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Sample records for peroxidase enhances tolerance

  1. A Novel Thylakoid Ascorbate Peroxidase from Jatrophacurcas Enhances Salt Tolerance in Transgenic Tobacco

    PubMed Central

    Liu, Zhibin; Bao, Han; Cai, Jin; Han, Jun; Zhou, Lirong

    2014-01-01

    Ascorbate peroxidase (APX) plays an important role in the metabolism of hydrogen peroxide in higher plants. In the present study, a novel APX gene (JctAPX) was cloned from Jatropha curcas L. The deduced amino acid sequence was similar to that of APX of some other plant species. JctAPX has a chloroplast transit peptide and was localized to the chloroplasts by analysis with a JctAPX-green fluorescent protein (GFP) fusion protein. Quantitative polymerase chain reaction (qPCR) analysis showed that JctAPX was constitutively expressed in different tissues from J. curcas and was upregulated by NaCl stress. To characterize its function in salt tolerance, the construct p35S: JctAPX was created and successfully introduced into tobacco by Agrobacterium-mediated transformation. Compared with wild type (WT), the transgenic plants exhibited no morphological abnormalities in the no-stress condition. However, under 200 mM NaCl treatment, JctAPX over-expressing plants showed increased tolerance to salt during seedling establishment and growth. In addition, the transgenic lines showed higher chlorophyll content and APX activity, which resulted in lower H2O2 content than WT when subjected to 400 mM NaCl stress. These results suggest that the increased APX activity in the chloroplasts from transformed plants increased salt tolerance by enhancing reactive oxygen species (ROS)-scavenging capacity under short-term NaCl stress conditions. PMID:24368517

  2. Ascorbate peroxidase from Jatropha curcas enhances salt tolerance in transgenic Arabidopsis.

    PubMed

    Chen, Y; Cai, J; Yang, F X; Zhou, B; Zhou, L R

    2015-01-01

    Ascorbate peroxidase (APX) plays a central role in the ascorbate-glutathione cycle and is a key enzyme in cellular H2O2 me-tabolism. It includes a family of isoenzymes with different character-istics, which are identified in many higher plants. In the present study, we isolated the APX gene from Jatropha curcas L, which is similar with other previously characterized APXs as revealed by alignment and phylogenetic analysis of its deduced amino acid sequence. Real-time qPCR analysis showed that the expression level of JcAPX transcript significantly increased under NaCl stress. Subsequently, to elucidate the contribution of JcAPX to the protection against salt-induced oxi-dative stress, the expression construct p35S: JcAPX was created and transformed into Arabidopsis and transcribed. Under 150-mM NaCl stress, compared with wild type (WT), the overexpression of JcAPX in Arabidopsis increased the germination rate, the number of leaves, and the rosette area. In addition, the transgenic plants had longer roots, higher total chlorophyll content, higher total APX activity, and lower H2O2 content than the WT under NaCl stress conditions. These results suggested that higher APX activity in transgenic lines increases the salt tolerance by enhancing scavenging capacity for reactive oxygen spe-cies under NaCl stress conditions. PMID:25966262

  3. Cloning a glutathione peroxidase gene from Nelumbo nucifera and enhanced salt tolerance by overexpressing in rice.

    PubMed

    Diao, Ying; Xu, Huaxue; Li, Guolin; Yu, Aiqing; Yu, Xia; Hu, Wanling; Zheng, Xingfei; Li, Shaoqing; Wang, Youwei; Hu, Zhongli

    2014-08-01

    A full-length cDNA clone encoding an 866 bp-length glutathione peroxidase protein (NnGPX) was isolated from lotus (Nelumbo nucifera L.). The deduced amino acid sequence of the NnGPX gene had significant homology with ATGPX6. A 3D structural model of the NnGPX was constructed by homology modeling. The cloned NnGPX gene was expressed in Escherichia coli, and a fusion protein of about 40 kDa was detected after isopropyl thiogalactoside induction. Under different concentrations of Na2SeO3 treatments, NnGPX was found to be an enzyme that does not contain selenium. Real-time PCR analysis showed that the NnGPX gene was expressed in all organs of lotus, and its high expression mainly occurred in organs with active metabolisms. NnGPX transcript increased remarkably in response to cold, heat, mechanical damage, and salt treatment. Subsequently, the NnGPX gene was introduced in Oryza sativa cv. Yuetai B. PCR results verified the integration of this gene into the genome of rice and reverse transcription-PCR verified that this gene had been expressed in transgenic rice. The transgenic plants were significantly more tolerant to salt stress compared with the wild-type. PMID:24715609

  4. Over-expression of ascorbate peroxidase in tobacco chloroplasts enhances the tolerance to salt stress and water deficit.

    PubMed

    Badawi, Ghazi Hamid; Kawano, Naoyoshi; Yamauchi, Yasuo; Shimada, Emi; Sasaki, Ryozo; Kubo, Akihiro; Tanaka, Kiyoshi

    2004-06-01

    The role of APX (ascorbate peroxidase) in protection against oxidative stress was examined using transgenic tobacco plants. The full length cDNA, coding Arabidopsis thaliana L. APX fused downstream to the chloroplast transit sequence from A. thaliana glutathione reductase, was cloned into appropriate binary vector and mobilized into Agrobacterium tumefaciens C58C2. Leaf discs were infected with the Agrobacterium and cultured on medium supplied with kanamycin. The incorporation of the gene in tobacco genome was confirmed by Southern dot blot hybridization. Transgenic lines were generated, and the line Chl-APX5 shown to have 3.8-fold the level of APX activity in the wild-type plants. The isolated chloroplasts from this line showed higher APX activity. During early investigation, this line showed enhanced tolerance to the active oxygen-generating paraquat and sodium sulphite. The first generation of this line, also, showed enhanced tolerance to salt, PEG and water stresses, as determined by net photosynthesis. The present data indicate that overproducing the cytosolic APX in tobacco chloroplasts reduces the toxicity of H(2)O(2). PMID:15153190

  5. Creation of a Thermally Tolerant Peroxidase.

    PubMed

    Watanabe, Y; Nakajima, H

    2016-01-01

    An artificial peroxidase with thermal tolerance and high catalytic activity has been successfully prepared by mutagenesis of an electron transfer protein, cytochrome c552 from Thermus thermophilus. The mutant enzymes were rationally designed based on the general peroxidase mechanism and spectroscopic analyses of an active intermediate formed in the catalytic reaction. Stopped flow UV-vis spectroscopy and EPR spectroscopy with a rapid freezing sample technique revealed that the initial double mutant, V49D/M69A, which was designed to reproduce the peroxidase mechanism, formed an active oxo-ferryl heme intermediate with a protein radical predominantly localized on Tyr45 during the catalytic reaction. The magnetic power saturation measurement obtained from EPR studies showed little interaction between the oxo-ferryl heme and the tyrosyl radical. Kinetics studies indicated that the isolated oxo-ferryl heme component in the active intermediate was a possible cause of heme degradation during the reaction with H2O2. Strong interaction between the oxo-ferryl heme and the radical was achieved by replacing Tyr45 with tryptophan (resulting in the Y45W/V49D/M69A mutant), which was similar to a tryptophanyl radical found in active intermediates of some catalase-peroxidases. Compared to the protein radical intermediates of V49D/M69A mutant, those of the Y45W/V49D/M69A mutant showed higher reactivity to an organic substrate than to H2O2. The Y45W/V49D/M69A mutant exhibited improved peroxidase activity and thermal tolerance. PMID:27586345

  6. Glutathione Peroxidase of Pennisetum glaucum (PgGPx) Is a Functional Cd2+ Dependent Peroxiredoxin that Enhances Tolerance against Salinity and Drought Stress

    PubMed Central

    Islam, Tahmina; Manna, Mrinalini; Reddy, Malireddy K.

    2015-01-01

    Reactive oxygen species (ROS) arise in the plant system due to inevitable influence of various environmental stimuli. Glutathione peroxidases are one of the important ROS scavengers inside the cell. A glutathione peroxidase (PgGPx) gene was previously found from Pennisetum glauccum abiotic stressed cDNA library. Enzyme kinetics data revealed that PgGPx possessed preference towards thioredoxin rather than glutathione as electron donor and thus belongs to the functional peroxiredoxin group. Moreover, its activity was found to be dependent on divalent cations, especially Cd2+ and homology model showed the presence of Cd2+ binding site in the protein. Site directed mutagenesis study of PgGPx protein revealed the vital role of two conserved Cysteine residues for its enzymatic activity and structural folding. Expression analysis suggested that PgGPx transcript is highly up-regulated in response to salinity and drought stresses. When expressed ectopically, PgGPx showed enhanced tolerance against multiple abiotic stresses in prokaryotic E. coli and model plant, rice. Transgenic rice plants showed lesser accumulation of MDA and H2O2; and higher accumulation of proline as compared to wild type (WT) plants in response to both salinity and drought stresses that clearly indicates suppression of lipid peroxidation and ROS generation in transgenic lines. Moreover, transgenic plants maintained better photosynthesis efficiency and higher level of antioxidant enzyme activity as compared to WT plants under stress conditions. These results clearly indicate the imperative role of PgGPx in cellular redox homeostasis under stress conditions, leading to the maintenance of membrane integrity and increased tolerance towards oxidative stress. PMID:26600014

  7. ATP-enhanced peroxidase-like activity of gold nanoparticles.

    PubMed

    Shah, Juhi; Purohit, Rahul; Singh, Ragini; Karakoti, Ajay Singh; Singh, Sanjay

    2015-10-15

    Gold nanoparticles (AuNPs) are known to possess intrinsic biological peroxidase-like activity that has applications in development of numerous biosensors. The reactivity of the Au atoms at the surface of AuNPs is critical to the performance of such biosensors, yet little is known about the effect of biomolecules and ions on the peroxidase-like activity. In this work, the effect of ATP and other biologically relevant molecules and ions over peroxidase-like activity of AuNPs are described. Contrary to the expectation that nanoparticles exposed to biomolecules may lose the catalytic property, ATP and ADP addition enhanced the peroxidase-like activity of AuNPs. The catalytic activity was unaltered by the addition of free phosphate, sulphate and carbonate anions however, addition of ascorbic acid to the reaction mixture diminished the intrinsic peroxidase-like activity of AuNPs, even in the presence of ATP and ADP. In contrast to AuNPs, ATP did not synergize and improve the peroxidase activity of the natural peroxidase enzyme, horseradish peroxidase. PMID:26111515

  8. The role of hydrogen peroxide-producing and hydrogen peroxide-consuming peroxidases in the leaf apoplast of cowpea in manganese tolerance.

    PubMed

    Fecht-Christoffers, Marion Maria; Führs, Hendrik; Braun, Hans-Peter; Horst, Walter Johannes

    2006-04-01

    The apoplast is considered the leaf compartment decisive for manganese (Mn) toxicity and tolerance in cowpea (Vigna unguiculata). Particularly apoplastic peroxidases (PODs) were proposed to be key enzymes in Mn toxicity-induced processes. The presented work focuses on the characterization of the role of hydrogen peroxide (H2O2)-producing (NADH peroxidase) and H2O2-consuming peroxidase (guaiacol POD) in the apoplastic washing fluid (AWF) of leaves for early stages of Mn toxicity and genotypic differences in Mn tolerance of cowpea. Leaf AWF of the Mn-sensitive cultivar (cv) TVu 91 but not of the Mn-tolerant cv 1987 showed an increase of guaiacol-POD and NADH-peroxidase activities at elevated AWF Mn concentrations. two-dimensional resolutions of AWF proteins revealed that cv TVu 91 expressed more and additional proteins at high Mn treatment, whereas Mn-tolerant cv TVu 1987 remained nearly unaffected. In both cultivars, NADH-peroxidase activity and accompanied H2O2 formation rate in vitro were significantly affected by Mn2+, p-coumaric acid, and metabolites occurring in the AWF. The total phenol concentration in the AWF was indicative of advanced stages of Mn toxicity but was rather unrelated to early stages of Mn toxicity and genotypic differences in Mn tolerance. The NADH oxidation by AWF PODs was significantly delayed or enhanced in the presence of the protein-free AWF from cv TVu 1987 or cv TVu 91, respectively. High-performance liquid chromatography analysis of AWF indicates the presence of phenols in cv TVu 1987 not observed in cv TVu 91. We conclude from our studies that the H2O2-producing NADH peroxidase and its modulation by stimulating or inhibiting phenolic compounds in the leaf apoplast play a major role for Mn toxicity and Mn tolerance in cowpea. PMID:16489137

  9. Different peroxidase activities and expression of abiotic stress-related peroxidases in apical root segments of wheat genotypes with different drought stress tolerance under osmotic stress.

    PubMed

    Csiszár, Jolán; Gallé, Agnes; Horváth, Edit; Dancsó, Piroska; Gombos, Magdolna; Váry, Zsolt; Erdei, László; Györgyey, János; Tari, Irma

    2012-03-01

    One-week-old seedlings of Triticum aestivum L. cv. Plainsman V, a drought tolerant; and Cappelle Desprez, a drought sensitive wheat cultivar were subjected gradually to osmotic stress using polyethylene glycol (PEG 6000) reaching 400 mOsm on the 11th day. Compared to controls cv. Plainsman V maintained the root growth and relative water content of root tissues, while these parameters were decreased in the drought sensitive cv. Cappelle Desprez under PEG-mediated osmotic stress. Simultaneously, H(2)O(2) content in 1-cm-long apical segment of roots comprising the proliferation and elongation zone, showed a transient increase in cv. Plainsman V and a permanent raise in cv. Cappelle Desprez. Measurements of the transcript levels of selected class III peroxidase (TaPrx) coding sequences revealed significant differences between the two cultivars on the 9th day, two days after applying 100 mOsm PEG. The abundance of TaPrx04 transcript was enhanced transitionally in the root apex of cv. Plainsman V but decreased in cv. Cappelle Desprez under osmotic stress while the expression of TaPrx01, TaPrx03, TaPrx19, TaPrx68, TaPrx107 and TaPrx109-C decreased to different extents in both cultivars. After a transient decrease, activities of soluble peroxidase fractions of crude protein extracts rose in both cultivars on day 11, but the activities of cell wall-bound fractions increased only in cv. Cappelle Desprez under osmotic stress. Parallel with high H(2)O(2) content of the tissues, certain isoenzymes of covalently bound fraction in cv. Cappelle Desprez showed increased activity suggesting that they may limit the extension of root cell walls in this cultivar. PMID:22305075

  10. Biotechnological advances towards an enhanced peroxidase production in Pichia pastoris.

    PubMed

    Krainer, Florian W; Gerstmann, Michaela A; Darnhofer, Barbara; Birner-Gruenberger, Ruth; Glieder, Anton

    2016-09-10

    Horseradish peroxidase (HRP) is a high-demand enzyme for applications in diagnostics, bioremediation, biocatalysis and medicine. Current HRP preparations are isolated from horseradish roots as mixtures of biochemically diverse isoenzymes. Thus, there is a strong need for a recombinant production process enabling a steady supply with enzyme preparations of consistent high quality. However, most current recombinant production systems are limited at titers in the low mg/L range. In this study, we used the well-known yeast Pichia pastoris as host for recombinant HRP production. To enhance recombinant enzyme titers we systematically evaluated engineering approaches on the secretion process, coproduction of helper proteins, and compared expression from the strong methanol-inducible PAOX1 promoter, the strong constitutive PGAP promoter, and a novel bidirectional promoter PHTX1. Ultimately, coproduction of HRP and active Hac1 under PHTX1 control yielded a recombinant HRP titer of 132mg/L after 56h of cultivation in a methanol-independent and easy-to-do bioreactor cultivation process. With regard to the many versatile applications for HRP, the establishment of a microbial host system suitable for efficient recombinant HRP production was highly overdue. The novel HRP production platform in P. pastoris presented in this study sets a new benchmark for this medically relevant enzyme. PMID:27432633

  11. Over-expression of the peroxisomal ascorbate peroxidase (SbpAPX) gene cloned from halophyte Salicornia brachiata confers salt and drought stress tolerance in transgenic tobacco.

    PubMed

    Singh, Natwar; Mishra, Avinash; Jha, Bhavanath

    2014-06-01

    Salicornia brachiata Roxb., an extreme halophyte, is a naturally adapted higher plant model for additional gene resources to engineer salt tolerance in plants. Ascorbate peroxidase (APX) plays a key role in protecting plants against oxidative stress and thus confers abiotic stress tolerance. A full-length SbpAPX cDNA, encoding peroxisomal ascorbate peroxidase, was cloned from S. brachiata. The open reading frame encodes for a polypeptide of 287 amino acid residues (31.3-kDa protein). The deduced amino acid sequence of the SbpAPX gene showed characteristic peroxisomal targeting sequences (RKRAI) and a C-terminal hydrophobic region of 39 amino acid residues containing a transmembrane domain (TMD) of 23 amino acid residues. Northern blot analysis showed elevated SbpAPX transcript in response to salt, cold, abscisic acid and salicylic acid stress treatments. The SbpAPX gene was transformed to tobacco for their functional validation under stresses. Transgenic plants over-expressing SbpAPX gene showed enhanced salt and drought stress tolerance compared to wild-type plants. Transgenic plants showed enhanced vegetative growth and germination rate both under normal and stressed conditions. Present study revealed that the SbpAPX gene is a potential candidate, which not only confers abiotic stress tolerance to plants but also seems to be involved in plant growth. PMID:24197564

  12. Phenolic mediators enhance the manganese peroxidase catalyzed oxidation of recalcitrant lignin model compounds and synthetic lignin.

    PubMed

    Nousiainen, Paula; Kontro, Jussi; Manner, Helmiina; Hatakka, Annele; Sipilä, Jussi

    2014-11-01

    Fungal oxidative enzymes, such as peroxidases and laccases, are the key catalysts in lignin biodegradation in vivo, and consequently provide an important source for industrial ligninolytic biocatalysts. Recently, it has been shown that some syringyl-type phenolics have potential as industrial co-oxidants or mediators, in laccase-catalyzed modification of lignocellulosic material. We have now studied the effect of such mediators with ligninolytic peroxidases on oxidation of the most recalcitrant lignin model compounds. We found that they are able to enhance the manganese peroxidase (MnP) catalyzed oxidation reactions of small non-phenolic compounds, veratryl alcohol and veratrylglycerol β-guaiacyl ether (adlerol), which are not usually oxidized by manganese peroxidases alone. In these experiments we compared two peroxidases from white-rot fungi, MnP from Phlebia sp. Nf b19 and versatile peroxidase (VP) from Bjerkandera adusta under two oxidation conditions: (i) the Mn(III) initiated mediated oxidation by syringyl compounds and (ii) the system involving MnP-dependent lipid peroxidation, both with production of (hydrogen) peroxides in situ to maintain the peroxidase catalytic cycle. It was found that both peroxidases produced α-carbonyl oxidation product of veratryl alcohol in clearly higher yields in reactions mediated by phenoxy radicals than in lipid-peroxyl radical system. The oxidation of adlerol, on the other hand, was more efficient in lipid-peroxidation-system. VP was more efficient than MnP in the oxidation of veratryl alcohol and showed its lignin peroxidase type activity in the reaction conditions indicated by some cleavage of Cα-Cβ-bond of adlerol. Finally, the mediator assisted oxidation conditions were applied in the oxidation of synthetic lignin (DHP) and the structural analysis of the oxidized polymers showed clear modifications in the polymer outcome, e.g. the oxidation resulted in reduced amount of aliphatic hydroxyls indicated by (31)P NMR. PMID

  13. IMPROVED TOLERANCE TO ENVIRONMENTALLY INDUCED OXIDATIVE STRESSES IN TRANSGENIC TOMATO OVEREXPRESSING ASCORBATE PEROXIDASE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We studied the effect on oxidative stress resistance of overexpressing, in transgenic tomato (Lycopersicon esculentum) plants, a cytosolic ascorbate peroxidase (APX) gene derived from pea (Pisum sativum). Transformants were selected using Kanamycin resistance and confirmed by PCR, Southern and Nort...

  14. Chemical enhancement of footwear impressions in blood on fabric - part 2: peroxidase reagents.

    PubMed

    Farrugia, Kevin J; Savage, Kathleen A; Bandey, Helen; Ciuksza, Tomasz; Nic Daéid, Niamh

    2011-09-01

    This study investigates the optimisation of peroxidase based enhancement techniques for footwear impressions made in blood on various fabric surfaces. Four different haem reagents: leuco crystal violet (LCV), leuco malachite green (LMG), fluorescein and luminol were used to enhance the blood contaminated impressions. The enhancement techniques in this study were used successfully to enhance the impressions in blood on light coloured surfaces, however, only fluorescent and/or chemiluminescent techniques allowed visualisation on dark coloured fabrics, denim and leather. Luminol was the only technique to enhance footwear impressions made in blood on all the fabrics investigated in this study. PMID:21889107

  15. Cationic Peptide Conjugation Enhances the Activity of Peroxidase-Mimicking DNAzymes.

    PubMed

    Xiao, Lu; Zhou, Zhaojuan; Feng, Mengli; Tong, Aijun; Xiang, Yu

    2016-03-16

    Peroxidase-mimicking DNAzymes containing G-quadruplex structures are widely applied in chemistry as catalysts and signal amplification for biosensing. Enhancing the catalytic activity of these DNAzymes can therefore improve the performance of many catalysts and biosensors using them. In this work, we synthesized cationic peptide conjugates of peroxidase-mimicking DNAzymes, which were found to exhibit both enhanced peroxidase and oxidase activities up to 4-fold and 3-fold compared with the original DNAzymes, respectively. Further investigation suggested that the enhanced activity was ascribed to the stabilization of parallel DNA G-quadruplex structures and hemin binding by the cationic peptide covalently attached to the DNAzyme. Such a mechanism of activity enhancement was successfully utilized for biosensing applications with improved sensitivity and broadened target range. Hydrogen peroxide (H2O2) detection in K(+)-free solutions by the DNAzyme-peptide conjugate showed 2-fold sensitivity enhancement over the unmodified DNAzyme under the same condition, and the activity switch by target-induced cleavage of the DNAzyme-peptide conjugate was also used for the detection of caspase 3 protease with enzymatic amplification in homogeneous solutions. PMID:26751843

  16. Biocatalysts with enhanced inhibitor tolerance

    DOEpatents

    Yang, Shihui; Linger, Jeffrey; Franden, Mary Ann; Pienkos, Philip T.; Zhang, Min

    2015-12-08

    Disclosed herein are biocatalysts for the production of biofuels, including microorganisms that contain genetic modifications conferring tolerance to growth and fermentation inhibitors found in many cellulosic feedstocks. Methods of converting cellulose-containing materials to fuels and chemicals, as well as methods of fermenting sugars to fuels and chemicals, using these biocatalysts are also disclosed.

  17. The rice thylakoid membrane-bound ascorbate peroxidase OsAPX8 functions in tolerance to bacterial blight

    PubMed Central

    Jiang, Guanghuai; Yin, Dedong; Zhao, Jiying; Chen, Honglin; Guo, Lequn; Zhu, Lihuang; Zhai, Wenxue

    2016-01-01

    Thylakoid membrane-bound ascorbate peroxidase (tAPX) is a major H2O2-scavenging enzyme. To clarify its functions in tolerance to rice bacterial blight, we produced rice lines overexpressing and suppressing tAPX (OsAPX8). The overexpressing lines exhibited increased tolerance to bacterial pathogen. The RNA interference (RNAi) lines were considerably more sensitive than the control plant. Further analysis of the H2O2 content in these transgenic plants indicated that the H2O2 accumulation of OsAPX8-overexpressing plants was considerably less than that of wild-type and RNAi plants upon challenge with bacterial pathogen. Interestingly, H2O2 was the most important factor for the serious leaf dehydration and withering of rice without major resistance genes and was not the cause of hypersensitivity. It addition, wall tightening or loosening can occur according to the level of H2O2. In addition, OsAPX8 interacted with the susceptibility protein Os8N3/Xa13, and their binding repressed the reaction of OsAPX8 in tolerance to bacterial blight. PMID:27185545

  18. Enhancement of reproductive heat tolerance in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The current study investigated the enhancement of plant reproductive heat tolerance through the use of a gene encoding the Arabidopsis thaliana heat shock protein 101 (AtHSP101) not normally expressed in pollen but reported to play a crucial role in vegetative thermotolerance. The Arabidopsis thali...

  19. Nucleic acid molecules conferring enhanced ethanol tolerance and microorganisms having enhanced tolerance to ethanol

    DOEpatents

    Brown, Steven; Guss, Adam; Yang, Shihui; Karpinets, Tatiana; Lynd, Lee; Shao, Xiongjun

    2014-01-14

    The present invention provides isolated nucleic acid molecules which encode a mutant acetaldehyde-CoA/alcohol dehydrogenase or mutant alcohol dehydrogenase and confer enhanced tolerance to ethanol. The invention also provides related expression vectors, genetically engineered microorganisms having enhanced tolerance to ethanol, as well as methods of making and using such genetically modified microorganisms for production of biofuels based on fermentation of biomass materials.

  20. Transcriptional regulation of heat shock proteins and ascorbate peroxidase by CtHsfA2b from African bermudagrass conferring heat tolerance in Arabidopsis

    PubMed Central

    Wang, Xiuyun; Huang, Wanlu; Yang, Zhimin; Liu, Jun; Huang, Bingru

    2016-01-01

    Heat stress transcription factor A2s (HsfA2s) are key regulators in plant response to high temperature. Our objectives were to isolate an HsfA2 gene (CtHsfA2b) from a warm-season grass species, African bermudagrass (Cynodon transvaalensis Burtt-Davy), and to determine the physiological functions and transcriptional regulation of HsfA2 for improving heat tolerance. Gene expression analysis revealed that CtHsfA2b was heat-inducible and exhibited rapid response to increasing temperature. Ectopic expression of CtHsfA2b improved heat tolerance in Arabidopsis and restored heat-sensitive defects of Arabidopsis hsfa2 mutant, which was demonstrated by higher survival rate and photosynthetic parameters, and lower electrolyte leakage in transgenic plants compared to the WT or hsfa2 mutant. CtHsfA2b transgenic plants showed elevated transcriptional regulation of several downstream genes, including those encoding ascorbate peroxidase (AtApx2) and heat shock proteins [AtHsp18.1-CI, AtHsp22.0-ER, AtHsp25.3-P and AtHsp26.5-P(r), AtHsp70b and AtHsp101-3]. CtHsfA2b was found to bind to the heat shock element (HSE) on the promoter of AtApx2 and enhanced transcriptional activity of AtApx2. These results suggested that CtHsfA2b could play positive roles in heat protection by up-regulating antioxidant defense and chaperoning mechanisms. CtHsfA2b has the potential to be used as a candidate gene to genetically modify cool-season species for improving heat tolerance. PMID:27320381

  1. Transcriptional regulation of heat shock proteins and ascorbate peroxidase by CtHsfA2b from African bermudagrass conferring heat tolerance in Arabidopsis.

    PubMed

    Wang, Xiuyun; Huang, Wanlu; Yang, Zhimin; Liu, Jun; Huang, Bingru

    2016-01-01

    Heat stress transcription factor A2s (HsfA2s) are key regulators in plant response to high temperature. Our objectives were to isolate an HsfA2 gene (CtHsfA2b) from a warm-season grass species, African bermudagrass (Cynodon transvaalensis Burtt-Davy), and to determine the physiological functions and transcriptional regulation of HsfA2 for improving heat tolerance. Gene expression analysis revealed that CtHsfA2b was heat-inducible and exhibited rapid response to increasing temperature. Ectopic expression of CtHsfA2b improved heat tolerance in Arabidopsis and restored heat-sensitive defects of Arabidopsis hsfa2 mutant, which was demonstrated by higher survival rate and photosynthetic parameters, and lower electrolyte leakage in transgenic plants compared to the WT or hsfa2 mutant. CtHsfA2b transgenic plants showed elevated transcriptional regulation of several downstream genes, including those encoding ascorbate peroxidase (AtApx2) and heat shock proteins [AtHsp18.1-CI, AtHsp22.0-ER, AtHsp25.3-P and AtHsp26.5-P(r), AtHsp70b and AtHsp101-3]. CtHsfA2b was found to bind to the heat shock element (HSE) on the promoter of AtApx2 and enhanced transcriptional activity of AtApx2. These results suggested that CtHsfA2b could play positive roles in heat protection by up-regulating antioxidant defense and chaperoning mechanisms. CtHsfA2b has the potential to be used as a candidate gene to genetically modify cool-season species for improving heat tolerance. PMID:27320381

  2. Enhanced chemiluminescence of the luminol-hydrogen peroxide system by colloidal cupric oxide nanoparticles as peroxidase mimic.

    PubMed

    Chen, Wei; Hong, Lei; Liu, Ai-Lin; Liu, Jian-Qing; Lin, Xin-Hua; Xia, Xing-Hua

    2012-09-15

    As a peroxidase mimic, cupric oxide nanoparticles were found to enhance the chemiluminescence (CL) of luminol-H(2)O(2) system up to 400 folds. The CL spectra and radical scavengers were conducted to investigate the possible CL enhancement mechanism. It was suggested that the enhanced CL could be attributed to the peroxidase-like activity of CuO nanoparticles, which effectively catalyzed the decomposition of hydrogen peroxide into hydroxyl radicals. The effects of the reactant concentrations and some organic compounds were also investigated. The proposed method could be used as a sensitive detection tool for hydrogen peroxide and glucose. PMID:22967606

  3. Enhanced Accident Tolerant LWR Fuels: Metrics Development

    SciTech Connect

    Shannon Bragg-Sitton; Lori Braase; Rose Montgomery; Chris Stanek; Robert Montgomery; Lance Snead; Larry Ott; Mike Billone

    2013-09-01

    The Department of Energy (DOE) Fuel Cycle Research and Development (FCRD) Advanced Fuels Campaign (AFC) is conducting research and development on enhanced Accident Tolerant Fuels (ATF) for light water reactors (LWRs). This mission emphasizes the development of novel fuel and cladding concepts to replace the current zirconium alloy-uranium dioxide (UO2) fuel system. The overall mission of the ATF research is to develop advanced fuels/cladding with improved performance, reliability and safety characteristics during normal operations and accident conditions, while minimizing waste generation. The initial effort will focus on implementation in operating reactors or reactors with design certifications. To initiate the development of quantitative metrics for ATR, a LWR Enhanced Accident Tolerant Fuels Metrics Development Workshop was held in October 2012 in Germantown, MD. This paper summarizes the outcome of that workshop and the current status of metrics development for LWR ATF.

  4. Ferromagnetic nanoparticles with peroxidase-like activity enhance the cleavage of biological macromolecules for biofilm elimination

    NASA Astrophysics Data System (ADS)

    GaoCurrent Address: University Of Pennsylvania, School Of Dental Medicine, Philadelphia, Pa 19104, Usa. E.-Mail: Gaoliz@Dental. Upenn. Edu, Lizeng; Giglio, Krista M.; Nelson, Jacquelyn L.; Sondermann, Holger; Travis, Alexander J.

    2014-02-01

    Hydrogen peroxide (H2O2) is a ``green chemical'' that has various cleaning and disinfectant uses, including as an anti-bacterial agent for hygienic and medical treatments. However, its efficacy is limited against biofilm-producing bacteria, because of poor penetration into the protective, organic matrix. Here we show new applications for ferromagnetic nanoparticles (Fe3O4, MNPs) with peroxidase-like activity in potentiating the efficacy of H2O2 in biofilm degradation and prevention. Our data show that MNPs enhanced oxidative cleavage of biofilm components (model nucleic acids, proteins, and oligosaccharides) in the presence of H2O2. When challenged with live, biofilm-producing bacteria, the MNP-H2O2 system efficiently broke down the existing biofilm and prevented new biofilms from forming, killing both planktonic bacteria and those within the biofilm. By enhancing oxidative cleavage of various substrates, the MNP-H2O2 system provides a novel strategy for biofilm elimination, and other applications utilizing oxidative breakdown.Hydrogen peroxide (H2O2) is a ``green chemical'' that has various cleaning and disinfectant uses, including as an anti-bacterial agent for hygienic and medical treatments. However, its efficacy is limited against biofilm-producing bacteria, because of poor penetration into the protective, organic matrix. Here we show new applications for ferromagnetic nanoparticles (Fe3O4, MNPs) with peroxidase-like activity in potentiating the efficacy of H2O2 in biofilm degradation and prevention. Our data show that MNPs enhanced oxidative cleavage of biofilm components (model nucleic acids, proteins, and oligosaccharides) in the presence of H2O2. When challenged with live, biofilm-producing bacteria, the MNP-H2O2 system efficiently broke down the existing biofilm and prevented new biofilms from forming, killing both planktonic bacteria and those within the biofilm. By enhancing oxidative cleavage of various substrates, the MNP-H2O2 system provides a novel

  5. Enhancement of Peroxidase Release from Non-Malignant and Malignant Cells through Low-Dose Irradiation with Different Radiation Quality.

    PubMed

    Abdelrazzak, Abdelrazek B; Pottgießer, Stefanie J; Hill, Mark A; O'Neill, Peter; Bauer, Georg

    2016-02-01

    The release of peroxidase by nontransformed or transformed fibroblasts or epithelial cells (effector cells) triggers apoptosis induction selectively in transformed fibroblasts or transformed epithelial cells (target cells) through intercellular apoptosis-inducing signaling. The release of peroxidase can be induced either by treatment with transforming growth factor beta 1 or by low doses of alpha particles, gamma rays or ultrasoft X rays. In addiation, data indicates that radiation quality does not determine the overall efficiency of peroxidase release and the effects among a wide range of radiation doses are indistinguishable. These findings suggested that peroxidase release might be being triggered through intercellular bystander signaling. We show here that maximal peroxidase release does indeed occur after coculture of a small number of irradiated cells with an excess of unirradiated cells and demonstrate an enhanced effector function of nontransformed cells after the addition of a small number of irradiated cells. These data strongly indicate that peroxidase release is indeed triggered through bystander signaling mechanisms in mammalian cells. PMID:26849404

  6. Roles of catalase and glutathione peroxidase in the tolerance of a pulmonate gastropod to anoxia and reoxygenation.

    PubMed

    Welker, Alexis F; Moreira, Daniel C; Hermes-Lima, Marcelo

    2016-07-01

    Humans and most mammals suffer severe damage when exposed to ischemia and reperfusion episodes due to an overproduction of reactive oxygen species (ROS). In contrast, several hypoxia/anoxia-tolerant animals survive very similar situations. We evaluated herein the redox metabolism in the anoxia-tolerant land snail Helix aspersa after catalase inhibition by 3-amino-1,2,4-triazole (ATZ) injection during a cycle of wide and abrupt change in oxygen availability. The exposure to anoxia for 5 h caused a change of only one of several parameters related to free radical metabolism: a rise in selenium-dependent glutathione peroxidase (Se-GPX) activity in muscle of both saline- and ATZ-injected animals (by 1.9- and 1.8-fold, respectively). Catalase suppression had no effect in animals under normoxia or anoxia. However, during reoxygenation catalase suppression kept high levels of muscle Se-GPX activity (twofold higher than in saline-injected snails up to 30 min reoxygenation) and induced the increase in hepatopancreas SOD activity (by 22 %), indicating higher levels of ROS in both organs than in saline-injected animals. Additionally, catalase-suppressed snails showed 12 % higher levels of carbonyl protein-a sign of mild oxidative stress-in muscle during reoxygenation than those animals with intact catalase. No changes were observed in glutathione parameters (GSH, GSSG and GSSG:GSH ratio), TBARS, and GST activity in any of the experimental groups, in both organs. These results indicate that catalase inhibition inflicts changes in the free radical metabolism during reoxygenation, prompting a stress-response that is a reorganization in other enzymatic antioxidant defenses to minimize alterations in the redox homeostasis in land snails. PMID:27062029

  7. Peroxidase-encapsulated cyclodextrin nanosponge immunoconjugates as a signal enhancement tool in optical and electrochemical assays.

    PubMed

    Wajs, Ewelina; Caldera, Fabrizio; Trotta, Francesco; Fragoso, Alex

    2014-01-21

    Cyclodextrin nanosponges bearing carboxylate groups have been prepared by crosslinking β-cyclodextrin with pyromellitic dianhydride to form a carboxylic acid terminated nanoporous material. The surface of the particles was covalently modified with an anti-IgG antibody and then loaded with horseradish peroxidase. The structures of unmodified and protein modified nanosponge particles were investigated by Raman spectroscopy and imaging methods. Confocal microscopy indicates that the antibody is located in the outside of the particle while HRP is encapsulated in the inner part. The possibility to use these modified nanosponges as a signal enhancement tool in enzyme-linked colorimetric and electrochemical assays was evaluated using a sandwich format comprising immobilised gliadin as an antigen, a target anti-gliadin antibody and an anti-IgG antibody conjugated to the enzyme-loaded nanosponge immunoconjugates. PMID:24276364

  8. Enhancement of reproductive heat tolerance in plants.

    PubMed

    Burke, John J; Chen, Junping

    2015-01-01

    Comparison of average crop yields with reported record yields has shown that major crops exhibit annual average yields three- to seven-fold lower than record yields because of unfavorable environments. The current study investigated the enhancement of pollen heat tolerance through expressing an Arabidopsis thaliana heat shock protein 101 (AtHSP101) that is not normally expressed in pollen but reported to play a crucial role in vegetative thermotolerance. The AtHSP101 construct under the control of the constitutive ocs/mas 'superpromoter' was transformed into cotton Coker 312 and tobacco SRI lines via Agrobacterium mediated transformation. Thermotolerance of pollen was evaluated by in vitro pollen germination studies. Comparing with those of wild type and transgenic null lines, pollen from AtHSP101 transgenic tobacco and cotton lines exhibited significantly higher germination rate and much greater pollen tube elongation under elevated temperatures or after a heat exposure. In addition, significant increases in boll set and seed numbers were also observed in transgenic cotton lines exposed to elevated day and night temperatures in both greenhouse and field studies. The results of this study suggest that enhancing heat tolerance of reproductive tissues in plant holds promise in the development of crops with improved yield production and yield sustainability in unfavorable environments. PMID:25849955

  9. Enhancement of Reproductive Heat Tolerance in Plants

    PubMed Central

    Burke, John J.; Chen, Junping

    2015-01-01

    Comparison of average crop yields with reported record yields has shown that major crops exhibit annual average yields three- to seven-fold lower than record yields because of unfavorable environments. The current study investigated the enhancement of pollen heat tolerance through expressing an Arabidopsis thaliana heat shock protein 101 (AtHSP101) that is not normally expressed in pollen but reported to play a crucial role in vegetative thermotolerance. The AtHSP101 construct under the control of the constitutive ocs/mas ‘superpromoter’ was transformed into cotton Coker 312 and tobacco SRI lines via Agrobacterium mediated transformation. Thermotolerance of pollen was evaluated by in vitro pollen germination studies. Comparing with those of wild type and transgenic null lines, pollen from AtHSP101 transgenic tobacco and cotton lines exhibited significantly higher germination rate and much greater pollen tube elongation under elevated temperatures or after a heat exposure. In addition, significant increases in boll set and seed numbers were also observed in transgenic cotton lines exposed to elevated day and night temperatures in both greenhouse and field studies. The results of this study suggest that enhancing heat tolerance of reproductive tissues in plant holds promise in the development of crops with improved yield production and yield sustainability in unfavorable environments. PMID:25849955

  10. Ferromagnetic nanoparticles with peroxidase-like activity enhance the cleavage of biological macromolecules for biofilm elimination

    PubMed Central

    Gao, Lizeng; Giglio, Krista M.; Nelson, Jacquelyn L.; Sondermann, Holger; Travis, Alexander J.

    2014-01-01

    Hydrogen peroxide (H2O2) is a “green chemical” that has various cleaning and disinfectant uses, including as an anti-bacterial agent for hygienic and medical treatments. However, its efficacy is limited against biofilm-producing bacteria, because of poor penetration of the protective, organic matrix. Here we show new applications for ferromagnetic nanoparticles (Fe3O4, MNP) with peroxidase-like activity in potentiating the efficacy of H2O2 in biofilm degradation and prevention. Our data show that MNP enhanced oxidative cleavage of biofilm components (model nucleic acids, proteins, and oligosaccharides) in the presence of H2O2. When challenged with live, biofilm-producing bacteria, the MNP-H2O2 system efficiently broke down existing biofilm and prevented new biofilm from forming, killing both planktonic bacteria and those within biofilm. By enhancing oxidative cleavage of various substrates, the MNP-H2O2 system provides a novel strategy for biofilm elimination, and other applications utilizing oxidative breakdown. PMID:24468900

  11. Genes Encoding Plant-Specific Class III Peroxidases Are Responsible for Increased Cold Tolerance of the brassinosteroid-insensitive 1 Mutant

    PubMed Central

    Kim, Beg Hab; Kim, Sun Young; Nam, Kyoung Hee

    2012-01-01

    We previously reported that one of the brassinosteroid-insensitive mutants, bri1-9, showed increased cold tolerance compared with both wild type and BRI1-overexpressing transgenic plants, despite its severe growth retardation. This increased tolerance in bri1-9 resulted from the constitutively high expression of stress-inducible genes under normal conditions. In this report, we focused on the genes encoding class III plant peroxidases (AtPrxs) because we found that, compared with wild type, bri1-9 plants contain higher levels of reactive oxygen species (ROS) that are not involved with the activation of NADPH oxidase and show an increased level of expression of a subset of genes encoding class III plant peroxidases. Treatment with a peroxidase inhibitor, salicylhydroxamic acid (SHAM), led to the reduction of cold resistance in bri1-9. Among 73 genes that encode AtPrxs in Arabidopsis, we selected four (AtPrx1, AtPrx22, AtPrx39, and AtPrx69) for further functional analyses in response to cold temperatures. T-DNA insertional knockout mutants showed increased sensitivity to cold stress as measured by leaf damage and ion leakage. In contrast, the overexpression of AtPrx22, AtPrx39, and AtPrx69 increased cold tolerance in the BRI1-GFP plants. Taken together, these results indicate that the appropriate expression of a particular subset of AtPrx genes and the resulting higher levels of ROS production are required for the cold tolerance. PMID:23180292

  12. Peroxidase-like activity of Fe3O4@carbon nanoparticles enhances ascorbic acid-induced oxidative stress and selective damage to PC-3 prostate cancer cells.

    PubMed

    An, Qiao; Sun, Chuanyu; Li, Dian; Xu, Ke; Guo, Jia; Wang, Changchun

    2013-12-26

    Ascorbic acid (AA) is capable of inhibiting cancer cell growth by perturbing the normal redox state of cells and causing toxic effects through the generation of abundant reactive-oxygen species (ROS). However, the clinical utility of AA at a tolerable dosage is plagued by a relatively low in vivo efficacy. This study describes the development of a peroxidase-like composite nanoparticle for use in an AA-mediated therapeutic strategy. On the basis of a high-throughput, one-pot solvothermal approach, Fe3O4@C nanoparticles (NPs) were synthesized and then modified with folic acid (FA) on the surface. Particular focus is concentrated on the assessment of peroxidase-like catalytic activity by a chromogenic reaction in the presence of H2O2. The carbon shell of Fe3O4@C NPs contains partially graphitized carbon and thus facilitates electron transfer in the catalytic decomposition of H2O2, leading to the production of highly reactive hydroxyl radicals. Along with magnetic responsiveness and receptor-binding specificity, the intrinsic peroxidase-like catalytic activity of Fe3O4@C-FA NPs pronouncedly promotes AA-induced oxidative stress in cancer cells and optimizes the ROS-mediated antineoplastic efficacy of exogenous AA. In vitro experiments using human prostate cancer PC-3 cells demonstrate that Fe3O4@C-FA NPs serve as a peroxidase mimic to create hydroxyl radicals from endogenous H2O2 that is yielded in response to exogenous AA via an oxidative stress process. The usage of a dual agent leads to the enhanced cytotoxicity of PC-3 cells, and, because of the synergistic effect of NPs, the administrated dosage of AA is reduced markedly. However, because normal cells (HEK 293T cells) appear to have a higher capacity to cope with additionally generated ROS than cancer cells, the NP-AA combination shows little damage in this case, proving that selective killing of cancer cells could be achieved owing to preferential accumulation of ROS in cancer cells. A possible ROS

  13. Monitoring Synaptic Vesicle Protein Sorting with Enhanced Horseradish Peroxidase in the Electron Microscope.

    PubMed

    Schikorski, Thomas

    2016-01-01

    Protein sorting is the fundamental cellular process that creates and maintains cell organelles and subcellular structures. The synaptic vesicle (SV) is a unique cell organelle that contains a plethora of specific SV proteins and its protein composition is crucial for its function. Thus understanding the mechanisms that sort proteins to SVs and other cell organelles is central to neuroscience and cell biology.While in the past protein sorting was studied in the fluorescence and confocal microscope, we here present a protocol that reveals SV protein trafficking and sorting in the electron microscope (EM). The protocol exploits tagging SV proteins with a new genetically encoded label for EM: enhanced horseradish peroxidase (eHRP). eHRP gained its high sensitivity through direct evolution of its catalytic activity and is detectable in the EM and LM after expression in neurons and other mammalian cells. The protocol describes the use of eHRP, labeling of SVs in cultured hippocampal neurons, and analysis via serial section reconstruction. PMID:27515091

  14. A Basic Helix-Loop-Helix Transcription Factor, PtrbHLH, of Poncirus trifoliata Confers Cold Tolerance and Modulates Peroxidase-Mediated Scavenging of Hydrogen Peroxide1[C][W

    PubMed Central

    Huang, Xiao-San; Wang, Wei; Zhang, Qian; Liu, Ji-Hong

    2013-01-01

    The basic helix-loop-helix (bHLH) transcription factors are involved in a variety of physiological processes. However, plant bHLHs functioning in cold tolerance and the underlying mechanisms remain poorly understood. Here, we report the identification and functional characterization of PtrbHLH isolated from trifoliate orange (Poncirus trifoliata). The transcript levels of PtrbHLH were up-regulated under various abiotic stresses, particularly cold. PtrbHLH was localized in the nucleus with transactivation activity. Overexpression of PtrbHLH in tobacco (Nicotiana tabacum) or lemon (Citrus limon) conferred enhanced tolerance to cold under chilling or freezing temperatures, whereas down-regulation of PtrbHLH in trifoliate orange by RNA interference (RNAi) resulted in elevated cold sensitivity. A range of stress-responsive genes was up-regulated or down-regulated in the transgenic lemon. Of special note, several peroxidase (POD) genes were induced after cold treatment. Compared with the wild type, POD activity was increased in the overexpression plants but decreased in the RNAi plants, which was inversely correlated with the hydrogen peroxide (H2O2) levels in the tested lines. Treatment of the transgenic tobacco plants with POD inhibitors elevated the H2O2 levels and greatly compromised their cold tolerance, while exogenous replenishment of POD enhanced cold tolerance of the RNAi line. In addition, transgenic tobacco and lemon plants were more tolerant to oxidative stresses. Yeast one-hybrid assay and transient expression analysis demonstrated that PtrbHLH could bind to the E-box elements in the promoter region of a POD gene. Taken together, these results demonstrate that PtrbHLH plays an important role in cold tolerance, at least in part, by positively regulating POD-mediated reactive oxygen species removal. PMID:23624854

  15. Transgenic Alfalfa Plants Expressing the Sweetpotato Orange Gene Exhibit Enhanced Abiotic Stress Tolerance

    PubMed Central

    Wang, Zhi; Ke, Qingbo; Kim, Myoung Duck; Kim, Sun Ha; Ji, Chang Yoon; Jeong, Jae Cheol; Lee, Haeng-Soon; Park, Woo Sung; Ahn, Mi-Jeong; Li, Hongbing; Xu, Bingcheng; Deng, Xiping; Lee, Sang-Hoon; Lim, Yong Pyo; Kwak, Sang-Soo

    2015-01-01

    Alfalfa (Medicago sativa L.), a perennial forage crop with high nutritional content, is widely distributed in various environments worldwide. We recently demonstrated that the sweetpotato Orange gene (IbOr) is involved in increasing carotenoid accumulation and enhancing resistance to multiple abiotic stresses. In this study, in an effort to improve the nutritional quality and environmental stress tolerance of alfalfa, we transferred the IbOr gene into alfalfa (cv. Xinjiang Daye) under the control of an oxidative stress-inducible peroxidase (SWPA2) promoter through Agrobacterium tumefaciens-mediated transformation. Among the 11 transgenic alfalfa lines (referred to as SOR plants), three lines (SOR2, SOR3, and SOR8) selected based on their IbOr transcript levels were examined for their tolerance to methyl viologen (MV)-induced oxidative stress in a leaf disc assay. The SOR plants exhibited less damage in response to MV-mediated oxidative stress and salt stress than non-transgenic plants. The SOR plants also exhibited enhanced tolerance to drought stress, along with higher total carotenoid levels. The results suggest that SOR alfalfa plants would be useful as forage crops with improved nutritional value and increased tolerance to multiple abiotic stresses, which would enhance the development of sustainable agriculture on marginal lands. PMID:25946429

  16. Enhanced oxidation of aniline derivatives by two mutants of cytochrome c peroxidase at tryptophan 51.

    PubMed

    Roe, J A; Goodin, D B

    1993-09-25

    Two hyperactive mutants of cytochrome c peroxidase (CCP), W51F and W51A, catalyze the enhanced oxidation of a number of substituted anilines. The reaction of CCP compound ES with mesidine is biphasic, while similar reactions using compound II give monophasic kinetics. These data, in addition to the ratio of the Fe4+ = O and free-radical species observed during steady-state turnover, indicate that reduction of the Trp-191 free radical of compound ES is more rapid than the reduction of the Fe4+ = O species. Transient kinetics were examined for the oxidation of eight mono-substituted anilines by CCP, W51F, and W51A. Each of the aniline derivatives were oxidized by the mutants at rates that exceeded that of the wild-type enzyme, and the rate constant for m-chloroaniline was 400-fold faster for W51F than for wild-type CCP. Variations in the rate constants for the different substrates follow a linear free-energy relationship using the Hammet substituent effect parameter sigma +, implicating electron transfer from the aniline ring in the transition state. For aniline oxidation, the free energy of activation is 3 kcal/mol lower for the mutants than for wild-type CCP, and this is due primarily to an increase in the activation entropy. These results indicate that the enhanced kinetics of W51F and W51A result from a generalized increase in enzyme reactivity characterized by an exo-entropic transition state such as dissociation of bound H2O from the Fe4+ = O center. PMID:8397197

  17. A redox-dependent dimerization switch regulates activity and tolerance for reactive oxygen species of barley seed glutathione peroxidase.

    PubMed

    Navrot, Nicolas; Skjoldager, Nicklas; Bunkenborg, Jakob; Svensson, Birte; Hägglund, Per

    2015-05-01

    Monomeric and dimeric forms of recombinant barley (Hordeum vulgare subsp. vulgare) glutathione peroxidase 2 (HvGpx2) are demonstrated to display distinctly different functional properties in vitro. Monomeric HvGpx2 thus has five fold higher catalytic efficiency than the dimer towards tert-butyl hydroperoxide, but is more sensitive to inactivation by hydrogen peroxide. Treatment of the monomer with hydrogen peroxide results in dimer formation. This observed new behavior of a plant glutathione peroxidase suggests a mechanism involving a switch from a highly catalytically competent monomer to a less active, but more oxidation-resistant dimer. PMID:25796076

  18. Redox Potential of Peroxidases

    NASA Astrophysics Data System (ADS)

    Ayala, Marcela

    Redox potential of peroxidases greatly influences the range of oxidizable substrates: in principle, peroxidases may only catalyze the oxidation of substrates with lower redox potential. There is substantial information on the factors that modulate the redox potential of heme proteins. Both theoretical and experimental evidence highlight the most significant contributions arising from the interaction of heme iron with the axial ligands, as well as the electrostatic interactions surrounding the heme group. However, for different proteins, the factors contribute to different extents. Understanding the electrochemistry of heme peroxidases is fundamental in order to design enhanced biocatalysts. In this chapter, current knowledge of the forces influencing redox potential of heme peroxidases is reviewed.

  19. Interprotein Coupling Enhances the Electrocatalytic Efficiency of Tobacco Peroxidase Immobilized at a Graphite Electrode.

    PubMed

    Olloqui-Sariego, José Luis; Zakharova, Galina S; Poloznikov, Andrey A; Calvente, Juan José; Hushpulian, Dmitry M; Gorton, Lo; Andreu, Rafael

    2015-11-01

    Covalent immobilization of enzymes at electrodes via amide bond formation is usually carried out by a two-step protocol, in which surface carboxylic groups are first activated with the corresponding cross-coupling reagents and then reacted with protein amine groups. Herein, it is shown that a modification of the above protocol, involving the simultaneous incubation of tobacco peroxidase and the pyrolytic graphite electrode with the cross-coupling reagents produces higher and more stable electrocatalytic currents than those obtained with either physically adsorbed enzymes or covalently immobilized enzymes according to the usual immobilization protocol. The remarkably improved electrocatalytic properties of the present peroxidase biosensor that operates in the 0.3 V ≤ E ≤ 0.8 V (vs SHE) potential range can be attributed to both an efficient electronic coupling between tobacco peroxidase and graphite and to the formation of intra- and intermolecular amide bonds that stabilize the protein structure and improve the percentage of anchoring groups that provide an adequate orientation for electron exchange with the electrode. The optimized tobacco peroxidase sensor exhibits a working concentration range of 10-900 μM, a sensitivity of 0.08 A M(-1) cm(-2) (RSD 0.05), a detection limit of 2 μM (RSD 0.09), and a good long-term stability, as long as it operates at low temperature. These parameter values are among the best reported so far for a peroxidase biosensor operating under simple direct electron transfer conditions. PMID:26437673

  20. Application of a Novel Alkali-Tolerant Thermostable DyP-Type Peroxidase from Saccharomonospora viridis DSM 43017 in Biobleaching of Eucalyptus Kraft Pulp

    PubMed Central

    Huang, Huoqing; Zheng, Fei; Wang, Xiaoyu; Wu, Yuying; Li, Kangjia; Xie, Xiangming; Jin, Yi

    2014-01-01

    Saccharomonospora viridis is a thermophilic actinomycete that may have biotechnological applications because of its dye decolorizing activity, though the enzymatic oxidative system responsible for this activity remains elusive. Bioinformatic analysis revealed a DyP-type peroxidase gene in the genome of S. viridis DSM 43017 with sequence similarity to peroxidase from dye-decolorizing microbes. This gene, svidyp, consists of 1,215 bp encoding a polypeptide of 404 amino acids. The gene encoding SviDyP was cloned, heterologously expressed in Escherichia coli, and then purified. The recombinant protein could efficiently decolorize several triarylmethane dyes, anthraquinonic and azo dyes under neutral to alkaline conditions. The optimum pH and temperature for SviDyP was pH 7.0 and 70°C, respectively. Compared with other DyP-type peroxidases, SviDyP was more active at high temperatures, retaining>63% of its maximum activity at 50–80°C. It also showed broad pH adaptability (>35% activity at pH 4.0–9.0) and alkali-tolerance (>80% activity after incubation at pH 5–10 for 1 h at 37°C), and was highly thermostable (>60% activity after incubation at 70°C for 2 h at pH 7.0). SviDyP had an accelerated action during the biobleaching of eucalyptus kraft pulp, resulting in a 21.8% reduction in kappa number and an increase of 2.98% (ISO) in brightness. These favorable properties make SviDyP peroxidase a promising enzyme for use in the pulp and paper industries. PMID:25333297

  1. Effective Synergistic Effect of Dipeptide-Polyoxometalate-Graphene Oxide Ternary Hybrid Materials on Peroxidase-like Mimics with Enhanced Performance.

    PubMed

    Ma, Zhuo; Qiu, Yunfeng; Yang, Huihui; Huang, Yanmin; Liu, Jingjing; Lu, Yue; Zhang, Chen; Hu, PingAn

    2015-10-01

    Dipeptide-polyoxometalates (POMs)-graphene oxide (GO) ternary hybrid is an excellent peroxidase-like mimic, exhibiting enhanced peroxidase-like activity compared to POMs alone. The hybrid was readily prepared through a reprecipitation method involving electrostatic encapsulation of H3PW12O40 (PW12) by cationic diphenylalanine (FF) peptide and coassembly of FF@PW12 spheres with graphene oxide (GO). Using 3,3',5,5'-tetramethylbenzidine (TMB) as the chromogenic substrate, the peroxidase-like activity of FF@PW12 was evaluated in the heterogeneous phase, and it is 13 times higher than that of pristine PW12 in the homogeneous phase. Furthermore, ternary hybrids of FF@PW12@GO containing 5 wt % GO could enhance the activity 1.7 times higher than that of FF@PW12. The noncovalent interactions of hydrogen bonding and ionic interaction between GO and POMs are speculated to result in the synergistic effect for the enhancement of peroxidase-like performance. The strong interactions between rGO and PW12 are evaluated by a four-probe Hall measurement via the van der Pauw method, and rGO is significantly p-doped by the doping effect of PW12 with lower LUMO energy than that of the energy level of rGO and also due to the electron reservoir feature of PW12. Cyclic voltammogram measurements also suggest that GO causes significant influence on the electronic structure of the reduced forms of the redox couples of PW12. The nature of the TMB catalytic reaction may originate from the generation of the hydroxyl radical ((•)OH) from the decomposition of H2O2 by ternary hybrids and the formation of peroxo species of POM. Taking advantage of the UV-vis signals of TMB being correlated to the concentration of H2O2, FF@PW12@GO can be used to detect H2O2 within the limit of detection of 0.11 μM, and the detection range is 1-75 μM. The present method indeed opens up a promising route in constructing heterogeneous peroxidase-like mimics through the use of POMs via the introduction of GO for

  2. Naked-eye sensitive ELISA-like assay based on gold-enhanced peroxidase-like immunogold activity.

    PubMed

    Wang, Shasha; Chen, Zhaopeng; Choo, Jaebum; Chen, Lingxin

    2016-02-01

    A naked-eye sensitive ELISA-like assay was developed based on gold-enhanced peroxidase-like activity of gold nanoparticles (AuNPs). Using human IgG (H-IgG) as an analytical model, goat anti-human IgG antibody (anti-IgG) adsorbed on microtiter plate and AuNPs-labeled anti-IgG acted as capture antibody and detection antibody, respectively. Because the surfaces of AuNPs were blocked by protein molecules, the peroxidase-like activity of AuNPs was almost inhibited, evaluated by the catalytic oxidation of peroxidase enzyme substrate 3,3',5,5'-tetramethylbenzidine (TMB), which could produce a bright blue color in the presence of H2O2. Fortunately, the catalytic ability of AuNPs was dramatically increased by the deposition of gold due to the formation of a new gold shell on immunogold. Under optimal reaction conditions, the colorimetric immunoassay presented a good linear relationship in the range of 0.7-100 ng/mL and the limit of detection (LOD) of 0.3 ng/mL calculated by 3σ/S for UV-vis detection, and obtained LOD of 5 ng/mL for naked-eye detection. The obtained results were competitive with conventional sandwich ELISA with the LOD of 1.6 ng/mL. Furthermore, this developed colorimetric immunoassay was successfully applied to diluted human serum and fetal bovine serum samples, and predicted a broad prospect for the use of peroxidase-like activity involving nanomaterials in bioassay and diagnostics. PMID:26677026

  3. Microorganisms having enhanced tolerance to inhibitors and stress

    DOEpatents

    Brown, Steven D.; Yang, Shihui

    2014-07-29

    The present invention provides genetically modified strains of microorganisms that display enhanced tolerance to stress and/or inhibitors such as sodium acetate and vanillin. The enhanced tolerance can be achieved by increasing the expression of a protein of the Sm-like superfamily such as a bacterial Hfq protein and a fungal Sm or Lsm protein. Further, the present invention provides methods of producing alcohol from biomass materials by using the genetically modified microorganisms of the present invention.

  4. Immobilization of peroxidase enzyme onto the porous silicon structure for enhancing its activity and stability

    NASA Astrophysics Data System (ADS)

    Sahare, Padmavati; Ayala, Marcela; Vazquez-Duhalt, Rafael; Agrawal, Vivechana

    2014-08-01

    In this work, a commercial peroxidase was immobilized onto porous silicon (PS) support functionalized with 3-aminopropyldiethoxysilane (APDES) and the performance of the obtained catalytic microreactor was studied. The immobilization steps were monitored and the activity of the immobilized enzyme in the PS pores was spectrophotometrically determined. The enzyme immobilization in porous silicon has demonstrated its potential as highly efficient enzymatic reactor. The effect of a polar organic solvent (acetonitrile) and the temperature (up to 50°C) on the activity and stability of the biocatalytic microreactor were studied. After 2-h incubation in organic solvent, the microreactor retained 80% of its initial activity in contrast to the system with free soluble peroxidase that lost 95% of its activity in the same period of time. Peroxidase immobilized into the spaces of the porous silicon support would be perspective for applications in treatments for environmental security such as removal of leached dye in textile industry or in treatment of different industrial effluents. The system can be also applied in the field of biomedicine.

  5. Immobilization of peroxidase enzyme onto the porous silicon structure for enhancing its activity and stability

    PubMed Central

    2014-01-01

    In this work, a commercial peroxidase was immobilized onto porous silicon (PS) support functionalized with 3-aminopropyldiethoxysilane (APDES) and the performance of the obtained catalytic microreactor was studied. The immobilization steps were monitored and the activity of the immobilized enzyme in the PS pores was spectrophotometrically determined. The enzyme immobilization in porous silicon has demonstrated its potential as highly efficient enzymatic reactor. The effect of a polar organic solvent (acetonitrile) and the temperature (up to 50°C) on the activity and stability of the biocatalytic microreactor were studied. After 2-h incubation in organic solvent, the microreactor retained 80% of its initial activity in contrast to the system with free soluble peroxidase that lost 95% of its activity in the same period of time. Peroxidase immobilized into the spaces of the porous silicon support would be perspective for applications in treatments for environmental security such as removal of leached dye in textile industry or in treatment of different industrial effluents. The system can be also applied in the field of biomedicine. PMID:25221454

  6. The Miscanthus NAC transcription factor MlNAC9 enhances abiotic stress tolerance in transgenic Arabidopsis.

    PubMed

    Zhao, Xun; Yang, Xuanwen; Pei, Shengqiang; He, Guo; Wang, Xiaoyu; Tang, Qi; Jia, Chunlin; Lu, Ying; Hu, Ruibo; Zhou, Gongke

    2016-07-15

    NAC (NAM, ATAF1/2, and CUC2) transcription factors are known to play important roles in responses to abiotic stresses in plants. Currently, little information regarding the functional roles of NAC genes in stress tolerance is available in Miscanthus lutarioriparius, a promising bioenergy plant for cellulosic ethanol production. In this study, we carried out the functional characterization of MlNAC9 in abiotic stresses. MlNAC9 was shown to act as a nuclear localized transcription activator with the activation domain in its C-terminus. The overexpression of MlNAC9 in Arabidopsis conferred hypersensitivity to abscisic acid (ABA) at seed germination and root elongation stages. In addition, the overexpression of MlNAC9 led to increased seed germination rate and root growth under salt (NaCl) treatment. Meanwhile, the transgenic Arabidopsis overexpressing MlNAC9 showed enhanced tolerance to drought and cold stresses. The expression of stress-responsive marker genes was significantly increased in MlNAC9 overexpression lines compared to that of WT under ABA, drought, salt, and cold stresses. Correspondingly, the activities of antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were significantly increased and the malondialdehyde (MDA) content was lower accumulated in MlNAC9 overexpression lines under drought and salt treatments. These results indicated that the overexpression of MlNAC9 improved the tolerance to abiotic stresses via an ABA-dependent pathway, and the enhanced tolerance of transgenic plants was mainly attributed to the increased expression of stress-responsive genes and the enhanced scavenging capability of reactive oxygen species (ROS). PMID:27085481

  7. Platinum nanocatalysts loaded on graphene oxide-dispersed carbon nanotubes with greatly enhanced peroxidase-like catalysis and electrocatalysis activities

    NASA Astrophysics Data System (ADS)

    Wang, Hua; Li, Shuai; Si, Yanmei; Zhang, Ning; Sun, Zongzhao; Wu, Hong; Lin, Yuehe

    2014-06-01

    A powerful enzymatic mimetic has been fabricated by employing graphene oxide (GO) nanocolloids to disperse conductive carbon supports of hydrophobic carbon nanotubes (CNTs) before and after the loading of Pt nanocatalysts. The resulting GOCNT-Pt nanocomposites could present improved aqueous dispersion stability and Pt spatial distribution. Unexpectedly, they could show greatly enhanced peroxidase-like catalysis and electrocatalysis activities in water, as evidenced in the colorimetric and electrochemical investigations in comparison to some inorganic nanocatalysts commonly used. Moreover, it is found that the new enzyme mimetics could exhibit peroxidase-like catalysis activity comparable to natural enzymes; yet, they might circumvent some of their inherent problems in terms of catalysis efficiency, electron transfer, environmental stability, and cost effectiveness. Also, sandwiched electrochemical immunoassays have been successfully conducted using GOCNT-Pt as enzymatic tags. Such a fabrication avenue of noble metal nanocatalysts loaded on well-dispersed conductive carbon supports should be tailored for the design of different enzyme mimics promising the extensive catalysis applications in environmental, medical, industrial, and particularly aqueous biosensing fields.A powerful enzymatic mimetic has been fabricated by employing graphene oxide (GO) nanocolloids to disperse conductive carbon supports of hydrophobic carbon nanotubes (CNTs) before and after the loading of Pt nanocatalysts. The resulting GOCNT-Pt nanocomposites could present improved aqueous dispersion stability and Pt spatial distribution. Unexpectedly, they could show greatly enhanced peroxidase-like catalysis and electrocatalysis activities in water, as evidenced in the colorimetric and electrochemical investigations in comparison to some inorganic nanocatalysts commonly used. Moreover, it is found that the new enzyme mimetics could exhibit peroxidase-like catalysis activity comparable to natural

  8. Magnesium Deficiency and High Light Intensity Enhance Activities of Superoxide Dismutase, Ascorbate Peroxidase, and Glutathione Reductase in Bean Leaves 1

    PubMed Central

    Cakmak, Ismail; Marschner, Horst

    1992-01-01

    The influence of varied Mg supply (10-1000 micromolar) and light intensity (100-580 microeinsteins per square meter per second) on the concentrations of ascorbate (AsA) and nonprotein SH-compounds and the activities of superoxide dismutase (SOD; EC 1.15.11) and the H2O2 scavenging enzymes, AsA peroxidase (EC 1.11.1.7), dehydroascorbate reductase (EC 1.8.5.1), and glutathione reductase (EC 1.6.4.2) were studied in bean (Phaseolus vulgaris L.) leaves over a 13-day period. The concentrations of AsA and SH-compounds and the activities of SOD and H2O2 scavenging enzymes increased with light intensity, in particular in Mg-deficient leaves. Over the 12-day period of growth for a given light intensity, the concentrations of AsA and SH-compounds and the activities of these enzymes remained more or less constant in Mg-sufficient leaves. In contrast, in Mg-deficient leaves, a progressive increase was recorded, particularly in concentrations of AsA and activities of AsA peroxidase and glutathione reductase, whereas the activities of guaiacol peroxidase and catalase were only slightly enhanced. Partial shading of Mg-deficient leaf blades for 4 days prevented chlorosis, and the activities of the O2.− and H2O2 scavenging enzymes remained at a low level. The results demonstrate the role of both light intensity and Mg nutritional status on the regulation of O2.− and H2O2 scavenging enzymes in chloroplasts. PMID:16668779

  9. Ectopic over-expression of peroxisomal ascorbate peroxidase (SbpAPX) gene confers salt stress tolerance in transgenic peanut (Arachis hypogaea).

    PubMed

    Singh, Natwar; Mishra, Avinash; Jha, Bhavanath

    2014-08-15

    Peroxisomal ascorbate peroxidase gene (SbpAPX) of an extreme halophyte Salicornia brachiata imparts abiotic stress endurance and plays a key role in the protection against oxidative stress. The cloned SbpAPX gene was transformed to local variety of peanut and about 100 transgenic plants were developed using optimized in vitro regeneration and Agrobacterium mediated genetic transformation method. The T0 transgenic plants were confirmed for the gene integration; grown under controlled condition in containment green house facility; seeds were harvested and T1 plants were raised. Transgenic plants (T1) were further confirmed by PCR using gene specific primers and histochemical GUS assay. About 40 transgenic plants (T1) were selected randomly and subjected for salt stress tolerance study. Transgenic plants remained green however non-transgenic plants showed bleaching and yellowish leaves under salt stress conditions. Under stress condition, transgenic plants continued normal growth and completed their life cycle. Transgenic peanut plants exhibited adequate tolerance under salt stress condition and thus could be explored for the cultivation in salt affected areas for the sustainable agriculture. PMID:24954532

  10. Physiological integration enhanced the tolerance of Cynodon dactylon to flooding.

    PubMed

    Li, Z J; Fan, D Y; Chen, F Q; Yuan, Q Y; Chow, W S; Xie, Z Q

    2015-03-01

    Many flooding-tolerant species are clonal plants; however, the effects of physiological integration on plant responses to flooding have received limited attention. We hypothesise that flooding can trigger changes in metabolism of carbohydrates and ROS (reactive oxygen species) in clonal plants, and that physiological integration can ameliorate the adverse effects of stress, subsequently restoring the growth of flooded ramets. In the present study, we conducted a factorial experiment combining flooding to apical ramets and stolon severing (preventing physiological integration) between apical and basal ramets of Cynodon dactylon, which is a stoloniferous perennial grass with considerable flooding tolerance. Flooding-induced responses including decreased root biomass, accumulation of soluble sugar and starch, as well as increased activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in apical ramets. Physiological integration relieved growth inhibition, carbohydrate accumulation and induction of antioxidant enzyme activity in stressed ramets, as expected, without any observable cost in unstressed ramets. We speculate that relief of flooding stress in clonal plants may rely on oxidising power and electron acceptors transferred between ramets through physiological integration. PMID:25557716

  11. Two wheat glutathione peroxidase genes whose products are located in chloroplasts improve salt and H2O2 tolerances in Arabidopsis.

    PubMed

    Zhai, Chao-Zeng; Zhao, Lei; Yin, Li-Juan; Chen, Ming; Wang, Qing-Yu; Li, Lian-Cheng; Xu, Zhao-Shi; Ma, You-Zhi

    2013-01-01

    Oxidative stress caused by accumulation of reactive oxygen species (ROS) is capable of damaging effects on numerous cellular components. Glutathione peroxidases (GPXs, EC 1.11.1.9) are key enzymes of the antioxidant network in plants. In this study, W69 and W106, two putative GPX genes, were obtained by de novo transcriptome sequencing of salt-treated wheat (Triticum aestivum) seedlings. The purified His-tag fusion proteins of W69 and W106 reduced H2O2 and t-butyl hydroperoxide (t-BHP) using glutathione (GSH) or thioredoxin (Trx) as an electron donor in vitro, showing their peroxidase activity toward H2O2 and toxic organic hydroperoxide. GFP fluorescence assays revealed that W69 and W106 are localized in chloroplasts. Quantitative real-time PCR (Q-RT-PCR) analysis showed that two GPXs were differentially responsive to salt, drought, H2O2, or ABA. Isolation of the W69 and W106 promoters revealed some cis-acting elements responding to abiotic stresses. Overexpression of W69 and W106 conferred strong tolerance to salt, H2O2, and ABA treatment in Arabidopsis. Moreover, the expression levels of key regulator genes (SOS1, RbohD and ABI1/ABI2) involved in salt, H2O2 and ABA signaling were altered in the transgenic plants. These findings suggest that W69 and W106 not only act as scavengers of H2O2 in controlling abiotic stress responses, but also play important roles in salt and ABA signaling. PMID:24098330

  12. Enhanced chemiluminescence of CdTe quantum dots-H2O2 by horseradish peroxidase-mimicking DNAzyme

    NASA Astrophysics Data System (ADS)

    Zhang, Junli; Li, Baoxin

    In this study, it was found that horseradish peroxidase (HRP)-mimicking DNAzyme could effectively enhance the CL emission of CdTe quantum dots (QDs)-H2O2 system, whereas HRP could not enhance the CL intensity. The CL enhancement mechanism was investigated, and the CL enhancement was supposed to originate from the catalysis of HRP-mimicking DNAzyme on the CL reaction between CdTe QDs and H2O2. Meantime, compared with CdTe QDs-H2O2 CL system, H2O2 concentration was markedly decreased in QDs-H2O2-HRP-mimicking DNAzyme CL system, improving the stability of QDs-H2O2 CL system. The QDs-based CL system was used to detect sensitively CdTe QDs and HRP-mimicking DNAzyme (as biologic labels). This work gives a path for enhancing CL efficiency of QDs system, and will be helpful to promote the step of QDs application in various fields such as bioassay and trace detection of analyte.

  13. Enhanced chemiluminescence of CdTe quantum dots-H₂O₂ by horseradish peroxidase-mimicking DNAzyme.

    PubMed

    Zhang, Junli; Li, Baoxin

    2014-05-01

    In this study, it was found that horseradish peroxidase (HRP)-mimicking DNAzyme could effectively enhance the CL emission of CdTe quantum dots (QDs)-H2O2 system, whereas HRP could not enhance the CL intensity. The CL enhancement mechanism was investigated, and the CL enhancement was supposed to originate from the catalysis of HRP-mimicking DNAzyme on the CL reaction between CdTe QDs and H2O2. Meantime, compared with CdTe QDs-H2O2 CL system, H2O2 concentration was markedly decreased in QDs-H2O2-HRP-mimicking DNAzyme CL system, improving the stability of QDs-H2O2 CL system. The QDs-based CL system was used to detect sensitively CdTe QDs and HRP-mimicking DNAzyme (as biologic labels). This work gives a path for enhancing CL efficiency of QDs system, and will be helpful to promote the step of QDs application in various fields such as bioassay and trace detection of analyte. PMID:24556131

  14. Self-enhanced N-(aminobutyl)-N-(ethylisoluminol) derivative-based electrochemiluminescence immunosensor for sensitive laminin detection using PdIr cubes as a mimic peroxidase

    NASA Astrophysics Data System (ADS)

    Jiang, Xinya; Wang, Huijun; Wang, Haijun; Zhuo, Ying; Yuan, Ruo; Chai, Yaqin

    2016-04-01

    Herein, a self-enhanced N-(aminobutyl)-N-(ethylisoluminol) (ABEI) derivative-based electrochemiluminescence (ECL) immunosensor was constructed for the determination of laminin (LN) using PdIr cubes as a mimic peroxidase for signal amplification. Initially, PdIr cubes with efficient peroxidase mimicking properties, large specific surface areas, and good stability and uniformity were synthesized. Then, l-cysteine (l-Cys) and ABEI were immobilized on the PdIr cubes to form the self-enhanced ECL nanocomplex (PdIr-l-Cys-ABEI). In this nanocomplex, PdIr cubes, whose catalytic constant is higher than that of horseradish peroxidase (HRP), could effectively catalyze H2O2 decomposition and thus enhance the ECL intensity of ABEI. Moreover, PdIr cubes can be easily modified with functional groups, which make them adaptable to desired supported platforms. On the other hand, l-Cys as a coreactant of ABEI could effectively enhance the luminous efficiency due to the intramolecular ECL reaction which could reduce the energy loss between l-Cys and ABEI by giving a shorter electron transfer distance. The developed strategy combined an ABEI derivative as a self-enhanced ECL luminophore and PdIr cubes as a mimic peroxidase, resulting in a significantly enhanced ECL signal output. Also, the strategy showed high sensitivity and selectivity for LN, which suggested that our new approach could be potentially applied in monitoring different proteins.

  15. Emmental Cheese Environment Enhances Propionibacterium freudenreichii Stress Tolerance.

    PubMed

    Gagnaire, Valérie; Jardin, Julien; Rabah, Houem; Briard-Bion, Valérie; Jan, Gwénaël

    2015-01-01

    Dairy propionibacteria are actinomycetales found in various fermented food products. The main species, Propionibacterium freudenreichii, is generally recognized as safe and used both as probiotic and as cheese starter. Its probiotic efficacy tightly depends on its tolerance towards digestive stresses, which can be largely modulated by the ingested delivery vehicle. Indeed, tolerance of this bacterium is enhanced when it is consumed within a fermented dairy product, compared to a dried probiotic preparation. We investigated both stress tolerance and protein neosynthesis upon growth in i) chemically defined or ii) aqueous phase of Emmental cheeses. Although the same final population level was reached in both media, a slower growth and an enhanced survival of CIRM BIA 1 strain of P. freudenreichii subsp. shermanii was observed in Emmental juice, compared to chemically defined medium. This was accompanied by differences in substrates used and products released as well as overexpression of various early stress adaptation proteins in Emmental juice, compared to chemically defined medium, implied in protein folding, in aspartate catabolism, in biosynthesis of valine, leucine and isoleucine, in pyruvate metabolism in citrate cycle, in the propionate metabolism, as well as in oxidoreductases. All these changes led to a higher digestive stress tolerance after growth in Emmental juice. Mechanisms of stress adaptation were induced in this environment, in accordance with enhanced survival. This opens perspectives for the use of hard and semi-hard cheeses as delivery vehicle for probiotics with enhanced efficacy. PMID:26275229

  16. Emmental Cheese Environment Enhances Propionibacterium freudenreichii Stress Tolerance

    PubMed Central

    Gagnaire, Valérie; Jardin, Julien; Rabah, Houem; Briard-Bion, Valérie; Jan, Gwénaël

    2015-01-01

    Dairy propionibacteria are actinomycetales found in various fermented food products. The main species, Propionibacterium freudenreichii, is generally recognized as safe and used both as probiotic and as cheese starter. Its probiotic efficacy tightly depends on its tolerance towards digestive stresses, which can be largely modulated by the ingested delivery vehicle. Indeed, tolerance of this bacterium is enhanced when it is consumed within a fermented dairy product, compared to a dried probiotic preparation. We investigated both stress tolerance and protein neosynthesis upon growth in i) chemically defined or ii) aqueous phase of Emmental cheeses. Although the same final population level was reached in both media, a slower growth and an enhanced survival of CIRM BIA 1 strain of P. freudenreichii subsp. shermanii was observed in Emmental juice, compared to chemically defined medium. This was accompanied by differences in substrates used and products released as well as overexpression of various early stress adaptation proteins in Emmental juice, compared to chemically defined medium, implied in protein folding, in aspartate catabolism, in biosynthesis of valine, leucine and isoleucine, in pyruvate metabolism in citrate cycle, in the propionate metabolism, as well as in oxidoreductases. All these changes led to a higher digestive stress tolerance after growth in Emmental juice. Mechanisms of stress adaptation were induced in this environment, in accordance with enhanced survival. This opens perspectives for the use of hard and semi-hard cheeses as delivery vehicle for probiotics with enhanced efficacy. PMID:26275229

  17. Enhanced Fault-Tolerant Quantum Computing in d -Level Systems

    NASA Astrophysics Data System (ADS)

    Campbell, Earl T.

    2014-12-01

    Error-correcting codes protect quantum information and form the basis of fault-tolerant quantum computing. Leading proposals for fault-tolerant quantum computation require codes with an exceedingly rare property, a transversal non-Clifford gate. Codes with the desired property are presented for d -level qudit systems with prime d . The codes use n =d -1 qudits and can detect up to ˜d /3 errors. We quantify the performance of these codes for one approach to quantum computation known as magic-state distillation. Unlike prior work, we find performance is always enhanced by increasing d .

  18. Ultrathin graphitic carbon nitride nanosheets: a novel peroxidase mimetic, Fe doping-mediated catalytic performance enhancement and application to rapid, highly sensitive optical detection of glucose.

    PubMed

    Tian, Jingqi; Liu, Qian; Asiri, Abdullah M; Qusti, Abdullah H; Al-Youbi, Abdulrahman O; Sun, Xuping

    2013-12-01

    In this article, we demonstrate for the first time that ultrathin graphitic carbon nitride nanosheets (g-C3N4) possess peroxidase activity. Fe doping of the nanosheets leads to peroxidase mimetics with greatly enhanced catalytic performance and the mechanism involved is proposed. We further demonstrate the novel use of such Fe-g-C3N4 as a cheap nanosensor for simple, rapid, highly selective and sensitive optical detection of glucose with a pretty low detection limit of 0.5 μM. PMID:24121798

  19. Cooperation enhanced by moderate tolerance ranges in myopically selective interactions

    NASA Astrophysics Data System (ADS)

    Chen, Xiaojie; Wang, Long

    2009-10-01

    We present a mode of myopically selective interaction to study the evolutionary prisoner’s dilemma game in scale-free networks. Each individual has a reputation-based tolerance range and only tends to interact with the neighbors whose reputation is within its tolerance range. Moreover, its reputation is assessed in response to the interactions in the neighborhood. Interestingly, we show that moderate values of tolerance range can result in the best promotion of cooperation due to the emergence of group selection mechanism. Furthermore, we study the effects of weighting factor in the assessment rule of reputation on the evolution of cooperation. We also show how cooperation evolves in some extended situations, where an interaction stimulus payment is considered for individuals, and where the strategy and reputation of individuals can spread simultaneously. Our results may enhance the understanding of evolutionary dynamics in graph-structured populations where individuals conditionally play with their neighbors according to some myopic selection criteria.

  20. Factors Affecting the Enhancement of Oxidative Stress Tolerance in Transgenic Tobacco Overexpressing Manganese Superoxide Dismutase in the Chloroplasts.

