome, we used iTRAQ for the analyses of cells at two different conditions: 1/2-MIC (0.125 μg/mL cefquinome treatment and no treatment. Using iTRAQ technique and KEGG database analysis, we found that proteins differently expression in histidine metabolism pathway may play a role in the process by which 1/2-MIC (0.125 μg/mL cefquinome inhibits S. xylosus biofilm formation. Interestingly, we found a sharply down-regulated enzyme [A0A068E9J3 imidazoleglycerol-phosphate dehydratase (IGPD] involved in histidine metabolism pathway in cefquinome-treated cells. We demonstrated the important role of IGPD in sub-MICs cefquinome inhibiting biofilm formation of S. xylosus by gene (hisB knockout, IGPD enzyme activity and histidine content assays. Thus, our data sheds light on important role of histidine metabolism in S. xylosus biofilm formation; especially, IGPD involved in histidine metabolism might play a crucial role in sub-MICs cefquinome inhibition of biofilm formation of S. xylosus, and we propose IGPD as an attractive protein target of cefquinome.

Using biochemical and isotope geochemistry to understand the environmental and public health implications of lead pollution in the lower Guadiana River, Iberia: a freshwater bivalve study.

Science.gov (United States)

Company, R; Serafim, A; Lopes, B; Cravo, A; Shepherd, T J; Pearson, G; Bebianno, M J

2008-11-01

Lead is a natural component of aquatic ecosystems with no known biological role and is highly toxic. Its toxicity stems from its ability to mimic biologically important metals and to produce membrane damage through lipid peroxidation (LPO). Most lead poisoning symptoms are thought to occur by interfering with an essential enzyme, delta-aminolevulinic acid dehydratase (ALAD), the activity of which is markedly inhibited by lead. The purpose of this work was to study the levels and effects of lead pollution (responses of ALAD and oxidative stress biomarker LPO) in the freshwater bivalve Corbicula fluminea along the lower Guadiana River (Portugal and Spain); a major river system impacted by historic mining pollution and more recent anthropogenic inputs. The results show that the enzymatic activity of ALAD is negatively correlated with the total Pb concentration of the whole tissue suggesting that ALAD has considerable potential as a biomarker of lead exposure in C. fluminea. To identify the sources of lead to which bivalves have been exposed, high precision (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)/Pb ratios for C. fluminea confirm that historical mining activities in the Iberian Pyrite Belt are the dominant source of lead pollution in the lower Guadiana River. The isotope patterns however exhibit marked seasonal and geographic variation in response to rainfall and river water management. Locally, other anthropogenic sources of lead have been detected in C. fluminea close to population centres, thus adding to its versatility as a freshwater bio-indicator. Overall, the study highlights the value of natural ecosystems as monitors of water quality and their importance for public health assessment and surveillance.

Using biochemical and isotope geochemistry to understand the environmental and public health implications of lead pollution in the lower Guadiana River, Iberia: A freshwater bivalve study

International Nuclear Information System (INIS)

Company, R.; Serafim, A.; Lopes, B.; Cravo, A.; Shepherd, T.J.; Pearson, G.; Bebianno, M.J.

2008-01-01

Lead is a natural component of aquatic ecosystems with no known biological role and is highly toxic. Its toxicity stems from its ability to mimic biologically important metals and to produce membrane damage through lipid peroxidation (LPO). Most lead poisoning symptoms are thought to occur by interfering with an essential enzyme, δ-aminolevulinic acid dehydratase (ALAD), the activity of which is markedly inhibited by lead. The purpose of this work was to study the levels and effects of lead pollution (responses of ALAD and oxidative stress biomarker LPO) in the freshwater bivalve Corbicula fluminea along the lower Guadiana River (Portugal and Spain); a major river system impacted by historic mining pollution and more recent anthropogenic inputs. The results show that the enzymatic activity of ALAD is negatively correlated with the total Pb concentration of the whole tissue suggesting that ALAD has considerable potential as a biomarker of lead exposure in C. fluminea. To identify the sources of lead to which bivalves have been exposed, high precision 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, 208 Pb/ 204 /Pb ratios for C. fluminea confirm that historical mining activities in the Iberian Pyrite Belt are the dominant source of lead pollution in the lower Guadiana River. The isotope patterns however exhibit marked seasonal and geographic variation in response to rainfall and river water management. Locally, other anthropogenic sources of lead have been detected in C. fluminea close to population centres, thus adding to its versatility as a freshwater bio-indicator. Overall, the study highlights the value of natural ecosystems as monitors of water quality and their importance for public health assessment and surveillance

Haloperidol-loaded lipid-core polymeric nanocapsules reduce DNA damage in blood and oxidative stress in liver and kidneys of rats

Energy Technology Data Exchange (ETDEWEB)

Roversi, Katiane, E-mail: katianeroversi@gmail.com [Universidade Federal de Santa Maria, Programa de Pós-Graduação em Farmacologia (Brazil); Benvegnú, Dalila M., E-mail: dalilabenvegnu@yahoo.com.br [Universidade Federal da Fronteira Sul (UFFS), Bioquímica e Farmacologia (Brazil); Roversi, Karine, E-mail: karineroversi-@hotmail.com [Universidade Federal de Santa Maria (UFSM), Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde (Brazil); Trevizol, Fabíola, E-mail: fatrevizol@yahoo.com.br [Universidade Federal de Santa Maria, Programa de Pós-Graduação em Farmacologia (Brazil); Vey, Luciana T., E-mail: luciana.taschetto@hotmail.com [Universidade Federal de Santa Maria (UFSM), Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde (Brazil); Elias, Fabiana, E-mail: fabiana.elias@uffs.edu.br [Universidade Federal da Fronteira Sul (UFFS), Bioquímica e Farmacologia (Brazil); Fracasso, Rafael, E-mail: rafael.fra@hotmail.com [Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Ciências Farmacêuticas (Brazil); and others

2015-04-15

Haloperidol (HP) nanoencapsulation improves therapeutic efficacy, prolongs the drug action time, and reduces its motor side effects. However, in a view of HP toxicity in organs like liver and kidneys in addition to the lack of knowledge regarding the toxicity of polymeric nanocapsules, our aim was to verify the influence of HP-nanoformulation on toxicity and oxidative stress markers in the liver and kidneys of rats, also observing the damage caused in the blood. For such, 28 adult male Wistar rats were designated in four experimental groups (n = 7) and treated with vehicle (C group), free haloperidol suspension (FH group), blank nanocapsules suspension (B-Nc group), and haloperidol-loaded lipid-core nanocapsules suspension (H-Nc group). The nanocapsules formulation presented the size of approximately 250 nm. All suspensions were administered to the animals (0.5 mg/kg/day-i.p.) for a period of 28 days. Our results showed that FH caused damage in the liver, evidenced by increased lipid peroxidation, plasma levels of aspartate aminotransferase, and alanine aminotransferase, as well as decreased cellular integrity and vitamin C levels. In kidneys, FH treatment caused damage to a lesser extent, observed by decreased activity of δ-aminolevulinate dehydratase (ALA-D) and levels of VIT C. In addition, FH treatment was also related to a higher DNA damage index in blood. On the other hand, animals treated with H-Nc and B-Nc did not show damage in liver, kidneys, and DNA. Our study indicates that the nanoencapsulation of haloperidol was able to prevent the sub-chronic toxicity commonly observed in liver, kidneys, and DNA, thus reflecting a pharmacological superiority in relation to free drug.

Involvement of oxidative stress in 4-vinylcyclohexene-induced toxicity in Drosophila melanogaster.

Science.gov (United States)

Abolaji, Amos Olalekan; Kamdem, Jean Paul; Lugokenski, Thiago Henrique; Nascimento, Thallita Kalar; Waczuk, Emily Pansera; Farombi, Ebenezer Olatunde; Loreto, Élgion Lúcio da Silva; Rocha, João Batista Teixeira

2014-06-01

4-Vinylcyclohexene (VCH) is a dimer of 1,3-butadiene produced as a by-product of pesticides, plastic, rubber, flame retardants, and tire production. Although, several studies have reported the ovotoxicity of VCH, information on a possible involvement of oxidative stress in the toxicity of this occupational chemical is scarce. Hence, this study was carried out to investigate further possible mechanisms of toxicity of VCH with a specific emphasis on oxidative stress using a Drosophila melanogaster model. D. melanogaster (both genders) of 1 to 3 days old were exposed to different concentrations of VCH (10 µM-1 mM) in the diet for 5 days. Subsequently, the survival and negative geotaxis assays and the quantification of reactive oxygen species (ROS) generation were determined. In addition, we evaluated RT-PCR expressions of selected oxidative stress and antioxidant mRNA genes (HSP27, 70, and 83, SOD, Nrf-2, MAPK2, and catalase). Furthermore, catalase, glutathione-S-transferase (GST), delta aminolevulinic acid dehydratase (δ-ALA-D), and acetylcholinesterase (AChE) activities were determined. VCH exposure impaired negative geotaxic behavior and induced the mRNA of SOD, Nrf-2, and MAPK2 genes expressions. There were increases in catalase and ROS production, as well as inhibitions of GST, δ-ALA-D, and AChE activities (Pbalance, and possible neurotoxic consequences due to decreased AChE activity, and impairments in negative geotaxic behavior. Thus, we conclude that D. melanogaster is a useful model for investigating the toxicity of VCH exposure, and here, we have provided further insights on the mechanism of VCH-induced toxicity. Copyright © 2014 Elsevier Inc. All rights reserved.

Highly efficient residue-selective labeling with isotope-labeled Ile, Leu, and Val using a new auxotrophic E. coli strain

International Nuclear Information System (INIS)

Miyanoiri, Yohei; Ishida, Yojiro; Takeda, Mitsuhiro; Terauchi, Tsutomu; Inouye, Masayori; Kainosho, Masatsune

2016-01-01

We recently developed a practical protocol for preparing proteins bearing stereo-selectively 13 C-methyl labeled leucines and valines, instead of the commonly used 13 C-methyl labeled precursors for these amino acids, by E. coli cellular expression. Using this protocol, proteins with any combinations of isotope-labeled or unlabeled Leu and Val residues were prepared, including some that could not be prepared by the precursor methods. However, there is still room for improvement in the labeling efficiencies for Val residues, using the methods with labeled precursors or Val itself. This is due to the fact that the biosynthesis of Val could not be sufficiently suppressed, even by the addition of large amounts of Val or its precursors. In this study, we completely solved this problem by using a mutant strain derived from E. coli BL21(DE3), in which the metabolic pathways depending on two enzymes, dihydroxy acid dehydratase and β-isopropylmalate dehydrogenase, are completely aborted by deleting the ilvD and leuB genes, which respectively encode these enzymes. The ΔilvD E. coli mutant terminates the conversion from α,β-dihydroxyisovalerate to α-ketoisovalerate, and the conversion from α,β-dihydroxy-α-methylvalerate to α-keto-β-methylvalerate, which produce the preceding precursors for Val and Ile, respectively. By the further deletion of the leuB gene, the conversion from Val to Leu was also fully terminated. Taking advantage of the double-deletion mutant, ΔilvDΔleuB E. coli BL21(DE3), an efficient and residue-selective labeling method with various isotope-labeled Ile, Leu, and Val residues was established.

Highly efficient residue-selective labeling with isotope-labeled Ile, Leu, and Val using a new auxotrophic E. coli strain

Energy Technology Data Exchange (ETDEWEB)

Miyanoiri, Yohei [Nagoya University, Structural Biology Research Center, Graduate School of Science (Japan); Ishida, Yojiro [Rutgers University-Robert Wood Johnson Medical School, Center for Advanced Biotechnology and Medicine (United States); Takeda, Mitsuhiro [Nagoya University, Structural Biology Research Center, Graduate School of Science (Japan); Terauchi, Tsutomu [Tokyo Metropolitan University, Graduate School of Science and Engineering (Japan); Inouye, Masayori [Rutgers University-Robert Wood Johnson Medical School, Center for Advanced Biotechnology and Medicine (United States); Kainosho, Masatsune, E-mail: kainosho@tmu.ac.jp [Nagoya University, Structural Biology Research Center, Graduate School of Science (Japan)

2016-06-15

We recently developed a practical protocol for preparing proteins bearing stereo-selectively {sup 13}C-methyl labeled leucines and valines, instead of the commonly used {sup 13}C-methyl labeled precursors for these amino acids, by E. coli cellular expression. Using this protocol, proteins with any combinations of isotope-labeled or unlabeled Leu and Val residues were prepared, including some that could not be prepared by the precursor methods. However, there is still room for improvement in the labeling efficiencies for Val residues, using the methods with labeled precursors or Val itself. This is due to the fact that the biosynthesis of Val could not be sufficiently suppressed, even by the addition of large amounts of Val or its precursors. In this study, we completely solved this problem by using a mutant strain derived from E. coli BL21(DE3), in which the metabolic pathways depending on two enzymes, dihydroxy acid dehydratase and β-isopropylmalate dehydrogenase, are completely aborted by deleting the ilvD and leuB genes, which respectively encode these enzymes. The ΔilvD E. coli mutant terminates the conversion from α,β-dihydroxyisovalerate to α-ketoisovalerate, and the conversion from α,β-dihydroxy-α-methylvalerate to α-keto-β-methylvalerate, which produce the preceding precursors for Val and Ile, respectively. By the further deletion of the leuB gene, the conversion from Val to Leu was also fully terminated. Taking advantage of the double-deletion mutant, ΔilvDΔleuB E. coli BL21(DE3), an efficient and residue-selective labeling method with various isotope-labeled Ile, Leu, and Val residues was established.

Genotypic variability and mutant identification in cicer arietinum L. by seed storage protein profiling

International Nuclear Information System (INIS)

Hameed, A.; Iqbal, N.; Shah, T.M.

2012-01-01

A collection of thirty-four chickpea genotypes, including five kabuli and twenty-nine desi, were analyzed by SDS-PAGE for seed storage protein profiling. Total soluble seed proteins were resolved on 12% gels. A low level of variability was observed in desi as compared to kabuli genotypes. Dendrogram based on electrophoretic data clustered the thirty-four genotypes in four major groups. As large number of desi genotypes illustrated identical profiles, therefore could not be differentiated on the basis of seed storage protein profiles. One kabuli genotype ILC-195 found to be the most divergent showing 86% similarity with all other genotypes. ILC-195 can be distinguished from its mutant i.e., CM-2000 and other kabuli genotypes on the basis of three peptides i.e. SSP-66, SSP-43 and SSP-39. Some proteins peptides were found to be genotype specific like SSP-26 for ICCV-92311. Uniprot and NCBI protein databases were searched for already reported and characterized seed storage proteins in chickpea. Among 33 observed peptides, only six seed storages proteins from chickpea source were available in databases. On the basis of molecular weight similarity, identified peptides were SSP-64 as Serine/Threonine dehydratase, SSP-56 as Alpha-amylase inhibitor, SSP-50 as Provicillin, SSP-39 as seed imbibition protein, SSP-35 as Isoflavane reductase and SSP-19 as lipid transport protein. Highest variability was observed in vicillin subunits and beta subunits of legumins and its polymorphic forms. In conclusion, seed storage profiling can be economically used to asses the genetic variation, phylogenetic relationship and as markers to differentiate mutants from their parents. (author)

In vitro glutathione peroxidase mimicry of ebselen is linked to its oxidation of critical thiols on key cerebral suphydryl proteins - A novel component of its GPx-mimic antioxidant mechanism emerging from its thiol-modulated toxicology and pharmacology.

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Kade, I J; Balogun, B D; Rocha, J B T

2013-10-25

The antioxidant mechanism of ebselen in rats brain is largely linked with its glutathione peroxidase (GPx) rather than its peroxiredoxin mimicry ability. However, the precise molecular dynamics between the GPx-mimicry of ebselen and thiol utilization is yet to be fully clarified and thus still open. Herein, we investigated the influence of dithiothreitol (DTT) on the antioxidant action of ebselen against oxidant-induced cerebral lipid peroxidation and deoxyribose degradation. Furthermore, the critical inhibitory concentrations of ebselen on the activities of sulphydryl enzymes such as cerebral sodium pump, δ-aminolevulinic acid dehydratase (δ-ALAD) and lactate dehydrogenase (LDH) were also investigated. We observe that ebselen (at ≥42 μM) markedly inhibited lipid peroxidation in the presence and absence of DTT, whereas it inhibited deoxyribose degradation only in the presence of DTT. Furthermore, under in vitro conditions, ebselen inhibited the thiol containing enzymes; cerebral sodium pump (at ≥40 μM), δ-ALAD (≥10 μM) and LDH (≥1 μM) which were either prevented or reversed by DTT. However, the inhibition of the activities of these sulphydryl proteins in diabetic animals was prevented by ebselen. Summarily, it is apparent that the effective in vitro inhibitory doses of ebselen on the activity of the sulphydryl proteins are far less than its antioxidant doses. In addition, the presence of DTT is evidently a critical requirement for ebselen to effect its antioxidant action against deoxyribose degeradation and not lipid peroxidation. Consequently, we conclude that ebselen possibly utilizes available thiols on sulphydryl proteins to effect its GPx mimicry antioxidant action against lipid peroxidation in rat brain homogenate. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Ebselen protects against behavioral and biochemical toxicities induced by 3-nitropropionic acid in rats: correlations between motor coordination, reactive species levels, and succinate dehydrogenase activity.