    PubMed Central

    Slooten, L.; Capiau, K.; Van Camp, W.; Van Montagu, M.; Sybesma, C.; Inze, D.

    1995-01-01

    Two varieties of tobacco (Nicotiana tabacum var PBD6 and var SR1) were used to generate transgenic lines overexpressing Mn-superoxide dismutase (MnSOD) in the chloroplasts. The overexpressed MnSOD suppresses the activity of those SODs (endogenous MnSOD and chloroplastic and cytosolic Cu/ZnSOD) that are prominent in young leaves but disappear largely or completely during aging of the leaves. The transgenic and control plants were grown at different light intensities and were then assayed for oxygen radical stress tolerance in leaf disc assays and for abundance of antioxidant enzymes and substrates in leaves. Transgenic plants had an enhanced resistance to methylviologen (MV), compared with control plants, only after growth at high light intensities. In both varieties the activities of FeSOD, ascorbate peroxidase, dehydroascorbate reductase, and monodehydroascorbate reductase and the concentrations of glutathione and ascorbate (all expressed on a chlorophyll basis) increased with increasing light intensity during growth. Most of these components were correlated with MV tolerance. It is argued that SOD overexpression leads to enhancement of the tolerance to MV-dependent oxidative stress only if one or more of these components is also present at high levels. Furthermore, the results suggest that in var SR1 the overexpressed MnSOD enhances primarily the stromal antioxidant system. PMID:12228398

  1. Polyacrylamide Gel-Entrapped Fungal Manganese Peroxidase from Ganoderma lucidum IBL-05 with Enhanced Catalytic, Stability, and Reusability Characteristics.

    PubMed

    Bilal, Muhammad; Asgher, Muhammad; Iqbal, Hafiz M N

    2016-01-01

    In the present study, polyacrylamide gel (PAG) was utilized as bolster material for the immobilization of in-house extracted and partially purified manganese peroxidase (MnP) through an entrapment technique yielding significant MnP immobilization (87.3±3.3 %) and remarkable stability of the enzyme (37.2±2.4 %) after a storage period of two months at 4°C. The immobilization also increased the optimal temperature by 10 °C and provided an alkaline shift of the pH optimum. Moreover, a significant enhancement in the thermo-stability was observed. After an incubation period of 72 h at 50°C, the PAG-entrapped-MnP still exhibited 41.2 % of the initial activity, whereas the free enzyme was completely inactive. Furthermore, PAG-entrapped-MnP showed an excellent recycling efficiency and retained more than 50% of its initial activity after five consecutive reaction cycles. In conclusion, owing to the economic feasibility, carrier-supported MnP may be a promising candidate for various applications in different industrial sectors. PMID:27531237

  2. Release of Pleurotus ostreatus Versatile-Peroxidase from Mn2+ Repression Enhances Anthropogenic and Natural Substrate Degradation

    PubMed Central

    Salame, Tomer M.; Knop, Doriv; Levinson, Dana; Mabjeesh, Sameer J.; Yarden, Oded; Hadar, Yitzhak

    2012-01-01

    The versatile-peroxidase (VP) encoded by mnp4 is one of the nine members of the manganese-peroxidase (MnP) gene family that constitutes part of the ligninolytic system of the white-rot basidiomycete Pleurotus ostreatus (oyster mushroom). VP enzymes exhibit dual activity on a wide range of substrates. As Mn2+ supplement to P. ostreatus cultures results in enhanced degradation of recalcitrant compounds and lignin, we examined the effect of Mn2+ on the expression profile of the MnP gene family. In P. ostreatus (monokaryon PC9), mnp4 was found to be the predominantly expressed mnp in Mn2+-deficient media, whereas strongly repressed (to approximately 1%) in Mn2+-supplemented media. Accordingly, in-vitro Mn2+-independent activity was found to be negligible. We tested whether release of mnp4 from Mn2+ repression alters the activity of the ligninolytic system. A transformant over-expressing mnp4 (designated OEmnp4) under the control of the β-tubulin promoter was produced. Now, despite the presence of Mn2+ in the medium, OEmnp4 produced mnp4 transcript as well as VP activity as early as 4 days after inoculation. The level of expression was constant throughout 10 days of incubation (about 0.4-fold relative to β-tubulin) and the activity was comparable to the typical activity of PC9 in Mn2+-deficient media. In-vivo decolorization of the azo dyes Orange II, Reactive Black 5, and Amaranth by OEmnp4 preceded that of PC9. OEmnp4 and PC9 were grown for 2 weeks under solid-state fermentation conditions on cotton stalks as a lignocellulosic substrate. [14C]-lignin mineralization, in-vitro dry matter digestibility, and neutral detergent fiber digestibility were found to be significantly higher (about 25%) in OEmnp4-fermented substrate, relative to PC9. We conclude that releasing Mn2+ suppression of VP4 by over-expression of the mnp4 gene in P. ostreatus improved its ligninolytic functionality. PMID:23285046

  3. Enhanced Accident Tolerant LWR Fuels National Metrics Workshop Report

    SciTech Connect

    Lori Braase

    2013-01-01

    The U.S. Department of Energy Office of Nuclear Energy (DOE-NE), in collaboration with the nuclear industry, has been conducting research and development (R&D) activities on advanced Light Water Reactor (LWR) fuels for the last few years. The emphasis for these activities was on improving the fuel performance in terms of increased burnup for waste minimization and increased power density for power upgrades, as well as collaborating with industry on fuel reliability. After the events at the Fukushima Nuclear Power Plant in Japan in March 2011, enhancing the accident tolerance of LWRs became a topic of serious discussion. In the Consolidated Appropriations Act, 2012, Conference Report 112-75, the U.S. Congress directed DOE-NE to: • Give “priority to developing enhanced fuels and cladding for light water reactors to improve safety in the event of accidents in the reactor or spent fuel pools.” • Give “special technical emphasis and funding priority…to activities aimed at the development and near-term qualification of meltdown-resistant, accident-tolerant nuclear fuels that would enhance the safety of present and future generations of light water reactors.” • Report “to the Committee, within 90 days of enactment of this act, on its plan for development of meltdown-resistant fuels leading to reactor testing and utilization by 2020.” Fuels with enhanced accident tolerance are those that, in comparison with the standard UO2-zirconium alloy system currently used by the nuclear industry, can tolerate loss of active cooling in the reactor core for a considerably longer time period (depending on the LWR system and accident scenario) while maintaining or improving the fuel performance during normal operations, and operational transients, as well as design-basis and beyond design-basis events. The overall draft strategy for development and demonstration is comprised of three phases: Feasibility Assessment and Down-selection; Development and Qualification; and

  4. Enhanced performance of the aerobic landfill reactor by augmentation of manganese peroxidase.

    PubMed

    Bartholameuz, E M; Hettiaratchi, J P A; Kumar, S

    2016-10-01

    The aim of the work discussed in this article was to determine the ability of an MnP augmented aerobic waste cell to reach stable conditions rapidly in terms of gas production, nutrient content and cellulose and hemicellulose to lignin ratio (C+H/L). Two types of experiments were conducted; small batch and laboratory scale lysimeter experiments. Results from batch experiments showed that enzyme added treatments have the capability to reach a stable C+H/L and lower gas production rates, faster than the treatments without enzyme addition. Enzyme enhancement of the lysimeter increased the rate of biodegradability of the waste; gas production increased more than two times and there was clear evidence of increase in nutrients (nitrogen, dissolved carbon, biological oxygen demand) in the lysimeter ​leachate. PMID:27347797

  5. Enhanced Efflux Activity Facilitates Drug Tolerance in Dormant Bacterial Cells

    PubMed Central

    Pu, Yingying; Zhao, Zhilun; Li, Yingxing; Zou, Jin; Ma, Qi; Zhao, Yanna; Ke, Yuehua; Zhu, Yun; Chen, Huiyi; Baker, Matthew A.B.; Ge, Hao; Sun, Yujie; Xie, Xiaoliang Sunney; Bai, Fan

    2016-01-01

    Summary Natural variations in gene expression provide a mechanism for multiple phenotypes to arise in an isogenic bacterial population. In particular, a sub-group termed persisters show high tolerance to antibiotics. Previously, their formation has been attributed to cell dormancy. Here we demonstrate that bacterial persisters, under β-lactam antibiotic treatment, show less cytoplasmic drug accumulation as a result of enhanced efflux activity. Consistently, a number of multi-drug efflux genes, particularly the central component TolC, show higher expression in persisters. Time-lapse imaging and mutagenesis studies further establish a positive correlation between tolC expression and bacterial persistence. The key role of efflux systems, among multiple biological pathways involved in persister formation, indicates that persisters implement a positive defense against antibiotics prior to a passive defense via dormancy. Finally, efflux inhibitors and antibiotics together effectively attenuate persister formation, suggesting a combination strategy to target drug tolerance. PMID:27105118

  6. Long-term chemiluminescence signal is produced in the course of luminol oxidation catalyzed by enhancer-independent peroxidase purified from Jatropha curcas leaves.

    PubMed

    Duan, Peipei; Cai, Feng; Luo, Yongting; Chen, Yangxi; Zou, Shujuan

    2015-09-01

    Isoenzyme c of horseradish peroxidase (HRP-C) is widely used in enzyme immunoassay combined with chemiluminescence (CL) detection. For this application, HRP-C activity measurement is usually based on luminol oxidation in the presence of hydrogen peroxide (H2O2). However, this catalysis reaction was enhancer dependent. In this study, we demonstrated that Jatropha curcas peroxidase (JcGP1) showed high efficiency in catalyzing luminol oxidation in the presence of H2O2. Compared with HRP-C, the JcGP1-induced reaction was enhancer independent, which made the enzyme-linked immunosorbent assay (ELISA) simpler. In addition, the JcGP1 catalyzed reaction showed a long-term stable CL signal. We optimized the conditions for JcGP1 catalysis and determined the favorable conditions as follows: 50 mM Tris buffer (pH 8.2) containing 10 mM H2 O2, 14 mM luminol and 0.75 M NaCl. The optimum catalysis temperature was 30°C. The detection limit of JcGP1 under optimum condition was 0.2 pM. Long-term stable CL signal combined with enhancer-independent property indicated that JcGP1 might be a valuable candidate peroxidase for clinical diagnosis and enzyme immunoassay with CL detection. PMID:25511847

  7. Conjugation of poly-L-lysine to albumin and horseradish peroxidase: a novel method of enhancing the cellular uptake of proteins.

    PubMed Central

    Shen, W C; Ryser, H J

    1978-01-01

    The carbodiimide-catalyzed conjugation of a 6700 molecular weight fragment of poly-L-lysine to radiolabeled human serum albumin or to horseradish peroxidase enhances the membrane transport of each protein into cultured mouse fibroblasts approximately 11- and 200-fold, respectively. At least 50% of the peroxidase activity remained after conjugation. Trypsinization and carbamylation of the two conjugates demonstrates that the enhancement of their cellular uptake is related to their poly-L-lysine content. Simple addition to the medium of comparable amounts of free poly-L-lysine has no effect on the transport of either native protein. Addition of poly-L-ornithine (molecular weight 200,000) at 3-30 microgram/ml, a condition known to cause enhancement of 125I-labeled human serum albumin uptake by mouse sarcoma cells, has no visible effect on the cellular uptake of native horseradish peroxidase. The intracellular localization of the enzyme-poly-L-lysine conjugate can be demonstrated cytochemically by either light or transmission electron microscopy. A concentration of conjugate that increases the uptake more than 200-fold does not cause any detectable morphological change suggestive of cell toxicity. Furthermore, because poly-L-lysine is an excellent substrate for intracellular proteolytic enzymes, it can be expected to be broken down and reutilized in the cell. Images PMID:273916

  8. Attenuation of experimental colitis in glutathione peroxidase 1 and catalase double knockout mice through enhancing regulatory T cell function.

    PubMed

    Kim, Hyung-Ran; Lee, Anbok; Choi, Eun-Jeong; Kie, Jeong-Hae; Lim, Woosung; Lee, Hyeon Kook; Moon, Byung-In; Seoh, Ju-Young

    2014-01-01

    Reactive oxygen species (ROS) have been implicated in the progression of inflammatory diseases including inflammatory bowel diseases (IBD). Meanwhile, several studies suggested the protective role of ROS in immune-mediated inflammatory diseases, and it was recently reported that dextran sodium sulfate (DSS)-induced colitis was attenuated in mice with an elevated level of ROS due to deficiency of peroxiredoxin II. Regulatory T cells (Tregs) are critical in the prevention of IBD and Treg function was reported to be closely associated with ROS level, but it has been investigated only in lowered levels of ROS so far. In the present study, in order to clarify the relationship between ROS level and Treg function, and their role in the pathogenesis of IBD, we investigated mice with an elevated level of ROS due to deficiency of both glutathione peroxidase (GPx)-1 and catalase (Cat) for the susceptibility of DSS-induced colitis in association with Treg function. The results showed that DSS-induced colitis was attenuated and Tregs were hyperfunctional in GPx1-/- × Cat-/- mice. In vivo administration of N-acetylcysteine (NAC) aggravated DSS-induced colitis and decreased Treg function to the level comparable to WT mice. Attenuated Th17 cell differentiation from naïve CD4+ cells as well as impaired production of IL-6 and IL-17A by splenocytes upon stimulation suggested anti-inflammatory tendency of GPx1-/- × Cat-/- mice. Suppression of Stat3 activation in association with enhancement of indoleamine 2,3-dioxygenase and FoxP3 expression might be involved in the immunosuppressive mechanism of GPx1-/- × Cat-/- mice. Taken together, it is implied that ROS level is critical in the regulation of Treg function, and IBD may be attenuated in appropriately elevated levels of ROS. PMID:24743300

  9. Construction and Characterization of Vitreoscilla Hemoglobin (VHb) with Enhanced Peroxidase Activity for Efficient Degradation of Textile Dye.

    PubMed

    Zhang, Zidong; Li, Wei; Li, Haichao; Zhang, Jing; Zhang, Yuebin; Cao, Yufeng; Ma, Jianzhang; Li, Zhengqiang

    2015-09-01

    Pollution resulting from the discharge of textile dyes into water systems has become a major global concern. Because peroxidases are known for their ability to decolorize and detoxify textile dyes, the peroxidase activity of Vitreoscilla hemoglobin (VHb) has recently been studied. It is found that VHb and variants of this enzyme show great promise for enzymatic decolorization of dyes and may play a role in achieving their successful removal from industrial wastewater. The level of VHb peroxidase activity correlates with two amino acid residues present within the conserved distal pocket, at positions 53 and 54. In this work, sitedirected mutagenesis of these residues was performed and resulted in improved VHb peroxidase activity. The double mutant, Q53H/P54C, shows the highest dye decolorization and removal efficiency, with 70% removal efficiency within 5 min. UV spectral studies of Q53H/P54C reveals a more compact structure and an altered porphyrin environment (λSoret = 413 nm) relative to that of wild-type VHb (λSoret = 406), and differential scanning calorimetry data indicate that the VHb variant protein structure is more stable. In addition, circular dichroism spectroscopic studies indicate that this variant's increased protein structural stability is due to an increase in helical structure, as deduced from the melting temperature, which is higher than 90°C. Therefore, the VHb variant Q53H/P54C shows promise as an excellent peroxidase, with excellent dye decolorization activity and a more stable structure than wild-type VHb under high-temperature conditions. PMID:25907068

  10. Exogenous low-dose hydrogen peroxide enhances drought tolerance of soybean (Glycine max L.) through inducing antioxidant system.

    PubMed

    Guler, Neslihan Saruhan; Pehlivan, Necla

    2016-06-01

    Hydrogen peroxide (H(2)O(2)) functions as a signal molecule in plants under abiotic and biotic stress. In this study, the role of exogenous H(2)O(2) in improving drought tolerance in two soybean cultivars (Glycine max L. Merrill) differing in their tolerance to drought was evaluated. Plants were grown in plastic pots with normal irrigation in a phytotron. Four weeks after radicle emergence, either 1 mM H(2)O(2) or distilled water was sprayed as foliar onto the leaves of each plant, after drought stress was applied. Leaf samples were harvested on the 4(th) and 7(th) days of the drought. Antioxidant-related enzyme activity, such as the superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), hydrogen peroxide (H(2)O(2)) and malondialdehyde (MDA) content was measured during the drought period. Drought stress decreased leaf water potential, relative water content and photosynthetic pigment content but enhanced lipid peroxidation and endogenous H(2)O(2) concentration. By contrast, exogenous low dose H(2)O(2) improved water status, pigment content and lipid peroxidation under drought stress. Endogenous H(2)O(2) concentration was reduced by exogenous H(2)O(2) as compared to drought treatment alone. H(2)O(2) pre-treatment induced all the antioxidant enzyme activities, to a greater extent than the control leaves, during drought. H(2)O(2) pretreatment further enhanced the activities of antioxidant enzymes in the tolerant cultivar compared to the sensitive cultivar. Results suggested that low dose H(2)O(2) pre-treatment alleviated water loss and H(2)O(2) content and increased drought stress tolerance by inducing the antioxidant system. PMID:27165528

  11. Enhanced Accident Tolerant Fuels for LWRS - A Preliminary Systems Analysis

    SciTech Connect

    Gilles Youinou; R. Sonat Sen

    2013-09-01

    The severe accident at Fukushima Daiichi nuclear plants illustrates the need for continuous improvements through developing and implementing technologies that contribute to safe, reliable and cost-effective operation of the nuclear fleet. Development of enhanced accident tolerant fuel contributes to this effort. These fuels, in comparison with the standard zircaloy – UO2 system currently used by the LWR industry, should be designed such that they tolerate loss of active cooling in the core for a longer time period (depending on the LWR system and accident scenario) while maintaining or improving the fuel performance during normal operations, operational transients, and design-basis events. This report presents a preliminary systems analysis related to most of these concepts. The potential impacts of these innovative LWR fuels on the front-end of the fuel cycle, on the reactor operation and on the back-end of the fuel cycle are succinctly described without having the pretension of being exhaustive. Since the design of these various concepts is still a work in progress, this analysis can only be preliminary and could be updated as the designs converge on their respective final version.

  12. Enhancing Methotrexate Tolerance with Folate Tagged Liposomes in Arthritic Mice.

    PubMed

    Nogueira, Eugénia; Lager, Franck; Le Roux, Delphine; Nogueira, Patrícia; Freitas, Jaime; Charvet, Celine; Renault, Gilles; Loureiro, Ana; Almeida, Catarina R; Ohradanova-Repic, Anna; Machacek, Christian; Bernardes, Gonçalo J L; Moreira, Alexandra; Stockinger, Hannes; Burnet, Michael; Carmo, Alexandre M; Gomes, Andreia C; Preto, Ana; Bismuth, Georges; Cavaco-Paulo, Artur

    2015-12-01

    Methotrexate is the first line of treatment of rheumatoid arthritis. Since many patients become unresponsive to methotrexate treatment, only very expensive biological therapies are effective and increased methotrexate tolerance strategies need to be identified. Here we propose the encapsulation of methotrexate in a new liposomal formulation using a hydrophobic fragment of surfactant protein conjugated to a linker and folate to enhance their tolerance and efficacy. In this study we aim to evaluate the efficiency of this system to treat rheumatoid arthritis, by targeting folate receptor β present at the surface of activated macrophages, key effector cells in this pathology. The specificity of our liposomal formulation to target folate receptor β was investigated both in vitro as in vivo using a mouse model of arthritis (collagen-induced arthritis in DBA/1J mice strain). In both systems, the liposomal constructs were shown to be highly specific and efficient in targeting folate receptor β. These liposomal formulations also significantly increase the clinical benefit of the encapsulated methotrexate in vivo in arthritic mice, together with reduced expression of CD39 and CD73 ectonucleotidases by joint-infiltrating macrophages. Thus, our formulation might be a promising cost effective way to treat rheumatoid arthritis and delay or reduce methotrexate intolerance. PMID:26510317

  13. Buffered coscheduling for parallel programming and enhanced fault tolerance

    DOEpatents

    Petrini, Fabrizio; Feng, Wu-chun

    2006-01-31

    A computer implemented method schedules processor jobs on a network of parallel machine processors or distributed system processors. Control information communications generated by each process performed by each processor during a defined time interval is accumulated in buffers, where adjacent time intervals are separated by strobe intervals for a global exchange of control information. A global exchange of the control information communications at the end of each defined time interval is performed during an intervening strobe interval so that each processor is informed by all of the other processors of the number of incoming jobs to be received by each processor in a subsequent time interval. The buffered coscheduling method of this invention also enhances the fault tolerance of a network of parallel machine processors or distributed system processors

  14. A bHLH gene from Tamarix hispida improves abiotic stress tolerance by enhancing osmotic potential and decreasing reactive oxygen species accumulation.

    PubMed

    Ji, Xiaoyu; Nie, Xianguang; Liu, Yujia; Zheng, Lei; Zhao, Huimin; Zhang, Bing; Huo, Lin; Wang, Yucheng

    2016-02-01

    Basic helix-loop-helix (bHLH) leucine-zipper transcription factors play important roles in abiotic stress responses. However, their specific roles in abiotic stress tolerance are not fully known. Here, we functionally characterized a bHLH gene, ThbHLH1, from Tamarix hispida in abiotic stress tolerance. ThbHLH1 specifically binds to G-box motif with the sequence of 'CACGTG'. Transiently transfected T. hispida plantlets with transiently overexpressed ThbHLH1 and RNAi-silenced ThbHLH1 were generated for gain- and loss-of-function analysis. Transgenic Arabidopsis thaliana lines overexpressing ThbHLH1 were generated to confirm the gain- and loss-of-function analysis. Overexpression of ThbHLH1 significantly elevates glycine betaine and proline levels, increases Ca(2+) concentration and enhances peroxidase (POD) and superoxide dismutase (SOD) activities to decrease reactive oxygen species (ROS) accumulation. Additionally, ThbHLH1 regulates the expression of the genes including P5CS, BADH, CaM, POD and SOD, to activate the above physiological changes, and also induces the expression of stress tolerance-related genes LEAs and HSPs. These data suggest that ThbHLH1 induces the expression of stress tolerance-related genes to improve abiotic stress tolerance by increasing osmotic potential, improving ROS scavenging capability and enhancing second messenger in stress signaling cascades. PMID:26786541

  15. Enhanced salt stress tolerance in transgenic potato plants expressing IbMYB1, a sweet potato transcription factor.

    PubMed

    Cheng, Yu-Jie; Kim, Myoung-Duck; Deng, Xi-Ping; Kwak, Sang-Soo; Chen, Wei

    2013-12-01

    IbMYB1, a transcription factor (TF) for R2R3-type MYB TFs, is a key regulator of anthocyanin biosynthesis during storage of sweet potatoes. Anthocyanins provide important antioxidants of nutritional value to humans, and also protect plants from oxidative stress. This study aimed to increase transgenic potatoes' (Solanum tuberosum cv. LongShu No.3) tolerance to environmental stress and enhance their nutritional value. Transgenic potato plants expressing IbMYB1 genes under the control of an oxidative stress-inducible peroxidase (SWPA2) promoter (referred to as SM plants) were successfully generated through Agrobacterium-mediated transformation. Two representative transgenic SM5 and SM12 lines were evaluated for enhanced tolerance to salinity, UV-B rays, and drought conditions. Following treatment of 100 mM NaCl, seedlings of SM5 and SM12 lines showed less root damage and more shoot growth than control lines expressing only an empty vector. Transgenic potato plants in pots treated with 400 mM NaCl showed high amounts of secondary metabolites, including phenols, anthocyanins, and flavonoids, compared with control plants. After treatment of 400 mM NaCl, transgenic potato plants also showed high DDPH radical scavenging activity and high PS II photochemical efficiency compared with the control line. Furthermore, following treatment of NaCl, UV-B, and drought stress, the expression levels of IbMYB1 and several structural genes in the flavonoid biosynthesis such as CHS, DFR, and ANS in transgenic plants were found to be correlated with plant phenotype. The results suggest that enhanced IbMYB1 expression affects secondary metabolism, which leads to improved tolerance ability in transgenic potatoes. PMID:24378636

  16. Enhancing sensitivity and selectivity in a label-free colorimetric sensor for detection of iron(II) ions with luminescent molybdenum disulfide nanosheet-based peroxidase mimetics.

    PubMed

    Wang, Yong; Hu, Jie; Zhuang, Qianfen; Ni, Yongnian

    2016-06-15

    In the present study, we demonstrated that the luminescent molybdenum disulfide (MoS2) nanosheets, which were prepared hydrothermally by using sodium molybdate and thiourea as precursors, possessed peroxidase-like activity, and could catalyze the oxidation of peroxidase substrate o-phenylenediamine (OPD) in the presence of hydrogen peroxide (H2O2) to produce a yellow color reaction. Further addition of Fe(2+) into the nanosheets led to peroxidase mimetics with greatly enhanced catalytic activity. The observation was exploited to develop a label-free colorimetric nanozyme sensor for detection of Fe(2+). The fabricated MoS2/OPD/H2O2 sensor showed a wide linear range of 0.01-0.8 µM with a detection limit of 7 nM. Moreover, it was found that the MoS2/OPD/H2O2 sensor displayed enhanced sensitivity and selectivity toward Fe(2+) compared with the OPD/H2O2 sensor, suggesting that the MoS2 nanosheets could improve the performance of the Fe(2+) sensor. An advanced chemometrics algorithm, multivariate curve resolution by alternating least squares (MCR-ALS), was further applied to interpret the origin of enhancing sensitivity and selectivity in the Fe(2+) sensor with the MoS2 nanosheets. The time-dependent UV-vis spectral data of the studied systems were collected, and submitted to the MCR-ALS. The results showed that the increased sensitivity and selectivity of the MoS2/OPD/H2O2 sensor for Fe(2+) detection likely arose from its large reaction rate constant. Finally, the proposed MoS2/OPD/H2O2 sensor was successfully applied for detection of Fe(2+) in water samples. PMID:26807525

  17. DNA-enhanced peroxidase-like activity of layered double hydroxide nanosheets and applications in H2O2 and glucose sensing

    NASA Astrophysics Data System (ADS)

    Chen, Lijian; Sun, Kaifang; Li, Peipei; Fan, Xianzhong; Sun, Jianchao; Ai, Shiyun

    2013-10-01

    LDH nanosheets were obtained via continuous impaction and exfoliation by herring sperm DNA molecules using a constant vibration method. DNA-LDH nanohybrids were composed by electrostatic forces and they exhibited DNA-enhanced peroxidase-like activity. The morphology and structure of DNA-LDH nanohybrids were analyzed by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and atomic force microscopy (AFM) characterization. On the basis of the high catalytic activity of DNA/CuAl-LDH nanosheets, a rapid, sensitive, and convenient approach was developed for colorimetric detection of H2O2 and blood glucose. This method can be potentially applied in medical diagnostics and biotechnology fields.LDH nanosheets were obtained via continuous impaction and exfoliation by herring sperm DNA molecules using a constant vibration method. DNA-LDH nanohybrids were composed by electrostatic forces and they exhibited DNA-enhanced peroxidase-like activity. The morphology and structure of DNA-LDH nanohybrids were analyzed by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and atomic force microscopy (AFM) characterization. On the basis of the high catalytic activity of DNA/CuAl-LDH nanosheets, a rapid, sensitive, and convenient approach was developed for colorimetric detection of H2O2 and blood glucose. This method can be potentially applied in medical diagnostics and biotechnology fields. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03031h

  18. Enhancement of the Chaperone Activity of Alkyl Hydroperoxide Reductase C from Pseudomonas aeruginosa PAO1 Resulting from a Point-Specific Mutation Confers Heat Tolerance in Escherichia coli.

    PubMed

    Lee, Jae Taek; Lee, Seung Sik; Mondal, Suvendu; Tripathi, Bhumi Nath; Kim, Siu; Lee, Keun Woo; Hong, Sung Hyun; Bai, Hyoung-Woo; Cho, Jae-Young; Chung, Byung Yeoup

    2016-08-31

    Alkyl hydroperoxide reductase subunit C from Pseudomonas aeruginosa PAO1 (PaAhpC) is a member of the 2-Cys peroxiredoxin family. Here, we examined the peroxidase and molecular chaperone functions of PaAhpC using a site-directed mutagenesis approach by substitution of Ser and Thr residues with Cys at positions 78 and 105 located between two catalytic cysteines. Substitution of Ser with Cys at position 78 enhanced the chaperone activity of the mutant (S78C-PaAhpC) by approximately 9-fold compared with that of the wild-type protein (WT-PaAhpC). This increased activity may have been associated with the proportionate increase in the high-molecular-weight (HMW) fraction and enhanced hydrophobicity of S78C-PaAhpC. Homology modeling revealed that mutation of Ser(78) to Cys(78) resulted in a more compact decameric structure than that observed in WT-PaAhpC and decreased the atomic distance between the two neighboring sulfur atoms of Cys(78) in the dimer-dimer interface of S78C-PaAhpC, which could be responsible for the enhanced hydrophobic interaction at the dimer-dimer interface. Furthermore, complementation assays showed that S78C-PaAhpC exhibited greatly improved the heat tolerance, resulting in enhanced survival under thermal stress. Thus, addition of Cys at position 78 in PaAhpC modulated the functional shifting of this protein from a peroxidase to a chaperone. PMID:27457208

  19. Enhancement of the Chaperone Activity of Alkyl Hydroperoxide Reductase C from Pseudomonas aeruginosa PAO1 Resulting from a Point-Specific Mutation Confers Heat Tolerance in Escherichia coli

    PubMed Central

    Lee, Jae Taek; Lee, Seung Sik; Mondal, Suvendu; Tripathi, Bhumi Nath; Kim, Siu; Lee, Keun Woo; Hong, Sung Hyun; Bai, Hyoung-Woo; Cho, Jae-Young; Chung, Byung Yeoup

    2016-01-01

    Alkyl hydroperoxide reductase subunit C from Pseudomonas aeruginosa PAO1 (PaAhpC) is a member of the 2-Cys peroxiredoxin family. Here, we examined the peroxidase and molecular chaperone functions of PaAhpC using a site-directed mutagenesis approach by substitution of Ser and Thr residues with Cys at positions 78 and 105 located between two catalytic cysteines. Substitution of Ser with Cys at position 78 enhanced the chaperone activity of the mutant (S78C-PaAhpC) by approximately 9-fold compared with that of the wild-type protein (WT-PaAhpC). This increased activity may have been associated with the proportionate increase in the high-molecular-weight (HMW) fraction and enhanced hydrophobicity of S78C-PaAhpC. Homology modeling revealed that mutation of Ser78 to Cys78 resulted in a more compact decameric structure than that observed in WT-PaAhpC and decreased the atomic distance between the two neighboring sulfur atoms of Cys78 in the dimer-dimer interface of S78C-PaAhpC, which could be responsible for the enhanced hydrophobic interaction at the dimer-dimer interface. Furthermore, complementation assays showed that S78C-PaAhpC exhibited greatly improved the heat tolerance, resulting in enhanced survival under thermal stress. Thus, addition of Cys at position 78 in PaAhpC modulated the functional shifting of this protein from a peroxidase to a chaperone. PMID:27457208

  20. CASE STUDY FOR ENHANCED ACCIDENT TOLERANCE DESIGN CHANGES

    SciTech Connect

    Prescott, Steven; Smith, Curtis; Koonce, Tony

    2014-09-01

    The ability to better characterize and quantify safety margin is important to improved decision making about Light Water Reactor (LWR) design, operation, and plant life extension. A systematic approach to characterization of safety margins and the subsequent margin management options represents a vital input to the licensee and regulatory analysis and decision making that will be involved. In addition, as research and development in the LWR Sustainability (LWRS) Program and other collaborative efforts yield new data, sensors, and improved scientific understanding of physical processes that govern the aging and degradation of plant SSCs needs and opportunities to better optimize plant safety and performance will become known. To support decision making related to economics, readability, and safety, the Risk Informed Safety Margin Characterization (RISMC) Pathway provides methods and tools that enable mitigation options known as risk informed margins management (RIMM) strategies. The methods and tools provided by RISMC are essential to a comprehensive and integrated RIMM approach that supports effective preservation of margin for both active and passive SSCs. In this report, we discuss the methods and technologies behind RIMM for an application focused on enhanced accident tolerance design changes for a representative nuclear power plant. We look at a variety of potential plant modifications and evaluate, using the RISMC approach, the implications to safety margin for the various strategies.

  1. [Enhancement of Coprinus cinereus peroxidase in Pichia pastoris by co-expression chaperone PDI and Ero1].

    PubMed

    Chen, Fei; Hu, Meirong; Jiang, Xianzhang; Tao, Yong; Huang, Jianzhong

    2015-12-01

    The 1,095 bp gene encoding peroxidase from Coprinus cinereus was synthesized and integrated into the genome of Pichia pastoris with a highly inducible alcohol oxidase. The recombinant CiP (rCiP) fused with the a-mating factor per-pro leader sequence derived from Saccharomyces cerevisiae was secreted into the culture medium and identified as the target protein by mass spectrometry, confirming that a C. cinereus peroxidase (CiP) was successfully expressed in P. pastoris. The endoplasmic reticulum oxidoreductase 1 (Ero1) and protein disulfide isomerase (PDI) were co-expressed with rCiP separately and simultaneously. Compared with the wild type, overexpression of PDI and Erol-PDI increaseed Cip activity in 2.43 and 2.6 fold and their activity reached 316 U/mL and 340 U/mL respectively. The strains co-expressed with Erol-PDI was used to high density fermentation, and their activity reached 3,379 U/mL, which was higher than previously reported of 1,200 U/mL. PMID:27093831

  2. Quantitative assay of PCR-amplified hepatitis B virus DNA using a peroxidase-labelled DNA probe and enhanced chemiluminescence.

    PubMed Central

    Erhardt, A; Schaefer, S; Athanassiou, N; Kann, M; Gerlich, W H

    1996-01-01

    We have developed a sensitive and quantitative assay for hepatitis B virus (HBV) DNA in serum or plasma in which PCR and then microtiter hybridization analysis are used. Assay of HBV DNA in serum or plasma is important for demonstrating viral replication, indicating and monitoring antiviral therapy, determining the infectivities of virus carriers, and ensuring the safety of blood products. Under optimum conditions PCR can amplify one HBV DNA molecule to 10(8) copies, but detection of this amount of DNA still requires hybridization with labelled probes or a nested PCR. We labelled one strand of the PCR product with a biotinylated primer. The double-stranded amplicon was incubated in streptavidin-coated microplate wells. The nonlabelled strand was removed after denaturation of the double-stranded DNA with alkali, and the bound strand was hybridized with a peroxidase-coupled single-stranded probe. The amount of bound peroxidase was measured in a luminometer. Four picograms of amplicon was detectable in this system, whereas conventional ethidium bromide staining requires a 1,000 times higher amplicon concentration. The performance of the new assay was compared with those of nested PCR and a PCR system that uses a digoxigenin label, hybridization to a solid-phase adsorbed probe, and colorimetric detection. The chemiluminescence assay was found to be almost as sensitive as nested PCR and approximately five times more sensitive than the colorimetric test. PMID:8818875

  3. Yeast thioredoxin peroxidase expression enhances the resistance of Escherichia coli to oxidative stress induced by singlet oxygen.

    PubMed

    Kim, Sun Yee; Kim, Eun Ju; Park, Jeen-Woo

    2002-01-01

    Singlet oxygen ((1)O(2)) is a highly reactive form of molecular oxygen that may harm living systems by oxidizing critical cellular macromolecules. A soluble protein from Saccharomyces cerevisiae specifically provides protection against a thiol-containing metal-catalyzed oxidation system (thiol/Fe(3+)/O(2)) but not against an oxidation system without thiol. This 25 kDa protein acts as a peroxidase but requires the NADPH-dependent thioredoxin system or a thiol-containing intermediate, and was named thioredoxin peroxidase (TPx). The role of TPx in the cellular defense against oxidative stress induced by singlet oxygen was investigated in Escherichia coli containing an expression vector with a yeast genomic DNA fragment that encodes TPx and mutant in which the catalytically essential amino acid cysteine (Cys-47) has been replaced with alanine by a site-directed mutagenesis. Upon exposure to methylene blue and visible light, which generates singlet oxygen, there was a distinct difference between the two strains in regard to growth kinetics, viability, the accumulation of oxidized proteins and lipids, and modulation of activities of superoxide dismutase and catalase. The results suggest that TPx may play an important protective role in a singlet oxygen-mediated cellular damage. PMID:12189053

  4. Impedimetric aptasensor for nuclear factor kappa B with peroxidase-like mimic coupled DNA nanoladders as enhancer.

    PubMed

    Peng, Kanfu; Zhao, Hongwen; Xie, Pan; Hu, Shuang; Yuan, Yali; Yuan, Ruo; Wu, Xiongfei

    2016-07-15

    In this work, we developed a sensitive and universal aptasensor for nuclear factor kappa B (NF-κB) detection based on peroxidase-like mimic coupled DNA nanoladders for signal amplification. The dsDNA formed by capture DNA S1 and NF-κB binding aptamer (NBA) was firstly assembled on electrode surface. The presence of target NF-κB then led to the leave of NBA from electrode surface and thus provided the binding sites for immobilizing initiator to trigger in situ formation of DNA nanoladders on electrode surface. Since the peroxidase-like mimic manganese (III) meso-tetrakis (4-Nmethylpyridyl)-porphyrin (MnTMPyP) interacts with DNA nanoladders via groove binding, the insoluble benzo-4-chlorohexadienone (4-CD) precipitation derived from the oxidation of 4-chloro-1-naphthol (4-CN) could be formed on electrode surface in the presence of H2O2, resulting in a significantly amplified EIS signal output for quantitative target analysis. As a result, the developed aptasensor showed a low detection limit of 7pM and a wide linear range of 0.01-20nM. Featured with high sensitivity and label-free capability, the proposed sensing scheme can thus offer new opportunities for achieving sensitive, selective and stable detection of different types of target proteins. PMID:26913501

  5. Genetic Enhancement of Cold Tolerance in Sorghum: Mapping of QTL's for early season cold tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sorghum is known for its drought tolerance and overall adaptation to high temperature. However, it generally lacks cold tolerance and is vulnerable to cooler temperature specifically during stand establishment in early season planting from April to May in most areas of the US sorghum belt. Stand e...

  6. Bulk Nanostructured FCC Steels With Enhanced Radiation Tolerance

    SciTech Connect

    Zhang, Xinghang; Hartwig, K. Ted; Allen, Todd; Yang, Yong

    2012-10-27

    The objective of this project is to increase radiation tolerance in austenitic steels through optimization of grain size and grain boundary (GB) characteristics. The focus will be on nanocrystalline austenitic Fe-Cr-Ni alloys with an fcc crystal structure. The long-term goal is to design and develop bulk nanostructured austenitic steels with enhanced void swelling resistance and substantial ductility, and to enhance their creep resistance at elevated temperatures via GB engineering. The combination of grain refinement and grain boundary engineering approaches allows us to tailor the material strength, ductility, and resistance to swelling by 1) changing the sink strength for point defects, 2) by increasing the nucleation barriers for bubble formation at GBs, and 3) by changing the precipitate distributions at boundaries. Compared to ferritic/martensitic steels, austenitic stainless steels (SS) possess good creep and fatigue resistance at elevated temperatures, and better toughness at low temperature. However, a major disadvantage of austenitic SS is that they are vulnerable to significant void swelling in nuclear reactors, especially at the temperatures and doses anticipated in the Advanced Burner Reactor. The lack of resistance to void swelling in austenitic alloys led to the switch to ferritic/martensitic steels as the preferred material for the fast reactor cladding application. Recently a type of austenitic stainless steel, HT-UPS, was developed at ORNL, and is expected to show enhanced void swelling resistance through the trapping of point defects at nanometersized carbides. Reducing the grain size and increasing the fraction of low energy grain boundaries should reduce the available radiation-produced point defects (due to the increased sink area of the grain boundaries), should make bubble nucleation at the boundaries less likely (by reducing the fraction of high-energy boundaries), and improve the strength and ductility under radiation by producing a higher

  7. High power bipolar battery/cells with enhanced overcharge tolerance

    DOEpatents

    Kaun, T.D.

    1998-04-07

    A cell or battery of cells having improved overcharge tolerance and increased power capability, and methods for the construction of such cells or batteries, via electrolyte modification, are described. 5 figs.

  8. The RING Finger Ubiquitin E3 Ligase OsHTAS Enhances Heat Tolerance by Promoting H2O2-Induced Stomatal Closure in Rice.

    PubMed

    Liu, Jianping; Zhang, Cuicui; Wei, Chuchu; Liu, Xin; Wang, Mugui; Yu, Feifei; Xie, Qi; Tu, Jumin

    2016-01-01

    Heat stress often results in the generation of reactive oxygen species, such as hydrogen peroxide, which plays a vital role as a secondary messenger in the process of abscisic acid (ABA)-mediated stomatal closure. Here, we characterized the rice (Oryza sativa) HEAT TOLERANCE AT SEEDLING STAGE (OsHTAS) gene, which plays a positive role in heat tolerance at the seedling stage. OsHTAS encodes a ubiquitin ligase localized to the nucleus and cytoplasm. OsHTAS expression was detected in all tissues surveyed and peaked in leaf blade, in which the expression was concentrated in mesophyll cells. OsHTAS was responsive to multiple stresses and was strongly induced by exogenous ABA. In yeast two-hybrid assays, OsHTAS interacted with components of the ubiquitin/26S proteasome system and an isoform of rice ascorbate peroxidase. OsHTAS modulated hydrogen peroxide accumulation in shoots, altered the stomatal aperture status of rice leaves, and promoted ABA biosynthesis. The results suggested that the RING finger ubiquitin E3 ligase OsHTAS functions in leaf blade to enhance heat tolerance through modulation of hydrogen peroxide-induced stomatal closure and is involved in both ABA-dependent and DROUGHT AND SALT TOLERANCE-mediated pathways. PMID:26564152

  9. Enhanced Glutathione Peroxidase Activity of Water-Soluble and Polyethylene Glycol-Supported Selenides, Related Spirodioxyselenuranes, and Pincer Selenuranes.

    PubMed

    McNeil, Nicole M R; Press, David J; Mayder, Don M; Garnica, Pablo; Doyle, Lisa M; Back, Thomas G

    2016-09-01

    Diaryl selenides containing o-hydroxymethylene substituents function as peroxide-destroying mimetics of the antioxidant selenoenzyme glutathione peroxidase (GPx), via oxidation to the corresponding spirodioxyselenuranes with hydrogen peroxide and subsequent reduction back to the original selenides with glutathione. Parent selenides with 3-hydroxypropyl or 2,3-dihydroxypropyl groups produced the novel compounds 10 and 11, respectively, with greatly improved aqueous solubility and catalytic activity. The phenolic derivative 28 displayed similarly ameliorated properties and also modest radical-inhibiting antioxidant activity, as evidenced by an assay based on phenolic hydrogen atom transfer to the stable free radical DPPH. In contrast, several selenides that afford pincer selenuranes (e.g., 20 and 21) instead of spiroselenuranes upon oxidation showed inferior catalytic activity. Several selenide analogues were attached to polyethylene glycol (PEG) oligomers, as PEG substituents can improve water solubility and bioavailability, while retarding clearance. Again, the PEG derivatives afforded remarkable activity when oxidation generated spirodioxyselenuranes and diminished activity when pincer compounds were produced. Several such compounds proved to be ca. 10- to 100-fold catalytically superior to the diaryl selenides and their spirodioxyselenurane counterparts investigated previously. Finally, an NMR-based assay employing glutathione in D2O was designed to accommodate the faster reacting water-soluble mimetics and to more closely duplicate in vivo conditions. PMID:27525346

  10. Crude soybean hull peroxidase treatment of phenol in synthetic and real wastewater: enzyme economy enhanced by Triton X-100.

    PubMed

    Steevensz, Aaron; Madur, Sneha; Feng, Wei; Taylor, Keith E; Bewtra, Jatinder K; Biswas, Nihar

    2014-02-01

    Soybean peroxidase (SBP)-catalyzed removal of phenol from wastewater has been demonstrated as a feasible wastewater treatment strategy and a non-ionic surfactant, Triton X-100, has the potential for increasing the enzyme economy of the process. Systematic studies on the enzyme-surfactant system have been lacking as well as demonstration of its applicability to industrial wastewater. This paper addresses those two gaps, the latter based on real wastewater from alkyd resin manufacture. The minimum effective Triton X-100 concentrations for crude SBP-catalyzed phenol conversion (≥95%) over 1-10 mM showed a linear trend. To illustrate translation of such lab results to real-world samples, this data were used to optimize crude SBP needed for phenol conversion over that concentration range. Triton X-100 increases enzyme economy by 10- to 13-fold. This treatment protocol was directly applied to tote-scale (700-1000 L) treatment of alkyd resin wastewater, with phenol ranging from 7 to 28 mM and total organic carbon content of >40 g/L, using a crude SBP extract derived from dry soybean hulls by simple aqueous elution. This extract can be used to remove phenol from a complex industrial wastewater and the process is markedly more efficient in the presence of Triton X-100. The water is thus rendered amenable to conventional biological treatment whilst the hulls could still be used in feed, thus adding further value to the crop. PMID:24411447

  11. Enhancement of aluminum tolerance in wheat by addition of chromosomes from the wild relative Leymus racemosus

    PubMed Central

    Mohammed, Yasir Serag Alnor; Eltayeb, Amin Elsadig; Tsujimoto, Hisashi

    2013-01-01

    Aluminum (Al) toxicity is the key factor limiting wheat production in acid soils. Soil liming has been used widely to increase the soil pH, but due to its high cost, breeding tolerant cultivars is more cost-effective mean to mitigate the problem. Tolerant cultivars could be developed by traditional breeding, genetic transformation or introgression of genes from wild relatives. We used 30 wheat alien chromosome addition lines to identify new genetic resources to improve wheat tolerance to Al and to identify the chromosomes harboring the tolerance genes. We evaluated these lines and their wheat background Chinese Spring for Al tolerance in hydroponic culture at various Al concentrations. We also investigated Al uptake, oxidative stress and cell membrane integrity. The L. racemosus chromosomes A and E significantly enhanced the Al tolerance of the wheat in term of relative root growth. At the highest Al concentration tested (200 μM), line E had the greatest tolerance. The introgressed chromosomes did not affect Al uptake of the tolerant lines. We attribute the improved tolerance conferred by chromosome E to improved cell membrane integrity. Chromosome engineering with these two lines could produce Al-tolerant wheat cultivars. PMID:24399913

  12. Enhancement of aluminum tolerance in wheat by addition of chromosomes from the wild relative Leymus racemosus.

    PubMed

    Mohammed, Yasir Serag Alnor; Eltayeb, Amin Elsadig; Tsujimoto, Hisashi

    2013-12-01

    Aluminum (Al) toxicity is the key factor limiting wheat production in acid soils. Soil liming has been used widely to increase the soil pH, but due to its high cost, breeding tolerant cultivars is more cost-effective mean to mitigate the problem. Tolerant cultivars could be developed by traditional breeding, genetic transformation or introgression of genes from wild relatives. We used 30 wheat alien chromosome addition lines to identify new genetic resources to improve wheat tolerance to Al and to identify the chromosomes harboring the tolerance genes. We evaluated these lines and their wheat background Chinese Spring for Al tolerance in hydroponic culture at various Al concentrations. We also investigated Al uptake, oxidative stress and cell membrane integrity. The L. racemosus chromosomes A and E significantly enhanced the Al tolerance of the wheat in term of relative root growth. At the highest Al concentration tested (200 μM), line E had the greatest tolerance. The introgressed chromosomes did not affect Al uptake of the tolerant lines. We attribute the improved tolerance conferred by chromosome E to improved cell membrane integrity. Chromosome engineering with these two lines could produce Al-tolerant wheat cultivars. PMID:24399913

  13. Mechanistic study of CuZn-SOD from Ipomoea carnea mutated at dimer interface: enhancement of peroxidase activity upon monomerization.

    PubMed

    Mishra, Panchanand; Dixit, Anshuman; Ray, Mamata; Sabat, Surendra Chandra

    2014-02-01

    The enzymatically active monomeric form of CuZn-superoxide dismutase has always been of interest to decipher the structure-function relationship in this class of enzymes. In the present study, spectroscopic and enzymatic characteristics of the dimeric and monomeric forms of recombinant Ipomoea carnea CuZn-superoxide dismutase were made to decipher their stability and altered catalytic properties. The monomeric form of protein was produced through site directed mutagenesis by replacing a conserved hydrophobic leucine with a polar lysine residue at the dimer-interface. Spectral characteristics of both the forms (monomer and dimer) showed the presence of novel electronic transitions. Superoxide scavenging activity of the mutated form was reduced to nearly half of the activity found in the native enzyme. Concomitantly, compared to native form the mutated enzyme showed an increase in peroxidase activity. High temperature dependent circular dichroism spectral analysis, differential scanning calorimetric profile, and the measurement of temperature dependent superoxide scavenging activity indicated an increased susceptibility of the mutated form to higher temperature as compared to the native form. The inhibitor studies like hydrogen peroxide, diethyldithiocarbamate and phenylglyoxal also indicate higher susceptibility, which might be due to, altered arrangement of active site residues as a consequence of the mutation. Molecular modeling and MD simulation studies further indicated that this specific mutation induces loss of hydrophobic interaction at dimer interface, resulting in the observed instability of the dimeric form. Increased peroxidative activity of the enzyme, upon monomerization may have physiological implication essentially in presence of high concentration of H2O2, as in case of plant cells specifically under stress conditions. PMID:24513093

  14. Processing and circuit design enhance a data converter's radiation tolerance

    SciTech Connect

    Heuner, R.; Zazzu, V.; Pennisi, L.

    1988-12-01

    Rad-hard CMOS/SOS processing has been applied to a novel comparator-inverter circuit design to develop 6 and 8-bit parallel (flash) ADC (analog-to-digital converter) circuits featuring high-speed operation, low power consumption, and total-dose radiation tolerances up to 1 Mrad(Si).

  15. Heterologous Expression of Peroxidases

    NASA Astrophysics Data System (ADS)

    de Weert, Sandra; Lokman, B. Christien

    The industrial importance of peroxidases has led to much research in the past two decades on the development of a cost effective and efficient production process for peroxidases. Unfortunately, even today, no clear answers can be given to questions such as (1) should the peroxidase be expressed in bacteria, yeast, or fungi? (2) which is the optimal production strain (e.g., protease deficient, heme overproducing)? (3) which expression vector should be chosen? and (4) what purification method should be used? Strategies that have proven successful for one peroxidase can fail for another one; for each individual peroxidase, a new strategy has to be developed. This chapter gives an overview of the heterologous production of heme containing peroxidases in various systems. It focuses on the heterologous production of fungal peroxidases as they have been subject of considerable research for their industrial and environmental applications. An earlier study has also been performed by Conesa et al. [1] and is extended with recent proceedings.

  16. Selective chemical binding enhances cesium tolerance in plants through inhibition of cesium uptake

    NASA Astrophysics Data System (ADS)

    Adams, Eri; Chaban, Vitaly; Khandelia, Himanshu; Shin, Ryoung

    2015-03-01

    High concentrations of cesium (Cs+) inhibit plant growth but the detailed mechanisms of Cs+ uptake, transport and response in plants are not well known. In order to identify small molecules with a capacity to enhance plant tolerance to Cs+, chemical library screening was performed using Arabidopsis. Of 10,000 chemicals tested, five compounds were confirmed as Cs+ tolerance enhancers. Further investigation and quantum mechanical modelling revealed that one of these compounds reduced Cs+ concentrations in plants and that the imidazole moiety of this compound bound specifically to Cs+. Analysis of the analogous compounds indicated that the structure of the identified compound is important for the effect to be conferred. Taken together, Cs+ tolerance enhancer isolated here renders plants tolerant to Cs+ by inhibiting Cs+ entry into roots via specific binding to the ion thus, for instance, providing a basis for phytostabilisation of radiocesium-contaminated farmland.

  17. Development of LWR Fuels with Enhanced Accident Tolerance

    SciTech Connect

    Lahoda, Edward J.; Boylan, Frank A.

    2015-10-30

    Significant progress was made on the technical, licensing, and business aspects of the Westinghouse Electric Company’s Enhanced Accident Tolerant Fuel (ATF) by the Westinghouse ATF team. The fuel pellet options included waterproofed U15N and U3Si2 and the cladding options SiC composites and zirconium alloys with surface treatments. Technology was developed that resulted in U3Si2 pellets with densities of >94% being achieved at the Idaho National Laboratory (INL). The use of U3Si2 will represent a 15% increase in U235 loadings over those in UO₂ fuel pellets. This technology was then applied to manufacture pellets for 6 test rodlets which were inserted in the Advanced Test Reactor (ATR) in early 2015 in zirconium alloy cladding. The first of these rodlets are expected to be removed in about 2017. Key characteristics to be determined include verification of the centerline temperature calculations, thermal conductivity, fission gas release, swelling and degree of amorphization. Waterproofed UN pellets have achieved >94% density for a 32% U3Si2/68% UN composite pellet at Texas A&M University. This represents a U235 increase of about 31% over current UO2 pellets. Pellets and powders of UO2, UN, and U3Si2the were tested by Westinghouse and Los Alamos National Laboratory (LANL) using differential scanning calorimetry to determine what their steam and 20% oxygen corrosion temperatures were as compared to UO2. Cold spray application of either the amorphous steel or the Ti2AlC was successful in forming an adherent ~20 micron coating that remained after testing at 420°C in a steam autoclave. Tests at 1200°C in 100% steam on coatings for Zr alloy have not been successful, possibly due to the low density of the coatings which allowed steam transport to the base zirconium metal. Significant modeling and testing

  18. On the enhancement of impact damage tolerance of composite laminates

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.; Lance, D. G.

    1993-01-01

    This paper examines the use of a thin layer of Ultra High Molecular Weight Polyethylene (UHMWPE) on the outer surface of carbon/epoxy composite materials as a method of improving impact resistance and damage tolerance through hybridization. Flat 16-ply laminates as well as honeycomb sandwich structures with eight-ply facesheets were tested in this study. Instrumented drop-weight impact testing was used to inflict damage upon the specimens. Evaluation of damage resistance included instrumented impact data, visual examination, C-scanning and compression after impact (CAI) testing. The results show that only one lamina of UHMWPE did not improve the damage tolerance (strength retention) of the 16-ply flat laminate specimens or the honeycomb sandwich beams, however, a modest gain in impact resistance (detectable damage) was found for the honeycomb sandwich specimens that contained an outer layer of UHMWPE.

  19. Cyanobacteria-mediated phenylpropanoids and phytohormones in rice (Oryza sativa) enhance plant growth and stress tolerance.

    PubMed

    Singh, Dhananjaya P; Prabha, Ratna; Yandigeri, Mahesh S; Arora, Dilip K

    2011-11-01

    Phenylpropanoids, flavonoids and plant growth regulators in rice (Oryza sativa) variety (UPR 1823) inoculated with different cyanobacterial strains namely Anabaena oryzae, Anabaena doliolum, Phormidium fragile, Calothrix geitonos, Hapalosiphon intricatus, Aulosira fertilissima, Tolypothrix tenuis, Oscillatoria acuta and Plectonema boryanum were quantified using HPLC in pot conditions after 15 and 30 days. Qualitative analysis of the induced compounds using reverse phase HPLC and further confirmation with LC-MS/MS showed consistent accumulation of phenolic acids (gallic, gentisic, caffeic, chlorogenic and ferulic acids), flavonoids (rutin and quercetin) and phytohormones (indole acetic acid and indole butyric acid) in rice leaves. Plant growth promotion (shoot, root length and biomass) was positively correlated with total protein and chlorophyll content of leaves. Enzyme activity of peroxidase and phenylalanine ammonia lyase and total phenolic content was fairly high in rice leaves inoculated with O. acuta and P. boryanum after 30 days. Differential systemic accumulation of phenylpropanoids in plant leaves led us to conclude that cyanobacterial inoculation correlates positively with plant growth promotion and stress tolerance in rice. Furthermore, the study helped in deciphering possible mechanisms underlying plant growth promotion and stress tolerance in rice following cyanobacterial inoculation and indicated the less explored avenue of cyanobacterial colonization in stress tolerance against abiotic stress. PMID:21732035

  20. Osmoregulation and salinity tolerance in the Antarctic midge, Belgica antarctica: seawater exposure confers enhanced tolerance to freezing and dehydration.

    PubMed

    Elnitsky, Michael A; Benoit, Joshua B; Lopez-Martinez, Giancarlo; Denlinger, David L; Lee, Richard E

    2009-09-01

    Summer storms along the Antarctic Peninsula can cause microhabitats of the terrestrial midge Belgica antarctica to become periodically inundated with seawater from tidal spray. As microhabitats dry, larvae may be exposed to increasing concentrations of seawater. Alternatively, as a result of melting snow or following rain, larvae may be immersed in freshwater for extended periods. The present study assessed the tolerance and physiological response of B. antarctica larvae to salinity exposure, and examined the effect of seawater acclimation on their subsequent tolerance of freezing, dehydration and heat shock. Midge larvae tolerated extended exposure to hyperosmotic seawater; nearly 50% of larvae survived a 10-day exposure to 1000 mOsm kg(-1) seawater and approximately 25% of larvae survived 6 days in 2000 mOsm kg(-1) seawater. Exposure to seawater drastically reduced larval body water content and increased hemolymph osmolality. By contrast, immersion in freshwater did not affect water content or hemolymph osmolality. Hyperosmotic seawater exposure, and the accompanying osmotic dehydration, resulted in a significant correlation between the rate of oxygen consumption and larval water content and induced the de novo synthesis and accumulation of several organic osmolytes. A 3-day exposure of larvae to hyperosmotic seawater increased freezing tolerance relative to freshwater-acclimated larvae. Even after rehydration, the freezing survival of larvae acclimated to seawater was greater than freshwater-acclimated larvae. Additionally, seawater exposure increased the subsequent tolerance of larvae to dehydration. Our results further illustrate the similarities between these related, yet distinct, forms of osmotic stress and add to the suite of physiological responses used by larvae to enhance survival in the harsh and unpredictable Antarctic environment. PMID:19684222

  1. Arbuscular mycorrhizal association enhances drought tolerance potential of promising bioenergy grass (Saccharum arundinaceum retz.).

    PubMed

    Mirshad, P P; Puthur, Jos T

    2016-07-01

    The influence of arbuscular mycorrhizal fungi (AMF) (Glomus spp.) on some physiological and biochemical characteristics of bioenergy grass Saccharum arundinaceum subjected to drought stress was studied. The symbiotic association of Glomus spp. was established with S. arundinaceum, a potential bioenergy grass as evident from the increase in percentage of root infection and distribution frequency of vesicles when compared with non-arbuscular mycorrhizal plants. AMF-treated plants exhibited an enhanced accumulation of osmolytes such as sugars and proline and also increased protein content under drought. AMF association significantly increased the accumulation of non-enzymatic antioxidants like phenols, ascorbate and glutathione as well as enhanced the activities of antioxidant enzymes such as SOD (superoxide dismutase), APX (ascorbate peroxidase) and GPX (guaiacol peroxidase) resulting in reduced lipid peroxidation in S. arundinaceum. AMF symbiosis also ameliorated the drought-induced reduction of total chlorophyll content and activities of photosystem I and II. The maximum quantum efficiency of PS II (F v/F m) and potential photochemical efficiency (F v/F o) were higher in AMF plants as compared to non-AMF plants under drought stress. These results indicate that AMF association alleviate drought stress in S. arundinaceum by the accumulation of osmolytes and non-enzymatic antioxidants and enhanced activities of antioxidant enzymes, and hence, the photosynthetic efficiency is improved resulting in increased biomass production. AMF association with energy grasses also improves the acclimatization of S. arundinaceum for growing in marginal lands of drought-affected soils. PMID:27329476

  2. Gene therapy enhances chemotherapy tolerance and efficacy in glioblastoma patients

    PubMed Central

    Adair, Jennifer E.; Johnston, Sandra K.; Mrugala, Maciej M.; Beard, Brian C.; Guyman, Laura A.; Baldock, Anne L.; Bridge, Carly A.; Hawkins-Daarud, Andrea; Gori, Jennifer L.; Born, Donald E.; Gonzalez-Cuyar, Luis F.; Silbergeld, Daniel L.; Rockne, Russell C.; Storer, Barry E.; Rockhill, Jason K.; Swanson, Kristin R.; Kiem, Hans-Peter

    2014-01-01

    BACKGROUND. Temozolomide (TMZ) is one of the most potent chemotherapy agents for the treatment of glioblastoma. Unfortunately, almost half of glioblastoma tumors are TMZ resistant due to overexpression of methylguanine methyltransferase (MGMThi). Coadministration of O6-benzylguanine (O6BG) can restore TMZ sensitivity, but causes off-target myelosuppression. Here, we conducted a prospective clinical trial to test whether gene therapy to confer O6BG resistance in hematopoietic stem cells (HSCs) improves chemotherapy tolerance and outcome. METHODS. We enrolled 7 newly diagnosed glioblastoma patients with MGMThi tumors. Patients received autologous gene-modified HSCs following single-agent carmustine administration. After hematopoietic recovery, patients underwent O6BG/TMZ chemotherapy in 28-day cycles. Serial blood samples and tumor images were collected throughout the study. Chemotherapy tolerance was determined by the observed myelosuppression and recovery following each cycle. Patient-specific biomathematical modeling of tumor growth was performed. Progression-free survival (PFS) and overall survival (OS) were also evaluated. RESULTS. Gene therapy permitted a significant increase in the mean number of tolerated O6BG/TMZ cycles (4.4 cycles per patient, P < 0.05) compared with historical controls without gene therapy (n = 7 patients, 1.7 cycles per patient). One patient tolerated an unprecedented 9 cycles and demonstrated long-term PFS without additional therapy. Overall, we observed a median PFS of 9 (range 3.5–57+) months and OS of 20 (range 13–57+) months. Furthermore, biomathematical modeling revealed markedly delayed tumor growth at lower cumulative TMZ doses in study patients compared with patients that received standard TMZ regimens without O6BG. CONCLUSION. These data support further development of chemoprotective gene therapy in combination with O6BG and TMZ for the treatment of glioblastoma and potentially other tumors with overexpression of MGMT. TRIAL

  3. Enhanced glucose tolerance by intravascularly administered piceatannol in freely moving healthy rats.

    PubMed

    Oritani, Yukihiro; Okitsu, Teru; Nishimura, Eisaku; Sai, Masahiko; Ito, Tatsuhiko; Takeuchi, Shoji

    2016-02-12

    Piceatannol is a phytochemical in the seeds of passion fruit that has a hypoglycemic effect when orally administered. To elucidate the contribution of intact and metabolites of piceatannol after gastro-intestinal absorption to hypoglycemic effect, we examined the influence of piceatannol and isorhapontigenin on blood glucose concentrations during fasting and glucose tolerance tests by administering them intravascularly to freely moving healthy rats. We found that intravascularly administered piceatannol reduced the blood glucose concentrations during both fasting and glucose tolerance tests, but isorhapontigenin did not during either of them. Furthermore, we found that piceatannol increased the insulinogenic index during glucose tolerance tests and that piceatannol had no influence on insulin sensitivity by performing hyperinsulinemic euglycemic clamping tests. These results suggest that piceatannol orally intaken may enhance glucose tolerance by the effect of intact piceatannol through enhanced early-phase secretion of insulin. Therefore, oral intake of piceatannol might contribute to proper control of postprandial glycemic excursions in healthy subjects. PMID:26773506

  4. Laminarin modulates the chloroplast antioxidant system to enhance abiotic stress tolerance partially through the regulation of the defensin-like gene expression.

    PubMed

    Wu, Yi-Ru; Lin, Yi-Chen; Chuang, Huey-Wen

    2016-06-01

    Algae wall polysaccharide, laminarin (Lam), has an established role on induction of plant disease resistance. In this study, application of Lam increased Arabidopsis fresh weight and enhanced tolerance to salt and heat stress by stabilizing chloroplast under adverse environment. Transcriptome analysis indicated that, in addition to induced a large number of genes associated with the host defense, genes involved in the regulation of abiotic stress tolerance mostly the heat stress response constituted the largest group of the up-regulated genes. Lam induced expression of IRT1, ZIP8, and copper transporters involved in transport of Fe, Zn, Cu ions associated with the activity of chloroplast antioxidant system. Lam also up-regulated genes involved in the synthesis of terpenoid, a plastidial-derived secondary metabolite with antioxidant activity. Overexpression of a Lam-induced defensin like 202 (DEFL202) resulted in increased chloroplast stability under salt stress and increased plant growth activity after heat stress. Expression of antioxidant enzymes including SOD and ascorbate peroxidase (APX), photosystem PsbA-D1 and ABA-dependent responsive to desiccation 22 (RD22) was induced to higher levels in the transgenic seedlings. In sum, our results suggest that Lam is an potent inducer for induction of chloroplastic antioxidant activity. Lam affect plant abiotic stress tolerance partially through regulation of the DEFL-mediated pathway. PMID:27095402

  5. Nanostructures for peroxidases

    PubMed Central

    Carmona-Ribeiro, Ana M.; Prieto, Tatiana; Nantes, Iseli L.

    2015-01-01

    Peroxidases are enzymes catalyzing redox reactions that cleave peroxides. Their active redox centers have heme, cysteine thiols, selenium, manganese, and other chemical moieties. Peroxidases and their mimetic systems have several technological and biomedical applications such as environment protection, energy production, bioremediation, sensors and immunoassays design, and drug delivery devices. The combination of peroxidases or systems with peroxidase-like activity with nanostructures such as nanoparticles, nanotubes, thin films, liposomes, micelles, nanoflowers, nanorods and others is often an efficient strategy to improve catalytic activity, targeting, and reusability. PMID:26389124

  6. Nanostructures for peroxidases.

    PubMed

    Carmona-Ribeiro, Ana M; Prieto, Tatiana; Nantes, Iseli L

    2015-01-01

    Peroxidases are enzymes catalyzing redox reactions that cleave peroxides. Their active redox centers have heme, cysteine thiols, selenium, manganese, and other chemical moieties. Peroxidases and their mimetic systems have several technological and biomedical applications such as environment protection, energy production, bioremediation, sensors and immunoassays design, and drug delivery devices. The combination of peroxidases or systems with peroxidase-like activity with nanostructures such as nanoparticles, nanotubes, thin films, liposomes, micelles, nanoflowers, nanorods and others is often an efficient strategy to improve catalytic activity, targeting, and reusability. PMID:26389124

  7. Peroxidase(s) in Environment Protection

    PubMed Central

    Bansal, Neelam; Kanwar, Shamsher S.

    2013-01-01

    Industrial discharges of untreated effluents into water bodies and emissions into air have deteriorated the quality of water and air, respectively. The huge amount of pollutants derived from industrial activities represents a threat for the environment and ecologic equilibrium. Phenols and halogenated phenols, polycyclic aromatic hydrocarbons (PAH), endocrine disruptive chemicals (EDC), pesticides, dioxins, polychlorinated biphenyls (PCB), industrial dyes, and other xenobiotics are among the most important pollutants. Peroxidases are enzymes that are able to transform a variety of compounds following a free radical mechanism, thereby yielding oxidized or polymerized products. The peroxidase transformation of these pollutants is accompanied by a reduction in their toxicity, due to loss of biological activity, reduction in the bioavailability, or the removal from aqueous phase, especially when the pollutant is found in water. The review describes the sources of peroxidases, the reactions catalyzed by them, and their applications in the management of pollutants in the environment. PMID:24453894

  8. The Multifarious PGPR Serratia marcescens CDP-13 Augments Induced Systemic Resistance and Enhanced Salinity Tolerance of Wheat (Triticum aestivum L.)

    PubMed Central

    Singh, Rajnish Prakash; Jha, Prabhat Nath

    2016-01-01

    The present study demonstrates the plant growth promoting (PGP) potential of a bacterial isolate CDP-13 isolated from ‘Capparis decidua’ plant, and its ability to protect plants from the deleterious effect of biotic and abiotic stressors. Based on 16S rRNA gene sequence analysis, the isolate was identified as Serratia marcescens. Among the PGP traits, the isolate was found to be positive for ACC deaminase activity, phosphate solubilization, production of siderophore, indole acetic acid production, nitrogen fixation, and ammonia production. CDP-13 showed growth at an increased salt (NaCl) concentration of up to 6%, indicating its potential to survive and associate with plants growing in saline soil. The inoculation of S. marcescens enhanced the growth of wheat plant under salinity stress (150–200 mM). It significantly reduced inhibition of plant growth (15 to 85%) caused by salt stressors. Application of CDP-13 also modulated concentration (20 to 75%) of different osmoprotectants (proline, malondialdehyde, total soluble sugar, total protein content, and indole acetic acid) in plants suggesting its role in enabling plants to tolerate salt stressors. In addition, bacterial inoculation also reduced the disease severity caused by fungal infection, which illustrated its ability to confer induced systemic resistance (ISR) in host plants. Treatment of wheat plants with the test organism caused alteration in anti-oxidative enzymes activities (Superoxide dismutase, Catalase, and Peroxidase) under various salinity levels, and therefore minimizes the salinity-induced oxidative damages to the plants. Colonization efficiency of strain CDP-13 was confirmed by CFU count, epi-fluorescence microscopy, and ERIC-PCR-based DNA fingerprinting approach. Hence, the study indicates that bacterium CDP-13 enhances plant growth, and has potential for the amelioration of salinity stress in wheat plants. Likewise, the results also provide insights into biotechnological approaches to using

  9. The Multifarious PGPR Serratia marcescens CDP-13 Augments Induced Systemic Resistance and Enhanced Salinity Tolerance of Wheat (Triticum aestivum L.).

    PubMed

    Singh, Rajnish Prakash; Jha, Prabhat Nath

    2016-01-01

    The present study demonstrates the plant growth promoting (PGP) potential of a bacterial isolate CDP-13 isolated from 'Capparis decidua' plant, and its ability to protect plants from the deleterious effect of biotic and abiotic stressors. Based on 16S rRNA gene sequence analysis, the isolate was identified as Serratia marcescens. Among the PGP traits, the isolate was found to be positive for ACC deaminase activity, phosphate solubilization, production of siderophore, indole acetic acid production, nitrogen fixation, and ammonia production. CDP-13 showed growth at an increased salt (NaCl) concentration of up to 6%, indicating its potential to survive and associate with plants growing in saline soil. The inoculation of S. marcescens enhanced the growth of wheat plant under salinity stress (150-200 mM). It significantly reduced inhibition of plant growth (15 to 85%) caused by salt stressors. Application of CDP-13 also modulated concentration (20 to 75%) of different osmoprotectants (proline, malondialdehyde, total soluble sugar, total protein content, and indole acetic acid) in plants suggesting its role in enabling plants to tolerate salt stressors. In addition, bacterial inoculation also reduced the disease severity caused by fungal infection, which illustrated its ability to confer induced systemic resistance (ISR) in host plants. Treatment of wheat plants with the test organism caused alteration in anti-oxidative enzymes activities (Superoxide dismutase, Catalase, and Peroxidase) under various salinity levels, and therefore minimizes the salinity-induced oxidative damages to the plants. Colonization efficiency of strain CDP-13 was confirmed by CFU count, epi-fluorescence microscopy, and ERIC-PCR-based DNA fingerprinting approach. Hence, the study indicates that bacterium CDP-13 enhances plant growth, and has potential for the amelioration of salinity stress in wheat plants. Likewise, the results also provide insights into biotechnological approaches to using PGPR

  10. Preparation of a Superhydrophobic and Peroxidase-like Activity Array Chip for H2O2 Sensing by Surface-Enhanced Raman Scattering.

    PubMed

    Yu, Zhi; Park, Yeonju; Chen, Lei; Zhao, Bing; Jung, Young Mee; Cong, Qian

    2015-10-28

    In this paper, we propose a novel and simple method for preparing a dual-biomimetic functional array possessing both superhydrophobic and peroxidase-like activity that can be used for hydrogen peroxide (H2O2) sensing. The proposed method is an integration innovation that combines the above two properties and surface-enhanced Raman scattering (SERS). We integrated a series of well-ordered arrays of Au points (d = 1 mm) onto a superhydrophobic copper (Cu)/silver (Ag) surface by replicating an arrayed molybdenum template. Instead of using photoresists and the traditional lithography method, we utilized a chemical etching method (a substitution reaction between Cu and HAuCl4) with a Cu/Ag superhydrophobic surface as the barrier layer, which has the benefit of water repellency. The as-prepared Au points were observed to possess peroxidase-like activity, allowing for catalytic oxidation of the chromogenic molecule o-phenylenediamine dihydrochloride (OPD). Oxidation was evidenced by a color change in the presence of H2O2, which allows the array chip to act as an H2O2 sensor. In this study, the water repellency of the superhydrophobic surface was used to fabricate the array chip and increase the local reactant concentration during the catalytic reaction. As a result, the catalytic reaction occurred when only 2 μL of an aqueous sample (OPD/H2O2) was placed onto the Au point, and the enzymatic product, 2,3-diaminophenazine, showed a SERS signal distinguishable from that of OPD after mixing with 2 μL of colloidal Au. Using the dual-biomimetic functional array chip, quantitative analysis of H2O2 was performed by observing the change in the SERS spectra, which showed a concentration-dependent behavior for H2O2. This method allows for the detection of H2O2 at concentrations as low as 3 pmol per 2 μL of sample, which is a considerable advantage in H2O2 analysis. The as-prepared substrate was convenient for H2O2 detection because only a small amount of sample was required in

  11. Bacterial extracellular lignin peroxidase

    DOEpatents

    Crawford, Donald L.; Ramachandra, Muralidhara

    1993-01-01

    A newly discovered lignin peroxidase enzyme is provided. The enzyme is obtained from a bacterial source and is capable of degrading the lignin portion of lignocellulose in the presence of hydrogen peroxide. The enzyme is extracellular, oxidative, inducible by lignin, larch wood xylan, or related substrates and capable of attacking certain lignin substructure chemical bonds that are not degradable by fungal lignin peroxidases.

  12. Overexpression of a Brassica campestris HSP70 in tobacco confers enhanced tolerance to heat stress.

    PubMed

    Wang, Xiaorong; Yan, Bin; Shi, Min; Zhou, Wei; Zekria, David; Wang, Huizhong; Kai, Guoyin

    2016-05-01

    Heat shock proteins (HSPs) exist extensively in eukaryotes and are conserved molecular chaperones with important contribution to plant's survival under environmental stresses. Here, the cloning and characterization of one complementary DNA (cDNA) designated as BcHSP70 from young seedlings of Brassica campestris were reported in the present work. Bioinformatic analysis revealed that BcHSP70 belongs to the plant HSP gene family and had the closest relationship with HSP70-4 from Arabidopsis thaliana. Constitutive overexpression of BcHSP70 in tobacco obviously conferred tolerance to heat stress by affecting different plant physiological parameters. In our study, transgenic tobaccos exhibited higher chlorophyll content than wild-type control when exposed to heat stress. Superoxide dismutase (SOD) and peroxidase (POD) activities, which were helpful to decrease the damage to the membrane system, were significantly higher in transformants compared to wild-type lines. Meanwhile, lower comparative electrical conductivity and malondialdehyde (MDA) content and higher proline and soluble sugar accumulation were found in transgenic tobaccos than in wild-type lines. All these above results indicated that this isolated BcHSP70 cDNA owned the ability to improve the tolerance to heat stress in transgenic tobacco, which provides helpful information and good basement to culture new robust B. campestris variety resistant to high-temperature stress by molecular breeding in the future. PMID:26298102

  13. NMR Studies of Peroxidases.

    NASA Astrophysics Data System (ADS)

    Veitch, Nigel Charles

    Available from UMI in association with The British Library. Requires signed TDF. Peroxidases are a haem-containing group of enzymes with a wide diversity of function within biological systems. While a common characteristic is the ability to catalyse the conversion of hydrogen peroxide to water, it is the accompanying processes of hormone synthesis and degradation which have generated such a high level of interest. However, information at the molecular level is limited to a single well-resolved crystal structure, that of yeast cytochrome c peroxidase. This thesis presents a strategy for the investigation of peroxidase structure and function based on proton nuclear magnetic resonance spectroscopy, a technique which has the ability to address aspects of both protein structure and protein dynamics in solution. The application of one- and two-dimensional NMR techniques has been developed in the context of plant peroxidases, notably the isoenzyme HRP-C derived from the horseradish root. Characterisation of the proton NMR spectra of HRP -C in resting and ligated states provided new information enabling the structure of the binding site for aromatic donor molecules, such as indole-3-propionic, ferulic and benzhydroxamic acids, to be resolved. In order to overcome difficulties encountered with a protein of the complexity of peroxidase, additional information was obtained from chemical shift parameters and the use of peroxidase variants produced by site-directed mutagenesis. A comparative study using NMR spectroscopy was undertaken for wild-type recombinant HRP-C expressed in Escherichia coli, and two protein variants with substitutions made to residues located on the distal side of the haem pocket, Phe41 to Val and Arg38 to Lys. NMR analyses of a plant peroxidase from barley grains and the fungal peroxidase from Coprinus cinereus were also successful using methods conceived with HRP-C. Examination of three specifically constructed recombinant protein variants of C. cinereus

  14. Enhancement of drought stress tolerance in crops by plant growth promoting rhizobacteria.

    PubMed

    Vurukonda, Sai Shiva Krishna Prasad; Vardharajula, Sandhya; Shrivastava, Manjari; SkZ, Ali

    2016-03-01

    Drought is one of the major constraints on agricultural productivity worldwide and is likely to further increase. Several adaptations and mitigation strategies are required to cope with drought stress. Plant growth promoting rhizobacteria (PGPR) could play a significant role in alleviation of drought stress in plants. These beneficial microorganisms colonize the rhizosphere/endo-rhizosphere of plants and impart drought tolerance by producing exopolysaccharides (EPS), phytohormones, 1-aminocyclopropane- 1-carboxylate (ACC) deaminase, volatile compounds, inducing accumulation of osmolytes, antioxidants, upregulation or down regulation of stress responsive genes and alteration in root morphology in acquisition of drought tolerance. The term Induced Systemic Tolerance (IST) was coined for physical and chemical changes induced by microorganisms in plants which results in enhanced tolerance to drought stresses. In the present review we elaborate on the role of PGPR in helping plants to cope with drought stress. PMID:26856449

  15. Insights into how nucleotide supplements enhance the peroxidase-mimicking DNAzyme activity of the G-quadruplex/hemin system.

    PubMed

    Stefan, Loic; Denat, Franck; Monchaud, David

    2012-09-01

    Since the initial discovery of the catalytic capability of short DNA fragments, this peculiar enzyme-like property (termed DNAzyme) has continued to garner much interest in the scientific community because of the virtually unlimited applications in developing new molecular devices. Alongside the exponential rise in the number of DNAzyme applications in the last past years, the search for convenient ways to improve its overall efficiency has only started to emerge. Credence has been lent to this strategy by the recent demonstration that the quadruplex-based DNAzyme proficiency can be enhanced by ATP supplements. Herein, we have made a further leap along this path, trying first of all to decipher the actual DNAzyme catalytic cycle (to gain insights into the steps ATP may influence), and subsequently investigating in detail the influence of all the parameters that govern the catalytic efficiency. We have extended this study to other nucleotides and quadruplexes, thus demonstrating the versatility and broad applicability of such an approach. The defined exquisitely efficient DNAzyme protocols were exploited to highlight the enticing advantages of this method via a 96-well plate experiment that enables the detection of nanomolar DNA concentrations in real-time with the naked-eye (see movie as Supplementary Data). PMID:22730286

  16. Overexpression of quinone reductase from Salix matsudana Koidz enhances salt tolerance in transgenic Arabidopsis thaliana.