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Wilhelm, Ethel A; Bortolatto, Cristiani F; Jesse, Cristiano R; Luchese, Cristiane

2014-12-01

The protective effect of ebselen was investigated against 3-nitropropionic acid (3-NP)-induced behavioral and biochemical toxicities in rats. Ebselen (10 or 25 mg/kg, intragastrically) was administered to rats 30 min before 3-NP (20 mg/kg, intraperitoneally) once a day for a period of 4 days. Locomotor activity, motor coordination, and body weight gain were determined. The striatal content of reactive oxygen species (ROS), reduced glutathione (GSH), ascorbic acid (AA), and protein carbonyl as well as catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-S-transferase (GST) activities was determined 24 h after the last dose of 3-NP. Na(+)/ K(+)-ATPase, succinate dehydrogenase (SDH), and δ-aminolevulinic dehydratase (δ-ALA-D) activities were also determined. The results demonstrated that ebselen at a dose of 25 mg/kg, but not at 10 mg/kg, protected against (1) a decrease in locomotor activity, motor coordination impairment, and body weight loss; (2) striatal oxidative damage, which was characterized by an increase in ROS levels, protein carbonyl content, and GR activity, an inhibition of CAT and GPx activities, and a decrease in GSH levels; and (3) an inhibition of SDH and Na(+)/K(+)-ATPase activities, induced by 3-NP. GST activity and AA levels were not modified by ebselen or 3-NP. Ebselen was not effective against the inhibition of δ-ALA-D activity induced by 3-NP. The results revealed a significant correlation between SDH activity and ROS levels, and SDH activity and latency to fall (rotarod test). The present study highlighted the protective effect of ebselen against 3-NP-induced toxicity in rats.

Behavior of lead and zinc in plasma, erythrocytes, and urine and ALAD in erythrocytes following intravenous infusion of CaEDTA in lead workers.

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Araki, S; Aono, H; Fukahori, M; Tabuki, K

1984-01-01

To evaluate the effect of calcium disodium ethylenediamine tetraacetate (CaEDTA) on concentrations of lead and zinc in plasma, erythrocytes, whole blood, and urine, we administered CaEDTA by intravenous infusion for 1 hr to seven lead workers with blood lead concentrations of 46-67 micrograms/100 g (mean 54 micrograms/100 g). The plasma lead concentration (PPb) and the mobilization yield of lead in urine by CaEDTA were highest during the period between 1 and 2 hr after the infusion was started. In contrast, the lead concentration in erythrocytes (EPb) and in whole blood (BPb) remained unchanged during the 24 hr following infusion. Plasma zinc concentration (PZn) also fell rapidly following CaEDTA infusion; the decline was followed by a gradual rise in the zinc concentration in erythrocytes (EZn) without alteration in the zinc in whole blood. The mobilization yield of zinc in urine by CaEDTA (MZn) reached its highest level within 1 hr after the start of the infusion. Delta-aminolevulinic acid dehydratase (ALAD) activity in erythrocytes gradually increased for 5 hr following CaEDTA infusion. These observations suggest that (1) PPb concentration is a more sensitive indicator of the body burden of chelatable lead than is either BPb or EPb; (2) MZn is mobilized mostly from plasma during the first several hours following the start of CaEDTA infusion, and the fall in PZn concentration following infusion is compensated first by a rise in EZn concentration and then by an immediate redistribution of zinc in other organs to the blood; and (3) Pb-inhibited ALAD activity is reactivated by the increased EZn during and shortly after CaEDTA infusion.

Analysis of the Staphylococcus aureus capsule biosynthesis pathway in vitro: characterization of the UDP-GlcNAc C6 dehydratases CapD and CapE and identification of enzyme inhibitors.

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Li, Wenjin; Ulm, Hannah; Rausch, Marvin; Li, Xue; O'Riordan, Katie; Lee, Jean C; Schneider, Tanja; Müller, Christa E

2014-11-01

Polysaccharide capsules significantly contribute to virulence of invasive pathogens, and inhibition of capsule biosynthesis may offer a valuable strategy for novel anti-infective treatment. We purified and characterized the enzymes CapD and CapE of the Staphylococcus aureus serotype 5 biosynthesis cluster, which catalyze the first steps in the synthesis of the soluble capsule precursors UDP-D-FucNAc and UDP-L-FucNAc, respectively. CapD is an integral membrane protein and was obtained for the first time in a purified, active form. A capillary electrophoresis (CE)-based method applying micellar electrokinetic chromatography (MEKC) coupled with UV detection at 260 nm was developed for functional characterization of the enzymes using a fused-silica capillary, electrokinetic injection, and dynamic coating with polybrene at pH 12.4. The limits of detection for the CapD and CapE products UDP-2-acetamido-2,6-dideoxy-α-D-xylo-hex-4-ulose and UDP-2-acetamido-2,6-dideoxy-β-L-arabino-hex-4-ulose, respectively, were below 1 μM. Using this new, robust and sensitive method we performed kinetic studies for CapD and CapE and screened a compound library in search for enzyme inhibitors. Several active compounds were identified and characterized, including suramin (IC50 at CapE 1.82 μM) and ampicillin (IC50 at CapD 40.1 μM). Furthermore, the cell wall precursors UDP-D-MurNAc-pentapeptide and lipid II appear to function as inhibitors of CapD enzymatic activity, suggesting an integrated mechanism of regulation for cell envelope biosynthesis pathways in S. aureus. Corroborating the in vitro findings, staphylococcal cells grown in the presence of subinhibitory concentrations of ampicillin displayed drastically reduced CP production. Our studies contribute to a profound understanding of the capsule biosynthesis in pathogenic bacteria. This approach may lead to the identification of novel anti-virulence and antibiotic drugs. Copyright © 2014 Elsevier GmbH. All rights reserved.

Effect of vitamin D3 on behavioural and biochemical parameters in diabetes type 1-induced rats.

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Calgaroto, Nicéia Spanholi; Thomé, Gustavo Roberto; da Costa, Pauline; Baldissareli, Jucimara; Hussein, Fátima Abdala; Schmatz, Roberta; Rubin, Maribel A; Signor, Cristiane; Ribeiro, Daniela Aymone; Carvalho, Fabiano Barbosa; de Oliveira, Lizielle Souza; Pereira, Luciane Belmonte; Morsch, Vera Maria; Schetinger, Maria Rosa Chitolina

2014-08-01

Diabetes is associated with long-term complications in the brain and reduced cognitive ability. Vitamin D3 (VD3 ) appears to be involved in the amelioration of hyperglycaemia in streptozotocin (STZ)-induced diabetic rats. Our aim was to analyse the potential of VD3 in avoiding brain damage through evaluation of acetylcholinesterase (AChE), Na(+) K(+) -adenosine triphosphatase (ATPase) and delta aminolevulinate dehydratase (δ-ALA-D) activities and thiobarbituric acid reactive substance (TBARS) levels from cerebral cortex, as well as memory in STZ-induced diabetic rats. Animals were divided into eight groups (n = 5): control/saline, control/metformin (Metf), control/VD3 , control/Metf + VD3 , diabetic/saline, diabetic/Metf, diabetic/VD3 and diabetic/Metf + VD3 . Thirty days after treatment, animals were submitted to contextual fear-conditioning and open-field behavioural tests, after which they were sacrificed and the cerebral cortex was dissected. Our results demonstrate a significant memory deficit, an increase in AChE activity and TBARS levels and a decrease in δ-ALA-D and Na(+) K(+) -ATPase activities in diabetic rats when compared with the controls. Treatment of diabetic rats with Metf and VD3 prevented the increase in AChE activity when compared with the diabetic/saline group. In treated diabetic rats, the decrease in Na(+) K(+) -ATPase was reverted when compared with non-treated rats, but the increase in δ-ALA-D activity was not. VD3 prevented diabetes-induced TBARS level and improved memory. Our results show that VD3 can avoid cognitive deficit through prevention of changes in important enzymes such as Na(+) K(+) -ATPase and AChE in cerebral cortex in type 1 diabetic rats. Copyright © 2014 John Wiley & Sons, Ltd.

Efficient production of free fatty acids from soybean meal carbohydrates.

Science.gov (United States)

Wang, Dan; Thakker, Chandresh; Liu, Ping; Bennett, George N; San, Ka-Yiu

2015-11-01

Conversion of biomass feedstock to chemicals and fuels has attracted increasing attention recently. Soybean meal, containing significant quantities of carbohydrates, is an inexpensive renewable feedstock. Glucose, galactose, and fructose can be obtained by enzymatic hydrolysis of soluble carbohydrates of soybean meal. Free fatty acids (FFAs) are valuable molecules that can be used as precursors for the production of fuels and other value-added chemicals. In this study, free fatty acids were produced by mutant Escherichia coli strains with plasmid pXZ18Z (carrying acyl-ACP thioesterase (TE) and (3R)-hydroxyacyl-ACP dehydratase) using individual sugars, sugar mixtures, and enzymatic hydrolyzed soybean meal extract. For individual sugar fermentations, strain ML211 (MG1655 fadD(-) fabR(-) )/pXZ18Z showed the best performance, which produced 4.22, 3.79, 3.49 g/L free fatty acids on glucose, fructose, and galactose, respectively. While the strain ML211/pXZ18Z performed the best with individual sugars, however, for sugar mixture fermentation, the triple mutant strain XZK211 (MG1655 fadD(-) fabR(-) ptsG(-) )/pXZ18Z with an additional deletion of ptsG encoding the glucose-specific transporter, functioned the best due to relieved catabolite repression. This strain produced approximately 3.18 g/L of fatty acids with a yield of 0.22 g fatty acids/g total sugar. Maximum free fatty acids production of 2.78 g/L with a high yield of 0.21 g/g was achieved using soybean meal extract hydrolysate. The results suggested that soybean meal carbohydrates after enzymatic treatment could serve as an inexpensive feedstock for the efficient production of free fatty acids. © 2015 Wiley Periodicals, Inc.

Comprehensive analysis of 5-aminolevulinic acid dehydrogenase (ALAD variants and renal cell carcinoma risk among individuals exposed to lead.

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Dana M van Bemmel

Full Text Available BACKGROUND: Epidemiologic studies are reporting associations between lead exposure and human cancers. A polymorphism in the 5-aminolevulinic acid dehydratase (ALAD gene affects lead toxicokinetics and may modify the adverse effects of lead. METHODS: The objective of this study was to evaluate single-nucleotide polymorphisms (SNPs tagging the ALAD region among renal cancer cases and controls to determine whether genetic variation alters the relationship between lead and renal cancer. Occupational exposure to lead and risk of cancer was examined in a case-control study of renal cell carcinoma (RCC. Comprehensive analysis of variation across the ALAD gene was assessed using a tagging SNP approach among 987 cases and 1298 controls. Occupational lead exposure was estimated using questionnaire-based exposure assessment and expert review. Odds ratios (OR and 95% confidence intervals (CI were calculated using logistic regression. RESULTS: The adjusted risk associated with the ALAD variant rs8177796(CT/TT was increased (OR = 1.35, 95%CI = 1.05-1.73, p-value = 0.02 when compared to the major allele, regardless of lead exposure. Joint effects of lead and ALAD rs2761016 suggest an increased RCC risk for the homozygous wild-type and heterozygous alleles ((GGOR = 2.68, 95%CI = 1.17-6.12, p = 0.01; (GAOR = 1.79, 95%CI = 1.06-3.04 with an interaction approaching significance (p(int = 0.06. No significant modification in RCC risk was observed for the functional variant rs1800435(K68N. Haplotype analysis identified a region associated with risk supporting tagging SNP results. CONCLUSION: A common genetic variation in ALAD may alter the risk of RCC overall, and among individuals occupationally exposed to lead. Further work in larger exposed populations is warranted to determine if ALAD modifies RCC risk associated with lead exposure.

Case-only gene-environment interaction between ALAD tagSNPs and occupational lead exposure in prostate cancer.

Science.gov (United States)

Neslund-Dudas, Christine; Levin, Albert M; Rundle, Andrew; Beebe-Dimmer, Jennifer; Bock, Cathryn H; Nock, Nora L; Jankowski, Michelle; Datta, Indrani; Krajenta, Richard; Dou, Q Ping; Mitra, Bharati; Tang, Deliang; Rybicki, Benjamin A

2014-05-01

Black men have historically had higher blood lead levels than white men in the U.S. and have the highest incidence of prostate cancer in the world. Inorganic lead has been classified as a probable human carcinogen. Lead (Pb) inhibits delta-aminolevulinic acid dehydratase (ALAD), a gene recently implicated in other genitourinary cancers. The ALAD enzyme is involved in the second step of heme biosynthesis and is an endogenous inhibitor of the 26S proteasome, a master system for protein degradation and a current target of cancer therapy. Using a case-only study design, we assessed potential gene-environment (G × E) interactions between lifetime occupational Pb exposure and 11 tagSNPs within ALAD in black (N = 260) and white (N = 343) prostate cancer cases. Two ALAD tagSNPs in high linkage disequilibrium showed significant interaction with high Pb exposure among black cases (rs818684 interaction odds ratio or IOR = 2.73, 95% CI 1.43-5.22, P = 0.002; rs818689 IOR = 2.20, 95% CI 1.15-4.21, P = 0.017) and an additional tagSNP, rs2761016, showed G × E interaction with low Pb exposure (IOR = 2.08, 95% CI 1.13-3.84, P = 0.019). Further, the variant allele of rs818684 was associated with a higher Gleason grade in those with high Pb exposure among both blacks (OR 3.96, 95% CI 1.01-15.46, P = 0.048) and whites (OR 2.95, 95% CI 1.18-7.39, P = 0.020). Genetic variation in ALAD may modify associations between Pb and prostate cancer. Additional studies of ALAD, Pb, and prostate cancer are warranted and should include black men. Prostate 74:637-646, 2014. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.

Synthesis, antitubercular activity and mechanism of resistance of highly effective thiacetazone analogues.

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Geoffrey D Coxon

Full Text Available Defining the pharmacological target(s of currently used drugs and developing new analogues with greater potency are both important aspects of the search for agents that are effective against drug-sensitive and drug-resistant Mycobacterium tuberculosis. Thiacetazone (TAC is an anti-tubercular drug that was formerly used in conjunction with isoniazid, but removed from the antitubercular chemotherapeutic arsenal due to toxic side effects. However, several recent studies have linked the mechanisms of action of TAC to mycolic acid metabolism and TAC-derived analogues have shown increased potency against M. tuberculosis. To obtain new insights into the molecular mechanisms of TAC resistance, we isolated and analyzed 10 mutants of M. tuberculosis that were highly resistant to TAC. One strain was found to be mutated in the methyltransferase MmaA4 at Gly101, consistent with its lack of oxygenated mycolic acids. All remaining strains harbored missense mutations in either HadA (at Cys61 or HadC (at Val85, Lys157 or Thr123, which are components of the β-hydroxyacyl-ACP dehydratase complex that participates in the mycolic acid elongation step. Separately, a library of 31 new TAC analogues was synthesized and evaluated against M. tuberculosis. Two of these compounds, 15 and 16, exhibited minimal inhibitory concentrations 10-fold lower than the parental molecule, and inhibited mycolic acid biosynthesis in a dose-dependent manner. Moreover, overexpression of HadAB HadBC or HadABC in M. tuberculosis led to high level resistance to these compounds, demonstrating that their mode of action is similar to that of TAC. In summary, this study uncovered new mutations associated with TAC resistance and also demonstrated that simple structural optimization of the TAC scaffold was possible and may lead to a new generation of TAC-derived drug candidates for the potential treatment of tuberculosis as mycolic acid inhibitors.

Effects of TiO2 nanoparticles on nutrition metabolism in silkworm fat body

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J. H. Tian

2016-06-01

Full Text Available Silkworm (Bombyx mori is an important economic insect with a fat body that plays a crucial role in the storage and transfer of nutrients. It is also known that TiO2 nanoparticles (NPs can improve feed efficiency and promote silk protein synthesis in the silkworm. In this study, we profiled gene expression in the silkworm fat body after TiO2 NP treatment, validated the major RNA-seq findings, and determined the contents of trehalose and triglyceride, the activity of lipase, and the amount of total proteins. RNA-seq analysis revealed that TiO2 NP treatment caused significant expression changes in 341 genes (P≤0.01, 138 of which were upregulated while the other 203 were downregulated. The expression levels of two target genes in the insulin signaling pathway and two protein metabolism-related target genes, three lipid metabolism-associated target genes, two carbohydrate metabolism related target genes and expression levels of seven heat shock protein genes were increased, and that of threonine dehydratase gene and fatty acid transport protein gene were decreased. The RNA-seq results of 16 genes were validated by quantitative real-time PCR. The lipase activity, content of trehalose, and amount of total proteins were elevated by 3.86-fold, 1.34-fold, and 1.21-fold, respectively, and the content of triglyceride was decreased by 0.94-fold after TiO2 NP treatment. These results indicated that TiO2 NPs activated the insulin signaling pathway, promoted the metabolism of protein, fat, and carbohydrate, and improved nutrition metabolism. Our study provides new support for the understanding of the beneficial effect of TiO2 NPs on silkworm nutrient metabolism.