    PubMed

    Song, Xixi; Fang, Jie; Han, Xiaojiao; He, Xuelian; Liu, Mingying; Hu, Jianjun; Zhuo, Renying

    2016-01-15

    Quinone reductase (QR) is an oxidative-related gene and few studies have focused on its roles concerning salt stress tolerance in plants. In this study, we cloned and analyzed the QR gene from Salix matsudana, a willow with tolerance of moderate salinity. The 612-bp cDNA corresponding to SmQR encodes 203 amino acids. Expression of SmQR in Escherichia coli cells enhanced their tolerance under salt stress. In addition, transgenic Arabidopsis thaliana lines overexpressing SmQR exhibited higher salt tolerance as compared with WT, with higher QR activity and antioxidant enzyme activity as well as higher chlorophyll content, lower methane dicarboxylic aldehyde (MDA) content and electric conductivity under salt stress. Nitro blue tetrazolium (NBT) and 3,3'-diaminobenzidine (DAB) staining also indicated that the transgenic plants accumulated less reactive oxygen species compared to WT when exposed to salt stress. Overall, our results suggested that SmQR plays a significant role in salt tolerance and that this gene may be useful for biotechnological development of plants with improved tolerance of salinity. PMID:26541063

  17. Dispersion tolerance enhancement using an improved offset-QAM OFDM scheme.

    PubMed

    Zhao, Jian; Townsend, Paul D

    2015-06-29

    Discrete-Fourier transform (DFT) based offset quadrature amplitude modulation (offset-QAM) orthogonal frequency division multiplexing (OFDM) without cyclic prefix (CP) was shown to offer a dispersion tolerance the same as that of conventional OFDM with ~20% CP overhead. In this paper, we analytically study the fundamental mechanism limiting the dispersion tolerance of this conventional scheme. It is found that the signal and the crosstalk from adjacent subcarriers, which are orthogonal with π/2 phase difference at back to back, can be in-phase when the dispersion increases to a certain value. We propose a novel scheme to overcome this limitation and significantly improve the dispersion tolerance to that of one subcarrier. Simulations show that the proposed scheme can support a 224-Gb/s polarization-division-multiplexed offset-4QAM OFDM signal over 160,000 ps/nm without any CP under 128 subcarriers, and this tolerance scales with the square of the number of subcarriers. It is also shown that this scheme exhibits advantages of greatly enhanced spectral efficiency, larger dispersion tolerance, and/or reduced complexity compared to the conventional CP-OFDM and reduced-guard-interval OFDM using frequency domain equalization. PMID:26191771

  18. Ectopic expression of Arabidopsis RCI2A gene contributes to cold tolerance in tomato.

    PubMed

    Sivankalyani, Velu; Geetha, Mahalingam; Subramanyam, Kondeti; Girija, Shanmugam

    2015-04-01

    Cold is a major stress that limits the quality and productivity of economically important crops such as tomato (Solanum lycopersicum L.). Generating a cold-stress-tolerant tomato by expressing cold-inducible genes would increase agricultural strategies. Rare cold-inducible 2a (RCI2A) is expressed in Arabidopsis, but its molecular function during cold stress is not fully understood. Here we ectopically expressed Arabidopsis RCI2A in transgenic tomato to evaluate tolerance to cold stress without altering agronomic traits. Biochemical and physiological study demonstrated that expression of RCI2A in transgenic tomato enhanced the activity of peroxidase and ascorbate peroxidase (APX) and reduced the accumulation of H2O2, alleviated lipid peroxidation, increased the accumulation of chlorophyll, reduced chilling-induced membrane damage, retained relative water content and enhanced cold tolerance. A motif search revealed that the motifs of photosystem II (PSII) phosphoproteins PsbJ and PsbH and reaction-center proteins PsbL and PsbK were common to cold-inducible RCI2A and peroxidase proteins RCI3A, tomato peroxidase (TPX1), TPX2, tomato ascorbate peroxidase (APX1), and horseradish peroxidase (HRP-c). In addition to membrane protection, RCI2A may cross talk with PSII-associated proteins or peroxidase family enzymes in response to cold stress. Our findings may strengthen the understanding of the molecular function of RCI2A in cold-stress tolerance. RCI2A could be used to improve abiotic stress tolerance in agronomic crops. PMID:25260337

  19. Ky-2, a Histone Deacetylase Inhibitor, Enhances High-Salinity Stress Tolerance in Arabidopsis thaliana.

    PubMed

    Sako, Kaori; Kim, Jong-Myong; Matsui, Akihiro; Nakamura, Kotaro; Tanaka, Maho; Kobayashi, Makoto; Saito, Kazuki; Nishino, Norikazu; Kusano, Miyako; Taji, Teruaki; Yoshida, Minoru; Seki, Motoaki

    2016-04-01

    Adaptation to environmental stress requires genome-wide changes in gene expression. Histone modifications are involved in gene regulation, but the role of histone modifications under environmental stress is not well understood. To reveal the relationship between histone modification and environmental stress, we assessed the effects of inhibitors of histone modification enzymes during salinity stress. Treatment with Ky-2, a histone deacetylase inhibitor, enhanced high-salinity stress tolerance in Arabidopsis. We confirmed that Ky-2 possessed inhibition activity towards histone deacetylases by immunoblot analysis. To investigate how Ky-2 improved salt stress tolerance, we performed transcriptome and metabolome analysis. These data showed that the expression of salt-responsive genes and salt stress-related metabolites were increased by Ky-2 treatment under salinity stress. A mutant deficient inAtSOS1(Arabidopis thaliana SALT OVERLY SENSITIVE 1), which encodes an Na(+)/H(+)antiporter and was among the up-regulated genes, lost the salinity stress tolerance conferred by Ky-2. We confirmed that acetylation of histone H4 atAtSOS1was increased by Ky-2 treatment. Moreover, Ky-2 treatment decreased the intracellular Na(+)accumulation under salinity stress, suggesting that enhancement of SOS1-dependent Na(+)efflux contributes to increased high-salinity stress tolerance caused by Ky-2 treatment. PMID:26657894

  20. Interaction of brassinosteroids and polyamines enhances copper stress tolerance in raphanus sativus.

    PubMed

    Choudhary, Sikander Pal; Oral, H Volkan; Bhardwaj, Renu; Yu, Jing-Quan; Tran, Lam-Son Phan

    2012-09-01

    Brassinosteroids (BRs) and polyamines (PAs) regulate various responses to abiotic stress, but their involvement in the regulation of copper (Cu) homeostasis in plants exposed to toxic levels of Cu is poorly understood. This study provides an analysis of the effects of exogenously applied BRs and PAs on radish (Raphanus sativus) plants exposed to toxic concentrations of Cu. The interaction of 24-epibrassinolide (EBR, an active BR) and spermidine (Spd, an active PA) on gene expression and the physiology of radish plants resulted in enhanced tolerance to Cu stress. Results indicated that the combined application of EBR and Spd modulated the expression of genes encoding PA enzymes and genes that impact the metabolism of indole-3-acetic acid (IAA) and abscisic acid (ABA) resulting in enhanced Cu stress tolerance. Altered expression of genes implicated in Cu homeostasis appeared to be the main effect of EBR and Spd leading to Cu stress alleviation in radish. Ion leakage, in vivo imaging of H(2)O(2), comet assay, and improved tolerance of Cu-sensitive yeast strains provided further evidence for the ability of EBR and Spd to improve Cu tolerance significantly. The study indicates that co-application of EBR and Spd is an effective approach for Cu detoxification and the maintenance of Cu homeostasis in plants. Therefore, the use of these compounds in agricultural production systems should be explored. PMID:22915739

  1. Interaction of Brassinosteroids and Polyamines Enhances Copper Stress Tolerance in Raphanus Sativus

    PubMed Central

    Choudhary, Sikander Pal; Yu, Jing-Quan; Tran, Lam-Son Phan

    2012-01-01

    Brassinosteroids (BRs) and polyamines (PAs) regulate various responses to abiotic stress, but their involvement in the regulation of copper (Cu) homeostasis in plants exposed to toxic levels of Cu is poorly understood. This study provides an analysis of the effects of exogenously applied BRs and PAs on radish (Raphanus sativus) plants exposed to toxic concentrations of Cu. The interaction of 24-epibrassinolide (EBR, an active BR) and spermidine (Spd, an active PA) on gene expression and the physiology of radish plants resulted in enhanced tolerance to Cu stress. Results indicated that the combined application of EBR and Spd modulated the expression of genes encoding PA enzymes and genes that impact the metabolism of indole-3-acetic acid (IAA) and abscisic acid (ABA) resulting in enhanced Cu stress tolerance. Altered expression of genes implicated in Cu homeostasis appeared to be the main effect of EBR and Spd leading to Cu stress alleviation in radish. Ion leakage, in vivo imaging of H2O2, comet assay, and improved tolerance of Cu-sensitive yeast strains provided further evidence for the ability of EBR and Spd to improve Cu tolerance significantly. The study indicates that co-application of EBR and Spd is an effective approach for Cu detoxification and the maintenance of Cu homeostasis in plants. Therefore, the use of these compounds in agricultural production systems should be explored. PMID:22915739

  2. Manipulating stomatal density enhances drought tolerance without deleterious effect on nutrient uptake.

    PubMed

    Hepworth, Christopher; Doheny-Adams, Timothy; Hunt, Lee; Cameron, Duncan D; Gray, Julie E

    2015-10-01

    Manipulation of stomatal density was investigated as a potential tool for enhancing drought tolerance or nutrient uptake. Drought tolerance and soil water retention were assessed using Arabidopsis epidermal patterning factor mutants manipulated to have increased or decreased stomatal density. Root nutrient uptake via mass flow was monitored under differing plant watering regimes using nitrogen-15 ((15) N) isotope and mass spectrometry. Plants with less than half of their normal complement of stomata, and correspondingly reduced levels of transpiration, conserve soil moisture and are highly drought tolerant but show little or no reduction in shoot nitrogen concentrations especially when water availability is restricted. By contrast, plants with over twice the normal density of stomata have a greater capacity for nitrogen uptake, except when water availability is restricted. We demonstrate the possibility of producing plants with reduced transpiration which have increased drought tolerance, with little or no loss of nutrient uptake. We demonstrate that increasing transpiration can enhance nutrient uptake when water is plentiful. PMID:26268722

  3. A Novel α/β-Hydrolase Gene IbMas Enhances Salt Tolerance in Transgenic Sweetpotato

    PubMed Central

    Song, Xuejin; He, Shaozhen; Liu, Qingchang

    2014-01-01

    Salt stress is one of the major environmental stresses in agriculture worldwide and affects crop productivity and quality. The development of crops with elevated levels of salt tolerance is therefore highly desirable. In the present study, a novel maspardin gene, named IbMas, was isolated from salt-tolerant sweetpotato (Ipomoea batatas (L.) Lam.) line ND98. IbMas contains maspardin domain and belongs to α/β-hydrolase superfamily. Expression of IbMas was up-regulated in sweetpotato under salt stress and ABA treatment. The IbMas-overexpressing sweetpotato (cv. Shangshu 19) plants exhibited significantly higher salt tolerance compared with the wild-type. Proline content was significantly increased, whereas malonaldehyde content was significantly decreased in the transgenic plants. The activities of superoxide dismutase (SOD) and photosynthesis were significantly enhanced in the transgenic plants. H2O2 was also found to be significantly less accumulated in the transgenic plants than in the wild-type. Overexpression of IbMas up-regulated the salt stress responsive genes, including pyrroline-5-carboxylate synthase, pyrroline-5-carboxylate reductase, SOD, psbA and phosphoribulokinase genes, under salt stress. These findings suggest that overexpression of IbMas enhances salt tolerance of the transgenic sweetpotato plants by regulating osmotic balance, protecting membrane integrity and photosynthesis and increasing reactive oxygen species scavenging capacity. PMID:25501819

  4. Physiological, anatomical and transcriptional alterations in a rice mutant leading to enhanced water stress tolerance.

    PubMed

    Lima, John Milton; Nath, Manoj; Dokku, Prasad; Raman, K V; Kulkarni, K P; Vishwakarma, C; Sahoo, S P; Mohapatra, U B; Mithra, S V Amitha; Chinnusamy, V; Robin, S; Sarla, N; Seshashayee, M; Singh, K; Singh, A K; Singh, N K; Sharma, R P; Mohapatra, T

    2015-01-01

    Water stress is one of the most severe constraints to crop productivity. Plants display a variety of physiological and biochemical responses both at the cellular and whole organism level upon sensing water stress. Leaf rolling, stomatal closure, deeper root penetration, higher relative water content (RWC) and better osmotic adjustment are some of the mechanisms that plants employ to overcome water stress. In the current study, we report a mutant, enhanced water stress tolerant1 (ewst1) with enhanced water stress tolerance, identified from the ethyl methanesulfonate-induced mutant population of rice variety Nagina22 by field screening followed by withdrawal of irrigation in pots and hydroponics (PEG 6000). Though ewst1 was morphologically similar to the wild type (WT) for 35 of the 38 morphological descriptors (except chalky endosperm/expression of white core, decorticated grain colour and grain weight), it showed enhanced germination in polyethylene glycol-infused medium. It exhibited increase in maximum root length without any significant changes in its root weight, root volume and total root number on crown when compared with the WT under stress in PVC tube experiment. It also showed better performance for various physiological parameters such as RWC, cell membrane stability and chlorophyll concentration upon water stress in a pot experiment. Root anatomy and stomatal microscopic studies revealed changes in the number of xylem and phloem cells, size of central meta-xylem and number of closed stomata in ewst1. Comparative genome-wide transcriptome analysis identified genes related to exocytosis, secondary metabolites, tryptophan biosynthesis, protein phosphorylation and other signalling pathways to be playing a role in enhanced response to water stress in ewst1. The possible involvement of a candidate gene with respect to the observed morpho-physiological and transcriptional changes and its role in stress tolerance are discussed. The mutant identified and

  5. Physiological, anatomical and transcriptional alterations in a rice mutant leading to enhanced water stress tolerance

    PubMed Central

    Lima, John Milton; Nath, Manoj; Dokku, Prasad; Raman, K. V.; Kulkarni, K. P.; Vishwakarma, C.; Sahoo, S. P.; Mohapatra, U. B.; Mithra, S. V. Amitha; Chinnusamy, V.; Robin, S.; Sarla, N.; Seshashayee, M.; Singh, K.; Singh, A. K.; Singh, N. K.; Sharma, R. P.; Mohapatra, T.

    2015-01-01

    Water stress is one of the most severe constraints to crop productivity. Plants display a variety of physiological and biochemical responses both at the cellular and whole organism level upon sensing water stress. Leaf rolling, stomatal closure, deeper root penetration, higher relative water content (RWC) and better osmotic adjustment are some of the mechanisms that plants employ to overcome water stress. In the current study, we report a mutant, enhanced water stress tolerant1 (ewst1) with enhanced water stress tolerance, identified from the ethyl methanesulfonate-induced mutant population of rice variety Nagina22 by field screening followed by withdrawal of irrigation in pots and hydroponics (PEG 6000). Though ewst1 was morphologically similar to the wild type (WT) for 35 of the 38 morphological descriptors (except chalky endosperm/expression of white core, decorticated grain colour and grain weight), it showed enhanced germination in polyethylene glycol-infused medium. It exhibited increase in maximum root length without any significant changes in its root weight, root volume and total root number on crown when compared with the WT under stress in PVC tube experiment. It also showed better performance for various physiological parameters such as RWC, cell membrane stability and chlorophyll concentration upon water stress in a pot experiment. Root anatomy and stomatal microscopic studies revealed changes in the number of xylem and phloem cells, size of central meta-xylem and number of closed stomata in ewst1. Comparative genome-wide transcriptome analysis identified genes related to exocytosis, secondary metabolites, tryptophan biosynthesis, protein phosphorylation and other signalling pathways to be playing a role in enhanced response to water stress in ewst1. The possible involvement of a candidate gene with respect to the observed morpho-physiological and transcriptional changes and its role in stress tolerance are discussed. The mutant identified and

  6. Characterization of leaf apoplastic peroxidases and metabolites in Vigna unguiculata in response to toxic manganese supply and silicon.

    PubMed

    Führs, Hendrik; Götze, Stefanie; Specht, André; Erban, Alexander; Gallien, Sébastien; Heintz, Dimitri; Van Dorsselaer, Alain; Kopka, Joachim; Braun, Hans-Peter; Horst, Walter J

    2009-01-01

    Previous work suggested that the apoplastic phenol composition and its interaction with apoplastic class III peroxidases (PODs) are decisive in the development or avoidance of manganese (Mn) toxicity in cowpea (Vigna unguiculata L.). This study characterizes apoplastic PODs with particular emphasis on the activities of specific isoenzymes and their modulation by phenols in the Mn-sensitive cowpea cultivar TVu 91 as affected by Mn and silicon (Si) supply. Si reduced Mn-induced toxicity symptoms without affecting the Mn uptake. Blue Native-PAGE combined with Nano-LC-MS/MS allowed identification of a range of POD isoenzymes in the apoplastic washing fluid (AWF). In Si-treated plants Mn-mediated induction of POD activity was delayed. Four POD isoenzymes eluted from the BN gels catalysed both H(2)O(2)-consuming and H(2)O(2)-producing activity with pH optima at 6.5 and 5.5, respectively. Four phenols enhanced NADH-peroxidase activity of these isoenzymes in the presence of Mn(2+) (p-coumaric=vanillic>benzoic>ferulic acid). p-Coumaric acid-enhanced NADH-peroxidase activity was inhibited by ferulic acid (50%) and five other phenols (50-90%). An independent component analysis (ICA) of the total and apoplastic GC-MS-based metabolome profile showed that Mn, Si supply, and the AWF fraction (AWF(H(2)O), AWF(NaCl)) significantly changed the metabolite composition. Extracting non-polar metabolites from the AWF allowed the identification of phenols. Predominantly NADH-peroxidase activity-inhibiting ferulic acid appeared to be down-regulated in Mn-sensitive (+Mn, -Si) and up-regulated in Mn-tolerant (+Si) leaf tissue. The results presented here support the previously hypothesized role of apoplastic NADH-peroxidase and its activity-modulating phenols in Mn toxicity and Si-enhanced Mn tolerance. PMID:19286915

  7. A one-pot and in situ synthesis of CuS-graphene nanosheet composites with enhanced peroxidase-like catalytic activity.

    PubMed

    Nie, Guangdi; Zhang, Liang; Lu, Xiaofeng; Bian, Xiujie; Sun, Weining; Wang, Ce

    2013-10-14

    CuS-graphene nanosheet (GNS) composites with well-defined morphology have been successfully fabricated via a simple one-pot hydrothermal route by using thioacetamide (TAA) as both the sulfur source and reducing agent. The as-prepared CuS-GNS composites with an appropriate content of graphene exhibited an even higher peroxidase-like catalytic activity than pristine CuS nanoparticles in acetate buffer solution (pH = 4.0), which provided a facile method for the colorimetric detection of hydrogen peroxide (H2O2). It was calculated that H2O2 could be detected as low as 1.2 μM (S/N = 3) with a wide linear range from 2.0 to 20.0 μM (R(2) = 0.992), indicating that the as-prepared catalyst as an artificial peroxidase is promising for application in biosensors and environmental monitoring. PMID:23933916

  8. Integrated phospholipidomics and transcriptomics analysis of Saccharomyces cerevisiae with enhanced tolerance to a mixture of acetic acid, furfural, and phenol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A mixture of acetic acid, furfural and phenol (AFP), three representative lignocellulose derived inhibitors, significantly inhibited the growth and bioethanol production of Saccharomyces cerevisiae. In order to uncover mechanisms behind the enhanced tolerance of an inhibitor-tolerant S.cerevisiae s...

  9. Overexpression of Glutathione Synthetase in Indian Mustard Enhances Cadmium Accumulation and Tolerance1

    PubMed Central

    Liang Zhu, Yong; Pilon-Smits, Elizabeth A.H.; Jouanin, Lise; Terry, Norman

    1999-01-01

    An important pathway by which plants detoxify heavy metals is through sequestration with heavy-metal-binding peptides called phytochelatins or their precursor, glutathione. To identify limiting factors for heavy-metal accumulation and tolerance, and to develop transgenic plants with an increased capacity to accumulate and/or tolerate heavy metals, the Escherichia coli gshII gene encoding glutathione synthetase (GS) was overexpressed in the cytosol of Indian mustard (Brassica juncea). The transgenic GS plants accumulated significantly more Cd than the wild type: shoot Cd concentrations were up to 25% higher and total Cd accumulation per shoot was up to 3-fold higher. Moreover, the GS plants showed enhanced tolerance to Cd at both the seedling and mature-plant stages. Cd accumulation and tolerance were correlated with the gshII expression level. Cd-treated GS plants had higher concentrations of glutathione, phytochelatin, thiol, S, and Ca than wild-type plants. We conclude that in the presence of Cd, the GS enzyme is rate limiting for the biosynthesis of glutathione and phytochelatins, and that overexpression of GS offers a promising strategy for the production of plants with superior heavy-metal phytoremediation capacity. PMID:9880348

  10. Irradiation with low-dose gamma ray enhances tolerance to heat stress in Arabidopsis seedlings.

    PubMed

    Zhang, Liang; Zheng, Fengxia; Qi, Wencai; Wang, Tianqi; Ma, Lingyu; Qiu, Zongbo; Li, Jingyuan

    2016-06-01

    Gamma irradiation at low doses can stimulate the tolerance to environmental stress in plants. However, the knowledge regarding the mechanisms underlying the enhanced tolerance induced by low-dose gamma irradiation is far from fully understood. In this study, to investigate the physiological and molecular mechanisms of heat stress alleviated by low-dose gamma irradiation, the Arabidopsis seeds were exposed to a range of doses before subjected to heat treatment. Our results showed that 50-Gy gamma irradiation maximally promoted seedling growth in response to heat stress. The production rate of superoxide radical and contents of hydrogen peroxide and malondialdehyde in the seedlings irradiated with 50-Gy dose under heat stress were significantly lower than those of controls. The activities of antioxidant enzymes, glutathione (GSH) content and proline level in the gamma-irradiated seedlings were significantly increased compared with the controls. Furthermore, transcriptional expression analysis of selected genes revealed that some components related to heat tolerance were stimulated by low-dose gamma irradiation under heat shock. Our results suggest that low-dose gamma irradiation can modulate the physiological responses as well as gene expression related to heat tolerance, thus alleviating the stress damage in Arabidopsis seedlings. PMID:26945467

  11. A dehydrin gene isolated from feral olive enhances drought tolerance in Arabidopsis transgenic plants

    PubMed Central

    Chiappetta, Adriana; Muto, Antonella; Bruno, Leonardo; Woloszynska, Magdalena; Lijsebettens, Mieke Van; Bitonti, Maria B.

    2015-01-01

    Dehydrins belong to a protein family whose expression may be induced or enhanced by developmental process and environmental stresses that lead to cell dehydration. A dehydrin gene named OesDHN was isolated and characterized from oleaster (Olea europaea L. subsp. europaea, var. sylvestris), the wild form of olive. To elucidate the contribution of OesDHN in the development of drought tolerance, its expression levels were investigated in oleaster plants during development and under drought stress condition. The involvement of OesDHN in plant stress response was also evaluated in Arabidopsis transgenic lines, engineered to overexpress this gene, and exposed to a controlled mild osmotic stress. OesDHN expression was found to be modulated during development and induced under mild drought stress in oleaster plants. In addition, the Arabidopsis transgenic plants showed a better tolerance to osmotic stress than wild-type plants. The results demonstrated that OesDHN expression is induced by drought stress and is able to confer osmotic stress tolerance. We suggest a role for OesDHN, as a putative functional marker of plant stress tolerance. PMID:26175736

  12. Recyclable enzyme mimic of cubic Fe3O4 nanoparticles loaded on graphene oxide-dispersed carbon nanotubes with enhanced peroxidase-like catalysis and electrocatalysis

    SciTech Connect

    Wang, Hua; Li, Shuai; Si, Yanmei; Sun, Zhongzhao; Li, Shuying; Lin, Yuehe

    2014-01-01

    Fe3O4 nanoparticles as nanocatalysts may present peroxidase-like catalysis activities and high electrocatalysis if loaded on conductive carbon nanotube (CNT) supports; however, their catalysis performances in an aqueous system might still be challenged by the poor aqueous dispersion of hydrophobic carbon supports and/or low stability of loaded iron catalysts. In this work, amphiphilic graphene oxide nanosheets were employed as “surfactant” to disperse CNTs to create stable graphene oxide-dispersed CNT (GCNT) supports in water for covalently loading cubic Fe3O4 nanoparticles with improved distribution and binding efficiency. Compared with original Fe3O4 nanos and CNT-loaded Fe3O4 nanocomplex, the prepared GCNT–Fe3O4 nanocomposite could achieve higher aqueous stability and, especially, much stronger peroxidase-like catalysis and electrocatalysis to H2O2, presumably resulting from the synergetic effects of two conductive carbon supports and cubic Fe3O4 nanocatalysts effectively loaded. Colorimetric and direct electrochemical detections of H2O2 and glucose using the GCNT–Fe3O4 nanocomposite were conducted with high detection sensitivities, demonstrating the feasibility of practical sensing applications. Such a magnetically recyclable “enzyme mimic” may circumvent some disadvantages of natural protein enzymes and common inorganic catalysts, featuring the multi-functions of high peroxidase-like catalysis, strong electrocatalysis, magnetic separation/recyclability, environmental stability, and direct H2O2 electrochemistry.

  13. Novel Applications of Peroxidase

    NASA Astrophysics Data System (ADS)

    Rob, Abdul; Ball, Andrew S.; Tuncer, Munir; Wilson, Michael T.

    1997-02-01

    The article entitled "Novel Biocatalysts Will Work Even Better for Industry" published recently in this Journal (1) was informative and interesting. However it touched only briefly on the application of peroxidase as catalyst. Here, we would like to mention in more detail the novel applications of peroxidase in agricultural, paper pulp, water treatment, pharmaceutical, and medical situations. Firstly, the peroxidase isolated from Phanerochaete chyrosporium has been shown to detoxify herbicides such as atrazine to less toxic compounds and would certainly find potential application in agriculture (2). Secondly, the peroxidase produced by Streptomyces thermoviolaceus may find application in the paper pulp industry as a delignifying agent (3). Thirdly, it has been shown that extracellular peroxidase produced by Streptomyces avermitilis can remove the intense color from paper-mill effluent obtained after semichemical alkaline pulping of wheat straw (4), and thus this enzyme might find application as a catalyst in water treatment plants. Fourthly, the heme-containing horseradish peroxidase enzyme has been exploited in several diagnostic applications in pharmaceutics and medicine, such as the detection of human immunodeficiency virus and cystic fibrosis (5-10). Finally, recent work from our laboratory has suggested that thermophilic nonheme peroxidase produced by Thermomonospora fusca BD25 may find medical use in the diagnosis of myocardial infarction (11, 12). Literature Cited 1. Wiseman, A. J. Chem. Educ. 1996, 73, 55-58. 2. Mougin, C. Appl. Environ. Microbiol. 1994, 60, 705-708. 3. McCarthy A. J.; Peace, W.; Broda, P. Appl. Microbiol. Technol. 1985, 23, 238-244. 4. Hernandez, M; Rodriguez J; Soliveri, J; Copa, J. L; Perez, M. I; Arias, M. E. Appl. Environ. Microbiol. 1994, 60, 3909-3913. 5. Hopfer, S. M.; Aslanzadeh, J. Ann. Clin. Lab. Sci. 1995, 25, 475-480. 6. Suzuki, K; Iman, M. J. Virol. Methods 1995, 55, 347-356. 7. Nielsen, K. J. Immunoassay 1995, 16, 183-197. 8

  14. Enhancement of oxidative and drought tolerance in Arabidopsis by overaccumulation of antioxidant flavonoids

    PubMed Central

    Nakabayashi, Ryo; Yonekura-Sakakibara, Keiko; Urano, Kaoru; Suzuki, Makoto; Yamada, Yutaka; Nishizawa, Tomoko; Matsuda, Fumio; Kojima, Mikiko; Sakakibara, Hitoshi; Shinozaki, Kazuo; Michael, Anthony J; Tohge, Takayuki; Yamazaki, Mami; Saito, Kazuki

    2014-01-01

    The notion that plants use specialized metabolism to protect against environmental stresses needs to be experimentally proven by addressing the question of whether stress tolerance by specialized metabolism is directly due to metabolites such as flavonoids. We report that flavonoids with radical scavenging activity mitigate against oxidative and drought stress in Arabidopsis thaliana. Metabolome and transcriptome profiling and experiments with oxidative and drought stress in wild-type, single overexpressors of MYB12/PFG1 (PRODUCTION OF FLAVONOL GLYCOSIDES1) or MYB75/PAP1 (PRODUCTION OF ANTHOCYANIN PIGMENT1), double overexpressors of MYB12 and PAP1, transparent testa4 (tt4) as a flavonoid-deficient mutant, and flavonoid-deficient MYB12 or PAP1 overexpressing lines (obtained by crossing tt4 and the individual MYB overexpressor) demonstrated that flavonoid overaccumulation was key to enhanced tolerance to such stresses. Antioxidative activity assays using 2,2-diphenyl-1-picrylhydrazyl, methyl viologen, and 3,3′-diaminobenzidine clearly showed that anthocyanin overaccumulation with strong in vitro antioxidative activity mitigated the accumulation of reactive oxygen species in vivo under oxidative and drought stress. These data confirm the usefulness of flavonoids for enhancing both biotic and abiotic stress tolerance in crops. PMID:24274116

  15. Brassica oleracea MATE encodes a citrate transporter and enhances aluminum tolerance in Arabidopsis thaliana.

    PubMed

    Wu, Xinxin; Li, Ren; Shi, Jin; Wang, Jinfang; Sun, Qianqian; Zhang, Haijun; Xing, Yanxia; Qi, Yan; Zhang, Na; Guo, Yang-Dong

    2014-08-01

    The secretion of organic acid anions from roots is an important mechanism for plant aluminum (Al) tolerance. Here we report cloning and characterizing BoMATE (KF031944), a multidrug and toxic compound extrusion (MATE) family gene from cabbage (Brassica oleracea). The expression of BoMATE was more abundant in roots than in shoots, and it was highly induced by Al treatment. The (14)C-citrate efflux experiments in oocytes demonstrated that BoMATE is a citrate transporter. Electrophysiological analysis and SIET analysis of Xenopus oocytes expressing BoMATE indicated BoMATE is activated by Al. Transient expression of BoMATE in onion epidermal cells demonstrated that it localized to the plasma membrane. Compared with the wild-type Arabidopsis, the transgenic lines constitutively overexpressing BoMATE enhanced Al tolerance and increased citrate secretion. In addition, Arabidopsis transgenic lines had a lower K(+) efflux and higher H(+) efflux, in the presence of Al, than control wild type in the distal elongation zone (DEZ). This is the first direct evidence that MATE protein is involved in the K(+) and H(+) flux in response to Al treatment. Taken together, our results show that BoMATE is an Al-induced citrate transporter and enhances aluminum tolerance in Arabidopsis thaliana. PMID:24850836

  16. Enhanced development of dispositional tolerance to methadone by desipramine given together with methadone

    SciTech Connect

    Liu, S.J.; Wang, R.I.H.

    1985-02-25

    Rats given 2-day oral administration of methadone (15 mg/kg, twice on day 1 and once on day 2) by gastric tube developed dispositional tolerance to methadone analgesia as demonstrated by a decrease in analgesic response and by an increase in methadone metabolism. The increased metabolism of methadone was evidenced by a decrease in brain concentration of /sup 14/C-methadone and increases in the percentages of total /sup 14/C in liver or urine as /sup 14/C-water-soluble metabolites (/sup 14/C-WSM) after the rats were challenged with a test dose of /sup 14/C-methadone. Two-day pretreatment with a combination of desipramine (DMI) (10 mg/kg, ip) and methadone (15 mg/kg, po) enhanced the development of dispositional tolerance to methadone analgesia which was evidenced by a greater decrease in the brain concentration of methadone and a greater increase in methadone metabolism as compared to those changes in rats pretreated with only methadone. Repeated treatment with DMI alone neither decreased the analgesic effect of methadone nor stimulated methadone metabolism. It is suggested that DMI given together with methadone promoted the induction of methadone metabolism in the liver by prolonging the enzyme-stimulating state of methadone, thus enhancing the development of dispositional tolerance to methadone. 20 references, 1 figure, 1 table.

  17. Trehalose enhances osmotic tolerance and suppresses lysophosphatidylcholine-induced acrosome reaction in ram spermatozoon.

    PubMed

    Ahmad, E; Naseer, Z; Aksoy, M; Küçük, N; Uçan, U; Serin, I; Ceylan, A

    2015-09-01

    This study was aimed to investigate the influence of trehalose on osmotic tolerance and the ability of ram spermatozoon to undergo acrosome reaction induced by lysophosphatidylcholine (LPC). In experiment 1, the diluted ejaculates were exposed to anisosmotic fructose solutions (70, 500, 750 and 1000 mOsm l(-1) ) with or without 50 mm trehalose. The presence of trehalose in hyperosmotic conditions enhanced (P < 0.05) the percentage of live, live-intact and intact spermatozoa. Similarly, trehalose enhanced (P < 0.05) the live and live-intact spermatozoa during hypo-osmotic conditions. In experiment 2, the centrifuged ejaculates were diluted with TCG only or TCG containing either 50 or 100 mm trehalose. The acrosome reaction was induced by LPC. The percentage of acrosome-reacted spermatozoon was less (P < 0.05) in trehalose-supplemented groups compared to control. In experiment 3, the ejaculates were cryopreserved in an extender containing 0 mm (control), 50 mm or 100 mm trehalose. Supplementation of extender with trehalose, either 50 mm or 100 mm, enhanced the cryosurvival rate (P < 0.05) compared to the control. In conclusion, the presence of trehalose in anisosmotic conditions enhances the osmotic tolerance, cryosurvival rate of ram spermatozoon and suppresses their ability to undergo LPC and cryo-induced acrosome reaction. PMID:25269572

  18. Enhanced radiation tolerance in nitride multilayered nanofilms with small period-thicknesses

    SciTech Connect

    Hong Mengqing; Ren Feng; Zhang Hongxiu; Xiao Xiangheng; Tian Canxin; Fu Dejun; Jiang Changzhong; Yang Bing; Wang Yongqiang

    2012-10-08

    This paper demonstrates a substantial enhancement in radiation tolerance for small period-thickness of CrN/AlTiN multilayered nanofilms. CrN/AlTiN multilayered nanofilms with period-thicknesses of 3, 5, 7, and 9 nm were irradiated by 190 keV Ar{sup +} ions to fluences ranging from 1 to 5 Multiplication-Sign 10{sup 16} ions/cm{sup 2}. Nanofilm with 3 nm period-thickness begins to be amorphized under 5 Multiplication-Sign 10{sup 16} ions/cm{sup 2}, while those with larger period-thicknesses are amorphized under 3 Multiplication-Sign 10{sup 16} ions/cm{sup 2}. Our results show that multilayered ceramic nanofilms are potential radiation tolerant materials with good properties. The interfaces in the multilayered nanofilms act as good sinks to absorb the radiation-induced defects.

  19. Plant Growth-Promoting Rhizobacteria Enhance Salinity Stress Tolerance in Okra through ROS-Scavenging Enzymes.

    PubMed

    Habib, Sheikh Hasna; Kausar, Hossain; Saud, Halimi Mohd

    2016-01-01

    Salinity is a major environmental stress that limits crop production worldwide. In this study, we characterized plant growth-promoting rhizobacteria (PGPR) containing 1-aminocyclopropane-1-carboxylate (ACC) deaminase and examined their effect on salinity stress tolerance in okra through the induction of ROS-scavenging enzyme activity. PGPR inoculated okra plants exhibited higher germination percentage, growth parameters, and chlorophyll content than control plants. Increased antioxidant enzyme activities (SOD, APX, and CAT) and upregulation of ROS pathway genes (CAT, APX, GR, and DHAR) were observed in PGPR inoculated okra plants under salinity stress. With some exceptions, inoculation with Enterobacter sp. UPMR18 had a significant influence on all tested parameters under salt stress, as compared to other treatments. Thus, the ACC deaminase-containing PGPR isolate Enterobacter sp. UPMR18 could be an effective bioresource for enhancing salt tolerance and growth of okra plants under salinity stress. PMID:26951880

  20. Plant Growth-Promoting Rhizobacteria Enhance Salinity Stress Tolerance in Okra through ROS-Scavenging Enzymes

    PubMed Central

    Habib, Sheikh Hasna; Kausar, Hossain; Saud, Halimi Mohd

    2016-01-01

    Salinity is a major environmental stress that limits crop production worldwide. In this study, we characterized plant growth-promoting rhizobacteria (PGPR) containing 1-aminocyclopropane-1-carboxylate (ACC) deaminase and examined their effect on salinity stress tolerance in okra through the induction of ROS-scavenging enzyme activity. PGPR inoculated okra plants exhibited higher germination percentage, growth parameters, and chlorophyll content than control plants. Increased antioxidant enzyme activities (SOD, APX, and CAT) and upregulation of ROS pathway genes (CAT, APX, GR, and DHAR) were observed in PGPR inoculated okra plants under salinity stress. With some exceptions, inoculation with Enterobacter sp. UPMR18 had a significant influence on all tested parameters under salt stress, as compared to other treatments. Thus, the ACC deaminase-containing PGPR isolate Enterobacter sp. UPMR18 could be an effective bioresource for enhancing salt tolerance and growth of okra plants under salinity stress. PMID:26951880

  1. Potential utilization of NAC transcription factors to enhance abiotic stress tolerance in plants by biotechnological approach.

    PubMed

    Tran, Lam-Son Phan; Nishiyama, Rie; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo

    2010-01-01

    Abiotic stresses such as extreme temperature, drought, high salinity, cold and waterlogging often result in significant losses to the yields of economically important crops. Plants constantly exposed to capricious conditions have adapted at the molecular, cellular, physiological and biochemical level, enabling them to survive and cope with adverse environmental stresses. NAC (NAM, ATAF and CUC) transcription factors (TFs), which constitute one of the largest families of plant-specific TFs, have been reported to enhance tolerance against various stresses, such as drought, high salinity and cold, in a number of plants. In this review the NAC TF family will be described and the potential use of NAC TFs in development of improved stress tolerant transgenic crops will be discussed. PMID:21912210

  2. Arabidopsis Enhanced Drought Tolerance1/HOMEODOMAIN GLABROUS11 Confers Drought Tolerance in Transgenic Rice without Yield Penalty1[W][OA

    PubMed Central

    Yu, Linhui; Chen, Xi; Wang, Zhen; Wang, Shimei; Wang, Yuping; Zhu, Qisheng; Li, Shigui; Xiang, Chengbin

    2013-01-01

    Enhancing drought tolerance without yield decrease has been a great challenge in crop improvement. Here, we report the Arabidopsis (Arabidopsis thaliana) homodomain-leucine zipper transcription factor Enhanced Drought Tolerance/HOMEODOMAIN GLABROUS11 (EDT1/HDG11) was able to confer drought tolerance and increase grain yield in transgenic rice (Oryza sativa) plants. The improved drought tolerance was associated with a more extensive root system, reduced stomatal density, and higher water use efficiency. The transgenic rice plants also had higher levels of abscisic acid, proline, soluble sugar, and reactive oxygen species-scavenging enzyme activities during stress treatments. The increased grain yield of the transgenic rice was contributed by improved seed setting, larger panicle, and more tillers as well as increased photosynthetic capacity. Digital gene expression analysis indicated that AtEDT1/HDG11 had a significant influence on gene expression profile in rice, which was consistent with the observed phenotypes of transgenic rice plants. Our study shows that AtEDT1/HDG11 can improve both stress tolerance and grain yield in rice, demonstrating the efficacy of AtEDT1/HDG11 in crop improvement. PMID:23735506

  3. Overexpression of malate dehydrogenase in transgenic alfalfa enhances organic acid synthesis and confers tolerance to aluminum.

    PubMed

    Tesfaye, M; Temple, S J; Allan, D L; Vance, C P; Samac, D A

    2001-12-01

    Al toxicity is a severe impediment to production of many crops in acid soil. Toxicity can be reduced through lime application to raise soil pH, however this amendment does not remedy subsoil acidity, and liming may not always be practical or cost-effective. Addition of organic acids to plant nutrient solutions alleviates phytotoxic Al effects, presumably by chelating Al and rendering it less toxic. In an effort to increase organic acid secretion and thereby enhance Al tolerance in alfalfa (Medicago sativa), we produced transgenic plants using nodule-enhanced forms of malate dehydrogenase and phosphoenolpyruvate carboxylase cDNAs under the control of the constitutive cauliflower mosaic virus 35S promoter. We report that a 1.6-fold increase in malate dehydrogenase enzyme specific activity in root tips of selected transgenic alfalfa led to a 4.2-fold increase in root concentration as well as a 7.1-fold increase in root exudation of citrate, oxalate, malate, succinate, and acetate compared with untransformed control alfalfa plants. Overexpression of phosphoenolpyruvate carboxylase enzyme specific activity in transgenic alfalfa did not result in increased root exudation of organic acids. The degree of Al tolerance by transformed plants in hydroponic solutions and in naturally acid soil corresponded with their patterns of organic acid exudation and supports the concept that enhancing organic acid synthesis in plants may be an effective strategy to cope with soil acidity and Al toxicity. PMID:11743127

  4. Expression of Vitis amurensis NAC26 in Arabidopsis enhances drought tolerance by modulating jasmonic acid synthesis

    PubMed Central

    Fang, Linchuan; Su, Lingye; Sun, Xiaoming; Li, Xinbo; Sun, Mengxiang; Karungo, Sospeter Karanja; Fang, Shuang; Chu, Jinfang; Li, Shaohua; Xin, Haiping

    2016-01-01

    The growth and fruit quality of grapevines are widely affected by abnormal climatic conditions such as water deficits, but many of the precise mechanisms by which grapevines respond to drought stress are still largely unknown. Here, we report that VaNAC26, a member of the NAC transcription factor family, was upregulated dramatically during cold, drought and salinity treatments in Vitis amurensis, a cold and drought-hardy wild Vitis species. Heterologous overexpression of VaNAC26 enhanced drought and salt tolerance in transgenic Arabidopsis. Higher activities of antioxidant enzymes and lower concentrations of H2O2 and O2 − were found in VaNAC26-OE lines than in wild type plants under drought stress. These results indicated that scavenging by reactive oxygen species (ROS) was enhanced by VaNAC26 in transgenic lines. Microarray-based transcriptome analysis revealed that genes related to jasmonic acid (JA) synthesis and signaling were upregulated in VaNAC26-OE lines under both normal and drought conditions. VaNAC26 showed a specific binding ability on the NAC recognition sequence (NACRS) motif, which broadly exists in the promoter regions of upregulated genes in transgenic lines. Endogenous JA content significantly increased in the VaNAC26-OE lines 2 and 3. Our data suggest that VaNAC26 responds to abiotic stresses and may enhance drought tolerance by transcriptional regulation of JA synthesis in Arabidopsis. PMID:27162276

  5. Expression of Vitis amurensis NAC26 in Arabidopsis enhances drought tolerance by modulating jasmonic acid synthesis.

    PubMed

    Fang, Linchuan; Su, Lingye; Sun, Xiaoming; Li, Xinbo; Sun, Mengxiang; Karungo, Sospeter Karanja; Fang, Shuang; Chu, Jinfang; Li, Shaohua; Xin, Haiping

    2016-04-01

    The growth and fruit quality of grapevines are widely affected by abnormal climatic conditions such as water deficits, but many of the precise mechanisms by which grapevines respond to drought stress are still largely unknown. Here, we report that VaNAC26, a member of the NAC transcription factor family, was upregulated dramatically during cold, drought and salinity treatments in Vitis amurensis, a cold and drought-hardy wild Vitis species. Heterologous overexpression of VaNAC26 enhanced drought and salt tolerance in transgenic Arabidopsis. Higher activities of antioxidant enzymes and lower concentrations of H2O2 and O2 (-) were found in VaNAC26-OE lines than in wild type plants under drought stress. These results indicated that scavenging by reactive oxygen species (ROS) was enhanced by VaNAC26 in transgenic lines. Microarray-based transcriptome analysis revealed that genes related to jasmonic acid (JA) synthesis and signaling were upregulated in VaNAC26-OE lines under both normal and drought conditions. VaNAC26 showed a specific binding ability on the NAC recognition sequence (NACRS) motif, which broadly exists in the promoter regions of upregulated genes in transgenic lines. Endogenous JA content significantly increased in the VaNAC26-OE lines 2 and 3. Our data suggest that VaNAC26 responds to abiotic stresses and may enhance drought tolerance by transcriptional regulation of JA synthesis in Arabidopsis. PMID:27162276

  6. Enhanced selenium tolerance and accumulation in transgenic Arabidopsis expressing a mouse selenocysteine lyase.

    PubMed

    Pilon, Marinus; Owen, Jennifer D; Garifullina, Gulnara F; Kurihara, Tatsuo; Mihara, Hisaaki; Esaki, Nobuyoshi; Pilon-Smits, Elizabeth A H

    2003-03-01

    Selenium (Se) toxicity is thought to be due to nonspecific incorporation of selenocysteine (Se-Cys) into proteins, replacing Cys. In an attempt to direct Se flow away from incorporation into proteins, a mouse (Mus musculus) Se-Cys lyase (SL) was expressed in the cytosol or chloroplasts of Arabidopsis. This enzyme specifically catalyzes the decomposition of Se-Cys into elemental Se and alanine. The resulting SL transgenics were shown to express the mouse enzyme in the expected intracellular location, and to have SL activities up to 2-fold (cytosolic lines) or 6-fold (chloroplastic lines) higher than wild-type plants. Se incorporation into proteins was reduced 2-fold in both types of SL transgenics, indicating that the approach successfully redirected Se flow in the plant. Both the cytosolic and chloroplastic SL plants showed enhanced shoot Se concentrations, up to 1.5-fold compared with wild type. The cytosolic SL plants showed enhanced tolerance to Se, presumably because of their reduced protein Se levels. Surprisingly, the chloroplastic SL transgenics were less tolerant to Se, indicating that (over) production of elemental Se in the chloroplast is toxic. Expression of SL in the cytosol may be a useful approach for the creation of plants with enhanced Se phytoremediation capacity. PMID:12644675

  7. Transcriptional up-regulation of the mouse cytosolic glutathione peroxidase gene in erythroid cells is due to a tissue-specific 3' enhancer containing functionally important CACC/GT motifs and binding sites for GATA and Ets transcription factors.

    PubMed Central

    O'Prey, J; Ramsay, S; Chambers, I; Harrison, P R

    1993-01-01

    Nuclear run-on experiments have shown that the high level of expression of the mouse cytosolic glutathione peroxidase mRNA in erythroid cells is due to up-regulation of the gene at the transcriptional level. Studies of the chromatin structure around the cytosolic glutathione peroxidase gene have revealed a series of DNase I hypersensitive sites (DHSS) in the 3' flanking region of the gene in erythroid and other high-expression tissues that are lacking in low-expression cells, in addition to a DHSS over the promoter region in both high- and low-expression tissues. Functional transfection experiments have demonstrated that one of the 3' DHSS regions functions as an enhancer in erythroid cells but not in a low-expression epithelial cell line; and site-directed mutagenesis and footprinting experiments reveal that the activity of the erythroid cell-specific enhancer requires a cluster of binding sites for the CACC/GT box factors and the GATA and Ets families of transcription factors. Images PMID:8413228

  8. A Wheat Allene Oxide Cyclase Gene Enhances Salinity Tolerance via Jasmonate Signaling1[C][W

    PubMed Central

    Zhao, Yang; Dong, Wei; Zhang, Naibo; Ai, Xinghui; Wang, Mengcheng; Huang, Zhigang; Xiao, Langtao; Xia, Guangmin

    2014-01-01

    One of the two branches of the α-linolenic acid metabolism pathway is catalyzed by 12-oxo-phytodienoic acid reductase I, and the other is involved in jasmonic acid (JA) synthesis. The former is known to be active in the response to salinity tolerance in wheat (Triticum aestivum), but the participation of the latter in this response has not been established as yet. Here, the salinity-responsive bread wheat gene TaAOC1, which encodes an allene oxide cyclase involved in the α-linolenic acid metabolism pathway, was constitutively expressed in both bread wheat and Arabidopsis (Arabidopsis thaliana). In both species, transgenic lines exhibited an enhanced level of tolerance to salinity. The transgenic plants accumulated a higher content of JA and developed shorter roots. Both the shortened roots and the salinity tolerance were abolished in a background lacking a functional AtMYC2, a key component of the JA and abscisic acid signaling pathway, but were still expressed in a background deficient with respect to abscisic acid synthesis. We provide the first evidence, to our knowledge, suggesting that JA is also involved in the plant salinity response and that the α-linolenic acid metabolism pathway has a regulatory role over this response. PMID:24326670

  9. A Cu/Zn superoxide dismutase from Jatropha curcas enhances salt tolerance of Arabidopsis thaliana.

    PubMed

    Liu, Z B; Zhang, W J; Gong, X D; Zhang, Q; Zhou, L R

    2015-01-01

    Superoxide dismutases (SODs) are involved in protecting plants against diverse biotic and abiotic stresses. In the present study, a novel Cu/Zn-SOD gene (JcCu/Zn-SOD) was cloned from Jatropha curcas L. Quantitative reverse transcription-polymerase chain reaction analysis revealed that JcCu/Zn-SOD is constitutively expressed in different tissues of J. curcas and induced under NaCl treatment. To characterize the function of this gene with respect to salt tolerance, the construct p35S:JcCu/Zn-SOD was developed and transformed into Arabidopsis using Agrobacterium-mediated transformation. Compared with wild-type, transgenic plants over-expressing JcCu/Zn-SOD showed enhanced tolerance to salt stress during germination, seedling establishment, and growth in terms of longer root, larger rosette area, and a larger number of leaves in addition to higher SOD activity levels under NaCl stress. In addition, over-expression of JcCu/Zn-SOD resulted in lower monodialdehyde content in transgenic Arabidopsis compared to wild-type plants under the same NaCl stress. Therefore, JcCu/Zn-SOD can increase a plant salt stress tolerance potentially by reducing oxidant injury. PMID:25867355

  10. Ectomycorrhizas with Paxillus involutus enhance cadmium uptake and tolerance in Populus × canescens.

    PubMed

    Ma, Yonglu; He, Jiali; Ma, Chaofeng; Luo, Jie; Li, Hong; Liu, Tongxian; Polle, Andrea; Peng, Changhui; Luo, Zhi-Bin

    2014-03-01

    Ectomycorrhizas (EMs), which are symbiotic organs formed between tree roots and certain fungi, can mediate cadmium (Cd) tolerance of host plants, but the underlying physiological and molecular mechanisms are not fully understood. To investigate EMs mediated Cd tolerance in woody plants, Populus × canescens was inoculated with Paxillus involutus (strain MAJ) to establish mycorrhizal roots. Mycorrhizal poplars and non-mycorrhizal controls were exposed to 0 or 50 μM CdSO4 . EMs displayed higher net Cd(2+) influx than non-mycorrhizal roots. Net Cd(2+) influx was coupled with net H(+) efflux and inactivation of plasma membrane (PM) H(+) -ATPases reduced Cd(2+) uptake of EMs less than of non-mycorrhizal roots. Consistent with higher Cd(2+) uptake in EMs, in most cases, transcript levels of genes involved in Cd(2+) uptake, transport and detoxification processes were increased in EMs compared to non-mycorrhizal roots. Higher CO2 assimilation, improved nutrient and carbohydrate status, and alleviated oxidative stress were found in mycorrhizal compared to non-mycorrhizal poplars despite higher Cd(2+) accumulation. These results indicate that mycorrhizas increase Cd(2+) uptake, probably by an enlarged root volume and overexpression of genes involved in Cd(2+) uptake and transport, and concurrently enhance Po. × canescens Cd tolerance by increased detoxification, improved nutrient and carbohydrate status and defence preparedness. PMID:23937227

  11. Enhanced water stress tolerance of transgenic maize plants over-expressing LEA Rab28 gene.

    PubMed

    Amara, Imen; Capellades, Montserrat; Ludevid, M Dolors; Pagès, Montserrat; Goday, Adela

    2013-06-15

    Late Embryogenesis Abundant (LEA) proteins participate in plant stress responses and contribute to the acquisition of desiccation tolerance. In this report Rab28 LEA gene has been over-expressed in maize plants under a constitutive maize promoter. The expression of Rab28 transcripts led to the accumulation and stability of Rab28 protein in the transgenic plants. Native Rab28 protein is localized to nucleoli in wild type maize embryo cells; here we find by whole-mount immunocytochemistry that in root cells of Rab28 transgenic and wild-type plants the protein is also associated to nucleolar structures. Transgenic plants were tested for stress tolerance and resulted in sustained growth under polyethyleneglycol (PEG)-mediated dehydration compared to wild-type controls. Under osmotic stress transgenic seedlings showed increased leaf and root areas, higher relative water content (RWC), reduced chlorophyll loss and lower Malondialdehyde (MDA) production in relation to wild-type plants. Moreover, transgenic seeds exhibited higher germination rates than wild-type seeds under water deficit. Overall, our results highlight the presence of transgenic Rab28 protein in nucleolar structures and point to the potential of group 5 LEA Rab28 gene as candidate to enhance stress tolerance in maize plants. PMID:23384757

  12. Modulation of cadmium bioaccumulation and enhancing cadmium tolerance in Pichia kudriavzevii by sodium chloride preincubation.

    PubMed

    Ma, Ning; Li, Chunsheng; Zhang, Dandan; Yu, Jinzhi; Xu, Ying

    2016-07-01

    Application of growing microorganisms for cadmium removal is limited by the sensitivity of living cells to cadmium. The effects of sodium chloride (NaCl) preincubation on the cadmium bioaccumulation and tolerance of Pichia kudriavzevii and Saccharomyces cerevisiae were investigated in this study. NaCl preincubation significantly reduced the intracellular and cell-surface cadmium bioaccumulation of P. kudriavzevii at both 6 and 20 mg L(-1) cadmium, while no obvious effect was observed in S. cerevisiae except that the intracellular cadmium bioaccumulation at 20 mg L(-1) cadmium was reduced obviously by 20-60 g L(-1)  NaCl. For both yeasts, the improved contents of protein and proline after NaCl preincubation contributed to the cadmium tolerance. The thiol contents in P. kudriavzevii under cadmium stress were alleviated by NaCl preincubation, which might be due to the decrease of intracellular cadmium bioaccumulation. NaCl preincubation enhanced the contents of glycerol and trehalose in P. kudriavzevii under cadmium stress, while no acceleration was observed in S. cerevisiae. The results suggested that NaCl preincubation could be applied in cadmium removal by growing P. kudriavzevii to increase the cadmium tolerance of the yeast. PMID:26753521

  13. Transgenic poplar expressing codA exhibits enhanced growth and abiotic stress tolerance.

    PubMed

    Ke, Qingbo; Wang, Zhi; Ji, Chang Yoon; Jeong, Jae Cheol; Lee, Haeng-Soon; Li, Hongbing; Xu, Bingcheng; Deng, Xiping; Kwak, Sang-Soo

    2016-03-01

    Glycine betaine (GB), a compatible solute, effectively stabilizes the structure and function of macromolecules and enhances abiotic stress tolerance in plants. We generated transgenic poplar plants (Populus alba × Populus glandulosa) expressing a bacterial choline oxidase (codA) gene under the control of the oxidative stress-inducible SWPA2 promoter (referred to as SC plants). Among the 13 SC plants generated, three lines (SC4, SC14 and SC21) were established based on codA transcript levels, tolerance to methyl viologen-mediated oxidative stress and Southern blot analysis. Growth was better in SC plants than in non-transgenic (NT) plants, which was related to elevated transcript levels of auxin-response genes. SC plants accumulated higher levels of GB under oxidative stress compared to the NT plants. In addition, SC plants exhibited increased tolerance to drought and salt stress, which was associated with increased efficiency of photosystem II activity. Finally, SC plants maintained lower levels of ion leakage and reactive oxygen species under cold stress compared to the NT plants. These observations suggest that SC plants might be useful for reforestation on global marginal lands, including desertification and reclaimed areas. PMID:26795732

  14. Over-expression of Topoisomerase II Enhances Salt Stress Tolerance in Tobacco

    PubMed Central

    John, Riffat; Ganeshan, Uma; Singh, Badri N.; Kaul, Tanushri; Reddy, Malireddy K.; Sopory, Sudhir K.; Rajam, Manchikatla V.

    2016-01-01

    Topoisomerases are unique enzymes having an ability to remove or add DNA supercoils and untangle the snarled DNA. They can cut, shuffle, and religate DNA strands and remove the torsional stress during DNA replication, transcription or recombination events. In the present study, we over-expressed topoisomerase II (TopoII) in tobacco (Nicotiana tabaccum) and examined its role in growth and development as well as salt (NaCl) stress tolerance. Several putative transgenic plants were generated and the transgene integration and expression was confirmed by PCR and Southern blot analyses, and RT-PCR analysis respectively. Percent seed germination, shoot growth, and chlorophyll content revealed that transgenic lines over-expressing the NtTopoIIα-1 gene exhibited enhanced tolerance to salt (150 and 200 mM NaCl) stress. Moreover, over-expression of TopoII lead to the elevation in proline and glycine betaine levels in response to both concentrations of NaCl as compared to wild-type. In response to NaCl stress, TopoII over-expressing lines showed reduced lipid peroxidation derived malondialdehyde (MDA) generation. These results suggest that TopoII plays a pivotal role in salt stress tolerance in plants.

  15. The soybean GmbZIP1 transcription factor enhances multiple abiotic stress tolerances in transgenic plants.

    PubMed

    Gao, Shi-Qing; Chen, Ming; Xu, Zhao-Shi; Zhao, Chang-Ping; Li, Liancheng; Xu, Hui-jun; Tang, Yi-miao; Zhao, Xin; Ma, You-Zhi

    2011-04-01

    Abscisic acid (ABA)-responsive element binding proteins (AREBs) are basic domain/leucine zipper transcription factors that bind to the ABA-responsive element (ABRE) in the promoter regions of ABA-inducible genes in plants. A novel bZIP transcription factor gene, GmbZIP1, encoding 438 amino acids with a conserved bZIP domain composed of 60 amino acids was isolated from salt-tolerant soybean cv. Tiefeng 8. Southern blotting showed that only one copy was present in the soybean genome. Phylogenetic analyses showed that GmbZIP1 belonged to the AREB subfamily of the bZIP family and was most closely related to AtABF2 and OsTRAB1. The expression of GmbZIP1 was highly induced by ABA, drought, high salt and low temperature; and GmbZIP1 was expressed in soybean roots, stems and leaves under different stress conditions. GmbZIP1 was localized inside the nuclei of transformed onion epidermal cells. Overexpression of GmbZIP1 enhanced the responses of transgenic plants to ABA and triggered stomatal closure under stresses, potentially leading to improved tolerances to several abiotic stresses such as high salt, low temperature and drought in transgenic plants. Furthermore, overexpression of GmbZIP1 affected the expression of some ABA or stress-related genes involved in regulating stomatal closure in Arabidopsis under ABA, drought and high salt stress conditions. A few AREB elements were detected in the promoter region of those ABA or stress-related genes, suggesting that GmbZIP1 regulates the ABA response or stomatal closure mediated by those downstream genes in transgenic Arabidopsis. Moreover, GmbZIP1 was used to improve the drought tolerance trait of Chinese wheat varieties BS93. Functional analysis showed that overexpression of GmbZIP1 enhanced the drought tolerance of transgenic wheat, and transcripts of GmbZIP1 were detected in transgenic wheat using RT-PCR. In addition, GmbZIP1 overexpression did not result in growth retardation in all transgenic plants, suggesting that Gmb

  16. Modulation of cadmium toxicity and enhancing cadmium-tolerance in wheat seedlings by exogenous application of polyamines.

    PubMed

    Rady, Mostafa M; Hemida, Khaulood A

    2015-09-01

    Cadmium (Cd) stress causes several negative physiological, biochemical and structural changes due to the oxidative stress caused through the generation of ROS, leading to a reduction in plant growth. To look for an effective method to increase Cd tolerance of wheat seedlings, the effect of presoaking Triticum aestivum L. seeds in spermidine (Spd; 2mM) or spermine (Spm; 2mM) on seedling growth, physiological attributes and antioxidant defence system under 1mM Cd stress were investigated. Spm or Spd alleviated the adverse effects of Cd stress to convergent degrees. Presoaking wheat seeds in either polyamine increased the seedling growth and the activities of antioxidant enzymes compared to the control, but other attributes were slightly affected. Under Cd stress, presoaking seeds in either polyamine significantly increased seedling growth, membrane stability index, relative water content, concentrations of protein, starch, ascorbic acid, total glutathione, Spm and Spd, and the activities of superoxide dismutase and catalase. In contrast, electrolyte leakage, concentrations of proline, total soluble sugars, malondialdehyde, hydrogen peroxide and Cd(2+), and the activities of peroxidase and ascorbate peroxidase were reduced compared to the control. These results are important as the potential of Spd or Spm to alleviate the harmful effects of Cd stress offer an opportunity to increase the resistance of wheat seedlings to growth under Cd stress conditions. PMID:26004358

  17. GmCLC1 Confers Enhanced Salt Tolerance through Regulating Chloride Accumulation in Soybean

    PubMed Central

    Wei, Peipei; Wang, Longchao; Liu, Ailin; Yu, Bingjun; Lam, Hon-Ming

    2016-01-01

    The family of chloride channel proteins that mediate Cl- transportation play vital roles in plant nutrient supply, cellular action potential and turgor pressure adjustment, stomatal movement, hormone signal recognition and transduction, Cl- homeostasis, and abiotic and biotic stress tolerance. The anionic toxicity, mainly caused by chloride ions (Cl-), on plants under salt stress remains poorly understood. In this work, we investigated the function of soybean Cl-/H+ antiporter GmCLC1 under salt stress in transgenic Arabidopsis thaliana, soybean, and yeast. We found that GmCLC1 enhanced salt tolerance in transgenic A. thaliana by reducing the Cl- accumulation in shoots and hence released the negative impact of salt stress on plant growth. Overexpression of GmCLC1 in the hairy roots of soybean sequestered more Cl- in their roots and transferred less Cl- to their shoots, leading to lower relative electrolyte leakage values in the roots and leaves. When either the soybean GmCLC1 or the yeast chloride transporter gene, GEF1, was transformed into the yeast gef1 mutant, and then treated with different chloride salts (MnCl2, KCl, NaCl), enhanced survival rate was observed. The result indicates that GmCLC1 and GEF1 exerted similar effects on alleviating the stress of diverse chloride salts on the yeast gef1 mutant. Together, this work suggests a protective function of GmCLC1 under Cl- stress. PMID:27504114

  18. OST1 kinase modulates freezing tolerance by enhancing ICE1 stability in Arabidopsis.

    PubMed

    Ding, Yanglin; Li, Hui; Zhang, Xiaoyan; Xie, Qi; Gong, Zhizhong; Yang, Shuhua

    2015-02-01

    Cold stress is a major environmental factor that limits plant growth and development. The C-repeat-binding factor (CBF)-dependent cold signaling pathway is extensively studied in Arabidopsis; however, the specific protein kinases involved in this pathway remain elusive. Here we report that OST1 (open stomata 1), a well-known Ser/Thr protein kinase in ABA signaling, acts upstream of CBFs to positively regulate freezing tolerance. The ost1 mutants show freezing hypersensitivity, whereas transgenic plants overexpressing OST1 exhibit enhanced freezing tolerance. The OST1 kinase is activated by cold stress. Moreover, OST1 interacts with both the transcription factor ICE1 and the E3 ligase HOS1 in the CBF pathway. Cold-activated OST1 phosphorylates ICE1 and enhances its stability and transcriptional activity. Meanwhile, OST1 interferes with the interaction between HOS1 and ICE1, thus suppressing HOS1-mediated ICE1 degradation under cold stress. Our results thus uncover the unexpected roles of OST1 in modulating CBF-dependent cold signaling in Arabidopsis. PMID:25669882

  19. GmCLC1 Confers Enhanced Salt Tolerance through Regulating Chloride Accumulation in Soybean.

    PubMed

    Wei, Peipei; Wang, Longchao; Liu, Ailin; Yu, Bingjun; Lam, Hon-Ming

    2016-01-01

    The family of chloride channel proteins that mediate Cl(-) transportation play vital roles in plant nutrient supply, cellular action potential and turgor pressure adjustment, stomatal movement, hormone signal recognition and transduction, Cl(-) homeostasis, and abiotic and biotic stress tolerance. The anionic toxicity, mainly caused by chloride ions (Cl(-)), on plants under salt stress remains poorly understood. In this work, we investigated the function of soybean Cl(-)/H(+) antiporter GmCLC1 under salt stress in transgenic Arabidopsis thaliana, soybean, and yeast. We found that GmCLC1 enhanced salt tolerance in transgenic A. thaliana by reducing the Cl(-) accumulation in shoots and hence released the negative impact of salt stress on plant growth. Overexpression of GmCLC1 in the hairy roots of soybean sequestered more Cl(-) in their roots and transferred less Cl(-) to their shoots, leading to lower relative electrolyte leakage values in the roots and leaves. When either the soybean GmCLC1 or the yeast chloride transporter gene, GEF1, was transformed into the yeast gef1 mutant, and then treated with different chloride salts (MnCl2, KCl, NaCl), enhanced survival rate was observed. The result indicates that GmCLC1 and GEF1 exerted similar effects on alleviating the stress of diverse chloride salts on the yeast gef1 mutant. Together, this work suggests a protective function of GmCLC1 under Cl(-) stress. PMID:27504114

  20. Overexpression of Late Embryogenesis Abundant 14 enhances Arabidopsis salt stress tolerance

    SciTech Connect

    Jia, Fengjuan Qi, Shengdong Li, Hui Liu, Pu Li, Pengcheng Wu, Changai Zheng, Chengchao Huang, Jinguang

    2014-11-28

    Highlights: • It is the first time to investigate the biological function of AtLEA14 in salt stress response. • AtLEA14 enhances the salt stress tolerance both in Arabidopsis and yeast. • AtLEA14 responses to salt stress by stabilizing AtPP2-B11, an E3 ligase, under normal or salt stress conditions. - Abstract: Late embryogenesis abundant (LEA) proteins are implicated in various abiotic stresses in higher plants. In this study, we identified a LEA protein from Arabidopsis thaliana, AtLEA14, which was ubiquitously expressed in different tissues and remarkably induced with increased duration of salt treatment. Subcellular distribution analysis demonstrated that AtLEA14 was mainly localized in the cytoplasm. Transgenic Arabidopsis and yeast overexpressing AtLEA14 all exhibited enhanced tolerance to high salinity. The transcripts of salt stress-responsive marker genes (COR15a, KIN1, RD29B and ERD10) were overactivated in AtLEA14 overexpressing lines compared with those in wild type plants under normal or salt stress conditions. In vivo and in vitro analysis showed that AtLEA14 could effectively stabilize AtPP2-B11, an important E3 ligase. These results suggested that AtLEA14 had important protective functions under salt stress conditions in Arabidopsis.

  1. Enhancing bile tolerance improves survival and persistence of Bifidobacterium and Lactococcus in the murine gastrointestinal tract

    PubMed Central

    Watson, Debbie; Sleator, Roy D; Hill, Colin; Gahan, Cormac GM

    2008-01-01

    Background The majority of commensal gastrointestinal bacteria used as probiotics are highly adapted to the specialised environment of the large bowel. However, unlike pathogenic bacteria; they are often inadequately equipped to endure the physicochemical stresses of gastrointestinal (GI) delivery in the host. Herein we outline a patho-biotechnology strategy to improve gastric delivery and host adaptation of a probiotic strain Bifidobacterium breve UCC2003 and the generally regarded as safe (GRAS) organism Lactococcus lactis NZ9000. Results In vitro bile tolerance of both strains was significantly enhanced (P < 0.001), following heterologous expression of the Listeria monocytogenes bile resistance mechanism BilE. Strains harbouring bilE were also recovered at significantly higher levels (P < 0.001), than control strains from the faeces and intestines of mice (n = 5), following oral inoculation. Furthermore, a B. breve strain expressing bilE demonstrated increased efficacy relative to the wild-type strain in reducing oral L. monocytogenes infection in mice. Conclusion Collectively the data indicates that bile tolerance can be enhanced in Bifidobacterium and Lactococcus species through rational genetic manipulation and that this can significantly improve delivery to and colonisation of the GI tract. PMID:18844989

  2. Evolutionary engineering of Saccharomyces cerevisiae for enhanced tolerance to hydrolysates of lignocellulosic biomass.

    PubMed

    Almario, María P; Reyes, Luis H; Kao, Katy C

    2013-10-01

    Lignocellulosic biomass has become an important feedstock to mitigate current ethical and economical concerns related to the bio-based production of fuels and chemicals. During the pre-treatment and hydrolysis of the lignocellulosic biomass, a complex mixture of sugars and inhibitors are formed. The inhibitors interfere with microbial growth and product yields. This study uses an adaptive laboratory evolution method called visualizing evolution in real-time (VERT) to uncover the molecular mechanisms associated with tolerance to hydrolysates of lignocellulosic biomass in Saccharomyces cerevisiae. VERT enables a more rational scheme for isolating adaptive mutants for characterization and molecular analyses. Subsequent growth kinetic analyses of the mutants in individual and combinations of common inhibitors present in hydrolysates (acetic acid, furfural, and hydroxymethylfurfural) showed differential levels of resistance to different inhibitors, with enhanced growth rates up to 57%, 12%, 22%, and 24% in hydrolysates, acetic acid, HMF and furfural, respectively. Interestingly, some of the adaptive mutants exhibited reduced fitness in the presence of individual inhibitors, but showed enhanced fitness in the presence of combinations of inhibitors compared to the parental strains. Transcriptomic analysis revealed different mechanisms for resistance to hydrolysates and a potential cross adaptation between oxidative stress and hydrolysates tolerance in several of the mutants. PMID:23613173

  3. Silicon Enhances Water Stress Tolerance by Improving Root Hydraulic Conductance in Solanum lycopersicum L.

    PubMed Central

    Shi, Yu; Zhang, Yi; Han, Weihua; Feng, Ru; Hu, Yanhong; Guo, Jia; Gong, Haijun

    2016-01-01

    Silicon (Si) can improve drought tolerance in plants, but the mechanism is still not fully understood. Previous research has been concentrating on Si’s role in leaf water maintenance in Si accumulators, while little information is available on its role in water uptake and in less Si-accumulating plants. Here, we investigated the effects of Si on root water uptake and its role in decreasing oxidative damage in relation to root hydraulic conductance in tomato (Solanum lycopersicum ‘Zhongza No.9’) under water stress. Tomato seedlings were subjected to water stress induced by 10% (w/v) polyethylene glycol-6000 in the absence or presence of 2.5 mM added silicate. The results showed that Si addition ameliorated the inhibition in tomato growth and photosynthesis, and improved water status under water stress. The root hydraulic conductance of tomato plants was decreased under water stress, and it was significantly increased by added Si. There was no significant contribution of osmotic adjustment in Si-enhanced root water uptake under water stress. The transcriptions of plasma membrane aquaporin genes were not obviously changed by Si under water stress. Water stress increased the production of reactive oxygen species and induced oxidative damage, while added Si reversed these. In addition, Si addition increased the activities of superoxide dismutase and catalase and the levels of ascorbic acid and glutathione in the roots under stress. It is concluded that Si enhances the water stress tolerance via enhancing root hydraulic conductance and water uptake in tomato plants. Si-mediated decrease in membrane oxidative damage may have contributed to the enhanced root hydraulic conductance. PMID:26941762

  4. Silicon Enhances Water Stress Tolerance by Improving Root Hydraulic Conductance in Solanum lycopersicum L.

    PubMed

    Shi, Yu; Zhang, Yi; Han, Weihua; Feng, Ru; Hu, Yanhong; Guo, Jia; Gong, Haijun

    2016-01-01

    Silicon (Si) can improve drought tolerance in plants, but the mechanism is still not fully understood. Previous research has been concentrating on Si's role in leaf water maintenance in Si accumulators, while little information is available on its role in water uptake and in less Si-accumulating plants. Here, we investigated the effects of Si on root water uptake and its role in decreasing oxidative damage in relation to root hydraulic conductance in tomato (Solanum lycopersicum 'Zhongza No.9') under water stress. Tomato seedlings were subjected to water stress induced by 10% (w/v) polyethylene glycol-6000 in the absence or presence of 2.5 mM added silicate. The results showed that Si addition ameliorated the inhibition in tomato growth and photosynthesis, and improved water status under water stress. The root hydraulic conductance of tomato plants was decreased under water stress, and it was significantly increased by added Si. There was no significant contribution of osmotic adjustment in Si-enhanced root water uptake under water stress. The transcriptions of plasma membrane aquaporin genes were not obviously changed by Si under water stress. Water stress increased the production of reactive oxygen species and induced oxidative damage, while added Si reversed these. In addition, Si addition increased the activities of superoxide dismutase and catalase and the levels of ascorbic acid and glutathione in the roots under stress. It is concluded that Si enhances the water stress tolerance via enhancing root hydraulic conductance and water uptake in tomato plants. Si-mediated decrease in membrane oxidative damage may have contributed to the enhanced root hydraulic conductance. PMID:26941762

  5. Stabilization of lignin peroxidases in white rot fungi by tryptophan.

    PubMed Central

    Collins, P J; Field, J A; Teunissen, P; Dobson, A D

    1997-01-01

    Supplementation of various cultures of white rot fungi with tryptophan was found to have a large stimulatory effect on lignin peroxidase activity levels. This enhancement was greater than that observed in the presence of the lignin peroxidase recycling agent veratryl alcohol. Using reverse transcription-PCR, we found that tryptophan does not act to induce lignin peroxidase expression at the level of gene transcription. Instead, the activity enhancement observed is likely to result from the protective effect of tryptophan against H2O2 inactivation. In experiments using a partially purified lignin peroxidase preparation, tryptophan and its derivative indole were determined to function in the same way as veratryl alcohol in converting compound II, an oxidized form of lignin peroxidase, to ferric enzyme, thereby completing the catalytic cycle. Furthermore, tryptophan was found to be a better substrate for lignin peroxidase than veratryl alcohol. Inclusion of either tryptophan or indole enhanced the oxidation of the azo dyes methyl orange and Eriochrome blue black. Stimulation of azo dye oxidations by veratryl alcohol has previously been shown to be due to its enzyme recycling function. Our data allow us to propose that tryptophan stabilizes lignin peroxidase by acting as a reductant for the enzyme. PMID:9212404

  6. Overexpression of MtCAS31 enhances drought tolerance in transgenic Arabidopsis by reducing stomatal density.

    PubMed

    Xie, Can; Zhang, Rongxue; Qu, Yueting; Miao, Zhenyan; Zhang, Yunqin; Shen, Xiaoye; Wang, Tao; Dong, Jiangli

    2012-07-01

    • Dehydrins are a type of late embryogenesis abundant protein. Some dehydrins are involved in the response to various abiotic stresses. Accumulation of dehydrins enhances the drought, cold and salt tolerances of transgenic plants, although the underlying mechanism is unclear. MtCAS31 (Medicago Truncatula cold-acclimation specific protein 31) is a Y(2)K(4)-type dehydrin that was isolated from Medicago truncatula. • We analyzed the subcellular and histochemical localization of MtCAS31, and the expression patterns of MtCAS31 under different stresses. Transgenic Arabidopsis that overexpressed MtCAS31 was used to determine the function of MtCAS31. A yeast two-hybrid assay was used to screen potential proteins that could interact with MtCAS31. The interaction was confirmed by bimolecular fluorescence complementation (BiFC) assay. • After a 3-h drought treatment, the expression of MtCAS31 significantly increased 600-fold. MtCAS31 overexpression dramatically reduced stomatal density and markedly enhanced the drought tolerance of transgenic Arabidopsis. MtCAS31 could interact with AtICE1 (inducer of CBF expression 1) and the AtICE1 homologous protein Mt7g083900.1, which was identified from Medicago truncatula both in vitro and in vivo. • Our findings demonstrate that a dehydrin induces decreased stomatal density. Most importantly, the interaction of MtCAS31 with AtICE1 plays a role in stomatal development. We hypothesize that the interaction of MtCAS31 and AtICE1 caused the decrease in stomatal density to enhance the drought resistance of transgenic Arabidopsis. PMID:22510066

  7. Enhanced response to enzyme replacement therapy in Pompe disease after the induction of immune tolerance.

    PubMed

    Sun, Baodong; Bird, Andrew; Young, Sarah P; Kishnani, Priya S; Chen, Y-T; Koeberl, Dwight D

    2007-11-01

    Pompe disease, which results from mutations in the gene encoding the glycogen-degrading lysosomal enzyme acid alpha -glucosidase (GAA) (also called "acid maltase"), causes death in early childhood related to glycogen accumulation in striated muscle and an accompanying infantile-onset cardiomyopathy. The efficacy of enzyme replacement therapy (ERT) with recombinant human GAA was demonstrated during clinical trials that prolonged subjects' overall survival, prolonged ventilator-free survival, and also improved cardiomyopathy, which led to broad-label approval by the U.S. Food and Drug Administration. Patients who lack any residual GAA expression and are deemed negative for cross-reacting immunologic material (CRIM) have a poor response to ERT. We previously showed that gene therapy with an adeno-associated virus (AAV) vector containing a liver-specific promoter elevated the GAA activity in plasma and prevented anti-GAA antibody formation in immunocompetent GAA-knockout mice for 18 wk, predicting that liver-specific expression of human GAA with the AAV vector would induce immune tolerance and enhance the efficacy of ERT. In this study, a very low number of AAV vector particles was administered before initiation of ERT, to prevent the antibody response in GAA-knockout mice. A robust antibody response was provoked in naive GAA-knockout mice by 6 wk after a challenge with human GAA and Freund's adjuvant; in contrast, administration of the AAV vector before the GAA challenge prevented the antibody response. Most compellingly, the antibody response was prevented by AAV vector administration during the 12 wk of ERT, and the efficacy of ERT was thereby enhanced. Thus, AAV vector-mediated gene therapy induced a tolerance to introduced GAA, and this strategy could enhance the efficacy of ERT in CRIM-negative patients with Pompe disease and in patients with other lysosomal storage diseases. PMID:17924344

  8. Enhanced Response to Enzyme Replacement Therapy in Pompe Disease after the Induction of Immune Tolerance

    PubMed Central

    Sun, Baodong ; Bird, Andrew ; Young, Sarah P. ; Kishnani, Priya S. ; Chen, Y.-T. ; Koeberl, Dwight D. 

    2007-01-01

    Pompe disease, which results from mutations in the gene encoding the glycogen-degrading lysosomal enzyme acid α-glucosidase (GAA) (also called “acid maltase”), causes death in early childhood related to glycogen accumulation in striated muscle and an accompanying infantile-onset cardiomyopathy. The efficacy of enzyme replacement therapy (ERT) with recombinant human GAA was demonstrated during clinical trials that prolonged subjects’ overall survival, prolonged ventilator-free survival, and also improved cardiomyopathy, which led to broad-label approval by the U.S. Food and Drug Administration. Patients who lack any residual GAA expression and are deemed negative for cross-reacting immunologic material (CRIM) have a poor response to ERT. We previously showed that gene therapy with an adeno-associated virus (AAV) vector containing a liver-specific promoter elevated the GAA activity in plasma and prevented anti-GAA antibody formation in immunocompetent GAA-knockout mice for 18 wk, predicting that liver-specific expression of human GAA with the AAV vector would induce immune tolerance and enhance the efficacy of ERT. In this study, a very low number of AAV vector particles was administered before initiation of ERT, to prevent the antibody response in GAA-knockout mice. A robust antibody response was provoked in naive GAA-knockout mice by 6 wk after a challenge with human GAA and Freund’s adjuvant; in contrast, administration of the AAV vector before the GAA challenge prevented the antibody response. Most compellingly, the antibody response was prevented by AAV vector administration during the 12 wk of ERT, and the efficacy of ERT was thereby enhanced. Thus, AAV vector–mediated gene therapy induced a tolerance to introduced GAA, and this strategy could enhance the efficacy of ERT in CRIM-negative patients with Pompe disease and in patients with other lysosomal storage diseases. PMID:17924344

  9. Ellagic acid enhances morphine analgesia and attenuates the development of morphine tolerance and dependence in mice.

    PubMed

    Mansouri, Mohammad Taghi; Naghizadeh, Bahareh; Ghorbanzadeh, Behnam

    2014-10-15

    According to our previous study, ellagic acid has both dose-related central and peripheral antinociceptive effect through the opioidergic and l-arginine-NO-cGMP-ATP sensitive K(+) channel pathways. In the present study, the systemic antinociceptive effects of ellagic acid in animal models of pain, and functional interactions between ellagic acid and morphine in terms of analgesia, tolerance and dependence were investigated. Ellagic acid (1-30mg/kg; i.p.) showed significant and dose-dependent antinociceptive effects in the acetic acid-induced writhing test. Intraperitoneal ellagic acid acutely interacted with morphine analgesia in a synergistic manner in this assay. Ellagic acid (1-10mg/kg; i.p.) also exerted analgesic activity in the hot-plate test. Pre-treatment with naloxone (1mg/kg; i.p.) significantly reversed ellagic acid, morphine as well as ellagic acid-morphine combination-induced antinociceptin in these two tests. More importantly, when co-administered with morphine, ellagic acid (1-10mg/kg) effectively blocked the development of tolerance to morphine analgesia in the hot-plate test. Likewise, ellagic acid dose-dependently prevented naloxone-precipitated withdrawal signs including jumping and weight loss. Ellagic acid treatment (1-30mg/kg; i.p.) had no significant effect on the locomotion activity of animals using open-field task. Therefore, these results showed that ellagic acid has notable systemic antinociceptive activity for both tonic and phasic pain models. Altogether, ellagic acid might be used in pain relief alone or in combination with opioid drugs because of enhancing morphine analgesia and preventing morphine-induced tolerance to analgesia and dependence. PMID:25179576

  10. Enhanced Boron Tolerance in Plants Mediated by Bidirectional Transport Through Plasma Membrane Intrinsic Proteins

    PubMed Central

    Mosa, Kareem A.; Kumar, Kundan; Chhikara, Sudesh; Musante, Craig; White, Jason C.; Dhankher, Om Parkash

    2016-01-01

    High boron (B) concentration is toxic to plants that limit plant productivity. Recent studies have shown the involvement of the members of major intrinsic protein (MIP) family in controlling B transport. Here, we have provided experimental evidences showing the bidirectional transport activity of rice OsPIP1;3 and OsPIP2;6. Boron transport ability of OsPIP1;3 and OsPIP2;6 were displayed in yeast HD9 mutant strain (∆fps1∆acr3∆ycf1) as a result of increased B sensitivity, influx and accumulation by OsPIP1;3, and rapid efflux activity by OsPIP2;6. RT-PCR analysis showed strong upregulation of OsPIP1;3 and OsPIP2;6 transcripts in roots by B toxicity. Transgenic Arabidopsis lines overexpressing OsPIP1;3 and OsPIP2;6 exhibited enhanced tolerance to B toxicity. Furthermore, B concentration was significantly increased after 2 and 3 hours of tracer boron (10B) treatment. Interestingly, a rapid efflux of 10B from the roots of the transgenic plants was observed within 1 h of 10B treatment. Boron tolerance in OsPIP1;3 and OsPIP2;6 lines was inhibited by aquaporin inhibitors, silver nitrate and sodium azide. Our data proved that OsPIP1;3 and OsPIP2;6 are indeed involved in both influx and efflux of boron transport. Manipulation of these PIPs could be highly useful in improving B tolerance in crops grown in high B containing soils. PMID:26902738

  11. Enhanced Boron Tolerance in Plants Mediated by Bidirectional Transport Through Plasma Membrane Intrinsic Proteins.

    PubMed

    Mosa, Kareem A; Kumar, Kundan; Chhikara, Sudesh; Musante, Craig; White, Jason C; Dhankher, Om Parkash

    2016-01-01

    High boron (B) concentration is toxic to plants that limit plant productivity. Recent studies have shown the involvement of the members of major intrinsic protein (MIP) family in controlling B transport. Here, we have provided experimental evidences showing the bidirectional transport activity of rice OsPIP1;3 and OsPIP2;6. Boron transport ability of OsPIP1;3 and OsPIP2;6 were displayed in yeast HD9 mutant strain (∆fps1∆acr3∆ycf1) as a result of increased B sensitivity, influx and accumulation by OsPIP1;3, and rapid efflux activity by OsPIP2;6. RT-PCR analysis showed strong upregulation of OsPIP1;3 and OsPIP2;6 transcripts in roots by B toxicity. Transgenic Arabidopsis lines overexpressing OsPIP1;3 and OsPIP2;6 exhibited enhanced tolerance to B toxicity. Furthermore, B concentration was significantly increased after 2 and 3 hours of tracer boron ((10)B) treatment. Interestingly, a rapid efflux of (10)B from the roots of the transgenic plants was observed within 1 h of (10)B treatment. Boron tolerance in OsPIP1;3 and OsPIP2;6 lines was inhibited by aquaporin inhibitors, silver nitrate and sodium azide. Our data proved that OsPIP1;3 and OsPIP2;6 are indeed involved in both influx and efflux of boron transport. Manipulation of these PIPs could be highly useful in improving B tolerance in crops grown in high B containing soils. PMID:26902738

  12. Testosterone Enhances Risk Tolerance without Altering Motor Impulsivity in Male Rats

    PubMed Central

    Cooper, Sarah E.; Goings, Sydney P.; Kim, Jessica Y.; Wood, Ruth I.