Kinetic Stability May Determine the Interaction Dynamics of the Bifunctional Protein DCoH1, the Dimerization Cofactor of the Transcription Factor HNF-1[alpha

Energy Technology Data Exchange (ETDEWEB)

Rho, H.; Jones, C.N.; Rose, R.B. (NCSU)

2010-12-07

The two disparate functions of DCoH1 (dimerization cofactor of HNF-1)/PCD (pterin-4a-carbinolamine dehydratase) are associated with a change in oligomeric state. DCoH dimers enhance the activity of the diabetes-associated transcription factor HNF-1{alpha} (hepatocyte nuclear factor-1{alpha}), while the PCD activity of DCoH1 homotetramers aids in aromatic amino acid metabolism. These complexes compete for the same interface of the DCoH dimer. Formation of the DCoH1/HNF-1{alpha} complex requires cofolding. The homotetramer of the DCoH1 paralogue, DCoH2, interacts with HNF-1{alpha} through simple mixing. To further investigate regulation of DCoH/HNF-1{alpha} complex formation, we measured the stability of the DCoH1 homotetramer through unfolding studies by intrinsic tryptophan fluorescence. DCoH2 unfolding is reversible. Surprisingly, the DCoH1 homotetramer is resistant to guanidine unfolding but refolds at a much lower guanidine concentration. We show that a point mutation at the DCoH1 tetramer interface, Thr 51 Ser, overcomes the dissociation barrier of the homotetramer and increases the interaction with HNF-1{alpha}. The 1.8 {angstrom} resolution crystal structure of DCoH1 T51S shows the presence of an ordered water molecule at the tetramer interface, as in DCoH2, which may destabilize the homotetramer. The equilibrium unfolding data were fit to a two-state model with no apparent intermediate. Folding intermediates were detectable by size exclusion chromatography. For wild-type DCoH1 the intermediates changed with time, suggesting a kinetic origin for the unfolding barrier of the homotetramer. We propose an unfolding pathway in which the tetramer unfolds slowly, but the dimer folds reversibly. Implications for regulation of DCoH1/HNF-1{alpha} complex formation are discussed.

Nitrile Metabolizing Yeasts

Science.gov (United States)

Bhalla, Tek Chand; Sharma, Monica; Sharma, Nitya Nand

Nitriles and amides are widely distributed in the biotic and abiotic components of our ecosystem. Nitrile form an important group of organic compounds which find their applications in the synthesis of a large number of compounds used as/in pharmaceutical, cosmetics, plastics, dyes, etc>. Nitriles are mainly hydro-lyzed to corresponding amide/acid in organic chemistry. Industrial and agricultural activities have also lead to release of nitriles and amides into the environment and some of them pose threat to human health. Biocatalysis and biotransformations are increasingly replacing chemical routes of synthesis in organic chemistry as a part of ‘green chemistry’. Nitrile metabolizing organisms or enzymes thus has assumed greater significance in all these years to convert nitriles to amides/ acids. The nitrile metabolizing enzymes are widely present in bacteria, fungi and yeasts. Yeasts metabolize nitriles through nitrilase and/or nitrile hydratase and amidase enzymes. Only few yeasts have been reported to possess aldoxime dehydratase. More than sixty nitrile metabolizing yeast strains have been hither to isolated from cyanide treatment bioreactor, fermented foods and soil. Most of the yeasts contain nitrile hydratase-amidase system for metabolizing nitriles. Transformations of nitriles to amides/acids have been carried out with free and immobilized yeast cells. The nitrilases of Torulopsis candida>and Exophiala oligosperma>R1 are enantioselec-tive and regiospecific respectively. Geotrichum>sp. JR1 grows in the presence of 2M acetonitrile and may have potential for application in bioremediation of nitrile contaminated soil/water. The nitrilase of E. oligosperma>R1 being active at low pH (3-6) has shown promise for the hydroxy acids. Immobilized yeast cells hydrolyze some additional nitriles in comparison to free cells. It is expected that more focus in future will be on purification, characterization, cloning, expression and immobilization of nitrile metabolizing

A four-gene operon in Bacillus cereus produces two rare spore-decorating sugars.

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Li, Zi; Mukherjee, Thiya; Bowler, Kyle; Namdari, Sholeh; Snow, Zachary; Prestridge, Sarah; Carlton, Alexandra; Bar-Peled, Maor

2017-05-05

Bacterial glycan structures on cell surfaces are critical for cell-cell recognition and adhesion and in host-pathogen interactions. Accordingly, unraveling the sugar composition of bacterial cell surfaces can shed light on bacterial growth and pathogenesis. Here, we found that two rare sugars with a 3- C -methyl-6-deoxyhexose structure were linked to spore glycans in Bacillus cereus ATCC 14579 and ATCC 10876. Moreover, we identified a four-gene operon in B. cereus ATCC 14579 that encodes proteins with the following sequential enzyme activities as determined by mass spectrometry and one- and two-dimensional NMR methods: CTP:glucose-1-phosphate cytidylyltransferase, CDP-Glc 4,6-dehydratase, NADH-dependent SAM: C -methyltransferase, and NADPH-dependent CDP-3- C -methyl-6-deoxyhexose 4-reductase. The last enzyme predominantly yielded CDP-3- C -methyl-6-deoxygulose (CDP-cereose) and likely generated a 4-epimer CDP-3- C -methyl-6-deoxyallose (CDP-cillose). Some members of the B. cereus sensu lato group produce CDP-3- C -methyl-6-deoxy sugars for the formation of cereose-containing glycans on spores, whereas others such as Bacillus anthracis do not. Gene knockouts of the Bacillus C -methyltransferase and the 4-reductase confirmed their involvement in the formation of cereose-containing glycan on B. cereus spores. We also found that cereose represented 0.2-1% spore dry weight. Moreover, mutants lacking cereose germinated faster than the wild type, yet the mutants exhibited no changes in sporulation or spore resistance to heat. The findings reported here may provide new insights into the roles of the uncommon 3- C -methyl-6-deoxy sugars in cell-surface recognition and host-pathogen interactions of the genus Bacillus . © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Metabolic engineering of Corynebacterium glutamicum to produce GDP-L-fucose from glucose and mannose.

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Chin, Young-Wook; Park, Jin-Byung; Park, Yong-Cheol; Kim, Kyoung Heon; Seo, Jin-Ho

2013-06-01

Wild-type Corynebacterium glutamicum was metabolically engineered to convert glucose and mannose into guanosine 5'-diphosphate (GDP)-L-fucose, a precursor of fucosyl-oligosaccharides, which are involved in various biological and pathological functions. This was done by introducing the gmd and wcaG genes of Escherichia coli encoding GDP-D-mannose-4,6-dehydratase and GDP-4-keto-6-deoxy-D-mannose-3,5-epimerase-4-reductase, respectively, which are known as key enzymes in the production of GDP-L-fucose from GDP-D-mannose. Coexpression of the genes allowed the recombinant C. glutamicum cells to produce GDP-L-fucose in a minimal medium containing glucose and mannose as carbon sources. The specific product formation rate was much higher during growth on mannose than on glucose. In addition, the specific product formation rate was further increased by coexpressing the endogenous phosphomanno-mutase gene (manB) and GTP-mannose-1-phosphate guanylyl-transferase gene (manC), which are involved in the conversion of mannose-6-phosphate into GDP-D-mannose. However, the overexpression of manA encoding mannose-6-phosphate isomerase, catalyzing interconversion of mannose-6-phosphate and fructose-6-phosphate showed a negative effect on formation of the target product. Overall, coexpression of gmd, wcaG, manB and manC in C. glutamicum enabled production of GDP-L-fucose at the specific rate of 0.11 mg g cell(-1) h(-1). The specific GDP-L-fucose content reached 5.5 mg g cell(-1), which is a 2.4-fold higher than that of the recombinant E. coli overexpressing gmd, wcaG, manB and manC under comparable conditions. Well-established metabolic engineering tools may permit optimization of the carbon and cofactor metabolisms of C. glutamicum to further improve their production capacity.

In Vivo-Selected Compensatory Mutations Restore the Fitness Cost of Mosaic penA Alleles That Confer Ceftriaxone Resistance in Neisseria gonorrhoeae

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Leah R. Vincent

2018-04-01

Full Text Available Resistance to ceftriaxone in Neisseria gonorrhoeae is mainly conferred by mosaic penA alleles that encode penicillin-binding protein 2 (PBP2 variants with markedly lower rates of acylation by ceftriaxone. To assess the impact of these mosaic penA alleles on gonococcal fitness, we introduced the mosaic penA alleles from two ceftriaxone-resistant (Cror clinical isolates (H041 and F89 into a Cros strain (FA19 by allelic exchange and showed that the resultant Cror mutants were significantly outcompeted by the Cros parent strain in vitro and in a murine infection model. Four Cror compensatory mutants of FA19 penA41 were isolated independently from mice that outcompeted the parent strain both in vitro and in vivo. One of these compensatory mutants (LV41C displayed a unique growth profile, with rapid log growth followed by a sharp plateau/gradual decline at stationary phase. Genome sequencing of LV41C revealed a mutation (G348D in the acnB gene encoding the bifunctional aconitate hydratase 2/2 methylisocitrate dehydratase. Introduction of the acnBG348D allele into FA19 penA41 conferred both a growth profile that phenocopied that of LV41C and a fitness advantage, although not as strongly as that exhibited by the original compensatory mutant, suggesting the existence of additional compensatory mutations. The mutant aconitase appears to be a functional knockout with lower activity and expression than wild-type aconitase. Transcriptome sequencing (RNA-seq analysis of FA19 penA41 acnBG348D revealed a large set of upregulated genes involved in carbon and energy metabolism. We conclude that compensatory mutations can be selected in Cror gonococcal strains that increase metabolism to ameliorate their fitness deficit.

Lead-Related Genetic Loci, Cumulative Lead Exposure and Incident Coronary Heart Disease: The Normative Aging Study

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Weisskopf, Marc G.; Sparrow, David; Schwartz, Joel; Hu, Howard; Park, Sung Kyun

2016-01-01

Background Cumulative exposure to lead is associated with cardiovascular outcomes. Polymorphisms in the δ-aminolevulinic acid dehydratase (ALAD), hemochromatosis (HFE), heme oxygenase-1 (HMOX1), vitamin D receptor (VDR), glutathione S-transferase (GST) supergene family (GSTP1, GSTT1, GSTM1), apolipoprotein E (APOE),angiotensin II receptor-1 (AGTR1) and angiotensinogen (AGT) genes, are believed to alter toxicokinetics and/or toxicodynamics of lead. Objectives We assessed possible effect modification by genetic polymorphisms in ALAD, HFE, HMOX1, VDR, GSTP1, GSTT1, GSTM1, APOE, AGTR1 and AGT individually and as the genetic risk score (GRS) on the association between cumulative lead exposure and incident coronary heart disease (CHD) events. Methods We used K-shell-X-ray fluorescence to measure bone lead levels. GRS was calculated on the basis of 22 lead-related loci. We constructed Cox proportional hazard models to compute adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for incident CHD. We applied inverse probability weighting to account for potential selection bias due to recruitment into the bone lead sub-study. Results Significant effect modification was found by VDR, HMOX1, GSTP1, APOE, and AGT genetic polymorphisms when evaluated individually. Further, the bone lead-CHD associations became larger as GRS increases. After adjusting for potential confounders, a HR of CHD was 2.27 (95%CI: 1.50–3.42) with 2-fold increase in patella lead levels, among participants in the top tertile of GRS. We also detected an increasing trend in HRs across tertiles of GRS (p-trend = 0.0063). Conclusions Our findings suggest that lead-related loci as a whole may play an important role in susceptibility to lead-related CHD risk. These findings need to be validated in a separate cohort containing bone lead, lead-related genetic loci and incident CHD data. PMID:27584680

Stereochemistry of 1,2-elimination and proton-transfer reactions: toward a unified understanding.

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Mohrig, Jerry R

2013-07-16

Many mechanistic and stereochemical studies have focused on the breaking of the C-H bond through base-catalyzed elimination reactions. When we began our research, however, chemists knew almost nothing about the stereospecificity of addition-elimination reactions involving conjugated acyclic carbonyl compounds, even though the carbonyl group is a pivotal functional group in organic chemistry. Over the last 25 years, we have studied the addition-elimination reactions of β-substituted acyclic esters, thioesters, and ketones in order to reach a comprehensive understanding of how electronic effects influence their stereochemistry. This Account brings together our understanding of the stereochemistry of 1,2-elimination and proton-transfer reactions, describing how each study has built upon previous work and contributed to our understanding of this field. When we began, chemists thought that anti stereospecificity in base-catalyzed 1,2-elimination reactions occurred via concerted E2 mechanisms, which provide a smooth path for anti elimination. Unexpectedly, we discovered that some E1cBirrev reactions produce the same anti stereospecificity as E2 reactions even though they proceed through diffusionally equilibrated, "free" enolate-anion intermediates. This result calls into question the conventional wisdom that anti stereochemistry must result from a concerted mechanism. While carrying out our research, we developed insights ranging from the role of historical contingency in the evolution of hydratase-dehydratase enzymes to the influence of buffers on the stereochemistry of H/D exchange in D2O. Negative hyperconjugation is the most important concept for understanding our results. This idea provides a unifying view for the largely anti stereochemistry in E1cBirrev elimination reactions and a basis for understanding the stereoelectronic influence of electron-withdrawing β-substituents on proton-transfer reactions.

Ovotoxicants 4-vinylcyclohexene 1,2-monoepoxide and 4-vinylcyclohexene diepoxide disrupt redox status and modify different electrophile sensitive target enzymes and genes in Drosophila melanogaster

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Amos O. Abolaji

2015-08-01

Full Text Available The compounds 4-vinylcyclohexene 1,2-monoepoxide (VCM and 4-Vinylcyclohexene diepoxide (VCD are the two downstream metabolites of 4-vinylcyclohexene (VCH, an ovotoxic agent in mammals. In addition, VCM and VCD may be found as by-products of VCH oxidation in the environment. Recently, we reported the involvement of oxidative stress in the toxicity of VCH in Drosophila melanogaster. However, it was not possible to determine the individual contributions of VCM and VCD in VCH toxicity. Hence, we investigated the toxicity of VCM and VCD (10–1000 µM in flies after 5 days of exposure via the diet. Our results indicated impairments in climbing behaviour and disruptions in antioxidant balance and redox status evidenced by an increase in DCFH oxidation, decreases in total thiol content and glutathione-S-transferase (GST activity in the flies exposed to VCM and VCD (p<0.05. These effects were accompanied by disruptions in the transcription of the genes encoding the proteins superoxide dismutase (SOD1, kelch-like erythroid-derived cap-n-collar (CNC homology (ECH-associated protein 1 (Keap-1, mitogen activated protein kinase 2 (MAPK-2, catalase, Cyp18a1, JAFRAC 1 (thioredoxin peroxidase 1 and thioredoxin reductase 1 (TrxR-1 (p<0.05. VCM and VCD inhibited acetylcholinesterase (AChE and delta aminolevulinic acid dehydratase (δ-ALA D activities in the flies (p<0.05. Indeed, here, we demonstrated that different target enzymes and genes were modified by the electrophiles VCM and VCD in the flies. Thus, D. melanogaster has provided further lessons on the toxicity of VCM and VCD which suggest that the reported toxicity of VCH may be mediated by its transformation to VCM and VCD.