    2014-01-01

    Summary Anabolic-androgenic steroids (AAS) increase impulsive and uncontrolled aggressive (‘roid rage) in humans and enhance agonistic behavior in animals. However, the underlying mechanisms for AAS-induced aggression remain unclear. Potential contributing elements include an increase risk-taking and/or motor impulsivity due to AAS. This study addressed the effects of chronic high-dose testosterone on risk tolerance using a risky decision-making task (RDT) and motor impulsivity with a go/no-go task in operant chambers. Male Long-Evans rats were treated for at least 4 weeks with testosterone (7.5mg/kg) or vehicle beginning in late adolescence. Testosterone was used because it is popular among human AAS users. In RDT testing, one lever was paired with delivery of a small “safe” food reward, while the other was paired with a large “risky” reward associated with an increasing risk of footshock (0, 25, 50, 75, 100%) in successive test blocks. Three shock intensities were used: 1.0, 1.2, and 1.4 mA/kg. As shock intensity and risk of shock increased, preference for the lever signifying a large reward significantly declined for both vehicle- and testosterone-treated rats (p<0.05). There was also a significant effect of drug (p<0.05), where testosterone-treated rats showed greater preference for the large reward, compared to vehicle- treated controls. Increased preference for the large reward, despite risk of footshock, is consistent with increased risk tolerance. In go/no-go testing, rats were trained to press a single lever if the go cue was presented (stimulus light) or to refrain from pressing during the no-go cue (tone). There was no effect of testosterone on pre-cue responses, or performance in go and no-go trials. These results suggest that AAS may increase risk-tolerance without altering motor impulsivity. PMID:24485492

  13. Molecular Phylogeny of Heme Peroxidases

    NASA Astrophysics Data System (ADS)

    Zámocký, Marcel; Obinger, Christian

    All currently available gene sequences of heme peroxidases can be phylogenetically divided in two superfamilies and three families. In this chapter, the phylogenetics and genomic distribution of each group are presented. Within the peroxidase-cyclooxygenase superfamily, the main evolutionary direction developed peroxidatic heme proteins involved in the innate immune defense system and in biosynthesis of (iodinated) hormones. The peroxidase-catalase superfamily is widely spread mainly among bacteria, fungi, and plants, and particularly in Class I led to the evolution of bifunctional catalase-peroxidases. Its numerous fungal representatives of Class II are involved in carbon recycling via lignin degradation, whereas Class III secretory peroxidases from algae and plants are included in various forms of secondary metabolism. The family of di-heme peroxidases are predominantly bacteria-inducible enzymes; however, a few corresponding genes were also detected in archaeal genomes. Four subfamilies of dyp-type peroxidases capable of degradation of various xenobiotics are abundant mainly among bacteria and fungi. Heme-haloperoxidase genes are widely spread among sac and club fungi, but corresponding genes were recently found also among oomycetes. All described families herein represent heme peroxidases of broad diversity in structure and function. Our accumulating knowledge about the evolution of various enzymatic functions and physiological roles can be exploited in future directed evolution approaches for engineering peroxidase genes de novo for various demands.

  14. Overexpression of beta-carotene hydroxylase enhances stress tolerance in Arabidopsis.

    PubMed

    Davison, P A; Hunter, C N; Horton, P

    2002-07-11

    Plant stress caused by extreme environmental conditions is already a principal reason for yield reduction in crops. The threat of global environment change makes it increasingly important to generate crop plants that will withstand such conditions. Stress, particularly stress caused by increased sunlight, leads to the production of reactive oxygen species that cause photo-oxidative cell damage. Carotenoids, which are present in the membranes of all photosynthetic organisms, help protect against such light-dependent oxidative damage. In plants, the xanthophyll cycle (the reversible interconversion of two carotenoids, violaxanthin and zeaxanthin) has a key photoprotective role and is therefore a promising target for genetic engineering to enhance stress tolerance. Here we show that in Arabidopsis thaliana overexpression of the chyB gene that encodes beta-carotene hydroxylase--an enzyme in the zeaxanthin biosynthetic pathway--causes a specific twofold increase in the size of the xanthophyll cycle pool. The plants are more tolerant to conditions of high light and high temperature, as shown by reduced leaf necrosis, reduced production of the stress indicator anthocyanin and reduced lipid peroxidation. Stress protection is probably due to the function of zeaxanthin in preventing oxidative damage of membranes. PMID:12110893

  15. Enhanced tolerance to salt stress in transgenic rice that overexpresses chloroplast glutamine synthetase.

    PubMed

    Hoshida, H; Tanaka, Y; Hibino, T; Hayashi, Y; Tanaka, A; Takabe, T; Takabe, T

    2000-05-01

    The potential role of photorespiration in the protection against salt stress was examined with transgenic rice plants. Oryza sativa L. cv. Kinuhikari was transformed with a chloroplastic glutamine synthetase (GS2) gene from rice. Each transgenic rice plant line showed a different accumulation level of GS2. A transgenic plant line, G39-2, which accumulated about 1.5-fold more GS2 than the control plant, had an increased photorespiration capacity. In another line, G241-12, GS2 was almost lost and photorespiration activity could not be detected. Fluorescence quenching analysis revealed that photorespiration could prevent the over-reduction of electron transport systems. When exposed to 150 mM NaCl for 2 weeks, the control rice plants completely lost photosystem II activity, but G39-2 plants retained more than 90% activity after the 2-week treatment, whereas G241-12 plants lost these activities within one week. In the presence of isonicotinic acid hydrazide, an inhibitor of photorespiration, G39-2 showed the same salt tolerance as the control plants. The intracellular contents of NH4+ and Na+ in the stressed plants correlated well with the levels of GS2. Thus, the enhancement of photorespiration conferred resistance to salt in rice plants. Preliminary results suggest chilling tolerance in the transformant. PMID:10949377

  16. Overexpression of the wheat aquaporin gene, TaAQP7, enhances drought tolerance in transgenic tobacco.

    PubMed

    Zhou, Shiyi; Hu, Wei; Deng, Xiaomin; Ma, Zhanbing; Chen, Lihong; Huang, Chao; Wang, Chen; Wang, Jie; He, Yanzhen; Yang, Guangxiao; He, Guangyuan

    2012-01-01

    Aquaporin (AQP) proteins have been shown to transport water and other small molecules through biological membranes, which is crucial for plants to combat stress caused by drought. However, the precise role of AQPs in drought stress response is not completely understood in plants. In this study, a PIP2 subgroup gene AQP, designated as TaAQP7, was cloned and characterized from wheat. Expression of TaAQP7-GFP fusion protein revealed its localization in the plasma membrane. TaAQP7 exhibited high water channel activity in Xenopus laevis oocytes and TaAQP7 transcript was induced by dehydration, and treatments with polyethylene glycol (PEG), abscisic acid (ABA) and H(2)O(2). Further, TaAQP7 was upregulated after PEG treatment and was blocked by inhibitors of ABA biosynthesis, implying that ABA signaling was involved in the upregulation of TaAQP7 after PEG treatment. Overexpression of TaAQP7 increased drought tolerance in tobacco. The transgenic tobacco lines had lower levels of malondialdehyde (MDA) and H(2)O(2), and less ion leakage (IL), but higher relative water content (RWC) and superoxide dismutase (SOD) and catalase (CAT) activities when compared with the wild type (WT) under drought stress. Taken together, our results show that TaAQP7 confers drought stress tolerance in transgenic tobacco by increasing the ability to retain water, reduce ROS accumulation and membrane damage, and enhance the activities of antioxidants. PMID:23285044

  17. Enhanced salt tolerance in tomato plants constitutively expressing heat-shock protein in the endoplasmic reticulum.

    PubMed

    Fu, C; Liu, X X; Yang, W W; Zhao, C M; Liu, J

    2016-01-01

    The accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) causes ER stress and activates the unfolded protein response (UPR) signaling pathway. The UPR signaling pathway is associated with plant responses to adverse environmental conditions. Thus, changes in the UPR signaling pathway might affect plant abiotic tolerance. Here, the role of ER small heat-shock protein (ER-sHSP) in improving plant resistance to salt stress was explored. Under salt stress conditions, ER-sHSP transgenic plants were found to have more vigorous roots, maintain a higher relative water content, absorb less Na(+), accumulate more osmolytes and Ca(2+), and sustain less damage to the photosystem, compared to wild-type non-transgenic plants. Furthermore, we found that the constitutive expression of ER-sHSP under salt stress depressed the expression of other ER molecular chaperones. These results indicate that the constitutive expression of ER-sHSP enhanced salinity tolerance of tomato plants significantly, and alleviated the ER stress caused by the salt stress in plant cells. PMID:27421016

  18. In situ study of defect migration kinetics in nanoporous Ag with enhanced radiation tolerance

    PubMed Central

    Sun, C.; Bufford, D.; Chen, Y.; Kirk, M. A.; Wang, Y. Q.; Li, M.; Wang, H.; Maloy, S. A.; Zhang, X.

    2014-01-01

    Defect sinks, such as grain boundaries and phase boundaries, have been widely accepted to improve the irradiation resistance of metallic materials. However, free surface, an ideal defect sink, has received little attention in bulk materials as surface-to-volume ratio is typically low. Here by using in situ Kr ion irradiation technique in a transmission electron microscope, we show that nanoporous (NP) Ag has enhanced radiation tolerance. Besides direct evidence of free surface induced frequent removal of various types of defect clusters, we determined, for the first time, the global and instantaneous diffusivity of defect clusters in both coarse-grained (CG) and NP Ag. Opposite to conventional wisdom, both types of diffusivities are lower in NP Ag. Such a surprise is largely related to the reduced interaction energy between isolated defect clusters in NP Ag. Determination of kinetics of defect clusters is essential to understand and model their migration and clustering in irradiated materials. PMID:24435181

  19. In situ study of defect migration kinetics in nanoporous Ag with enhanced radiation tolerance.

    PubMed

    Sun, C; Bufford, D; Chen, Y; Kirk, M A; Wang, Y Q; Li, M; Wang, H; Maloy, S A; Zhang, X

    2014-01-01

    Defect sinks, such as grain boundaries and phase boundaries, have been widely accepted to improve the irradiation resistance of metallic materials. However, free surface, an ideal defect sink, has received little attention in bulk materials as surface-to-volume ratio is typically low. Here by using in situ Kr ion irradiation technique in a transmission electron microscope, we show that nanoporous (NP) Ag has enhanced radiation tolerance. Besides direct evidence of free surface induced frequent removal of various types of defect clusters, we determined, for the first time, the global and instantaneous diffusivity of defect clusters in both coarse-grained (CG) and NP Ag. Opposite to conventional wisdom, both types of diffusivities are lower in NP Ag. Such a surprise is largely related to the reduced interaction energy between isolated defect clusters in NP Ag. Determination of kinetics of defect clusters is essential to understand and model their migration and clustering in irradiated materials. PMID:24435181

  20. Overexpression of SpCBL6, a calcineurin B-like protein of Stipa purpurea, enhanced cold tolerance and reduced drought tolerance in transgenic Arabidopsis.

    PubMed

    Zhou, Yanli; Cheng, Ying; Yang, Yunqiang; Li, Xiong; Supriyo, Basak; Sun, Xudong; Yang, Yongping

    2016-09-01

    The purpose of the present study was to characterize SpCBL6 (GenBank accession number: KT780442) from Stipa purpurea and elucidate the function of this protein in abiotic stress. The full-length cDNA of SpCBL6 was isolated from S. purpurea by rapid amplification of cDNA ends methods. Laser confocal microscopy was used to analyze the subcellular localization of SpCBL6. The constructs of 35S:GFP-SpCBL6 was used to transform wild-type (WT) Arabidopsis plants (ecotype Columbia-0) with the floral dip method. Quantitative reverse-transcription PCR (qRT-PCR), water potential, photosynthetic efficiency (F v/F m), and ion leakage was performed to investigate the role of SpCBL6 in abiotic stress. The open reading frame of SpCBL6 contains 681 bp nucleotides and encodes a 227-amino acid polypeptide. Phylogenetic analysis indicated that SpCBL6 showed the highest similarity with rice OsCBL6. SpCBL6 transcripts were induced by freezing and drought treatments. Subcellular localization analysis showed that SpCBL6 was located in membrane of protoplast. Overexpression of SpCBL6 in Arabidopsis thaliana demonstrated that the transgenic plants were more tolerant to cold treatment, but less tolerant to drought, compared with the plants. qRT-PCR analysis showed that the drought stress marker genes were inhibited in transgenic plants, whereas the cold stress marker genes were enhanced. Further analysis showed that SpCBL6-overexpressing plants showed enhanced water potential, photosynthetic efficiency (F v/F m), and reduced ion leakage compared with the wild-type after cold treatment. Collectively, these results indicate that SpCBL6, a new member of the CBL gene family isolated from S. purpurea, enhances cold tolerance and reduces drought tolerance in plants. PMID:27393148

  1. Overexpression of a cotton annexin gene, GhAnn1, enhances drought and salt stress tolerance in transgenic cotton.

    PubMed

    Zhang, Feng; Li, Shufen; Yang, Shuming; Wang, Like; Guo, Wangzhen

    2015-01-01

    Plant annexins are members of a diverse, multigene protein family that has been associated with a variety of cellular processes and responses to abiotic stresses. GhAnn1, which encodes a putative annexin protein, was isolated from a cotton (Gossypium hirsutum L. acc 7235) cDNA library. Tissue-specific expression showed that GhAnn1 is expressed at differential levels in all tissues examined and strongly induced by various phytohormones and abiotic stress. In vivo and in vitro subcellular localization suggested that GhAnn1 is located in the plasma membrane. In response to drought and salt stress, transgenic cotton plants overexpressing GhAnn1 showed significantly higher germination rates, longer roots, and more vigorous growth than wild-type plants. In addition, plants overexpressing GhAnn1 had higher total chlorophyll content, lower lipid peroxidation levels, increased peroxidase activities, and higher levels of proline and soluble sugars, all of which contributed to increased salt and drought stress tolerance. However, transgenic cotton plants in which the expression of GhAnn1 was suppressed showed the opposite results compared to the overexpressing plants. These findings demonstrated that GhAnn1 plays an important role in the abiotic stress response, and that overexpression of GhAnn1 in transgenic cotton improves salt and drought tolerance. PMID:25330941

  2. Intermediate-field two-photon absorption enhancement by shaped femtosecond pulses: Tolerance to phase deviation from perfect antisymmetry

    SciTech Connect

    Chuntonov, Lev; Rybak, Leonid; Gandman, Andrey; Amitay, Zohar

    2010-04-15

    We study in detail the coherent interference mechanism leading to the intermediate-field two-photon absorption enhancement recently found for shaped femtosecond pulses with spectral phases that are antisymmetric around one-half of the transition frequency. We particularly investigate the tolerance of the phenomenon to the phase deviation from perfect antisymmetry. We theoretically and experimentally find that this tolerance increases as the field strength increases. For the present Na excitation, the enhancement occurs even when {approx}30% of the phase pattern is not antisymmetric. Our findings are of particular importance for multichannel coherent control scenarios.

  3. GDP-D-mannose pyrophosphorylase from Pogonatherum paniceum enhances salinity and drought tolerance of transgenic tobacco.

    PubMed

    Ai, Taobo; Liao, Xuehong; Li, Rui; Fan, Linhong; Luo, Fengxue; Xu, Ying; Wang, Shenghua

    2016-01-01

    Pogonatherum paniceum is a highly drought- and salt-tolerant plant species that is typically used for ecological restoration and the conservation of soil and water in many countries. Understanding the molecular mechanisms underlying plant abiotic stress responses, especially to salinity and drought stresses, in species such as P. paniceum could be important to broader crop improvement efforts. GDP-D-mannose pyrophosphorylase (GMPase) is the limiting enzyme in the synthesis of L-ascorbic acid (AsA), which plays a crucial role in the detoxification of reactive oxygen species (ROS). We have cloned and characterized the cDNA of the PpGMP gene of P. paniceum encoding a GMPase. The full-length cDNA sequence contains 1411 nucleotides encoding a putative protein with 361 amino acid residues and an approximate molecular mass of 39.68 kDa. The GMPase transcript was up-regulated in P. paniceum plants subjected to salinity and drought stress, respectively. Transgenic tobacco expressing PpGMPase exhibited enhanced salinity and drought resistance, a higher seed germination rate, better growth performance, a higher AsA content, a more stable redox state, higher superoxide dismutase (SOD) activity, and lower levels of malonaldehyde (MDA) and H2O2 under drought and salinity stress. Taken together, expression of PpGMPase in tobacco conferred salinity and drought stress tolerance by increasing the content of AsA, thereby enhancing ROS-detoxifying functions. Thus, PpGMP is a potential candidate gene for crop improvement. PMID:27442366

  4. Glassy carbon electrode modified with horse radish peroxidase/organic nucleophilic-functionalized carbon nanotube composite for enhanced electrocatalytic oxidation and efficient voltammetric sensing of levodopa.

    PubMed

    Shoja, Yalda; Rafati, Amir Abbas; Ghodsi, Javad

    2016-01-01

    A novel and selective enzymatic biosensor was designed and constructed for voltammetric determination of levodopa (L-Dopa) in aqueous media (phosphate buffer solution, pH=7). Biosensor development was on the basis of to physically immobilizing of horse radish peroxidase (HRP) as electrochemical catalyst by sol-gel on glassy carbon electrode modified with organic nucleophilic carbon nanotube composite which in this composite p-phenylenediamine (pPDA) as organic nucleophile chemically bonded with functionalized MWCNT (MWCNT-COOH). The results of this study suggest that prepared bioorganic nucleophilic carbon nanotube composite (HRP/MWCNT-pPDA) shows fast electron transfer rate for electro oxidation of L-Dopa because of its high electrochemical catalytic activity toward the oxidation of L-Dopa, more--NH2 reactive sites and large effective surface area. Also in this work we measured L-Dopa in the presence of folic acid and uric acid as interferences. The proposed biosensor was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), FT-IR spectroscopy and cyclic voltammetry (CV). The differential pulse voltammetry (DPV) was used for determination of L-Dopa from 0.1 μM to 1.9 μM with a low detection limit of 40 nM (for S/N=3) and sensitivity was about 35.5 μA/μM. Also this biosensor has several advantages such as rapid response, high stability and reproducibility. PMID:26478378

  5. Expression of an alfalfa (Medicago sativa L.) peroxidase gene in transgenic Arabidopsis thaliana enhances resistance to NaCl and H2O2.

    PubMed

    Teng, K; Xiao, G Z; Guo, W E; Yuan, J B; Li, J; Chao, Y H; Han, L B

    2016-01-01

    Peroxidases (PODs) are enzymes that play important roles in catalyzing the reduction of H2O2 and the oxidation of various substrates. They function in many different and important biological processes, such as defense mechanisms, immune responses, and pathogeny. The POD genes have been cloned and identified in many plants, but their function in alfalfa (Medicago sativa L.) is not known, to date. Based on the POD gene sequence (GenBank accession No. L36157.1), we cloned the POD gene in alfalfa, which was named MsPOD. MsPOD expression increased with increasing H2O2. The gene was expressed in all of the tissues, including the roots, stems, leaves, and flowers, particularly in stems and leaves under light/dark conditions. A subcellular analysis showed that MsPOD was localized outside the cells. Transgenic Arabidopsis with MsPOD exhibited increased resistance to H2O2 and NaCl. Moreover, POD activity in the transgenic plants was significantly higher than that in wild-type Arabidopsis. These results show that MsPOD plays an important role in resistance to H2O2 and NaCl. PMID:27323080

  6. Elevated ROS-scavenging enzymes contribute to acclimation to UV-B exposure in transplastomic tobacco plants, reducing the role of plastid peroxidases.

    PubMed

    Czégény, Gyula; Le Martret, Bénédicte; Pávkovics, Dóra; Dix, Philip J; Hideg, Éva

    2016-08-20

    Leaf peroxidases play a key role in the successful acclimation of plants to low UV-B doses. The aim of the present study was to examine whether selective enhancement of alternative chloroplast antioxidant pathways achieved by chloroplast transformation affected the need for peroxidase defense. Transplastomic tobacco lines expressing glutathione reductase in combination with either dehydroascorbate reductase or glutathione-S-transferase in their plastids exhibited better tolerance to supplemental UV-B than wild type plants. After 10days UV treatment, both the maximum and effective quantum yields of PSII decreased in the wild type by 10% but were unaffected in either of the transformed lines. Activities of total peroxidase and ascorbate peroxidase, in addition to dehydroascorbate reductase and gluthatione-S-transferase, were increased by UV in all lines. Gluthatione reductase activity was unaffected by UV in the transplastomic line engineered to have a higher constitutive level of this enzyme, but increased in the two other genotypes. However, the observed more successful acclimation required less activation of peroxidases in the doubly transformed plants than in the wild type and less increase in non-enzymatic hydroxyl radical neutralization in the dehydroascorbate reductase plus glutathione reductase fortified plants than in either of the other lines. These results highlight the fundamental role of efficient glutathione, and especially ascorbate, recycling in the chloroplast in response to exposure of plants to UV-B. They also identify chloroplast localized peroxidases among the large variety of leaf peroxidases as essential elements of defense, supporting our earlier hypothesis on hydrogen peroxide UV-B photo-cleavage as the primary mechanism behind damage. PMID:27448725

  7. Consequences of antisense down-regulation of a lignification-specific peroxidase on leaf and vascular tissue in tobacco lines demonstrating enhanced enzymic saccharification.

    PubMed

    Kavousi, Bahram; Daudi, Arsalan; Cook, Charis M; Joseleau, Jean-Paul; Ruel, Katia; Devoto, Alessandra; Bolwell, G Paul; Blee, Kristopher A

    2010-04-01

    Tobacco plants expressing an antisense construct for a cationic peroxidase, which down-regulated lignin content at the presumed level of polymerisation, have been further analysed. T(1) plants were derived from a large-scale screen of T(0) mutant lines, previously published, which identified lines demonstrating consistent lignin down-regulation. Of these, line 1074 which had the most robust changes in lignin distribution through several generations was shown to have accompanying down-regulation of transcription of most lignin biosynthesis genes, except cinnamoyl-CoA reductase. The consistent 20% reduction in lignin was not accompanied by significant gross changes in vascular polysaccharide content and composition, despite a modest up-regulation of transcripts of genes involved in cellulose and hemicellulose synthesis. Morphologically, 1074 plants have under-developed xylem with both fibers and vessels having thin cell walls and limited secondary wall thickening with an abnormal S2 layer. However, they were not compromised in overall growth. Nevertheless, these and other lines showed improved potential industrial utility through a threefold increase in enzymic saccharification efficiency compared with wild-type (wt). Therefore, they were profiled for further un-intended effects of transgenesis that might compromise their value for industrial or biofuel processes. Other phenotypic changes included increased leaf thickness and bifurcation at the tip of the leaf. wt-Plants had smaller chloroplasts and higher stomatal numbers than mutants. Transgenic lines also showed a variable leaf pigment distribution with light-green areas that contained measurably less chlorophyll a, b, and carotenoids. Changes in epidermal pavement cells of mutant lines were also observed after exposure to various chemicals, while wt leaves retained their structural integrity. Despite these changes, the mutant plants grew and were viable indicating that lignification patterns can be manipulated

  8. Maize peroxidase Px5 has a highly conserved sequence in inbreds resistant to mycotoxin producing fungi which enhances fungal and insect resistance.

    PubMed

    Dowd, Patrick F; Johnson, Eric T

    2016-01-01

    Mycotoxin presence in maize causes health and economic issues for humans and animals. Although many studies have investigated expression differences of genes putatively governing resistance to producing fungi, few have confirmed a resistance role, or examined putative resistance gene structure in more than a couple of inbreds. The pericarp expression of maize Px5 has previously been associated with resistance to Aspergillus flavus growth and insects in a set of inbreds. Genes from 14 different inbreds that included ones with resistance and susceptibility to A. flavus, Fusarium proliferatum, F. verticillioides and F. graminearum and/or mycotoxin production were cloned using high fidelity enzymes, and sequenced. The sequence of Px5 from all resistant inbreds was identical, except for a single base change in two inbreds, only one of which affected the amino acid sequence. Conversely, the Px5 sequence from several susceptible inbreds had several base variations, some of which affected amino acid sequence that would potentially alter secondary structure, and thus enzyme function. The sequence of the maize peroxidase Px5 common to inbreds resistant to mycotoxigenic fungi was overexpressed in maize callus. Callus transformants overexpressing the gene caused significant reductions in growth for fall armyworms, corn earworms, and F. graminearum compared to transformant callus with a β-glucuronidase gene. This study demonstrates rarer transcripts of potential resistance genes overlooked by expression screens can be identified by sequence comparisons. A role in pest resistance can be verified by callus expression of the candidate genes, which can thereby justify larger scale transformation and regeneration of transgenic plants expressing the resistance gene for further evaluation. PMID:26659597

  9. Enhanced neuroendocrine response to insulin tolerance test performed under increased ambient temperature.

    PubMed

    Jezová, D; Kvetnanský, R; Nazar, K; Vigas, M

    1998-01-01

    The hypothesis that an increase in ambient temperature modulates neuroendocrine response in clinically used provocative pituitary function tests was verified. Healthy male volunteers were subjected to insulin tolerance tests in two randomized trials. In the first trial hypoglycemia was induced by a bolus injection of insulin (0.1 U per kg of BW, i.v.) at room temperature. In the second trial, the subjects were exposed to increased ambient temperature for 45 min before insulin injection and for 45 min thereafter. The environmental temperature was selected to increase body temperature less than 1C. Under conditions of increased temperature basal hormone levels as measured in antecubital venous blood samples failed to be modified and the hypoglycemia was less severe. Nevertheless, the responses of most (beta-endorphin, ACTH, prolactin, catecholamines), but not all (growth hormone, cortisol), hormones to hypoglycemia were exaggerated. The remarkable increase in ACTH and beta-endorphin release was not accompanied by concomitant increase of plasma cortisol response. The sympathetic-adrenomedullary system was significantly activated, which was manifested particularly by enhanced norepinephrine release. Growth hormone response to hypoglycemia was not modified, while that of prolactin was enhanced. Thus during evaluation of neuroendocrine function under clinical conditions, changes in ambient and body temperature should not be underestimated. PMID:9766253

  10. Melatonin enhances plant growth and abiotic stress tolerance in soybean plants

    PubMed Central

    Wei, Wei; Li, Qing-Tian; Chu, Ya-Nan; Reiter, Russel J.; Yu, Xiao-Min; Zhu, Dan-Hua; Zhang, Wan-Ke; Ma, Biao; Lin, Qing; Zhang, Jin-Song; Chen, Shou-Yi

    2015-01-01

    Melatonin is a well-known agent that plays multiple roles in animals. Its possible function in plants is less clear. In the present study, we tested the effect of melatonin (N-acetyl-5-methoxytryptamine) on soybean growth and development. Coating seeds with melatonin significantly promoted soybean growth as judged from leaf size and plant height. This enhancement was also observed in soybean production and their fatty acid content. Melatonin increased pod number and seed number, but not 100-seed weight. Melatonin also improved soybean tolerance to salt and drought stresses. Transcriptome analysis revealed that salt stress inhibited expressions of genes related to binding, oxidoreductase activity/process, and secondary metabolic processes. Melatonin up-regulated expressions of the genes inhibited by salt stress, and hence alleviated the inhibitory effects of salt stress on gene expressions. Further detailed analysis of the affected pathways documents that melatonin probably achieved its promotional roles in soybean through enhancement of genes involved in cell division, photosynthesis, carbohydrate metabolism, fatty acid biosynthesis, and ascorbate metabolism. Our results demonstrate that melatonin has significant potential for improvement of soybean growth and seed production. Further study should uncover more about the molecular mechanisms of melatonin’s function in soybeans and other crops. PMID:25297548

  11. Employment of 4-(1,2,4-triazol-1-yl)phenol as a signal enhancer of the chemiluminescent luminol-H2O2-horseradish peroxidase reaction for detection of hepatitis C virus in real samples.

    PubMed

    Liu, Jian; Zhang, Lili; Fu, Chuanyun; Wang, Yunshan; Sun, Shanhui

    2015-12-01

    Highly sensitive detection of hepatitis C virus (HCV) in serum is a key method for diagnosing and classifying the extent of HCV infection. In this study, a p-phenol derivative, 4-(1,2,4-triazol-1-yl)phenol (4-TRP), was employed as an efficient enhancer of the luminol-hydrogen peroxide (H2O2)-horseradish peroxidase (HRP) chemiluminescence (CL) system for detection of HCV. Compared with a traditional enhancer, 4-TRP strongly enhanced CL intensity with the effect of prolonging and stabilizing light emission. The developed CL system was applied to detecting HCV core antigen (HCV-cAg) using a sandwich structure inside microwells. Our experimental results showed that there was good linear relationship between CL intensity and HCV-cAg concentration in the 0.6-3.6 pg/mL range (R = 0.99). The intra- and inter-assay coefficients of variation were 4.5-5.8% and 5.0-7.3%, respectively. In addition, sensitive determination of HCV-cAg in serum samples using the luminol-H2O2-HRP-4-TRP CL system was also feasible in clinical settings. PMID:25820800

  12. Overexpression of Rat Neurons Nitric Oxide Synthase in Rice Enhances Drought and Salt Tolerance

    PubMed Central

    Cai, Wei; Liu, Wen; Wang, Wen-Shu; Fu, Zheng-Wei; Han, Tong-Tong; Lu, Ying-Tang

    2015-01-01

    Nitric oxide (NO) has been shown to play an important role in the plant response to biotic and abiotic stresses in Arabidopsis mutants with lower or higher levels of endogenous NO. The exogenous application of NO donors or scavengers has also suggested an important role for NO in plant defense against environmental stress. In this study, rice plants under drought and high salinity conditions showed increased nitric oxide synthase (NOS) activity and NO levels. Overexpression of rat neuronal NO synthase (nNOS) in rice increased both NOS activity and NO accumulation, resulting in improved tolerance of the transgenic plants to both drought and salt stresses. nNOS-overexpressing plants exhibited stronger water-holding capability, higher proline accumulation, less lipid peroxidation and reduced electrolyte leakage under drought and salt conditions than wild rice. Moreover, nNOS-overexpressing plants accumulated less H2O2, due to the observed up-regulation of OsCATA, OsCATB and OsPOX1. In agreement, the activities of CAT and POX were higher in transgenic rice than wild type. Additionally, the expression of six tested stress-responsive genes including OsDREB2A, OsDREB2B, OsSNAC1, OsSNAC2, OsLEA3 and OsRD29A, in nNOS-overexpressing plants was higher than that in the wild type under drought and high salinity conditions. Taken together, our results suggest that nNOS overexpression suppresses the stress-enhanced electrolyte leakage, lipid peroxidation and H2O2 accumulation, and promotes proline accumulation and the expression of stress-responsive genes under stress conditions, thereby promoting increased tolerance to drought and salt stresses. PMID:26121399

  13. ATP-binding cassette transporter enhances tolerance to DDT in Tetrahymena.

    PubMed

    Ning, YingZhi; Dang, Huai; Liu, GuangLong; Xiong, Jie; Yuan, DongXia; Feng, LiFang; Miao, Wei

    2015-03-01

    The reuse of dichlorodiphenyltrichloroethane (DDT) as an indoor residual spray was permitted by the World Health Organization in 2007, and approximately 14 countries still use DDT to control disease vectors. The extensive exposure of insects to DDT has resulted in the emergence of DDT resistance, especially in mosquitoes, and the mechanism for this resistance in mosquitoes has been widely reported. Spraying can also introduce DDT directly into surface water, and DDT can subsequently accumulate in microorganisms, but the mechanism for the resistance to DDT degradation in microorganisms is unclear. Using whole-genome microarray analysis, we detected an abcb15 gene that was up-regulated in a specific manner by DDT treatment in T. thermophile. The deduced ABCB15 peptide sequence had two transmembrane domains (TMDs) and two nucleotide-binding domains (NBDs) to form the structure TMD-NBD-TMD-NBD, and each NBD contained three conserved motifs: Walker-A, C-loop, and Walker-B, which indicated the T. thermophila abcb15 was a typical ABC transporter gene. The expression of ABCB15 fused with a C-terminal green fluorescent protein was found to be on the periphery of the cell, suggesting that ABCB15 was a membrane pump protein. In addition, cells with abcb15 partially knocked down (abcb15-KD) grew slower than wild-type cells in the presence of 256 mg L(-1) DDT, indicating the tolerance of abcb15-KD strain to DDT exposure was decreased. Thus, we suggest that in Tetrahymena, the membrane pump protein encoded by ABCT gene abcb15 can enhance the tolerance to DDT and protect cells from this exogenous toxin by efficiently pumping it to the extracellular space. PMID:25260902

  14. Cholesterol-loaded cyclodextrin enhances osmotic tolerance and inhibits the acrosome reaction in rabbit spermatozoa.

    PubMed

    Aksoy, Melih; Akman, Orhan; Lehimcioğlu, Necdet Cankat; Erdem, Hüseyin

    2010-07-01

    The effects of cholesterol-loaded cyclodextrin (CLC) treatment on the osmotic tolerance and ability to undergo the acrosome reaction of rabbit spermatozoa, with an unusually high cholesterol/phospholipid ratio in plasma membranes, were examined in two successive experiments. In the first experiment, CLC-pretreated and untreated sperm cells were exposed for 15min to one of five fructose solutions, adjusted to 20, 80, 290, 500 or 1500mOsm/L. After the anisoosmotic challenge, the integrity of sperm membranes in the CLC-supplemented (at a dose level of 3mg/120x10(6)spermatozoa) and control groups was estimated by a modified hypoosmotic swelling test (HOST) associated with a supravital eosin staining test (HE-test). In the second part of the study, the influence of cholesterol supplementation on the acrosome reaction of sperm cells stimulated by either calcium ionophore A23187 (CI) or lysophosphatidylcholine (LPC) was evaluated. CLC pretreatment increased viable and live-HOST-responsive sperm rates (P<0.01) after incubation in anisoosmotic solutions varying from 80 to 1500mOsm/L. However, CLC supplementation did not influence the percentage of HOST-responsive sperm cells (P>0.05). A significant interaction was determined between CLC pretreatment and the level of osmotic pressure in maintaining the functional and physical integrities of sperm membranes undergoing osmotic challenges. Both CI and LPC successfully induced the acrosome reaction in rabbit spermatozoa (P<0.001). Compared with CI, LPC was more effective (P<0.0001). CLC pretreatment resulted in a significant reduction (P<0.01) in the percentage of acrosome reacted sperm cells irrespective of the inducing agent, either CI or LPC. In conclusion, CLC treatment enhanced the anisoosmotic tolerance of rabbit spermatozoa and reduced their ability to undergo the acrosome reaction after stimulation by CI or LPC. PMID:20304567

  15. Heterologous Overexpression of Poplar SnRK2 Genes Enhanced Salt Stress Tolerance in Arabidopsis thaliana

    PubMed Central

    Song, Xueqing; Yu, Xiang; Hori, Chiaki; Demura, Taku; Ohtani, Misato; Zhuge, Qiang

    2016-01-01

    Subfamily 2 of SNF1-related protein kinase (SnRK2) plays important roles in plant abiotic stress responses as a global positive regulator of abscisic acid signaling. In the genome of the model tree Populus trichocarpa, 12 SnRK2 genes have been identified, and some are upregulated by abiotic stresses. In this study, we heterologously overexpressed the PtSnRK2 genes in Arabidopsis thaliana and found that overexpression of PtSnRK2.5 and PtSnRK2.7 genes enhanced stress tolerance. In the PtSnRK2.5 and PtSnRK2.7 overexpressors, chlorophyll content, and root elongation were maintained under salt stress conditions, leading to higher survival rates under salt stress compared with those in the wild type. Transcriptomic analysis revealed that PtSnRK2.7 overexpression affected stress-related metabolic genes, including lipid metabolism and flavonoid metabolism, even under normal growth conditions. However, the stress response genes reported to be upregulated in Arabidopsis SRK2C/SnRK2.6 and wheat SnRK2.8 overexpressors were not changed by PtSnRK2.7 overexpression. Furthermore, PtSnRK2.7 overexpression widely and largely influenced the transcriptome in response to salt stress; genes related to transport activity, including anion transport-related genes, were characteristically upregulated, and a variety of metabolic genes were specifically downregulated. We also found that the salt stress response genes were greatly upregulated in the PtSnRK2.7 overexpressor. Taken together, poplar subclass 2 PtSnRK2 genes can modulate salt stress tolerance in Arabidopsis, through the activation of cellular signaling pathways in a different manner from that by herbal subclass 2 SnRK2 genes. PMID:27242819

  16. Enhanced glucose tolerance in pancreatic-derived factor (PANDER) knockout C57BL/6 mice.

    PubMed

    Moak, Shari L; Dougan, Grace C; MarElia, Catherine B; Danse, Whitney A; Fernandez, Amanda M; Kuehl, Melanie N; Athanason, Mark G; Burkhardt, Brant R

    2014-11-01

    Pancreatic-derived factor (PANDER; also known as FAM3B) is a uniquely structured protein strongly expressed within and secreted from the endocrine pancreas. PANDER has been hypothesized to regulate fasting and fed glucose homeostasis, hepatic lipogenesis and insulin signaling, and to serve a potential role in the onset or progression of type 2 diabetes (T2D). Despite having potentially pivotal pleiotropic roles in glycemic regulation and T2D, there has been limited generation of stable animal models for the investigation of PANDER function, and there are no models on well-established genetic murine backgrounds for T2D. Our aim was to generate an enhanced murine model to further elucidate the biological function of PANDER. Therefore, a pure-bred PANDER knockout C57BL/6 (PANKO-C57) model was created and phenotypically characterized with respect to glycemic regulation and hepatic insulin signaling. The PANKO-C57 model exhibited an enhanced metabolic phenotype, particularly with regard to enhanced glucose tolerance. Male PANKO-C57 mice displayed decreased fasting plasma insulin and C-peptide levels, whereas leptin levels were increased as compared with matched C57BL/6J wild-type mice. Despite similar peripheral insulin sensitivity between both groups, hepatic insulin signaling was significantly increased during fasting conditions, as demonstrated by increased phosphorylation of hepatic PKB/Akt and AMPK, along with mature SREBP-1 expression. Insulin stimulation of PANKO-C57 mice resulted in increased hepatic triglyceride and glycogen content as compared with wild-type C57BL/6 mice. In summary, the PANKO-C57 mouse represents a suitable model for the investigation of PANDER in multiple metabolic states and provides an additional tool to elucidate the biological function and potential role in T2D. PMID:25217499

  17. Enhanced glucose tolerance in pancreatic-derived factor (PANDER) knockout C57BL/6 mice

    PubMed Central

    Moak, Shari L.; Dougan, Grace C.; MarElia, Catherine B.; Danse, Whitney A.; Fernandez, Amanda M.; Kuehl, Melanie N.; Athanason, Mark G.; Burkhardt, Brant R.

    2014-01-01

    Pancreatic-derived factor (PANDER; also known as FAM3B) is a uniquely structured protein strongly expressed within and secreted from the endocrine pancreas. PANDER has been hypothesized to regulate fasting and fed glucose homeostasis, hepatic lipogenesis and insulin signaling, and to serve a potential role in the onset or progression of type 2 diabetes (T2D). Despite having potentially pivotal pleiotropic roles in glycemic regulation and T2D, there has been limited generation of stable animal models for the investigation of PANDER function, and there are no models on well-established genetic murine backgrounds for T2D. Our aim was to generate an enhanced murine model to further elucidate the biological function of PANDER. Therefore, a pure-bred PANDER knockout C57BL/6 (PANKO-C57) model was created and phenotypically characterized with respect to glycemic regulation and hepatic insulin signaling. The PANKO-C57 model exhibited an enhanced metabolic phenotype, particularly with regard to enhanced glucose tolerance. Male PANKO-C57 mice displayed decreased fasting plasma insulin and C-peptide levels, whereas leptin levels were increased as compared with matched C57BL/6J wild-type mice. Despite similar peripheral insulin sensitivity between both groups, hepatic insulin signaling was significantly increased during fasting conditions, as demonstrated by increased phosphorylation of hepatic PKB/Akt and AMPK, along with mature SREBP-1 expression. Insulin stimulation of PANKO-C57 mice resulted in increased hepatic triglyceride and glycogen content as compared with wild-type C57BL/6 mice. In summary, the PANKO-C57 mouse represents a suitable model for the investigation of PANDER in multiple metabolic states and provides an additional tool to elucidate the biological function and potential role in T2D. PMID:25217499

  18. Ambient temperature enhanced freezing tolerance of Chrysanthemum dichrum CdICE1 Arabidopsis via miR398

    PubMed Central

    2013-01-01

    Background ICE (Inducer of CBF Expression) family genes play an important role in the regulation of cold tolerance pathways. In an earlier study, we isolated the gene CdICE1 from Chrysanthemum dichrum and demonstrated that freezing tolerance was enhanced by CdICE1 overexpression. Therefore, we sought to determine the mechanism by which ICE1 family genes participate in freezing tolerance. Results Using EMSA (Electrophoretic Mobility Shift Assay) and yeast one-hybrid assays, we confirmed that CdICE1 binds specifically to the MYC element in the CdDREBa promoter and activates transcription. In addition, overexpression of CdICE1 enhanced Arabidopsis freezing tolerance after transition from 23°C to 4°C or 16°C. We found that after acclimation to 4°C, CdICE1, like Arabidopsis AtICE1, promoted expression of CBFs (CRT/DRE Binding Factor) and their genes downstream involved in freezing tolerance, including COR15a (Cold-Regulated 15a), COR6.6, and RD29a (Responsive to Dessication 29a). Interestingly, we observed that CdICE1-overexpressing plants experienced significant reduction in miR398. In addition, its target genes CSD1 (Copper/zinc Superoxide Dismutase 1) and CSD2 showed inducible expression under acclimation at 16°C, indicating that the miR398-CSD pathway was involved in the induction of freezing tolerance. Conclusions Our data indicate that CdICE1-mediated freezing tolerance occurs via different pathways, involving either CBF or miR398, under acclimation at two different temperatures. PMID:24350981

  19. The AaDREB1 Transcription Factor from the Cold-Tolerant Plant Adonis amurensis Enhances Abiotic Stress Tolerance in Transgenic Plant

    PubMed Central

    Zong, Jun-Mei; Li, Xiao-Wei; Zhou, Yuan-Hang; Wang, Fa-Wei; Wang, Nan; Dong, Yuan-Yuan; Yuan, Yan-Xi; Chen, Huan; Liu, Xiu-Ming; Yao, Na; Li, Hai-Yan

    2016-01-01

    Dehydration-responsive element binding (DREB) transcription factors (TFs) play important roles in the regulation of plant resistance to environmental stresses and can specifically bind to dehydration-responsive element/C-repeat element (DRE/CRT) proteins (G/ACCGAC) and activate expression of many stress-inducible genes. Here, we cloned and characterized a novel gene (AaDREB1) encoding the DREB1 transcription factor from the cold-tolerant plant Adonis amurensis. Quantitative real-time (qRT)-PCR results indicated that AaDREB1 expression was induced by salt, drought, cold stress, and abscisic acid application. A yeast one-hybrid assay demonstrated that AaDREB1 encodes a transcription activator and specifically binds to DRE/CRT. Furthermore, transgenic Arabidopsis and rice harboring AaDREB1 showed enhanced tolerance to salt, drought, and low temperature. These results indicated that AaDREB1 might be useful in genetic engineering to improve plant stress tolerance. PMID:27110776

  20. The AaDREB1 Transcription Factor from the Cold-Tolerant Plant Adonis amurensis Enhances Abiotic Stress Tolerance in Transgenic Plant.

    PubMed

    Zong, Jun-Mei; Li, Xiao-Wei; Zhou, Yuan-Hang; Wang, Fa-Wei; Wang, Nan; Dong, Yuan-Yuan; Yuan, Yan-Xi; Chen, Huan; Liu, Xiu-Ming; Yao, Na; Li, Hai-Yan

    2016-01-01

    Dehydration-responsive element binding (DREB) transcription factors (TFs) play important roles in the regulation of plant resistance to environmental stresses and can specifically bind to dehydration-responsive element/C-repeat element (DRE/CRT) proteins (G/ACCGAC) and activate expression of many stress-inducible genes. Here, we cloned and characterized a novel gene (AaDREB1) encoding the DREB1 transcription factor from the cold-tolerant plant Adonis amurensis. Quantitative real-time (qRT)-PCR results indicated that AaDREB1 expression was induced by salt, drought, cold stress, and abscisic acid application. A yeast one-hybrid assay demonstrated that AaDREB1 encodes a transcription activator and specifically binds to DRE/CRT. Furthermore, transgenic Arabidopsis and rice harboring AaDREB1 showed enhanced tolerance to salt, drought, and low temperature. These results indicated that AaDREB1 might be useful in genetic engineering to improve plant stress tolerance. PMID:27110776

  1. The enhanced drought tolerance of rice plants under ammonium is related to aquaporin (AQP).

    PubMed

    Ding, Lei; Gao, Cuimin; Li, Yingrui; Li, Yong; Zhu, Yiyong; Xu, Guohua; Shen, Qirong; Kaldenhoff, Ralf; Kai, Lei; Guo, Shiwei

    2015-05-01

    Previously, we demonstrated that drought resistance in rice seedlings was increased by ammonium (NH4(+)) treatment, but not by nitrate (NO3(-)) treatment, and that the change was associated with root development. To study the effects of different forms of nitrogen on water uptake and root growth under drought conditions, we subjected two rice cultivars (cv. 'Shanyou 63' hybrid indica and cv. 'Yangdao 6' indica, China) to polyethylene glycol-induced drought stress in a glasshouse using hydroponic culture. Under drought conditions, NH4(+) significantly stimulated root growth compared to NO3(-), as indicated by the root length, surface area, volume, and numbers of lateral roots and root tips. Drought stress decreased the root elongation rate in both cultivars when they were supplied with NO3(-), while the rate was unaffected in the presence of NH4(+). Drought stress significantly increased root protoplast water permeability, root hydraulic conductivity, and the expression of root aquaporin (AQP) plasma intrinsic protein (PIP) genes in rice plants supplied with NH4(+); these changes were not observed in plants supplied with NO3(-). Additionally, ethylene, which is involved in the regulation of root growth, accumulated in rice roots supplied with NO3(-) under conditions of drought stress. We conclude that the increase in AQP expression and/or activity enhanced the root water uptake ability and the drought tolerance of rice plants supplied with NH4(+). PMID:25804805

  2. MpAsr encodes an intrinsically unstructured protein and enhances osmotic tolerance in transgenic Arabidopsis.

    PubMed

    Dai, Jin-Ran; Liu, Bing; Feng, Dong-Ru; Liu, Hai-yan; He, Yan-ming; Qi, Kang-biao; Wang, Hong-Bin; Wang, Jin-Fa

    2011-07-01

    Abscisic acid-, stress- and ripening (ASR) -induced proteins are plant-specific proteins whose expression is up-regulated under abiotic stresses or during fruit ripening. In this study, we characterized an ASR protein from plantain to explore its physiological roles under osmotic stress. The expression pattern of MpAsr gene shows that MpAsr gene changed little at the mRNA level, while the MpASR protein accumulates under osmotic treatment. Through bioinformatic-based predictions, circular dichroism spectrometry, and proteolysis and heat-stability assays, we determined that the MpASR protein is an intrinsically unstructured protein in solution. We demonstrated that the hydrophilic MpASR protein could protect L: -lactate dehydrogenase (L: -LDH) from cold-induced aggregation. Furthermore, heterologous expression of MpAsr in Escherichia coli and Arabidopsis enhanced the tolerance of transformants to osmotic stress. Transgenic 35S::MpAsr Arabidopsis seeds had a higher germination frequency than wild-type seeds under unfavorable conditions. At the physiological level, 35S::MpAsr Arabidopsis showed increased soluble sugars and decreased cell membrane damage under osmotic stress. Thus, our results suggest that the MpASR protein may act as an osmoprotectant and water-retaining molecule to help cell adjustment to water deficit caused by osmotic stress. PMID:21327389

  3. Overexpression of Late Embryogenesis Abundant 14 enhances Arabidopsis salt stress tolerance.

    PubMed

    Jia, Fengjuan; Qi, Shengdong; Li, Hui; Liu, Pu; Li, Pengcheng; Wu, Changai; Zheng, Chengchao; Huang, Jinguang

    2014-11-28

    Late embryogenesis abundant (LEA) proteins are implicated in various abiotic stresses in higher plants. In this study, we identified a LEA protein from Arabidopsis thaliana, AtLEA14, which was ubiquitously expressed in different tissues and remarkably induced with increased duration of salt treatment. Subcellular distribution analysis demonstrated that AtLEA14 was mainly localized in the cytoplasm. Transgenic Arabidopsis and yeast overexpressing AtLEA14 all exhibited enhanced tolerance to high salinity. The transcripts of salt stress-responsive marker genes (COR15a, KIN1, RD29B and ERD10) were overactivated in AtLEA14 overexpressing lines compared with those in wild type plants under normal or salt stress conditions. In vivo and in vitro analysis showed that AtLEA14 could effectively stabilize AtPP2-B11, an important E3 ligase. These results suggested that AtLEA14 had important protective functions under salt stress conditions in Arabidopsis. PMID:25450686

  4. Knock-out of Arabidopsis AtNHX4 gene enhances tolerance to salt stress

    SciTech Connect

    Li, Hong-Tao; Liu, Hua; Gao, Xiao-Shu; Zhang, Hongxia

    2009-05-08

    AtNHX4 belongs to the monovalent cation:proton antiporter-1 (CPA1) family in Arabidopsis. Several members of this family have been shown to be critical for plant responses to abiotic stress, but little is known on the biological functions of AtNHX4. Here, we provide the evidence that AtNHX4 plays important roles in Arabidopsis responses to salt stress. Expression of AtNHX4 was responsive to salt stress and abscisic acid. Experiments with CFP-AtNHX4 fusion protein indicated that AtNHX4 is vacuolar localized. The nhx4 mutant showed enhanced tolerance to salt stress, and lower Na{sup +} content under high NaCl stress compared with wild-type plants. Furthermore, heterologous expression of AtNHX4 in Escherichia coli BL21 rendered the transformants hypersensitive to NaCl. Deletion of the hydrophilic C-terminus of AtNHX4 dramatically increased the hypersensitivity of transformants, indicating that AtNHX4 may function in Na{sup +} homeostasis in plant cell, and its C-terminus plays a role in regulating the AtNHX4 activity.

  5. Selection of cowpea progenies with enhanced drought-tolerance traits using principal component analysis.

    PubMed

    Sousa, C C; Damasceno-Silva, K J; Bastos, E A; Rocha, M M

    2015-01-01

    Vigna unguiculata (L.) Walp (cowpea) is a food crop with high nutritional value that is cultivated throughout tropical and subtropical regions of the world. The main constraint on high productivity of cowpea is water deficit, caused by the long periods of drought that occur in these regions. The aim of the present study was to select elite cowpea genotypes with enhanced drought tolerance, by applying principal component analysis to 219 first-cycle progenies obtained in a recurrent selection program. The experimental design comprised a simple 15 x 15 lattice with 450 plots, each of two rows of 10 plants. Plants were grown under water-deficit conditions by applying a water depth of 205 mm representing one-half of that required by cowpea. Variables assessed were flowering, maturation, pod length, number and mass of beans/pod, mass of 100 beans, and productivity/plot. Ten elite cowpea genotypes were selected, in which principal components 1 and 2 encompassed variables related to yield (pod length, beans/pod, and productivity/plot) and life precocity (flowering and maturation), respectively. PMID:26662390

  6. 24-Epibrassinoslide enhances plant tolerance to stress from low temperatures and poor light intensities in tomato (Lycopersicon esculentum Mill.).

    PubMed

    Cui, Lirong; Zou, Zhirong; Zhang, Jing; Zhao, Yanyan; Yan, Fei

    2016-01-01

    Brassinosteroids (Brs) are a newly recognized group of active steroidal hormones that occur at low concentrations in all plant parts and one of the active and stable forms is 24-epibrassinolide (EBR). We investigated the effect of EBR on tomato (Lycopersicon esculentum Mill.) and its mechanism when seedlings were exposed to low temperature and poor light stress conditions. Leaves of stress-tolerant 'Zhongza9' and stress-sensitive 'Zhongshu4' cultivars were pre-treated with spray solutions containing either 0.1 μM EBR or no EBR (control). The plants were then transferred to chambers where they were exposed to low temperatures of 12 °C/6 °C (day/night) under a low light (LL) level of 80 μmol · m(-2) · s(-1). Exogenous application of EBR significantly increased the antioxidant activity of superoxide dismutase, catalase and peroxidase, and decreased the rate of O2 · (-) formation and H2O2 and malondialdehyde contents. Additionally, the ATP synthase β subunit content was increased by exogenous hormone application. Based on these results, we conclude that exogenous EBR can elicit synergism between the antioxidant enzyme systems and the ATP synthase β subunit so that scavenging of reactive oxygen species becomes more efficient. These activities enable plants to cope better under combined low temperature and poor light stresses. PMID:26337714

  7. Metabolic Depression in Cunner (Tautogolabrus adspersus) Is Influenced by Ontogeny, and Enhances Thermal Tolerance

    PubMed Central

    Nash, Gordon W.; Gamperl, A. Kurt

    2014-01-01

    To examine the effect of ontogeny on metabolic depression in the cunner (Tautogolabrus adspersus), and to understand how ontogeny and the ability to metabolically depress influence this species' upper thermal tolerance: 1) the metabolic rate of 9°C-acclimated cunner of three size classes [0.2–0.5 g, young of the year (YOY); 3–6 g, small; and 80–120 g, large (adult)] was measured during a 2°C per day decrease in temperature; and 2) the metabolic response of the same three size classes of cunner to an acute thermal challenge [2°C h−1 from 10°C until Critical Thermal Maximum, CTMax] was examined, and compared to that of the Atlantic cod (Gadus morhua). The onset-temperature for metabolic depression in cunner increased with body size, i.e. from 5°C in YOY cunner to 7°C in adults. In contrast, the extent of metabolic depression was ∼80% (Q10 = ∼15) for YOY fish, ∼65% (Q10 = ∼8) for small fish and ∼55% (Q10 = ∼5) for adults, and this resulted in the metabolic scaling exponent (b) gradually increasing from 0.84 to 0.92 between 9°C to 1°C. All size classes of cunner had significantly (approximately 60%) lower routine metabolic rates at 10°C than Atlantic cod. However, there was no species' difference in the temperature-induced maximum metabolic rate, and this resulted in factorial metabolic scope values that were more than two-fold greater for cunner, and CTMax values that were 6–9°C higher (∼21 vs. 28°C). These results: 1) show that ontogeny influences the temperature of initiation and the extent of metabolic depression in cunner, but not O2 consumption when in a hypometabolic state; and 2) suggest that the evolution of cold-induced metabolic depression in this northern wrasse species has not resulted in a trade-off with upper thermal tolerance, but instead, an enhancement of this species' metabolic plasticity. PMID:25514755

  8. Novel NAC Transcription Factor TaNAC67 Confers Enhanced Multi-Abiotic Stress Tolerances in Arabidopsis

    PubMed Central

    Mao, Xinguo; Chen, Shuangshuang; Li, Ang; Zhai, Chaochao; Jing, Ruilian

    2014-01-01

    Abiotic stresses are major environmental factors that affect agricultural productivity worldwide. NAC transcription factors play pivotal roles in abiotic stress signaling in plants. As a staple crop, wheat production is severely constrained by abiotic stresses whereas only a few NAC transcription factors have been characterized functionally. To promote the application of NAC genes in wheat improvement by biotechnology, a novel NAC gene designated TaNAC67 was characterized in common wheat. To determine its role, transgenic Arabidopsis overexpressing TaNAC67-GFP controlled by the CaMV-35S promoter was generated and subjected to various abiotic stresses for morphological and physiological assays. Gene expression showed that TaNAC67 was involved in response to drought, salt, cold and ABA treatments. Localization assays revealed that TaNAC67 localized in the nucleus. Morphological analysis indicated the transgenics had enhanced tolerances to drought, salt and freezing stresses, simultaneously supported by enhanced expression of multiple abiotic stress responsive genes and improved physiological traits, including strengthened cell membrane stability, retention of higher chlorophyll contents and Na+ efflux rates, improved photosynthetic potential, and enhanced water retention capability. Overexpression of TaNAC67 resulted in pronounced enhanced tolerances to drought, salt and freezing stresses, therefore it has potential for utilization in transgenic breeding to improve abiotic stress tolerance in crops. PMID:24427285

  9. Inspiratory muscle training enhances pulmonary O(2) uptake kinetics and high-intensity exercise tolerance in humans.

    PubMed

    Bailey, Stephen J; Romer, Lee M; Kelly, James; Wilkerson, Daryl P; DiMenna, Fred J; Jones, Andrew M

    2010-08-01

    Fatigue of the respiratory muscles during intense exercise might compromise leg blood flow, thereby constraining oxygen uptake (Vo(2)) and limiting exercise tolerance. We tested the hypothesis that inspiratory muscle training (IMT) would reduce inspiratory muscle fatigue, speed Vo(2) kinetics and enhance exercise tolerance. Sixteen recreationally active subjects (mean + or - SD, age 22 + or - 4 yr) were randomly assigned to receive 4 wk of either pressure threshold IMT [30 breaths twice daily at approximately 50% of maximum inspiratory pressure (MIP)] or sham treatment (60 breaths once daily at approximately 15% of MIP). The subjects completed moderate-, severe- and maximal-intensity "step" exercise transitions on a cycle ergometer before (Pre) and after (Post) the 4-wk intervention period for determination of Vo(2) kinetics and exercise tolerance. There were no significant changes in the physiological variables of interest after Sham. After IMT, baseline MIP was significantly increased (Pre vs. Post: 155 + or - 22 vs. 181 + or - 21 cmH(2)O; P < 0.001), and the degree of inspiratory muscle fatigue was reduced after severe- and maximal-intensity exercise. During severe exercise, the Vo(2) slow component was reduced (Pre vs. Post: 0.60 + or - 0.20 vs. 0.53 + or - 0.24 l/min; P < 0.05) and exercise tolerance was enhanced (Pre vs. Post: 765 + or - 249 vs. 1,061 + or - 304 s; P < 0.01). Similarly, during maximal exercise, the Vo(2) slow component was reduced (Pre vs. Post: 0.28 + or - 0.14 vs. 0.18 + or - 0.07 l/min; P < 0.05) and exercise tolerance was enhanced (Pre vs. Post: 177 + or - 24 vs. 208 + or - 37 s; P < 0.01). Four weeks of IMT, which reduced inspiratory muscle fatigue, resulted in a reduced Vo(2) slow-component amplitude and an improved exercise tolerance during severe- and maximal-intensity exercise. The results indicate that the enhanced exercise tolerance observed after IMT might be related, at least in part, to improved Vo(2) dynamics, presumably as a

  10. Function of wheat Ta-UnP gene in enhancing salt tolerance in transgenic Arabidopsis and rice.

    PubMed

    Liang, Wenji; Cui, Weina; Ma, Xiaoli; Wang, Gang; Huang, Zhanjing

    2014-07-18

    Based on microarray analysis results of the salt tolerant wheat mutant, we identified and cloned an unknown salt-induced gene Ta-UnP (Triticum aestivum unknown protein). Quantitative PCR results revealed that Ta-UnP expression was induced not only by salt but also by polyethylene glycol, abscisic acid, and other environmental stress factors. Under salt stress, transgenic Arabidopsis plants that overexpressed Ta-UnP showed superior physiological properties (content of proline, soluble sugar, MDA, and chlorophyll) compared with the control. Subcellular localization demonstrated that Ta-UnP was mainly localized on the cell membrane. The expressions of nine salt tolerance-related genes of Arabidopsis in Ta-UnP-overexpressed Arabidopsis were analyzed via qPCR, and the results revealed that the expressions of SOS2, SOS3, RD29B, and P5CS were significantly up-regulated, whereas the other five genes only slightly changed. The results of the salt tolerance analysis indicated that Ta-UnP can enhance the salt tolerance of transgenic rice plants, and RNAi transgenic rice plants became highly susceptible to salt stress. The results from this study indicate that this novel Ta-UnP may be useful in improving of plant tolerance to salt stress. PMID:24953696

  11. Over-expression of PsGPD, a mushroom glyceraldehyde-3-phosphate dehydrogenase gene, enhances salt tolerance in rice plants.

    PubMed

    Cho, Jung-Il; Lim, Hye-Min; Siddiqui, Zamin Shaheed; Park, Sung-Han; Kim, A-Ram; Kwon, Taek-Ryoun; Lee, Seong-Kon; Park, Soo-Chul; Jeong, Mi-Jeong; Lee, Gang-Seob

    2014-08-01

    Transgenic potatoes expressing glyceraldehyde-3-phosphate dehydrogenase (GPD), isolated from the oyster mushroom, Pleurotus sajor-caju, had increased tolerance to salt stress (Jeong et al. Biochem Biophys Res Commun 278:192-196, 2000). To examine the physiological mechanisms enhancing salt tolerance in GPD-transgenic rice plants, the salt tolerance of five GPD transgenic rice lines (T1-T5) derived from Dongjin rice cultivar were evaluated in a fixed 150 mM saline environment in comparison to two known wild-type rice cultivars, Dongjin (salt sensitive) and Pokali (salt tolerant). Transgenic lines, T2, T3, and T5, had a substantial increase in biomass and relative water content compared to Dongjin. Stomatal conductance and osmotic potential were higher in the GPD transgenic lines and were similar to those in Pokali. The results are discussed based on the comparative physiological response of GPD transgenic lines with those of the salt-sensitive and salt-tolerant rice cultivars. PMID:24737077

  12. Genetic enhancement of cold tolerance to overcome a major limitation in sorghum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Early season cold tolerance during stand establishment at cool soil temperature of 54ºF to 59ºF (12 ºC to 15ºC) is a key agronomic trait for warm season cereal crops such as sorghum. Sorghum (Sorghum bicolor L. [Moench]), lacks cold tolerance and is adversely affected by cool temperatures during ger...

  13. Overexpression of OsEm1 encoding a group I LEA protein confers enhanced drought tolerance in rice.

    PubMed

    Yu, Jing; Lai, Yongmin; Wu, Xi; Wu, Gang; Guo, Changkui

    2016-09-16

    Drought is the greatest threat for crops, including rice. In an effort to identify rice genes responsible for drought tolerance, a drought-responsive gene OsEm1 encoding a group I LEA protein, was chosen for this study. OsEm1 was shown at vegetative stages to be responsive to various abiotic stresses, including drought, salt, cold and the hormone ABA. In this study, we generated OsEm1-overexpressing rice plants to explore the function of OsEm1 under drought conditions. Overexpression of OsEm1 increases ABA sensitivity and enhances osmotic tolerance in rice. Compared with wild type, the OsEm1-overexpressing rice plants showed enhanced plant survival ratio at the vegetative stage; moreover, over expression of OsEm1 in rice increased the expression of other LEA genes, including RAB16A, RAB16C, RAB21, and LEA3, likely protecting organ integrity against harsh environments. Interestingly, the elevated level of OsEm1 had no different phenotype compared with wild type under normal condition. Our findings suggest that OsEm1 is a positive regulator of drought tolerance and is potentially promising for engineering drought tolerance in rice. PMID:27524243

  14. Plant Growth Promoting Rhizobacteria and Silicon Synergistically Enhance Salinity Tolerance of Mung Bean.

    PubMed

    Mahmood, Sajid; Daur, Ihsanullah; Al-Solaimani, Samir G; Ahmad, Shakeel; Madkour, Mohamed H; Yasir, Muhammad; Hirt, Heribert; Ali, Shawkat; Ali, Zahir

    2016-01-01

    The present study explored the eco-friendly approach of utilizing plant-growth-promoting rhizobacteria (PGPR) inoculation and foliar application of silicon (Si) to improve the physiology, growth, and yield of mung bean under saline conditions. We isolated 18 promising PGPR from natural saline soil in Saudi Arabia, and screened them for plant-growth-promoting activities. Two effective strains were selected from the screening trial, and were identified as Enterobacter cloacae and Bacillus drentensis using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and 16S rRNA gene sequencing techniques, respectively. Subsequently, in a 2-year mung bean field trial, using a randomized complete block design with a split-split plot arrangement, we evaluated the two PGPR strains and two Si levels (1 and 2 kg ha(-1)), in comparison with control treatments, under three different saline irrigation conditions (3.12, 5.46, and 7.81 dS m(-1)). The results indicated that salt stress substantially reduced stomatal conductance, transpiration rate, relative water content (RWC), total chlorophyll content, chlorophyll a, chlorophyll b, carotenoid content, plant height, leaf area, dry biomass, seed yield, and salt tolerance index. The PGPR strains and Si levels independently improved all the aforementioned parameters. Furthermore, the combined application of the B. drentensis strain with 2 kg Si ha(-1) resulted in the greatest enhancement of mung bean physiology, growth, and yield. Overall, the results of this study provide important information for the benefit of the agricultural industry. PMID:27379151

  15. Root ABA Accumulation Enhances Rice Seedling Drought Tolerance under Ammonium Supply: Interaction with Aquaporins

    PubMed Central

    Ding, Lei; Li, Yingrui; Wang, Ying; Gao, Limin; Wang, Min; Chaumont, François; Shen, Qirong; Guo, Shiwei

    2016-01-01

    In previous studies, we demonstrated that ammonium nutrition enhances the drought tolerance of rice seedlings compared to nitrate nutrition and contributes to a higher root water uptake ability. It remains unclear why rice seedlings maintain a higher water uptake ability when supplied with ammonium under drought stress. Here, we focused on the effects of nitrogen form and drought stress on root abscisic acid (ABA) concentration and aquaporin expression using hydroponics experiments and stimulating drought stress with 10% PEG6000. Drought stress decreased the leaf photosynthetic rate and stomatal conductivity and increased the leaf temperature of plants supplied with either ammonium or nitrate, but especially under nitrate supply. After 4 h of PEG treatment, the root protoplast water permeability and the expression of root PIP and TIP genes decreased in plants supplied with ammonium or nitrate. After 24 h of PEG treatment, the root hydraulic conductivity, the protoplast water permeability, and the expression of some aquaporin genes increased in plants supplied with ammonium compared to those under non-PEG treatment. Root ABA accumulation was induced by 24 h of PEG treatment, especially in plants supplied with ammonium. The addition of exogenous ABA decreased the expression of PIP and TIP genes under non-PEG treatment but increased the expression of some of them under PEG treatment. We concluded that drought stress induced a down-regulation of aquaporin expression, which appeared earlier than did root ABA accumulation. With continued drought stress, aquaporin expression and activity increased due to root ABA accumulation in plants supplied with ammonium. PMID:27559341

  16. Plant Growth Promoting Rhizobacteria and Silicon Synergistically Enhance Salinity Tolerance of Mung Bean

    PubMed Central

    Mahmood, Sajid; Daur, Ihsanullah; Al-Solaimani, Samir G.; Ahmad, Shakeel; Madkour, Mohamed H.; Yasir, Muhammad; Hirt, Heribert; Ali, Shawkat; Ali, Zahir

    2016-01-01

    The present study explored the eco-friendly approach of utilizing plant-growth-promoting rhizobacteria (PGPR) inoculation and foliar application of silicon (Si) to improve the physiology, growth, and yield of mung bean under saline conditions. We isolated 18 promising PGPR from natural saline soil in Saudi Arabia, and screened them for plant-growth-promoting activities. Two effective strains were selected from the screening trial, and were identified as Enterobacter cloacae and Bacillus drentensis using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and 16S rRNA gene sequencing techniques, respectively. Subsequently, in a 2-year mung bean field trial, using a randomized complete block design with a split-split plot arrangement, we evaluated the two PGPR strains and two Si levels (1 and 2 kg ha−1), in comparison with control treatments, under three different saline irrigation conditions (3.12, 5.46, and 7.81 dS m−1). The results indicated that salt stress substantially reduced stomatal conductance, transpiration rate, relative water content (RWC), total chlorophyll content, chlorophyll a, chlorophyll b, carotenoid content, plant height, leaf area, dry biomass, seed yield, and salt tolerance index. The PGPR strains and Si levels independently improved all the aforementioned parameters. Furthermore, the combined application of the B. drentensis strain with 2 kg Si ha−1 resulted in the greatest enhancement of mung bean physiology, growth, and yield. Overall, the results of this study provide important information for the benefit of the agricultural industry. PMID:27379151

  17. Root ABA Accumulation Enhances Rice Seedling Drought Tolerance under Ammonium Supply: Interaction with Aquaporins.

    PubMed

    Ding, Lei; Li, Yingrui; Wang, Ying; Gao, Limin; Wang, Min; Chaumont, François; Shen, Qirong; Guo, Shiwei

    2016-01-01

    In previous studies, we demonstrated that ammonium nutrition enhances the drought tolerance of rice seedlings compared to nitrate nutrition and contributes to a higher root water uptake ability. It remains unclear why rice seedlings maintain a higher water uptake ability when supplied with ammonium under drought stress. Here, we focused on the effects of nitrogen form and drought stress on root abscisic acid (ABA) concentration and aquaporin expression using hydroponics experiments and stimulating drought stress with 10% PEG6000. Drought stress decreased the leaf photosynthetic rate and stomatal conductivity and increased the leaf temperature of plants supplied with either ammonium or nitrate, but especially under nitrate supply. After 4 h of PEG treatment, the root protoplast water permeability and the expression of root PIP and TIP genes decreased in plants supplied with ammonium or nitrate. After 24 h of PEG treatment, the root hydraulic conductivity, the protoplast water permeability, and the expression of some aquaporin genes increased in plants supplied with ammonium compared to those under non-PEG treatment. Root ABA accumulation was induced by 24 h of PEG treatment, especially in plants supplied with ammonium. The addition of exogenous ABA decreased the expression of PIP and TIP genes under non-PEG treatment but increased the expression of some of them under PEG treatment. We concluded that drought stress induced a down-regulation of aquaporin expression, which appeared earlier than did root ABA accumulation. With continued drought stress, aquaporin expression and activity increased due to root ABA accumulation in plants supplied with ammonium. PMID:27559341

  18. Improvement on the thermal stability and activity of plant cytosolic ascorbate peroxidase 1 by tailing hyper-acidic fusion partners.

    PubMed

    Zhang, Mengru; Gong, Ming; Yang, Yumei; Li, Xujuan; Wang, Haibo; Zou, Zhurong

    2015-04-01

    Cytosolic ascorbate peroxidase 1 (APX1) plays a crucial role in regulating the level of plant cellular reactive oxygen species and its thermolability is proposed to cause plant heat-susceptibility. Herein, several hyper-acidic fusion partners, such as the C-terminal peptide tails, were evaluated for their effects on the thermal stability and activity of APX1 from Jatropha curcas and Arabidopsis. The hyper-acidic fusion partners efficiently improved the thermostability and prevented thermal inactivation of APX1 in both plant species with an elevated heat tolerance of at least 2 °C. These hyper-acidified thermostable APX1 fusion variants are of considerable biotechnological potential and can provide a new route to enhance the heat tolerance of plant species especially of inherent thermo-sensitivity. PMID:25515798

  19. Dietary Fiber and Bacterial SCFA Enhance Oral Tolerance and Protect against Food Allergy through Diverse Cellular Pathways.

    PubMed

    Tan, Jian; McKenzie, Craig; Vuillermin, Peter J; Goverse, Gera; Vinuesa, Carola G; Mebius, Reina E; Macia, Laurence; Mackay, Charles R

    2016-06-21

    The incidence of food allergies in western countries has increased dramatically in recent decades. Tolerance to food antigens relies on mucosal CD103(+) dendritic cells (DCs), which promote differentiation of regulatory T (Treg) cells. We show that high-fiber feeding in mice improved oral tolerance and protected from food allergy. High-fiber feeding reshaped gut microbial ecology and increased the release of short-chain fatty acids (SCFAs), particularly acetate and butyrate. High-fiber feeding enhanced oral tolerance and protected against food allergy by enhancing retinal dehydrogenase activity in CD103(+) DC. This protection depended on vitamin A in the diet. This feeding regimen also boosted IgA production and enhanced T follicular helper and mucosal germinal center responses. Mice lacking GPR43 or GPR109A, receptors for SCFAs, showed exacerbated food allergy and fewer CD103(+) DCs. Dietary elements, including fiber and vitamin A, therefore regulate numerous protective pathways in the gastrointestinal tract, necessary for immune non-responsiveness to food antigens. PMID:27332875

  20. [A comparative evaluation of contact lens tolerance and the possibilities for its enhancement].

    PubMed

    Egorova, G B; Avetisov, S E; Churkina, M N; Rybakova, E G

    1990-01-01

    The paper analyses results after examination of 276 patients (495 eyes) with different types of rigid and soft contact lenses. A study of some ways for improvement of contact lens tolerance has shown that improvement of rigid contact lenses can be achieved both by perfection of their construction (in particular by using spherotoric rigid lenses) and with the help of gas-permeable materials (in particular, cellulase acetobutyrate). The improvement of soft lens tolerance can be achieved by reducing the thickness of the lens as well us by using highly hydrophilic gels. If the known methods for improvement of contact lens tolerance fail to be effective, medicamentous preparations (such as solcoseryl, taufon, emoxipin) can be used as a method of choice; their usage is justified in keratoconus of stages II-IV, when rigid lenses are a single kind of optic correction and their tolerance is lowered. PMID:2255483

  1. Overexpression of Arabidopsis phytochelatin synthase in tobacco plants enhances Cd(2+) tolerance and accumulation but not translocation to the shoot.

    PubMed

    Pomponi, Mirella; Censi, Vincenzo; Di Girolamo, Valentina; De Paolis, Angelo; di Toppi, Luigi Sanità; Aromolo, Rita; Costantino, Paolo; Cardarelli, Maura

    2006-01-01

    Phytochelatins (PCs) are metal binding peptides involved in heavy metal detoxification. To assess whether enhanced phytochelatin synthesis would increase heavy metal tolerance and accumulation in plants, we overexpressed the Arabidopsis phytochelatin synthase gene (AtPCS1) in the non-accumulator plant Nicotiana tabacum. Wild-type plants and plants harbouring the Agrobacterium rhizogenes rolB oncogene were transformed with a 35S AtPCS1 construct. Root cultures from rolB plants could be easily established and we demonstrated here that they represent a reliable system to study heavy metal tolerance. Cd(2+) tolerance in cultured rolB roots was increased as a result of overexpression of AtPCS1, and further enhanced when reduced glutathione (GSH, the substrate of PCS1) was added to the culture medium. Accordingly, HPLC analysis showed that total PC production in PCS1-overexpressing rolB roots was higher than in rolB roots in the presence of GSH. Overexpression of AtPCS1 in whole seedlings led to a twofold increase in Cd(2+) accumulation in the roots and shoots of both rolB and wild-type seedlings. Similarly, a significant increase in Cd(2+) accumulation linked to a higher production of PCs in both roots and shoots was observed in adult plants. However, the percentage of Cd(2+) translocated to the shoots of seedlings and adult overexpressing plants was unaffected. We conclude that the increase in Cd(2+) tolerance and accumulation of PCS1 overexpressing plants is directly related to the availability of GSH, while overexpression of phytochelatin synthase does not enhance long distance root-to-shoot Cd(2+) transport. PMID:16133212

  2. The Arabidopsis transcriptional regulator DPB3-1 enhances heat stress tolerance without growth retardation in rice.

    PubMed

    Sato, Hikaru; Todaka, Daisuke; Kudo, Madoka; Mizoi, Junya; Kidokoro, Satoshi; Zhao, Yu; Shinozaki, Kazuo; Yamaguchi-Shinozaki, Kazuko

    2016-08-01

    The enhancement of heat stress tolerance in crops is an important challenge for food security to facilitate adaptation to global warming. In Arabidopsis thaliana, the transcriptional regulator DNA polymerase II subunit B3-1 (DPB3-1)/nuclear factor Y subunit C10 (NF-YC10) has been reported as a positive regulator of Dehydration-responsive element binding protein 2A (DREB2A), and the overexpression of DPB3-1 enhances heat stress tolerance without growth retardation. Here, we show that DPB3-1 interacts with DREB2A homologues in rice and soya bean. Transactivation analyses with Arabidopsis and rice mesophyll protoplasts indicate that DPB3-1 and its rice homologue OsDPB3-2 function as positive regulators of DREB2A homologues. Overexpression of DPB3-1 did not affect plant growth or yield in rice under nonstress conditions. Moreover, DPB3-1-overexpressing rice showed enhanced heat stress tolerance. Microarray analysis revealed that many heat stress-inducible genes were up-regulated in DPB3-1-overexpressing rice under heat stress conditions. However, the overexpression of DPB3-1 using a constitutive promoter had almost no effect on the expression of these genes under nonstress conditions. This may be because DPB3-1 is a coactivator and thus lacks inherent transcriptional activity. We conclude that DPB3-1, a coactivator that functions specifically under abiotic stress conditions, could be utilized to increase heat stress tolerance in crops without negative effects on vegetative and reproductive growth. PMID:26841113

  3. Comprehensive transcript profiling of two grapevine rootstock genotypes contrasting in drought susceptibility links the phenylpropanoid pathway to enhanced tolerance

    PubMed Central

    Corso, Massimiliano; Vannozzi, Alessandro; Maza, Elie; Vitulo, Nicola; Meggio, Franco; Pitacco, Andrea; Telatin, Andrea; D’Angelo, Michela; Feltrin, Erika; Negri, Alfredo Simone; Prinsi, Bhakti; Valle, Giorgio; Ramina, Angelo; Bouzayen, Mondher; Bonghi, Claudio; Lucchin, Margherita

    2015-01-01

    In light of ongoing climate changes in wine-growing regions, the selection of drought-tolerant rootstocks is becoming a crucial factor for developing a sustainable viticulture. In this study, M4, a new rootstock genotype that shows tolerance to drought, was compared from a genomic and transcriptomic point of view with the less drought-tolerant genotype 101.14. The root and leaf transcriptome of both 101.14 and the M4 rootstock genotype was analysed, following exposure to progressive drought conditions. Multifactorial analyses indicated that stress treatment represents the main factor driving differential gene expression in roots, whereas in leaves the genotype is the prominent factor. Upon stress, M4 roots and leaves showed a higher induction of resveratrol and flavonoid biosynthetic genes, respectively. The higher expression of VvSTS genes in M4, confirmed by the accumulation of higher levels of resveratrol in M4 roots compared with 101.14, was coupled to an up-regulation of several VvWRKY transcription factors. Interestingly, VvSTS promoter analyses performed on both the resequenced genomes highlighted a significantly higher number of W-BOX elements in the tolerant genotype. It is proposed that the elevated synthesis of resveratrol in M4 roots upon water stress could enhance the plant’s ability to cope with the oxidative stress usually associated with water deficit. PMID:26038306

  4. Phase 1A Final Report for the AREVA Team Enhanced Accident Tolerant Fuels Concepts

    SciTech Connect

    Morrell, Mike E.