Vestibular characterization in the menstrual cycle Caracterização vestibular no ciclo menstrual

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Cintia Ishii

2009-06-01

Full Text Available Hormonal disorders in the menstrual cycle can affect labyrinthine fluid homeostasis, causing balance and hearing dysfunctions. STUDY DESIGN: Clinical prospective. AIM: compare the results from vestibular tests in young women, in the premenstrual and postmenstrual periods. MATERIALS AND METHODS: twenty women were selected with ages ranging from 18 to 35 years, who were not using any kind of contraceptive method for at least six months, and without vestibular or hearing complaints. The test was carried out in each subject before and after the menstrual period, respecting the limit of ten days before or after menstruation. RESULTS: there was a statistically significant difference in the menstrual cycle phases only in the following vestibular tests: calibration, saccadic movements, PRPD and caloric-induced nystagmus. We also noticed that age; a regular menstrual cycle; hearing loss or dizziness cases in the family; and premenstrual symptoms such as tinnitus, headache, sleep disorders, anxiety, nausea and hyperacusis can interfere in the vestibular test. CONCLUSION: there are differences in the vestibular tests of healthy women when comparing their pre and postmenstrual periods.As alterações hormonais do ciclo menstrual podem comprometer a homeostase dos fluidos labirínticos, gerando alterações no equilíbrio e na audição. FORMA DO ESTUDO: Clínico prospectivo. OBJETIVO: Comparar os resultados dos testes do exame vestibular em mulheres jovens, nos períodos pré e pós-menstrual. MATERIAL E MÉTODO: Foram selecionadas vinte mulheres, entre dezoito e trinta e cinco anos, que não fizessem uso de qualquer tipo de anticoncepcional, com audição normal e sem queixas vestibulares. O exame vestibular foi realizado em cada participante no período pré e no período pós-menstrual, em ordem aleatória, e respeitando o limite de até dez dias antes do início da menstruação e até dez dias após o início da menstruação. RESULTADO: Foi observada

(Lead concentration in the blood and aminolevulinic acid dehydratase (ALAD) activity in the erythrocytes depending on sex, age, tobacco smoking and alcohol drinking in the group of persons exposed to industrial dust)

Energy Technology Data Exchange (ETDEWEB)

Kuliczkowski, K

1981-01-01

A population of 399 persons (180 women and 219 men) has been examined. Anamnesis included detailed inquiries about smoking habit and alcohol drinking. In the laboratory, lead concentration in blood and ALAD activity in erythrocytes have been determined on empty stomach. No differences have been found in the mean lead concentration determined by sex, whereas the mean ALAD activity is higher in women than in men. The subjects' age has affected the test parameters neither in men nor women. In smoking men no changes in the mean lead concentration in blood and mean ALAD activity in erythrocytes have been found. In smoking women, the mean lead concentration is not changed, but the mean ALAD activity is lower. Alcohol drinking in men does not change the values of the test parameters, whereas drinking women have revealed higher mean blood lead concentration.

Ti plasmid-encoded genes responsible for catabolism of the crown gall opine mannopine by Agrobacterium tumefaciens are homologs of the T-region genes responsible for synthesis of this opine by the plant tumor.

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Kim, K S; Farrand, S K

1996-06-01

Agrobacterium tumefaciens NT1 harboring pSaB4, which contains the 14-kb BamHI fragment 4 from the octopine/mannityl opine-type Ti plasmid pTi15955, grew well with agropine (AGR) but slowly with mannopine (MOP) as the sole carbon source. When a second plasmid encoding a dedicated transport system for MOP was introduced, these cells grew well with both AGR and MOP. Transposon insertion mutagenesis and subcloning identified a 5.7-kb region of BamHI fragment 4 that encodes functions required for the degradation of MOP. DNA sequence analysis revealed seven putative genes in this region: mocD (moc for mannityl opine catabolism) and mocE, oriented from right to left, and mocRCBAS, oriented from left to right. Significant identities exist at the nucleotide and derived amino acid sequence levels between these moc genes and the mas genes that are responsible for opine biosynthesis in crown gall tumors. MocD is a homolog of Mas2, the anabolic conjugase encoded by mas2'. MocE and MocC are related to the amino half and the carboxyl half, respectively, of Mas1 (MOP reductase), the second enzyme for MOP biosynthesis. These results indicate that the moc and mas genes evolved from a common origin. MocR and MocS are related to each other and to a putative repressor for the AGR degradation system encoded by the rhizogenic plasmid pRiA4. MocB and MocA are homologs of 6-phosphogluconate dehydratase and glucose-6-phosphate dehydrogenase, respectively. Mutations in mocD and mocE, but not mocC, are suppressed by functions encoded by the chromosome or the 450-kb megaplasmid present in many Agrobacterium isolates. We propose that moc genes derived from genes located elsewhere in the bacterial genome and that the tumor-expressed mas genes evolved from the bacterial moc genes.

Altered Levels of Aroma and Volatiles by Metabolic Engineering of Shikimate Pathway Genes in Tomato Fruits

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Vered Tzin

2015-06-01

Full Text Available The tomato (Solanum lycopersicum fruit is an excellent source of antioxidants, dietary fibers, minerals and vitamins and therefore has been referred to as a “functional food”. Ripe tomato fruits produce a large number of specialized metabolites including volatile organic compounds. These volatiles serve as key components of the tomato fruit flavor, participate in plant pathogen and herbivore defense, and are used to attract seed dispersers. A major class of specialized metabolites is derived from the shikimate pathway followed by aromatic amino acid biosynthesis of phenylalanine, tyrosine and tryptophan. We attempted to modify tomato fruit flavor by overexpressing key regulatory genes in the shikimate pathway. Bacterial genes encoding feedback-insensitive variants of 3-Deoxy-D-Arabino-Heptulosonate 7-Phosphate Synthase (DAHPS; AroG209-9 and bi-functional Chorismate Mutase/Prephenate Dehydratase (CM/PDT; PheA12 were expressed under the control of a fruit-specific promoter. We crossed these transgenes to generate tomato plants expressing both the AroG209 and PheA12 genes. Overexpression of the AroG209-9 gene had a dramatic effect on the overall metabolic profile of the fruit, including enhanced levels of multiple volatile and non-volatile metabolites. In contrast, the PheA12 overexpression line exhibited minor metabolic effects compared to the wild type fruit. Co-expression of both the AroG209-9 and PheA12 genes in tomato resulted overall in a similar metabolic effect to that of expressing only the AroG209-9 gene. However, the aroma ranking attributes of the tomato fruits from PheA12//AroG209-9 were unique and different from those of the lines expressing a single gene, suggesting a contribution of the PheA12 gene to the overall metabolic profile. We suggest that expression of bacterial genes encoding feedback-insensitive enzymes of the shikimate pathway in tomato fruits provides a useful metabolic engineering tool for the modification of

Eryptosis in lead-exposed workers

International Nuclear Information System (INIS)

Aguilar-Dorado, Itzel-Citlalli; Hernández, Gerardo; Quintanar-Escorza, Martha-Angelica; Maldonado-Vega, María; Rosas-Flores, Margarita; Calderón-Salinas, José-Víctor

2014-01-01

Eryptosis is a physiological phenomenon in which old and damaged erythrocytes are removed from circulation. Erythrocytes incubated with lead have exhibited major eryptosis. In the present work we found evidence of high levels of eryptosis in lead exposed workers possibly via oxidation. Blood samples were taken from 40 male workers exposed to lead (mean blood lead concentration 64.8 μg/dl) and non-exposed workers (4.2 μg/dl). The exposure to lead produced an intoxication characterized by 88.3% less δ-aminolevulinic acid dehydratase (δALAD) activity in lead exposed workers with respect to non-lead exposed workers. An increment of oxidation in lead exposed workers was characterized by 2.4 times higher thiobarbituric acid-reactive substance (TBARS) concentration and 32.8% lower reduced/oxidized glutathione (GSH/GSSG) ratio. Oxidative stress in erythrocytes of lead exposed workers is expressed in 192% higher free calcium concentration [Ca 2+ ] i and 1.6 times higher μ-calpain activity with respect to non-lead exposed workers. The adenosine triphosphate (ATP) concentration was not significantly different between the two worker groups. No externalization of phosphatidylserine (PS) was found in non-lead exposed workers (< 0.1%), but lead exposed workers showed 2.82% externalization. Lead intoxication induces eryptosis possibly through a molecular pathway that includes oxidation, depletion of reduced glutathione (GSH), increment of [Ca 2+ ], μ-calpain activation and externalization of PS in erythrocytes. Identifying molecular signals that induce eryptosis in lead intoxication is necessary to understand its physiopathology and chronic complications. - Graphical abstract: Fig. 1. (A) Blood lead concentration (PbB) and (B) phosphatidylserine externalization on erythrocyte membranes of non-lead exposed (□) and lead exposed workers (■). Values are mean ± SD. *Significantly different (P < 0.001). - Highlights: • Erythrocytes of lead exposed workers showed higher PS

Targeted Disruption of Melanin Biosynthesis Genes in the Human Pathogenic Fungus Lomentospora prolificans and Its Consequences for Pathogen Survival.

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Al-Laaeiby, Ayat; Kershaw, Michael J; Penn, Tina J; Thornton, Christopher R

2016-03-24

The dematiaceous (melanised) fungus Lomentospora (Scedosporium) prolificans is a life-threatening opportunistic pathogen of immunocompromised humans, resistant to anti-fungal drugs. Melanin has been shown to protect human pathogenic fungi against antifungal drugs, oxidative killing and environmental stresses. To determine the protective role of melanin in L. prolificans to oxidative killing (H₂O₂), UV radiation and the polyene anti-fungal drug amphotericin B, targeted gene disruption was used to generate mutants of the pathogen lacking the dihydroxynaphthalene (DHN)-melanin biosynthetic enzymes polyketide synthase (PKS1), tetrahydroxynapthalene reductase (4HNR) and scytalone dehydratase (SCD1). Infectious propagules (spores) of the wild-type strain 3.1 were black/brown, whereas spores of the PKS-deficient mutant ΔLppks1::hph were white. Complementation of the albino mutant ΔLppks1::hph restored the black-brown spore pigmentation, while the 4HNR-deficient mutant ΔLp4hnr::hph and SCD-deficient mutant ΔLpscd1::hph both produced orange-yellow spores. The mutants ΔLppks1::hph and ΔLp4hnr::hph showed significant reductions in spore survival following H₂O₂ treatment, while spores of ΔLpscd1::hph and the ΔLppks1::hph complemented strain ΔLppks1::hph:PKS showed spore survivals similar to strain 3.1. Spores of the mutants ΔLp4hnr::hph and ΔLpscd1::hph and complemented strain ΔLppks1::hph:PKS showed spore survivals similar to 3.1 following exposure to UV radiation, but survival of ΔLppks1::hph spores was significantly reduced compared to the wild-type strain. Strain 3.1 and mutants ΔLp4hnr::hph and ΔLppks1::hph:PKS were resistant to amphotericin B while, paradoxically, the PKS1- and SCD1-deficient mutants showed significant increases in growth in the presence of the antifungal drug. Taken together, these results show that while melanin plays a protective role in the survival of the pathogen to oxidative killing and UV radiation, melanin does not

Experimental study on the effect of ingested lead shot on Estuarine crocodiles: significance for Finniss River field studies

International Nuclear Information System (INIS)

Hammerton, K.M.

2002-01-01

Lead has long been recognised as a cumulative metabolic poison in humans, domestic animals and wildlife. Because of the many industrial activities that have brought about its widespread distribution, lead is ubiquitous in the environment. For example, uranium mining at the Rum Jungle site on the Finniss River, Northern Territory, resulted in contamination of river sediments with lead. Today, lead levels remain at about 250 mg kg-1 of wet river sediment within the immediate vicinity of the mine. Another potential source of lead poisoning in wildlife is the use of lead gunshot for hunting. Mortality in wild waterfowl caused by the ingestion of spent lead shot has been recognised in North America and Europe for over a century. An experimental study was undertaken to assess the above hypothesis on the effects of lead in the environs of crocodiles. The specific effects of lead intoxication arise mainly from the interaction of lead with the enzymatic processes in the haem biosynthetic pathway. One of these enzymes, δ-aminolevulinic acid dehydratase (ALAD), catalyses the condensation of two molecules of aminolevulinic acid to produce the pyrrole, porphobilinogen, the building block of the haem molecule. ALAD is a metalloenzyme requiring zinc for activity and is inhibited by lead displacing the essential zinc. This inhibition of ALAD by lead has been used as a specific biomarker for lead poisoning in fish, birds and mammals. An assay system was developed for the measurement of ALAD activity in crocodilian blood. It was found that ALAD was inhibited by up to 90% during the first week after exposure of the crocodiles to lead shot. There was an inverse correlation between BPb and ALAD activity throughout the 42 week experimental period. BPb concentrations greater than 100 mg dL-1 produced significant inhibition of ALAD. The results indicated that ALAD inhibition could be used as a specific biomarker of lead toxicity in crocodiles

Eryptosis in lead-exposed workers

Energy Technology Data Exchange (ETDEWEB)

Aguilar-Dorado, Itzel-Citlalli [Biochemistry Department, Centro de Investigación y Estudios Avanzados IPN, México, DF (Mexico); Hernández, Gerardo [Section of Methodology of Science, Centro de Investigación y Estudios Avanzados IPN, México, DF (Mexico); Quintanar-Escorza, Martha-Angelica [Faculty of Medicine, UJED, Durango, DGO (Mexico); Maldonado-Vega, María [CIATEC, León, GTO (Mexico); Rosas-Flores, Margarita [Biochemistry Department, Centro de Investigación y Estudios Avanzados IPN, México, DF (Mexico); Calderón-Salinas, José-Víctor, E-mail: jcalder@cinvestav.mx [Biochemistry Department, Centro de Investigación y Estudios Avanzados IPN, México, DF (Mexico)

2014-12-01

Eryptosis is a physiological phenomenon in which old and damaged erythrocytes are removed from circulation. Erythrocytes incubated with lead have exhibited major eryptosis. In the present work we found evidence of high levels of eryptosis in lead exposed workers possibly via oxidation. Blood samples were taken from 40 male workers exposed to lead (mean blood lead concentration 64.8 μg/dl) and non-exposed workers (4.2 μg/dl). The exposure to lead produced an intoxication characterized by 88.3% less δ-aminolevulinic acid dehydratase (δALAD) activity in lead exposed workers with respect to non-lead exposed workers. An increment of oxidation in lead exposed workers was characterized by 2.4 times higher thiobarbituric acid-reactive substance (TBARS) concentration and 32.8% lower reduced/oxidized glutathione (GSH/GSSG) ratio. Oxidative stress in erythrocytes of lead exposed workers is expressed in 192% higher free calcium concentration [Ca{sup 2+}]{sub i} and 1.6 times higher μ-calpain activity with respect to non-lead exposed workers. The adenosine triphosphate (ATP) concentration was not significantly different between the two worker groups. No externalization of phosphatidylserine (PS) was found in non-lead exposed workers (< 0.1%), but lead exposed workers showed 2.82% externalization. Lead intoxication induces eryptosis possibly through a molecular pathway that includes oxidation, depletion of reduced glutathione (GSH), increment of [Ca{sup 2+}], μ-calpain activation and externalization of PS in erythrocytes. Identifying molecular signals that induce eryptosis in lead intoxication is necessary to understand its physiopathology and chronic complications. - Graphical abstract: Fig. 1. (A) Blood lead concentration (PbB) and (B) phosphatidylserine externalization on erythrocyte membranes of non-lead exposed (□) and lead exposed workers (■). Values are mean ± SD. *Significantly different (P < 0.001). - Highlights: • Erythrocytes of lead exposed workers

Alcohol Selectivity in a Synthetic Thermophilic n-Butanol Pathway Is Driven by Biocatalytic and Thermostability Characteristics of Constituent Enzymes.

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Loder, Andrew J; Zeldes, Benjamin M; Garrison, G Dale; Lipscomb, Gina L; Adams, Michael W W; Kelly, Robert M

2015-10-01

n-Butanol is generated as a natural product of metabolism by several microorganisms, but almost all grow at mesophilic temperatures. A synthetic pathway for n-butanol production from acetyl coenzyme A (acetyl-CoA) that functioned at 70°C was assembled in vitro from enzymes recruited from thermophilic bacteria to inform efforts for engineering butanol production into thermophilic hosts. Recombinant versions of eight thermophilic enzymes (β-ketothiolase [Thl], 3-hydroxybutyryl-CoA dehydrogenase [Hbd], and 3-hydroxybutyryl-CoA dehydratase [Crt] from Caldanaerobacter subterraneus subsp. tengcongensis; trans-2-enoyl-CoA reductase [Ter] from Spirochaeta thermophila; bifunctional acetaldehyde dehydrogenase/alcohol dehydrogenase [AdhE] from Clostridium thermocellum; and AdhE, aldehyde dehydrogenase [Bad], and butanol dehydrogenase [Bdh] from Thermoanaerobacter sp. strain X514) were utilized to examine three possible pathways for n-butanol. These pathways differed in the two steps required to convert butyryl-CoA to n-butanol: Thl-Hbd-Crt-Ter-AdhE (C. thermocellum), Thl-Hbd-Crt-Ter-AdhE (Thermoanaerobacter X514), and Thl-Hbd-Crt-Ter-Bad-Bdh. n-Butanol was produced at 70°C, but with different amounts of ethanol as a coproduct, because of the broad substrate specificities of AdhE, Bad, and Bdh. A reaction kinetics model, validated via comparison to in vitro experiments, was used to determine relative enzyme ratios needed to maximize n-butanol production. By using large relative amounts of Thl and Hbd and small amounts of Bad and Bdh, >70% conversion to n-butanol was observed in vitro, but with a 60% decrease in the predicted pathway flux. With more-selective hypothetical versions of Bad and Bdh, >70% conversion to n-butanol is predicted, with a 19% increase in pathway flux. Thus, more-selective thermophilic versions of Bad, Bdh, and AdhE are needed to fully exploit biocatalytic n-butanol production at elevated temperatures. Copyright © 2015, American Society for

ZIP8 zinc transporter: indispensable role for both multiple-organ organogenesis and hematopoiesis in utero.