    2015-03-19

    In response to the Department of Energy (DOE) funded initiative to develop and deploy lead fuel assemblies (LFAs) of Enhanced Accident Tolerant Fuel (EATF) into a US reactor within 10 years, AREVA put together a team to develop promising technologies for improved fuel performance during off normal operations. This team consisted of the University of Florida (UF) and the University of Wisconsin (UW), Savannah River National Laboratory (SRNL), Duke Energy and Tennessee Valley Authority (TVA). This team brought broad experience and expertise to bear on EATF development. AREVA has been designing; manufacturing and testing nuclear fuel for over 50 years and is one of the 3 large international companies supplying fuel to the nuclear industry. The university and National Laboratory team members brought expertise in nuclear fuel concepts and materials development. Duke and TVA brought practical utility operating experience. This report documents the results from the initial “discovery phase” where the team explored options for EATF concepts that provide enhanced accident tolerance for both Design Basis (DB) and Beyond Design Basis Events (BDB). The main driver for the concepts under development were that they could be implemented in a 10 year time frame and be economically viable and acceptable to the nuclear fuel marketplace. The economics of fuel design make this DOE funded project very important to the nuclear industry. Even incremental changes to an existing fuel design can cost in the range of $100M to implement through to LFAs. If this money is invested evenly over 10 years then it can take the fuel vendor several decades after the start of the project to recover their initial investment and reach a breakeven point on the initial investment. Step or radical changes to a fuel assembly design can cost upwards of $500M and will take even longer for the fuel vendor to recover their investment. With the projected lifetimes of the current generation of nuclear power

  5. Synergistic enhancement of tolerance mechanisms in response to photoactivation of cationic tetra (N-methylpyridyl) porphyrins in tomato plantlets.

    PubMed

    Guillaumot, Damien; Issawi, Mohammad; Da Silva, Anne; Leroy-Lhez, Stephanie; Sol, Vincent; Riou, Catherine

    2016-03-01

    Antimicrobial photodynamic treatment (APDT) is largely used in medical domain and could be envisaged as a farming practice against crop pathogens such as bacteria and fungi that generate drops in agricultural yields. Thus, as a prerequisite for this potential application, we studied the effect of water-soluble anionic (TPPS and Zn-TPPS) and cationic (TMPyP and Zn-TMPyP) porphyrins tested on tomato (Solanum lycopersicum) plantlets grown in vitro under a 16 h photoperiod. First of all, under dark conditions, none of the four porphyrins inhibited germination and induced cytotoxic effects on tomato plantlets as etiolated development was not altered. The consequences of porphyrin long-term photoactivation (14 days) were thus studied on in vitro-grown tomato plantlets at phenotypic and molecular levels. Cationic porphyrins especially Zn-TMPyP were the most efficient photosensitizers and dramatically altered growth without killing plantlets. Indeed, tomato plantlets were rescued after cationic porphyrins treatment. To gain insight, the different molecular ways implied in the plantlet tolerance to photoactivated Zn-TMPyP, lipid peroxidation, antioxidative molecules (total thiols, proline, ascorbate), and ROS detoxification enzymes were evaluated. In parallel to an increase in lipid peroxidation and hydrogen peroxide production, antioxidative molecules and enzymes (guaiacol peroxidase, catalase, and superoxide dismutase) were up-regulated in root apparatus in response to photoactivated Zn-TMPyP. This study showed that tomato plantlets could overcome the pressure triggered by photoactivated cationic porphyrin by activating antioxidative molecule and enzyme arsenal and confining Zn-TMPyP into cell wall and/or apoplasm, suggesting that APDT directed against tomato pathogens could be envisaged in the future. PMID:26854612

  6. High-yield production of manganese peroxidase, lignin peroxidase, and versatile peroxidase in Phanerochaete chrysosporium.

    PubMed

    Coconi-Linares, Nancy; Magaña-Ortíz, Denis; Guzmán-Ortiz, Doralinda A; Fernández, Francisco; Loske, Achim M; Gómez-Lim, Miguel A

    2014-11-01

    The white-rot fungus Phanerochaete chrysosporium secretes extracellular oxidative enzymes during secondary metabolism, but lacks versatile peroxidase, an enzyme important in ligninolysis and diverse biotechnology processes. In this study, we report the genetic modification of a P. chrysosporium strain capable of co-expressing two endogenous genes constitutively, manganese peroxidase (mnp1) and lignin peroxidase (lipH8), and the codon-optimized vpl2 gene from Pleurotus eryngii. For this purpose, we employed a highly efficient transformation method based on the use of shock waves developed by our group. The expression of recombinant genes was verified by PCR, Southern blot, quantitative real-time PCR (qRT-PCR), and assays of enzymatic activity. The production yield of ligninolytic enzymes was up to four times higher in comparison to previously published reports. These results may represent significant progress toward the stable production of ligninolytic enzymes and the development of an effective fungal strain with promising biotechnological applications. PMID:25269601

  7. Enhanced mercury tolerance in Mytilus edulis: influence of Cu, Zn, and Cd pre-exposure and relationship to metal-binding proteins

    SciTech Connect

    Roesijadi, G.

    1983-06-01

    Experiments were conducted to determine whether exposure to Cu, Cd or Zn would induce enhanced mercury tolerance in mussels. The results indicated that enhanced tolerance can be elicited if exposure to Cu, Cd or Zn is sufficiently high that bioaccumulation of the metal and induction of metal-binding proteins will occur, and if the concentrations are below levels in which the exposure itself becomes toxic. 7 references. (ACR)

  8. Potassium contributes to zinc stress tolerance in peach (Prunus persica) seedlings by enhancing photosynthesis and the antioxidant defense system.

    PubMed

    Song, Z Z; Duan, C L; Guo, S L; Yang, Y; Feng, Y F; Ma, R J; Yu, M L

    2015-01-01

    Zinc (Zn) is considered to be a major industrial pollutant because excessive amounts can impair plant growth. In this paper, we found that peach 'Yoshihime' seedlings are promising Zn tolerant plants. However, heavy Zn toxicity (2 mM) damaged plant performance by disrupting biochemical processes, including photosynthesis, proline production, and K(+) nutrition. Notably, elevated external K(+) supply (10 mM) alleviated peach seedlings from Zn toxicity, evidenced by enhanced photosynthesis, antioxidant defense systems, and plant K(+) nutritional status. Moreover, the transcript levels of KUP (K(+) uptake) genes involved in K(+) acquisition, transport, and homeostasis were significantly upregulated following supply of sufficient K(+) upon Zn toxicity. In general, K(+) favorably contributes to improvements in internal K(+) homeostasis, via the help of K(+) transporters, further protecting plant photosynthesis and the antioxidative defense system. Our findings further benefit the study of the mechanisms underpinning heavy metal tolerance in woody plants. PMID:26345760

  9. Enhanced cadmium accumulation and tolerance in transgenic tobacco overexpressing rice metal tolerance protein gene OsMTP1 is promising for phytoremediation.

    PubMed

    Das, Natasha; Bhattacharya, Surajit; Maiti, Mrinal K

    2016-08-01

    One of the most grievous heavy metal pollutants in the environment is cadmium (Cd), which is not only responsible for the crop yield loss owing to its phytotoxicity, but also for the human health hazards as the toxic elements usually accumulate in the consumable parts of crop plants. In the present study, we aimed to isolate and functionally characterize the OsMTP1 gene from indica rice (Oryza sativa L. cv. IR64) to study its potential application for efficient phytoremediation of Cd. The 1257 bp coding DNA sequence (CDS) of OsMTP1 encodes a ∼46 kDa protein belonging to the cation diffusion facilitator (CDF) or metal tolerance/transport protein (MTP) family. The OsMTP1 transcript in rice plant was found to respond during external Cd stress. Heterologous expression of OsMTP1 in tobacco resulted in the reduction of Cd stress-induced phytotoxic effects, including growth inhibition, lipid peroxidation, and cell death. Compared to untransformed control, the transgenic tobacco plants showed enhanced vacuolar thiol content, indicating vacuolar localization of the sequestered Cd. The transgenic tobacco plants exhibited significantly higher biomass growth (2.2-2.8-folds) and hyperaccumulation of Cd (1.96-2.22-folds) compared to untransformed control under Cd exposure. The transgenic plants also showed moderate tolerance and accumulation of arsenic (As) upon exogenous As stress, signifying broad substrate specificity of OsMTP1. Together, findings of our research suggest that the transgenic tobacco plants overexpressing OsMTP1 with its hyperaccumulating activity and increased growth rate could be useful for future phytoremediation applications to clean up the Cd-contaminated soil. PMID:27214086

  10. Phenol-Oxidizing Peroxidases Contribute to the Protection of Plants from Ultraviolet Radiation Stress1

    PubMed Central

    Jansen, Marcel A.K.; van den Noort, Ria E.; Tan, M.Y. Adillah; Prinsen, Els; Lagrimini, L. Mark; Thorneley, Roger N.F.

    2001-01-01

    We have studied the mechanism of UV protection in two duckweed species (Lemnaceae) by exploiting the UV sensitivity of photosystem II as an in situ sensor for radiation stress. A UV-tolerant Spirodela punctata G.F.W. Meyer ecotype had significantly higher indole-3-acetic acid (IAA) levels than a UV-sensitive ecotype. Parallel work on Lemna gibba mutants suggested that UV tolerance is linked to IAA degradation rather than to levels of free or conjugated IAA. This linkage is consistent with a role for class III phenolic peroxidases, which have been implicated both in the degradation of IAA and the cross-linking of various UV-absorbing phenolics. Biochemical analysis revealed increased activity of a specific peroxidase isozyme in both UV-tolerant duckweed lines. The hypothesis that peroxidases play a role in UV protection was tested in a direct manner using genetically modified tobacco (Nicotiana sylvestris). It was found that increased activity of the anionic peroxidase correlated with increased tolerance to UV radiation as well as decreased levels of free auxin. We conclude that phenol-oxidizing peroxidases concurrently contribute to UV protection as well as the control of leaf and plant architecture. PMID:11457952

  11. Sulfur decreases cadmium translocation and enhances cadmium tolerance by promoting sulfur assimilation and glutathione metabolism in Brassica chinensis L.

    PubMed

    Liang, Taishuai; Ding, Han; Wang, Guodong; Kang, Jingquan; Pang, Hongxi; Lv, Jinyin

    2016-02-01

    We investigated the ameliorative role of sulfur (S) in protecting plants against cadmium (Cd) toxicity by using two pakchoi (Brassica chinensis L.) cultivars with different Cd tolerance levels. The exposure of pakchoi seedlings to 100μM Cd inhibited plant growth, increased superoxide content, enhanced membrane lipid peroxidation, and induced Cd accumulation in the roots and shoots. Application of S to Cd-stressed plants alleviated Cd-induced oxidative stress by promoting the capacity of the ascorbate (AsA)-glutathione (GSH) cycle, enhanced S assimilation by increasing the activity of ATP sulfurylase (ATPS) and o-acetylserine(thiol)lyase (OASTL), and decreased Cd translocation from the roots to the shoots by enhancing phytochelatins (PCs) biosynthesis. Results suggested that S reversed Cd-induced growth inhibition and oxidative stress by restraining Cd translocation from the roots to the shoots and upregulating S assimilation and GSH metabolism, including the AsA-GSH cycle and PCs synthesis. PMID:26513528

  12. Breaking Tolerance to Thyroid Antigens: Changing Concepts in Thyroid Autoimmunity

    PubMed Central

    Rapoport, Basil

    2014-01-01

    Thyroid autoimmunity involves loss of tolerance to thyroid proteins in genetically susceptible individuals in association with environmental factors. In central tolerance, intrathymic autoantigen presentation deletes immature T cells with high affinity for autoantigen-derived peptides. Regulatory T cells provide an alternative mechanism to silence autoimmune T cells in the periphery. The TSH receptor (TSHR), thyroid peroxidase (TPO), and thyroglobulin (Tg) have unusual properties (“immunogenicity”) that contribute to breaking tolerance, including size, abundance, membrane association, glycosylation, and polymorphisms. Insight into loss of tolerance to thyroid proteins comes from spontaneous and induced animal models: 1) intrathymic expression controls self-tolerance to the TSHR, not TPO or Tg; 2) regulatory T cells are not involved in TSHR self-tolerance and instead control the balance between Graves' disease and thyroiditis; 3) breaking TSHR tolerance involves contributions from major histocompatibility complex molecules (humans and induced mouse models), TSHR polymorphism(s) (humans), and alternative splicing (mice); 4) loss of tolerance to Tg before TPO indicates that greater Tg immunogenicity vs TPO dominates central tolerance expectations; 5) tolerance is induced by thyroid autoantigen administration before autoimmunity is established; 6) interferon-α therapy for hepatitis C infection enhances thyroid autoimmunity in patients with intact immunity; Graves' disease developing after T-cell depletion reflects reconstitution autoimmunity; and 7) most environmental factors (including excess iodine) “reveal,” but do not induce, thyroid autoimmunity. Micro-organisms likely exert their effects via bystander stimulation. Finally, no single mechanism explains the loss of tolerance to thyroid proteins. The goal of inducing self-tolerance to prevent autoimmune thyroid disease will require accurate prediction of at-risk individuals together with an antigen

  13. Overexpression of a blueberry-derived CBF enhances cold tolerance in a southern highbush blueberry cultivar

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Blueberry cultivars are subject to freezing damage in the winter and early spring. C-repeat binding factor (CBF) genes are transcription factors known to induce the expression of genes associated with cold acclimation and freezing tolerance. A CBF-encoding gene (BB-CBF) was isolated from the northe...

  14. Down-regulating alpha-galactosidase enhances freezing tolerance in transgenic petunia.

    PubMed

    Pennycooke, Joyce C; Jones, Michelle L; Stushnoff, Cecil

    2003-10-01

    Alpha-galactosidase (alpha-Gal; EC 3.2.1.22) is involved in many aspects of plant metabolism, including hydrolysis of the alpha-1,6 linkage of raffinose oligosaccharides during deacclimation. To examine the relationship between endogenous sugars and freezing stress, the expression of alpha-Gal was modified in transgenic petunia (Petunia x hybrida cv Mitchell). The tomato (Lycopersicon esculentum) Lea-Gal gene under the control of the Figwort Mosaic Virus promoter was introduced into petunia in the sense and antisense orientations using Agrobacterium tumefaciens-mediated transformation. RNA gel blots confirmed that alpha-Gal transcripts were reduced in antisense lines compared with wild type, whereas sense plants had increased accumulation of alpha-Gal mRNAs. alpha-Gal activity followed a similar trend, with reduced activity in antisense lines and increased activity in all sense lines evaluated. Raffinose content of nonacclimated antisense plants increased 12- to 22-fold compared with wild type, and 22- to 53-fold after cold acclimation. Based upon electrolyte leakage tests, freezing tolerance of the antisense lines increased from -4 degrees C for cold-acclimated wild-type plants to -8 degrees C for the most tolerant antisense line. Down-regulating alpha-Gal in petunia results in an increase in freezing tolerance at the whole-plant level in nonacclimated and cold-acclimated plants, whereas overexpression of the alpha-Gal gene caused a decrease in endogenous raffinose and impaired freezing tolerance. These results suggest that engineering raffinose metabolism by transformation with alpha-Gal provides an additional method for improving the freezing tolerance of plants. PMID:14500789

  15. Down-Regulating α-Galactosidase Enhances Freezing Tolerance in Transgenic Petunia1

    PubMed Central

    Pennycooke, Joyce C.; Jones, Michelle L.; Stushnoff, Cecil

    2003-01-01

    α-Galactosidase (α-Gal; EC 3.2.1.22) is involved in many aspects of plant metabolism, including hydrolysis of the α-1,6 linkage of raffinose oligosaccharides during deacclimation. To examine the relationship between endogenous sugars and freezing stress, the expression of α-Gal was modified in transgenic petunia (Petunia × hybrida cv Mitchell). The tomato (Lycopersicon esculentum) Lea-Gal gene under the control of the Figwort Mosaic Virus promoter was introduced into petunia in the sense and antisense orientations using Agrobacterium tumefaciens-mediated transformation. RNA gel blots confirmed that α-Gal transcripts were reduced in antisense lines compared with wild type, whereas sense plants had increased accumulation of α-Gal mRNAs. α-Gal activity followed a similar trend, with reduced activity in antisense lines and increased activity in all sense lines evaluated. Raffinose content of nonacclimated antisense plants increased 12- to 22-fold compared with wild type, and 22- to 53-fold after cold acclimation. Based upon electrolyte leakage tests, freezing tolerance of the antisense lines increased from –4°C for cold-acclimated wild-type plants to –8°C for the most tolerant antisense line. Down-regulating α-Gal in petunia results in an increase in freezing tolerance at the whole-plant level in nonacclimated and cold-acclimated plants, whereas overexpression of the α-Gal gene caused a decrease in endogenous raffinose and impaired freezing tolerance. These results suggest that engineering raffinose metabolism by transformation with α-Gal provides an additional method for improving the freezing tolerance of plants. PMID:14500789

  16. Cage-bell Pt-Pd nanostructures with enhanced catalytic properties and superior methanol tolerance for oxygen reduction reaction

    NASA Astrophysics Data System (ADS)

    Chen, Dong; Ye, Feng; Liu, Hui; Yang, Jun

    2016-04-01

    Precisely tailoring the structure and fully making use of the components of nanoparticles are effective to enhance their catalytic performance for a given reaction. We herein demonstrate the design of cage-bell structured Pt-Pd nanoparticles, where a Pd shell is deliberately selected to enhance the catalytic property and methanol tolerance of Pt for oxygen reduction reaction. This strategy starts with the synthesis of core-shell Pt@Ag nanoparticles, followed by galvanic replacement reaction between the Ag shell and Pd2+ ions to form core-shell-shell Pt@Ag@Ag-Pd nanoparticles with a Pt core and double shells composed of Ag at inner and alloy Ag-Pd at outer, respectively. Then, the core-shell-shell templates are agitated with saturated NaCl solution to eliminate the Ag component from the double shells, leading to the formation of bimetallic Pt-Pd nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a porous Pd shell, which show enhanced catalytic activity for oxygen reduction compared with that of the Pt seeds due to the additional catalysis from Pd shell. In addition, owing to the different diffusion behavior of methanol and oxygen molecules in the porous Pd shell, the Pt-Pd cage-bell nanostructures also exhibit superior methanol tolerant property in catalyzing the oxygen reduction.

  17. Cage-bell Pt-Pd nanostructures with enhanced catalytic properties and superior methanol tolerance for oxygen reduction reaction

    PubMed Central

    Chen, Dong; Ye, Feng; Liu, Hui; Yang, Jun

    2016-01-01

    Precisely tailoring the structure and fully making use of the components of nanoparticles are effective to enhance their catalytic performance for a given reaction. We herein demonstrate the design of cage-bell structured Pt-Pd nanoparticles, where a Pd shell is deliberately selected to enhance the catalytic property and methanol tolerance of Pt for oxygen reduction reaction. This strategy starts with the synthesis of core-shell Pt@Ag nanoparticles, followed by galvanic replacement reaction between the Ag shell and Pd2+ ions to form core-shell-shell Pt@Ag@Ag-Pd nanoparticles with a Pt core and double shells composed of Ag at inner and alloy Ag-Pd at outer, respectively. Then, the core-shell-shell templates are agitated with saturated NaCl solution to eliminate the Ag component from the double shells, leading to the formation of bimetallic Pt-Pd nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a porous Pd shell, which show enhanced catalytic activity for oxygen reduction compared with that of the Pt seeds due to the additional catalysis from Pd shell. In addition, owing to the different diffusion behavior of methanol and oxygen molecules in the porous Pd shell, the Pt-Pd cage-bell nanostructures also exhibit superior methanol tolerant property in catalyzing the oxygen reduction. PMID:27079897

  18. Cage-bell Pt-Pd nanostructures with enhanced catalytic properties and superior methanol tolerance for oxygen reduction reaction.

    PubMed

    Chen, Dong; Ye, Feng; Liu, Hui; Yang, Jun

    2016-01-01

    Precisely tailoring the structure and fully making use of the components of nanoparticles are effective to enhance their catalytic performance for a given reaction. We herein demonstrate the design of cage-bell structured Pt-Pd nanoparticles, where a Pd shell is deliberately selected to enhance the catalytic property and methanol tolerance of Pt for oxygen reduction reaction. This strategy starts with the synthesis of core-shell Pt@Ag nanoparticles, followed by galvanic replacement reaction between the Ag shell and Pd(2+) ions to form core-shell-shell Pt@Ag@Ag-Pd nanoparticles with a Pt core and double shells composed of Ag at inner and alloy Ag-Pd at outer, respectively. Then, the core-shell-shell templates are agitated with saturated NaCl solution to eliminate the Ag component from the double shells, leading to the formation of bimetallic Pt-Pd nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a porous Pd shell, which show enhanced catalytic activity for oxygen reduction compared with that of the Pt seeds due to the additional catalysis from Pd shell. In addition, owing to the different diffusion behavior of methanol and oxygen molecules in the porous Pd shell, the Pt-Pd cage-bell nanostructures also exhibit superior methanol tolerant property in catalyzing the oxygen reduction. PMID:27079897

  19. Accelerating peroxidase mimicking nanozymes using DNA

    NASA Astrophysics Data System (ADS)

    Liu, Biwu; Liu, Juewen

    2015-08-01

    DNA-capped iron oxide nanoparticles are nearly 10-fold more active as a peroxidase mimic for TMB oxidation than naked nanoparticles. To understand the mechanism, the effect of DNA length and sequence is systematically studied, and other types of polymers are also compared. This rate enhancement is more obvious with longer DNA and, in particular, poly-cytosine. Among the various polymer coatings tested, DNA offers the highest rate enhancement. A similar acceleration is also observed for nanoceria. On the other hand, when the positively charged TMB substrate is replaced by the negatively charged ABTS, DNA inhibits oxidation. Therefore, the negatively charged phosphate backbone and bases of DNA can increase TMB binding by the iron oxide nanoparticles, thus facilitating the oxidation reaction in the presence of hydrogen peroxide.DNA-capped iron oxide nanoparticles are nearly 10-fold more active as a peroxidase mimic for TMB oxidation than naked nanoparticles. To understand the mechanism, the effect of DNA length and sequence is systematically studied, and other types of polymers are also compared. This rate enhancement is more obvious with longer DNA and, in particular, poly-cytosine. Among the various polymer coatings tested, DNA offers the highest rate enhancement. A similar acceleration is also observed for nanoceria. On the other hand, when the positively charged TMB substrate is replaced by the negatively charged ABTS, DNA inhibits oxidation. Therefore, the negatively charged phosphate backbone and bases of DNA can increase TMB binding by the iron oxide nanoparticles, thus facilitating the oxidation reaction in the presence of hydrogen peroxide. Electronic supplementary information (ESI) available: Methods, TEM, UV-vis and DLS data. See DOI: 10.1039/c5nr04176g

  20. Peroxidase extraction from jicama skin peels for phenol removal

    NASA Astrophysics Data System (ADS)

    Chiong, T.; Lau, S. Y.; Khor, E. H.; Danquah, M. K.

    2016-06-01

    Phenol and its derivatives exist in various types of industrial effluents, and are known to be harmful to aquatic lives even at low concentrations. Conventional treatment technologies for phenol removal are challenged with long retention time, high energy consumption and process cost. Enzymatic treatment has emerged as an alternative technology for phenol removal from wastewater. These enzymes interact with aromatic compounds including phenols in the presence of hydrogen peroxide, forming free radicals which polymerize spontaneously to produce insoluble phenolic polymers. This work aims to extract peroxidase from agricultural wastes materials and establish its application for phenol removal. Peroxidase was extracted from jicama skin peels under varying extraction conditions of pH, sample-to-buffer ratio (w/v %) and temperature. Experimental results showed that extraction process conducted at pH 10, 40% w/v and 25oC demonstrated a peroxidase activity of 0.79 U/mL. Elevated temperatures slightly enhanced the peroxidase activities. Jicama peroxidase extracted at optimum extraction conditions demonstrated a phenol removal efficiency of 87.5% at pH 7. Phenol removal efficiency was ∼ 97% in the range of 30 - 40oC, and H2O2 dosage has to be kept below 100 mM for maximum removal under phenol concentration tested.

  1. Overexpression of a wheat phospholipase D gene, TaPLDα, enhances tolerance to drought and osmotic stress in Arabidopsis thaliana.

    PubMed

    Wang, Junbin; Ding, Bo; Guo, Yaolin; Li, Ming; Chen, Shuaijun; Huang, Guozhong; Xie, Xiaodong

    2014-07-01

    Phospholipase D (PLD) is crucial for plant responses to stress and signal transduction, however, the regulatory mechanism of PLD in abiotic stress is not completely understood; especially, in crops. In this study, we isolated a gene, TaPLDα, from common wheat (Triticum aestivum L.). Analysis of the amino acid sequence of TaPLDα revealed a highly conserved C2 domain and two characteristic HKD motifs, which is similar to other known PLD family genes. Further characterization revealed that TaPLDα expressed differentially in various organs, such as roots, stems, leaves and spikelets of wheat. After treatment with abscisic acid (ABA), methyl jasmonate, dehydration, polyethylene glycol and NaCl, the expression of TaPLDα was up-regulated in shoots. Subsequently, we generated TaPLDα-overexpressing transgenic Arabidopsis lines under the control of the dexamethasone-inducible 35S promoter. The overexpression of TaPLDα in Arabidopsis resulted in significantly enhanced tolerance to drought, as shown by reduced chlorosis and leaf water loss, higher relative water content and lower relative electrolyte leakage than the wild type. Moreover, the TaPLDα-overexpressing plants exhibited longer roots in response to mannitol treatment. In addition, the seeds of TaPLDα-overexpressing plants showed hypersensitivity to ABA and osmotic stress. Under dehydration, the expression of several stress-related genes, RD29A, RD29B, KIN1 and RAB18, was up-regulated to a higher level in TaPLDα-overexpressing plants than in wild type. Taken together, our results indicated that TaPLDα can enhance tolerance to drought and osmotic stress in Arabidopsis and represents a potential candidate gene to enhance stress tolerance in crops. PMID:24705986

  2. Peroxidase and peroxidase-oxidase activities of isolated human myeloperoxidases.

    PubMed Central

    Svensson, B E; Domeij, K; Lindvall, S; Rydell, G

    1987-01-01

    Isolated neutrophils from healthy donors were used for the isolation of four highly purified forms of myeloperoxidase as determined by spectral (A430/A280 ratio 0.80-0.87) and enzyme-activity measurements. Although the myeloperoxidases exhibited different elution profiles on cation-exchange chromatography, gel filtration indicated similar relative molecular masses. When these forms were assayed for peroxidase and peroxidase-oxidase activities with several substrates, they all exhibited virtually the same specific activities. These results suggest that possible functional differences between the enzymes may be related to differences in their sites of action rather than to differences in enzyme activity. Myeloperoxidase from a patient with chronic myeloid leukaemia also revealed a similar heterogeneity on cation-exchange chromatography. However, this myeloperoxidase contained in addition one form with a lower and one form with a higher relative molecular mass, as indicated by gel-filtration chromatography. PMID:3036098

  3. A rice stress-responsive NAC gene enhances tolerance of transgenic wheat to drought and salt stresses.

    PubMed

    Saad, Abu Sefyan I; Li, Xu; Li, He-Ping; Huang, Tao; Gao, Chun-Sheng; Guo, Mao-Wei; Cheng, Wei; Zhao, Guang-Yao; Liao, Yu-Cai

    2013-04-01

    Drought and salinity are the primary factors limiting wheat production worldwide. It has been shown that a rice stress-responsive transcription factor encoded by the rice NAC1 gene (SNAC1) plays an important role in drought stress tolerance. Therefore, we introduced the SNAC1 gene under the control of a maize ubiquitin promoter into an elite Chinese wheat variety Yangmai12. Plants expressing SNAC1 displayed significantly enhanced tolerance to drought and salinity in multiple generations, and contained higher levels of water and chlorophyll in their leaves, as compared to wild type. In addition, the fresh and dry weights of the roots of these plants were also increased, and the plants had increased sensitivities to abscisic acid (ABA), which inhibited root and shoot growth. Furthermore, quantitative real-time polymerase chain reactions revealed that the expressions of genes involved in abiotic stress/ABA signaling, such as wheat 1-phosphatidylinositol-3-phosphate-5-kinase, sucrose phosphate synthase, type 2C protein phosphatases and regulatory components of ABA receptor, were effectively regulated by the alien SNAC1 gene. These results indicated high and functional expression of the rice SNAC1 gene in wheat. And our study provided a promising approach to improve the tolerances of wheat cultivars to drought and salinity through genetic engineering. PMID:23415326

  4. Disruption of the Arabidopsis Defense Regulator Genes SAG101, EDS1, and PAD4 Confers Enhanced Freezing Tolerance.

    PubMed

    Chen, Qin-Fang; Xu, Le; Tan, Wei-Juan; Chen, Liang; Qi, Hua; Xie, Li-Juan; Chen, Mo-Xian; Liu, Bin-Yi; Yu, Lu-Jun; Yao, Nan; Zhang, Jian-Hua; Shu, Wensheng; Xiao, Shi

    2015-10-01

    In Arabidopsis, three lipase-like regulators, SAG101, EDS1, and PAD4, act downstream of resistance protein-associated defense signaling. Although the roles of SAG101, EDS1, and PAD4 in biotic stress have been extensively studied, little is known about their functions in plant responses to abiotic stresses. Here, we show that SAG101, EDS1, and PAD4 are involved in the regulation of freezing tolerance in Arabidopsis. With or without cold acclimation, the sag101, eds1, and pad4 single mutants, as well as their double mutants, exhibited similarly enhanced tolerance to freezing temperatures. Upon cold exposure, the sag101, eds1, and pad4 mutants showed increased transcript levels of C-REPEAT/DRE BINDING FACTORs and their regulons compared with the wild type. Moreover, freezing-induced cell death and accumulation of hydrogen peroxide were ameliorated in sag101, eds1, and pad4 mutants. The sag101, eds1, and pad4 mutants had much lower salicylic acid (SA) and diacylglycerol (DAG) contents than the wild type, and exogenous application of SA and DAG compromised the freezing tolerance of the mutants. Furthermore, SA suppressed the cold-induced expression of DGATs and DGKs in the wild-type leaves. These findings indicate that SAG101, EDS1, and PAD4 are involved in the freezing response in Arabidopsis, at least in part, by modulating the homeostasis of SA and DAG. PMID:26149542

  5. Naturally evolved enhanced Cd tolerance of Dianthus carthusianorum L. is not related to accumulation of thiol peptides and organic acids.

    PubMed

    Wójcik, Małgorzata; Dresler, Sławomir; Plak, Andrzej; Tukiendorf, Anna

    2015-05-01

    Two contrasting ecotypes of Dianthus carthusianorum L., metallicolous (M) and nonmetallicolous (NM), were cultivated in hydroponics at 0-50 μM Cd for 14 days to compare their Cd accumulation, sensitivity and tolerance mechanisms. While both ecotypes contained similar concentrations of Cd in the shoots and roots, the M ecotype was more Cd-tolerant (as measured by fresh weight production and root and leaf viability). Both ecotypes accumulated phytochelatins (PCs) in response to Cd with a higher amount thereof found in the NM ecotype. Concentrations of PCs remained unchanged with increasing Cd concentrations in the root tissues, but their content in the shoots increased. The addition of L-buthionine-sulfoximine (BSO) diminished glutathione (GSH) accumulation and arrested PC production, which increased the sensitivity to Cd of the NM, but not M ecotype. Organic acids (malate and citrate) as well as proline accumulation did not change significantly after Cd exposition and was at the same level in both ecotypes. The enhanced Cd tolerance of the M ecotype of D. carthusianorum cannot be explained in terms of restricted Cd uptake and differential production of PCs, organic acids or proline; some other mechanisms must be involved in its adaptation to the high Cd content in the environment. PMID:25510617

  6. Physiological and molecular characterization of the enhanced salt tolerance induced by low-dose gamma irradiation in Arabidopsis seedlings

    SciTech Connect

    Qi, Wencai; Zhang, Liang; Xu, Hangbo; Wang, Lin; Jiao, Zhen

    2014-07-25

    Highlights: • 50-Gy gamma irradiation markedly promotes the seedling growth under salt stress in Arabidopsis. • The contents of H{sub 2}O{sub 2} and MDA are obviously reduced by low-dose gamma irradiation under salt stress. • Low-dose gamma irradiation stimulates the activities of antioxidant enzymes under salt stress. • Proline accumulation is required for the low-gamma-ray-induced salt tolerance. • Low gamma rays differentially regulate the expression of genes related to salt stress. - Abstract: It has been established that gamma rays at low doses stimulate the tolerance to salt stress in plants. However, our knowledge regarding the molecular mechanism underlying the enhanced salt tolerance remains limited. In this study, we found that 50-Gy gamma irradiation presented maximal beneficial effects on germination index and root length in response to salt stress in Arabidopsis seedlings. The contents of H{sub 2}O{sub 2} and MDA in irradiated seedlings under salt stress were significantly lower than those of controls. The activities of antioxidant enzymes and proline levels in the irradiated seedlings were markedly increased compared with the controls. Furthermore, transcriptional expression analysis of selected genes revealed that some components of salt stress signaling pathways were stimulated by low-dose gamma irradiation under salt stress. Our results suggest that gamma irradiation at low doses alleviates the salt stress probably by modulating the physiological responses as well as stimulating the stress signal transduction in Arabidopsis seedlings.

  7. Transgenic Brassica chinensis plants expressing a bacterial codA gene exhibit enhanced tolerance to extreme temperature and high salinity*

    PubMed Central

    Wang, Qing-bin; Xu, Wen; Xue, Qing-zhong; Su, Wei-ai

    2010-01-01

    Transgenic Brassica compestris L. spp. chinensis plants expressing a choline oxidase (codA) gene from Arthrobacter globiformis were obtained through Agrobacterium tumefaciens-mediated transformation. In the transgenic plants, codA gene expression and its product transportation to chloroplasts were detected by the enzyme-linked immunosorbent assay (ELISA) examination, immunogold localization, and 1H-nuclear magnetic resonance (1H-NMR). Stress tolerance was evaluated in the T3 plants under extreme temperature and salinity conditions. The plants of transgenic line 1 (L1) showed significantly higher net photosynthetic rate (P n) and P n recovery rate under high (45 °C, 4 h) and low temperature (1 °C, 48 h) treatments, and higher photosynthetic rate under high salinity conditions (100, 200, and 300 mmol/L NaCl, respectively) than the wild-type plants. The enhanced tolerance to high temperature and high salinity stresses in transgenic plants is associated with the accumulation of betaine, which is not found in the wild-type plants. Our results indicate that the introduction of codA gene from Arthrobacter globiformis into Brassica compestris L. spp. chinensis could be a potential strategy for improving the plant tolerance to multiple stresses. PMID:21043054

  8. Transgenic Brassica chinensis plants expressing a bacterial codA gene exhibit enhanced tolerance to extreme temperature and high salinity.

    PubMed

    Wang, Qing-bin; Xu, Wen; Xue, Qing-zhong; Su, Wei-ai

    2010-11-01

    Transgenic Brassica compestris L. spp. chinensis plants expressing a choline oxidase (codA) gene from Arthrobacter globiformis were obtained through Agrobacterium tumefaciens-mediated transformation. In the transgenic plants, codA gene expression and its product transportation to chloroplasts were detected by the enzyme-linked immunosorbent assay (ELISA) examination, immunogold localization, and (1)H-nuclear magnetic resonance ((1)H-NMR). Stress tolerance was evaluated in the T(3) plants under extreme temperature and salinity conditions. The plants of transgenic line 1 (L1) showed significantly higher net photosynthetic rate (P(n)) and P(n) recovery rate under high (45 °C, 4 h) and low temperature (1 °C, 48 h) treatments, and higher photosynthetic rate under high salinity conditions (100, 200, and 300 mmol/L NaCl, respectively) than the wild-type plants. The enhanced tolerance to high temperature and high salinity stresses in transgenic plants is associated with the accumulation of betaine, which is not found in the wild-type plants. Our results indicate that the introduction of codA gene from Arthrobacter globiformis into Brassica compestris L. spp. chinensis could be a potential strategy for improving the plant tolerance to multiple stresses. PMID:21043054

  9. Enhancement of tolerance of Ganoderma lucidum to cadmium by nitric oxide.

    PubMed

    Guo, Shanshan; Yao, Yuan; Zuo, Lei; Shi, Wenjin; Gao, Ni; Xu, Heng

    2016-01-01

    Nitric oxide (NO) is considered as a signaling molecule involved in regulation of diverse physiological processes and stress responses in animals and plants. However, whether NO regulates fungal, particularly edible fungi, response to heavy metal stresses, is unknown. This study investigated the effect of nitric oxide on biological responses of mycelia of Ganoderma lucidum to cadmium (Cd) toxicity. Exposure of Ganoderma lucidum to Cd (400 µM) triggered production of H2O2 and O2(-) in the mycelia and further induced lipid peroxidation as well as sharply decrease of fresh biomass. However, such an effect can be reversed by exogenous supply of NO. Mycelia treated with 100 µM SNP accumulated less H2O2, O2(-), thiobarbituric acid reactive substances (TBARS), and fresh biomass of this treatment was improved. Treatment with SNP significantly increased activities of antioxidant enzyme (peroxidase and catalase) to resist Cd stress. Meanwhile, NO-mediated alleviation of Cd toxicity was closely related to the accumulated proline as well as reduced Cd accumulation. These results suggested that NO plays a crucial role in preventing the mycelia of Ganoderma lucidum from Cd toxicity. PMID:26411634

  10. Transgenic tobacco plants overexpressing a grass PpEXP1 gene exhibit enhanced tolerance to heat stress.

    PubMed

    Xu, Qian; Xu, Xiao; Shi, Yang; Xu, Jichen; Huang, Bingru

    2014-01-01

    Heat stress is a detrimental abiotic stress limiting the growth of many plant species and is associated with various cellular and physiological damages. Expansins are a family of proteins which are known to play roles in regulating cell wall elongation and expansion, as well as other growth and developmental processes. The in vitro roles of expansins regulating plant heat tolerance are not well understood. The objectives of this study were to isolate and clone an expansin gene in a perennial grass species (Poa pratensis) and to determine whether over-expression of expansin may improve plant heat tolerance. Tobacco (Nicotiana tabacum) was used as the model plant for gene transformation and an expansin gene PpEXP1 from Poa pratensis was cloned. Sequence analysis showed PpEXP1 belonged to α-expansins and was closely related to two expansin genes in other perennial grass species (Festuca pratensis and Agrostis stolonifera) as well as Triticum aestivum, Oryza sativa, and Brachypodium distachyon. Transgenic tobacco plants over-expressing PpEXP1 were generated through Agrobacterium-mediated transformation. Under heat stress (42°C) in growth chambers, transgenic tobacco plants over-expressing the PpEXP1 gene exhibited a less structural damage to cells, lower electrolyte leakage, lower levels of membrane lipid peroxidation, and lower content of hydrogen peroxide, as well as higher chlorophyll content, net photosynthetic rate, relative water content, activity of antioxidant enzyme, and seed germination rates, compared to the wild-type plants. These results demonstrated the positive roles of PpEXP1 in enhancing plant tolerance to heat stress and the possibility of using expansins for genetic modification of cool-season perennial grasses in the development of heat-tolerant germplasm and cultivars. PMID:25003197

  11. Transgenic Tobacco Plants Overexpressing a Grass PpEXP1 Gene Exhibit Enhanced Tolerance to Heat Stress

    PubMed Central

    Xu, Qian; Xu, Xiao; Shi, Yang; Xu, Jichen; Huang, Bingru

    2014-01-01

    Heat stress is a detrimental abiotic stress limiting the growth of many plant species and is associated with various cellular and physiological damages. Expansins are a family of proteins which are known to play roles in regulating cell wall elongation and expansion, as well as other growth and developmental processes. The in vitro roles of expansins regulating plant heat tolerance are not well understood. The objectives of this study were to isolate and clone an expansin gene in a perennial grass species (Poa pratensis) and to determine whether over-expression of expansin may improve plant heat tolerance. Tobacco (Nicotiana tabacum) was used as the model plant for gene transformation and an expansin gene PpEXP1 from Poa pratensis was cloned. Sequence analysis showed PpEXP1 belonged to α-expansins and was closely related to two expansin genes in other perennial grass species (Festuca pratensis and Agrostis stolonifera) as well as Triticum aestivum, Oryza sativa, and Brachypodium distachyon. Transgenic tobacco plants over-expressing PpEXP1 were generated through Agrobacterium-mediated transformation. Under heat stress (42°C) in growth chambers, transgenic tobacco plants over-expressing the PpEXP1 gene exhibited a less structural damage to cells, lower electrolyte leakage, lower levels of membrane lipid peroxidation, and lower content of hydrogen peroxide, as well as higher chlorophyll content, net photosynthetic rate, relative water content, activity of antioxidant enzyme, and seed germination rates, compared to the wild-type plants. These results demonstrated the positive roles of PpEXP1 in enhancing plant tolerance to heat stress and the possibility of using expansins for genetic modification of cool-season perennial grasses in the development of heat-tolerant germplasm and cultivars. PMID:25003197

  12. Expression of plant ferredoxin-like protein (PFLP) enhances tolerance to heat stress in Arabidopsis thaliana.

    PubMed

    Lin, Yi-Hsien; Huang, Li-Fen; Hase, Tashiharu; Huang, Hsiang-En; Feng, Teng-Yung

    2015-03-25

    Under adverse environments, plants produce reactive oxygen species (ROS), which can trigger cell death when their accumulation surpasses the antioxidant capacity of ROS scavenging systems. These systems function in chloroplasts mainly through the ascorbate-mediated water-water cycle, in which ascorbate is photoreduced by ferredoxin in the photosynthetic system. Our previous study showed that the fraction of the reduced form of ascorbate was increased in ferredoxin-transgenic Arabidopsis (CPF) plants which overexpressed plant ferredoxin-like protein (PFLP) in their chloroplasts. Thus, we hypothesized that expression of PFLP could alter the tolerance of plants to abiotic stresses through increasing reduced form of ascorbate. In this study, we found that two CPF lines exhibited lower mortality rates at five days, following two days of heat treatment. Compared to non-transgenic wild type (Col-0) plants, CPF plants exhibited decreased H2O2 content, MDA accumulation, and ion leakage after heat treatment. To confirm the efficacy of ferredoxin against heat stress in chloroplasts, we evaluated two RNA interference (RNAi) lines on two endogenous ferredoxin isoforms, Atfd1 or Atfd2, of Arabidopsis plants. Both lines not only decreased their amounts of ascorbate, but also exhibited adverse reactions following heat treatment. Based on these results, we conclude that expression of PFLP in chloroplasts can confer tolerance to heat stress. This tolerance might be associated with the increasing of ascorbate in plants. PMID:25527360

  13. Engineering Clostridium beijerinckii with the Cbei_4693 gene knockout for enhanced ferulic acid tolerance.

    PubMed

    Liu, Jun; Guo, Ting; Shen, Xiaoning; Xu, Jiahui; Wang, Junzhi; Wang, Yanyan; Liu, Dong; Niu, Huanqing; Liang, Lei; Ying, Hanjie

    2016-07-10

    A mutant strain of Clostridium beijerinckii NCIMB 8052, C. beijerinckii M11, which exhibited ferulic acid tolerance up to 0.9g/L, was generated using atmospheric pressure glow discharge and high-throughput screening. Comparative genomic analysis revealed that this strain harbored a mutation of the Cbei_4693 gene, which encodes a hypothetical protein suspected to be an NADPH-dependent FMN reductase. After disrupting the Cbei_4693 gene in C. beijerinckii NCIMB 8052 using the ClosTron group II intron-based gene inactivation system, we obtained the Cbei_4693 gene inactivated mutant strain, C. beijerinckii 4693::int. Compared with C. beijerinckii NCIMB 8052, 6.23g/L of butanol was produced in P2 medium containing 0.5g/L of ferulic acid by 4693::int, and the ferulic acid tolerance was also significantly increased up to 0.8g/L. These data showed, for the first time, that the Cbei_4693 gene plays an important role in regulating ferulic acid tolerance in ABE fermentation by C. beijerinckii. PMID:27164255

  14. Mixed cropping has the potential to enhance flood tolerance of drought-adapted grain crops.

    PubMed

    Iijima, Morio; Awala, Simon K; Watanabe, Yoshinori; Kawato, Yoshimasa; Fujioka, Yuichiro; Yamane, Koji; Wada, Kaede C

    2016-03-15

    Recently, the occurrences of extreme flooding and drought, often in the same areas, have increased due to climate change. Wetland plant species are known to oxygenate their rhizospheres by releasing oxygen (O2) from their roots. We tested the hypothesis that wetland species could help upland species under flood conditions; that is, O2 released from the wetland crop roots would ameliorate rhizosphere O2-deficient stress and hence facilitate upland crop root function. Flooding tolerance of upland-adapted staple crops-pearl millet (Pennisetum glaucum) and sorghum (Sorghum bicolor) mix-cropped with rice (Oryza spp.) was investigated in glasshouse and laboratory. We found a phenomenon that strengthens the flood tolerance of upland crops when two species-one wetland and one drought tolerant-were grown using the mixed cropping technique that results in close tangling of their root systems. This technique improved the photosynthetic and transpiration rates of upland crops subjected to flood stress (O2-deficient nutrient culture). Shoot relative growth rates during the flooding period (24 days) tended to be higher under mixed cropping compared with single cropping. Radial oxygen loss from the wetland crop roots might be contributed to the phenomenon observed. Mixed cropping of wet and dryland crops is a new concept that has the potential to overcome flood stress under variable environmental conditions. PMID:26803216

  15. Lignin-degrading peroxidases of Phanerochaete chrysosporium.

    PubMed

    Cai, D; Tien, M

    1993-07-01

    Lignin and manganese peroxidases are secreted by the basidiomycete Phanerochaete chrysosporium during secondary metabolism. These enzymes play major roles in lignin degradation. The active site amino acid sequence of these lignin-degrading peroxidases is similar to that of horseradish peroxidase (HRP) and cytochrome c peroxidase (CcP). The mechanism by which they oxidize substrates also appears to be the similar. pH has a similar effect on lignin peroxidase compound I formation as on HRP or CcP; however, the pKa controlling compound I formation for lignin peroxidase appears to be much lower. Lignin-degrading peroxidases are able to catalyze the oxidation of substrates with high redox potential. This unique ability is consistent with a heme active site of low electron density, which is indicated by high redox potential. PMID:7763834

  16. Proteomic Analyses Reveal the Mechanism of Dunaliella salina Ds-26-16 Gene Enhancing Salt Tolerance in Escherichia coli

    PubMed Central

    Wang, Yanlong; Hu, Bin; Du, Shipeng; Gao, Shan; Chen, Xiwen; Chen, Defu

    2016-01-01

    We previously screened the novel gene Ds-26-16 from a 4 M salt-stressed Dunaliella salina cDNA library and discovered that this gene conferred salt tolerance to broad-spectrum organisms, including E. coli (Escherichia coli), Haematococcus pluvialis and tobacco. To determine the mechanism of this gene conferring salt tolerance, we studied the proteome of E. coli overexpressing the full-length cDNA of Ds-26-16 using the iTRAQ (isobaric tags for relative and absolute quantification) approach. A total of 1,610 proteins were identified, which comprised 39.4% of the whole proteome. Of the 559 differential proteins, 259 were up-regulated and 300 were down-regulated. GO (gene ontology) and KEGG (Kyoto encyclopedia of genes and genomes) enrichment analyses identified 202 major proteins, including those involved in amino acid and organic acid metabolism, energy metabolism, carbon metabolism, ROS (reactive oxygen species) scavenging, membrane proteins and ABC (ATP binding cassette) transporters, and peptidoglycan synthesis, as well as 5 up-regulated transcription factors. Our iTRAQ data suggest that Ds-26-16 up-regulates the transcription factors in E. coli to enhance salt resistance through osmotic balance, energy metabolism, and oxidative stress protection. Changes in the proteome were also observed in E. coli overexpressing the ORF (open reading frame) of Ds-26-16. Furthermore, pH, nitric oxide and glycerol content analyses indicated that Ds-26-16 overexpression increases nitric oxide content but has no effect on glycerol content, thus confirming that enhanced nitric oxide synthesis via lower intercellular pH was one of the mechanisms by which Ds-26-16 confers salt tolerance to E. coli. PMID:27135411

  17. Proteomic Analyses Reveal the Mechanism of Dunaliella salina Ds-26-16 Gene Enhancing Salt Tolerance in Escherichia coli.

    PubMed

    Wang, Yanlong; Hu, Bin; Du, Shipeng; Gao, Shan; Chen, Xiwen; Chen, Defu

    2016-01-01

    We previously screened the novel gene Ds-26-16 from a 4 M salt-stressed Dunaliella salina cDNA library and discovered that this gene conferred salt tolerance to broad-spectrum organisms, including E. coli (Escherichia coli), Haematococcus pluvialis and tobacco. To determine the mechanism of this gene conferring salt tolerance, we studied the proteome of E. coli overexpressing the full-length cDNA of Ds-26-16 using the iTRAQ (isobaric tags for relative and absolute quantification) approach. A total of 1,610 proteins were identified, which comprised 39.4% of the whole proteome. Of the 559 differential proteins, 259 were up-regulated and 300 were down-regulated. GO (gene ontology) and KEGG (Kyoto encyclopedia of genes and genomes) enrichment analyses identified 202 major proteins, including those involved in amino acid and organic acid metabolism, energy metabolism, carbon metabolism, ROS (reactive oxygen species) scavenging, membrane proteins and ABC (ATP binding cassette) transporters, and peptidoglycan synthesis, as well as 5 up-regulated transcription factors. Our iTRAQ data suggest that Ds-26-16 up-regulates the transcription factors in E. coli to enhance salt resistance through osmotic balance, energy metabolism, and oxidative stress protection. Changes in the proteome were also observed in E. coli overexpressing the ORF (open reading frame) of Ds-26-16. Furthermore, pH, nitric oxide and glycerol content analyses indicated that Ds-26-16 overexpression increases nitric oxide content but has no effect on glycerol content, thus confirming that enhanced nitric oxide synthesis via lower intercellular pH was one of the mechanisms by which Ds-26-16 confers salt tolerance to E. coli. PMID:27135411

  18. Enhancing the methanol tolerance of platinum nanoparticles for the cathode reaction of direct methanol fuel cells through a geometric design

    PubMed Central

    Feng, Yan; Ye, Feng; Liu, Hui; Yang, Jun

    2015-01-01

    Mastery over the structure of nanoparticles might be an effective way to enhance their performance for a given application. Herein we demonstrate the design of cage-bell nanostructures to enhance the methanol tolerance of platinum (Pt) nanoparticles while remaining their catalytic activity for oxygen reduction reaction. This strategy starts with the synthesis of core-shell-shell nanoparticles with Pt and silver (Ag) residing respectively in the core and inner shell regions, which are then agitated with saturated sodium chloride (NaCl) solution to eliminate the Ag component from the inner shell region, leading to the formation of bimetallic nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a metal shell with nano-channels, which exhibit superior methanol-tolerant property in catalyzing oxygen reduction reaction due to the different diffusion behaviour of methanol and oxygen in the porous metal shell of cage-bell structured nanoparticles. In particular, the use of remarkably inexpensive chemical agent (NaCl) to promote the formation of cage-bell structured particles containing a wide spectrum of metal shells highlights its engineering merit to produce highly selective electrocatalysts on a large scale for the cathode reaction of direct methanol fuel cells. PMID:26578100

  19. Enhancing the methanol tolerance of platinum nanoparticles for the cathode reaction of direct methanol fuel cells through a geometric design

    NASA Astrophysics Data System (ADS)

    Feng, Yan; Ye, Feng; Liu, Hui; Yang, Jun

    2015-11-01

    Mastery over the structure of nanoparticles might be an effective way to enhance their performance for a given application. Herein we demonstrate the design of cage-bell nanostructures to enhance the methanol tolerance of platinum (Pt) nanoparticles while remaining their catalytic activity for oxygen reduction reaction. This strategy starts with the synthesis of core-shell-shell nanoparticles with Pt and silver (Ag) residing respectively in the core and inner shell regions, which are then agitated with saturated sodium chloride (NaCl) solution to eliminate the Ag component from the inner shell region, leading to the formation of bimetallic nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a metal shell with nano-channels, which exhibit superior methanol-tolerant property in catalyzing oxygen reduction reaction due to the different diffusion behaviour of methanol and oxygen in the porous metal shell of cage-bell structured nanoparticles. In particular, the use of remarkably inexpensive chemical agent (NaCl) to promote the formation of cage-bell structured particles containing a wide spectrum of metal shells highlights its engineering merit to produce highly selective electrocatalysts on a large scale for the cathode reaction of direct methanol fuel cells.

  20. Over-expression of histone H3K4 demethylase gene JMJ15 enhances salt tolerance in Arabidopsis

    PubMed Central

    Shen, Yuan; Conde e Silva, Natalia; Audonnet, Laure; Servet, Caroline; Wei, Wei; Zhou, Dao-Xiu

    2014-01-01

    Histone H3 lysine 4 trimethylation (H3K4me3) has been shown to be involved in stress-responsive gene expression and gene priming in plants. However, the role of H3K4me3 resetting in the processes is not clear. In this work we studied the expression and function of Arabidopsis H3K4 demethylase gene JMJ15. We show that the expression of JMJ15 was relatively low and was limited to a number of tissues during vegetative growth but was higher in young floral organs. Over-expression of the gene in gain-of-function mutants reduced the plant height with accumulation of lignin in stems, while the loss-of-function mutation did not produce any visible phenotype. The gain-of-function mutants showed enhanced salt tolerance, whereas the loss-of-function mutant was more sensitive to salt compared to the wild type. Transcriptomic analysis revealed that over-expression of JMJ15 down-regulated many genes which are preferentially marked by H3K4me3 and H3K4me2. Many of the down-regulated genes encode transcription regulators involved in stress responses. The data suggest that increased JMJ15 levels may regulate the gene expression program that enhances stress tolerance. PMID:25009544

  1. Silicon enhanced salt tolerance by improving the root water uptake and decreasing the ion toxicity in cucumber

    PubMed Central

    Wang, Shiwen; Liu, Peng; Chen, Daoqian; Yin, Lina; Li, Hongbing; Deng, Xiping

    2015-01-01

    Although the effects of silicon application on enhancing plant salt tolerance have been widely investigated, the underlying mechanism has remained unclear. In this study, seedlings of cucumber, a medium silicon accumulator plant, grown in 0.83 mM silicon solution for 2 weeks were exposed to 65 mM NaCl solution for another 1 week. The dry weight and shoot/root ratio were reduced by salt stress, but silicon application significantly alleviated these decreases. The chlorophyll concentration, net photosynthetic rate, transpiration rate and leaf water content were higher in plants treated with silicon than in untreated plants under salt stress conditions. Further investigation showed that salt stress decreased root hydraulic conductance (Lp), but that silicon application moderated this salt-induced decrease in Lp. The higher Lp in silicon-treated plants may account for the superior plant water balance. Moreover, silicon application significantly decreased Na+ concentration in the leaves while increasing K+ concentration. Simultaneously, both free and conjugated types of polyamines were maintained at high levels in silicon-treated plants, suggesting that polyamines may be involved in the ion toxicity. Our results indicate that silicon enhances the salt tolerance of cucumber through improving plant water balance by increasing the Lp and reducing Na+ content by increasing polyamine accumulation. PMID:26442072

  2. Enhancing the methanol tolerance of platinum nanoparticles for the cathode reaction of direct methanol fuel cells through a geometric design.

    PubMed

    Feng, Yan; Ye, Feng; Liu, Hui; Yang, Jun

    2015-01-01

    Mastery over the structure of nanoparticles might be an effective way to enhance their performance for a given application. Herein we demonstrate the design of cage-bell nanostructures to enhance the methanol tolerance of platinum (Pt) nanoparticles while remaining their catalytic activity for oxygen reduction reaction. This strategy starts with the synthesis of core-shell-shell nanoparticles with Pt and silver (Ag) residing respectively in the core and inner shell regions, which are then agitated with saturated sodium chloride (NaCl) solution to eliminate the Ag component from the inner shell region, leading to the formation of bimetallic nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a metal shell with nano-channels, which exhibit superior methanol-tolerant property in catalyzing oxygen reduction reaction due to the different diffusion behaviour of methanol and oxygen in the porous metal shell of cage-bell structured nanoparticles. In particular, the use of remarkably inexpensive chemical agent (NaCl) to promote the formation of cage-bell structured particles containing a wide spectrum of metal shells highlights its engineering merit to produce highly selective electrocatalysts on a large scale for the cathode reaction of direct methanol fuel cells. PMID:26578100

  3. Cacao liquor procyanidin extract improves glucose tolerance by enhancing GLUT4 translocation and glucose uptake in skeletal muscle.

    PubMed

    Yamashita, Yoko; Okabe, Masaaki; Natsume, Midori; Ashida, Hitoshi

    2012-01-01

    Hyperglycaemia and insulin resistance are associated with the increased risk of the metabolic syndrome and other severe health problems. The insulin-sensitive GLUT4 regulates glucose homoeostasis in skeletal muscle and adipose tissue. In this study, we investigated whether cacao liquor procyanidin (CLPr) extract, which contains epicatechin, catechin and other procyanidins, improves glucose tolerance by promoting GLUT4 translocation and enhances glucose uptake in muscle cells. Our results demonstrated that CLPr increased glucose uptake in a dose-dependent manner and promoted GLUT4 translocation to the plasma membrane of L6 myotubes. Oral administration of a single dose of CLPr suppressed the hyperglycaemic response after carbohydrate ingestion, which was accompanied by enhanced GLUT4 translocation in ICR mice. These effects of CLPr were independent of α-glucosidase inhibition in the small intestine. CLPr also promoted GLUT4 translocation in skeletal muscle of C57BL/6 mice fed a CLPr-supplemented diet for 7 d. These results indicate that CLPr is a beneficial food material for improvement of glucose tolerance by promoting GLUT4 translocation to the plasma membrane of skeletal muscle. PMID:25191549

  4. TaNAC2, a NAC-type wheat transcription factor conferring enhanced multiple abiotic stress tolerances in Arabidopsis

    PubMed Central

    Mao, Xinguo; Zhang, Hongying; Qian, Xueya; Li, Ang; Zhao, Guangyao; Jing, Ruilian

    2012-01-01

    Environmental stresses such as drought, salinity, and cold are major factors that significantly limit agricultural productivity. NAC transcription factors play essential roles in response to various abiotic stresses. However, the paucity of wheat NAC members functionally characterized to date does not match the importance of this plant as a world staple crop. Here, the function of TaNAC2 was characterized in Arabidopsis thaliana. A fragment of TaNAC2 was obtained from suppression subtractive cDNA libraries of wheat treated with polyethylene glycol, and its full-length cDNA was obtained by searching a full-length wheat cDNA library. Gene expression profiles indicated that TaNAC2 was involved in response to drought, salt, cold, and abscisic acid treatment. To test its function, transgenic Arabidopsis lines overexpressing TaNAC2–GFP controlled by the cauliflower mosaic virus 35S promoter were generated. Overexpression of TaNAC2 resulted in enhanced tolerances to drought, salt, and freezing stresses in Arabidopsis, which were simultaneously demonstrated by enhanced expression of abiotic stress-response genes and several physiological indices. Therefore, TaNAC2 has potential for utilization in transgenic breeding to improve abiotic stress tolerances in crops. PMID:22330896

  5. Highly boron deficiency-tolerant plants generated by enhanced expression of NIP5;1, a boric acid channel.

    PubMed

    Kato, Yuichi; Miwa, Kyoko; Takano, Junpei; Wada, Motoko; Fujiwara, Toru

    2009-01-01

    Boron (B) is an essential element for plants, and B deficiency is a worldwide agricultural problem. In B-deficient areas, B is often supplied as fertilizer, but excess B can be toxic to both plants and animals. Generation of B deficiency-tolerant plants could reduce B fertilizer use. Improved fertility under B-limiting conditions in Arabidopsis thaliana by overexpression of BOR1, a B transporter, has been reported, but the root growth was not improved by the BOR1 overexpression. In this study, we report that enhanced expression of NIP5;1, a boric acid channel for efficient B uptake, resulted in improved root elongation under B-limiting conditions in A. thaliana. An NIP5;1 activation tag line, which has a T-DNA insertion with enhancer sequences near the NIP5;1 gene, showed improved root elongation under B limitation. We generated a construct which mimics the tag line: the cauliflower mosaic virus 35S RNA promoter was inserted at 1,357 bp upstream of the NIP5;1 transcription initiation site. Introduction of this construct into the nip5;1-1 mutant and the BOR1 overexpresser resulted in enhanced expression of NIP5;1 and improved root elongation under low B supply. Furthermore, one of the transgenic lines exhibited improved fertility and short-term B uptake. Our results demonstrate successful improvement of B deficiency tolerance and the potential of enhancing expression of a mineral nutrient channel gene to improve growth under nutrient-limiting conditions. PMID:19017629

  6. Transformation of Synechococcus with a gene for choline oxidase enhances tolerance to salt stress.

    PubMed

    Deshnium, P; Los, D A; Hayashi, H; Mustardy, L; Murata, N

    1995-12-01

    Choline oxidase, isolated from the soil bacterium Arthrobacter globiformis, converts choline to glycinebetaine (N-trimethylglycine) without a requirement for any cofactors. The gene for this enzyme, designated codA, was cloned and introduced into the cyanobacterium Synechococcus sp. PCC 7942. The codA gene was expressed under the control of a strong constitutive promoter, and the transformed cells accumulated glycinebetaine at intracellular levels of 60-80 mM. Consequently the cells acquired tolerance to salt stress, as evaluated in terms of growth, accumulation of chlorophyll and photosynthetic activity. PMID:8555454

  7. Epigenetic regulation of spinal cord gene expression contributes to enhanced postoperative pain and analgesic tolerance subsequent to continuous opioid exposure

    PubMed Central

    Liang, De-Yong; Shi, Xiao-You; Sun, Yuan; Clark, J David

    2016-01-01

    Background Opioids have become the mainstay for treatment of moderate to severe pain and are commonly used to treat surgical pain. While opioid administration has been shown to cause opioid-induced hyperalgesia and tolerance, interactions between opioid administration and surgery with respect to these problematic adaptations have scarcely been addressed. Accumulating evidence suggests opioids and nociceptive signaling may converge on epigenetic mechanisms in spinal cord to enhance or prolong neuroplastic changes. Epigenetic regulation of Bdnf (brain-derived neurotrophic factor) and Pdyn (prodynorphin) genes may be involved. Results Four days of ascending doses of morphine treatment caused opioid-induced hyperalgesia and reduced opioid analgesic efficacy in mice. Both opioid-induced hyperalgesia and the reduced opioid analgesic efficacy were enhanced in mice that received hindpaw incisions. The expression of Bdnf and Pdyn (qPCR) was increased after morphine treatment and incision. Chromatin immunoprecipitation assays demonstrated that the Pdyn and Bdnf promoters were more strongly associated with acetylated H3K9 after morphine plus incision than in the morphine or incision alone groups. Selective tropomyosin-related kinase B (ANA-12) and κ-opioid receptor (nor-binaltorphimine) antagonists were administered intrathecally, both reduced hyperalgesia one or three days after surgery. Administration of ANA-12 or nor-binaltorphimine attenuated the decreased morphine analgesic efficacy on day 1, but only nor-binaltorphimine was effective on day 3 after incision in opioid-exposed group. Coadministration of histone acetyltransferase inhibitor anacardic acid daily with morphine blocked the development of opioid-induced hyperalgesia and attenuated incision-enhanced hyperalgesia in morphine-treated mice. Anacardic acid had similar effects on analgesic tolerance, showing the involvement of histone acetylation in the interactions detected. Conclusions Spinal epigenetic changes

  8. Enhance nisin yield via improving acid-tolerant capability of Lactococcus lactis F44

    PubMed Central

    Zhang, Jian; Caiyin, Qinggele; Feng, Wenjing; Zhao, Xiuli; Qiao, Bin; Zhao, Guangrong; Qiao, Jianjun

    2016-01-01

    Traditionally, nisin was produced industrially by using Lactococcus lactis in the neutral fermentation process. However, nisin showed higher activity in the acidic environment. How to balance the pH value for bacterial normal growth and nisin activity might be the key problem. In this study, 17 acid-tolerant genes and 6 lactic acid synthetic genes were introduced in L. lactis F44, respectively. Comparing to the 2810 IU/mL nisin yield of the original strain F44, the nisin titer of the engineered strains over-expressing hdeAB, ldh and murG, increased to 3850, 3979 and 4377 IU/mL, respectively. These engineered strains showed more stable intracellular pH value during the fermentation process. Improvement of lactate production could partly provide the extra energy for the expression of acid tolerance genes during growth. Co-overexpression of hdeAB, murG, and ldh(Z) in strain F44 resulted in the nisin titer of 4913 IU/mL. The engineered strain (ABGL) could grow on plates with pH 4.2, comparing to the surviving pH 4.6 of strain F44. The fed-batch fermentation showed nisin titer of the co-expression L. lactis strain could reach 5563 IU/mL with lower pH condition and longer cultivation time. This work provides a novel strategy of constructing robust strains for use in industry process. PMID:27306587

  9. Arabidopsis ATAF1 enhances the tolerance to salt stress and ABA in transgenic rice.

    PubMed

    Liu, Yongchang; Sun, Jie; Wu, Yaorong

    2016-09-01

    NAC (NAM, ATAF1/2, CUC2) transcription factors are plant-specific and have diverse functions in many plant developmental processes and responses to stress. In our previous study, we found that the expression of ATAF1, an Arabidopsis NAC gene, was obviously induced by high-salinity and abscisic acid (ABA). The overexpression of ATAF1 in Arabidopsis increased plant sensitivity to ABA and salt. To investigate whether ATAF1 affects the sensitivity of monocotyledon plant to salt and ABA, ATAF1 transgenic rice were generated. Transgenic rice exhibited significantly improved salt tolerance and insensitivity to ABA. The results of real-time PCR showed that ATAF1 overexpression in rice elevated the transcription of OsLEA3, OsSalT1 and OsPM1, which are stress-associated genes. Our results indicate that ATAF1 plays an important role in response to salt stress and may be utilized to improve the salt tolerance of rice. PMID:27216423

  10. Enhancement of the transverse stress tolerance of REBCO Roebel cables by epoxy impregnation

    NASA Astrophysics Data System (ADS)

    Otten, S.; Dhallé, M.; Gao, P.; Wessel, W.; Kario, A.; Kling, A.; Goldacker, W.

    2015-06-01

    REBCO Roebel cables are considered for application in high-temperature superconducting inserts for accelerator magnets because of their fully transposed geometry, high-engineering current density, and adequate bending tolerance. In these magnets the cables experience Lorentz forces leading to transverse stresses up to 100-150 MPa. Previous reports have shown bare Roebel cables to degrade under such high stresses so that additional reinforcement is required. In this work, two identical Roebel cables are vacuum impregnated with a mixture of epoxy and fused silica in order to improve their tolerance to transverse stress. After impregnation, the critical current of the cables is measured under transverse mechanical loading at T = 4.2 K, {{B}\\bot }=10.5 T. A reference cable without impregnation is tested as well. Pressures up to 350 MPa are applied to a short (30 mm) section of each cable. No degradation was observed for pressures up to 250 MPa and 170 MPa in the two impregnated cables. The critical current of the non-impregnated cable, in contrast, started to decrease at stresses as low as 40 MPa.

  11. Overexpression of Ferredoxin, PETF, Enhances Tolerance to Heat Stress in Chlamydomonas reinhardtii

    PubMed Central

    Lin, Yi-Hsien; Pan, Kui-You; Hung, Ching-Hui; Huang, Hsiang-En; Chen, Ching-Lian; Feng, Teng-Yung; Huang, Li-Fen

    2013-01-01

    Reactive oxygen species (ROS) produced by plants in adverse environments can cause damage to organelles and trigger cell death. Removal of excess ROS can be achieved through the ascorbate scavenger pathway to prevent plant cell death. The amount of this scavenger can be regulated by ferredoxin (FDX). Chloroplastic FDXs are electron transfer proteins that perform in distributing photosynthetic reducing power. In this study, we demonstrate that overexpression of the endogenous photosynthetic FDX gene, PETF, in Chlamydomonas reinhardtii could raise the level of reduced ascorbate and diminish H2O2 levels under normal growth conditions. Furthermore, the overexpressing PETF transgenic Chlamydomonas lines produced low levels of H2O2 and exhibited protective effects that were observed through decreased chlorophyll degradation and increased cell survival under heat-stress conditions. The findings of this study suggest that overexpression of PETF can increase the efficiency of ROS scavenging in chloroplasts to confer heat tolerance. The roles of PETF in the downregulation of the ROS level offer a method for potentially improving the tolerance of crops against heat stress. PMID:24141188

  12. Enhance nisin yield via improving acid-tolerant capability of Lactococcus lactis F44.

    PubMed

    Zhang, Jian; Caiyin, Qinggele; Feng, Wenjing; Zhao, Xiuli; Qiao, Bin; Zhao, Guangrong; Qiao, Jianjun

    2016-01-01

    Traditionally, nisin was produced industrially by using Lactococcus lactis in the neutral fermentation process. However, nisin showed higher activity in the acidic environment. How to balance the pH value for bacterial normal growth and nisin activity might be the key problem. In this study, 17 acid-tolerant genes and 6 lactic acid synthetic genes were introduced in L. lactis F44, respectively. Comparing to the 2810 IU/mL nisin yield of the original strain F44, the nisin titer of the engineered strains over-expressing hdeAB, ldh and murG, increased to 3850, 3979 and 4377 IU/mL, respectively. These engineered strains showed more stable intracellular pH value during the fermentation process. Improvement of lactate production could partly provide the extra energy for the expression of acid tolerance genes during growth. Co-overexpression of hdeAB, murG, and ldh(Z) in strain F44 resulted in the nisin titer of 4913 IU/mL. The engineered strain (ABGL) could grow on plates with pH 4.2, comparing to the surviving pH 4.6 of strain F44. The fed-batch fermentation showed nisin titer of the co-expression L. lactis strain could reach 5563 IU/mL with lower pH condition and longer cultivation time. This work provides a novel strategy of constructing robust strains for use in industry process. PMID:27306587

  13. Overexpression of SmLEA enhances salt and drought tolerance in Escherichia coli and Salvia miltiorrhiza.

    PubMed

    Wu, Yucui; Liu, Congling; Kuang, Jing; Ge, Qian; Zhang, Yuan; Wang, Zhezhi

    2014-09-01

    Salinity and drought are important abiotic stresses limiting plant growth and development. Late embryogenesis abundant (LEA) proteins are a group of proteins associated with tolerance to water-related stress. We previously cloned an LEA gene, SmLEA, from Salvia miltiorrhiza Bunge. Phylogenetic analysis indicated that SmLEA belongs to Group LEA14, which is involved in the dehydration response. To determine its function in detail, we have now overexpressed SmLEA in Escherichia coli and S. miltiorrhiza. The logarithmic increase in accumulations of SmLEA proteins in E. coli occurred earlier under salinity than under standard conditions. SmLEA-transformed S. miltiorrhiza plants also showed faster root elongation and a lower malondialdehyde concentration than the empty vector control plants did when cultured on MS media supplemented with 60 mM NaCl or 150 mM mannitol. Moreover, SmLEA-overexpressing transgenics experienced a less rapid rate of water loss. Under either salinity or drought, overexpressing plants had greater superoxide dismutase activity and a higher glutathione concentration. These results suggest that SmLEA may be useful in efforts to improve drought and salinity tolerance in S. miltiorrhiza. Our data also provide a good foundation for further studies into the stress resistance mechanism and molecular breeding of this valuable medicinal plant. PMID:24595620

  14. Overexpression of ferredoxin, PETF, enhances tolerance to heat stress in Chlamydomonas reinhardtii.

    PubMed

    Lin, Yi-Hsien; Pan, Kui-You; Hung, Ching-Hui; Huang, Hsiang-En; Chen, Ching-Lian; Feng, Teng-Yung; Huang, Li-Fen

    2013-01-01

    Reactive oxygen species (ROS) produced by plants in adverse environments can cause damage to organelles and trigger cell death. Removal of excess ROS can be achieved through the ascorbate scavenger pathway to prevent plant cell death. The amount of this scavenger can be regulated by ferredoxin (FDX). Chloroplastic FDXs are electron transfer proteins that perform in distributing photosynthetic reducing power. In this study, we demonstrate that overexpression of the endogenous photosynthetic FDX gene, PETF, in Chlamydomonas reinhardtii could raise the level of reduced ascorbate and diminish H2O2 levels under normal growth conditions. Furthermore, the overexpressing PETF transgenic Chlamydomonas lines produced low levels of H2O2 and exhibited protective effects that were observed through decreased chlorophyll degradation and increased cell survival under heat-stress conditions. The findings of this study suggest that overexpression of PETF can increase the efficiency of ROS scavenging in chloroplasts to confer heat tolerance. The roles of PETF in the downregulation of the ROS level offer a method for potentially improving the tolerance of crops against heat stress. PMID:24141188

  15. Enhanced gastric tolerability and improved anti-obesity effect of capsaicinoids-loaded PCL microparticles.

    PubMed

    Almeida, Martinha A; Nadal, Jessica M; Grassiolli, Sabrina; Paludo, Katia S; Zawadzki, Sônia F; Cruz, Letícia; Paula, Josiane P; Farago, Paulo V

    2014-07-01

    Capsaicinoids show several pharmacological effects including weight loss. However, their pungency limits the long-term use through the gastrointestinal tract. In that sense, the goal of this study was to prepare capsaicinoids-loaded poly(ε-caprolactone) microparticles as an oral carrier in order to improve their gastric tolerability and to make feasible the long-term treatment of obesity. Formulations containing 3, 5 and 10% capsaicinoids were successfully obtained by simple emulsion/solvent evaporation method. Values of encapsulation efficiency above 90% were achieved. Microparticles showed spherical shape and smooth surface. The particle size was suitable for oral use in order to provide an extended release through the gastrointestinal tract. No chemical bond was observed between drug and polymer. Microencapsulation led to drug amorphization. Formulations prolonged the release of capsaicinoids without changing the release kinetic (biexponential model). Microencapsulation increased the gastric tolerability of capsaicinoids because it prevented inflammatory processes in the stomach of rats. Microparticles containing 5% capsaicinoids demonstrated a statistically significant reduction of Lee index, mesenteric and retroperitoneal fat pads of rats with obesity induced by hypothalamic lesion using monosodium l-glutamate. In summary, capsaicinoids-loaded poly(ε-caprolactone) microparticles are low-irritative oral controlled-release carriers for a long-term use in obesity. PMID:24857502

  16. Tetraploid Rangpur lime rootstock increases drought tolerance via enhanced constitutive root abscisic acid production.

    PubMed

    Allario, Thierry; Brumos, Javier; Colmenero-Flores, Jose M; Iglesias, Domingo J; Pina, Jose A; Navarro, Luis; Talon, Manuel; Ollitrault, Patrick; Morillon, Raphaël

    2013-04-01

    Whole-genome duplication, or polyploidy, is common in many plant species and often leads to better adaptation to adverse environmental condition. However, little is known about the physiological and molecular determinants underlying adaptation. We examined the drought tolerance in diploid (2x) and autotetraploid (4x) clones of Rangpur lime (Citrus limonia) rootstocks grafted with 2x Valencia Delta sweet orange (Citrus sinensis) scions, named V/2xRL and V/4xRL, respectively. Physiological experiments to study root-shoot communication associated with gene expression studies in roots and leaves were performed. V/4xRL was much more tolerant to water deficit than V/2xRL. Gene expression analysis in leaves and roots showed that more genes related to the response to water stress were differentially expressed in V/2xRL than in V/4xRL. Prior to the stress, when comparing V/4xRL to V/2xRL, V/4xRL leaves had lower stomatal conductance and greater abscisic acid (ABA) content. In roots, ABA content was higher in V/4xRL and was associated to a greater expression of drought responsive genes, including CsNCED1, a pivotal regulatory gene of ABA biosynthesis. We conclude that tetraploidy modifies the expression of genes in Rangpur lime citrus roots to regulate long-distance ABA signalling and adaptation to stress. PMID:23050986

  17. Overexpression of NaKR3 enhances salt tolerance in Arabidopsis.

    PubMed

    Luo, Q; Zhao, Z; Li, D K; Zhang, Y; Xie, L F; Peng, M F; Yuan, S; Yang, Y

    2016-01-01

    Salinity is a major abiotic stress in agriculture. Here, we report that SODIUM POTASSIUM ROOT DEFECTIVE3 (NaKR3), which encodes a heavy metal-associated domain protein, is involved in salt tolerance in Arabidopsis. The results of quantitative reverse transcription-polymerase chain reaction analysis revealed that NaKR3 was induced by high salinity and osmotic stresses, but not by Cu(2+) stress. Transient expression of NaKR3-GFP in Arabidopsis protoplasts showed that the NaKR3 protein was localized in the cytosol. Transgenic Arabidopsis plants constitutively expressing NaKR3 under the control of the cauliflower mosaic virus 35S promoter exhibited increased tolerance to salt treatment. Furthermore, overexpression of NaKR3 increased the expression of SOS1 and SOS3, but decreased the accumulation of salt-induced proline. Taken together, our results indicate that NaKR3 is involved in the salt stress response in Arabidopsis. PMID:26909945

  18. Eucalyptus tolerance mechanisms to lanthanum and cerium: subcellular distribution, antioxidant system and thiol pools.

    PubMed

    Shen, Yichang; Zhang, Shirong; Li, Sen; Xu, Xiaoxun; Jia, Yongxia; Gong, Guoshu

    2014-12-01

    Guanglin 9 (Eucalyptus grandis × Eucalyptus urophlla) and Eucalyptus grandis 5 are two eucalyptus species which have been found to grow normally in soils contaminated with lanthanum and cerium, but the tolerance mechanisms are not clear yet. In this study, a pot experiment was conducted to investigate the tolerance mechanisms of the eucalyptus to lanthanum and cerium. Cell walls stored 45.40-63.44% of the metals under lanthanum or cerium stress. Peroxidase and catalase activities enhanced with increasing soil La or Ce concentrations up to 200 mg kg(-1), while there were no obvious changes in glutathione and ascorbate concentrations. Non-protein thiols concentrations increased with increasing treatment levels up to 200 mg kg(-1), and then decreased. Phytochelatins concentrations continued to increase under La or Ce stress. Therefore, the two eucalyptus species are La and Ce tolerant plants, and the tolerance mechanisms include cell wall deposition, antioxidant system response, and thiol compound synthesis. PMID:25303462

  19. Inducible and constitutive expression of an elicitor gene Hrip1 from Alternaria tenuissima enhances stress tolerance in Arabidopsis.

    PubMed

    Peng, Xue-Cong; Qiu, De-Wen; Zeng, Hong-Mei; Guo, Li-Hua; Yang, Xiu-Fen; Liu, Zheng

    2015-02-01

    Hrip1 is a novel hypersensitive response-inducing protein secreted by Alternaria tenuissima that activates defense responses and systemic acquired resistance in tobacco. This study investigates the role that Hrip1 plays in responses to abiotic and biotic stress using transgenic Arabidopsis thaliana expressing the Hrip1 gene under the control of the stress-inducible rd29A promoter or constitutive cauliflower mosaic virus 35S promoter. Bioassays showed that inducible Hrip1 expression in rd29A∷Hrip1 transgenic lines had a significantly higher effect on plant height, silique length, plant dry weight, seed germination and root length under salt and drought stress compared to expression in 35S∷Hrip1 lines and wild type plants. The level of enhancement of resistance to Botrytis cinerea by the 35S∷Hrip1 lines was higher than in the rd29A∷Hrip1 lines. Moreover, stress-related gene expression in the transgenic Arabidopsis lines was significantly increased by 200 mM NaCl and 200 mM mannitol treatments, and defense genes in the jasmonic acid and ethylene signaling pathway were significantly up-regulated after Botrytis inoculation in the Hrip1 transgenic plants. Furthermore, the activity of some antioxidant enzymes, such as peroxidase and catalase increased after salt and drought stress and Botrytis infection. These results suggested that the Hrip1 protein contributes to abiotic and biotic resistance in transgenic Arabidopsis and may be used as a useful gene for resistance breeding in crops. Although the constitutive expression of Hrip1 is suitable for biotic resistance, inducible Hrip1 expression is more responsive for abiotic resistance. PMID:25120219

  20. Overexpression of OsHMA3 enhances Cd tolerance and expression of Zn transporter genes in rice

    PubMed Central

    Sasaki, Akimasa; Yamaji, Naoki; Ma, Jian Feng

    2014-01-01

    As a member of the heavy metal ATPase (HMA) family, OsHMA3 is a tonoplast-localized transporter for Cd in the roots of rice (Oryza sativa). Overexpression of OsHMA3 selectively reduces Cd accumulation in the grain. Further characterization in the present study revealed that overexpression of OsHMA3 also enhances the tolerance to toxic Cd. The growth of both the roots and shoots was similar in the absence of Cd between an OsHMA3-overexpressed line and vector control, but the Cd-inhibited growth was significantly alleviated in the OsHMA3-overexpressed line. The overexpressed line showed higher Cd concentration in the roots, but lower Cd concentration in the shoots compared with the wild-type rice and vector control line, indicating that overexpression of OsHMA3 enhanced vacuolar sequestration of Cd in the roots. The Zn concentration in the roots of the OsHMA3-overexpressed line was constantly higher than that of vector control, but the Zn concentration in the shoots was similar between the overexpressed line and vector control. Five transporter genes belonging to the ZIP family were constitutively up-regulated in the OsHMA3-overexpressed line. These results suggest that shoot Zn level was maintained by up-regulating these genes involved in the Zn uptake/translocation. Taken together, overexpression of OsHMA3 is an efficient way to reduce Cd accumulation in the grain and to enhance Cd tolerance in rice. PMID:25151617

  1. Enhancement of tolerance development to morphine in rats prenatally exposed to morphine, methadone, and buprenorphine

    PubMed Central

    2010-01-01

    Background Abuse of addictive substances is a serious problem that has a significant impact on areas such as health, the economy, and public safety. Heroin use among young women of reproductive age has drawn much attention around the world. However, there is a lack of information on effects of prenatal exposure to opioids on their offspring. In this study, an animal model was established to study effects of prenatal exposure to opioids on offspring. Methods Female pregnant Sprague-Dawley rats were sub-grouped to receive (1) vehicle, (2) 2-4 mg/kg morphine (1 mg/kg increment per week), (3) 7 mg/kg methadone, and (4) 3 mg/kg buprenorphine, subcutaneously, once or twice a day from E3 to E20. The experiments were conducted on animals 8-12 weeks old and with body weight between 250 and 350 g. Results Results showed that prenatal exposure to buprenorphine caused higher mortality than other tested substance groups. Although we observed a significantly lower increase in body weight in all of the opioid-administered dams, the birth weight of the offspring was not altered in all treated groups. Moreover, no obvious behavioral abnormality or body-weight difference was noted during the growing period (8-12 weeks) in all offspring. When the male offspring received morphine injection twice a day for 4 days, the prenatally opioid-exposed rats more quickly developed a tolerance to morphine (as shown by the tail-flick tests), most notably the prenatally buprenorphine-exposed offspring. However, the tolerance development to methadone or buprenorphine was not different in offspring exposed prenatally to methadone or buprenorphine, respectively, when compared with that of the vehicle controlled group. Similar results were also obtained in the female animals. Conclusions Animals prenatally exposed to morphine, methadone, or buprenorphine developed tolerance to morphine faster than their controlled mates. In our animal model, prenatal exposure to buprenorphine also resulted in higher

  2. Engineering Ascorbate Peroxidase Activity Into Cytochrome C Peroxidase

    SciTech Connect

    Meharenna, Y.T.; Oertel, P.; Bhaskar, B.; Poulos, T.L.