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Marina Gálvez-Peralta

Full Text Available Previously this laboratory characterized Slc39a8-encoded ZIP8 as a Zn(2+/(HCO(3(-(2 symporter; yet, the overall physiological importance of ZIP8 at the whole-organism level remains unclear. Herein we describe the phenotype of the hypomorphic Slc39a8(neo/neo mouse which has retained the neomycin-resistance gene in intron 3, hence causing significantly decreased ZIP8 mRNA and protein levels in embryo, fetus, placenta, yolk sac, and several tissues of neonates. The Slc39a8(neo allele is associated with diminished zinc and iron uptake in mouse fetal fibroblast and liver-derived cultures; consequently, Slc39a8(neo/neo newborns exhibit diminished zinc and iron levels in several tissues. Slc39a8(neo/neo homozygotes from gestational day(GD-11.5 onward are pale, growth-stunted, and die between GD18.5 and 48 h postnatally. Defects include: severely hypoplastic spleen; hypoplasia of liver, kidney, lung, and lower limbs. Histologically, Slc39a8(neo/neo neonates show decreased numbers of hematopoietic islands in yolk sac and liver. Low hemoglobin, hematocrit, red cell count, serum iron, and total iron-binding capacity confirmed severe anemia. Flow cytometry of fetal liver cells revealed the erythroid series strikingly affected in the hypomorph. Zinc-dependent 5-aminolevulinic acid dehydratase, required for heme synthesis, was not different between Slc39a8(+/+ and Slc39a8(neo/neo offspring. To demonstrate further that the mouse phenotype is due to ZIP8 deficiency, we bred Slc39a8(+/neo with BAC-transgenic BTZIP8-3 line (carrying three extra copies of the Slc39a8 allele; this cross generated viable Slc39a8(neo/neo_BTZIP8-3(+/+ pups showing none of the above-mentioned congenital defects-proving Slc39a8(neo/neo causes the described phenotype. Our study demonstrates that ZIP8-mediated zinc transport plays an unappreciated critical role during in utero and neonatal growth, organ morphogenesis, and hematopoiesis.

Effects of 1,2-dibromo-3-chloropropane on hepatic heme synthesis

International Nuclear Information System (INIS)

Moody, D.E.; Clawson, G.A.; Piper, W.N.; Smuckler, E.A.

1984-01-01

Previous studies showed that 1,2-dibromo-3-chloropropane (DBCP) caused a decrease in hepatic microsomal cytochrome P-450 suggesting that hepatic heme metabolism may be affected by DBCP treatment. Various parameters of hepatic heme synthesis were measured at intervals ranging from 0 to 72 hr in male Sprague-Dawley rats given a single oral dose (200 mg/kg) of DBCP. Incorporation of the radiolabeled heme precursor [delta-14C]aminolevulinic acid (14C-ALA) into liver, protein, extracted heme, and subcellular fractions of liver homogenates was significantly decreased to 75, 58, and 81% of controls, respectively, at 24 hr. At 48 and 72 hr after DBCP treatment, the accumulation of 14C-ALA label after 4 hr in liver homogenates and subcellular fractions was significantly increased in comparison to controls. These changes in 14C-ALA uptake were accompanied by decreases in total liver and microsomal heme, but not mitochondrial heme. Decreases were found in the spectral content of two heme proteins, cytochromes P-450 and b5, and the activity of another heme protein, catalase. Heme oxygenase activity increased to 130, 151, 209, and 186% of control values at 12, 24, 48, and 72 hr after DBCP, respectively. A slight, but significant, increase in ALA-synthetase to 112% of controls occurred at 24 hr, and slight, but significant, decreases in ALA-dehydratase to 90 and 80% of control occurred at 12 and 24 hr, respectively. No significant changes in uroporphyrinogen-1-synthetase or ferrochelatase at the time points tested was noted. The porphyrin content of liver was increased to 130% of control, while the serum and urine porphyrin levels were decreased to 30% of the control values at 24 hr. Liver ALA content was not significantly altered through the time period studied, but serum and urine levels were increased at 24 hr to 176 and 130% of the control values, respectively. In conclusion, the decreases in liver heme proteins following a single oral dose of DBCP are accompanied by

A Three-Ring Circus: Metabolism of the Three Proteogenic Aromatic Amino Acids and Their Role in the Health of Plants and Animals

Science.gov (United States)

Parthasarathy, Anutthaman; Cross, Penelope J.; Dobson, Renwick C. J.; Adams, Lily E.; Savka, Michael A.; Hudson, André O.

2018-01-01

Tyrosine, phenylalanine and tryptophan are the three aromatic amino acids (AAA) involved in protein synthesis. These amino acids and their metabolism are linked to the synthesis of a variety of secondary metabolites, a subset of which are involved in numerous anabolic pathways responsible for the synthesis of pigment compounds, plant hormones and biological polymers, to name a few. In addition, these metabolites derived from the AAA pathways mediate the transmission of nervous signals, quench reactive oxygen species in the brain, and are involved in the vast palette of animal coloration among others pathways. The AAA and metabolites derived from them also have integral roles in the health of both plants and animals. This review delineates the de novo biosynthesis of the AAA by microbes and plants, and the branching out of AAA metabolism into major secondary metabolic pathways in plants such as the phenylpropanoid pathway. Organisms that do not possess the enzymatic machinery for the de novo synthesis of AAA must obtain these primary metabolites from their diet. Therefore, the metabolism of AAA by the host animal and the resident microflora are important for the health of all animals. In addition, the AAA metabolite-mediated host-pathogen interactions in general, as well as potential beneficial and harmful AAA-derived compounds produced by gut bacteria are discussed. Apart from the AAA biosynthetic pathways in plants and microbes such as the shikimate pathway and the tryptophan pathway, this review also deals with AAA catabolism in plants, AAA degradation via the monoamine and kynurenine pathways in animals, and AAA catabolism via the 3-aryllactate and kynurenine pathways in animal-associated microbes. Emphasis will be placed on structural and functional aspects of several key AAA-related enzymes, such as shikimate synthase, chorismate mutase, anthranilate synthase, tryptophan synthase, tyrosine aminotransferase, dopachrome tautomerase, radical dehydratase, and type

Genetic metabolic complementation establishes a requirement for GDP-fucose in Leishmania.

Science.gov (United States)

Guo, Hongjie; Novozhilova, Natalia M; Bandini, Giulia; Turco, Salvatore J; Ferguson, Michael A J; Beverley, Stephen M

2017-06-23

To survive in its sand fly vector, the trypanosomatid protozoan parasite Leishmania first attaches to the midgut to avoid excretion, but eventually it must detach for transmission by the next bite. In Leishmania major strain Friedlin, this is controlled by modifications of the stage-specific adhesin lipophosphoglycan (LPG). During differentiation to infective metacyclics, d-arabinopyranose (d-Ara p ) caps the LPG side-chain galactose residues, blocking interaction with the midgut lectin PpGalec, thereby leading to parasite detachment and transmission. Previously, we characterized two closely related L. major genes ( FKP40 and AFKP80 ) encoding bifunctional proteins with kinase/pyrophosphorylase activities required for salvage and conversion of l-fucose and/or d-Ara p into the nucleotide-sugar substrates required by glycosyltransferases. Whereas only AFKP80 yielded GDP-d-Ara p from exogenous d-Ara p , both proteins were able to salvage l-fucose to GDP-fucose. We now show that Δ afkp80 - null mutants ablated d-Ara p modifications of LPG as predicted, whereas Δ fkp40 - null mutants resembled wild type (WT). Fucoconjugates had not been reported previously in L. major , but unexpectedly, we were unable to generate fkp40 - / afkp80 - double mutants, unless one of the A/FKPs was expressed ectopically. To test whether GDP-fucose itself was essential for Leishmania viability, we employed "genetic metabolite complementation." First, the trypanosome de novo pathway enzymes GDP-mannose dehydratase (GMD) and GDP-fucose synthetase (GMER) were expressed ectopically; from these cells, the Δ fkp40 - /Δ afkp80 - double mutant was now readily obtained. As expected, the Δ fkp40 - /Δ afkp80 - /+ TbGMD-GMER line lacked the capacity to generate GDP-Ara p , while synthesizing abundant GDP-fucose. These results establish a requirement for GDP-fucose for L. major viability and predict the existence of an essential fucoconjugate(s). © 2017 by The American Society for Biochemistry and

In silico analysis of the fucosylation-associated genome of the human blood fluke Schistosoma mansoni: cloning and characterization of the enzymes involved in GDP-L-fucose synthesis and Golgi import.

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Peterson, Nathan A; Anderson, Tavis K; Wu, Xiao-Jun; Yoshino, Timothy P

2013-07-09

Carbohydrate structures of surface-expressed and secreted/excreted glycoconjugates of the human blood fluke Schistosoma mansoni are key determinants that mediate host-parasite interactions in both snail and mammalian hosts. Fucose is a major constituent of these immunologically important glycans, and recent studies have sought to characterize fucosylation-associated enzymes, including the Golgi-localized fucosyltransferases that catalyze the transfer of L-fucose from a GDP-L-fucose donor to an oligosaccharide acceptor. Importantly, GDP-L-fucose is the only nucleotide-sugar donor used by fucosyltransferases and its availability represents a bottleneck in fucosyl-glycotope expression. A homology-based genome-wide bioinformatics approach was used to identify and molecularly characterize the enzymes that contribute to GDP-L-fucose synthesis and Golgi import in S. mansoni. Putative functions were further investigated through molecular phylogenetic and immunocytochemical analyses. We identified homologs of GDP-D-mannose-4,6-dehydratase (GMD) and GDP-4-keto-6-deoxy-D-mannose-3,5-epimerase-4-reductase (GMER), which constitute a de novo pathway for GDP-L-fucose synthesis, in addition to a GDP-L-fucose transporter (GFT) that putatively imports cytosolic GDP-L-fucose into the Golgi. In silico primary sequence analyses identified characteristic Rossman loop and short-chain dehydrogenase/reductase motifs in GMD and GMER as well as 10 transmembrane domains in GFT. All genes are alternatively spliced, generating variants of unknown function. Observed quantitative differences in steady-state transcript levels between miracidia and primary sporocysts may contribute to differential glycotope expression in early larval development. Additionally, analyses of protein expression suggest the occurrence of cytosolic GMD and GMER in the ciliated epidermal plates and tegument of miracidia and primary sporocysts, respectively, which is consistent with previous localization of highly

Contribution of the nos-pdt operon to virulence phenotypes in methicillin-sensitive Staphylococcus aureus.

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April M Sapp

Full Text Available Nitric oxide (NO is emerging as an important regulator of bacterial stress resistance, biofilm development, and virulence. One potential source of endogenous NO production in the pathogen Staphylococcus aureus is its NO-synthase (saNOS enzyme, encoded by the nos gene. Although a role for saNOS in oxidative stress resistance, antibiotic resistance, and virulence has been recently-described, insights into the regulation of nos expression and saNOS enzyme activity remain elusive. To this end, transcriptional analysis of the nos gene in S. aureus strain UAMS-1 was performed, which revealed that nos expression increases during low-oxygen growth and is growth-phase dependent. Furthermore, nos is co-transcribed with a downstream gene, designated pdt, which encodes a prephenate dehydratase (PDT enzyme involved in phenylalanine biosynthesis. Deletion of pdt significantly impaired the ability of UAMS-1 to grow in chemically-defined media lacking phenylalanine, confirming the function of this enzyme. Bioinformatics analysis revealed that the operon organization of nos-pdt appears to be unique to the staphylococci. As described for other S. aureus nos mutants, inactivation of nos in UAMS-1 conferred sensitivity to oxidative stress, while deletion of pdt did not affect this phenotype. The nos mutant also displayed reduced virulence in a murine sepsis infection model, and increased carotenoid pigmentation when cultured on agar plates, both previously-undescribed nos mutant phenotypes. Utilizing the fluorescent stain 4-Amino-5-Methylamino-2',7'-Difluorofluorescein (DAF-FM diacetate, decreased levels of intracellular NO/reactive nitrogen species (RNS were detected in the nos mutant on agar plates. These results reinforce the important role of saNOS in S. aureus physiology and virulence, and have identified an in vitro growth condition under which saNOS activity appears to be upregulated. However, the significance of the operon organization of nos-pdt and

Lead concentrations and reproductive success in European starlings Sturnus vulgaris nesting within highway roadside verges

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Grue, C.E.; Hoffman, D.J.; Beyer, W.N.; Franson, L.P.

1986-01-01

In 1981, the authors studied lead concentrations and reproductive success in free-living European starlings Sturnus vulgaris nesting within the verges of two Maryland highways with different traffic volumes, Route 197(average daily traffic volume[ADT] = 10,800 vehicles) and the Baltimore-Washington Parkway (ADT=52,500 vehicles) and a nearby control area. Concentrations (mg kg-1 dry weight) of lead in the ingesta (84-94 mg kg-1), carcasses (4.0-9.6 mg kg-1)and feathers (6.8-52 mg kg-1) of Parkway nestlings and adults were 3 to 13 times those found in starlings from the control area, whereas lead concentrations in the ingesta and tissues of starlings from the verge of Route 197 were similar to those of controls. Activity of delta-aminolevulinic acid dehydratase (ALAD) in red blood cells (RBCs) of adult and nestling starlings from the Parkway was depressed from 43 to 60% compared to controls. RBC ALAD activity in adults from nests along Route 197 was similar to that of adult starlings from the control area, but that of their young was depressed 17%. Haemoglobin concentrations (-16%) and haematocrits (-10%) in Parkway nestlings were depressed compared with those of nestlings from the other two study areas, whereas those of adults were not affected. Clutch size, number of young hatched and the number of young in nests 1 to 3 days before fledging were similar among sites, as were body weights of adults and prefledging weights of their young. However, brain weights of Parkway nestlings were lower (P < 0.05) than those of nestlings from the other study areas. Results suggests that lead within verges of major highways probably does not pose a serious hazard to adult ground-foraging songbirds. However, the effects of lead-induced reductions in haemoglobin concentration, haematocrit, RBC ALAD activity and brain weight on the postfledging survival of their young are not known.

Toxicity of lead-contaminated sediment to mute swans

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Day, D.D.; Beyer, W.N.; Hoffman, D.J.; Morton, Alexandra; Sileo, L.; Audet, D.J.; Ottinger, M.A.

2003-01-01

Most ecotoxicological risk assessments of wildlife emphasize contaminant exposure through ingestion of food and water. However, the role of incidental ingestion of sediment-bound contaminants has not been adequately appreciated in these assessments. This study evaluates the toxicological consequences of contamination of sediments with metals from hard-rock mining and smelting activities. Lead-contaminated sediments collected from the Coeur d'Alene River Basin in Idaho were combined with either a commercial avian maintenance diet or ground rice and fed to captive mute swans (Cygnus olor) for 6 weeks. Experimental treatments consisted of maintenance or rice diets containing 0, 12 (no rice group), or 24% highly contaminated (3,950 ug/g lead) sediment or 24% reference (9.7 ug/g lead) sediment. Although none of the swans died, the group fed a rice diet containing 24% lead-contaminated sediment were the most severely affected, experiencing a 24% decrease in mean body weight, including three birds that became emaciated. All birds in this treatment group had nephrosis; abnormally dark, viscous bile; and significant (p < 0.05) reductions in hematocrit and hemoglobin concentrations compared to their pretreatment levels. This group also had the greatest mean concentrations of lead in blood (3.2 ug/g), brain (2.2 ug/g), and liver (8.5 ug/g). These birds had significant (alpha = 0.05) increases in mean plasma alanine aminotransferase activity, cholesterol, and uric acid concentrations and decreased plasma triglyceride concentrations compared to all other treatment groups. After 14 days of exposure, mean protoporphyrin concentrations increased substantially, and mean delta-aminolevulinic acid dehydratase activity decreased by more than 95% in all groups fed diets containing highly contaminated sediments. All swans fed diets that contained 24% lead-contaminated sediment had renal acid-fast intranuclear inclusion bodies, which are diagnostic of lead poisoning in waterfowl. Body

Quantitative partition of threonine oxidation in pigs: Effect of dietary threonine

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Ballevre, O.; Cadenhead, A.; Calder, A.G.; Rees, W.D.; Lobley, G.E.; Fuller, M.F.; Garlick, P.J.

1990-01-01

Kinetic aspects of threonine (Thr) metabolism were examined in eight pigs fed hourly with a diet containing either 0.68% (LT group) or 0.81% (HT group) of Thr (wt/wt), corresponding to 10 and 30% Thr excess, respectively, compared with an ideal diet. Primary production (PR) and disposal (DR) rates were obtained for Thr, glycine (Gly), and 2-keto-butyrate (KB) after a 12-h continuous infusion of L-[U-14C]-Thr together with [1-13C]Gly and a 6-h continuous infusion of [1-14C]KB. Transfer of Thr into secondary pools was also monitored, and from these the rates of Thr oxidation through the catabolic pathways of L-Thr 3-dehydrogenase (DR(Thr-Gly)) and threonine dehydratase (DR(Thr-KB)) were estimated. For the LT group the results were (mumol.kg-1.h-1) PR(Thr) 314 +/- 3, PR(Gly) 551 +/- 24, PR(KB) 41 +/- 3, DR(Thr-Gly) 22 +/- 2, and DR(Thr-KB) 7 +/- 1. For the HT group they were PR(Thr) 301 +/- 23, PR(Gly) 598 +/- 55, PR(KB) 39 +/- 4, DR(Thr-Gly) 32 +/- 2, and DR(Thr-KB) 8 +/- 1. The increase in Thr intake (14 mumol.kg-1.h-1, P less than 0.01) induced a commensurate increase in the sum of DR(Thr-Gly) and DR(Thr-KB) (14 mumol.kg-1.h-1, P less than 0.001) when liver was used as the precursor pool. This was mainly due to the increased DR(Thr-Gly) (13 mumol.kg-1.h-1, P less than 0.01); the change in DR(Thr-KB) was not statistically significant. By comparison of intracellular-to-plasma ratios of specific activities (or enrichments) for different tissues with each type of infusion, liver was shown to be the major site of production of Gly and KB from Thr. These data suggest that in fed growing pigs a 30% excess of Thr in the diet does not alter the partition of Thr oxidation, since 80% of Thr oxidation occurs through the L-Thr 3-dehydrogenase pathway for both LT and HT groups

The Bone Building Blues: Self-hardening copper-doped calcium phosphate cement and its in vitro assessment against mammalian cells and bacteria.

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Rau, Julietta V; Wu, Victoria M; Graziani, Valerio; Fadeeva, Inna V; Fomin, Alexander S; Fosca, Marco; Uskoković, Vuk

2017-10-01

-free cements. The difference in the mechanism of protection of dehydratases in prokaryotes and eukaryotes was used as a rationale for explaining the hereby evidenced selectivity in biological response. It presents the basis for the consideration of copper as a dually effective ion when synergized with calcium phosphates: toxic for bacteria and beneficial for the healthy cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Ground squirrel shooting and potential lead exposure in breeding avian scavengers

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Herring, Garth; Eagles-Smith, Collin A.; Wagner, Mason T.

2016-01-01

, and diet, 100% of the nestling period would exceed a 50% reduction in delta-aminolevulinic acid dehydratase production threshold, the last 13–27% of the nestling stage would exceed a reduced growth rate threshold, but no nestlings would be expected to exceed a level of Pb ingestion that would be lethal.

Ground Squirrel Shooting and Potential Lead Exposure in Breeding Avian Scavengers.

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Garth Herring

needs, and diet, 100% of the nestling period would exceed a 50% reduction in delta-aminolevulinic acid dehydratase production threshold, the last 13-27% of the nestling stage would exceed a reduced growth rate threshold, but no nestlings would be expected to exceed a level of Pb ingestion that would be lethal.

Combined Administration of Taurine and Monoisoamyl Dmsa Protects Arsenic Induced Oxidative Injury in Rats

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Swaran J. S. Flora

2008-01-01

Full Text Available Arsenic is a naturally occurring element that is ubiquitously present in the environment. High concentration of naturally occurring arsenic in drinking water is a major health problem in different parts of the world. Despite arsenic being a health hazard and a well documented carcinogen, no safe, effective and specific preventive or therapeutic measures are available. Among various recent strategies adopted, administration of an antioxidant has been reported to be the most effective. The present study was designed to evaluate the therapeutic efficacy of monoisoamyl dimercaptosuccinic acid (MiADMSA, administered either individually or in combination with taurine post chronic arsenic exposure in rats. Arsenic exposed male rats (25 ppm, sodium arsenite in drinking water for 24 weeks were treated with taurine (100 mg/kg, i.p., once daily, monoisoamyl dimercaptosuccinic acid (MiADMSA (50 mg/kg, oral, once daily either individually or in combination for 5 consecutive days. Biochemical variables indicative of oxidative stress along-with arsenic concentration in blood, liver and kidney were measured. Arsenic exposure significantly reduced blood δ-aminolevulinic acid dehydratase (ALAD activity, a key enzyme involved in the heme biosynthesis and enhanced zinc protoporphyrin (ZPP level. Clinical hematological variables like white blood cells (WBC, mean cell hemoglobin (MCH, and mean cell hemoglobin concentration (MCHC showed significant decrease with a significant elevation in platelet (PLT count. These changes were accompanied by significant decrease in superoxide dismutase (SOD activity and increased catalase activity. Arsenic exposure caused a significant decrease in hepatic and renal glutathione (GSH level and an increase in oxidized glutathione (GSSG. These biochemical changes were correlated with an increased uptake of arsenic in blood, liver and kidney. Administration of taurine significantly reduced hepatic oxidative stress however co

Targeted Disruption of Melanin Biosynthesis Genes in the Human Pathogenic Fungus Lomentospora prolificans and Its Consequences for Pathogen Survival

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Ayat Al-Laaeiby

2016-03-01

Full Text Available The dematiaceous (melanised fungus Lomentospora (Scedosporium prolificans is a life-threatening opportunistic pathogen of immunocompromised humans, resistant to anti-fungal drugs. Melanin has been shown to protect human pathogenic fungi against antifungal drugs, oxidative killing and environmental stresses. To determine the protective role of melanin in L. prolificans to oxidative killing (H2O2, UV radiation and the polyene anti-fungal drug amphotericin B, targeted gene disruption was used to generate mutants of the pathogen lacking the dihydroxynaphthalene (DHN-melanin biosynthetic enzymes polyketide synthase (PKS1, tetrahydroxynapthalene reductase (4HNR and scytalone dehydratase (SCD1. Infectious propagules (spores of the wild-type strain 3.1 were black/brown, whereas spores of the PKS-deficient mutant ΔLppks1::hph were white. Complementation of the albino mutant ΔLppks1::hph restored the black-brown spore pigmentation, while the 4HNR-deficient mutant ΔLp4hnr::hph and SCD-deficient mutant ΔLpscd1::hph both produced orange-yellow spores. The mutants ΔLppks1::hph and ΔLp4hnr::hph showed significant reductions in spore survival following H2O2 treatment, while spores of ΔLpscd1::hph and the ΔLppks1::hph complemented strain ΔLppks1::hph:PKS showed spore survivals similar to strain 3.1. Spores of the mutants ΔLp4hnr::hph and ΔLpscd1::hph and complemented strain ΔLppks1::hph:PKS showed spore survivals similar to 3.1 following exposure to UV radiation, but survival of ΔLppks1::hph spores was significantly reduced compared to the wild-type strain. Strain 3.1 and mutants ΔLp4hnr::hph and ΔLppks1::hph:PKS were resistant to amphotericin B while, paradoxically, the PKS1- and SCD1-deficient mutants showed significant increases in growth in the presence of the antifungal drug. Taken together, these results show that while melanin plays a protective role in the survival of the pathogen to oxidative killing and UV radiation, melanin does not

CRISPR-Cas Defense System and Potential Prophages in Cyanobacteria Associated with the Coral Black Band Disease.

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Buerger, Patrick; Wood-Charlson, Elisha M; Weynberg, Karen D; Willis, Bette L; van Oppen, Madeleine J H

2016-01-01

Understanding how pathogens maintain their virulence is critical to developing tools to mitigate disease in animal populations. We sequenced and assembled the first draft genome of Roseofilum reptotaenium AO1, the dominant cyanobacterium underlying pathogenicity of the virulent coral black band disease (BBD), and analyzed parts of the BBD-associated Geitlerinema sp. BBD_1991 genome in silico . Both cyanobacteria are equipped with an adaptive, heritable clustered regularly interspaced short palindromic repeats (CRISPR)-Cas defense system type I-D and have potential virulence genes located within several prophage regions. The defense system helps to prevent infection by viruses and mobile genetic elements via identification of short fingerprints of the intruding DNA, which are stored as templates in the bacterial genome, in so-called "CRISPRs." Analysis of CRISPR target sequences (protospacers) revealed an unusually high number of self-targeting spacers in R. reptotaenium AO1 and extraordinary long CRIPSR arrays of up to 260 spacers in Geitlerinema sp. BBD_1991. The self-targeting spacers are unlikely to be a form of autoimmunity; instead these target an incomplete lysogenic bacteriophage. Lysogenic virus induction experiments with mitomycin C and UV light did not reveal an actively replicating virus population in R. reptotaenium AO1 cultures, suggesting that phage functionality is compromised or excision could be blocked by the CRISPR-Cas system. Potential prophages were identified in three regions of R. reptotaenium AO1 and five regions of Geitlerinema sp. BBD_1991, containing putative BBD relevant virulence genes, such as an NAD-dependent epimerase/dehydratase (a homolog in terms of functionality to the third and fourth most expressed gene in BBD), lysozyme/metalloendopeptidases and other lipopolysaccharide modification genes. To date, viruses have not been considered to be a component of the BBD consortium or a contributor to the virulence of R. reptotaenium AO1

Biochemical effects of lead, zinc, and cadmium from mining on fish in the Tri-States district of northeastern Oklahoma, USA

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Schmitt, Christopher J.; Whyte, Jeffrey J.; Brumbaugh, William G.; Tillitt, Donald E.

2005-01-01

We assessed the exposure of fish from the Spring and Neosho Rivers in northeast Oklahoma, USA, to lead, zinc, and cadmium from historical mining in the Tri-States Mining District (TSMD). Fish (n = 74) representing six species were collected in October 2001 from six sites on the Spring and Neosho Rivers influenced to differing degrees by mining. Additional samples were obtained from the Big River, a heavily contaminated stream in eastern Missouri, USA, and from reference sites. Blood from each fish was analyzed for Pb, Zn, Cd, Fe, and hemoglobin (Hb). Blood also was analyzed for ??-aminolevulinic acid dehydratase (ALA-D) activity. The activity of ALA-D, an enzyme involved in heme synthesis, is inhibited by Pb. Concentrations of Fe and Hb were highly correlated (r = 0.89, p < 0.01) across all species and locations and typically were greater in common carp (Cyprinus carpio) than in other taxa. Concentrations of Pb, Zn, and Cd typically were greatest in fish from sites most heavily affected by mining and lowest in reference samples. The activity of ALA-D, but not concentrations of Hb or Fe, also differed significantly (p < 0.01) among sites and species. Enzyme activity was lowest in fish from mining-contaminated sites and greatest in reference fish, and was correlated negatively with Pb in most species. Statistically significant (p < 0.01) linear regression models that included negative terms for blood Pb explained as much as 68% of the total variation in ALA-D activity, but differences among taxa were highly evident. Positive correlations with Zn were documented in the combined data for channel catfish (Ictalurus punctatus) and flathead catfish (Pylodictis olivaris), as has been reported for other taxa, but not in bass (Micropterus spp.) or carp. In channel catfish, ALA-D activity appeared to be more sensitive to blood Pb than in the other species investigated (i.e., threshold concentrations for inhibition were lower). Such among-species differences are consistent

RNA-seq reveals transcriptome changes in goats following myostatin gene knockout

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Cai, Bei; Zhou, Shiwei; Zhu, Haijing; Qu, Lei; Wang, Xiaolong

2017-01-01

Myostatin (MSTN) is a powerful negative regulator of skeletal muscle mass in mammalian species that is primarily expressed in skeletal muscles, and mutations of its encoding gene can result in the double-muscling trait. In this study, the CRISPR/Cas9 technique was used to edit MSTN in Shaanbei Cashmere goats and generate knockout animals. RNA sequencing was used to determine and compare the transcriptome profiles of the muscles from three wild-type (WT) goats, three fibroblast growth factor 5 (FGF5) knockout goats (FGF5+/- group) and three goats with disrupted expression of both the FGF5 and MSTN genes (FM+/- group). The sequence reads were obtained using the Illumina HiSeq 2000 system and mapped to the Capra hircus reference genome using TopHat (v2.0.9). In total, 68.93, 62.04 and 66.26 million clean sequencing reads were obtained from the WT, FM+/- and FGF5+/- groups, respectively. There were 201 differentially expressed genes (DEGs) between the WT and FGF5+/- groups, with 86 down- and 115 up-regulated genes in the FGF5+/- group. Between the WT and FM+/- groups, 121 DEGs were identified, including 81 down- and 40 up-regulated genes in the FM+/- group. A total of 198 DEGs were detected between the FGF5+/- group and FM+/- group, with 128 down- and 70 up-regulated genes in the FM+/- group. At the transcriptome level, we found substantial changes in genes involved in fatty acid metabolism and the biosynthesis of unsaturated fatty acids, such as stearoyl-CoA dehydrogenase, 3-hydroxyacyl-CoA dehydratase 2, ELOVL fatty acid elongase 6 and fatty acid synthase, suggesting that the expression levels of these genes may be directly regulated by MSTN and that these genes are likely downstream targets of MSTN with potential roles in lipid metabolism in goats. Moreover, five randomly selected DEGs were further validated with qRT-PCR, and the results were consistent with the transcriptome analysis. The present study provides insight into the unique transcriptome profile of the

Effect of low blood lead levels on anaemia indicators and creatinine clearance rate of workers occupationally exposed to lead

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Memon, F.; Vasandani, A.G.M.

2009-01-01

Although recognized and written about centuries, lead toxicity remains an occupational and public health problem of global dimensions. Several studies have demonstrated that clinical and sub clinical effects of lead toxicity at the blood lead levels considered as safe, i.e., below 30 mug/dl in adults and 10 mu g/dl in children. Such studies have received scant attention in the case of lead occupational workers due to the presumption of high blood lead levels in accordance with occupation. In the present study, therefore an attempt was made to investigate the effect of low blood lead levels on indicators of anaemia and renal impairment. A cohort of 690 subjects who had been occupationally exposed to lead was studied using stratified random sampling design. The markers of anaemia included changes in Haematocrit value, Haemoglobin and Erythrocyte count where as renal health was judged from changes in creatinine clearance rate. The controls were derived from similar socioeconomic background and matched in age and sex with subjects. Blood lead levels were determined by graphite furnace atomic absorption and biochemical determinations carried out using standard procedures. Blood lead levels in the range 10-40 mu g/dl had significant effect on anaemia indicators and resulted in inverse co relationship. (Pearson's correlation coefficient r-0.65, -0.71 and -0.58 respectively for haematocrit, erythrocyte count and haemoglobin). The creatinine clearance rate estimated after adjustment for body mass index and age factors was found to depend on blood lead level and duration of exposure of subjects. These effects were statistically significant in the subjects having age in the range 15-30 years. Low lead levels in blood have high potential of inducing lead related anaemia by disturbing the pathway of heme synthesis at either ferrochetalase stage or inhibiting the amino levulinate dehydratase activity. Though creatinine clearance rate did not prove as reliable marker of renal

Evolution of Enzymatic Activities in the Enolase Superfamily: D-Mannonate Dhydratase from Novosphingobium aromaticivorans

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Rakus,J.; Fedorov, A.; Fedorov, E.; Glasner, M.; Vick, J.; Babbitt, P.; Almo, S.; Gerlt, J.