    2009-05-26

    Cytochrome c peroxidase (CCP) and ascorbate peroxidase (APX) have very similar structures, and yet neither CCP nor APX exhibits each others activities with respect to reducing substrates. APX has a unique substrate binding site near the heme propionates where ascorbate H-bonds with a surface Arg and one heme propionate (Sharp et al. (2003) Nat. Struct. Biol. 10, 303--307). The corresponding region in CCP has a much longer surface loop, and the critical Arg residue that is required for ascorbate binding in APX is Asn in CCP. In order to convert CCP into an APX, the ascorbate-binding loop and critical arginine were engineered into CCP to give the CCP2APX mutant. The mutant crystal structure shows that the engineered site is nearly identical to that found in APX. While wild-type CCP shows no APX activity, CCP2APX catalyzes the peroxidation of ascorbate at a rate of {approx}12 min{sup -1}, indicating that the engineered ascorbate-binding loop can bind ascorbate.

  3. Brassica RNA binding protein ERD4 is involved in conferring salt, drought tolerance and enhancing plant growth in Arabidopsis.

    PubMed

    Rai, Archana N; Tamirisa, Srinath; Rao, K V; Kumar, Vinay; Suprasanna, P

    2016-03-01

    'Early responsive to dehydration' (ERD) genes are a group of plant genes having functional roles in plant stress tolerance and development. In this study, we have isolated and characterized a Brassica juncea 'ERD' gene (BjERD4) which encodes a novel RNA binding protein. The expression pattern of ERD4 analyzed under different stress conditions showed that transcript levels were increased with dehydration, sodium chloride, low temperature, heat, abscisic acid and salicylic acid treatments. The BjERD4 was found to be localized in the chloroplasts as revealed by Confocal microscopy studies. To study the function, transgenic Arabidopsis plants were generated and analyzed for various morphological and physiological parameters. The overexpressing transgenic lines showed significant increase in number of leaves with more leaf area and larger siliques as compared to wild type plants, whereas RNAi:ERD4 transgenic lines showed reduced leaf number, leaf area, dwarf phenotype and delayed seed germination. Transgenic Arabidopsis plants overexpressing BjERD4 gene also exhibited enhanced tolerance to dehydration and salt stresses, while the knockdown lines were susceptible as compared to wild type plants under similar stress conditions. It was observed that BjERD4 protein could bind RNA as evidenced by the gel-shift assay. The overall results of transcript analysis, RNA gel-shift assay, and transgenic expression, for the first time, show that the BjERD4 is involved in abiotic stress tolerance besides offering new clues about the possible roles of BjERD4 in plant growth and development. PMID:26711633

  4. Populus euphratica APYRASE2 Enhances Cold Tolerance by Modulating Vesicular Trafficking and Extracellular ATP in Arabidopsis Plants.

    PubMed

    Deng, Shurong; Sun, Jian; Zhao, Rui; Ding, Mingquan; Zhang, Yinan; Sun, Yuanling; Wang, Wei; Tan, Yeqing; Liu, Dandan; Ma, Xujun; Hou, Peichen; Wang, Meijuan; Lu, Cunfu; Shen, Xin; Chen, Shaoliang

    2015-09-01

    Apyrase and extracellular ATP play crucial roles in mediating plant growth and defense responses. In the cold-tolerant poplar, Populus euphratica, low temperatures up-regulate APYRASE2 (PeAPY2) expression in callus cells. We investigated the biochemical characteristics of PeAPY2 and its role in cold tolerance. We found that PeAPY2 predominantly localized to the plasma membrane, but punctate signals also appeared in the endoplasmic reticulum and Golgi apparatus. PeAPY2 exhibited broad substrate specificity, but it most efficiently hydrolyzed purine nucleotides, particularly ATP. PeAPY2 preferred Mg(2+) as a cofactor, and it was insensitive to various, specific ATPase inhibitors. When PeAPY2 was ectopically expressed in Arabidopsis (Arabidopsis thaliana), cold tolerance was enhanced, based on root growth measurements and survival rates. Moreover, under cold stress, PeAPY2-transgenic plants maintained plasma membrane integrity and showed reduced cold-elicited electrolyte leakage compared with wild-type plants. These responses probably resulted from efficient plasma membrane repair via vesicular trafficking. Indeed, transgenic plants showed accelerated endocytosis and exocytosis during cold stress and recovery. We found that low doses of extracellular ATP accelerated vesicular trafficking, but high extracellular ATP inhibited trafficking and reduced cell viability. Cold stress caused significant increases in root medium extracellular ATP. However, under these conditions, PeAPY2-transgenic lines showed greater control of extracellular ATP levels than wild-type plants. We conclude that Arabidopsis plants that overexpressed PeAPY2 could increase membrane repair by accelerating vesicular trafficking and hydrolyzing extracellular ATP to avoid excessive, cold-elicited ATP accumulation in the root medium and, thus, reduced ATP-induced inhibition of vesicular trafficking. PMID:26224801

  5. Populus euphratica APYRASE2 Enhances Cold Tolerance by Modulating Vesicular Trafficking and Extracellular ATP in Arabidopsis Plants1[OPEN

    PubMed Central

    Deng, Shurong; Sun, Jian; Zhao, Rui; Ding, Mingquan; Zhang, Yinan; Sun, Yuanling; Wang, Wei; Tan, Yeqing; Liu, Dandan; Ma, Xujun; Hou, Peichen; Wang, Meijuan; Lu, Cunfu; Shen, Xin; Chen, Shaoliang

    2015-01-01

    Apyrase and extracellular ATP play crucial roles in mediating plant growth and defense responses. In the cold-tolerant poplar, Populus euphratica, low temperatures up-regulate APYRASE2 (PeAPY2) expression in callus cells. We investigated the biochemical characteristics of PeAPY2 and its role in cold tolerance. We found that PeAPY2 predominantly localized to the plasma membrane, but punctate signals also appeared in the endoplasmic reticulum and Golgi apparatus. PeAPY2 exhibited broad substrate specificity, but it most efficiently hydrolyzed purine nucleotides, particularly ATP. PeAPY2 preferred Mg2+ as a cofactor, and it was insensitive to various, specific ATPase inhibitors. When PeAPY2 was ectopically expressed in Arabidopsis (Arabidopsis thaliana), cold tolerance was enhanced, based on root growth measurements and survival rates. Moreover, under cold stress, PeAPY2-transgenic plants maintained plasma membrane integrity and showed reduced cold-elicited electrolyte leakage compared with wild-type plants. These responses probably resulted from efficient plasma membrane repair via vesicular trafficking. Indeed, transgenic plants showed accelerated endocytosis and exocytosis during cold stress and recovery. We found that low doses of extracellular ATP accelerated vesicular trafficking, but high extracellular ATP inhibited trafficking and reduced cell viability. Cold stress caused significant increases in root medium extracellular ATP. However, under these conditions, PeAPY2-transgenic lines showed greater control of extracellular ATP levels than wild-type plants. We conclude that Arabidopsis plants that overexpressed PeAPY2 could increase membrane repair by accelerating vesicular trafficking and hydrolyzing extracellular ATP to avoid excessive, cold-elicited ATP accumulation in the root medium and, thus, reduced ATP-induced inhibition of vesicular trafficking. PMID:26224801

  6. On the design of fault-tolerant two-dimensional systolic arrays for yield enhancement

    SciTech Connect

    Kim, J.H.; Reddy, S.M.

    1989-04-01

    The continuing growth of interest in systolic arrays poses the problem of ensuring an acceptable yield. In this paper, the authors propose a unified approach to the design of fault-tolerant systolic arrays incorporating design for testability, a testing scheme, a reconfiguration algorithm, time complexity analysis of the proposed reconfiguration algorithm, and yield analysis. A main feature of the proposed designs is that multiple PE's in a 2-D array can be tested simultaneously, thus reducing the testing time significantly. Another feature is that with introduction of delay registers, the proposed reconfiguration algorithm reconfigures a faulty 2-D systolic array into a fault-free array without reducing throughput. The overall aim of this paper is to provide a design for a 2-D systolic array that produces high yield in VLSI/WSI implementations.

  7. Populus euphratica HSF binds the promoter of WRKY1 to enhance salt tolerance.

    PubMed

    Shen, Zedan; Yao, Jun; Sun, Jian; Chang, Liwei; Wang, Shaojie; Ding, Mingquan; Qian, Zeyong; Zhang, Huilong; Zhao, Nan; Sa, Gang; Hou, Peichen; Lang, Tao; Wang, Feifei; Zhao, Rui; Shen, Xin; Chen, Shaoliang

    2015-06-01

    Poplar species increase expressions of transcription factors to deal with salt environments. We assessed the salt-induced transcriptional responses of heat-shock transcription factor (HSF) and WRKY1 in Populus euphratica, and their roles in salt tolerance. High NaCl (200mM) induced PeHSF and PeWRKY1 expressions in P. euphratica, with a rapid rise in roots than in leaves. Moreover, the salt-elicited PeHSF reached its peak level 6h earlier than PeWRKY1 in leaves. PeWRKY1 was down-regulated in salinized P. euphratica when PeHSF was silenced by tobacco rattle virus-based gene silencing. Subcellular assays in onion epidermal cells and Arabidopsis protoplasts revealed that PeHSF and PeWRKY1 were restricted to the nucleus. Transgenic tobacco plants overexpressing PeWRKY1 showed improved salt tolerance in terms of survival rate, root growth, photosynthesis, and ion fluxes. We further isolated an 1182-bp promoter fragment upstream of the translational start of PeWRKY1 from P. euphratica. Promoter sequence analysis revealed that PeWRKY1 harbours four tandem repeats of heat shock element (HSE) in the upstream regulatory region. Yeast one-hybrid assay showed that PeHSF directly binds the cis-acting HSE. To determine whether the HSE cluster was important for salt-induced PeWRKY1 expression, the promoter-reporter construct PeWRKY1-pro::GUS was transferred to tobacco plants. β-glucuronidase activities increased in root, leaf, and stem tissues under salt stress. Therefore, we conclude that salinity increased PeHSF transcription in P. euphratica, and that PeHSF binds the cis-acting HSE of the PeWRKY1 promoter, thus activating PeWRKY1 expression. PMID:25900569

  8. Chromate-tolerant bacteria for enhanced metal uptake by Eichhornia crassipes (Mart.).

    PubMed

    Abou-Shanab, R A I; Angle, J S; van Berkum, P

    2007-01-01

    A total of 85 chromate-resistant bacteria were isolated from the rhizosphere of water hyacinth grown in Mariout Lake, Egypt, as well as the sediment and water of this habitat. Only 4 (11%), 2 (8%), and 2 (8%) of isolates from each of the environments, respectively, were able to tolerate 200 mg Cr (VI) L(-1). When these eight isolates were tested for their ability to tolerate other metals or to reduce chromate, they were shown to also be resistant to Zn, Mn, and Pb, and to display different degrees of chromate reduction (28% to 95%) under aerobic conditions. The isolates with the higher chromate reduction rates from 42% to 95%, (RA1, RA2, RA3, RA5, RA7, and RA8) were genetically diverse according to RAPD analysis using four differentprimers. Bacterial isolates RA1, RA2, RA3, RAS, and RA8 had 16 S rRNA gene sequences that were most similar to Pseudomonas diminuta, Brevundimonas diminuta, Nitrobacteria irancium, Ochrobactrum anthropi, and Bacillus cereus, respectively. Water hyacinth inoculated with RA5 and RA8 increased Mn accumulation in roots by 2.4- and 1.2-fold, respectively, compared to uninoculated controls. The highest concentrations of Cr (0.4 g kg(-1)) and Zn (0.18 g kg(-1)) were accumulated in aerial portions of water hyacinth inoculated with RA3. Plants inoculated with RA1, RA2, RA3, RA5, RA7, and RA8 had 7-, 11-, 24-, 29-, 35-, and 21-fold, respectively, higher Cr concentrations in roots compared to the control. These bacterial isolates are potential candidates in phytoremediation for chromium removal. PMID:18246718

  9. Cadmium tolerance and accumulation of Althaea rosea Cav. and its potential as a hyperaccumulator under chemical enhancement.

    PubMed

    Liu, Jia Nv; Zhou, Qi Xing; Wang, Song; Sun, Ting

    2009-02-01

    The role of ornamental plants has drawn much attention as the urban pollution levels exacerbate. Althaea rosea Cav. had showed its strong tolerance and accumulation ability of Cd in our previous work, thus, the effects of ethylenediamine triacetic acid (EDTA), ethylenegluatarotriacetic acid (EGTA) and sodium dodecyl sulfate (SDS) on its Cd phytoremediation capacity were further investigated in this work. It reconfirmed that the species had strong tolerance and accumulation ability of Cd. Particularly, the species can be regarded as a potential Cd-hyperaccumulator through applying chemical agents. However, different chelators and surfactants had great differences in affecting hyperaccumulating characteristics of the species. EGTA and SDS could not only increase the dry biomass of the plants, but also promote Cd accumulation in shoots and roots. On the contrary, EDTA was toxic to the species by restraining the growth of plants, although it could promote Cd accumulation in shoots and roots of the plants to a certain extent. Thus, EGTA and SDS were effective in enhancing phytoremediation with Althaea rosea Cav. for Cd contaminated soils, while EDTA is ineffective in this regard. PMID:18259884

  10. Heterologous expression of antifreeze protein gene AnAFP from Ammopiptanthus nanus enhances cold tolerance in Escherichia coli and tobacco.

    PubMed

    Deng, Long-Qun; Yu, Hao-Qiang; Liu, Yan-Ping; Jiao, Pei-Pei; Zhou, Shu-Feng; Zhang, Su-Zhi; Li, Wan-Chen; Fu, Feng-Ling

    2014-04-10

    Antifreeze proteins are a class of polypeptides produced by certain animals, plants, fungi and bacteria that permit their survival under the subzero environments. Ammopiptanthus nanus is the unique evergreen broadleaf bush endemic to the Mid-Asia deserts. It survives at the west edge of the Tarim Basin from the disappearance of the ancient Mediterranean in the Tertiary Period. Its distribution region is characterized by the arid climate and extreme temperatures, where the extreme temperatures range from -30 °C to 40 °C. In the present study, the antifreeze protein gene AnAFP of A. nanus was used to transform Escherichia coli and tobacco, after bioinformatics analysis for its possible function. The transformed E. coli strain expressed the heterologous AnAFP gene under the induction of isopropyl β-D-thiogalactopyranoside, and demonstrated significant enhancement of cold tolerance. The transformed tobacco lines expressed the heterologous AnAFP gene in response to cold stress, and showed a less change of relative electrical conductivity under cold stress, and a less wilting phenotype after 16 h of -3 °C cold stress and thawing for 1h than the untransformed wild-type plants. All these results imply the potential value of the AnAFP gene to be used in genetic modification of commercially important crops for improvement of cold tolerance. PMID:24502990

  11. Overexpression of a Soybean Ariadne-Like Ubiquitin Ligase Gene GmARI1 Enhances Aluminum Tolerance in Arabidopsis

    PubMed Central

    Zhang, Xiaolian; Wang, Ning; Chen, Pei; Gao, Mengmeng; Liu, Juge; Wang, Yufeng; Zhao, Tuanjie; Li, Yan; Gai, Junyi

    2014-01-01

    Ariadne (ARI) subfamily of RBR (Ring Between Ring fingers) proteins have been found as a group of putative E3 ubiquitin ligases containing RING (Really Interesting New Gene) finger domains in fruitfly, mouse, human and Arabidopsis. Recent studies showed several RING-type E3 ubiquitin ligases play important roles in plant response to abiotic stresses, but the function of ARI in plants is largely unknown. In this study, an ariadne-like E3 ubiquitin ligase gene was isolated from soybean, Glycine max (L.) Merr., and designated as GmARI1. It encodes a predicted protein of 586 amino acids with a RBR supra-domain. Subcellular localization studies using Arabidopsis protoplast cells indicated GmARI protein was located in nucleus. The expression of GmARI1 in soybean roots was induced as early as 2–4 h after simulated stress treatments such as aluminum, which coincided with the fact of aluminum toxicity firstly and mainly acting on plant roots. In vitro ubiquitination assay showed GmARI1 protein has E3 ligase activity. Overexpression of GmARI1 significantly enhanced the aluminum tolerance of transgenic Arabidopsis. These findings suggest that GmARI1 encodes a RBR type E3 ligase, which may play important roles in plant tolerance to aluminum stress. PMID:25364908

  12. Molecular characterization of the lignin-forming peroxidase: Role in growth, development and response to stress. Progress summary report, April 1, 1993--March 31, 1994

    SciTech Connect

    Lagrimini, L.M.

    1994-05-01

    Our group continues to focus on the characterization of the tobacco anionic peroxidase and its genes. Throughout this past year we have generated transgenic plants expressing {beta}-glucuronidase under control of the anionic peroxidase promoter, characterized effectors of peroxidase gene expression in transformed protoplasts, generated numerous transgenic plants which over- and under-express the anionic peroxidase in a tissue specific manner, characterized the role of the anionic peroxidase in the metabolism of auxin, introduced a marker (flag) into the anionic peroxidase primary protein sequence which will permit the identification of the recombinant protein in plant tissue, and described the enhancement of insect resistance as a result of over-expression of the anionic peroxidase. Although our research program has continued along the lines of the original proposal, we have redirected a significant effort to the role which this enzyme plays in the metabolism of auxin, and conversely, the role which auxin plays in regulating the expression of the anionic peroxidase gene.

  13. Screening Actinomycetes for Extracellular Peroxidase Activity

    PubMed Central

    Mercer, D. K.; Iqbal, M.; Miller, P.; McCarthy, A. J.

    1996-01-01

    A diverse collection of actinomycete strains were screened for production of extracellular peroxidase activity by adapting a chemiluminescence analysis system developed for horseradish peroxidase-based enzyme-linked immunosorbent assay. Extracellular peroxidase activity was found to be common but quantitatively variable, and this rapid and sensitive screening system permitted identification of a small group of high-producing strains. A range of spectrophotometric assays were compared for the measurement of peroxidase activity in concentrated culture supernatants of two selected thermophilic streptomycetes. Of these, the peroxide-dependent oxidation of 2,4-dichlorophenol was identified as the most robust and reproducible assay for quantitative studies. PMID:16535344

  14. Xenobiotics enhance laccase activity in alkali-tolerant γ-proteobacterium JB

    PubMed Central

    Singh, Gursharan; Batish, Mona; Sharma, Prince; Capalash, Neena

    2009-01-01

    Various genotoxic textile dyes, xenobiotics, substrates (10 µM) and agrochemicals (100 µg/ml) were tested for enhancement of alkalophilic laccase activity in γ-proteobacterium JB. Neutral Red, Indigo Carmine, Naphthol Base Bordears and Sulphast Ruby dyes increased the activity by 3.7, 2.7, 2.6 and 2.3 fold respectively. Xenobiotics/substrates like p-toluidine, 8-hydroxyquinoline and anthracine increased it by 3.4, 2.8 and 2.3 fold respectively. Atrazine and trycyclozole pesticides enhanced the activity by 1.95 and 1.5 fold respectively. PMID:24031313

  15. Catalase and glutathione peroxidase mimics

    PubMed Central

    Day, Brian J.

    2009-01-01

    Overproduction of the reactive oxygen species (ROS) superoxide (O2−) and hydrogen peroxide (H2O2) are increasingly implicated in human disease and aging. ROS are also being explored as important modulating agents in a number of cell signaling pathways. Earlier work has focused on development of small catalytic scavengers of O2−, commonly referred to as superoxide dismutase (SOD) mimetics. Many of these compounds also have substantial abilities to catalytically scavenge H2O2 and peroxynitrite (ONOO−). Peroxides have been increasingly shown to disrupt cell signaling cascades associated with excessive inflammation associated with a wide variety of human diseases. Early studies with enzymatic scavengers like SOD frequently reported little or no beneficial effect in biologic models unless SOD was combined with catalase or a peroxidase. Increasing attention has been devoted to developing catalase or peroxidase mimetics as a way to treat overt inflammation associated with the pathophysiology of many human disorders. This review will focus on recent development of catalytic scavengers of peroxides and their potential use as therapeutic agents for pulmonary, cardiovascular, neurodegenerative and inflammatory disorders. PMID:18948086

  16. Soybean Salt Tolerance 1 (GmST1) Reduces ROS Production, Enhances ABA Sensitivity, and Abiotic Stress Tolerance in Arabidopsis thaliana

    PubMed Central

    Ren, Shuxin; Lyle, Chimera; Jiang, Guo-liang; Penumala, Abhishek

    2016-01-01

    Abiotic stresses, including high soil salinity, significantly reduce crop production worldwide. Salt tolerance in plants is a complex trait and is regulated by multiple mechanisms. Understanding the mechanisms and dissecting the components on their regulatory pathways will provide new insights, leading to novel strategies for the improvement of salt tolerance in agricultural and economic crops of importance. Here we report that soybean salt tolerance 1, named GmST1, exhibited strong tolerance to salt stress in the Arabidopsis transgenic lines. The GmST1-overexpressed Arabidopsis also increased sensitivity to ABA and decreased production of reactive oxygen species under salt stress. In addition, GmST1 significantly improved drought tolerance in Arabidopsis transgenic lines. GmST1 belongs to a 3-prime part of Glyma.03g171600 gene in the current version of soybean genome sequence annotation. However, comparative reverse transcription-polymerase chain reaction analysis around Glyma.03g171600 genomic region confirmed that GmST1 might serve as an intact gene in soybean leaf tissues. Unlike Glyma.03g171600 which was not expressed in leaves, GmST1 was strongly induced by salt treatment in the leaf tissues. By promoter analysis, a TATA box was detected to be positioned close to GmST1 start codon and a putative ABRE and a DRE cis-acting elements were identified at about 1 kb upstream of GmST1 gene. The data also indicated that GmST1-transgenic lines survived under drought stress and showed a significantly lower water loss than non-transgenic lines. In summary, our results suggest that overexpression of GmST1 significantly improves Arabidopsis tolerance to both salt and drought stresses and the gene may be a potential candidate for genetic engineering of salt- and drought-tolerant crops. PMID:27148284

  17. Soybean Salt Tolerance 1 (GmST1) Reduces ROS Production, Enhances ABA Sensitivity, and Abiotic Stress Tolerance in Arabidopsis thaliana.

    PubMed

    Ren, Shuxin; Lyle, Chimera; Jiang, Guo-Liang; Penumala, Abhishek

    2016-01-01

    Abiotic stresses, including high soil salinity, significantly reduce crop production worldwide. Salt tolerance in plants is a complex trait and is regulated by multiple mechanisms. Understanding the mechanisms and dissecting the components on their regulatory pathways will provide new insights, leading to novel strategies for the improvement of salt tolerance in agricultural and economic crops of importance. Here we report that soybean salt tolerance 1, named GmST1, exhibited strong tolerance to salt stress in the Arabidopsis transgenic lines. The GmST1-overexpressed Arabidopsis also increased sensitivity to ABA and decreased production of reactive oxygen species under salt stress. In addition, GmST1 significantly improved drought tolerance in Arabidopsis transgenic lines. GmST1 belongs to a 3-prime part of Glyma.03g171600 gene in the current version of soybean genome sequence annotation. However, comparative reverse transcription-polymerase chain reaction analysis around Glyma.03g171600 genomic region confirmed that GmST1 might serve as an intact gene in soybean leaf tissues. Unlike Glyma.03g171600 which was not expressed in leaves, GmST1 was strongly induced by salt treatment in the leaf tissues. By promoter analysis, a TATA box was detected to be positioned close to GmST1 start codon and a putative ABRE and a DRE cis-acting elements were identified at about 1 kb upstream of GmST1 gene. The data also indicated that GmST1-transgenic lines survived under drought stress and showed a significantly lower water loss than non-transgenic lines. In summary, our results suggest that overexpression of GmST1 significantly improves Arabidopsis tolerance to both salt and drought stresses and the gene may be a potential candidate for genetic engineering of salt- and drought-tolerant crops. PMID:27148284

  18. RSK2-induced stress tolerance enhances cell survival signals mediated by inhibition of GSK3β activity

    SciTech Connect

    Lee, Cheol-Jung; Lee, Mee-Hyun; Lee, Ji-Young; Song, Ji Hong; Lee, Hye Suk; Cho, Yong-Yeon

    2013-10-11

    Highlights: •We demonstrated a novel function of RSK2 in stress tolerance. •RSK2 deficiency enhanced apoptosis by calcium stress. •RSK2-mediated GSK3β phosphorylation at serine 9 increased calcium-induced stress tolerance. •Calcium stress-induced apoptosis inhibited by adding back of RSK2 into RSK2{sup −/−} MEFs. -- Abstract: Our previous studies demonstrated that RSK2 plays a key role in cell proliferation and transformation induced by tumor promoters such as epidermal growth factor (EGF) in mouse and human skin cells. However, no direct evidence has been found regarding the relationship of RSK2 and cell survival. In this study, we found that RSK2 interacted and phosphorylated GSK3β at Ser9. Notably, GSK3β phosphorylation at Ser9 was suppressed in RSK2{sup −/−} MEFs compared with RSK2{sup +/+} MEFs by stimulation of EGF and calcium ionophore A23187, a cellular calcium stressor. In proliferation, we found that RSK2 deficiency suppressed cell proliferation compared with RSK2{sup +/+} MEFs. In contrast, GSK3β{sup −/−} MEFs induced the cell proliferation compared with GSK3β{sup +/+} MEFs. Importantly, RSK2{sup −/−} MEFs were induced severe cellular morphology change by A23187 and enhanced G1/G0 and sub-G1 accumulation of the cell cycle phase compared with RSK2{sup +/+} MEFs. The sub-G1 induction in RSK2{sup −/−} MEFs by A23187 was correlated with increase of cytochrome c release, caspase-3 cleavage and apoptotic DNA fragmentation compared with RSK2{sup +/+} MEFs. Notably, return back of RSK2 into RSK2{sup −/−} MEFs restored A23187-induced morphological change, and decreased apoptosis, apoptotic DNA fragmentation and caspase-3 induction compared with RSK2{sup −/−}/mock MEFs. Taken together, our results demonstrated that RSK2 plays an important role in stress-tolerance and cell survival, resulting in cell proliferation and cancer development.

  19. Fluoride-Tolerant Mutants of Aspergillus niger Show Enhanced Phosphate Solubilization Capacity

    PubMed Central

    Silva, Ubiana de Cássia; Mendes, Gilberto de Oliveira; Silva, Nina Morena R. M.; Duarte, Josiane Leal; Silva, Ivo Ribeiro; Tótola, Marcos Rogério; Costa, Maurício Dutra

    2014-01-01

    P-solubilizing microorganisms are a promising alternative for a sustainable use of P against a backdrop of depletion of high-grade rock phosphates (RPs). Nevertheless, toxic elements present in RPs, such as fluorine, can negatively affect microbial solubilization. Thus, this study aimed at selecting Aspergillus niger mutants efficient at P solubilization in the presence of fluoride (F−). The mutants were obtained by exposition of conidia to UV light followed by screening in a medium supplemented with Ca3(PO4)2 and F−. The mutant FS1-555 showed the highest solubilization in the presence of F−, releasing approximately 70% of the P contained in Ca3(PO4)2, a value 1.7 times higher than that obtained for the wild type (WT). The mutant FS1-331 showed improved ability of solubilizing fluorapatites, increasing the solubilization of Araxá, Catalão, and Patos RPs by 1.7, 1.6, and 2.5 times that of the WT, respectively. These mutants also grew better in the presence of F−, indicating that mutagenesis allowed the acquisition of F− tolerance. Higher production of oxalic acid by FS1-331 correlated with its improved capacity for RP solubilization. This mutant represents a significant improvement and possess a high potential for application in solubilization systems with fluoride-rich phosphate sources. PMID:25310310

  20. The evolutionary origin of CIPK16: A gene involved in enhanced salt tolerance.

    PubMed

    Amarasinghe, Shanika; Watson-Haigh, Nathan S; Gilliham, Matthew; Roy, Stuart; Baumann, Ute

    2016-07-01

    Calcineurin B-like protein interacting protein kinases (CIPKs) are key regulators of pre-transcriptional and post-translational responses to abiotic stress. Arabidopsis thaliana CIPK16 (AtCIPK16) was identified from a forward genetic screen as a gene that mediates lower shoot salt accumulation and improved salinity tolerance in Arabidopsis and transgenic barley. Here, we aimed to gain an understanding of the evolution of AtCIPK16, and orthologues of CIPK16 in other plant species including barley, by conducting a phylogenetic analysis of terrestrial plant species. The resulting protein sequence based phylogenetic trees revealed a single clade that included AtCIPK16 along with two segmentally duplicated CIPKs, AtCIPK5 and AtCIPK25. No monocots had proteins that fell into this clade; instead the most closely related monocot proteins formed a group basal to the entire CIPK16, 5 and 25 clade. We also found that AtCIPK16 contains a core Brassicales specific indel and a putative nuclear localisation signal, which are synapomorphic characters of CIPK16 genes. In addition, we present a model that proposes the evolution of CIPK16, 5 and 25 clade. PMID:27044608

  1. Enhanced levels of nicotianamine promote iron accumulation and tolerance to calcareous soil in soybean.

    PubMed

    Nozoye, Tomoko; Kim, Suyoen; Kakei, Yusuke; Takahashi, Michiko; Nakanishi, Hiromi; Nishizawa, Naoko K

    2014-01-01

    Iron (Fe) is an essential nutrient in both plants and humans. Fe deficiency on calcareous soil with low Fe availability is a major agricultural problem. Nicotianamine (NA) is one of the Fe chelator in plants, which is involved in metal translocation into seeds, and serves as an antihypertensive substance in humans. In this study, soybean plants overexpressing the barley NA synthase 1 (HvNAS1) gene driven by the constitutive CaMV 35S promoter were produced using Agrobacterium-mediated transformation. The transgenic soybean showed no growth defect and grew normally. The NA content of transgenic soybean seeds was up to four-fold greater than that of non-transgenic (NT) soybean seeds. The level of HvNAS1 expression was positively correlated with the amount of NA, and a high concentration of NA was maintained in the seeds in succeeding generations. The Fe concentration was approximately two-fold greater in transgenic soybean seeds than in NT soybean seeds. Furthermore, the transgenic soybeans showed tolerance to low Fe availability in calcareous soil. Our results suggested that increasing the NA content in soybean seeds by the overexpression of HvNAS1 offers potential benefits for both human health and agricultural productivity. PMID:25047240

  2. Juvenile hormone-activated phospholipase C pathway enhances transcriptional activation by the methoprene-tolerant protein

    PubMed Central

    Liu, Pengcheng; Peng, Hong-Juan; Zhu, Jinsong

    2015-01-01

    Juvenile hormone (JH) is a key regulator of a wide diversity of developmental and physiological events in insects. Although the intracellular JH receptor methoprene-tolerant protein (MET) functions in the nucleus as a transcriptional activator for specific JH-regulated genes, some JH responses are mediated by signaling pathways that are initiated by proteins associated with plasma membrane. It is unknown whether the JH-regulated gene expression depends on the membrane-mediated signal transduction. In Aedes aegypti mosquitoes, we found that JH activated the phospholipase C (PLC) pathway and quickly increased the levels of inositol 1,4,5-trisphosphate, diacylglycerol, and intracellular calcium, leading to activation and autophosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII). When abdomens from newly emerged mosquitoes were cultured in vitro, the JH-activated gene expression was repressed substantially if specific inhibitors of PLC or CaMKII were added to the medium together with JH. In newly emerged female mosquitoes, RNAi-mediated depletion of PLC or CaMKII considerably reduced the expression of JH-responsive genes, including the Krüppel homolog 1 gene (AaKr-h1) and the early trypsin gene (AaET). JH-induced loading of MET to the promoters of AaKr-h1 and AaET was weakened drastically when either PLC or CaMKII was inactivated in the cultured tissues. Therefore, the results suggest that the membrane-initiated signaling pathway modifies the DNA-binding activity of MET via phosphorylation and thus facilitates the genomic responses to JH. In summary, this study reveals an interplay of genomic and nongenomic signaling mechanisms of JH. PMID:25825754

  3. Juvenile hormone-activated phospholipase C pathway enhances transcriptional activation by the methoprene-tolerant protein.

    PubMed

    Liu, Pengcheng; Peng, Hong-Juan; Zhu, Jinsong

    2015-04-14

    Juvenile hormone (JH) is a key regulator of a wide diversity of developmental and physiological events in insects. Although the intracellular JH receptor methoprene-tolerant protein (MET) functions in the nucleus as a transcriptional activator for specific JH-regulated genes, some JH responses are mediated by signaling pathways that are initiated by proteins associated with plasma membrane. It is unknown whether the JH-regulated gene expression depends on the membrane-mediated signal transduction. In Aedes aegypti mosquitoes, we found that JH activated the phospholipase C (PLC) pathway and quickly increased the levels of inositol 1,4,5-trisphosphate, diacylglycerol, and intracellular calcium, leading to activation and autophosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII). When abdomens from newly emerged mosquitoes were cultured in vitro, the JH-activated gene expression was repressed substantially if specific inhibitors of PLC or CaMKII were added to the medium together with JH. In newly emerged female mosquitoes, RNAi-mediated depletion of PLC or CaMKII considerably reduced the expression of JH-responsive genes, including the Krüppel homolog 1 gene (AaKr-h1) and the early trypsin gene (AaET). JH-induced loading of MET to the promoters of AaKr-h1 and AaET was weakened drastically when either PLC or CaMKII was inactivated in the cultured tissues. Therefore, the results suggest that the membrane-initiated signaling pathway modifies the DNA-binding activity of MET via phosphorylation and thus facilitates the genomic responses to JH. In summary, this study reveals an interplay of genomic and nongenomic signaling mechanisms of JH. PMID:25825754

  4. Revised scheme for the mechanism of photoinhibition and its application to enhance the abiotic stress tolerance of the photosynthetic machinery.

    PubMed

    Nishiyama, Yoshitaka; Murata, Norio

    2014-11-01

    When photosynthetic organisms are exposed to abiotic stress, their photosynthetic activity is significantly depressed. In particular, photosystem II (PSII) in the photosynthetic machinery is readily inactivated under strong light and this phenomenon is referred to as photoinhibition of PSII. Other types of abiotic stress act synergistically with light stress to accelerate photoinhibition. Recent studies of photoinhibition have revealed that light stress damages PSII directly, whereas other abiotic stresses act exclusively to inhibit the repair of PSII after light-induced damage (photodamage). Such inhibition of repair is associated with suppression, by reactive oxygen species (ROS), of the synthesis of proteins de novo and, in particular, of the D1 protein, and also with the reduced efficiency of repair under stress conditions. Gene-technological improvements in the tolerance of photosynthetic organisms to various abiotic stresses have been achieved via protection of the repair system from ROS and, also, by enhancing the efficiency of repair via facilitation of the turnover of the D1 protein in PSII. In this review, we summarize the current status of research on photoinhibition as it relates to the effects of abiotic stress and we discuss successful strategies that enhance the activity of the repair machinery. In addition, we propose several potential methods for activating the repair system by gene-technological methods. PMID:25139449

  5. Independent evolution of four heme peroxidase superfamilies.

    PubMed

    Zámocký, Marcel; Hofbauer, Stefan; Schaffner, Irene; Gasselhuber, Bernhard; Nicolussi, Andrea; Soudi, Monika; Pirker, Katharina F; Furtmüller, Paul G; Obinger, Christian

    2015-05-15

    Four heme peroxidase superfamilies (peroxidase-catalase, peroxidase-cyclooxygenase, peroxidase-chlorite dismutase and peroxidase-peroxygenase superfamily) arose independently during evolution, which differ in overall fold, active site architecture and enzymatic activities. The redox cofactor is heme b or posttranslationally modified heme that is ligated by either histidine or cysteine. Heme peroxidases are found in all kingdoms of life and typically catalyze the one- and two-electron oxidation of a myriad of organic and inorganic substrates. In addition to this peroxidatic activity distinct (sub)families show pronounced catalase, cyclooxygenase, chlorite dismutase or peroxygenase activities. Here we describe the phylogeny of these four superfamilies and present the most important sequence signatures and active site architectures. The classification of families is described as well as important turning points in evolution. We show that at least three heme peroxidase superfamilies have ancient prokaryotic roots with several alternative ways of divergent evolution. In later evolutionary steps, they almost always produced highly evolved and specialized clades of peroxidases in eukaryotic kingdoms with a significant portion of such genes involved in coding various fusion proteins with novel physiological functions. PMID:25575902

  6. (Characterization of lignin peroxidases from Phanerochaete)

    SciTech Connect

    Not Available

    1990-11-14

    Work has continued on characterizing the kinetics of lignin peroxidases and has now expanded to include the chemistry of Mn peroxidases. Progress in these two area in addition to the authors work on the molecular biology of lignin biodegradation is briefly described below. Copies of two reprints and one preprint which have resulted from the work are attached.

  7. Peroxidase catalyzed polymerization of phenol

    SciTech Connect

    Vasudevan, P.T.; Li, L.O.

    1996-07-01

    The effect of horseradish peroxidase (HRP) and H{sub 2}O{sub 2} concentrations on the removal efficiency of phenol, defined as the percentage of phenol removed from solution as a function of time, has been investigated. When phenol and H{sub 2}O{sub 2} react with an approximately one-to-one stoichiometry, the phenol is almost completely precipitated within 10 min. The reaction is inhibited at higher concentrations of H{sub 2}O{sub 2}. The removal efficiency increases with an increase in the concentration of HRP, but an increase in the time of treatment cannot be used to offset the reduction in removal efficiency at low concentrations of the enzyme, because of inactivation of the enzyme. One molecule of HRP is needed to remove approximately 1100 molecules of phenol when the reaction is conducted at pH 8.0 and at ambient temperature. 9 refs., 5 figs.

  8. Tetraploidy Enhances Boron-Excess Tolerance in Carrizo Citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.)

    PubMed Central

    Ruiz, Marta; Quiñones, Ana; Martínez-Alcántara, Belén; Aleza, Pablo; Morillon, Raphaël; Navarro, Luis; Primo-Millo, Eduardo; Martínez-Cuenca, Mary-Rus

    2016-01-01

    Tetraploidy modifies root anatomy which may lead to differentiated capacity to uptake and transport mineral elements. This work provides insights into physiological and molecular characters involved in boron (B) toxicity responses in diploid (2x) and tetraploid (4x) plants of Carrizo citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.), a widely used citrus rootstock. With B excess, 2x plants accumulated more B in leaves than 4x plants, which accounted for their higher B uptake and root-to-shoot transport rates. Ploidy did not modify the expression of membrane transporters NIP5 and BOR1 in roots. The cellular allocation of B excess differed between ploidy levels in the soluble fraction, which was lower in 4x leaves, while cell wall-linked B was similar in 2x and 4x genotypes. This correlates with the increased damage and stunted growth recorded in the 2x plants. The 4x roots were found to have fewer root tips, shorter specific root length, longer diameter, thicker exodermis and earlier tissue maturation in root tips, where the Casparian strip was detected at a shorter distance from the root apex than in the 2x roots. The results presented herein suggest that the root anatomical characters of the 4x plants play a key role in their lower B uptake capacity and root-to-shoot transport. Highlights Tetraploidy enhances B excess tolerance in citrange Carrizo Expression of NIP5 and BOR1 transporters and cell wall-bounded B are similar between ploidies B tolerance is attributed to root anatomical modifications induced by genome duplication The rootstock 4x citrange carrizo may prevent citrus trees from B excess. PMID:27252717

  9. SNP marker discovery, linkage map construction and identification of QTLs for enhanced salinity tolerance in field pea (Pisum sativum L.)

    PubMed Central

    2013-01-01

    selection of resistant cultivars. Comparison of sequences underpinning these SNP markers to the M. truncatula genome defined genomic regions containing candidate genes associated with saline stress tolerance. Conclusion The SNP assays and associated genetic linkage maps developed in this study permitted identification of salinity tolerance QTLs and candidate genes. This constitutes an important set of tools for marker-assisted selection (MAS) programs aimed at performance enhancement of field pea cultivars. PMID:24134188

  10. Chlorophyll enhances oxidative stress tolerance in Caenorhabditis elegans and extends its lifespan

    PubMed Central

    Wang, Erjia

    2016-01-01

    Green vegetables are thought to be responsible for several beneficial properties such as antioxidant, anti-mutagenic, and detoxification activities. It is not known whether these effects are due to chlorophyll which exists in large amounts in many foods or result from other secondary metabolites. In this study, we used the model system Caenorhabditis elegans to investigate the anti-oxidative and anti-aging effects of chlorophyll in vivo. We found that chlorophyll significantly improves resistance to oxidative stress. It also enhances the lifespan of C. elegans by up to 25% via activation of the DAF-16/FOXO-dependent pathway. The results indicate that chlorophyll is absorbed by the worms and is thus bioavailable, constituting an important prerequisite for antioxidant and longevity-promoting activities inside the body. Our study thereby supports the view that green vegetables may also be beneficial for humans. PMID:27077003

  11. Expression of Multiple Resistance Genes Enhances Tolerance to Environmental Stressors in Transgenic Poplar (Populus × euramericana ‘Guariento’)

    PubMed Central

    Su, Xiaohua; Chu, Yanguang; Li, Huan; Hou, Yingjie; Zhang, Bingyu; Huang, Qinjun; Hu, Zanmin; Huang, Rongfeng; Tian, Yingchuan

    2011-01-01

    Commercial and non-commercial plants face a variety of environmental stressors that often cannot be controlled. In this study, transgenic hybrid poplar (Populus × euramericana ‘Guariento’) harboring five effector genes (vgb, SacB, JERF36, BtCry3A and OC-I) were subjected to drought, salinity, waterlogging and insect stressors in greenhouse or laboratory conditions. Field trials were also conducted to investigate long-term effects of transgenic trees on insects and salt tolerance in the transformants. In greenhouse studies, two transgenic lines D5-20 and D5-21 showed improved growth, as evidenced by greater height and basal diameter increments and total biomass relative to the control plants after drought or salt stress treatments. The improved tolerance to drought and salt was primarily attributed to greater instantaneous water use efficiency (WUEi) in the transgenic trees. The chlorophyll concentrations tended to be higher in the transgenic lines under drought or saline conditions. Transformed trees in drought conditions accumulated more fructan and proline and had increased Fv/Fm ratios (maximum quantum yield of photosystem II) under waterlogging stress. Insect-feeding assays in the laboratory revealed a higher total mortality rate and lower exuviation index of leaf beetle [Plagiodera versicolora (Laicharting)] larvae fed with D5-21 leaves, suggesting enhanced insect resistance in the transgenic poplar. In field trials, the dominance of targeted insects on 2-year-old D5-21 transgenic trees was substantially lower than that of the controls, indicating enhanced resistance to Coleoptera. The average height and DBH (diameter at breast height) of 2.5-year-old transgenic trees growing in naturally saline soil were 3.80% and 4.12% greater than those of the control trees, but these increases were not significant. These results suggested that multiple stress-resistance properties in important crop tree species could be simultaneously improved, although additional

  12. Sfp-type PPTase inactivation promotes bacterial biofilm formation and ability to enhance wheat drought tolerance.

    PubMed

    Timmusk, Salme; Kim, Seong-Bin; Nevo, Eviatar; Abd El Daim, Islam; Ek, Bo; Bergquist, Jonas; Behers, Lawrence

    2015-01-01

    Paenibacillus polymyxa is a common soil bacterium with broad range of practical applications. An important group of secondary metabolites in P. polymyxa are non-ribosomal peptide and polyketide derived metabolites (NRPs/PKs). Modular non-ribosomal peptide synthetases catalyze main steps in the biosynthesis of the complex secondary metabolites. Here we report on the inactivation of an A26 Sfp-type 4'-phosphopantetheinyl transferase (Sfp-type PPTase). The inactivation of the gene resulted in loss of NRPs/PKs production. In contrast to the former Bacillus spp. model the mutant strain compared to wild type showed greatly enhanced biofilm formation ability. A26Δsfp biofilm promotion is directly mediated by NRPs/PKs, as exogenous addition of the wild type metabolite extracts restores its biofilm formation level. Wheat inoculation with bacteria that had lost their Sfp-type PPTase gene resulted in two times higher plant survival and about three times increased biomass under severe drought stress compared to wild type. Challenges with P. polymyxa genetic manipulation are discussed. PMID:26052312

  13. Sfp-type PPTase inactivation promotes bacterial biofilm formation and ability to enhance wheat drought tolerance

    PubMed Central

    Timmusk, Salme; Kim, Seong-Bin; Nevo, Eviatar; Abd El Daim, Islam; Ek, Bo; Bergquist, Jonas; Behers, Lawrence

    2015-01-01

    Paenibacillus polymyxa is a common soil bacterium with broad range of practical applications. An important group of secondary metabolites in P. polymyxa are non-ribosomal peptide and polyketide derived metabolites (NRPs/PKs). Modular non-ribosomal peptide synthetases catalyze main steps in the biosynthesis of the complex secondary metabolites. Here we report on the inactivation of an A26 Sfp-type 4'-phosphopantetheinyl transferase (Sfp-type PPTase). The inactivation of the gene resulted in loss of NRPs/PKs production. In contrast to the former Bacillus spp. model the mutant strain compared to wild type showed greatly enhanced biofilm formation ability. A26Δsfp biofilm promotion is directly mediated by NRPs/PKs, as exogenous addition of the wild type metabolite extracts restores its biofilm formation level. Wheat inoculation with bacteria that had lost their Sfp-type PPTase gene resulted in two times higher plant survival and about three times increased biomass under severe drought stress compared to wild type. Challenges with P. polymyxa genetic manipulation are discussed. PMID:26052312

  14. Productivity of sodic soils can be enhanced through the use of salt tolerant rice varieties and proper agronomic practices

    PubMed Central

    Singh, Y.P.; Mishra, V.K.; Singh, Sudhanshu; Sharma, D.K.; Singh, D.; Singh, U.S.; Singh, R.K.; Haefele, S.M.; Ismail, A.M.

    2016-01-01

    Regaining the agricultural potential of sodic soils in the Indo-Gangetic plains necessitates the development of suitable salt tolerant rice varieties to provide an entry for other affordable agronomic and soil manipulation measures. Thus selection of high yielding rice varieties across a range of sodic soils is central. Evaluation of breeding lines through on-station and on-farm farmers’ participatory varietal selection (FPVS) resulted in the identification of a short duration (110–115 days), high yielding and disease resistant salt-tolerant rice genotype ‘CSR-89IR-8’, which was later released as ‘CSR43’ in 2011. Several agronomic traits coupled with good grain quality and market value contributed to commercialization and quick adoption of this variety in the sodic areas of the Indo-Gangetic plains of eastern India. Management practices required for rice production in salt affected soils are evidently different from those in normal soils and practices for a short duration salt tolerant variety differ from those for medium to long duration varieties. Experiments were conducted at the Indian Council of Agricultural Research-Central Soil Salinity Research Institute (ICAR-CSSRI), Regional Research Station, Lucknow, Uttar Pradesh, India during 2011 and 2013 wet seasons, to test the hypothesis that combining matching management practices (Mmp) with an improved genotype would enhance productivity and profitability of rice in sodic soils. Mmp were developed on-station by optimizing existing best management practices (Bmp) recommended for the region to match the requirements of CSR43. The results revealed that transplanting 4 seedlings hill−1 at a spacing of 15 × 20 cm produced significantly higher yield over other treatments. The highest additional net gain was US$ 3.3 at 90 kg ha−1 N, and the lowest was US$ 0.4 at 150 kg ha−1 N. Above 150 kg ha−1, the additional net gain became negative, indicating decreasing returns from additional N

  15. Preliminary Results on FeCrAl Alloys in the As-received and Welded State Designed to Have Enhanced Weldability and Radiation Tolerance

    SciTech Connect

    Field, Kevin G.; Gussev, Maxim N.; Hu, Xunxiang; Yamamoto, Yukinori

    2015-09-30

    The present report summarizes and discusses the recent results on developing a modern, nuclear grade FeCrAl alloy designed to have enhanced radiation tolerance and weldability. The alloys used for these investigations are modern FeCrAl alloys based on a Fe-13Cr-5Al-2Mo-0.2Si-0.05Y alloy (in wt.%, designated C35M). Development efforts have focused on assessing the influence of chemistry and microstructure on the fabricability and performance of these newly developed alloys. Specific focus was made to assess the weldability, thermal stability, and radiation tolerance.

  16. Selenium, glutathione peroxidase and other selenoproteins

    SciTech Connect

    Wilhelmsen, E.C.

    1983-01-01

    Selenium, as essential trace element, has long been associated with protein. The essentiality of selenium is partially understood as glutathione peroxidase contains an essential selenocysteine. Glutathione peroxidase has been purified from many tissues including rat liver. An estimated molecular weight of 105,000 was obtained for glutathione peroxidase by comparison to standards. A subunit size of 26,000 was obtained by SDS-gel electrophoresis. Glutathione peroxidase is not the only selenoprotein in the rat. In seven rat tissues examined, there were many different subunit sizes and change groups representing between 9 and 23 selenoproteins. Selenocysteine in glutathione peroxidase accounts for ca. 36% of the selenium in the rat. The mode of synthesis of glutathione peroxidase and the other selenoproteins is not understood. Glutathione peroxidase is strongly and reversibly inhibited by mercaptocarboxylic acids and other mercaptans, including some used as slow-acting drugs for the symtomatic treatment of rheumatoid arthritis. The mechanism and chemistry of this inhibition is discussed. This inhibition may provide a link between selenium and arthritis.

  17. Antisense RNA suppression of peroxidase gene expression

    SciTech Connect

    Lagrimini, L.M.; Bradford, S.; De Leon, F.D. )

    1989-04-01

    The 5{prime} half the anionic peroxidase cDNA of tobacco was inserted into a CaMV 35S promoter/terminator expression cassette in the antisense configuration. This was inserted into the Agrobacterium-mediated plant transformation vector pCIBIO which includes kanamycin selection, transformed into two species of tobacco (N. tabacum and M. sylvestris), and plants were subsequently regenerated on kanamycin. Transgenic plants were analyzed for peroxidase expression and found to have 3-5 fold lower levels of peroxidase than wild-type plants. Isoelectric focusing demonstrated that the antisense RNA only suppressed the anionic peroxidase. Wound-induced peroxidase expression was found not to be affected by the antisense RNA. Northern blots show a greater than 5 fold suppression of anionic peroxidase mRNA in leaf tissue, and the antisense RNA was expressed at a level 2 fold over the endogenous mRNA. Plants were self-pollinated and F1 plants showed normal segregation. N. sylvestris transgenic plants with the lowest level of peroxidase are epinastic, and preliminary results indicate elevated auxin levels. Excised pith tissue from both species of transgenic plants rapidly collapse when exposed to air, while pith tissue from wild-type plants showed little change when exposed to air. Further characterization of these phenotypes is currently being made.

  18. Soybean peroxidase as an industrial catalyst

    SciTech Connect

    Pokora, A.R.

    1995-12-01

    Peroxidases are a large class of enzymes which are very efficient at catalysing oxidation reactions. Horseradish peroxidase, the most abundant and commercially available peroxidase, has been utilized for many years in medical diagnostic test kits but has never been used successfully in an industrial application. One of the major drawbacks associated with the peroxidases cost and has been their lack of the thermal stability required in an industrial process. Recently, we isolated has been their lack of the peroxidase from soybean seed coats. Soybean seed coats are a commodity product available year round in very large volumes. The useful operational temperature for the soy peroxidase is 40{degrees}C higher than for horseradish peroxidase resulting in shorter reaction times and greater reactor efficiency. This process can be used to produce formaldehyde-free polyphenols as well as numerous phenolic dimers used in the manufacture of anti-oxidants, U-V absorbers, epoxies as well as other materials. The process to manufacture resins and dimers will be discussed.

  19. Recents patents in the use of peroxidases.

    PubMed

    Alvarado, Berenize; Torres, Eduardo

    2009-01-01

    Peroxidases are hemoenzymes with a wide range of applications, from fine chemical synthesis to environmental biocatalysis. These outstanding biocatalysts are able to catalyze reactions such as heteroatom oxidation (N- and S-oxidation), epoxidation, hydroxylation, and the oxidation of alcohols and indole, often giving high yields and enantiomeric excess values. This makes these biocatalysts very useful for application to several biotechnological processes. In this paper, recent advances and patents surrounding the use of peroxidases are reviewed, covering different aspects related to the applications of peroxidases and the modifications carried out to improve their functionality as biocatalysts. PMID:19519565

  20. A putative soybean GmsSOS1 confers enhanced salt tolerance to transgenic Arabidopsis sos1-1 mutant.

    PubMed

    Nie, Wang-Xing; Xu, Lin; Yu, Bing-Jun

    2015-01-01

    The cDNA of GmsSOS1, a putative plasma membrane Na(+)/H(+) antiporter gene isolated from Glycine max, Glycine soja, and their hybrid, was constructed into plant expression vector pCAMBIA 1300 and then transformed with Agrobacterium tumefaciens under the control of CaMV 35S promoter to Arabidopsis thaliana wild-type (WT) and mutant (atsos1-1) plants. By hygromycin resistance detection and PCR analysis, transgenic plants (WT35S:GmsSOS1 and atsos1-1 35S:GmsSOS1) were obtained. Seed germination, seedling growth, and Na(+) contents in roots and shoots were analytically compared among WT, atsos1-1 mutant, and their transgenic lines under salt stress. The results showed that when GmsSOS1 was integrated into the genome of A. thaliana, the inhibitions of salt stress on seed germination and seedling growth were all significantly improved, and enhanced salt tolerance was displayed, which may be attributed to the decrease of Na(+) absorption in roots and transportation in shoots of the transgenic lines, especially for that of atsos1-1 mutant. PMID:24934653

  1. CmWRKY1 Enhances the Dehydration Tolerance of Chrysanthemum through the Regulation of ABA-Associated Genes.

    PubMed

    Fan, Qingqing; Song, Aiping; Jiang, Jiafu; Zhang, Ting; Sun, Hainan; Wang, Yinjie; Chen, Sumei; Chen, Fadi

    2016-01-01

    WRKY transcription factors serve as antagonistic or synergistic regulators in a variety of abiotic stress responses in plants. Here, we show that CmWRKY1, a member of the group IIb WRKY family isolated from Chrysanthemum morifolium, exhibits no transcriptional activation in yeast cells. The subcellular localization examination showed that CmWRKY1 localizes to the nucleus in vivo. Furthermore, CmWRKY1-overexpressing transgenic lines exhibit enhanced dehydration tolerance in response to polyethylene glycol (PEG) treatment compared with wild-type plants. We further confirmed that the transgenic plants exhibit suppressed expression levels of genes negatively regulated by ABA, such as PP2C, ABI1 and ABI2, and activated expression levels of genes positively regulated by ABA, such as PYL2, SnRK2.2, ABF4, MYB2, RAB18, and DREB1A. Taken together, our results indicate that CmWRKY1 plays an important role in the response to drought in chrysanthemum through an ABA-mediated pathway. PMID:26938878

  2. The Novel Wheat Transcription Factor TaNAC47 Enhances Multiple Abiotic Stress Tolerances in Transgenic Plants

    PubMed Central

    Zhang, Lina; Zhang, Lichao; Xia, Chuan; Zhao, Guangyao; Jia, Jizeng; Kong, Xiuying

    2016-01-01

    NAC transcription factors play diverse roles in plant development and responses to abiotic stresses. However, the biological roles of NAC family members in wheat are not well understood. Here, we reported the isolation and functional characterization of a novel wheat TaNAC47 gene. TaNAC47 encoded protein, localizing in the nucleus, is able to bind to the ABRE cis-element and transactivate transcription in yeast, suggesting that it likely functions as a transcriptional activator. We also showed that TaNAC47 is differentially expressed in different tissues, and its expression was induced by the stress treatments of salt, cold, polyethylene glycol and exogenous abscisic acid. Furthermore, overexpression of TaNAC47 in Arabidopsis resulted in ABA hypersensitivity and enhancing tolerance of transgenic plants to drought, salt, and freezing stresses. Strikingly, overexpression of TaNAC47 was found to activate the expression of downstream genes and change several physiological indices that may enable transgenic plants to overcome unfavorable environments. Taken together, these results uncovered an important role of wheat TaNAC47 gene in response to ABA and abiotic stresses. PMID:26834757

  3. CmWRKY1 Enhances the Dehydration Tolerance of Chrysanthemum through the Regulation of ABA-Associated Genes

    PubMed Central

    Fan, Qingqing; Song, Aiping; Jiang, Jiafu; Zhang, Ting; Sun, Hainan; Wang, Yinjie; Chen, Sumei; Chen, Fadi

    2016-01-01

    WRKY transcription factors serve as antagonistic or synergistic regulators in a variety of abiotic stress responses in plants. Here, we show that CmWRKY1, a member of the group IIb WRKY family isolated from Chrysanthemum morifolium, exhibits no transcriptional activation in yeast cells. The subcellular localization examination showed that CmWRKY1 localizes to the nucleus in vivo. Furthermore, CmWRKY1-overexpressing transgenic lines exhibit enhanced dehydration tolerance in response to polyethylene glycol (PEG) treatment compared with wild-type plants. We further confirmed that the transgenic plants exhibit suppressed expression levels of genes negatively regulated by ABA, such as PP2C, ABI1 and ABI2, and activated expression levels of genes positively regulated by ABA, such as PYL2, SnRK2.2, ABF4, MYB2, RAB18, and DREB1A. Taken together, our results indicate that CmWRKY1 plays an important role in the response to drought in chrysanthemum through an ABA-mediated pathway. PMID:26938878

  4. In-plane current-driven spin-orbit torque switching in perpendicularly magnetized films with enhanced thermal tolerance

    NASA Astrophysics Data System (ADS)

    Wu, Di; Yu, Guoqiang; Shao, Qiming; Li, Xiang; Wu, Hao; Wong, Kin L.; Zhang, Zongzhi; Han, Xiufeng; Khalili Amiri, Pedram; Wang, Kang L.

    2016-05-01

    We study spin-orbit-torque (SOT)-driven magnetization switching in perpendicularly magnetized Ta/Mo/Co40Fe40B20 (CoFeB)/MgO films. The thermal tolerance of the perpendicular magnetic anisotropy (PMA) is enhanced, and the films sustain the PMA at annealing temperatures of up to 430 °C, due to the ultra-thin Mo layer inserted between the Ta and CoFeB layers. More importantly, the Mo insertion layer also allows for the transmission of the spin current generated in the Ta layer due to spin Hall effect, which generates a damping-like SOT and is able to switch the perpendicular magnetization. When the Ta layer is replaced by a Pt layer, i.e., in a Pt/Mo/CoFeB/MgO multilayer, the direction of the SOT-induced damping-like effective field becomes opposite because of the opposite sign of spin Hall angle in Pt, which indicates that the SOT-driven switching is dominated by the spin current generated in the Ta or Pt layer rather than the Mo layer. Quantitative characterization through harmonic measurements reveals that the large SOT effective field is preserved for high annealing temperatures. This work provides a route to applying SOT in devices requiring high temperature processing steps during the back-end-of-line processes.

  5. The Expression of Millettia pinnata Chalcone Isomerase in Saccharomyces cerevisiae Salt-Sensitive Mutants Enhances Salt-Tolerance

    PubMed Central

    Wang, Hui; Hu, Tangjin; Huang, Jianzi; Lu, Xiang; Huang, Baiqu; Zheng, Yizhi

    2013-01-01

    The present study demonstrates a new Millettia pinnata chalcone isomerase (MpCHI) whose transcription level in leaf was confirmed to be enhanced after being treated by seawater or NaCl (500 mM) via transcriptome sequencing and Real-Time Quantitative Reverse Transcription PCR (QRT-PCR) analyses. Its full length cDNA (666 bp) was obtained by 3′-end and 5′-end Rapid Amplification of cDNA Ends (RACE). The analysis via NCBI BLAST indicates that both aminoacid sequence and nucleotide sequence of the MpCHI clone share high homology with other leguminous CHIs (73%–86%). Evolutionarily, the phylogenic analysis further revealed that the MpCHI is a close relative of leguminous CHIs. The MpCHI protein consists of 221 aminoacid (23.64 KDa), whose peptide length, amino acid residues of substrate-binding site and reactive site are very similar to other leguminous CHIs reported previously. Two pYES2-MpCHI transformed salt-sensitive Saccharomyces cerevisiae mutants (Δnha1 and Δnhx1) showed improved salt-tolerance significantly compared to pYES2-vector transformed yeast mutants, suggesting the MpCHI or the flavonoid biosynthesis pathway could regulate the resistance to salt stress in M. pinnata. PMID:23615469

  6. Phytotoxin coronatine enhances heat tolerance via maintaining photosynthetic performance in wheat based on Electrophoresis and TOF-MS analysis

    PubMed Central

    Zhou, Yuyi; Zhang, Mingcai; Li, Jianmin; Li, Zhaohu; Tian, Xiaoli; Duan, Liusheng

    2015-01-01

    Coronatine (COR) is a phytotoxin produced by Pseudomonas syringae. Its structure is similar to Jasmonates, which play a number of diverse roles in plant defense. Both have the COI1 plant receptor, so coronatine can manipulate plant hormone signaling to access nutrients and counteract defense responses. In addition to the hormone system, coronatine affects plant nitrogenous metabolism and chloroplast ultrastructure. In this study, we first examined a typical nitrogen-losing phenotype, and used the polyacrylamide gel approach to demonstrate soluble total protein patterns in a time-course experiment under different temperature conditions. We then employed dimensional gel electrophoresis technology (2-DE) and MALDI-TOF-MS to sequester and identify the sensitive proteins. We found a total of 27 coronatine sensitive proteins, 22 of which were located in the chloroplast and 6 of which were directly involved in photosynthesis. Finally, we measured levels of chlorophyll and photosynthetic performance to reveal the phenotypic effect of these proteins. Taken together, these results demonstrated that coronatine enhanced heat tolerance by regulating nitrogenous metabolism and chloroplast ultrastructure to maintain photosynthetic performance and reduce yield loss under heat stress. PMID:26347991

  7. Verticillium infection triggers VASCULAR-RELATED NAC DOMAIN7-dependent de novo xylem formation and enhances drought tolerance in Arabidopsis.

    PubMed

    Reusche, Michael; Thole, Karin; Janz, Dennis; Truskina, Jekaterina; Rindfleisch, Sören; Drübert, Christine; Polle, Andrea; Lipka, Volker; Teichmann, Thomas

    2012-09-01

    The soilborne fungal plant pathogen Verticillium longisporum invades the roots of its Brassicaceae hosts and proliferates in the plant vascular system. Typical aboveground symptoms of Verticillium infection on Brassica napus and Arabidopsis thaliana are stunted growth, vein clearing, and leaf chloroses. Here, we provide evidence that vein clearing is caused by pathogen-induced transdifferentiation of chloroplast-containing bundle sheath cells to functional xylem elements. In addition, our findings suggest that reinitiation of cambial activity and transdifferentiation of xylem parenchyma cells results in xylem hyperplasia within the vasculature of Arabidopsis leaves, hypocotyls, and roots. The observed de novo xylem formation correlates with Verticillium-induced expression of the VASCULAR-RELATED NAC DOMAIN (VND) transcription factor gene VND7. Transgenic Arabidopsis plants expressing the chimeric repressor VND7-SRDX under control of a Verticillium infection-responsive promoter exhibit reduced de novo xylem formation. Interestingly, infected Arabidopsis wild-type plants show higher drought stress tolerance compared with noninfected plants, whereas this effect is attenuated by suppression of VND7 activity. Together, our results suggest that V. longisporum triggers a tissue-specific developmental plant program that compensates for compromised water transport and enhances the water storage capacity of infected Brassicaceae host plants. In conclusion, we provide evidence that this natural plant-fungus pathosystem has conditionally mutualistic features. PMID:23023171

  8. Combined effects of cadmium and zinc on growth, tolerance, and metal accumulation in Chara australis and enhanced phytoextraction using EDTA.

    PubMed

    Clabeaux, Bernadette L; Navarro, Divina A; Aga, Diana S; Bisson, Mary A

    2013-12-01

    Chara australis (R. Br.) is a macrophytic alga that can grow in and accumulate Cd from artificially contaminated sediments. We investigated the effects of Zn independently and in combination with Cd on C. australis growth, metal tolerance, and uptake. Plant growth was reduced at concentrations ≥ 75 mg Zn (kg soil)⁻¹. Zn also increased the concentration of glutathione in the plant, suggesting alleviation of stress. Phytotoxic effects were observed at ≥ 250 mg added Zn (kg soil)⁻¹. At 1.5mg Zn (kg soil)⁻¹, the rhizoid bioconcentration factor (BCF) was >1.0 for both Cd and Zn. This is a criterion for hyperaccumulator status, a commonly used benchmark for utility in remediation of contaminated soils by phytoextraction. There was no significant interaction between Cd and Zn on accumulation, indicating that Chara should be effective at phytoextraction of mixed heavy metal contamination in sediments. The effects of the chelator, ethylenediaminetetraacetic acid (EDTA), were also tested. Moderate levels of EDTA increased Cd and Zn accumulation in rhizoids and Cd BCF of shoots, enhancing Chara's potential in phytoremediation. This study demonstrates for the first time the potential of macroalgae to remove metals from sediments in aquatic systems that are contaminated with a mixture of metals. PMID:24035462

  9. Enhanced tolerance and accumulation of heavy metal ions by engineered Escherichia coli expressing Pyrus calleryana phytochelatin synthase.

    PubMed

    Li, Hui; Cong, Yu; Lin, Jing; Chang, Youhong

    2015-03-01

    Contamination by heavy metals is a major environmental problem worldwide and microbial bioremediation is an efficient method for removing this type of pollution. The plant enzymephytochelatin synthase (PCS, also known as glutathione g-glutamylcysteinyltransferase, EC2.3.2.15) involved in the synthesis of phytochelatins (PCs), which are metal-binding cysteine-rich peptides, has a major role in the detoxification of heavy metals in plants. Expression of the PcPCS1 gene from the bean pear (Pyrus calleryana Dcne.) was induced after cadmium and copper treatments. However, functional analysis of this gene in vivo has not been reported. And it is or not suitable for bioremediation also needs to be assessed. In this study, we found Escherichia coli with over-expressed PcPCS1 had enhanced tolerance to cadmium, copper, sodium, and mercury. E. colicells transformed with pPcPCS1 was found to survive in solid M9 medium containing 2.0 mM Cd(2+), 4.0 mM Cu(2+). 4.5% (w/v) Na+, or 200 μ MHg(2+). Moreover, the growth curve showed 1.5 mM Cd(2+), 2.5 mM Cu(2+), 3.5% (w/v) Naþ, and 100 μ MHg(2+) had no effect on the growth of the E. coli cells transformed with pPcPCS1. Also, we found the contents of PCs and the accumulation of cadmium,copper, sodium, and mercury ions were enhanced in the recombinant E. coli strain Rosetta(TM) (DE3).These results suggested the PcPCS1 gene might be a candidate for heavy metal bioremediation via recombinant bacteria. PMID:25727053

  10. Redundancy among manganese peroxidases in Pleurotus ostreatus.

    PubMed

    Salame, Tomer M; Knop, Doriv; Levinson, Dana; Yarden, Oded; Hadar, Yitzhak

    2013-04-01

    Manganese peroxidases (MnPs) are key players in the ligninolytic system of white rot fungi. In Pleurotus ostreatus (the oyster mushroom) these enzymes are encoded by a gene family comprising nine members, mnp1 to -9 (mnp genes). Mn(2+) amendment to P. ostreatus cultures results in enhanced degradation of recalcitrant compounds (such as the azo dye orange II) and lignin. In Mn(2+)-amended glucose-peptone medium, mnp3, mnp4, and mnp9 were the most highly expressed mnp genes. After 7 days of incubation, the time point at which the greatest capacity for orange II decolorization was observed, mnp3 expression and the presence of MnP3 in the extracellular culture fluids were predominant. To determine the significance of MnP3 for ligninolytic functionality in Mn(2+)-sufficient cultures, mnp3 was inactivated via the Δku80 strain-based P. ostreatus gene-targeting system. In Mn(2+)-sufficient medium, inactivation of mnp3 did not significantly affect expression of nontargeted MnPs or their genes, nor did it considerably diminish the fungal Mn(2+)-mediated orange II decolorization capacity, despite the significant reduction in total MnP activity. Similarly, inactivation of either mnp4 or mnp9 did not affect orange II decolorization ability. These results indicate functional redundancy within the P. ostreatus MnP gene family, enabling compensation upon deficiency of one of its members. PMID:23377936

  11. Redundancy among Manganese Peroxidases in Pleurotus ostreatus

    PubMed Central

    Salame, Tomer M.; Knop, Doriv; Levinson, Dana; Yarden, Oded

    2013-01-01

    Manganese peroxidases (MnPs) are key players in the ligninolytic system of white rot fungi. In Pleurotus ostreatus (the oyster mushroom) these enzymes are encoded by a gene family comprising nine members, mnp1 to -9 (mnp genes). Mn2+ amendment to P. ostreatus cultures results in enhanced degradation of recalcitrant compounds (such as the azo dye orange II) and lignin. In Mn2+-amended glucose-peptone medium, mnp3, mnp4, and mnp9 were the most highly expressed mnp genes. After 7 days of incubation, the time point at which the greatest capacity for orange II decolorization was observed, mnp3 expression and the presence of MnP3 in the extracellular culture fluids were predominant. To determine the significance of MnP3 for ligninolytic functionality in Mn2+-sufficient cultures, mnp3 was inactivated via the Δku80 strain-based P. ostreatus gene-targeting system. In Mn2+-sufficient medium, inactivation of mnp3 did not significantly affect expression of nontargeted MnPs or their genes, nor did it considerably diminish the fungal Mn2+-mediated orange II decolorization capacity, despite the significant reduction in total MnP activity. Similarly, inactivation of either mnp4 or mnp9 did not affect orange II decolorization ability. These results indicate functional redundancy within the P. ostreatus MnP gene family, enabling compensation upon deficiency of one of its members. PMID:23377936

  12. Inhibition of Peroxidase Activity of Cytochrome c: De Novo Compound Discovery and Validation

    PubMed Central

    Bakan, Ahmet; Kapralov, Alexandr A.; Bayir, Hulya; Hu, Feizhou; Kagan, Valerian E.

    2015-01-01

    Cytochrome c (cyt c) release from mitochondria is accepted to be the point of no return for eliciting a cascade of interactions that lead to apoptosis. A strategy for containing sustained apoptosis is to reduce the mitochondrial permeability pore opening. Pore opening is enhanced by peroxidase activity of cyt c gained upon its complexation with cardiolipin in the presence of reactive oxygen species. Blocking access to the heme group has been proposed as an effective intervention method for reducing, if not eliminating, the peroxidase activity of cyt c. In the present study, using a combination of druggability simulations, pharmacophore modeling, virtual screening, and in vitro fluorescence measurements to probe peroxidase activity, we identified three repurposable drugs and seven compounds that are validated to effectively inhibit the peroxidase activity of cyt c. PMID:26078313

  13. Enhancement of Oral Tolerance Induction in DO11.10 Mice by Lactobacillus gasseri OLL2809 via Increase of Effector Regulatory T Cells.

    PubMed

    Aoki-Yoshida, Ayako; Yamada, Kiyoshi; Hachimura, Satoshi; Sashihara, Toshihiro; Ikegami, Shuji; Shimizu, Makoto; Totsuka, Mamoru

    2016-01-01

    Food allergy is a serious problem for infants and young children. Induction of antigen-specific oral tolerance is one therapeutic strategy. Enhancement of oral tolerance induction by diet is a promising strategy to prevent food allergy in infants. Thus, in this study, we evaluate the effect of probiotic Lactobacillus gasseri OLL2809 (LG2809) on oral tolerance induction in a mouse model. The degree of oral tolerance induction was evaluated by measuring the proliferation and level of IL-2 production of splenic CD4+ T cells from DO11.10 mice fed ovalbumin (OVA) alone or OVA with LG2809. Oral administration of LG2809 significantly decreased the rate of proliferation and IL-2 production by CD4+ T cells from OVA-fed mice. LG2809 increased a ratio of CD4+ T-cell population, producing high levels of IL-10 and having strong suppressive activity. Moreover, LG2809 increased a ratio of plasmacytoid dendritic cells (pDCs) among the lamina propria (LP) in small intestine. When used as antigen presenting cells to naïve CD4+ T cells from DO11.10 mice, LP cells from BALB/c mice fed LG2809 induced higher IL-10 production and stronger suppressive activity than those from non-treated mice. These results suggest that oral administration of LG2809 increases the population of pDCs in the LP, resulting in the enhancement of oral tolerance induction by increasing the ratio of effector regulatory T cells. LG2809 could, therefore, act as a potent immunomodulator to prevent food allergies by promoting oral tolerance. PMID:27472281

  14. Enhancement of Oral Tolerance Induction in DO11.10 Mice by Lactobacillus gasseri OLL2809 via Increase of Effector Regulatory T Cells

    PubMed Central

    Aoki-Yoshida, Ayako; Yamada, Kiyoshi; Hachimura, Satoshi; Sashihara, Toshihiro; Ikegami, Shuji; Shimizu, Makoto; Totsuka, Mamoru

    2016-01-01

    Food allergy is a serious problem for infants and young children. Induction of antigen-specific oral tolerance is one therapeutic strategy. Enhancement of oral tolerance induction by diet is a promising strategy to prevent food allergy in infants. Thus, in this study, we evaluate the effect of probiotic Lactobacillus gasseri OLL2809 (LG2809) on oral tolerance induction in a mouse model. The degree of oral tolerance induction was evaluated by measuring the proliferation and level of IL-2 production of splenic CD4+ T cells from DO11.10 mice fed ovalbumin (OVA) alone or OVA with LG2809. Oral administration of LG2809 significantly decreased the rate of proliferation and IL-2 production by CD4+ T cells from OVA-fed mice. LG2809 increased a ratio of CD4+ T-cell population, producing high levels of IL-10 and having strong suppressive activity. Moreover, LG2809 increased a ratio of plasmacytoid dendritic cells (pDCs) among the lamina propria (LP) in small intestine. When used as antigen presenting cells to naïve CD4+ T cells from DO11.10 mice, LP cells from BALB/c mice fed LG2809 induced higher IL-10 production and stronger suppressive activity than those from non-treated mice. These results suggest that oral administration of LG2809 increases the population of pDCs in the LP, resulting in the enhancement of oral tolerance induction by increasing the ratio of effector regulatory T cells. LG2809 could, therefore, act as a potent immunomodulator to prevent food allergies by promoting oral tolerance. PMID:27472281

  15. Over-expression of BvMTSH, a fusion gene for maltooligosyltrehalose synthase and maltooligosyltrehalose trehalohydrolase, enhances drought tolerance in transgenic rice.

    PubMed

    Joo, Joungsu; Choi, Hae Jong; Lee, Youn Hab; Lee, Sarah; Lee, Choong Hwan; Kim, Chung Ho; Cheong, Jong-Joo; Choi, Yang Do; Song, Sang Ik

    2014-01-01

    Plant abiotic stress tolerance has been modulated by engineering the trehalose synthesis pathway. However, many stress-tolerant plants that have been genetically engineered for the trehalose synthesis pathway also show abnormal development. The metabolic intermediate trehalose 6-phosphate has the potential to cause aberrations in growth. To avoid growth inhibition by trehalose 6-phosphate, we used a gene that encodes a bifunctional in-frame fusion (BvMTSH) of maltooligosyltrehalose synthase (BvMTS) and maltooligosyltrehalose trehalohydrolase (BvMTH) from the nonpathogenic bacterium Brevibacterium helvolum. BvMTS converts maltooligosaccharides into maltooligosyltrehalose and BvMTH releases trehalose. Transgenic rice plants that over-express BvMTSH under the control of the constitutive rice cytochrome c promoter (101MTSH) or the ABA-inducible Ai promoter (105MTSH) show enhanced drought tolerance without growth inhibition. Moreover, 101MTSH and 105MTSH showed an ABA-hyposensitive phenotype in the roots. Our results suggest that over-expression of BvMTSH enhances drought-stress tolerance without any abnormal growth and showes ABA hyposensitive phenotype in the roots. PMID:24209631

  16. 2,4,6-Trichlorophenol mediated increases in extracellular peroxidase activity in three species of Lemnaceae.

    PubMed

    Biswas, Dilip K; Scannell, Gillian; Akhmetov, Nurlan; Fitzpatrick, Dara; Jansen, Marcel A K

    2010-11-01

    Chlorinated phenols, or chlorophenols, are persistent priority pollutants that are widespread in the environment. Class III peroxidases are well-characterised plant enzymes that can catalyse the oxidative dechlorination of chlorophenols. Expression of these enzymes by plants is commonly associated with plant stress, therefore limiting scope for phytoremediation. In this study, we have quantitatively compared peroxidase activity and phytotoxicity as a function of 2,4,6-trichlorophenol (TCP) concentration in three species of Lemnaceae; Lemna minor, Lemna gibba and Landoltia punctata. Effects of TCP on the growth rates of the three species differed considerably with L. punctata being the most tolerant species. TCP also affected photosynthetic parameters, causing a decrease in open photosystem II reaction centres (qP) and, in L. punctata only, a decrease in non-photochemical quenching (qN). In parallel, TCP exposure resulted in increased peroxidase activity in all three species. Peroxidase activity in L. minor and L. gibba displayed an inverse relationship with biomass accumulation, i.e. the more growth reduction the more peroxidase activity. In contrast, induction of peroxidase activity in L. punctata was bi-phasic, with a TCP-induced activity peak at concentrations that had no major effect on growth, and further induction under phytotoxic concentrations. The mechanism by which L. punctata recognises and responds to low concentrations of an anthropogenic compound, in the absence of wide-ranging stress, remains enigmatic. However, we conclude that this "window" of peroxidase production in the absence of major growth inhibition offers potential for the development of sustainable, peroxidise-mediated phytoremediation systems. PMID:20810175

  17. Disulfide bonds and glycosylation in fungal peroxidases.

    PubMed

    Limongi, P; Kjalke, M; Vind, J; Tams, J W; Johansson, T; Welinder, K G

    1995-01-15

    Four conserved disulfide bonds and N-linked and O-linked glycans of extracellular fungal peroxidases have been identified from studies of a lignin and a manganese peroxidase from Trametes versicolor, and from Coprinus cinereus peroxidase (CIP) and recombinant C. cinereus peroxidase (rCIP) expressed in Aspergillus oryzae. The eight cysteine residues are linked 1-3, 2-7, 4-5 and 6-8, and are located differently from the four conserved disulfide bridges present in the homologous plant peroxidases. CIP and rCIP were identical in their glycosylation pattern, although the extent of glycan chain heterogeneity depended on the fermentation batch. CIP and rCIP have one N-linked glycan composed only of GlcNAc and Man at residue Asn142, and two O-linked glycans near the C-terminus. The major glycoform consists of single Man residues at Thr331 and at Ser338. T. versicolor lignin isoperoxidase TvLP10 contains a single N-linked glycan composed of (GlcNAc)2Man5 bound to Asn103, whereas (GlcNAc)2Man3 was found in T. versicolor manganese isoperoxidase TvMP2 at the same position. In addition, mass spectrometry of the C-terminal peptide of TvMP2 indicated the presence of five Man residues in O-linked glycans. No phosphate was found in these fungal peroxidases. PMID:7851395

  18. 21 CFR 864.7675 - Leukocyte peroxidase test.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Leukocyte peroxidase test. 864.7675 Section 864... peroxidase test. (a) Identification. A leukocyte peroxidase test is a device used to distinguish certain... peroxidase activity as evidenced by staining. The results of this test are used in the differential...