2007-01-01

The d-mannonate dehydratase (ManD) function was assigned to a group of orthologous proteins in the mechanistically diverse enolase superfamily by screening a library of acid sugars. Structures of the wild type ManD from Novosphingobium aromaticivorans were determined at pH 7.5 in the presence of Mg2+ and also in the presence of Mg2+ and the 2-keto-3-keto-d-gluconate dehydration product; the structure of the catalytically active K271E mutant was determined at pH 5.5 in the presence of the d-mannonate substrate. As previously observed in the structures of other members of the enolase superfamily, ManD contains two domains, an N-terminal a+{beta} capping domain and a ({beta}/a)7{beta}-barrel domain. The barrel domain contains the ligands for the essential Mg2+, Asp 210, Glu 236, and Glu 262, at the ends of the third, fourth, and fifth {beta}-strands of the barrel domain, respectively. However, the barrel domain lacks both the Lys acid/base catalyst at the end of the second {beta}-strand and the His-Asp dyad acid/base catalyst at the ends of the seventh and sixth {beta}-strands, respectively, that are found in many members of the superfamily. Instead, a hydrogen-bonded dyad of Tyr 159 in a loop following the second {beta}-strand and Arg 147 at the end of the second {beta}-strand are positioned to initiate the reaction by abstraction of the 2-proton. Both Tyr 159 and His 212, at the end of the third {beta}-strand, are positioned to facilitate both syn-dehydration and ketonization of the resulting enol intermediate to yield the 2-keto-3-keto-d-gluconate product with the observed retention of configuration. The identities and locations of these acid/base catalysts as well as of cationic amino acid residues that stabilize the enolate anion intermediate define a new structural strategy for catalysis (subgroup) in the mechanistically diverse enolase superfamily. With these differences, we provide additional evidence that the ligands for the essential Mg2+ are the only

Bacterial variations on the methionine salvage pathway

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Haas Dieter

2004-03-01

Full Text Available Abstract Background The thiomethyl group of S-adenosylmethionine is often recycled as methionine from methylthioadenosine. The corresponding pathway has been unravelled in Bacillus subtilis. However methylthioadenosine is subjected to alternative degradative pathways depending on the organism. Results This work uses genome in silico analysis to propose methionine salvage pathways for Klebsiella pneumoniae, Leptospira interrogans, Thermoanaerobacter tengcongensis and Xylella fastidiosa. Experiments performed with mutants of B. subtilis and Pseudomonas aeruginosa substantiate the hypotheses proposed. The enzymes that catalyze the reactions are recruited from a variety of origins. The first, ubiquitous, enzyme of the pathway, MtnA (methylthioribose-1-phosphate isomerase, belongs to a family of proteins related to eukaryotic intiation factor 2B alpha. mtnB codes for a methylthioribulose-1-phosphate dehydratase. Two reactions follow, that of an enolase and that of a phosphatase. While in B. subtilis this is performed by two distinct polypeptides, in the other organisms analyzed here an enolase-phosphatase yields 1,2-dihydroxy-3-keto-5-methylthiopentene. In the presence of dioxygen an aci-reductone dioxygenase yields the immediate precursor of methionine, ketomethylthiobutyrate. Under some conditions this enzyme produces carbon monoxide in B. subtilis, suggesting a route for a new gaseous mediator in bacteria. Ketomethylthiobutyrate is finally transaminated by an aminotransferase that exists usually as a broad specificity enzyme (often able to transaminate aromatic aminoacid keto-acid precursors or histidinol-phosphate. Conclusion A functional methionine salvage pathway was experimentally demonstrated, for the first time, in P. aeruginosa. Apparently, methionine salvage pathways are frequent in Bacteria (and in Eukarya, with recruitment of different polypeptides to perform the needed reactions (an ancestor of a translation initiation factor and Ru

The Common Gut Microbe Eubacterium hallii also Contributes to Intestinal Propionate Formation.

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Engels, Christina; Ruscheweyh, Hans-Joachim; Beerenwinkel, Niko; Lacroix, Christophe; Schwab, Clarissa

2016-01-01

Eubacterium hallii is considered an important microbe in regard to intestinal metabolic balance due to its ability to utilize glucose and the fermentation intermediates acetate and lactate, to form butyrate and hydrogen. Recently, we observed that E. hallii is capable of metabolizing glycerol to 3-hydroxypropionaldehyde (3-HPA, reuterin) with reported antimicrobial properties. The key enzyme for glycerol to 3-HPA conversion is the cobalamin-dependent glycerol/diol dehydratase PduCDE which also utilizes 1,2-propanediol (1,2-PD) to form propionate. Therefore our primary goal was to investigate glycerol to 3-HPA metabolism and 1,2-PD utilization by E. hallii along with its ability to produce cobalamin. We also investigated the relative abundance of E. hallii in stool of adults using 16S rRNA and pduCDE based gene screening to determine the contribution of E. hallii to intestinal propionate formation. We found that E. hallii utilizes glycerol to produce up to 9 mM 3-HPA but did not further metabolize 3-HPA to 1,3-propanediol. Utilization of 1,2-PD in the presence and absence of glucose led to the formation of propanal, propanol and propionate. E. hallii formed cobalamin and was detected in stool of 74% of adults using 16S rRNA gene as marker gene (n = 325). Relative abundance of the E. hallii 16S rRNA gene ranged from 0 to 0.59% with a mean relative abundance of 0.044%. E. hallii PduCDE was detected in 63 to 81% of the metagenomes depending on which subunit was investigated beside other taxons such as Ruminococcus obeum, R. gnavus, Flavonifractor plautii, Intestinimonas butyriciproducens, and Veillonella spp. In conclusion, we identified E. hallii as a common gut microbe with the ability to convert glycerol to 3-HPA, a step that requires the production of cobalamin, and to utilize 1,2-PD to form propionate. Our results along with its ability to use a broad range of substrates point at E. hallii as a key species within the intestinal trophic chain with the potential to

The common gut microbe Eubacterium hallii also contributes to intestinal propionate formation

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Christina eEngels

2016-05-01

Full Text Available Eubacterium hallii is considered an important microbe in regard to intestinal metabolic balance due to its ability to utilize glucose and the fermentation intermediates acetate and lactate, to form butyrate and hydrogen. Recently, we observed that E. hallii is capable of metabolizing glycerol to 3-hydroxypropionaldehyde (3-HPA, reuterin with reported antimicrobial properties. The key enzyme for glycerol to 3-HPA conversion is the cobalamin-dependent glycerol/diol dehydratase PduCDE which also utilizes 1,2-propanediol (1,2-PD to form propionate. Therefore our primary goal was to investigate glycerol to 3-HPA metabolism and 1,2-PD utilization by E. hallii along with its ability to produce cobalamin. We also investigated the relative abundance of E. hallii in stool of adults using 16S rRNA and pduCDE based gene screening to determine the contribution of E. hallii to intestinal propionate formation. We found that E. hallii utilizes glycerol to produce up to 9 mM 3-HPA but did not further metabolize 3-HPA to 1,3-propanediol (1,3-PD. Utilization of 1,2-PD in the presence and absence of glucose led to the formation of propanal, propanol and propionate. E. hallii formed cobalamin and was detected in stool of 74% of adults using 16S rRNA gene as marker gene (n = 325. Relative abundance of the E. hallii 16S rRNA gene ranged from 0 to 0.59% with a mean relative abundance of 0.044%. E. hallii PduCDE was detected in 63 to 81% of the metagenomes depending on which subunit was investigated beside other taxons such as Ruminococcus obeum, Ruminococcus gnavus, Flavonifractor prautii, Intestinimonas butyriciproducens, and Veillonella spp. In conclusion, we identified E. hallii as a common gut microbe with the ability to convert glycerol to 3-HPA, a step that requires the production of cobalamin, and to utilize 1,2-PD to form propionate. Our results along with its ability to use a broad range of substrates point at E. hallii as a key species within the intestinal

The heme biosynthetic pathway of the obligate Wolbachia endosymbiont of Brugia malayi as a potential anti-filarial drug target.

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Bo Wu

2009-07-01

'-aminolevulinic acid dehydratase (ALAD, the second step. Similarly, Escherichia coli hemH (FC deficient strains transformed with human and Wolbachia FC homologues showed significantly different sensitivities to NMMP. This approach enables functional complementation in E. coli heme deficient mutants as an alternative E. coli-based method for drug screening.Our studies indicate that the heme biosynthetic genes in the Wolbachia of B. malayi (wBm might be essential for the filarial host survival. In addition, the results suggest they are likely candidate drug targets based upon significant differences in phylogenetic distance, biochemical properties and sensitivities to heme biosynthesis inhibitors, as compared to their human homologues.

[Evaluation of initial results of treatment of lead poisoning with EDTA].

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Petkova, V; Adjarov, D; Pavlova, S; Naydenova, E; Kerimova, M; Kuneva, T

1994-01-01

The results of EDTA therapy were studied in 37 workers of a battery factory consisting of males with varying degrees of occupational lead poisoning (low exposure: 10 subjects, blood lead levels (PbB) lower than 400 micrograms/l with slight alterations in heme biosynthesis; beyond limit of effect: 5 subjects, PbB > 400 micrograms/l; slight intoxication: 19 subjects, with marked alterations in heme synthesis and preclinical signs of intoxication; average degree of intoxication: 3 subjects with clinical signs of intoxication. Clinical symptoms and the following parameters were investigated: blood lead (PbB), delta-aminolevulinic acid dehydratase in erythrocytes (ALA-D), zinc protoporphyrin (PP) in erythrocytes and delta-aminolevulinic acid (ALA) in 24-hour urine before and after EDTA chelating therapy. Simultaneous measurement of ALA-D and PP showed high diagnostic sensitivity in detecting lead poisoning in occupationally exposed subjects. In view of the high interindividual variability of the results, these indices did not, however, permit a useful differentiation to be made of the different degrees of intoxication at individual level, even though a good correlation was observed between PbB and porphyrin metabolism indices. From the alterations observed in ALA-D and PP values it was not possible to establish an association between degree of alteration and types of clinical symptoms in the different intoxication studies. At the end of EDTA treatment, a clinical improvement was observed in all cases studied but only in 5 cases was a reduction in PbB observed, to levels below 1.20 mol/l, which is accepted as a permissible limit for the general population; in 17 cases PbB remained at levels above the critical value for occupational lead poisoning (400 micrograms/l), although there was a decrease after treatment. The improvement observed in the indices of porphyrin metabolism at the end of treatment was only slight: significant variations were measured only for PbB. After

Modeling holo-ACP:DH and holo-ACP:KR complexes of modular polyketide synthases: a docking and molecular dynamics study

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Anand Swadha

2012-05-01

Full Text Available Abstract Background Modular polyketide synthases are multifunctional megasynthases which biosynthesize a variety of secondary metabolites using various combinations of dehydratase (DH, ketoreductase (KR and enoyl-reductase (ER domains. During the catalysis of various reductive steps these domains act on a substrate moiety which is covalently attached to the phosphopantetheine (P-pant group of the holo-Acyl Carrier Protein (holo-ACP domain, thus necessitating the formation of holo-ACP:DH and holo-ACP:KR complexes. Even though three dimensional structures are available for DH, KR and ACP domains, no structures are available for DH or KR domains in complex with ACP or substrate moieties. Since Ser of holo-ACP is covalently attached to a large phosphopantetheine group, obtaining complexes involving holo-ACP by standard protein-protein docking has been a difficult task. Results We have modeled the holo-ACP:DH and holo-ACP:KR complexes for identifying specific residues on DH and KR domains which are involved in interaction with ACP, phosphopantetheine and substrate moiety. A novel combination of protein-protein and protein-ligand docking has been used to first model complexes involving apo-ACP and then dock the phosphopantetheine and substrate moieties using covalent connectivity between ACP, phosphopantetheine and substrate moiety as constraints. The holo-ACP:DH and holo-ACP:KR complexes obtained from docking have been further refined by restraint free explicit solvent MD simulations to incorporate effects of ligand and receptor flexibilities. The results from 50 ns MD simulations reveal that substrate enters into a deep tunnel in DH domain while in case of KR domain the substrate binds a shallow surface exposed cavity. Interestingly, in case of DH domain the predicted binding site overlapped with the binding site in the inhibitor bound crystal structure of FabZ, the DH domain from E.Coli FAS. In case of KR domain, the substrate binding site

Identification and characterization of a novel zebrafish (Danio rerio pentraxin–carbonic anhydrase

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Maarit S. Patrikainen

2017-12-01

Full Text Available Background Carbonic anhydrases (CAs are ubiquitous, essential enzymes which catalyze the conversion of carbon dioxide and water to bicarbonate and H+ ions. Vertebrate genomes generally contain gene loci for 15–21 different CA isoforms, three of which are enzymatically inactive. CA VI is the only secretory protein of the enzymatically active isoforms. We discovered that non-mammalian CA VI contains a C-terminal pentraxin (PTX domain, a novel combination for both CAs and PTXs. Methods We isolated and sequenced zebrafish (Danio rerio CA VI cDNA, complete with the sequence coding for the PTX domain, and produced the recombinant CA VI–PTX protein. Enzymatic activity and kinetic parameters were measured with a stopped-flow instrument. Mass spectrometry, analytical gel filtration and dynamic light scattering were used for biophysical characterization. Sequence analyses and Bayesian phylogenetics were used in generating hypotheses of protein structure and CA VI gene evolution. A CA VI–PTX antiserum was produced, and the expression of CA VI protein was studied by immunohistochemistry. A knock-down zebrafish model was constructed, and larvae were observed up to five days post-fertilization (dpf. The expression of ca6 mRNA was quantitated by qRT-PCR in different developmental times in morphant and wild-type larvae and in different adult fish tissues. Finally, the swimming behavior of the morphant fish was compared to that of wild-type fish. Results The recombinant enzyme has a very high carbonate dehydratase activity. Sequencing confirms a 530-residue protein identical to one of the predicted proteins in the Ensembl database (ensembl.org. The protein is pentameric in solution, as studied by gel filtration and light scattering, presumably joined by the PTX domains. Mass spectrometry confirms the predicted signal peptide cleavage and disulfides, and N-glycosylation in two of the four observed glycosylation motifs. Molecular modeling of the pentamer is

Biosynthesis of Tropolones in Streptomyces spp: Interweaving Biosynthesis and Degradation of Phenylacetic Acid and Hydroxylations on Tropone Ring.

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Chen, Xuefei; Xu, Min; Lü, Jin; Xu, Jianguo; Wang, Yemin; Lin, Shuangjun; Deng, Zixin; Tao, Meifeng

2018-04-13

Tropolonoids are important natural products that contain a unique seven-membered aromatic tropolone core and exhibit remarkable biological activities. 3,7-Dihydroxytropolone (DHT) isolated from Streptomyces species is a multiply hydroxylated tropolone exhibiting antimicrobial, anticancer, and antiviral activities. Herein, we determined the DHT biosynthetic pathway by heterologous expression, gene deletion, and bioconversion. Nine trl genes and some of the aerobic phenylacetic acid degradation pathway genes ( paa ) located outside of the trl biosynthetic gene cluster are required for the heterologous production of DHT. The trlA gene encodes a single-domain protein homologous to the C-terminal enoyl-CoA hydratase domain of PaaZ. TrlA truncates the phenylacetic acid catabolic pathway and redirects it towards the formation of heptacyclic intermediates. TrlB is a 3-deoxy-D-arabino-heptulosonic acid-7-phosphate (DAHP) synthase homolog. TrlH is an unusual bifunctional protein bearing an N-terminal prephenate dehydratase domain and a C-terminal chorismate mutase domain. TrlB and TrlH enhanced de novo biosynthesis of phenylpyruvate, thereby providing abundant precursor for the prolific production of DHT in Streptomyces Six seven-membered carbocyclic compounds were identified from the gene deletion mutants of trlC , trlD , trlE , and trlF Four of these chemicals, including 1,4,6-cycloheptatriene-1-carboxylic acid, tropone, tropolone and 7-hydroxytropolone, were verified as key biosynthetic intermediates. TrlF is required for the conversion of 1,4,6-cycloheptatriene-1-carboxylic acid into tropone. Monooxygenases TrlE and TrlCD catalyze the regioselective hydroxylations of tropone to afford DHT. This study reveals a natural association of anabolism of chorismate and phenylpyruvate, catabolism of phenylacetic acid, and biosynthesis of tropolones in Streptomyces spp. IMPORTANCE Tropolonoids are promising drug lead compounds because of their versatile bioactivities attributed to

Effect of Lead (Pb Exposure on the Activity of Superoxide Dismutase and Catalase in Battery Manufacturing Workers (BMW of Western Maharashtra (India with Reference to Heme biosynthesis

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Kusal K. Das

2006-12-01

Full Text Available The aim of this study was to estimate the activity of superoxide dismutase (SOD and catalase in erythrocytes and malondialdehyde (MDA in plasma of battery manufacturing workers (BMW of Western Maharashtra (India who were occupationally exposed to lead (Pb over a long period of time (about 15 years. This study was also aimed to determine the Pb intoxication resulted in a disturbance of heme biosynthesis in BMW group. The blood Pb level of BMW group (n = 28 was found to be in the range of 25.8 – 78.0 μg/dL (mean + SD, 53.63 + 16.98 whereas in Pb unexposed control group (n = 35 the range was 2.8 – 22.0 μg/dL (mean + SD, 12.52 + 4.08. The blood level (Pb-B and urinary lead level (Pb-U were significantly increased in BMW group as compared to unexposed control. Though activated d- aminolevulinic acid dehydratase (ALAD activities in BMW group did not show any significant change when compared to control group but activated / non activated erythrocyte – ALAD activities in BMW group showed a significant increase. Erythrocyte- zinc protoporphyrin (ZPP, urinary daminolevulinic acid (ALA-U and porphobilinogen (PBG-U of BMW groups elevated significantly as compared to control. A positive correlation (r = 0.66, p 1.0 were observed in control group. Hematological study revealed a significant decrease of hemoglobin concentration, packed cell volume (% and other blood indices and a significant increase of total leucocytes count in BMW group in comparison to control group. The serum MDA content was significantly increased (p< 0.001 and the activities of antioxidant enzymes such as erythrocyte- SOD (p< 0.001 and erythrocytecatalase (p< 0.001 were significantly reduced in BMW group as compared to control group. A positive correlation (r = 0.45, p<0.02 between Pb-B and serum MDA level was observed in BMW group (Pb-B range 25.8 – 78.0 μg / dL but such significant correlation did not notice in

Flux analysis of the Lactobacillus reuteri propanediol-utilization pathway for production of 3-hydroxypropionaldehyde, 3-hydroxypropionic acid and 1,3-propanediol from glycerol.