  19. 21 CFR 864.7675 - Leukocyte peroxidase test.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Leukocyte peroxidase test. 864.7675 Section 864... peroxidase test. (a) Identification. A leukocyte peroxidase test is a device used to distinguish certain... peroxidase activity as evidenced by staining. The results of this test are used in the differential...

  20. 21 CFR 864.7675 - Leukocyte peroxidase test.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Leukocyte peroxidase test. 864.7675 Section 864... peroxidase test. (a) Identification. A leukocyte peroxidase test is a device used to distinguish certain... peroxidase activity as evidenced by staining. The results of this test are used in the differential...

  1. 21 CFR 864.7675 - Leukocyte peroxidase test.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Leukocyte peroxidase test. 864.7675 Section 864... peroxidase test. (a) Identification. A leukocyte peroxidase test is a device used to distinguish certain... peroxidase activity as evidenced by staining. The results of this test are used in the differential...

  2. 21 CFR 864.7675 - Leukocyte peroxidase test.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Leukocyte peroxidase test. 864.7675 Section 864... peroxidase test. (a) Identification. A leukocyte peroxidase test is a device used to distinguish certain... peroxidase activity as evidenced by staining. The results of this test are used in the differential...

  3. Completely automated, highly error-tolerant macromolecular structure determination from multidimensional nuclear overhauser enhancement spectra and chemical shift assignments.

    PubMed

    Kuszewski, John; Schwieters, Charles D; Garrett, Daniel S; Byrd, R Andrew; Tjandra, Nico; Clore, G Marius

    2004-05-26

    The major rate-limiting step in high-throughput NMR protein structure determination involves the calculation of a reliable initial fold, the elimination of incorrect nuclear Overhauser enhancement (NOE) assignments, and the resolution of NOE assignment ambiguities. We present a robust approach to automatically calculate structures with a backbone coordinate accuracy of 1.0-1.5 A from datasets in which as much as 80% of the long-range NOE information (i.e., between residues separated by more than five positions in the sequence) is incorrect. The current algorithm differs from previously published methods in that it has been expressly designed to ensure that the results from successive cycles are not biased by the global fold of structures generated in preceding cycles. Consequently, the method is highly error tolerant and is not easily funnelled down an incorrect path in either three-dimensional structure or NOE assignment space. The algorithm incorporates three main features: a linear energy function representation of the NOE restraints to allow maximization of the number of simultaneously satisfied restraints during the course of simulated annealing; a method for handling the presence of multiple possible assignments for each NOE cross-peak which avoids local minima by treating each possible assignment as if it were an independent restraint; and a probabilistic method to permit both inactivation and reactivation of all NOE restraints on the fly during the course of simulated annealing. NOE restraints are never removed permanently, thereby significantly reducing the likelihood of becoming trapped in a false minimum of NOE assignment space. The effectiveness of the algorithm is demonstrated using completely automatically peak-picked experimental NOE data from two proteins: interleukin-4 (136 residues) and cyanovirin-N (101 residues). The limits of the method are explored using simulated data on the 56-residue B1 domain of Streptococcal protein G. PMID:15149223

  4. A Soybean C2H2-Type Zinc Finger Gene GmZF1 Enhanced Cold Tolerance in Transgenic Arabidopsis

    PubMed Central

    Ma, Xue-Feng; Xu, Zhao-Shi; Liu, Meng-Meng; Shan, Shu-Guang; Cheng, Xian-Guo

    2014-01-01

    Zinc finger proteins were involved in response to different environmental stresses in plant species. A typical Cys2/His2-type (C2H2-type) zinc finger gene GmZF1 from soybean was isolated and was composed of 172 amino acids containing two conserved C2H2-type zinc finger domains. Phylogenetic analysis showed that GmZF1 was clustered on the same branch with six C2H2-type ZFPs from dicotyledonous plants excepting for GsZFP1, and distinguished those from monocotyledon species. The GmZF1 protein was localized at the nucleus, and has specific binding activity with EP1S core sequence, and nucleotide mutation in the core sequence of EPSPS promoter changed the binding ability between GmZF1 protein and core DNA element, implying that two amino acid residues, G and C boxed in core sequence TGACAGTGTCA possibly play positive regulation role in recognizing DNA-binding sites in GmZF1 proteins. High accumulation of GmZF1 mRNA induced by exogenous ABA suggested that GmZF1 was involved in an ABA-dependent signal transduction pathway. Over-expression of GmZF1 significantly improved the contents of proline and soluble sugar and decreased the MDA contents in the transgenic lines exposed to cold stress, indicating that transgenic Arabidopsis carrying GmZF1 gene have adaptive mechanisms to cold stress. Over-expression of GmZF1 also increased the expression of cold-regulated cor6.6 gene by probably recognizing protein-DNA binding sites, suggesting that GmZF1 from soybean could enhance the tolerance of Arabidopsis to cold stress by regulating expression of cold-regulation gene in the transgenic Arabidopsis. PMID:25286048

  5. Enhancement of cadmium tolerance and accumulation by introducing Perilla frutescens (L.) Britt var. frutescens genes in Nicotiana tabacum L. plants.

    PubMed

    Wei, Keqiang; Pang, Shengxi; Yang, Junxian; Wei, Zhizhong

    2015-04-01

    The tobacco has the genetic potential to remove toxic metals from the soil. To develop hyperaccumulating tobacco plants, distant hybridization between tobacco (Nicotiana tabacum L.), a high-biomass crop, and Perilla frutescens (L.) Britt var. frutescens, a newfound Cd-hyperaccumulator species, was carried out using a novel method viz. pollination following grafting. Their hybrid nature was preliminarily confirmed by phenotype, isozyme pattern, random amplified polymorphic DNA (RAPD) and metabolites analysis. About 120 putative F2 hybrids derived from the cross-combination [(N. sylvestris Speg. & Comes rootstock + N. tabacum L. var. 78-04 scion) × P. frutescens (L.) Britt var. frutescens] were then subjected to up to 300 μM CdCl2 in hydroponic conditions for 10 days. Results showed five seedlings were more resistant to Cd than female parent and accumulated 314.6 ± 99.9 mg kg(-1) Cd in their aerial biomass, which was 5.7 times greater than that in "78-04" tobacco (47.2 ± 3.56 mg kg(-1)) (P ≤ 0.05). Two of these seedlings exceeded male parent P. frutescens in the Cd concentration of shoots and reached 424 and 396 mg kg(-1), which was 13% and 6% greater for that of perilla (374.2 ± 10.38 mg kg(-1)), respectively. Compared with parents, two other F2 hybrids tended to accumulate more Cd in the root with bioconcentration factor (BCF) 7.05 and 5.17, respectively. Only one hybrid showed lower Cd concentration but transferred Cd more effectively from the root to the shoot than parents and other F2 hybrids, with the maximum translocation factor (TF) value 1.37. These indicated that the introduction of P. frutescens genes could obviously enhance the cadmium tolerance and accumulation of superior individuals. PMID:25567061

  6. Increasing nitric oxide content in Arabidopsis thaliana by expressing rat neuronal nitric oxide synthase resulted in enhanced stress tolerance.

    PubMed

    Shi, Hai-Tao; Li, Rong-Jun; Cai, Wei; Liu, Wen; Wang, Chao-Lun; Lu, Ying-Tang

    2012-02-01

    Nitric oxide (NO) plays essential roles in many physiological and developmental processes in plants, including biotic and abiotic stresses, which have adverse effects on agricultural production. However, due to the lack of findings regarding nitric oxide synthase (NOS), many difficulties arise in investigating the physiological roles of NO in vivo and thus its utilization for genetic engineering. Here, to explore the possibility of manipulating the endogenous NO level, rat neuronal NOS (nNOS) was expressed in Arabidopsis thaliana. The 35S::nNOS plants showed higher NOS activity and accumulation of NO using the fluorescent probe 3-amino, 4-aminomethyl-2', 7'-difluorescein, diacetate (DAF-FM DA) assay and the hemoglobin assay. Compared with the wild type, the 35S::nNOS plants displayed improved salt and drought tolerance, which was further confirmed by changes in physiological parameters including reduced water loss rate, reduced stomatal aperture, and altered proline and malondialdehyde content. Quantitative real-time PCR analyses revealed that the expression of several stress-regulated genes was up-regulated in the transgenic lines. Furthermore, the transgenic lines also showed enhanced disease resistance against Pseudomonas syringae pv. tomato (Pst) DC3000 by activating the expression of defense-related genes. In addition, we found that the 35S::nNOS lines flowered late by regulating the expression of CO, FLC and LFY genes. Together, these results demonstrated that it is a useful strategy to exploit the roles of plant NO in various processes by the expression of rat nNOS. The approach may also be useful for genetic engineering of crops with increased environmental adaptations. PMID:22186181

  7. Enzymatic removal of paracetamol from aqueous phase: horseradish peroxidase immobilized on nanofibrous membranes.

    PubMed

    Xu, Ran; Si, Yifang; Li, Fengting; Zhang, Bingru

    2015-03-01

    Paracetamol is a widely used as an analgesic and an antipyretic that can easily accumulate in aquatic environments. This study aimed to enhance paracetamol removal efficiency from water by combining the biocatalytic activity of horseradish peroxidase (HRP) with the adsorption of nanofibrous membrane. Poly(vinyl alcohol)/poly(acrylic acid)/SiO2 electrospinning nanofibrous membrane was prepared with fiber diameters of 200 to 300 nm. The membrane was made insoluble by the thermal cross-linking process. HRP, which was previously activated by 1,1'-carbonyldiimidazole, was covalently immobilized on the surface of nanofibers. Immobilized HRP retained 79.4 % of the activity of free HRP. The physical, chemical, and biochemical properties of the immobilized HRP and its application in paracetamol removal were comprehensively investigated. Immobilized HRP showed better storage capability and higher tolerance to the changes in pH and temperature than free HRP. Paracetamol removal rate by immobilized HRP (83.5 %) was similar to that of free HRP (84.4 %), but immobilized HRP showed excellent reusability. The results signify that enzyme immobilized on nanofibers has great application potential in water treatment. PMID:25269844

  8. Tolerating Zero Tolerance?

    ERIC Educational Resources Information Center

    Moore, Brian N.

    2010-01-01

    The concept of zero tolerance dates back to the mid-1990s when New Jersey was creating laws to address nuisance crimes in communities. The main goal of these neighborhood crime policies was to have zero tolerance for petty crime such as graffiti or littering so as to keep more serious crimes from occurring. Next came the war on drugs. In federal…

  9. Overexpression of a maize sulfite oxidase gene in tobacco enhances tolerance to sulfite stress via sulfite oxidation and CAT-mediated H2O2 scavenging.

    PubMed

    Xia, Zongliang; Sun, Kaile; Wang, Meiping; Wu, Ke; Zhang, Hua; Wu, Jianyu

    2012-01-01

    Sulfite oxidase (SO) plays an important role in sulfite metabolism. To date, the molecular mechanisms of sulfite metabolism in plants are largely unknown. Previously, a full-length cDNA of the putative sulfite oxidase gene from maize (ZmSO) was cloned, and its response to SO(2)/sulfite stress at the transcriptional level was characterized. In this study, the recombinant ZmSO protein was purified from E. coli. It exhibited sulfite-dependent activity and had strong affinity for the substrate sulfite. Over-expression (OE) of ZmSO in tobacco plants enhanced their tolerance to sulfite stress. The plants showed much less damage, less sulfite accumulation, but greater amounts of sulfate. This suggests that tolerance of transgenic plants to sulfite was enhanced by increasing SO expression levels. Interestingly, H(2)O(2) accumulation levels by histochemical detection and quantitative determination in the OE plants were much less than those in the wild-type upon sulfite stress. Furthermore, reductions of catalase levels detected in the OE lines were considerably less than in the wild-type plants. This indicates that SO may play an important role in protecting CAT from inhibition by excess sulfite. Collectively, these data demonstrate that transgenic tobacco plants over-expressing ZmSO enhance tolerance to excess sulfite through sulfite oxidation and catalase-mediated hydrogen peroxide scavenging. This is the first SO gene from monocots to be functionally characterized. PMID:22693572

  10. Overexpression of a novel cold-responsive transcript factor LcFIN1 from sheepgrass enhances tolerance to low temperature stress in transgenic plants.

    PubMed

    Gao, Qiong; Li, Xiaoxia; Jia, Junting; Zhao, Pincang; Liu, Panpan; Liu, Zhujiang; Ge, Liangfa; Chen, Shuangyan; Qi, Dongmei; Deng, Bo; Lee, Byung-Hyun; Liu, Gongshe; Cheng, Liqin

    2016-03-01

    As a perennial forage crop broadly distributed in eastern Eurasia, sheepgrass (Leymus chinensis (Trin.) Tzvel) is highly tolerant to low-temperature stress. Previous report indicates that sheepgrass is able to endure as low as -47.5 °C,allowing it to survive through the cold winter season. However, due to the lack of sufficient studies, the underlying mechanism towards the extraordinary low-temperature tolerance is unclear. Although the transcription profiling has provided insight into the transcriptome response to cold stress, more detailed studies are required to dissect the molecular mechanism regarding the excellent abiotic stress tolerance. In this work, we report a novel transcript factor LcFIN1 (L. chinensis freezing-induced 1) from sheepgrass. LcFIN1 showed no homology with other known genes and was rapidly and highly induced by cold stress, suggesting that LcFIN1 participates in the early response to cold stress. Consistently, ectopic expression of LcFIN1 significantly increased cold stress tolerance in the transgenic plants, as indicated by the higher survival rate, fresh weight and other stress-related indexes after a freezing treatment. Transcriptome analysis showed that numerous stress-related genes were differentially expressed in LcFIN1-overexpressing plants, suggesting that LcFIN1 may enhance plant abiotic stress tolerance by transcriptional regulation. Electrophoretic mobility shift assays and CHIP-qPCR showed that LcCBF1 can bind to the CRT/DRE cis-element located in the promoter region of LcFIN1, suggesting that LcFIN1 is directly regulated by LcCBF1. Taken together, our results suggest that LcFIN1 positively regulates plant adaptation response to cold stress and is a promising candidate gene to improve crop cold tolerance. PMID:26234381

  11. Downregulation of miR-219 enhances brain-derived neurotrophic factor production in mouse dorsal root ganglia to mediate morphine analgesic tolerance by upregulating CaMKIIγ

    PubMed Central

    Hu, Xue-Ming; Cao, Shou-Bin; Zhang, Hai-Long; Lyu, Dong-Mei; Chen, Li-Ping; Xu, Heng; Pan, Zhi-Qiang

    2016-01-01

    Background Increasing evidence suggests that microRNAs are functionally involved in the initiation and maintenance of pain hypersensitivity, including chronic morphine analgesic tolerance, through the posttranscriptional regulation of pain-related genes. We have previously demonstrated that miR-219 regulates inflammatory pain in the spinal cord by targeting calcium/calmodulin-dependent protein kinase II gamma (CaMKIIγ). However, whether miR-219 regulates CaMKIIγ expression in the dorsal root ganglia to mediate morphine tolerance remains unclear. Results MiR-219 expression was downregulated and CaMKIIγ expression was upregulated in mouse dorsal root ganglia following chronic morphine treatment. The changes in miR-219 and CaMKIIγ expression closely correlated with the development of morphine tolerance, which was measured using the reduction of percentage of maximum potential efficiency to thermal stimuli. Morphine tolerance was markedly delayed by upregulating miR-219 expression using miR-219 mimics or downregulating CaMKIIγ expression using CaMKIIγ small interfering RNA. The protein and mRNA expression of brain-derived neurotrophic factor were also induced in dorsal root ganglia by prolonged morphine exposure in a time-dependent manner, which were transcriptionally regulated by miR-219 and CaMKIIγ. Scavenging brain-derived neurotrophic factor via tyrosine receptor kinase B-Fc partially attenuated morphine tolerance. Moreover, functional inhibition of miR-219 via miR-219-sponge in naive mice elicited thermal hyperalgesia and spinal neuronal sensitization, which were both suppressed by CaMKIIγ small interfering RNA or tyrosine receptor kinase B-Fc. Conclusions These results demonstrate that miR-219 contributes to the development of chronic tolerance to morphine analgesia in mouse dorsal root ganglia by targeting CaMKIIγ and enhancing CaMKIIγ-dependent brain-derived neurotrophic factor expression. PMID:27599867

  12. Overexpression of Rosa rugosa anthocyanidin reductase enhances tobacco tolerance to abiotic stress through increased ROS scavenging and modulation of ABA signaling.

    PubMed

    Luo, Ping; Shen, Yuxiao; Jin, Shuangxia; Huang, Shasha; Cheng, Xu; Wang, Zhen; Li, Penghui; Zhao, Jian; Bao, Manzhu; Ning, Guogui

    2016-04-01

    Anthocyanidin reductase (ANR) is a key enzyme involved in the biosynthesis of proanthocyanidins (PAs) and plays a role in the plant stress response. However, the mechanism by which ANR confers stress tolerance in plants is not understood. Here, we report the isolation of RrANR, the homologous gene from rose, and NtABF, an ABA-response related transcription factor gene from tobacco. These genes were characterized regarding their functions in stress responses through the use of transgenic, transcriptomic and physiological analyses. Over-expression of RrANR in tobacco resulted in an increased accumulation of both PAs and abscisic acid (ABA), and also enhanced stress tolerance. Transcriptomic analysis of these transgenic tobacco lines indicated that RrANR overexpression induced global transcriptomic changes, including these involved in oxidation/reduction, hormone response and secondary metabolism. Genes related to ABA biosynthesis and reactive oxygen species (ROS)-scavenging were up-regulated in RrANR transgenic lines, and these effects were phenocopied by the direct treatment of tobacco plants with PAs and ABA. Transcriptomic data from each of these treatments identified the upregulation of a putative NtABF. Furthermore, the up-regulation of NtABF in RrANR transformants or in PAs- and ABA-treated tobacco plants was associated with enhanced stress tolerance. Overexpression of NtABF in transgenic tobacco mimicked the effects of RrANR-transgenic plants with regard to the up-regulation of ROS-scavenging genes and an increase in oxidative tolerance. Taken together, our findings indicate that overexpression of RrANR results in an increase in plant tolerance to oxidative stress via increased scavenging of ROS and modulation of the ABA signaling pathway. PMID:26940490

  13. Enhancing Heat Tolerance of the Little Dogwood Cornus canadensis L. f. with Introduction of a Superoxide Reductase Gene from the Hyperthermophilic Archaeon Pyrococcus furiosus

    PubMed Central

    Geng, Xing-Min; Liu, Xiang; Ji, Mikyoung; Hoffmann, William A.; Grunden, Amy; Xiang, Qiu-Yun J.

    2016-01-01

    Production of reactive oxygen species (ROS) can be accelerated under various biotic and abiotic stresses causing lipid peroxidation, protein degradation, enzyme inactivation, and DNA damage. Superoxide reductase (SOR) is a novel antioxidant enzyme from Pyrococcus furiosus and is employed by this anaerobic hyperthermophilic archaeon for efficient detoxification of ROS. In this study, SOR was introduced into a flowering plant Cornus canadensis to enhance its heat tolerance and reduce heat induced damage. A fusion construct of the SOR gene and Green Fluorescent Protein gene (GFP) was introduced into C. canadensis using Agrobacterium-mediated transformation. Heat tolerance of the GFP-SOR expressing transgenic plants was investigated by observing morphological symptoms of heat injury and by examining changes in photosynthesis, malondialdehyde (MDA), and proline levels in the plants. Our results indicate that the expression of the P. furiosus SOR gene in the transgenic plants alleviated lipid peroxidation of cell membranes and photoinhibition of PS II, and decreased the accumulation of proline at 40°C. After a series of exposures to increasing temperatures, the SOR transgenic plants remained healthy and green whereas most of the non-transgenic plants dried up and were unable to recover. While it had previously been reported that expression of SOR in Arabidopsis enhanced heat tolerance, this is the first report of the successful demonstration of improved heat tolerance in a non-model plant resulting from the introduction of P. furiosus SOR. The study demonstrates the potential of SOR for crop improvement and that inherent limitations of plant heat tolerance can be ameliorated with P. furiosus SOR. PMID:26858741

  14. Enhancing the aluminium tolerance of barley by expressing the citrate transporter genes SbMATE and FRD3.

    PubMed

    Zhou, Gaofeng; Pereira, Jorge F; Delhaize, Emmanuel; Zhou, Meixue; Magalhaes, Jurandir V; Ryan, Peter R

    2014-06-01

    Malate and citrate efflux from root apices is a mechanism of Al(3+) tolerance in many plant species. Citrate efflux is facilitated by members of the MATE (multidrug and toxic compound exudation) family localized to the plasma membrane of root cells. Barley (Hordeum vulgare) is among the most Al(3+)-sensitive cereal species but the small genotypic variation in tolerance that is present is correlated with citrate efflux via a MATE transporter named HvAACT1. This study used a biotechnological approach to increase the Al(3+) tolerance of barley by transforming it with two MATE genes that encode citrate transporters: SbMATE is the major Al(3+)-tolerance gene from sorghum whereas FRD3 is involved with Fe nutrition in Arabidopsis. Independent transgenic and null T3 lines were generated for both transgenes. Lines expressing SbMATE showed Al(3+)-activated citrate efflux from root apices and greater tolerance to Al(3+) toxicity than nulls in hydroponic and short-term soil trials. Transgenic lines expressing FRD3 exhibited similar phenotypes except citrate release from roots occurred constitutively. The Al(3+) tolerance of these lines was compared with previously generated transgenic barley lines overexpressing the endogenous HvAACT1 gene and the TaALMT1 gene from wheat. Barley lines expressing TaALMT1 showed significantly greater Al(3+) tolerance than all lines expressing MATE genes. This study highlights the relative efficacy of different organic anion transport proteins for increasing the Al(3+) tolerance of an important crop species. PMID:24692647

  15. Dietary alpha-ketoglutarate increases cold tolerance in Drosophila melanogaster and enhances protein pool and antioxidant defense in sex-specific manner.

    PubMed

    Bayliak, Maria M; Lylyk, Maria P; Shmihel, Halyna V; Sorochynska, Oksana M; Manyukh, Oksana V; Pierzynowski, Stefan G; Lushchak, Volodymyr I

    2016-08-01

    Alpha-ketoglutarate (AKG) is an important intermediate in Krebs cycle which bridges the metabolism of amino acids and carbohydrates. Its effects as a dietary supplement on cold tolerance were studied in Drosophila melanogaster Canton S. Two-day-old adult flies fed at larval and adult stages with AKG at moderate concentrations (5-10mM) recovered faster from chill coma (0°C for 15min or 3h) than control ones. The beneficial effect of AKG on chill coma recovery was not found at its higher concentrations, which suggests hormetic like action of this keto acid. Time of 50% observed mortality after 2h recovery from continuous cold exposure (-1°C for 3-31h) (LTi50) was higher for flies reared on 10mM AKG compared with control ones, showing that the diet with AKG enhanced insect cold tolerance. In parallel with enhancement of cold tolerance, dietary AKG improved fly locomotor activity. Metabolic effects of AKG differed partly in males and females. In males fed on AKG, there were no differences in total protein and free amino acid levels, but the total antioxidant capacity, catalase activity and low molecular mass thiol content were higher than in control animals. In females, dietary AKG promoted higher total antioxidant capacity and higher levels of proteins, total amino acids, proline and low molecular mass thiols. The levels of lipid peroxides were lower in both fly sexes reared on AKG as compared with control ones. We conclude that both enhancement of antioxidant system capacity and synthesis of amino acids can be important for AKG-promoted cold tolerance in D. melanogaster. The involvement of AKG in metabolic pathways of Drosophila males and females is discussed. PMID:27503710

  16. (Molecular characteristics of the lignin forming peroxidase)

    SciTech Connect

    Lagrimini, L.M.

    1990-01-01

    Since this manuscript was submitted we have conducted a more thorough physiological analysis of water relations in wild-type and peroxidase overproducing plants. These experiments include pressure bomb, plasmolysis, and membrane integrity analysis. We are also in the process of analyzing other phenotypes in peroxidase overproducer plants such as excessive browning of tissue, the rapid death of tissue in culture, and poor germination of seed. Transformed plants of Nicotiana tabacum and Nicotiana sylvestris were obtained which have peroxidase activity 3--7 fold lower than wild-type plants. This was done by introducing a chimeric gene composed of the CaMV 35S promoter and the 5' half of the tobacco anionic peroxidase cDNA in the antisense RNA configuration. A manuscript which describes this work is being written, and will be submitted for publication in January 1990. The anionic peroxidase gene has been cloned by hybridization to the cloned cDNA. The entire gene is contained on an 8.7kb fragment within a lambda phage clone. Several smaller DNA fragments have been subcloned, and some have been sequenced. One exon within the coding sequence has been sequenced, along with the partial sequence of two introns. Further sequencing is being carried-out to identify the promoter, which will be later joined to a reporter gene. 6 figs.

  17. Overexpression of the Maize psbA Gene Enhances Drought Tolerance Through Regulating Antioxidant System, Photosynthetic Capability, and Stress Defense Gene Expression in Tobacco.

    PubMed

    Huo, Yongjin; Wang, Meiping; Wei, Yangyang; Xia, Zongliang

    2015-01-01

    The psbA (encoding D1 protein) plays an important role in protecting photosystem II (PSII) from oxidative damage in higher plants. In our previous study, the role of the psbA from maize (Zea mays. L) in response to SO2 stress was characterized. To date, information about the involvement of the psbA gene in drought response is scarce. Here we found that overexpression (OE) of ZmpsbA showed increased D1 protein abundance and enhanced drought stress tolerance in tobacco. The drought-tolerant phenotypes of the OE lines were accompanied by increases of key antioxidant enzymes SOD, CAT, and POD activities, but decreases of hydrogen peroxide, malondialdehyde, and ion leakage. Further investigation showed that the OE plants had much less reductions than the wild-type in the net photosynthesis rate (Pn), stomatal conductance (Gs), and the maximal photochemical efficiency of PSII (Fv/Fm) during drought stress; indicating that OE of ZmpsbA may alleviate photosynthesis inhibition during drought. qRT-PCR analysis revealed that there was significantly increased expression of NtLEA5, NtERD10C, NtAREB, and NtCDPK2 in ZmpsbA-OE lines. Together, our results indicate that ZmpsbA improves drought tolerance in tobacco possibly by alleviating photosynthesis reduction, reducing reactive oxygen species accumulation and membrane damage, and modulating stress defense gene expression. ZmpsbA could be exploited for engineering drought-tolerant plants in molecular breeding of crops. PMID:26793207

  18. Overexpression of a bHLH1 Transcription Factor of Pyrus ussuriensis Confers Enhanced Cold Tolerance and Increases Expression of Stress-Responsive Genes

    PubMed Central

    Jin, Cong; Huang, Xiao-San; Li, Kong-Qing; Yin, Hao; Li, Lei-Ting; Yao, Zheng-Hong; Zhang, Shao-Ling

    2016-01-01

    The basic helix-loop-helix (bHLH) transcription factors are involved in arrays of physiological and biochemical processes. However, knowledge concerning the functions of bHLHs in cold tolerance remains poorly understood. In this study, a PubHLH1 gene isolated from Pyrus ussuriensis was characterized for its function in cold tolerance. PubHLH1 was upregulated by cold, salt, and dehydration, with the greatest induction under cold conditions. PubHLH1 had the transactivational activity and localized in the nucleus. Ectopic expression of PubHLH1 in transgenic tobacco conferred enhanced tolerance to cold stress. The transgenic lines had higher survival rates, higher chlorophyll, higher proline contents, lower electrolyte leakages and MDA when compared with wild type (WT). In addition, transcript levels of eight genes associated with ROS scavenging, regulation, and stress defense were higher in the transgenic plants relative to the WT under the chilling stress. Taken together, these results demonstrated that PubHLH1 played a key role in cold tolerance and, at least in part, contributed to activation of stress-responsive genes. PMID:27092159

  19. MdVHP1 encodes an apple vacuolar H(+)-PPase and enhances stress tolerance in transgenic apple callus and tomato.

    PubMed

    Dong, Qing-Long; Liu, Dan-Dan; An, Xiu-Hong; Hu, Da-Gang; Yao, Yu-Xin; Hao, Yu-Jin

    2011-11-15

    Vacuolar H(+)-translocating inorganic pyrophosphatase (VHP, EC 3.6.1.1) is an electrogenic proton pump, which is related to growth as well as abiotic stress tolerance in plants. In this study, a VHP gene MdVHP1 was isolated from apple. The alignment of nucleotide and amino acid sequences showed that it encoded a type I VHP protein. It expressed in vegetative and reproductive organs, and its expression was induced by salt, PEG-mediated osmotic stress, cold and heat in apple in vitro shoot cultures. MdVHP1 expression showed a similar pattern in different apple tissues, but different change dynamics in response to abiotic stresses, compared with MdVHP2 (another MdVHP gene in apple). MdVHP1 overexpression enhanced tolerance to salt, PEG-mimic drought, cold and heat in transgenic apple calluses, which was related to an increased accumulation of proline and decreased MDA content compared with control calluses. In addition, MdVHP1 overexpression confers improved tolerance to salt and drought in transgenic tomato, along with an increased ion accumulation, high RWC and low solute potential compared with wild type. These results indicate that MdVHP1 is an important regulator for plant tolerance to abiotic stresses by modulating internal stores of ions and solutes. PMID:21840622

  20. Overexpression of a bHLH1 Transcription Factor of Pyrus ussuriensis Confers Enhanced Cold Tolerance and Increases Expression of Stress-Responsive Genes.

    PubMed

    Jin, Cong; Huang, Xiao-San; Li, Kong-Qing; Yin, Hao; Li, Lei-Ting; Yao, Zheng-Hong; Zhang, Shao-Ling

    2016-01-01

    The basic helix-loop-helix (bHLH) transcription factors are involved in arrays of physiological and biochemical processes. However, knowledge concerning the functions of bHLHs in cold tolerance remains poorly understood. In this study, a PubHLH1 gene isolated from Pyrus ussuriensis was characterized for its function in cold tolerance. PubHLH1 was upregulated by cold, salt, and dehydration, with the greatest induction under cold conditions. PubHLH1 had the transactivational activity and localized in the nucleus. Ectopic expression of PubHLH1 in transgenic tobacco conferred enhanced tolerance to cold stress. The transgenic lines had higher survival rates, higher chlorophyll, higher proline contents, lower electrolyte leakages and MDA when compared with wild type (WT). In addition, transcript levels of eight genes associated with ROS scavenging, regulation, and stress defense were higher in the transgenic plants relative to the WT under the chilling stress. Taken together, these results demonstrated that PubHLH1 played a key role in cold tolerance and, at least in part, contributed to activation of stress-responsive genes. PMID:27092159

  1. Involvement of the leaf antioxidant system in the response to soil flooding in two Trifolium genotypes differing in their tolerance to waterlogging.

    PubMed

    Simova-Stoilova, L; Demirevska, K; Kingston-Smith, A; Feller, U

    2012-02-01

    A comparative study of the response to waterlogging in a tolerant (Trifolium repens L., white clover cultivar Rivendel) and susceptible (Trifolium pratense L., red clover cultivar Raya) plants was undertaken to reveal the possible link between plant performance and oxidative stress protection mechanisms in leaves. Two weeks of soil waterlogging induced visible leaf damage in the susceptible genotype. In the tolerant one, signs of stress suffering appeared a week later. Waterlogging induced hydrogen peroxide accumulation in both clover species. The content of lipid hydroperoxides markedly increased in the sensitive plants along with stress prolongation, while in the tolerant ones their initial rise was followed by return to control levels. In the leaves of both genotypes ascorbic acid content increased following treatment, accompanied by transient increase in oxidized ascorbate. Superoxide dismutase (SOD) isoforms responded differently to the treatment, CuZn SOD isoforms being inhibited; catalase activity diminished while peroxidase activity increased and a new peroxidase isoform was detected after prolonged waterlogging in both clover species. Results support more pronounced oxidative secondary stress in red clover leaves as a result of waterlogging with progressively increased oxidative membrane injury, protein loss, and peroxidase activity enhancement. White clover presented relative protein stability and earlier and more active ascorbate involvement in the antioxidative protection. PMID:22195576

  2. An emphasis of hydrogen sulfide-cysteine cycle on enhancing the tolerance to chromium stress in Arabidopsis.

    PubMed

    Fang, Huihui; Liu, Zhiqiang; Jin, Zhuping; Zhang, Liping; Liu, Danmei; Pei, Yanxi

    2016-06-01

    Increasing attention has been focused on the health of vegetables and grains grown in the contaminated agricultural soil, it is thus meaningful to find ways to reduce the heavy metals (HMs) accumulation in plants. As sulfur is considered to be an essential macronutrient for plant stress defenses, the important role of sulfur assimilation in plants responding to HMs stress has been followed. However, the potential mechanism of the only sulfur-containing gasotransmitter hydrogen sulfide (H2S) and its main endogenously generated substrate, cysteine (Cys), in plant defense is poorly understood. The physiological and biochemical methods together with qRT-PCR were used to explore the response pattern of H2S-Cys cycle in plants resisting to chromium (Cr(6+)) stress. Our results suggested that Cr(6+) stress inhibited Arabidopsis root elongation, increased the H2S and Cys contents time-dependently, and H2S production was activated earlier than Cys. Furthermore, H2S increased Cys accumulation more quickly than Cr(6+) stress. The qRT-PCR results revealed that H2S up-regulated the Cys generation-related genes OASTLa, SAT1 and SAT5 expression levels, and that SAT1 and SAT5 expression was elevated for a longer duration. Data suggested that H2S might regulate Cys metabolism-related genes expression to participate in Cr(6+)-mediated Cys accumulation. H2S and Cys relieved the root elongation inhibition caused by Cr(6+) in Arabidopsis. Both H2S and Cys enhanced glutathione generation and activated phytochelatins (PCs) synthesis by up-regulating PCS1 and PCS2 expression levels to fight against Cr(6+) stress. Besides regulating the expression of PCs synthase encoding genes, H2S might promote metallothioneins accumulation by significantly increasing the MT2A gene expression. Overall, H2S and H2S-induced Cys accumulation (H2S-Cys system) was critical in imparting Cr(6+) tolerance in Arabidopsis. This paper is the first to indicate that gasotransmitter H2S induced Cys accumulation in

  3. Radiation induces acid tolerance of Clostridium tyrobutyricum and enhances bioproduction of butyric acid through a metabolic switch

    PubMed Central

    2014-01-01

    Background Butyric acid as a renewable resource has become an increasingly attractive alternative to petroleum-based fuels. Clostridium tyrobutyricum ATCC 25755T is well documented as a fermentation strain for the production of acids. However, it has been reported that butyrate inhibits its growth, and the accumulation of acetate also inhibits biomass synthesis, making production of butyric acid from conventional fermentation processes economically challenging. The present study aimed to identify whether irradiation of C. tyrobutyricum cells makes them more tolerant to butyric acid inhibition and increases the production of butyrate compared with wild type. Results In this work, the fermentation kinetics of C. tyrobutyricum cultures after being classically adapted for growth at 3.6, 7.2 and 10.8 g·L-1 equivalents were studied. The results showed that, regardless of the irradiation used, there was a gradual inhibition of cell growth at butyric acid concentrations above 10.8 g·L-1, with no growth observed at butyric acid concentrations above 3.6 g·L-1 for the wild-type strain during the first 54 h of fermentation. The sodium dodecyl sulfate polyacrylamide gel electrophoresis also showed significantly different expression levels of proteins with molecular mass around the wild-type and irradiated strains. The results showed that the proportion of proteins with molecular weights of 85 and 106 kDa was much higher for the irradiated strains. The specific growth rate decreased by 50% (from 0.42 to 0.21 h-1) and the final concentration of butyrate increased by 68% (from 22.7 to 33.4 g·L-1) for the strain irradiated at 114 AMeV and 40 Gy compared with the wild-type strains. Conclusions This study demonstrates that butyric acid production from glucose can be significantly improved and enhanced by using 12C6+ heavy ion-irradiated C. tyrobutyricum. The approach is economical, making it competitive compared with similar fermentation processes. It may prove useful as

  4. Acclimatization to high-variance habitats does not enhance physiological tolerance of two key Caribbean corals to future temperature and pH.

    PubMed

    Camp, Emma F; Smith, David J; Evenhuis, Chris; Enochs, Ian; Manzello, Derek; Woodcock, Stephen; Suggett, David J

    2016-05-25

    Corals are acclimatized to populate dynamic habitats that neighbour coral reefs. Habitats such as seagrass beds exhibit broad diel changes in temperature and pH that routinely expose corals to conditions predicted for reefs over the next 50-100 years. However, whether such acclimatization effectively enhances physiological tolerance to, and hence provides refuge against, future climate scenarios remains unknown. Also, whether corals living in low-variance habitats can tolerate present-day high-variance conditions remains untested. We experimentally examined how pH and temperature predicted for the year 2100 affects the growth and physiology of two dominant Caribbean corals (Acropora palmata and Porites astreoides) native to habitats with intrinsically low (outer-reef terrace, LV) and/or high (neighbouring seagrass, HV) environmental variance. Under present-day temperature and pH, growth and metabolic rates (calcification, respiration and photosynthesis) were unchanged for HV versus LV populations. Superimposing future climate scenarios onto the HV and LV conditions did not result in any enhanced tolerance to colonies native to HV. Calcification rates were always lower for elevated temperature and/or reduced pH. Together, these results suggest that seagrass habitats may not serve as refugia against climate change if the magnitude of future temperature and pH changes is equivalent to neighbouring reef habitats. PMID:27194698

  5. ICE1 of Pyrus ussuriensis functions in cold tolerance by enhancing PuDREBa transcriptional levels through interacting with PuHHP1.

    PubMed

    Huang, Xiaosan; Li, Kongqing; Jin, Cong; Zhang, Shaoling

    2015-01-01

    ICE1 transcription factor plays an important role in plant cold stress via regulating the expression of stress-responsive genes. In this study, a PuICE1 gene isolated from Pyrus ussuriensis was characterized for its function in cold tolerance. The expression levels of the PuICE1 were induced by cold, dehydration and salt, with the greatest induction under cold conditions. PuICE1 was localized in the nucleus and could bind specifically to the MYC element in the PuDREBa promoter. The PuICE1 fused to the GAL4 DNA-binding domain to have transcriptional activation activity. Ectopic expression of the PuICE1 in tomato conferred enhanced tolerance to cold stress at cold temperatures, less electrolyte leakage, less MDA content, higher chlorophyll content, higher survival rate, higher proline content, higher activities of enzymes. In additon, steady-state mRNA levels of six stress-responsive genes coding for either functional or regulatory genes were induced to higher levels in the transgenic lines by cold stress. Yeast two-hybrid, transient assay, split luciferase complementation and BiFC assays all revealed that PuHHP1 protein can physically interact with PuICE1. Taken together, these results demonstrated that PuICE1 plays a positive role in cold tolerance, which may be due to enhancement of PuDREBa transcriptional levels through interacting with the PuHHP1. PMID:26626798

  6. ICE1 of Pyrus ussuriensis functions in cold tolerance by enhancing PuDREBa transcriptional levels through interacting with PuHHP1

    PubMed Central

    Huang, Xiaosan; Li, Kongqing; Jin, Cong; Zhang, Shaoling

    2015-01-01

    ICE1 transcription factor plays an important role in plant cold stress via regulating the expression of stress-responsive genes. In this study, a PuICE1 gene isolated from Pyrus ussuriensis was characterized for its function in cold tolerance. The expression levels of the PuICE1 were induced by cold, dehydration and salt, with the greatest induction under cold conditions. PuICE1 was localized in the nucleus and could bind specifically to the MYC element in the PuDREBa promoter. The PuICE1 fused to the GAL4 DNA-binding domain to have transcriptional activation activity. Ectopic expression of the PuICE1 in tomato conferred enhanced tolerance to cold stress at cold temperatures, less electrolyte leakage, less MDA content, higher chlorophyll content, higher survival rate, higher proline content, higher activities of enzymes. In additon, steady-state mRNA levels of six stress-responsive genes coding for either functional or regulatory genes were induced to higher levels in the transgenic lines by cold stress. Yeast two-hybrid, transient assay, split luciferase complementation and BiFC assays all revealed that PuHHP1 protein can physically interact with PuICE1. Taken together, these results demonstrated that PuICE1 plays a positive role in cold tolerance, which may be due to enhancement of PuDREBa transcriptional levels through interacting with the PuHHP1. PMID:26626798

  7. ICE1 of Pyrus ussuriensis functions in cold tolerance by enhancing PuDREBa transcriptional levels through interacting with PuHHP1

    NASA Astrophysics Data System (ADS)

    Huang, Xiaosan; Li, Kongqing; Jin, Cong; Zhang, Shaoling

    2015-12-01

    ICE1 transcription factor plays an important role in plant cold stress via regulating the expression of stress-responsive genes. In this study, a PuICE1 gene isolated from Pyrus ussuriensis was characterized for its function in cold tolerance. The expression levels of the PuICE1 were induced by cold, dehydration and salt, with the greatest induction under cold conditions. PuICE1 was localized in the nucleus and could bind specifically to the MYC element in the PuDREBa promoter. The PuICE1 fused to the GAL4 DNA-binding domain to have transcriptional activation activity. Ectopic expression of the PuICE1 in tomato conferred enhanced tolerance to cold stress at cold temperatures, less electrolyte leakage, less MDA content, higher chlorophyll content, higher survival rate, higher proline content, higher activities of enzymes. In additon, steady-state mRNA levels of six stress-responsive genes coding for either functional or regulatory genes were induced to higher levels in the transgenic lines by cold stress. Yeast two-hybrid, transient assay, split luciferase complementation and BiFC assays all revealed that PuHHP1 protein can physically interact with PuICE1. Taken together, these results demonstrated that PuICE1 plays a positive role in cold tolerance, which may be due to enhancement of PuDREBa transcriptional levels through interacting with the PuHHP1.

  8. Modelling a Peroxidase-based Optical Biosensor

    PubMed Central

    Baronas, Romas; Gaidamauskaite, Evelina; Kulys, Juozas

    2007-01-01

    The response of a peroxidase-based optical biosensor was modelled digitally. A mathematical model of the optical biosensor is based on a system of non-linear reaction-diffusion equations. The modelling biosensor comprises two compartments, an enzyme layer and an outer diffusion layer. The digital simulation was carried out using finite difference technique. The influence of the substrate concentration as well as of the thickness of both the enzyme and diffusion layers on the biosensor response was investigated. Calculations showed complex kinetics of the biosensor response, especially at low concentrations of the peroxidase and of the hydrogen peroxide.

  9. Malate Synthesis and Secretion Mediated by a Manganese-Enhanced Malate Dehydrogenase Confers Superior Manganese Tolerance in Stylosanthes guianensis1

    PubMed Central

    Chen, Zhijian; Sun, Lili; Liu, Pandao; Liu, Guodao; Tian, Jiang; Liao, Hong

    2015-01-01

    Manganese (Mn) toxicity is a major constraint limiting plant growth on acidic soils. Superior Mn tolerance in Stylosanthes spp. has been well documented, but its molecular mechanisms remain largely unknown. In this study, superior Mn tolerance in Stylosanthes guianensis was confirmed, as reflected by a high Mn toxicity threshold. Furthermore, genetic variation of Mn tolerance was evaluated using two S. guianensis genotypes, which revealed that the Fine-stem genotype had higher Mn tolerance than the TPRC2001-1 genotype, as exhibited through less reduction in dry weight under excess Mn, and accompanied by lower internal Mn concentrations. Interestingly, Mn-stimulated increases in malate concentrations and exudation rates were observed only in the Fine-stem genotype. Proteomic analysis of Fine-stem roots revealed that S. guianensis Malate Dehydrogenase1 (SgMDH1) accumulated in response to Mn toxicity. Western-blot and quantitative PCR analyses showed that Mn toxicity resulted in increased SgMDH1 accumulation only in Fine-stem roots, but not in TPRC2001-1. The function of SgMDH1-mediated malate synthesis was verified through in vitro biochemical analysis of SgMDH1 activities against oxaloacetate, as well as in vivo increased malate concentrations in yeast (Saccharomyces cerevisiae), soybean (Glycine max) hairy roots, and Arabidopsis (Arabidopsis thaliana) with SgMDH1 overexpression. Furthermore, SgMDH1 overexpression conferred Mn tolerance in Arabidopsis, which was accompanied by increased malate exudation and reduced plant Mn concentrations, suggesting that secreted malate could alleviate Mn toxicity in plants. Taken together, we conclude that the superior Mn tolerance of S. guianensis is achieved by coordination of internal and external Mn detoxification through malate synthesis and exudation, which is regulated by SgMDH1 at both transcription and protein levels. PMID:25378694

  10. Maize aluminum tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize is one of the most economically important food crops grown on acid soils, where aluminum (Al) toxicity greatly limits crop yields. Considerable variation for Al tolerance exists in maize, and this variation has been exploited for many years by plant breeders to enhance maize Al tolerance. Curr...

  11. Overexpression of AtEDT1/HDG11 in Chinese Kale (Brassica oleracea var. alboglabra) Enhances Drought and Osmotic Stress Tolerance.

    PubMed

    Zhu, Zhangsheng; Sun, Binmei; Xu, Xiaoxia; Chen, Hao; Zou, Lifang; Chen, Guoju; Cao, Bihao; Chen, Changming; Lei, Jianjun

    2016-01-01

    Plants are constantly challenged by environmental stresses, including drought and high salinity. Improvement of drought and osmotic stress tolerance without yield decrease has been a great challenge in crop improvement. The Arabidopsis ENHANCED DROUGHT TOLERANCE1/HOMEODOMAIN GLABROUS11 (AtEDT1/HDG11), a protein of the class IV HD-Zip family, has been demonstrated to significantly improve drought tolerance in Arabidopsis, rice, and pepper. Here, we report that AtEDT1/HDG11 confers drought and osmotic stress tolerance in the Chinese kale. AtEDT1/HDG11-overexpression lines exhibit auxin-overproduction phenotypes, such as long hypocotyls, tall stems, more root hairs, and a larger root system architecture. Compared with the untransformed control, transgenic lines have significantly reduced stomatal density. In the leaves of transgenic Chinese kale plants, proline (Pro) content and reactive oxygen species-scavenging enzyme activity was significantly increased after drought and osmotic stress, particularly compared to wild kale. More importantly, AtEDT1/HDG11-overexpression leads to abscisic acid (ABA) hypersensitivity, resulting in ABA inhibitor germination and induced stomatal closure. Consistent with observed phenotypes, the expression levels of auxin, ABA, and stress-related genes were also altered under both normal and/or stress conditions. Further analysis showed that AtEDT1/HDG11, as a transcription factor, can target the auxin biosynthesis gene YUCC6 and ABA response genes ABI3 and ABI5. Collectively, our results provide a new insight into the role of AtEDT1/HDG11 in enhancing abiotic stress resistance through auxin- and ABA-mediated signaling response in Chinese kale. PMID:27625663

  12. Overexpression of AtEDT1/HDG11 in Chinese Kale (Brassica oleracea var. alboglabra) Enhances Drought and Osmotic Stress Tolerance

    PubMed Central

    Zhu, Zhangsheng; Sun, Binmei; Xu, Xiaoxia; Chen, Hao; Zou, Lifang; Chen, Guoju; Cao, Bihao; Chen, Changming; Lei, Jianjun

    2016-01-01

    Plants are constantly challenged by environmental stresses, including drought and high salinity. Improvement of drought and osmotic stress tolerance without yield decrease has been a great challenge in crop improvement. The Arabidopsis ENHANCED DROUGHT TOLERANCE1/HOMEODOMAIN GLABROUS11 (AtEDT1/HDG11), a protein of the class IV HD-Zip family, has been demonstrated to significantly improve drought tolerance in Arabidopsis, rice, and pepper. Here, we report that AtEDT1/HDG11 confers drought and osmotic stress tolerance in the Chinese kale. AtEDT1/HDG11-overexpression lines exhibit auxin-overproduction phenotypes, such as long hypocotyls, tall stems, more root hairs, and a larger root system architecture. Compared with the untransformed control, transgenic lines have significantly reduced stomatal density. In the leaves of transgenic Chinese kale plants, proline (Pro) content and reactive oxygen species-scavenging enzyme activity was significantly increased after drought and osmotic stress, particularly compared to wild kale. More importantly, AtEDT1/HDG11-overexpression leads to abscisic acid (ABA) hypersensitivity, resulting in ABA inhibitor germination and induced stomatal closure. Consistent with observed phenotypes, the expression levels of auxin, ABA, and stress-related genes were also altered under both normal and/or stress conditions. Further analysis showed that AtEDT1/HDG11, as a transcription factor, can target the auxin biosynthesis gene YUCC6 and ABA response genes ABI3 and ABI5. Collectively, our results provide a new insight into the role of AtEDT1/HDG11 in enhancing abiotic stress resistance through auxin- and ABA-mediated signaling response in Chinese kale. PMID:27625663

  13. Widespread occurrence of expressed fungal secretory peroxidases in forest soils.

    PubMed

    Kellner, Harald; Luis, Patricia; Pecyna, Marek J; Barbi, Florian; Kapturska, Danuta; Krüger, Dirk; Zak, Donald R; Marmeisse, Roland; Vandenbol, Micheline; Hofrichter, Martin

    2014-01-01

    Fungal secretory peroxidases mediate fundamental ecological functions in the conversion and degradation of plant biomass. Many of these enzymes have strong oxidizing activities towards aromatic compounds and are involved in the degradation of plant cell wall (lignin) and humus. They comprise three major groups: class II peroxidases (including lignin peroxidase, manganese peroxidase, versatile peroxidase and generic peroxidase), dye-decolorizing peroxidases, and heme-thiolate peroxidases (e.g. unspecific/aromatic peroxygenase, chloroperoxidase). Here, we have repeatedly observed a widespread expression of all major peroxidase groups in leaf and needle litter across a range of forest ecosystems (e.g. Fagus, Picea, Acer, Quercus, and Populus spp.), which are widespread in Europe and North America. Manganese peroxidases and unspecific peroxygenases were found expressed in all nine investigated forest sites, and dye-decolorizing peroxidases were observed in five of the nine sites, thereby indicating biological significance of these enzymes for fungal physiology and ecosystem processes. Transcripts of selected secretory peroxidase genes were also analyzed in pure cultures of several litter-decomposing species and other fungi. Using this information, we were able to match, in environmental litter samples, two manganese peroxidase sequences to Mycena galopus and Mycena epipterygia and one unspecific peroxygenase transcript to Mycena galopus, suggesting an important role of this litter- and coarse woody debris-dwelling genus in the disintegration and transformation of litter aromatics and organic matter formation. PMID:24763280

  14. Widespread Occurrence of Expressed Fungal Secretory Peroxidases in Forest Soils

    PubMed Central

    Kellner, Harald; Luis, Patricia; Pecyna, Marek J.; Barbi, Florian; Kapturska, Danuta; Krüger, Dirk; Zak, Donald R.; Marmeisse, Roland; Vandenbol, Micheline; Hofrichter, Martin

    2014-01-01

    Fungal secretory peroxidases mediate fundamental ecological functions in the conversion and degradation of plant biomass. Many of these enzymes have strong oxidizing activities towards aromatic compounds and are involved in the degradation of plant cell wall (lignin) and humus. They comprise three major groups: class II peroxidases (including lignin peroxidase, manganese peroxidase, versatile peroxidase and generic peroxidase), dye-decolorizing peroxidases, and heme-thiolate peroxidases (e.g. unspecific/aromatic peroxygenase, chloroperoxidase). Here, we have repeatedly observed a widespread expression of all major peroxidase groups in leaf and needle litter across a range of forest ecosystems (e.g. Fagus, Picea, Acer, Quercus, and Populus spp.), which are widespread in Europe and North America. Manganese peroxidases and unspecific peroxygenases were found expressed in all nine investigated forest sites, and dye-decolorizing peroxidases were observed in five of the nine sites, thereby indicating biological significance of these enzymes for fungal physiology and ecosystem processes. Transcripts of selected secretory peroxidase genes were also analyzed in pure cultures of several litter-decomposing species and other fungi. Using this information, we were able to match, in environmental litter samples, two manganese peroxidase sequences to Mycena galopus and Mycena epipterygia and one unspecific peroxygenase transcript to Mycena galopus, suggesting an important role of this litter- and coarse woody debris-dwelling genus in the disintegration and transformation of litter aromatics and organic matter formation. PMID:24763280

  15. Calcium promotes activity and confers heat stability on plant peroxidases

    PubMed Central

    Plieth, Christoph; Vollbehr, Sonja

    2012-01-01

    In this paper we demonstrate how peroxidase (PO) activities and their heat stability correlate with the availability of free Ca2+ ions. Calcium ions work as a molecular switch for PO activity and exert a protective function, rendering POs heat stable. The concentration ranges of these two activities differ markedly. POs are activated by µM Ca2+ concentration ranges, whereas heat stabilization is observed in the nM range. This suggests the existence of different Ca2+ binding sites. The heat stability of POs depends on the source plant species. Terrestrial plants have POs that exhibit higher temperature stability than those POs from limnic and marine plants. Different POs from a single species can differ in terms of heat stability. The abundance of different POs within a plant is dependent on age and developmental stage. The heat stability of a PO does not necessarily correlate with the maximum temperature the source species is usually exposed to in its natural habitat. This raises questions on the role of POs in the heat tolerance of plants. Consequently, detailed investigations are needed to identify and characterize individual POs, with regard to their genetic origin, subcellular expression, tissue abundance, developmental emergence and their functions in innate and acquired heat tolerance. PMID:22580695

  16. Guaiacol Peroxidase Zymography for the Undergraduate Laboratory

    ERIC Educational Resources Information Center

    Wilkesman, Jeff; Castro, Diana; Contreras, Lellys M.; Kurz, Liliana

    2014-01-01

    This laboratory exercise presents a novel way to introduce undergraduate students to the specific detection of enzymatic activity by electrophoresis. First, students prepare a crude peroxidase extract and then analyze the homogenate via electrophoresis. Zymography, that is, a SDS-PAGE method to detect enzyme activity, is used to specifically…

  17. Microfluidic peroxidase biochip for polyphenol synthesis.

    PubMed

    Srinivasan, Aravind; Wu, Xiaoqiu; Lee, Moo-Yeal; Dordick, Jonathan S

    2003-03-01

    An enzyme-containing microfluidic biochip has been developed for the oxidative polymerization of phenols. The biochip consists of a simple T-junction with two feed reservoirs 20 mm apart and a microreaction channel 30 mm long. The channel is 15 microm deep and 200 microm wide at the center, giving a reaction volume of 90 nL. The biochip was fabricated using conventional photolithographic methods on a glass substrate etched using a HF-based solution. Fluid transport was enabled using electroosmotic flow. Soybean peroxidase was used as the phenol oxidizing catalyst, and in the presence of p-cresol and H(2)O(2), essentially complete conversion of the H(2)O(2) (the limiting substrate) occurred in the microchannel at a flow rate of ca. 290 nL/min. Thus, peroxidase was found to be intrinsically active even upon dramatic scale-down as achieved in microfluidic reactors. These results were extended to a series of phenols, thereby demonstrating that the microfluidic peroxidase reactor may have application in high-throughput screening of phenolic polymerization reactions for use in phenolic resin synthesis. Finally, rapid growth of poly(p-cresol) on the walls of the microreaction channel could be performed in the presence of higher H(2)O(2) concentrations. This finding suggests that solution-phase peroxidase catalysis can be used in the controlled deposition of polymers on the walls of microreactors. PMID:12514805

  18. Bioconjugation of antibodies to horseradish peroxidase (hrp)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The bioconjugation of an antibody to an enzymatic reporter such as horseradish peroxidase (HRP) affords an effective mechanism by which immunoassay detection of a target antigen can be achieved. The use of heterobifunctional cross—linkers to covalently link antibodies to HRP provides a simple and c...

  19. Enhanced Tolerance of Transgenic Potato Plants Over-Expressing Non-specific Lipid Transfer Protein-1 (StnsLTP1) against Multiple Abiotic Stresses.

    PubMed

    Gangadhar, Baniekal H; Sajeesh, Kappachery; Venkatesh, Jelli; Baskar, Venkidasamy; Abhinandan, Kumar; Yu, Jae W; Prasad, Ram; Mishra, Raghvendra K

    2016-01-01

    Abiotic stresses such as heat, drought, and salinity are major environmental constraints that limit potato (Solanum tuberosum L.) production worldwide. Previously, we found a potential thermo-tolerance gene, named StnsLTP1 from potato using yeast functional screening. Here, we report the functional characterization of StnsLTP1 and its role in multiple abiotic stresses in potato plants. Computational analysis of StnsLTP1 with other plant LTPs showed eight conserved cysteine residues, and four α-helices stabilized by four disulfide bridges. Expression analysis of StnsLTP1 gene showed differential expression under heat, water-deficit and salt stresses. Transgenic potato lines over-expressing StnsLTP1 gene displayed enhanced cell membrane integrity under stress conditions, as indicated by reduced membrane lipid per-oxidation, and hydrogen peroxide content relative to untransformed (UT) control plants. In addition, transgenic lines over-expressing StLTP1 also exhibited increased antioxidant enzyme activity with enhanced accumulation of ascorbates, and up-regulation of stress-related genes including StAPX, StCAT, StSOD, StHsfA3, StHSP70, and StsHSP20 compared with the UT plants. These results suggests that StnsLTP1 transgenic plants acquired improved tolerance to multiple abiotic stresses through enhanced activation of antioxidative defense mechanisms via cyclic scavenging of reactive oxygen species and regulated expression of stress-related genes. PMID:27597854

  20. Enhanced Tolerance of Transgenic Potato Plants Over-Expressing Non-specific Lipid Transfer Protein-1 (StnsLTP1) against Multiple Abiotic Stresses

    PubMed Central

    Gangadhar, Baniekal H.; Sajeesh, Kappachery; Venkatesh, Jelli; Baskar, Venkidasamy; Abhinandan, Kumar; Yu, Jae W.; Prasad, Ram; Mishra, Raghvendra K.

    2016-01-01

    Abiotic stresses such as heat, drought, and salinity are major environmental constraints that limit potato (Solanum tuberosum L.) production worldwide. Previously, we found a potential thermo-tolerance gene, named StnsLTP1 from potato using yeast functional screening. Here, we report the functional characterization of StnsLTP1 and its role in multiple abiotic stresses in potato plants. Computational analysis of StnsLTP1 with other plant LTPs showed eight conserved cysteine residues, and four α-helices stabilized by four disulfide bridges. Expression analysis of StnsLTP1 gene showed differential expression under heat, water-deficit and salt stresses. Transgenic potato lines over-expressing StnsLTP1 gene displayed enhanced cell membrane integrity under stress conditions, as indicated by reduced membrane lipid per-oxidation, and hydrogen peroxide content relative to untransformed (UT) control plants. In addition, transgenic lines over-expressing StLTP1 also exhibited increased antioxidant enzyme activity with enhanced accumulation of ascorbates, and up-regulation of stress-related genes including StAPX, StCAT, StSOD, StHsfA3, StHSP70, and StsHSP20 compared with the UT plants. These results suggests that StnsLTP1 transgenic plants acquired improved tolerance to multiple abiotic stresses through enhanced activation of antioxidative defense mechanisms via cyclic scavenging of reactive oxygen species and regulated expression of stress-related genes. PMID:27597854

  1. Identification and Properties of Insect Resistance-Associated Maize Anionic Peroxidases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous studies with transgenic plants have indicated a tobacco anionic peroxidase can confer enhanced resistance to a variety of insects when expressed in different plant species. Tissue that expresses high levels of this enzyme often browns rapidly when damaged. When introduced biolistically, m...

  2. Peroxidase gene discovery from the horseradish transcriptome

    PubMed Central

    2014-01-01

    Background Horseradish peroxidases (HRPs) from Armoracia rusticana have long been utilized as reporters in various diagnostic assays and histochemical stainings. Regardless of their increasing importance in the field of life sciences and suggested uses in medical applications, chemical synthesis and other industrial applications, the HRP isoenzymes, their substrate specificities and enzymatic properties are poorly characterized. Due to lacking sequence information of natural isoenzymes and the low levels of HRP expression in heterologous hosts, commercially available HRP is still extracted as a mixture of isoenzymes from the roots of A. rusticana. Results In this study, a normalized, size-selected A. rusticana transcriptome library was sequenced using 454 Titanium technology. The resulting reads were assembled into 14871 isotigs with an average length of 1133 bp. Sequence databases, ORF finding and ORF characterization were utilized to identify peroxidase genes from the 14871 isotigs generated by de novo assembly. The sequences were manually reviewed and verified with Sanger sequencing of PCR amplified genomic fragments, resulting in the discovery of 28 secretory peroxidases, 23 of them previously unknown. A total of 22 isoenzymes including allelic variants were successfully expressed in Pichia pastoris and showed peroxidase activity with at least one of the substrates tested, thus enabling their development into commercial pure isoenzymes. Conclusions This study demonstrates that transcriptome sequencing combined with sequence motif search is a powerful concept for the discovery and quick supply of new enzymes and isoenzymes from any plant or other eukaryotic organisms. Identification and manual verification of the sequences of 28 HRP isoenzymes do not only contribute a set of peroxidases for industrial, biological and biomedical applications, but also provide valuable information on the reliability of the approach in identifying and characterizing a large group

  3. Enhancing tolerance to short-chain alcohols by engineering the Escherichia coli AcrB efflux pump to secrete the non-native substrate n-butanol.

    PubMed

    Fisher, Michael A; Boyarskiy, Sergey; Yamada, Masaki R; Kong, Niwen; Bauer, Stefan; Tullman-Ercek, Danielle

    2014-01-17

    The microbial conversion of sugars to fuels is a promising technology, but the byproducts of biomass pretreatment processes and the fuels themselves are often toxic at industrially relevant levels. One promising solution to these problems is to engineer efflux pumps to secrete fuels and inhibitory chemicals from the cell, increasing microbial tolerance and enabling higher fuel titer. Toward that end, we used a directed evolution strategy to generate variants of the Escherichia coli AcrB efflux pump that act on the non-native substrate n-butanol, enhancing growth rates of E. coli in the presence of this biofuel by up to 25%. Furthermore, these variants confer improved tolerance to isobutanol and straight-chain alcohols up to n-heptanol. Single amino acid changes in AcrB responsible for this phenotype were identified. We have also shown that both the chemical and genetic inactivation of pump activity eliminate the tolerance conferred by AcrB pump variants, supporting our assertion that the variants secrete the non-native substrates. This strategy can be applied to create an array of efflux pumps that modulate the intracellular concentrations of small molecules of interest to microbial fuel and chemical production. PMID:23991711

  4. Increased lead and cadmium tolerance of Typha angustifolia from Huaihe River is associated with enhanced phytochelatin synthesis and improved antioxidative capacity.

    PubMed

    Liu, Yunlei; Chen, Jian; Lu, Shaonan; Yang, Libo; Qian, Jiazhong; Cao, Shuqing

    2016-11-01

    Heavy metal contamination of water is an increasing environmental problem worldwide, and the use of aquatic plants for phytoremediation of heavy metal pollution has become an important subject of research. One key to successful phytoremediation is the identification of plants that are efficient at sequestering heavy metals. In this study, we examined the growth and heavy metal accumulation of Typha angustifolia and compared growth characteristics and tolerance mechanisms in plants from the Huaihe and Chaohu Rivers irrigated with different concentrations of lead (Pb) and cadmium (Cd). T. angustifolia from Huaihe River showed enhanced tolerance and accumulation of Pb and Cd and had greater biomass and more vigorous growth than the ecotype from Chaohu River. In addition, higher phytochelatin (PC) content and significantly higher superoxide dismutase and catalase activities were detected in T. angustifolia from Huaihe River than in T. angustifolia from Chaohu River. These findings suggest that high Pb and Cd accumulation and tolerance in T. angustifolia from Chaohu River is associated with its higher PC synthesis and better antioxidative capacity, and that the Huaihe ecotype of T. angustifolia might also be an efficient species for phytoremediation of Pb and Cd in water contaminated by heavy metals. PMID:26959972

  5. A ginseng PgTIP1 gene whose protein biological activity related to Ser(128) residue confers faster growth and enhanced salt stress tolerance in Arabidopsis.

    PubMed

    Li, Jia; Cai, Weiming

    2015-05-01

    Water movement across cellular membranes is mostly regulated by aquaporins. A tonoplast intrinsic protein PgTIP1 from Panax ginseng has been found to play an important role in plant growth and development, and also in the response of plants to abiotic stress. However, the regulation of its function and activity remains unknown. To answer this question, mutated forms of PgTIP1 were made by replacing Ser(128) with Ala (named S128A) or Asp (named S128D), and also by replacing Thr(54) with Ala (named T54A) or Asp (named T54D). Then, wild type or mutated PgTIP1 was expressed in yeast and water transport was monitored in protoplasts. The substitution of Ser(128) abolished the water channel activity of PgTIP1, while the substitution of Thr(54) did not inhibit its activity. Moreover, the overexpression of PgTIP1 but not S128A or S128D in Arabidopsis significantly increased plant growth as determined by biomass production, it also had a beneficial effect on salt stress tolerance. Importantly, the overexpression of PgTIP1 led to the altered expression of stress-related genes, which made the plants more tolerant to salt stress. Our results demonstrated that PgTIP1 conferred faster growth and enhanced tolerance to salt in Arabidopsis, and that its biological activity related to Ser(128) residue. PMID:25804811

  6. Enhanced Gene Expression Rather than Natural Polymorphism in Coding Sequence of the OsbZIP23 Determines Drought Tolerance and Yield Improvement in Rice Genotypes

    PubMed Central

    Dey, Avishek; Samanta, Milan Kumar; Gayen, Srimonta; Sen, Soumitra K.; Maiti, Mrinal K.

    2016-01-01

    Drought is one of the major limiting factors for productivity of crops including rice (Oryza sativa L.). Understanding the role of allelic variations of key regulatory genes involved in stress-tolerance is essential for developing an effective strategy to combat drought. The bZIP transcription factors play a crucial role in abiotic-stress adaptation in plants via abscisic acid (ABA) signaling pathway. The present study aimed to search for allelic polymorphism in the OsbZIP23 gene across selected drought-tolerant and drought-sensitive rice genotypes, and to characterize the new allele through overexpression (OE) and gene-silencing (RNAi). Analyses of the coding DNA sequence (CDS) of the cloned OsbZIP23 gene revealed single nucleotide polymorphism at four places and a 15-nucleotide deletion at one place. The single-copy OsbZIP23 gene is expressed at relatively higher level in leaf tissues of drought-tolerant genotypes, and its abundance is more in reproductive stage. Cloning and sequence analyses of the OsbZIP23-promoter from drought-tolerant O. rufipogon and drought-sensitive IR20 cultivar showed variation in the number of stress-responsive cis-elements and a 35-nucleotide deletion at 5’-UTR in IR20. Analysis of the GFP reporter gene function revealed that the promoter activity of O. rufipogon is comparatively higher than that of IR20. The overexpression of any of the two polymorphic forms (1083 bp and 1068 bp CDS) of OsbZIP23 improved drought tolerance and yield-related traits significantly by retaining higher content of cellular water, soluble sugar and proline; and exhibited decrease in membrane lipid peroxidation in comparison to RNAi lines and non-transgenic plants. The OE lines showed higher expression of target genes-OsRab16B, OsRab21 and OsLEA3-1 and increased ABA sensitivity; indicating that OsbZIP23 is a positive transcriptional-regulator of the ABA-signaling pathway. Taken together, the present study concludes that the enhanced gene expression rather

  7. Enhanced Gene Expression Rather than Natural Polymorphism in Coding Sequence of the OsbZIP23 Determines Drought Tolerance and Yield Improvement in Rice Genotypes.

    PubMed

    Dey, Avishek; Samanta, Milan Kumar; Gayen, Srimonta; Sen, Soumitra K; Maiti, Mrinal K

    2016-01-01

    Drought is one of the major limiting factors for productivity of crops including rice (Oryza sativa L.). Understanding the role of allelic variations of key regulatory genes involved in stress-tolerance is essential for developing an effective strategy to combat drought. The bZIP transcription factors play a crucial role in abiotic-stress adaptation in plants via abscisic acid (ABA) signaling pathway. The present study aimed to search for allelic polymorphism in the OsbZIP23 gene across selected drought-tolerant and drought-sensitive rice genotypes, and to characterize the new allele through overexpression (OE) and gene-silencing (RNAi). Analyses of the coding DNA sequence (CDS) of the cloned OsbZIP23 gene revealed single nucleotide polymorphism at four places and a 15-nucleotide deletion at one place. The single-copy OsbZIP23 gene is expressed at relatively higher level in leaf tissues of drought-tolerant genotypes, and its abundance is more in reproductive stage. Cloning and sequence analyses of the OsbZIP23-promoter from drought-tolerant O. rufipogon and drought-sensitive IR20 cultivar showed variation in the number of stress-responsive cis-elements and a 35-nucleotide deletion at 5'-UTR in IR20. Analysis of the GFP reporter gene function revealed that the promoter activity of O. rufipogon is comparatively higher than that of IR20. The overexpression of any of the two polymorphic forms (1083 bp and 1068 bp CDS) of OsbZIP23 improved drought tolerance and yield-related traits significantly by retaining higher content of cellular water, soluble sugar and proline; and exhibited decrease in membrane lipid peroxidation in comparison to RNAi lines and non-transgenic plants. The OE lines showed higher expression of target genes-OsRab16B, OsRab21 and OsLEA3-1 and increased ABA sensitivity; indicating that OsbZIP23 is a positive transcriptional-regulator of the ABA-signaling pathway. Taken together, the present study concludes that the enhanced gene expression rather than

  8. Characteristics of estrogen-induced peroxidase in mouse uterine luminal fluid

    SciTech Connect

    Jellinck, P.H.; Newbold, R.R.; McLachlan, J.A. )

    1991-04-01

    Peroxidase activity in the uterine luminal fluid of mice treated with diethylstilbestrol was measured by the guaiacol assay and also by the formation of 3H2O from (2-3H)estradiol. In the radiometric assay, the generation of 3H2O and 3H-labeled water-soluble products was dependent on H2O2 (25 to 100 microM), with higher concentrations being inhibitory. Tyrosine or 2,4-dichlorophenol strongly enhanced the reaction catalyzed either by the luminal fluid peroxidase or the enzyme in the CaCl2 extract of the uterus, but decreased the formation of 3H2O from (2-3H)estradiol by lactoperoxidase in the presence of H2O2 (80 microM). NADPH, ascorbate, and cytochrome c inhibited both luminal fluid and uterine tissue peroxidase activity to the same extent, while superoxide dismutase showed a marginal activating effect. Lactoferrin, a major protein component of uterine luminal fluid, was shown not to contribute to its peroxidative activity, and such an effect by prostaglandin synthase was also ruled out. However, it was not possible to exclude eosinophil peroxidase, brought to the uterus after estrogen stimulation, as being the source of peroxidase activity in uterine luminal fluid.

  9. [Characterization of lignin and Mn peroxidases from Phanerochaete chrysosporium

    SciTech Connect

    Not Available

    1992-01-01

    Lignin peroxidases were investigated with respect to enzyme kinetics and NMR spectroscopy of the heme domain. MN peroxidases were studied with respect to the role of oxalate in enzyme activity, the NMR spectroscopy of the heme domain. Gene expression of both lignin and MN peroxidases were examined as well as expression of site-directed mutants aimed at scale up production of these enzymes.

  10. PEROXIDASE GENE POLYMORPHISM IN BUFFALOGRASS AND OTHER GRASSES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant peroxidases are a family of related proteins possessing highly conserved domains. Degenerate oligonucleotide primers based on these conserved domains can be used to amplify DNA sequences coding for peroxidases from plants with unsequenced genomes. Polymorphisms in peroxidase genes among buffa...

  11. Overexpression of ShDHN, a dehydrin gene from Solanum habrochaites enhances tolerance to multiple abiotic stresses in tomato.

    PubMed

    Liu, Hui; Yu, Chuying; Li, Hanxia; Ouyang, Bo; Wang, Taotao; Zhang, Junhong; Wang, Xin; Ye, Zhibiao

    2015-02-01

    Dehydrins (DHNs) play important roles in plant adaptation to abiotic stress. In this study, a cold-induced SK3-type DHN gene (ShDHN) isolated from wild tomato species Solanum habrochaites was characterized for its function in abiotic stress tolerance. ShDHN was constitutively expressed in root, leaf, stem, flower and fruit. ShDHN was continuously up-regulated during cold stress and showed higher expression level in the cold-tolerant S. habrochaites than in the susceptible S. lycopersicum. Moreover, ShDHN expression was also regulated by drought, salt, osmotic stress, and exogenous signaling molecules. Overexpression of ShDHN in cultivated tomato increased tolerance to cold and drought stresses and improved seedling growth under salt and osmotic stresses. Compared with the wild-type, the transgenic plants accumulated more proline, maintained higher enzymatic activities of superoxide dismutase and catalase, and suffered less membrane damage under cold and drought stresses. Moreover, the transgenic plants accumulated lower levels of H2O2 and O2(-) under cold stress, and had higher relative water contents and lower water loss rates under dehydration conditions. Furthermore, overexpression of ShDHN in tomato led to the up- or down-regulated expression of several genes involved in ROS scavenging and JA signaling pathway, including SOD1, GST, POD, LOX, PR1 and PR2. Taken together, these results indicate that ShDHN has pleiotropic effects on improving plant adaptation to abiotic stresses and that it possesses potential usefulness in genetic improvement of stress tolerance in tomato. PMID:25576005

  12. Mutation of OsGIGANTEA Leads to Enhanced Tolerance to Polyethylene Glycol-Generated Osmotic Stress in Rice.

    PubMed

    Li, Shuai; Yue, Wenhao; Wang, Min; Qiu, Wenmin; Zhou, Lian; Shou, Huixia

    2016-01-01

    Water deficit is one of the most important environmental stresses limiting plant growth and crop yield. While the identification of many key factors involved in the plant water deficit response has greatly increased our knowledge about the regulation system, the mechanisms underlying dehydration tolerance in plants are still not well understood. In our current study, we investigated the roles of the key flowering time regulator, OsGIGANTEA (OsGI), in the osmotic stress tolerance in rice. Results showed that mutation of OsGI conferred tolerance to osmotic stress generated by polyethylene glycol (PEG), increased proline and sucrose contents, and accelerated stomata movement. In addition, qRT-PCR and microarray analysis revealed that the transcript abundance of some osmotic stress response genes, such as OsDREB1E, OsAP37, OsAP59, OsLIP9, OsLEA3, OsRAB16A, and OsSalT, was significantly higher in osgi than in WT plants, suggesting that OsGI might be a negative regulator in the osmotic stress response in rice. PMID:27148296

  13. Ectopic expression of Arabidopsis thaliana Na+(K+)/H+ antiporter gene, AtNHX5, enhances soybean salt tolerance.

    PubMed

    Wu, X X; Li, J; Wu, X D; Liu, Q; Wang, Z K; Liu, S S; Li, S N; Ma, Y L; Sun, J; Zhao, L; Li, H Y; Li, D M; Li, W B; Su, A Y

    2016-01-01

    Drought and salt stresses are the two major factors influencing the yield and quality of crops worldwide. Na(+)(K(+))/H(+) antiporters (NHXs) are ubiquitous membrane proteins that play important roles in maintaining the cellular pH and Na(+)(K(+)) homeostasis. The model plant Arabidopsis potentially encodes six NHX genes, namely AtNHX1 to 6. In the present study, AtNHX5, a comparatively less well-studied NHX, was cloned and transferred into a soybean variety, Dongnong-50, via Agrobacterium-mediated cotyledonary node transformation to assess its role in improving salt tolerance of the transgenic plants. The transgenic soybean plants were tolerant to the presence of 300 mM NaCl whereas the non-transgenic plants were not. Furthermore, after NaCl treatment, the transgenic plants had a higher content of free proline but lower content of malondialdehyde compared to the non-transgenic plants. Our results revealed that that AtNHX5 possibly functioned by efficiently transporting Na(+) and K(+) ions from the roots to the leaves. Overall, the results obtained in this study suggest that soybean salt tolerance could be improved through the over expression of Arabidopsis AtNHX5. PMID:27323012

  14. Mutation of OsGIGANTEA Leads to Enhanced Tolerance to Polyethylene Glycol-Generated Osmotic Stress in Rice

    PubMed Central

    Li, Shuai; Yue, Wenhao; Wang, Min; Qiu, Wenmin; Zhou, Lian; Shou, Huixia

    2016-01-01

    Water deficit is one of the most important environmental stresses limiting plant growth and crop yield. While the identification of many key factors involved in the plant water deficit response has greatly increased our knowledge about the regulation system, the mechanisms underlying dehydration tolerance in plants are still not well understood. In our current study, we investigated the roles of the key flowering time regulator, OsGIGANTEA (OsGI), in the osmotic stress tolerance in rice. Results showed that mutation of OsGI conferred tolerance to osmotic stress generated by polyethylene glycol (PEG), increased proline and sucrose contents, and accelerated stomata movement. In addition, qRT-PCR and microarray analysis revealed that the transcript abundance of some osmotic stress response genes, such as OsDREB1E, OsAP37, OsAP59, OsLIP9, OsLEA3, OsRAB16A, and OsSalT, was significantly higher in osgi than in WT plants, suggesting that OsGI might be a negative regulator in the osmotic stress response in rice. PMID:27148296

  15. The SsDREB Transcription Factor from the Succulent Halophyte Suaeda salsa Enhances Abiotic Stress Tolerance in Transgenic Tobacco

    PubMed Central

    Zhang, Xu; Liu, Xiaoxue; Wu, Lei; Yu, Guihong; Wang, Xiue; Ma, Hongxiang

    2015-01-01

    Dehydration-responsive element-binding (DREB) transcription factor (TF) plays a key role for abiotic stress tolerance in plants. In this study, a novel cDNA encoding DREB transcription factor, designated SsDREB, was isolated from succulent halophyte Suaeda salsa. This protein was classified in the A-6 group of DREB subfamily based on multiple sequence alignments and phylogenetic characterization. Yeast one-hybrid assays showed that SsDREB protein specifically binds to the DRE sequence and could activate the expression of reporter genes in yeast, suggesting that the SsDREB protein was a CBF/DREB transcription factor. Real-time RT-PCR showed that SsDREB was significantly induced under salinity and drought stress. Overexpression of SsDREB cDNA in transgenic tobacco plants exhibited an improved salt and drought stress tolerance in comparison to the nontransformed controls. The transgenic plants revealed better growth, higher chlorophyll content, and net photosynthesis rate, as well as higher level of proline and soluble sugars. The semiquantitative PCR of transgenics showed higher expression of stress-responsive genes. These data suggest that the SsDREB transcription factor is involved in the regulation of salt stress tolerance in tobacco by the activation of different downstream gene expression. PMID:26504772

  16. The SsDREB Transcription Factor from the Succulent Halophyte Suaeda salsa Enhances Abiotic Stress Tolerance in Transgenic Tobacco.

    PubMed

    Zhang, Xu; Liu, Xiaoxue; Wu, Lei; Yu, Guihong; Wang, Xiue; Ma, Hongxiang

    2015-01-01

    Dehydration-responsive element-binding (DREB) transcription factor (TF) plays a key role for abiotic stress tolerance in plants. In this study, a novel cDNA encoding DREB transcription factor, designated SsDREB, was isolated from succulent halophyte Suaeda salsa. This protein was classified in the A-6 group of DREB subfamily based on multiple sequence alignments and phylogenetic characterization. Yeast one-hybrid assays showed that SsDREB protein specifically binds to the DRE sequence and could activate the expression of reporter genes in yeast, suggesting that the SsDREB protein was a CBF/DREB transcription factor. Real-time RT-PCR showed that SsDREB was significantly induced under salinity and drought stress. Overexpression of SsDREB cDNA in transgenic tobacco plants exhibited an improved salt and drought stress tolerance in comparison to the nontransformed controls. The transgenic plants revealed better growth, higher chlorophyll content, and net photosynthesis rate, as well as higher level of proline and soluble sugars. The semiquantitative PCR of transgenics showed higher expression of stress-responsive genes. These data suggest that the SsDREB transcription factor is involved in the regulation of salt stress tolerance in tobacco by the activation of different downstream gene expression. PMID:26504772

  17. Utilization of acetic acid-rich pyrolytic bio-oil by microalga Chlamydomonas reinhardtii: reducing bio-oil toxicity and enhancing algal toxicity tolerance.

    PubMed

    Liang, Yi; Zhao, Xuefei; Chi, Zhanyou; Rover, Marjorie; Johnston, Patrick; Brown, Robert; Jarboe, Laura; Wen, Zhiyou

    2013-04-01

    This work was to utilize acetic acid contained in bio-oil for growth and lipid production of the microalga Chlamydomonas reinhardtii. The acetic acid-rich bio-oil fraction derived from fast pyrolysis of softwood contained 26% (w/w) acetic acid, formic acid, methanol, furfural, acetol, and phenolics as identified compounds, and 13% (w/w) unidentified compounds. Among those identified compounds, phenolics were most inhibitory to algal growth, followed by furfural and acetol. To enhance the fermentability of the bio-oil fraction, activated carbon was used to reduce the toxicity of the bio-oil, while metabolic evolution was used to enhance the toxicity tolerance of the microalgae. Combining activated carbon treatment and using evolved algal strain resulted in significant algal growth improvement. The results collectively showed that fast pyrolysis-fermentation process was a viable approach for converting biomass into fuels and chemicals. PMID:23455221

  18. A maize calcium-dependent protein kinase gene, ZmCPK4, positively regulated abscisic acid signaling and enhanced drought stress tolerance in transgenic Arabidopsis.