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Dishisha, Tarek; Pereyra, Luciana P; Pyo, Sang-Hyun; Britton, Robert A; Hatti-Kaul, Rajni

2014-05-27

Lactobacillus reuteri converts glycerol to 3-hydroxypropionic acid (3HP) and 1,3-propanediol (1,3PDO) via 3-hydroxypropionaldehyde (3HPA) as an intermediate using enzymes encoded in its propanediol-utilization (pdu) operon. Since 3HP, 1,3PDO and 3HPA are important building blocks for the bio-based chemical industry, L. reuteri can be an attractive candidate for their production. However, little is known about the kinetics of glycerol utilization in the Pdu pathway in L. reuteri. In this study, the metabolic fluxes through the Pdu pathway were determined as a first step towards optimizing the production of 3HPA, and co-production of 3HP and 1,3PDO from glycerol. Resting cells of wild-type (DSM 20016) and recombinant (RPRB3007, with overexpressed pdu operon) strains were used as biocatalysts. The conversion rate of glycerol to 3HPA by the resting cells of L. reuteri was evaluated by in situ complexation of the aldehyde with carbohydrazide to avoid the aldehyde-mediated inactivation of glycerol dehydratase. Under operational conditions, the specific 3HPA production rate of the RPRB3007 strain was 1.9 times higher than that of the wild-type strain (1718.2 versus 889.0 mg/gCDW.h, respectively). Flux analysis of glycerol conversion to 1,3PDO and 3HP in the cells using multi-step variable-volume fed-batch operation showed that the maximum specific production rates of 3HP and 1,3PDO were 110.8 and 93.7 mg/gCDW.h, respectively, for the wild-type strain, and 179.2 and 151.4 mg/gCDW.h, respectively, for the RPRB3007 strain. The cumulative molar yield of the two compounds was ~1 mol/mol glycerol and their molar ratio was ~1 mol3HP/mol1,3PDO. A balance of redox equivalents between the glycerol oxidative and reductive pathway branches led to equimolar amounts of the two products. Metabolic flux analysis was a useful approach for finding conditions for maximal conversion of glycerol to 3HPA, 3HP and 1,3PDO. Improved specific production rates were obtained with resting cells of

Metabolic transcription analysis of engineered Escherichia coli strains that overproduce L-phenylalanine

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Gosset Guillermo

2007-09-01

Full Text Available Abstract Background The rational design of L-phenylalanine (L-Phe overproducing microorganisms has been successfully achieved by combining different genetic strategies such as inactivation of the phosphoenolpyruvate: phosphotransferase transport system (PTS and overexpression of key genes (DAHP synthase, transketolase and chorismate mutase-prephenate dehydratase, reaching yields of 0.33 (g-Phe/g-Glc, which correspond to 60% of theoretical maximum. Although genetic modifications introduced into the cell for the generation of overproducing organisms are specifically targeted to a particular pathway, these can trigger unexpected transcriptional responses of several genes. In the current work, metabolic transcription analysis (MTA of both L-Phe overproducing and non-engineered strains using Real-Time PCR was performed, allowing the detection of transcriptional responses to PTS deletion and plasmid presence of genes related to central carbon metabolism. This MTA included 86 genes encoding enzymes of glycolysis, gluconeogenesis, pentoses phosphate, tricarboxylic acid cycle, fermentative and aromatic amino acid pathways. In addition, 30 genes encoding regulatory proteins and transporters for aromatic compounds and carbohydrates were also analyzed. Results MTA revealed that a set of genes encoding carbohydrate transporters (galP, mglB, gluconeogenic (ppsA, pckA and fermentative enzymes (ldhA were significantly induced, while some others were down-regulated such as ppc, pflB, pta and ackA, as a consequence of PTS inactivation. One of the most relevant findings was the coordinated up-regulation of several genes that are exclusively gluconeogenic (fbp, ppsA, pckA, maeB, sfcA, and glyoxylate shunt in the best PTS- L-Phe overproducing strain (PB12-ev2. Furthermore, it was noticeable that most of the TCA genes showed a strong up-regulation in the presence of multicopy plasmids by an unknown mechanism. A group of genes exhibited transcriptional responses to

Fucosylation Deficiency in Mice Leads to Colitis and Adenocarcinoma

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Wang, Yiwei; Huang, Dan; Chen, Kai-Yuan; Cui, Min; Wang, Weihuan; Huang, Xiaoran; Awadellah, Amad; Li, Qing; Friedman, Ann; Xin, William W.; Di Martino, Luca; Cominelli, Fabio; Miron, Alex; Chan, Ricky; Fox, James; Xu, Yan; Shen, Xiling; Kalady, Mathew F.; Markowitz, Sanford; Maillard, Ivan; Lowe, John B.; Xin, Wei; Zhou, Lan

2016-01-01

Background & Aims De novo synthesis of GDP-fucose, a substrate for fucosylglycans, requires sequential reactions mediated by GDP-mannose 4,6-dehydratase (GMDS) and GDP-4-keto-6-deoxymannose 3,5-epimerase-4-reductase (FX or TSTA3). GMDS deletions and mutations are found in 6%–13% of colorectal cancers; these mostly affect ascending and transverse colon. We investigated whether lack of fucosylation consequent to loss of GDP-fucose synthesis contributes to colon carcinogenesis. Methods FX deficiency and GMDS deletion produce the same biochemical phenotype of GDP-fucose deficiency. We studied a mouse model of fucosylation deficiency (Fx–/– mice) and mice with the full-length Fx gene (controls). Mice were placed on standard chow or fucose-containing diet (equivalent to a control fucosylglycan phenotype). Colon tissues were collected and analyzed histologically or by ELISAs to measure cytokine levels; T cells were also collected and analyzed. Fecal samples were analyzed by 16s rRNA sequencing. Mucosal barrier function was measured by uptake of fluorescent dextran. We transplanted bone marrow cells from Fx–/– or control mice (Ly5.2) into irradiated 8-week old Fx–/– or control mice (Ly5.1). We performed immunohistochemical analyses for expression of Notch and the hes family bHLH transcription factor (HES1) in colon tissues from mice and a panel of 60 human colorectal cancer specimens (27 left-sided, 33 right-sided). Results Fx–/– mice developed colitis and serrated-like lesions. The intestinal pathology of Fx–/– mice was reversed by addition of fucose to the diet, which restored fucosylation via a salvage pathway. In the absence of fucosylation, dysplasia appeared and progressed to adenocarcinoma in up to 40% of mice, affecting mainly the right colon and cecum. Notch was not activated in Fx–/– mice fed standard chow, leading to decreased expression of its target Hes1. Fucosylation deficiency altered the composition of the fecal microbiota, reduced

In Vivo-Selected Compensatory Mutations Restore the Fitness Cost of Mosaic penA Alleles That Confer Ceftriaxone Resistance in Neisseria gonorrhoeae.

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Vincent, Leah R; Kerr, Samuel R; Tan, Yang; Tomberg, Joshua; Raterman, Erica L; Dunning Hotopp, Julie C; Unemo, Magnus; Nicholas, Robert A; Jerse, Ann E

2018-04-03

Resistance to ceftriaxone in Neisseria gonorrhoeae is mainly conferred by mosaic penA alleles that encode penicillin-binding protein 2 (PBP2) variants with markedly lower rates of acylation by ceftriaxone. To assess the impact of these mosaic penA alleles on gonococcal fitness, we introduced the mosaic penA alleles from two ceftriaxone-resistant (Cro r ) clinical isolates (H041 and F89) into a Cro s strain (FA19) by allelic exchange and showed that the resultant Cro r mutants were significantly outcompeted by the Cro s parent strain in vitro and in a murine infection model. Four Cro r compensatory mutants of FA19 penA41 were isolated independently from mice that outcompeted the parent strain both in vitro and in vivo One of these compensatory mutants (LV41C) displayed a unique growth profile, with rapid log growth followed by a sharp plateau/gradual decline at stationary phase. Genome sequencing of LV41C revealed a mutation (G348D) in the acnB gene encoding the bifunctional aconitate hydratase 2/2 methylisocitrate dehydratase. Introduction of the acnB G348D allele into FA19 penA41 conferred both a growth profile that phenocopied that of LV41C and a fitness advantage, although not as strongly as that exhibited by the original compensatory mutant, suggesting the existence of additional compensatory mutations. The mutant aconitase appears to be a functional knockout with lower activity and expression than wild-type aconitase. Transcriptome sequencing (RNA-seq) analysis of FA19 penA41 acnB G348D revealed a large set of upregulated genes involved in carbon and energy metabolism. We conclude that compensatory mutations can be selected in Cro r gonococcal strains that increase metabolism to ameliorate their fitness deficit. IMPORTANCE The emergence of ceftriaxone-resistant (Cro r ) Neisseria gonorrhoeae has led to the looming threat of untreatable gonorrhea. Whether Cro resistance is likely to spread can be predicted from studies that compare the relative fitnesses of

Fucosylation Deficiency in Mice Leads to Colitis and Adenocarcinoma.

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Wang, Yiwei; Huang, Dan; Chen, Kai-Yuan; Cui, Min; Wang, Weihuan; Huang, Xiaoran; Awadellah, Amad; Li, Qing; Friedman, Ann; Xin, William W; Di Martino, Luca; Cominelli, Fabio; Miron, Alex; Chan, Ricky; Fox, James G; Xu, Yan; Shen, Xiling; Kalady, Mathew F; Markowitz, Sanford; Maillard, Ivan; Lowe, John B; Xin, Wei; Zhou, Lan

2017-01-01

De novo synthesis of guanosine diphosphate (GDP)-fucose, a substrate for fucosylglycans, requires sequential reactions mediated by GDP-mannose 4,6-dehydratase (GMDS) and GDP-4-keto-6-deoxymannose 3,5-epimerase-4-reductase (FX or tissue specific transplantation antigen P35B [TSTA3]). GMDS deletions and mutations are found in 6%-13% of colorectal cancers; these mostly affect the ascending and transverse colon. We investigated whether a lack of fucosylation consequent to loss of GDP-fucose synthesis contributes to colon carcinogenesis. FX deficiency and GMDS deletion produce the same biochemical phenotype of GDP-fucose deficiency. We studied a mouse model of fucosylation deficiency (Fx-/- mice) and mice with the full-length Fx gene (controls). Mice were placed on standard chow or fucose-containing diet (equivalent to a control fucosylglycan phenotype). Colon tissues were collected and analyzed histologically or by enzyme-linked immunosorbent assays to measure cytokine levels; T cells also were collected and analyzed. Fecal samples were analyzed by 16s ribosomal RNA sequencing. Mucosal barrier function was measured by uptake of fluorescent dextran. We transplanted bone marrow cells from Fx-/- or control mice (Ly5.2) into irradiated 8-week-old Fx-/- or control mice (Ly5.1). We performed immunohistochemical analyses for expression of Notch and the hes family bHLH transcription factor (HES1) in colon tissues from mice and a panel of 60 human colorectal cancer specimens (27 left-sided, 33 right-sided). Fx-/- mice developed colitis and serrated-like lesions. The intestinal pathology of Fx-/- mice was reversed by addition of fucose to the diet, which restored fucosylation via a salvage pathway. In the absence of fucosylation, dysplasia appeared and progressed to adenocarcinoma in up to 40% of mice, affecting mainly the right colon and cecum. Notch was not activated in Fx-/- mice fed standard chow, leading to decreased expression of its target Hes1. Fucosylation deficiency

Quantum mechanical approaches to in silico enzyme characterization and drug design

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Nilmeier, J P; Fattebert, J L; Jacobson, M P; Kalyanaraman, C

2012-01-17

substrate specificity. That is, we bring the power of quantum mechanics to bear on the problem of annotating enzyme function, which is a novel approach. Although it has been clear to us at the Jacobson group for some time that enzyme specificity may be encoded in transition states, rather than simply substrate recognition, the main limitation has always been computational expense. Using a hierarchy of different methods, they can reduce the list of plausible substrates of an enzyme to a small number in most cases, but even identifying the transition states for a dozen plausible substrates requires significant computational effort, beyond what is practical using standard QM/MM methods. For this project, they have chosen two enzyme superfamilies which they have used as 'model systems' for functional assignment. The enolase superfamily is a large group of {alpha}-{beta} barrel enzymes with highly diverse substrates and chemical transformations. Despite decades of work, over a third of the superfamily remains unassigned, which means that the remaining cases are by definition difficult to assign. They have focused on acid sugar dehydratases, and have considerable expertise on the matter. They are also interested in the isoprenoid synthase superfamily, which is of central interest to the synthetic biology community, because these enzymes are used by nature to create complex rare natural products of medicinal value. the most notable example of this is the artemisinin, an antimalarial compound that is found in trace amounts in the wormwod root. From the standpoint of enzyme function assignment, these enzymes are intriguing because they use a small number of chemically simple substrates to generate, potentially, tens of thousands of different products. Hence, substrate binding specificity is only a small part of the challenge; the key is determining how the enzyme directs the carbocation chemistry to specific products. These more complex modeling approaches clearly require

Catabolism of biomass-derived sugars in fungi and metabolic engineering as a tool for organic acid production

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Koivistoinen, O.

2013-11-01

The use of metabolic engineering as a tool for production of biochemicals and biofuels requires profound understanding of cell metabolism. The pathways for the most abundant and most important hexoses have already been studied quite extensively but it is also important to get a more complete picture of sugar catabolism. In this thesis, catabolic pathways of L-rhamnose and D-galactose were studied in fungi. Both of these hexoses are present in plant biomass, such as in hemicellulose and pectin. Galactoglucomannan, a type of hemicellulose that is especially rich in softwood, is an abundant source of D-galactose. As biotechnology is moving from the usage of edible and easily metabolisable carbon sources towards the increased use of lignocellulosic biomass, it is important to understand how the different sugars can be efficiently turned into valuable biobased products. Identification of the first fungal L-rhamnose 1-dehydrogenase gene, which codes for the first enzyme of the fungal catabolic L-rhamnose pathway, showed that the protein belongs to a protein family of short-chain alcohol dehydrogenases. Sugar dehydrogenases oxidising a sugar to a sugar acid are not very common in fungi and thus the identification of the L-rhamnose dehydrogenase gene provides more understanding of oxidative sugar catabolism in eukaryotic microbes. Further studies characterising the L-rhamnose cluster in the yeast Scheffersomyces stipitis including the expression of the L-rhamnonate dehydratase in Saccharomyces cerevisiae finalised the biochemical characterisation of the enzymes acting on the pathway. In addition, more understanding of the regulation and evolution of the pathway was gained. D-Galactose catabolism was studied in the filamentous fungus Aspergillus niger. Two genes coding for the enzymes of the oxido-reductive pathway were identified. Galactitol dehydrogenase is the second enzyme of the pathway converting galactitol to L-xylo-3-hexulose. The galactitol dehydrogenase encoding

In silico Design of "Un-Natural" Natural Products

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Zucko; J. ...(et al.

2008-05-01

Full Text Available Polyketides and non-ribosomal peptides represent a large class of structurally diverse natural products much studied over recent years because the enzymes that synthesise them, the modular polyketide synthases (PKSs and the non-ribosomal peptide synthetases (NRPSs, share striking architectural similarities that can be exploited to generate "un-natural" natural products. PKS and NRPS proteins are multifunctional, composed of a co-linear arrangement of discrete protein domains representing each enzymic activity needed for chain elongation using either carboxylic acid or amino acid building blocks. Each domain is housed within larger modules which form the complex. Polyketide and peptide antibiotics, antifungals, antivirals, cytostatics, immunosuppressants, antihypertensives, antidiabetics, antimalarials and anticholesterolemics are in clinical use. Of commercial importance are also polyketide and peptide antiparasitics, coccidiostatics,animal growth promoters and natural insecticides.Polyketides are assembled through serial condensations of activated coenzyme-A thioester monomers derived from simple organic acids such as acetate, propionate and butyrate. The choice of organic acid allows the introduction of different chiral centres into the polyketide backbone. The active sites required for condensation include an acyltransferase (AT, an acyl carrier protein (ACP and a ß-ketoacylsynthase (KS. Each condensation results in a ß-keto group that undergoes all, some or none of a series of processing steps. Active sites that perform these reactions are contained within the following domains; ketoreductase (KR, dehydratase (DH and an enoylreductase (ER. The absence of any ß-keto processing results in the incorporation of a ketone group into the growing polyketide chain, a KR alone gives rise to a hydroxyl moiety, a KR and DH produce an alkene, while the combination of KR, DH and ER domains lead to complete reduction to an alkane. Most often, the last