    PubMed

    Jiang, Shanshan; Zhang, Dan; Wang, Li; Pan, Jiaowen; Liu, Yang; Kong, Xiangpei; Zhou, Yan; Li, Dequan

    2013-10-01

    Calcium-dependent protein kinases (CDPKs) play essential roles in calcium-mediated signal transductions in plant response to abiotic stress. Several members have been identified to be regulators for plants response to abscisic acid (ABA) signaling. Here, we isolated a subgroup I CDPK gene, ZmCPK4, from maize. Quantitative real time PCR (qRT-PCR) analysis revealed that the ZmCPK4 transcripts were induced by various stresses and signal molecules. Transient and stable expression of the ZmCPK4-GFP fusion proteins revealed ZmCPK4 localized to the membrane. Moreover, overexpression of ZmCPK4 in the transgenic Arabidopsis enhanced ABA sensitivity in seed germination, seedling growth and stomatal movement. The transgenic plants also enhanced drought stress tolerance. Taken together, the results suggest that ZmCPK4 might be involved in ABA-mediated regulation of stomatal closure in response to drought stress. PMID:23911729

  19. Enhancement of DNaseI Salt Tolerance by Mimicking the Domain Structure of DNase from an Extremely Halotolerant Bacterium Thioalkalivibrio sp. K90mix

    PubMed Central

    Alzbutas, Gediminas; Kaniusaite, Milda; Lagunavicius, Arunas

    2016-01-01

    In our previous work we showed that DNaseI-like protein from an extremely halotolerant bacterium Thioalkalivibrio sp. K90mix retained its activity at salt concentrations as high as 4 M NaCl and the key factor allowing this was the C-terminal DNA-binding domain, which comprised two HhH (helix-hairpin-helix) motifs. The further investigations revealed that this domain originated from proteins related to bacterial competence ComEA/ComE proteins. It is likely that in the course of evolution the DNA-binding domain from these proteins was fused to a metallo-β-lactamase superfamily domain. Very likely such domain organization having proteins subsequently “donated” the DNA-binding domain to bacterial DNases. In this study we have mimicked this evolutionary step by fusing bovine DNaseI and DNA-binding domains. We have created two fusions: one harboring the DNA-binding domain of DNaseI-like protein from Thioalkalivibrio sp. K90mix and the second one harboring the DNA-binding domain of bacterial competence protein ComEA from Bacillus subtilis. Both domains enhanced salt tolerance of DNaseI, albeit to different extent. Molecular modeling revealed the essential differences between their interaction with DNA shedding some light on the differences in salt tolerance. In this study we have enhanced salt tolerance of bovine DNaseI; thus, we successfully mimicked the Nature’s evolutionary engineering that created the extremely halotolerant bacterial DNase. We have demonstrated that the newly engineered DNaseI variants can be successfully used in applications where activity of the wild type bovine DNaseI is impeded by buffers used. PMID:26939122

  20. Constitutive expression of a salinity-induced wheat WRKY transcription factor enhances salinity and ionic stress tolerance in transgenic Arabidopsis thaliana

    SciTech Connect

    Qin, Yuxiang; Tian, Yanchen; Han, Lu; Yang, Xinchao

    2013-11-15

    Highlights: •A class II WRKY transcription factor, TaWRKY79 was isolated and characterized. •TaWRKY79 was induced by NaCl or abscisic acid. •843 bp regulatory segment was sufficient to respond to ABA or NaCl treatment. •TaWRKY79 enhanced salinity and ionic tolerance while reduced sensitivity to ABA. •TaWRKY79 increased salinity and ionic tolerance in an ABA-dependent pathway. -- Abstract: The isolation and characterization of TaWRKY79, a wheat class II WRKY transcription factor, is described. Its 1297 bp coding region includes a 987 bp long open reading frame. TaWRKY79 was induced by stressing seedlings with either NaCl or abscisic acid (ABA). When a fusion between an 843 bp segment upstream of the TaWRKY79 coding sequence and GUS was introduced into Arabidopsis thaliana, GUS staining indicated that this upstream segment captured the sequence(s) required to respond to ABA or NaCl treatment. When TaWRKY79 was constitutively expressed as a transgene in A. thaliana, the transgenic plants showed an improved capacity to extend their primary root in the presence of either 100 mM NaCl, 10 mM LiCl or 2 μM ABA. The inference was that TaWRKY79 enhanced the level of tolerance to both salinity and ionic stress, while reducing the level of sensitivity to ABA. The ABA-related genes ABA1, ABA2 ABI1 and ABI5 were all up-regulated in the TaWRKY79 transgenic plants, suggesting that the transcription factor operates in an ABA-dependent pathway.

  1. Enhancement of DNaseI Salt Tolerance by Mimicking the Domain Structure of DNase from an Extremely Halotolerant Bacterium Thioalkalivibrio sp. K90mix.

    PubMed

    Alzbutas, Gediminas; Kaniusaite, Milda; Lagunavicius, Arunas

    2016-01-01

    In our previous work we showed that DNaseI-like protein from an extremely halotolerant bacterium Thioalkalivibrio sp. K90mix retained its activity at salt concentrations as high as 4 M NaCl and the key factor allowing this was the C-terminal DNA-binding domain, which comprised two HhH (helix-hairpin-helix) motifs. The further investigations revealed that this domain originated from proteins related to bacterial competence ComEA/ComE proteins. It is likely that in the course of evolution the DNA-binding domain from these proteins was fused to a metallo-β-lactamase superfamily domain. Very likely such domain organization having proteins subsequently "donated" the DNA-binding domain to bacterial DNases. In this study we have mimicked this evolutionary step by fusing bovine DNaseI and DNA-binding domains. We have created two fusions: one harboring the DNA-binding domain of DNaseI-like protein from Thioalkalivibrio sp. K90mix and the second one harboring the DNA-binding domain of bacterial competence protein ComEA from Bacillus subtilis. Both domains enhanced salt tolerance of DNaseI, albeit to different extent. Molecular modeling revealed the essential differences between their interaction with DNA shedding some light on the differences in salt tolerance. In this study we have enhanced salt tolerance of bovine DNaseI; thus, we successfully mimicked the Nature's evolutionary engineering that created the extremely halotolerant bacterial DNase. We have demonstrated that the newly engineered DNaseI variants can be successfully used in applications where activity of the wild type bovine DNaseI is impeded by buffers used. PMID:26939122

  2. Drought-tolerance of wheat improved by rhizosphere bacteria from harsh environments: enhanced biomass production and reduced emissions of stress volatiles.

    PubMed

    Timmusk, Salme; Abd El-Daim, Islam A; Copolovici, Lucian; Tanilas, Triin; Kännaste, Astrid; Behers, Lawrence; Nevo, Eviatar; Seisenbaeva, Gulaim; Stenström, Elna; Niinemets, Ülo

    2014-01-01

    Water is the key resource limiting world agricultural production. Although an impressive number of research reports have been published on plant drought tolerance enhancement via genetic modifications during the last few years, progress has been slower than expected. We suggest a feasible alternative strategy by application of rhizospheric bacteria coevolved with plant roots in harsh environments over millions of years, and harboring adaptive traits improving plant fitness under biotic and abiotic stresses. We show the effect of bacterial priming on wheat drought stress tolerance enhancement, resulting in up to 78% greater plant biomass and five-fold higher survivorship under severe drought. We monitored emissions of seven stress-related volatiles from bacterially-primed drought-stressed wheat seedlings, and demonstrated that three of these volatiles are likely promising candidates for a rapid non-invasive technique to assess crop drought stress and its mitigation in early phases of stress development. We conclude that gauging stress by elicited volatiles provides an effectual platform for rapid screening of potent bacterial strains and that priming with isolates of rhizospheric bacteria from harsh environments is a promising, novel way to improve plant water use efficiency. These new advancements importantly contribute towards solving food security issues in changing climates. PMID:24811199

  3. The Mitochondrion-Located Protein OsB12D1 Enhances Flooding Tolerance during Seed Germination and Early Seedling Growth in Rice

    PubMed Central

    He, Dongli; Zhang, Hui; Yang, Pingfang

    2014-01-01

    B12D belongs to a function unknown subgroup of the Balem (Barley aleurone and embryo) proteins. In our previous work on rice seed germination, we identified a B12D-like protein encoded by LOC_Os7g41350 (named OsB12D1). OsB12D1 pertains to an ancient protein family with an amino acid sequence highly conserved from moss to angiosperms. Among the six OsB12Ds, OsB12D1 is one of the major transcripts and is primarily expressed in germinating seed and root. Bioinformatics analyses indicated that OsB12D1 is an anoxic or submergence resistance-related gene. RT-PCR results showed OsB12D1 is induced remarkably in the coleoptiles or roots by flooding during seed germination and early seedling growth. The OsB12D1-overexpressed rice seeds could protrude radicles in 8 cm deep water, further exhibiting significant flooding tolerance compared to the wild type. Moreover, this tolerance was not affected by the gibberellin biosynthesis inhibitor paclobutrazol. OsB12D1 was identified in the mitochondrion by subcellular localization analysis and possibly enhances electron transport through mediating Fe and oxygen availability under flooded conditions. This work indicated that OsB12D1 is a promising gene that can help to enhance rice seedling establishment in farming practices, especially for direct seeding. PMID:25089878

  4. Drought-Tolerance of Wheat Improved by Rhizosphere Bacteria from Harsh Environments: Enhanced Biomass Production and Reduced Emissions of Stress Volatiles

    PubMed Central

    Timmusk, Salme; Abd El-Daim, Islam A.; Copolovici, Lucian; Tanilas, Triin; Kännaste, Astrid; Behers, Lawrence; Nevo, Eviatar; Seisenbaeva, Gulaim; Stenström, Elna; Niinemets, Ülo

    2014-01-01

    Water is the key resource limiting world agricultural production. Although an impressive number of research reports have been published on plant drought tolerance enhancement via genetic modifications during the last few years, progress has been slower than expected. We suggest a feasible alternative strategy by application of rhizospheric bacteria coevolved with plant roots in harsh environments over millions of years, and harboring adaptive traits improving plant fitness under biotic and abiotic stresses. We show the effect of bacterial priming on wheat drought stress tolerance enhancement, resulting in up to 78% greater plant biomass and five-fold higher survivorship under severe drought. We monitored emissions of seven stress-related volatiles from bacterially-primed drought-stressed wheat seedlings, and demonstrated that three of these volatiles are likely promising candidates for a rapid non-invasive technique to assess crop drought stress and its mitigation in early phases of stress development. We conclude that gauging stress by elicited volatiles provides an effectual platform for rapid screening of potent bacterial strains and that priming with isolates of rhizospheric bacteria from harsh environments is a promising, novel way to improve plant water use efficiency. These new advancements importantly contribute towards solving food security issues in changing climates. PMID:24811199

  5. Overexpression of Rice NAC Gene SNAC1 Improves Drought and Salt Tolerance by Enhancing Root Development and Reducing Transpiration Rate in Transgenic Cotton

    PubMed Central

    Liu, Guanze; Li, Xuelin; Jin, Shuangxia; Liu, Xuyan; Zhu, Longfu; Nie, Yichun; Zhang, Xianlong

    2014-01-01

    The SNAC1 gene belongs to the stress-related NAC superfamily of transcription factors. It was identified from rice and overexpressed in cotton cultivar YZ1 by Agrobacterium tumefaciens-mediated transformation. SNAC1-overexpressing cotton plants showed more vigorous growth, especially in terms of root development, than the wild-type plants in the presence of 250 mM NaCl under hydroponic growth conditions. The content of proline was enhanced but the MDA content was decreased in the transgenic cotton seedlings under drought and salt treatments compared to the wild-type. Furthermore, SNAC1-overexpressing cotton plants also displayed significantly improved tolerance to both drought and salt stresses in the greenhouse. The performances of the SNAC1-overexpressing lines under drought and salt stress were significantly better than those of the wild-type in terms of the boll number. During the drought and salt treatments, the transpiration rate of transgenic plants significantly decreased in comparison to the wild-type, but the photosynthesis rate maintained the same at the flowering stage in the transgenic plants. These results suggested that overexpression of SNAC1 improve more tolerance to drought and salt in cotton through enhanced root development and reduced transpiration rates. PMID:24489802

  6. Co-expression of xerophyte Zygophyllum xanthoxylum ZxNHX and ZxVP1-1 confers enhanced salinity tolerance in chimeric sugar beet (Beta vulgaris L.).

    PubMed

    Wu, Guo-Qiang; Feng, Rui-Jun; Wang, Suo-Min; Wang, Chun-Mei; Bao, Ai-Ke; Wei, Li; Yuan, Hui-Jun

    2015-01-01

    Salinity is one of the major abiotic stresses that limit the growth and productivity of sugar beet (Beta vulgaris L.). To improve sugar beet's salinity tolerance, the ZxNHX and ZxVP1-1 genes encoding tonoplast Na(+)/H(+) antiporter and H(+)-PPase from xerophyte Zygophyllum xanthoxylum were co-expressed by Agrobacterium tumefaciens-mediated transformation. It is showed here that co-expression of ZxNHX and ZxVP1-1 confers enhanced salinity tolerance to the transformed sugar beet plants compared with the wild-type (WT) plants. The chimeric plants grew well in the presence of high salinity (400 mM NaCl), whereas WT plants displayed chlorosis and died within 8 days. Compared to WT plants, the chimeric plants co-expressing ZxNHX and ZxVP1-1 accumulated more proline, Na(+) and K(+) in their leaves and petioles when exposed to high salinity, which caused lower solute potential, retained more water and thus subjected to lesser cell membrane damage. Interestingly, the chimeric plants accumulated higher sucrose, glucose and fructose contents in their storage roots than WT plants in the absence or presence of high salinity. Our results suggested that co-expression of ZxNHX and ZxVP1-1 improved the osmoregulatory capacity in chimeric sugar beet through increased compartmentalization of ions into the vacuoles by enhancing the activity of proton pumps and thus mitigated Na(+)-toxicity for plants. PMID:26284097

  7. Ethylene positively regulates cold tolerance in grapevine by modulating the expression of ETHYLENE RESPONSE FACTOR 057

    PubMed Central

    Sun, Xiaoming; Zhao, Tingting; Gan, Shuheng; Ren, Xiaodie; Fang, Linchuan; Karungo, Sospeter Karanja; Wang, Yi; Chen, Liang; Li, Shaohua; Xin, Haiping

    2016-01-01

    Ethylene (ET) is a gaseous plant hormone that plays essential roles in biotic and abiotic stress responses in plants. However, the role of ET in cold tolerance varies in different species. This study revealed that low temperature promotes the release of ET in grapevine. The treatment of exogenous 1-aminocyclopropane-1-carboxylate increased the cold tolerance of grapevine. By contrast, the application of the ET biosynthesis inhibitor aminoethoxyvinylglycine reduced the cold tolerance of grapevine. This finding suggested that ET positively affected cold stress responses in grapevine. The expression of VaERF057, an ET signaling downstream gene, was strongly induced by low temperature. The overexpression of VaERF057 also enhanced the cold tolerance of Arabidopsis. Under cold treatment, malondialdehyde content was lower and superoxide dismutase, peroxidase, and catalase activities were higher in transgenic lines than in wild-type plants. RNA-Seq results showed that 32 stress-related genes, such as CBF1-3, were upregulated in VaERF057-overexpressing transgenic line. Yeast one-hybrid results further demonstrated that VaERF057 specifically binds to GCC-box and DRE motifs. Thus, VaERF057 may directly regulate the expression of its target stress-responsive genes by interacting with a GCC-box or a DRE element. Our work confirmed that ET positively regulates cold tolerance in grapevine by modulating the expression of VaERF057. PMID:27039848

  8. Ethylene positively regulates cold tolerance in grapevine by modulating the expression of ETHYLENE RESPONSE FACTOR 057.

    PubMed

    Sun, Xiaoming; Zhao, Tingting; Gan, Shuheng; Ren, Xiaodie; Fang, Linchuan; Karungo, Sospeter Karanja; Wang, Yi; Chen, Liang; Li, Shaohua; Xin, Haiping

    2016-01-01

    Ethylene (ET) is a gaseous plant hormone that plays essential roles in biotic and abiotic stress responses in plants. However, the role of ET in cold tolerance varies in different species. This study revealed that low temperature promotes the release of ET in grapevine. The treatment of exogenous 1-aminocyclopropane-1-carboxylate increased the cold tolerance of grapevine. By contrast, the application of the ET biosynthesis inhibitor aminoethoxyvinylglycine reduced the cold tolerance of grapevine. This finding suggested that ET positively affected cold stress responses in grapevine. The expression of VaERF057, an ET signaling downstream gene, was strongly induced by low temperature. The overexpression of VaERF057 also enhanced the cold tolerance of Arabidopsis. Under cold treatment, malondialdehyde content was lower and superoxide dismutase, peroxidase, and catalase activities were higher in transgenic lines than in wild-type plants. RNA-Seq results showed that 32 stress-related genes, such as CBF1-3, were upregulated in VaERF057-overexpressing transgenic line. Yeast one-hybrid results further demonstrated that VaERF057 specifically binds to GCC-box and DRE motifs. Thus, VaERF057 may directly regulate the expression of its target stress-responsive genes by interacting with a GCC-box or a DRE element. Our work confirmed that ET positively regulates cold tolerance in grapevine by modulating the expression of VaERF057. PMID:27039848

  9. The Involvement of Wheat F-Box Protein Gene TaFBA1 in the Oxidative Stress Tolerance of Plants

    PubMed Central

    Zhou, Shu-Mei; Kong, Xiang-Zhu; Kang, Han-Han; Sun, Xiu-Dong; Wang, Wei

    2015-01-01

    As one of the largest gene families, F-box domain proteins have been found to play important roles in abiotic stress responses via the ubiquitin pathway. TaFBA1 encodes a homologous F-box protein contained in E3 ubiquitin ligases. In our previous study, we found that the overexpression of TaFBA1 enhanced drought tolerance in transgenic plants. To investigate the mechanisms involved, in this study, we investigated the tolerance of the transgenic plants to oxidative stress. Methyl viologen was used to induce oxidative stress conditions. Real-time PCR and western blot analysis revealed that TaFBA1 expression was up-regulated by oxidative stress treatments. Under oxidative stress conditions, the transgenic tobacco plants showed a higher germination rate, higher root length and less growth inhibition than wild type (WT). The enhanced oxidative stress tolerance of the transgenic plants was also indicated by lower reactive oxygen species (ROS) accumulation, malondialdehyde (MDA) content and cell membrane damage under oxidative stress compared with WT. Higher activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD), were observed in the transgenic plants than those in WT, which may be related to the upregulated expression of some antioxidant genes via the overexpression of TaFBA1. In others, some stress responsive elements were found in the promoter region of TaFBA1, and TaFBA1 was located in the nucleus, cytoplasm and plasma membrane. These results suggest that TaFBA1 plays an important role in the oxidative stress tolerance of plants. This is important for understanding the functions of F-box proteins in plants’ tolerance to multiple stress conditions. PMID:25906259

  10. Abscisic acid enhances tolerance of wheat seedlings to drought and regulates transcript levels of genes encoding ascorbate-glutathione biosynthesis.

    PubMed

    Wei, Liting; Wang, Lina; Yang, Yang; Wang, Pengfei; Guo, Tiancai; Kang, Guozhang

    2015-01-01

    Glutathione (GSH) and ascorbate (ASA) are associated with the abscisic acid (ABA)-induced abiotic tolerance in higher plant, however, its molecular mechanism remains obscure. In this study, exogenous application (10 μM) of ABA significantly increased the tolerance of seedlings of common wheat (Triticum aestivum L.) suffering from 5 days of 15% polyethylene glycol (PEG)-stimulated drought stress, as demonstrated by increased shoot lengths and shoot and root dry weights, while showing decreased content of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Under drought stress conditions, ABA markedly increased content of GSH and ASA in both leaves and roots of ABA-treated plants. Temporal and spatial expression patterns of eight genes encoding ASA and GSH synthesis-related enzymes were measured using quantitative real-time reverse transcription polymerase chain reaction (qPCR). The results showed that ABA temporally regulated the transcript levels of genes encoding ASA-GSH cycle enzymes. Moreover, these genes exhibited differential expression patterns between the root and leaf organs of ABA-treated wheat seedlings during drought stress. These results implied that exogenous ABA increased the levels of GSH and ASA in drought-stressed wheat seedlings in time- and organ-specific manners. Moreover, the transcriptional profiles of ASA-GSH synthesis-related enzyme genes in the leaf tissue were compared between ABA- and salicylic acid (SA)-treated wheat seedlings under PEG-stimulated drought stress, suggesting that they increased the content of ASA and GSH by differentially regulating expression levels of ASA-GSH synthesis enzyme genes. Our results increase our understanding of the molecular mechanism of ABA-induced drought tolerance in higher plants. PMID:26175737

  11. Heterologous Expression of Wheat VERNALIZATION 2 (TaVRN2) Gene in Arabidopsis Delays Flowering and Enhances Freezing Tolerance

    PubMed Central

    Diallo, Amadou; Kane, Ndjido; Agharbaoui, Zahra; Badawi, Mohamed; Sarhan, Fathey

    2010-01-01

    The vernalization gene 2 (VRN2), is a major flowering repressor in temperate cereals that is regulated by low temperature and photoperiod. Here we show that the gene from Triticum aestivum (TaVRN2) is also regulated by salt, heat shock, dehydration, wounding and abscissic acid. Promoter analysis indicates that TaVRN2 regulatory region possesses all the specific responsive elements to these stresses. This suggests pleiotropic effects of TaVRN2 in wheat development and adaptability to the environment. To test if TaVRN2 can act as a flowering repressor in species different from the temperate cereals, the gene was ectopically expressed in the model plant Arabidopsis. Transgenic plants showed no alteration in morphology, but their flowering time was significantly delayed compared to controls plants, indicating that TaVRN2, although having no ortholog in Brassicaceae, can act as a flowering repressor in these species. To identify the possible mechanism by which TaVRN2 gene delays flowering in Arabidopsis, the expression level of several genes involved in flowering time regulation was determined. The analysis indicates that the late flowering of the 35S::TaVRN2 plants was associated with a complex pattern of expression of the major flowering control genes, FCA, FLC, FT, FVE and SOC1. This suggests that heterologous expression of TaVRN2 in Arabidopsis can delay flowering by modulating several floral inductive pathways. Furthermore, transgenic plants showed higher freezing tolerance, likely due to the accumulation of CBF2, CBF3 and the COR genes. Overall, our data suggests that TaVRN2 gene could modulate a common regulator of the two interacting pathways that regulate flowering time and the induction of cold tolerance. The results also demonstrate that TaVRN2 could be used to manipulate flowering time and improve cold tolerance in other species. PMID:20084169

  12. Abscisic acid enhances tolerance of wheat seedlings to drought and regulates transcript levels of genes encoding ascorbate-glutathione biosynthesis

    PubMed Central

    Wei, Liting; Wang, Lina; Yang, Yang; Wang, Pengfei; Guo, Tiancai; Kang, Guozhang

    2015-01-01

    Glutathione (GSH) and ascorbate (ASA) are associated with the abscisic acid (ABA)-induced abiotic tolerance in higher plant, however, its molecular mechanism remains obscure. In this study, exogenous application (10 μM) of ABA significantly increased the tolerance of seedlings of common wheat (Triticum aestivum L.) suffering from 5 days of 15% polyethylene glycol (PEG)-stimulated drought stress, as demonstrated by increased shoot lengths and shoot and root dry weights, while showing decreased content of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Under drought stress conditions, ABA markedly increased content of GSH and ASA in both leaves and roots of ABA-treated plants. Temporal and spatial expression patterns of eight genes encoding ASA and GSH synthesis-related enzymes were measured using quantitative real-time reverse transcription polymerase chain reaction (qPCR). The results showed that ABA temporally regulated the transcript levels of genes encoding ASA-GSH cycle enzymes. Moreover, these genes exhibited differential expression patterns between the root and leaf organs of ABA-treated wheat seedlings during drought stress. These results implied that exogenous ABA increased the levels of GSH and ASA in drought-stressed wheat seedlings in time- and organ-specific manners. Moreover, the transcriptional profiles of ASA-GSH synthesis-related enzyme genes in the leaf tissue were compared between ABA- and salicylic acid (SA)-treated wheat seedlings under PEG-stimulated drought stress, suggesting that they increased the content of ASA and GSH by differentially regulating expression levels of ASA-GSH synthesis enzyme genes. Our results increase our understanding of the molecular mechanism of ABA-induced drought tolerance in higher plants. PMID:26175737

  13. Ectopic Expression of GsPPCK3 and SCMRP in Medicago sativa Enhances Plant Alkaline Stress Tolerance and Methionine Content

    PubMed Central

    Zhao, Yang; Zhao, Chaoyue; DuanMu, Huizi; Yu, Yang; Ji, Wei; Zhu, Yanming

    2014-01-01

    So far, it has been suggested that phosphoenolpyruvate carboxylases (PEPCs) and PEPC kinases (PPCKs) fulfill several important non-photosynthetic functions. However, the biological functions of soybean PPCKs, especially in alkali stress response, are not yet well known. In previous studies, we constructed a Glycine soja transcriptional profile, and identified three PPCK genes (GsPPCK1, GsPPCK2 and GsPPCK3) as potential alkali stress responsive genes. In this study, we confirmed the induced expression of GsPPCK3 under alkali stress and investigated its tissue expression specificity by using quantitative real-time PCR analysis. Then we ectopically expressed GsPPCK3 in Medicago sativa and found that GsPPCK3 overexpression improved plant alkali tolerance, as evidenced by lower levels of relative ion leakage and MDA content and higher levels of chlorophyll content and root activity. In this respect, we further co-transformed the GsPPCK3 and SCMRP genes into alfalfa, and demonstrated the increased alkali tolerance of GsPPCK3-SCMRP transgenic lines. Further investigation revealed that GsPPCK3-SCMRP co-overexpression promoted the PEPC activity, net photosynthetic rate and citric acid content of transgenic alfalfa under alkali stress. Moreover, we also observed the up-regulated expression of PEPC, CS (citrate synthase), H+-ATPase and NADP-ME genes in GsPPCK3-SCMRP transgenic alfalfa under alkali stress. As expected, we demonstrated that GsPPCK3-SCMRP transgenic lines displayed higher methionine content than wild type alfalfa. Taken together, results presented in this study supported the positive role of GsPPCK3 in plant response to alkali stress, and provided an effective way to simultaneously improve plant alkaline tolerance and methionine content, at least in legume crops. PMID:24586886

  14. Roles of Lignin Peroxidase and Manganese Peroxidase from Phanerochaete chrysosporium in the Decolorization of Olive Mill Wastewaters

    PubMed Central

    Sayadi, S.; Ellouz, R.

    1995-01-01

    The relative contributions of lignin peroxidase (LiP) and manganese peroxidase (MnP) to the decolorization of olive mill wastewaters (OMW) by Phanerochaete chrysosporium were investigated. A relatively low level (25%) of OMW decolorization was found with P. chrysosporium which was grown in a medium with a high Mn(II) concentration and in which a high level of MnP (0.65 (mu)M) was produced. In contrast, a high degree of OMW decolorization (more than 70%) was observed with P. chrysosporium which was grown in a medium with a low Mn(II) concentration but which resulted in a high level of LiP activity (0.3 (mu)M). In this culture medium, increasing the Mn(II) concentration resulted in decreased levels of OMW decolorization and LiP activity. Decolorization by reconstituted cultures of P. chrysosporium was found to be more enhanced by the addition of isolated LiP than by the addition of isolated MnP. The highest OMW decolorization levels were obtained at low initial chemical oxygen demands combined with high levels of extracellular LiP. These data, plus the positive effect of veratryl alcohol on OMW decolorization and LiP activity, indicate that culture conditions which yield high levels of LiP activity lead to high levels of OMW decolorization. PMID:16534959

  15. NADH peroxidase: kinetic mechanism and nucleotide specificity

    SciTech Connect

    Stoll, V.S.; Blanchard, J.S.

    1987-05-01

    NADH peroxidase is a flavoprotein reductase isolated from Streptococcus faecalis which catalyzes the pyridine nucleotide dependent reduction of hydrogen peroxide to water. Initial velocity, product and dead-end inhibition studies have been performed and all support a ping-pong kinetic mechanism. Further support for the ping-pong nature of the kinetic mechanism are the hydrogen peroxide independent transhydrogenase activity of the enzyme, measured either with thio-NAD or with radiolabeled NAD (isotope exchange studies). Kinetic parameters will be presented for a number of reduced pyridine nucleotide analogs. Analogs which have been modified in the adenine ring exhibit much higher K/sub m/'s relative to their adenine analogs. NADH peroxidase catalyzes the stereo-specific removal of the 4S hydrogen of NADH and primary deuterium kinetic isotope effects have been determined for a number of these substrates with 4S-deuterated molecules. There is a strong correlation between their steady-state K/sub m/ and /sup D/V/K. Small values for /sup D/V are interpreted as supporting rate-limitation in the oxidative half-reaction. These data will be discussed in terms of a kinetic and chemical mechanism proposed for NADH peroxidase.

  16. Cytochrome bd Displays Significant Quinol Peroxidase Activity

    PubMed Central

    Al-Attar, Sinan; Yu, Yuanjie; Pinkse, Martijn; Hoeser, Jo; Friedrich, Thorsten; Bald, Dirk; de Vries, Simon

    2016-01-01

    Cytochrome bd is a prokaryotic terminal oxidase that catalyses the electrogenic reduction of oxygen to water using ubiquinol as electron donor. Cytochrome bd is a tri-haem integral membrane enzyme carrying a low-spin haem b558, and two high-spin haems: b595 and d. Here we show that besides its oxidase activity, cytochrome bd from Escherichia coli is a genuine quinol peroxidase (QPO) that reduces hydrogen peroxide to water. The highly active and pure enzyme preparation used in this study did not display the catalase activity recently reported for E. coli cytochrome bd. To our knowledge, cytochrome bd is the first membrane-bound quinol peroxidase detected in E. coli. The observation that cytochrome bd is a quinol peroxidase, can provide a biochemical basis for its role in detoxification of hydrogen peroxide and may explain the frequent findings reported in the literature that indicate increased sensitivity to hydrogen peroxide and decreased virulence in mutants that lack the enzyme. PMID:27279363

  17. Redox thermodynamics of lactoperoxidase and eosinophil peroxidase.

    PubMed

    Battistuzzi, Gianantonio; Bellei, Marzia; Vlasits, Jutta; Banerjee, Srijib; Furtmüller, Paul G; Sola, Marco; Obinger, Christian

    2010-02-01

    Eosinophil peroxidase (EPO) and lactoperoxidase (LPO) are important constituents of the innate immune system of mammals. These heme enzymes belong to the peroxidase-cyclooxygenase superfamily and catalyze the oxidation of thiocyanate, bromide and nitrite to hypothiocyanate, hypobromous acid and nitrogen dioxide that are toxic for invading pathogens. In order to gain a better understanding of the observed differences in substrate specificity and oxidation capacity in relation to heme and protein structure, a comprehensive spectro-electrochemical investigation was performed. The reduction potential (E degrees ') of the Fe(III)/Fe(II) couple of EPO and LPO was determined to be -126mV and -176mV, respectively (25 degrees C, pH 7.0). Variable temperature experiments show that EPO and LPO feature different reduction thermodynamics. In particular, reduction of ferric EPO is enthalpically and entropically disfavored, whereas in LPO the entropic term, which selectively stabilizes the oxidized form, prevails on the enthalpic term that favors reduction of Fe(III). The data are discussed with respect to the architecture of the heme cavity and the substrate channel. Comparison with published data for myeloperoxidase demonstrates the effect of heme to protein linkages and heme distortion on the redox chemistry of mammalian peroxidases and in consequence on the enzymatic properties of these physiologically important oxidoreductases. PMID:19944669

  18. Further characterization of human eosinophil peroxidase.

    PubMed Central

    Olsen, R L; Syse, K; Little, C; Christensen, T B

    1985-01-01

    The large and the small subunits (Mr 50 000 and 10 500 respectively) of human eosinophil peroxidase were isolated by gel filtration under reducing conditions. The subunits were very strongly associated but not apparently cross-linked by disulphide bridges. During storage, the large subunit tended to form aggregates, which required reduction to dissociate them. Amino acid analysis of the performic acid-treated large subunit showed the presence of 19 cysteic acid residues. The small subunit of eosinophil peroxidase had the same Mr value as the small subunit of myeloperoxidase. However, although these subunits have very similar amino acid compositions, they showed different patterns of peptide fragmentation after CNBr treatment. The carbohydrate of eosinophil peroxidase seemed associated exclusively with the large subunit and comprised mannose (4.5%, w/w) and N-acetylglucosamine (0.8%, w/w). The far-u.v.c.d. spectrum of the enzyme indicated the presence of relatively little ordered secondary structure. Images Fig. 3. PMID:4052025

  19. Overexpression of Iris. lactea var. chinensis metallothionein llMT2a enhances cadmium tolerance in Arabidopsis thaliana.

    PubMed

    Gu, Chun-Sun; Liu, Liang-qin; Zhao, Yan-Hai; Deng, Yan-ming; Zhu, Xu-dong; Huang, Su-Zhen

    2014-07-01

    Metallothioneins (MTs) are cysteine-rich, low molecular weight, heavy metal-binding protein molecules. Here, a full-length cDNA homologue of MT2a (type 2 metallothionein) was isolated from the cadmium-tolerant species Iris. lactea var. chinensis (I. lactea var. chinensis). Expression of IlMT2a in I. lactea var. chinensis roots and leaves was up-regulated in response to cadmium stress. When the gene was constitutively expressed in Arabidopsis thaliana (A. thaliana), root length of transgenic lines was longer than that of wild-type under 50μM or 100μM cadmium stress. However, there was no difference of cadmium absorption between wild-type and trangenic lines. Histochemical staining by 3,3-diaminobenzidine (DAB) and nitroblue tetrazoliu (NBT) clearly demonstrated that transgenic lines accumulated remarkably less H2O2 and O2(-) than wild-type. Together, IlMT2a may be a promising gene for the cadmium tolerance improvement. PMID:24780229

  20. Enhanced xylose fermentation and hydrolysate inhibitor tolerance of Scheffersomyces shehatae for efficient ethanol production from non-detoxified lignocellulosic hydrolysate.

    PubMed

    Senatham, Srisuda; Chamduang, Thada; Kaewchingduang, Yotin; Thammasittirong, Anon; Srisodsuk, Malee; Elliston, Adam; Roberts, Ian N; Waldron, Keith W; Thammasittirong, Sutticha Na-Ranong

    2016-01-01

    Effective conversion of xylose into ethanol is important for lignocellulosic ethanol production. In the present study, UV-C mutagenesis was used to improve the efficiency of xylose fermentation. The mutated Scheffersomyces shehatae strain TTC79 fermented glucose as efficiently and xylose more efficiently, producing a higher ethanol concentration than the wild-type. A maximum ethanol concentration of 29.04 g/L was produced from 71.31 g/L xylose, which was 58.95 % higher than that of the wild-type. This mutant also displayed significantly improved hydrolysate inhibitors tolerance and increased ethanol production from non-detoxified lignocellulosic hydrolysates. The ethanol yield, productivity and theoretical yield by TTC79 from sugarcane bagasse hydrolysate were 0.46 g/g, 0.20 g/L/h and 90.61 %, respectively, while the corresponding values for the wild-type were 0.20 g/g, 0.04 g/L/h and 39.20 %, respectively. These results demonstrate that S. shehatae TTC79 is a useful non-recombinant strain, combining efficient xylose consumption and high inhibitor tolerance, with potential for application in ethanol production from lignocellulose hydrolysates. PMID:27462488

  1. In planta transformation of sorghum (Sorghum bicolor (L.) Moench) using TPS1 gene for enhancing tolerance to abiotic stresses.

    PubMed

    Yellisetty, Varalaxmi; Reddy, L A; Mandapaka, Maheswari

    2015-09-01

    An in planta transformation protocol for sorghum (Sorghum bicolor (L.) Moench) using shoot apical meristem of germinating seedlings is reported in this study. Agrobacterium tumefaciens strain, LBA4404 with pCAMBIA1303 vector and construct pCAMBIA1303TPS1 were individually used for transformation. Since, the transgene is integrated into the cells of already differentiated tissues, the T 0 plants were chimeric and stable integration was observed in T1 generation. β-Glucuronidase (GUS) expression in the seedlings and spikelets of emerging cob was the first indication of transformability in T0 generation which was further confirmed by PCR analysis using hpt and TPS1 gene-specific primers. Screening on 25 mg/L hygromycin combined with PCR analysis was used for selection of transformants in the T1 generation. Transformation efficiencies ranged between 34-38% and 26-34% using pCAMBIA1303 vector and construct pCAMBIA1303TPS1, respectively. Molecular characterization of the T2 transgenics using PCR, RT-PCR and Southern blot analyses further revealed the integration, expression and inheritance of the transgene. These results indicate the feasibility of the method to generate transgenics with pCAM-BIA1303 vector and construct pCAMBIA1303TPS1. The abiotic stress tolerance of TPS1 transgenics developed in the present study was evident by the ability of the transformants to tolerate 200 mM NaCl as well as higher root growth and biomass. PMID:26440081

  2. Specificity of an HPETE peroxidase from rat PMN

    SciTech Connect

    Skoog, M.T.; Nichols, J.S.; Harrison, B.L.; Wiseman, J.S.

    1988-09-01

    The 15,000xg supernatant of sonicated rat PMN contains 5-lipoxygenase that converts arachidonic acid to 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and leukotriene A4 and an HPETE peroxidase that catalyzes reduction of the 5-HPETE. The specificity of this HPETE peroxidase for peroxides, reducing agents, and inhibitors has been characterized to distinguish this enzyme from other peroxidase activities. In addition to 5-HPETE, the HPETE peroxidase will catalyze reduction of 15-hydroperoxyeicosatetraenoic acid, 13-hydroperoxyoctadecadienoic acid, and 15-hydroperoxy-8,11,13-eicosatrienoic acid, but not cumene or t-butylhydroperoxides. The HPETE peroxidase accepted 5 of 11 thiols tested as reducing agents. However, glutathione is greater than 15 times more effective than any other thiol tested. Other reducing agents, ascorbate, NADH, NADPH, phenol, p-cresol, and homovanillic acid, were not accepted by HPETE peroxidase. This enzyme is not inhibited by 10 mM KCN, 2 mM aspirin, 2 mM salicylic acid, or 0.5 mM indomethacin. When 5-(14C)HPETE is generated from (14C)arachidonic acid in the presence of unlabeled 5-HPETE and the HPETE peroxidase, the 5-(14C)HETE produced is of much lower specific activity than the (14C)arachidonic acid. This indicates that the 5-(14C)HPETE leaves the active site of 5-lipoxygenase and mixes with the unlabeled 5-HPETE in solution prior to reduction and is a kinetic demonstration that 5-lipoxygenase has no peroxidase activity. Specificity for peroxides, reducing agents, and inhibitors differentiates HPETE peroxidase from glutathione peroxidase, phospholipid-hydroperoxide glutathione peroxidase, a 12-HPETE peroxidase, and heme peroxidases. The HPETE peroxidase could be a glutathione S-transferase selective for fatty acid hydroperoxides.

  3. TaSnRK2.4, an SNF1-type serine/threonine protein kinase of wheat (Triticum aestivum L.), confers enhanced multistress tolerance in Arabidopsis.

    PubMed

    Mao, Xinguo; Zhang, Hongying; Tian, Shanjun; Chang, Xiaoping; Jing, Ruilian

    2010-03-01

    Osmotic stresses such as drought, salinity, and cold are major environmental factors that limit agricultural productivity worldwide. Protein phosphorylation/dephosphorylation are major signalling events induced by osmotic stress in higher plants. Sucrose non-fermenting 1-related protein kinase2 family members play essential roles in response to hyperosmotic stresses in Arabidopsis, rice, and maize. In this study, the function of TaSnRK2.4 in drought, salt, and freezing stresses in Arabidopsis was characterized. A translational fusion protein of TaSnRK2.4 with green fluorescent protein showed subcellular localization in the cell membrane, cytoplasm, and nucleus. To examine the role of TaSnRK2.4 under various environmental stresses, transgenic Arabidopsis plants overexpressing wheat TaSnRK2.4 under control of the cauliflower mosaic virus 35S promoter were generated. Overexpression of TaSnRK2.4 resulted in delayed seedling establishment, longer primary roots, and higher yield under normal growing conditions. Transgenic Arabidopsis overexpressing TaSnRK2.4 had enhanced tolerance to drought, salt, and freezing stresses, which were simultaneously supported by physiological results, including decreased rate of water loss, enhanced higher relative water content, strengthened cell membrane stability, improved photosynthesis potential, and significantly increased osmotic potential. The results show that TaSnRK2.4 is involved in the regulation of enhanced osmotic potential, growth, and development under both normal and stress conditions, and imply that TaSnRK2.4 is a multifunctional regulatory factor in Arabidopsis. Since the overexpression of TaSnRK2.4 can significantly strengthen tolerance to drought, salt, and freezing stresses and does not retard the growth of transgenic Arabidopsis plants under well-watered conditions, TaSnRK2.4 could be utilized in transgenic breeding to improve abiotic stresses in crops. PMID:20022921

  4. Constitutive Expression of a miR319 Gene Alters Plant Development and Enhances Salt and Drought Tolerance in Transgenic Creeping Bentgrass1[W][OA

    PubMed Central

    Zhou, Man; Li, Dayong; Li, Zhigang; Hu, Qian; Yang, Chunhua; Zhu, Lihuang; Luo, Hong

    2013-01-01

    MicroRNA319 (miR319) is one of the first characterized and conserved microRNA families in plants and has been demonstrated to target TCP (for TEOSINTE BRANCHED/CYCLOIDEA/PROLIFERATING CELL FACTORS [PCF]) genes encoding plant-specific transcription factors. MiR319 expression is regulated by environmental stimuli, suggesting its involvement in plant stress response, although experimental evidence is lacking and the underlying mechanism remains elusive. This study investigates the role that miR319 plays in the plant response to abiotic stress using transgenic creeping bentgrass (Agrostis stolonifera) overexpressing a rice (Oryza sativa) miR319 gene, Osa-miR319a. We found that transgenic plants overexpressing Osa-miR319a displayed morphological changes and exhibited enhanced drought and salt tolerance associated with increased leaf wax content and water retention but reduced sodium uptake. Gene expression analysis indicated that at least four putative miR319 target genes, AsPCF5, AsPCF6, AsPCF8, and AsTCP14, and a homolog of the rice NAC domain gene AsNAC60 were down-regulated in transgenic plants. Our results demonstrate that miR319 controls plant responses to drought and salinity stress. The enhanced abiotic stress tolerance in transgenic plants is related to significant down-regulation of miR319 target genes, implying their potential for use in the development of novel molecular strategies to genetically engineer crop species for enhanced resistance to environmental stress. PMID:23292790

  5. Constitutive expression of a miR319 gene alters plant development and enhances salt and drought tolerance in transgenic creeping bentgrass.

    PubMed

    Zhou, Man; Li, Dayong; Li, Zhigang; Hu, Qian; Yang, Chunhua; Zhu, Lihuang; Luo, Hong

    2013-03-01

    MicroRNA319 (miR319) is one of the first characterized and conserved microRNA families in plants and has been demonstrated to target TCP (for TEOSINTE BRANCHED/CYCLOIDEA/PROLIFERATING CELL FACTORS [PCF]) genes encoding plant-specific transcription factors. MiR319 expression is regulated by environmental stimuli, suggesting its involvement in plant stress response, although experimental evidence is lacking and the underlying mechanism remains elusive. This study investigates the role that miR319 plays in the plant response to abiotic stress using transgenic creeping bentgrass (Agrostis stolonifera) overexpressing a rice (Oryza sativa) miR319 gene, Osa-miR319a. We found that transgenic plants overexpressing Osa-miR319a displayed morphological changes and exhibited enhanced drought and salt tolerance associated with increased leaf wax content and water retention but reduced sodium uptake. Gene expression analysis indicated that at least four putative miR319 target genes, AsPCF5, AsPCF6, AsPCF8, and AsTCP14, and a homolog of the rice NAC domain gene AsNAC60 were down-regulated in transgenic plants. Our results demonstrate that miR319 controls plant responses to drought and salinity stress. The enhanced abiotic stress tolerance in transgenic plants is related to significant down-regulation of miR319 target genes, implying their potential for use in the development of novel molecular strategies to genetically engineer crop species for enhanced resistance to environmental stress. PMID:23292790

  6. TaSnRK2.4, an SNF1-type serine/threonine protein kinase of wheat (Triticum aestivum L.), confers enhanced multistress tolerance in Arabidopsis

    PubMed Central

    Mao, Xinguo; Zhang, Hongying; Tian, Shanjun; Chang, Xiaoping; Jing, Ruilian

    2010-01-01

    Osmotic stresses such as drought, salinity, and cold are major environmental factors that limit agricultural productivity worldwide. Protein phosphorylation/dephosphorylation are major signalling events induced by osmotic stress in higher plants. Sucrose non-fermenting 1-related protein kinase2 family members play essential roles in response to hyperosmotic stresses in Arabidopsis, rice, and maize. In this study, the function of TaSnRK2.4 in drought, salt, and freezing stresses in Arabidopsis was characterized. A translational fusion protein of TaSnRK2.4 with green fluorescent protein showed subcellular localization in the cell membrane, cytoplasm, and nucleus. To examine the role of TaSnRK2.4 under various environmental stresses, transgenic Arabidopsis plants overexpressing wheat TaSnRK2.4 under control of the cauliflower mosaic virus 35S promoter were generated. Overexpression of TaSnRK2.4 resulted in delayed seedling establishment, longer primary roots, and higher yield under normal growing conditions. Transgenic Arabidopsis overexpressing TaSnRK2.4 had enhanced tolerance to drought, salt, and freezing stresses, which were simultaneously supported by physiological results, including decreased rate of water loss, enhanced higher relative water content, strengthened cell membrane stability, improved photosynthesis potential, and significantly increased osmotic potential. The results show that TaSnRK2.4 is involved in the regulation of enhanced osmotic potential, growth, and development under both normal and stress conditions, and imply that TaSnRK2.4 is a multifunctional regulatory factor in Arabidopsis. Since the overexpression of TaSnRK2.4 can significantly strengthen tolerance to drought, salt, and freezing stresses and does not retard the growth of transgenic Arabidopsis plants under well-watered conditions, TaSnRK2.4 could be utilized in transgenic breeding to improve abiotic stresses in crops. PMID:20022921

  7. Evolutionary engineering strategies to enhance tolerance of xylose utilizing recombinant yeast to inhibitors derived from spruce biomass

    PubMed Central

    2012-01-01

    Background One of the crucial factors for a sustainable and economical production of lignocellulosic based bioethanol is the availability of a robust fermenting microorganism with high tolerance to inhibitors generated during the pretreatment of lignocellulosic raw materials, since these inhibitors are known to severely hinder growth and fermentation. Results A long-term adaptation in repetitive batch cultures in shake flasks using a cocktail of 12 different inhibitors and a long-term chemostat adaptation using spruce hydrolysate were used as evolutionary engineering strategies to improve the inhibitor tolerance in the metabolically engineered xylose utilizing Saccharomyces cerevisiae strain, TMB3400. The yeast was evolved for a period of 429 and 97 generations in repetitive batch cultures and chemostat cultivation, respectively. During the evolutionary engineering in repetitive batch cultures the maximum specific growth rate increased from 0.18 h-1 to 0.33 h-1 and the time of lag phase was decreased from 48 h to 24 h. In the chemostat adaptation, after 97 generations, the specific conversion rates of HMF and furfural were found to be 3.5 and 4 folds higher respectively, compared to rates after three generations. Two evolved strains (RK60-5, RKU90-3) and one evolved strain (KE1-17) were isolated from evolutionary engineering in repetitive batches and chemostat cultivation, respectively. The strains displayed significantly improved growth performance over TMB3400 when cultivated in spruce hydrolysate under anaerobic conditions, the evolved strains exhibited 25 to 38% increase in specific consumption rate of sugars and 32 to 50% increased specific ethanol productivity compared to TMB3400. The evolved strains RK60-5 and RKU90-3 were unable to consume xylose under anaerobic conditions, whereas, KE1-17 was found to consume xylose at similar rates as TMB3400. Conclusion Using evolutionary engineering strategies in batch and chemostat cultivations we have generated three

  8. DAP12 deficiency in liver allografts results in enhanced donor DC migration, augmented effector T cell responses and abrogation of transplant tolerance

    PubMed Central

    Yoshida, O.; Kimura, S.; Dou, L.; Matta, B.M.; Yokota, S.; Stolz, D.B.; Geller, D.A.; Thomson, A. W.

    2014-01-01

    Liver interstitial dendritic cells (DC) have been implicated in immune regulation and tolerance induction. We found that the transmembrane immuno-adaptor DNAX-activating protein of 12kDa (DAP12) negatively regulated conventional liver myeloid (m) DC maturation and their in vivo migratory and T cell allostimulatory ability. Livers were transplanted from C57BL/6(H2b) (B6) wild-type (wt) or DAP12−/− mice into wt C3H (H2k) recipients. Donor mDC (H2-Kb+CD11c+) were quantified in spleens by flow cytometry. Anti-donor T cell reactivity was evaluated by ex vivo CFSE-MLR and delayed-type hypersensitivity responses, while T effector and regulatory T cells (Treg) were determined by flow analysis. A 3–4-fold increase in donor-derived DC was detected in spleens of DAP12−/− liver recipients compared with those given wt grafts. Moreover, pro-inflammatory cytokine gene expression in the graft, IFNγ production by graft-infiltrating CD8+ T cells, and systemic levels of IFNγ were all elevated significantly in DAP12−/− liver recipients. DAP12−/− grafts also exhibited reduced incidences of CD4+Foxp3+ cells and enhanced CD8+ T cell IFNγ secretion in response to donor antigen challenge. Unlike wt grafts, DAP12−/− livers failed to induce tolerance and were rejected acutely. Thus, DAP12 expression in liver grafts regulates donor mDC migration to host lymphoid tissue, alloreactive T cell responses and transplant tolerance. PMID:24935196

  9. Exercise Tolerance Can Be Enhanced through a Change in Work Rate within the Severe Intensity Domain: Work above Critical Power Is Not Constant

    PubMed Central

    Dekerle, Jeanne; de Souza, Kristopher Mendes; de Lucas, Ricardo Dantas; Guglielmo, Luiz Guilherme Antonacci; Greco, Camila Coelho; Denadai, Benedito Sérgio

    2015-01-01

    Introduction The characterization of the hyperbolic power-time (P-tlim) relationship using a two-parameter model implies that exercise tolerance above the asymptote (Critical Power; CP), i.e. within the severe intensity domain, is determined by the curvature (W’) of the relationship. Purposes The purposes of this study were (1) to test whether the amount of work above CP (W>CP) remains constant for varied work rate experiments of high volatility change and (2) to ascertain whether W’ determines exercise tolerance within the severe intensity domain. Methods Following estimation of CP (208 ± 19 W) and W’ (21.4 ± 4.2 kJ), 14 male participants (age: 26 ± 3; peak V˙O2: 3708 ± 389 ml.min-1) performed two experimental trials where the work rate was initially set to exhaust 70% of W’ in 3 (‘THREE’) or 10 minutes (‘TEN’) before being subsequently dropped to CP plus 10 W. Results W>CP for TEN (104 ± 22% W’) and W’ were not significantly different (P>0.05) but lower than W>CP for THREE (119 ± 17% W’, P<0.05). For both THREE (r = 0.71, P<0.01) and TEN (r = 0.64, P<0.01), a significant bivariate correlation was found between W’ and tlim. Conclusion W>CP and tlim can be greater than predicted by the P-tlim relationship when a decrement in the work rate of high-volatility is applied. Exercise tolerance can be enhanced through a change in work rate within the severe intensity domain. W>CP is not constant. PMID:26407169

  10. A novel allele of L-galactono-1,4-lactone dehydrogenase is associated with enhanced drought tolerance through affecting stomatal aperture in common wheat

    PubMed Central

    Zhang, Juncheng; Li, Bin; Yang, Yanping; Mu, Peiyuan; Qian, Weiqiang; Dong, Lingli; Zhang, Kunpu; Liu, Xin; Qin, Huanju; Ling, Hongqing; Wang, Daowen

    2016-01-01

    In higher plants, L-galactono-1,4-lactone dehydrogenase (GLDH) plays important roles in ascorbic acid (AsA) biosynthesis and assembly of respiration complex I. Here we report three homoeologous genes (TaGLDH-A1, -B1 and -D1) encoding common wheat GLDH isozymes and a unique allelic variant (TaGLDH-A1b) associated with enhanced drought tolerance. TaGLDH-A1, -B1 and -D1 were located on chromosomes 5A, 5B and 5D, respectively, and their transcripts were found in multiple organs. The three homoeologs each conferred increased GLDH activity when ectopically expressed in tobacco. Decreasing TaGLDH expression in wheat significantly reduced GLDH activity and AsA content. TaGLDH-A1b differed from wild type allele TaGLDH-A1a by an in-frame deletion of three nucleotides. TaGLDH-A1b was biochemically less active than TaGLDH-A1a, and the total GLDH activity levels were generally lower in the cultivars carrying TaGLDH-A1b relative to those with TaGLDH-A1a. Interestingly, TaGLDH-A1b cultivars showed stronger water deficiency tolerance than TaGLDH-A1a cultivars, and TaGLDH-A1b co-segregated with decreased leaf water loss in a F2 population. Finally, TaGLDH-A1b cultivars generally exhibited smaller leaf stomatal aperture than TaGLDH-A1a varieties in control or water deficiency environments. Our work provides new information on GLDH genes and function in higher plants. TaGLDH-A1b is likely useful for further studying and improving wheat tolerance to drought stress. PMID:27443220

  11. A novel allele of L-galactono-1,4-lactone dehydrogenase is associated with enhanced drought tolerance through affecting stomatal aperture in common wheat.

    PubMed

    Zhang, Juncheng; Li, Bin; Yang, Yanping; Mu, Peiyuan; Qian, Weiqiang; Dong, Lingli; Zhang, Kunpu; Liu, Xin; Qin, Huanju; Ling, Hongqing; Wang, Daowen

    2016-01-01

    In higher plants, L-galactono-1,4-lactone dehydrogenase (GLDH) plays important roles in ascorbic acid (AsA) biosynthesis and assembly of respiration complex I. Here we report three homoeologous genes (TaGLDH-A1, -B1 and -D1) encoding common wheat GLDH isozymes and a unique allelic variant (TaGLDH-A1b) associated with enhanced drought tolerance. TaGLDH-A1, -B1 and -D1 were located on chromosomes 5A, 5B and 5D, respectively, and their transcripts were found in multiple organs. The three homoeologs each conferred increased GLDH activity when ectopically expressed in tobacco. Decreasing TaGLDH expression in wheat significantly reduced GLDH activity and AsA content. TaGLDH-A1b differed from wild type allele TaGLDH-A1a by an in-frame deletion of three nucleotides. TaGLDH-A1b was biochemically less active than TaGLDH-A1a, and the total GLDH activity levels were generally lower in the cultivars carrying TaGLDH-A1b relative to those with TaGLDH-A1a. Interestingly, TaGLDH-A1b cultivars showed stronger water deficiency tolerance than TaGLDH-A1a cultivars, and TaGLDH-A1b co-segregated with decreased leaf water loss in a F2 population. Finally, TaGLDH-A1b cultivars generally exhibited smaller leaf stomatal aperture than TaGLDH-A1a varieties in control or water deficiency environments. Our work provides new information on GLDH genes and function in higher plants. TaGLDH-A1b is likely useful for further studying and improving wheat tolerance to drought stress. PMID:27443220

  12. Cloning and characterization of a maize SnRK2 protein kinase gene confers enhanced salt tolerance in transgenic Arabidopsis.

    PubMed

    Ying, Sheng; Zhang, Deng-Feng; Li, Hui-Yong; Liu, Ying-Hui; Shi, Yun-Su; Song, Yan-Chun; Wang, Tian-Yu; Li, Yu

    2011-09-01

    SnRK2 (sucrose non-fermenting 1-related protein kinases 2) represents a unique family of protein kinase in regulating signaling transduction in plants. Although the regulatory mechanisms of SnRK2 have been well demonstrated in Arabidopsis thaliana, their functions in maize are still unknown. In our study, we cloned an SnRK2 gene from maize, ZmSAPK8, which encoded a putative homolog of the rice SAPK8 protein. ZmSAPK8 had two copies in the maize genome and harbored eight introns in its coding region. We demonstrated that ZmSAPK8 expressed differentially in various organs of maize plants and was up-regulated by high-salinity and drought treatment. A green fluorescent protein (GFP)-tagged ZmSAPK8 showed subcellular localization in the cell membrane, cytoplasm and nucleus. In vitro kinase assays indicated that ZmSAPK8 preferred Mn(2+) to Mg(2+) as cofactor for phosphorylation, and Ser-182 and Thr-183 in activation loop was important for its activity. Heterologous overexpression of ZmSAPK8 in Arabidopsis could significantly strengthen tolerance to salt stress. Under salt treatment, ZmSAPK8-overexpressed transgenic plants exhibited higher germination rate and proline content, low electrolyte leakage and higher survival rate than wild type. Further analysis indicated that transgenic plants showed increased transcription of the stress-related genes, RD29A, RD29B, RAB18, ABI1, DREB2A and P5CS1, under high-salinity conditions. The results demonstrated that ZmSAPK8 was involved in diverse stress signal transduction. Moreover, no obvious adverse effects on growth and development in the ZmSAPK8-overexpressed transgenic plants implied that ZmSAPK8 was potentially useful in transgenic breeding to improve salt tolerance in crops. PMID:21638061

  13. Hydrogen sulfide enhances salt tolerance through nitric oxide-mediated maintenance of ion homeostasis in barley seedling roots

    PubMed Central

    Chen, Juan; Wang, Wen-Hua; Wu, Fei-Hua; He, En-Ming; Liu, Xiang; Shangguan, Zhou-Ping; Zheng, Hai-Lei

    2015-01-01

    Hydrogen sulfide (H2S) and nitric oxide (NO) are emerging as messenger molecules involved in the modulation of plant physiological processes. Here, we investigated a signalling network involving H2S and NO in salt tolerance pathway of barley. NaHS, a donor of H2S, at a low concentration of either 50 or 100 μM, had significant rescue effects on the 150 mM NaCl-induced inhibition of plant growth and modulated the K+/Na+ balance by decreasing the net K+ efflux and increasing the gene expression of an inward-rectifying potassium channel (HvAKT1) and a high-affinity K+ uptake system (HvHAK4). H2S and NO maintained the lower Na+ content in the cytoplast by increasing the amount of PM H+-ATPase, the transcriptional levels of PM H+-ATPase (HvHA1) and Na+/H+ antiporter (HvSOS1). H2S and NO modulated Na+ compartmentation into the vacuoles with up-regulation of the transcriptional levels of vacuolar Na+/H+ antiporter (HvVNHX2) and H+-ATPase subunit β (HvVHA-β) and increased in the protein expression of vacuolar Na+/H+ antiporter (NHE1). H2S mimicked the effect of sodium nitroprusside (SNP) by increasing NO production, whereas the function was quenched with the addition of NO scavenger. These results indicated that H2S increased salt tolerance by maintaining ion homeostasis, which were mediated by the NO signal. PMID:26213372

  14. Does trophic status enhance or reduce the thermal tolerance of scleractinian corals? A review, experiment and conceptual framework.

    PubMed

    Fabricius, Katharina E; Cséke, Szilvia; Humphrey, Craig; De'ath, Glenn

    2013-01-01

    Global warming, and nutrient and sediment runoff from coastal development, both exert increasing pressures on coastal coral reefs. The objective of this study was to resolve the question of whether coastal eutrophication may protect corals from thermal stress by improving their nutritional status, or rather diminish their thermal tolerance through the synergy of dual stressors. A review of previous studies on the topic of combined trophic status and heat exposure on the thermal tolerance of corals reveals a broad range of outcomes, including synergistic, additive and antagonistic effects. We conducted a 90-day long experiment exposing corals to realistic levels of elevated nutrients and sediments, and heat stress. Colonies of two common scleractinian corals (Acropora millepora and Montipora tuberculosa) were kept in coastal seawater, or coastal seawater that was further organically and nutrient enriched (OE), and/or enriched with nitrate. Batches of OE were created daily, facilitating nutrient uptake, plankton succession and organic enrichment as observed in coastal waters. After 10 days of acclimation, 67% of the colonies had their temperature gradually increased from 27° to 31.2°C. After 3-7 weeks of heat stress, colonies of both species had significantly greater reductions in fluorescence yields and lower survival in OE than without addition of OE. Furthermore, photophysiological recovery was incomplete 31-38 days after ending the heat stress only in the OE treatments. Nitrate alone had no measurable effect on survival, bleaching and recovery in either species. Skeletal growth rates were reduced by 45% in heat-stressed A. millepora and by 24% in OE-exposed M. tuberculosa. We propose a conceptual trophic framework that resolves some of the apparently contradictory outcomes revealed by the review. Our study shows that management actions to reduce coastal eutrophication can improve the resistance and resilience of vulnerable coastal coral reefs to warming

  15. Cloning, heterologous expression and characterization of ascorbate peroxidase (APX) gene in laticifer cells of rubber tree (Hevea brasiliensis Muell. Arg.).

    PubMed

    Chao, Jinquan; Zhang, Shixin; Chen, Yueyi; Tian, Wei-Min

    2015-12-01

    Ascorbate peroxidases (APXs) are a kind of crucial enzymes for removing reactive oxygen species (ROS) in plant cell. In the present study, a full-length cDNA encoding an APX, designated HbAPX, was isolated from Hevea brasiliensis by the rapid amplification of cDNA ends (RACE) method. HbAPX was 1174-bp in length and contained a 912-bp open reading frame (ORF) encoding a putative protein of 304 amino acids. The predicted molecular mass of HbAPX was 27.6 kDa (kDa) with an isoelectric point (pI) of 6.73. The phylogenetic analysis showed that HbAPX belonged to the cytosolic subgroup and was more relative to PtAPX and MdAPX2. By using PlantCare online analysis, such cis-acting elements as W-box and MRE were detected in the promoter region of HbAPX. Overproduction of recombinant HbAPX protein either in Escherichia coli or yeast enhanced their tolerance to such abiotic stresses as Cu(2+), Zn(2+), Na(2+) and hydrogen peroxide (H2O2). Ethrel application significantly down-regulated the expression of HbAPX and inhibited the activity of HbAPX in vivo. The ethrel-caused down-regulation of HbAPX may disturb the redox homeostasis in laticifer cells of rubber tree. PMID:26519821

  16. The Reaction of Coumarins with Horseradish Peroxidase 1

    PubMed Central

    Miller, Richard W.; Sirois, J.-Claude; Morita, Hirokazu

    1975-01-01

    The peroxidase catalyzed oxidation of indole-3-acetate is inhibited by naturally occurring coumarins such as scopoletin. This inhibition is due to the preferential reactivity of the coumarins with the peroxidase compounds I, II, and III. In view of the possible growth regulatory role of coumarins in plants, the mechanism of oxidation of scopoletin by horse-radish peroxidase has been investigated. Peroxidase catalyzed coumarin oxidation requires either an electron donor and molecular oxygen or hydrogen peroxide. If peroxide is present, the reaction is mediated by peroxidase compound II which reacts rapidly and stoichiometrically with scopoletin. Different oxidation products are formed, depending on whether IAA or hydrogen peroxide promotes the reaction. A scopoletin-free radical intermediate has been isolated from the peroxide reaction mixture but was not detected in the peroxide-free system. When indole-3-acetate is the electron donor, reduced peroxidase combines with molecular oxygen to give peroxidase compound III. Added scopoletin is cooxidized with indole-3-acetate. Compared to the scopoletin peroxidation, this reaction is slower and yields fewer coumarin oxidation products. The differences observed between the two scopoletin oxidation pathways reflect: (a) the competition between indole-3-acetate and scopoletin for peroxidase compounds; (b) the lower reactivity of scopoletin with peroxidase compound III compared with peroxidase compound II. The peroxide-promoted reaction is eliminated by catalase, while the indole-3-acetate initiated oxidation is not affected by excess quantities of either catalase or superoxidase dismutase. PMID:16659024

  17. A PI 4. 6 peroxidase that specifically crosslinks extensin precursors

    SciTech Connect

    Upham, B.L; Alizadeh, H.; Ryan, K.J.; Lamport, D.T.A. )

    1991-05-01

    The primary cell wall is a microcomposite of cellulose, pectin, hemicellulose and protein. The warp-weft model of the primary cell wall hypothesize that extensin monomers are intermolecularly crosslinked orthogonal to the cellulose microfibril thus mechanically coupling the major load-bearing polymer: cellulose. Media of tomato cell cultures contains heat labile, peroxide dependent crosslinking activity, as determined by the rate of decrease in monomer concentration analyzed via Superose-6. Isoelectric focusing of tomato cell culture media indicated crosslinking was predominantly in the acidic peroxidase fraction (pI4.6). This peroxidase was partially purified by ultracentrifugation, DEAE-Trisacryl and HPLC-DEAE chromatography techniques resulting in a 90 fold purification and 45% yield. A second acidic peroxidase eluted from the HPLC-DEAE column had 25% of the crosslinking activity of the pI 4.6 peroxidase. Purified basic peroxidase had only 0.7% of the activity of the pI 4.6 peroxidase. The specific activity of the pI 4.6 peroxidase was 5,473 mg extensin crosslinked/min/mg peroxidase. The pI 4.6 peroxidase crosslinked the following extensins: tomato I and II, carrot, Ginkgo II and did not crosslink Ginkgo I, Douglas Fir, Maize, Asparagus I and II, and sugarbeet extensins as well as bovine serum albumin. Comparison of motifs common to extensins that are crosslinked by the pI 4.6 peroxidase may help identify the crosslink domain(s) of extension.

  18. Constitutive Expression of Rice MicroRNA528 Alters Plant Development and Enhances Tolerance to Salinity Stress and Nitrogen Starvation in Creeping Bentgrass.

    PubMed

    Yuan, Shuangrong; Li, Zhigang; Li, Dayong; Yuan, Ning; Hu, Qian; Luo, Hong

    2015-09-01

    MicroRNA528 (miR528) is a conserved monocot-specific small RNA that has the potential of mediating multiple stress responses. So far, however, experimental functional studies of miR528 are lacking. Here, we report that overexpression of a rice (Oryza sativa) miR528 (Osa-miR528) in transgenic creeping bentgrass (Agrostis stolonifera) alters plant development and improves plant salt stress and nitrogen (N) deficiency tolerance. Morphologically, miR528-overexpressing transgenic plants display shortened internodes, increased tiller number, and upright growth. Improved salt stress resistance is associated with increased water retention, cell membrane integrity, chlorophyll content, capacity for maintaining potassium homeostasis, CATALASE activity, and reduced ASCORBIC ACID OXIDASE (AAO) activity; while enhanced tolerance to N deficiency is associated with increased biomass, total N accumulation and chlorophyll synthesis, nitrite reductase activity, and reduced AAO activity. In addition, AsAAO and COPPER ION BINDING PROTEIN1 are identified as two putative targets of miR528 in creeping bentgrass. Both of them respond to salinity and N starvation and are significantly down-regulated in miR528-overexpressing transgenics. Our data establish a key role that miR528 plays in modulating plant growth and development and in the plant response to salinity and N deficiency and indicate the potential of manipulating miR528 in improving plant abiotic stress resistance. PMID:26224802

  19. Enhanced tolerance and remediation to mixed contaminates of PCBs and 2,4-DCP by transgenic alfalfa plants expressing the 2,3-dihydroxybiphenyl-1,2-dioxygenase.

    PubMed

    Wang, Yan; Ren, Hejun; Pan, Hongyu; Liu, Jinliang; Zhang, Lanying

    2015-04-01

    Polychlorinated biphenyls (PCBs) and 2,4-dichlorophenol (2,4-DCP) generally led to mixed contamination of soils as a result of commercial and agricultural activities. Their accumulation in the environment poses great risks to human and animal health. Therefore, the effective strategies for disposal of these pollutants are urgently needed. In this study, genetic engineering to enhance PCBs/2,4-DCP phytoremediation is a focus. We cloned the 2,3-dihydroxybiphenyl-1,2-dioxygenase (BphC.B) from a soil metagenomic library, which is the key enzyme of aerobic catabolism of a variety of aromatic compounds, and then it was expressed in alfalfa driven by CaMV 35S promoter using Agrobacterium-mediated transformation. Transgenic line BB11 was selected out through PCR, Western blot analysis and enzyme activity assays. Its disposal and tolerance to both PCBs and 2,4-DCP were examined. The tolerance capability of transgenic line BB11 towards complex contaminants of PCBs/2,4-DCP significantly increased compared with non-transgenic plants. Strong dissipation of PCBs and high removal efficiency of 2,4-DCP were exhibited in a short time. It was confirmed expressing BphC.B would be a feasible strategy to help achieving phytoremediation in mixed contaminated soils with PCBs and 2,4-DCP. PMID:25590820

  20. Maize ABP9 enhances tolerance to multiple stresses in transgenic Arabidopsis by modulating ABA signaling and cellular levels of reactive oxygen species.

    PubMed

    Zhang, Xia; Wang, Lei; Meng, Hui; Wen, Hongtao; Fan, Yunliu; Zhao, Jun

    2011-03-01

    The phytohormone abscisic acid (ABA) and reactive oxygen species (ROS) play critical roles in mediating abiotic stress responses in plants. It is well known that ABA is involved in the modulation of ROS levels by regulating ROS-producing and ROS-scavenging genes, but the molecular mechanisms underlying this regulation are poorly understood. Here we show that the expression of maize ABP9 gene, which encodes a bZIP transcription factor capable of binding to the ABRE2 motif in the maize Cat1 promoter, is induced by ABA, H(2)O(2), drought and salt. Constitutive expression of ABP9 in transgenic Arabidopsis leads to remarkably enhanced tolerance to multiple stresses including drought, high salt, freezing temperature and oxidative stresses. ABP9 expressing Arabidopsis plants also exhibit increased sensitivity to exogenously applied ABA during seed germination, root growth and stomatal closure and improved water-conserving capacity. Moreover, constitutive expression of ABP9 causes reduced cellular levels of ROS, alleviated oxidative damage and reduced cell death, accompanied by elevated expression of many stress/ABA responsive genes including those for scavenging and regulating ROS. Taken together, these results suggest that ABP9 may play a pivotal role in plant tolerance to abiotic stresses by fine tuning ABA signaling and control of ROS accumulation. PMID:21327835

  1. Enhanced Photosynthesis and Carbon Metabolism Favor Arsenic Tolerance in Artemisia annua, a Medicinal Plant as Revealed by Homology-Based Proteomics

    PubMed Central

    Pandey, Sarita; Shrivastava, Alok Kumar; Pandey Rai, Shashi

    2014-01-01

    This paper provides the first proteomic evidence of arsenic (As) tolerance and interactive regulatory network between primary and secondary metabolism in the medicinal plant, Artemisia annua. While chlorophyll fluorescence and photosynthetic rate depicted mild inhibition, there was a significant enhancement in PSI activity, whole chain, ATP, and NADPH contents in 100 μM As treatments compared to the control plants. However, a decrease in the above variables was recorded under 150 μM treatments. Proteomic decoding of the survival strategy of A. annua under As stress using 2-DE followed by MALDI-MS/MS revealed a total of 46 differentially expressed protein spots. In contrast to other plants where As inhibits photosynthesis, A. annua showed appreciable photosynthetic CO2 assimilation and allocation of carbon resources at 100 μM As concentration. While an increased accumulation of ATP synthase, ferredoxin-NADP(H) oxidoreductase, and FeS-rieske proteins supported the operation of cyclic electron transport, mdr ABC transporter protein and pcs gene might be involved in As detoxification. The most interesting observation was an increased accumulation of LEAFY like novel protein conceivably responsible for an early onset of flowering in A. annua under As stress. This study not only affirmed the role of energy metabolism proteins but also identified potential candidates responsible for As tolerance in plants. PMID:24868464

  2. Constitutive Expression of Rice MicroRNA528 Alters Plant Development and Enhances Tolerance to Salinity Stress and Nitrogen Starvation in Creeping Bentgrass1[OPEN

    PubMed Central

    Yuan, Shuangrong; Li, Zhigang; Li, Dayong; Yuan, Ning; Hu, Qian; Luo, Hong

    2015-01-01

    MicroRNA528 (miR528) is a conserved monocot-specific small RNA that has the potential of mediating multiple stress responses. So far, however, experimental functional studies of miR528 are lacking. Here, we report that overexpression of a rice (Oryza sativa) miR528 (Osa-miR528) in transgenic creeping bentgrass (Agrostis stolonifera) alters plant development and improves plant salt stress and nitrogen (N) deficiency tolerance. Morphologically, miR528-overexpressing transgenic plants display shortened internodes, increased tiller number, and upright growth. Improved salt stress resistance is associated with increased water retention, cell membrane integrity, chlorophyll content, capacity for maintaining potassium homeostasis, CATALASE activity, and reduced ASCORBIC ACID OXIDASE (AAO) activity; while enhanced tolerance to N deficiency is associated with increased biomass, total N accumulation and chlorophyll synthesis, nitrite reductase activity, and reduced AAO activity. In addition, AsAAO and COPPER ION BINDING PROTEIN1 are identified as two putative targets of miR528 in creeping bentgrass. Both of them respond to salinity and N starvation and are significantly down-regulated in miR528-overexpressing transgenics. Our data establish a key role that miR528 plays in modulating plant growth and development and in the plant response to salinity and N deficiency and indicate the potential of manipulating miR528 in improving plant abiotic stress resistance. PMID:26224802

  3. PsAP2 an AP2/ERF family transcription factor from Papaver somniferum enhances abiotic and biotic stress tolerance in transgenic tobacco.

    PubMed

    Mishra, Sonal; Phukan, Ujjal J; Tripathi, Vineeta; Singh, Dhananjay K; Luqman, Suaib; Shukla, Rakesh Kumar

    2015-09-01

    The AP2/ERFs are one of the most important family of transcription factors which regulate multiple responses like stress, metabolism and development in plants. We isolated PsAP2 a novel AP2/ERF from Papaver somniferum which was highly upregulated in response to wounding followed by ethylene, methyl jasmonate and ABA treatment. PsAP2 showed specific binding with both DRE and GCC box elements and it was able to transactivate the reporter genes in yeast. PsAP2 overexpressing transgenic tobacco plants exhibited enhanced tolerance towards both abiotic and biotic stresses . Real time transcript expression analysis showed constitutive upregulation of tobacco Alternative oxidase1a and Myo-inositol-1-phosphate synthase in PsAP2 overexpressing tobacco plants. Further, PsAP2 showed interaction with NtAOX1a promoter in vitro, it also specifically activated the NtAOX1a promoter in yeast and tobacco BY2 cells. The silencing of PsAP2 using VIGS lead to significant reduction in the AOX1 level in P. somniferum. Taken together PsAP2 can directly bind and transcriptionally activate NtAOX1a and its overexpression in tobacco imparted increased tolerance towards both abiotic and biotic stress. PMID:26319514

  4. Co-transforming bar and CsLEA enhanced tolerance to drought and salt stress in transgenic alfalfa (Medicago sativa L.).

    PubMed

    Zhang, Jiyu; Duan, Zhen; Zhang, Daiyu; Zhang, Jianquan; Di, Hongyan; Wu, Fan; Wang, Yanrong

    2016-03-25

    Drought and high salinity are two major abiotic factors that restrict alfalfa productivity. A dehydrin protein, CsLEA, from the desert grass Cleistogenes songorica was transformed into alfalfa (Medicago sativa L.) via Agrobacterium-mediated transformation using the bar gene as a selectable marker, and the drought and salt stress tolerances of the transgenic plants were assessed. Thirty-nine of 119 transformants were positive, as screened by Basta, and further molecularly authenticated using PCR and RT-PCR. Phenotype observations revealed that the transgenic plants grew better than the wild-type (WT) plants after 15d of drought stress and 10d of salt stress: the leaves of WT alfalfa turned yellow, whereas the transgenic alfalfa leaves only wilted; after rewatering, the transgenic plants returned to a normal state, though the WT plants could not be restored. Evaluation of physiologic and biochemical indices during drought and salt stresses showed a relatively lower Na(+) content in the leaves of the transgenic plants, which would reduce toxic ion effects. In addition, the transgenic plants were able to maintain a higher relative water content (RWC), higher shoot biomass, fewer photosystem changes, decreased membrane injury, and a lower level of osmotic stress injury. These results demonstrate that overexpression of the CsLEA gene can enhance the drought and salt tolerance of transgenic alfalfa; in addition, carrying the bar gene in the genome may increase herbicide resistance. PMID:26906624

  5. The limits of drought-induced rapid cold-hardening: extremely brief, mild desiccation triggers enhanced freeze-tolerance in Eurosta solidaginis larvae.

    PubMed

    Gantz, J D; Lee, Richard E

    2015-02-01

    Rapid cold-hardening (RCH) is a highly conserved response in insects that induces physiological changes within minutes to hours of exposure to low temperature and provides protection from chilling injury. Recently, a similar response, termed drought-induced RCH, was described following as little as 6h of desiccation, producing a loss of less than 10% of fresh mass. In this study, we investigated the limits and mechanisms of this response in larvae of the goldenrod gall fly Eurosta solidaginis (Diptera, Tephritidae). The cold-hardiness of larvae increased markedly after as few as 2h of desiccation and a loss of less than 1% fresh mass, as organismal survival increased from 8% to 41% following exposure to -18 °C. Tissue-level effects of desiccation were observed within 1h, as 87% of midgut cells from desiccated larvae remained viable following freezing compared to 57% of controls. We also demonstrated that drought-induced RCH occurs independently of neuroendocrine input, as midgut tissue desiccated ex vivo displayed improved freeze-tolerance relative to control tissue (78-11% survival, respectively). Finally, though there was an increase in hemolymph osmolality beyond the expected effects of the osmo-concentration of solutes during dehydration, we determined that this increase was not due to the synthesis of glycerol, glucose, sorbitol, or trehalose. Our results indicate that E. solidaginis larvae are extremely sensitive to desiccation, which is a triggering mechanism for one or more physiological pathways that confer enhanced freeze-tolerance. PMID:25545423

  6. Induction of 33-kD and 60-kD peroxidases during ethylene-induced senescence of cucumber cotyledons. [Cucumis sativus L

    SciTech Connect

    Abeles, F.B.; Dunn, L.J.; Morgens, P.; Callahan, A.; Dinterman, R.E.; Schmidt, J. Army Medical Research Institute for Infectious Diseases, Frederick, MD )

    1988-07-01

    Ethylene enhanced the senescence of cucumber (Cucumis sativus L. cv Poinsett 76) cotyledons. The effect of 10 microliters per liter ethylene was inhibited by 1 millimolar silver thiosulfate, an inhibitor of ethylene action. An increase in proteins with molecular weights of 33 to 30 kilodaltons and lower molecular weights (25, 23, 20, 16, 12 and 10 kilodaltons) were observed in sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels after ethylene enhanced senescence. The measurement of DNase and RNase activity in gels indicated that these new proteins were not nucleases. Two proteins from ethylene-treated cotyledons were purified on the basis of their association with a red chromaphore and subsequently were identified as peroxidases. The molecular weights and isoelectric points (pI) of two of these peroxidases were 33 kilodaltons (cationic, pI = 8.9) and 60 kilodaltons (anionic, pI = 4.0). The observation that ({sup 35}S)Na{sub 2}SO{sub 4} was incorporated into these proteins during ethylene-enhanced senescence suggests that these peroxidases represent newly synthesized proteins. Antibodies to the 33-kilodalton peroxidase precipitated two in vitro translation products from RNA isolated from ethylene-treated but not from control cucumber seedlings. This indicates that the increase in 33-kilodalton peroxidase activity represents de novo protein synthesis. Both forms of peroxidase degraded chlorophyll in vitro, which is consistent with the hypothesis that peroxidases have catabolic or scavenging functions in senescent tissues.

  7. A novel cold-regulated gene from Camellia sinensis, CsCOR1, enhances salt- and dehydration-tolerance in tobacco

    SciTech Connect

    Li, Xian-Wen; Feng, Zhi-Guo; Yang, Hui-Min; Zhu, Xiao-Pei; Liu, Jun; Yuan, Hong-Yu

    2010-04-02

    In present research, the full-length cDNA and the genomic sequence of a novel cold-regulated gene, CsCOR1, were isolated from Camellia sinensis L. The deduced protein CsCOR1 contains a hydrophobic N-terminus as a signal peptide and a hydrophilic C-terminal domain that is rich in glycine, arginine and proline. Two internal repetitive tridecapeptide fragments (HSVTAGRGGYNRG) exist in the middle of the C-terminal domain and the two nucleotide sequences encoding them are identical. CsCOR1 was localized in the cell walls of transgenic-tobaccos via CsCOR1::GFP fusion approach. The expression of CsCOR1 in tea leaves was enhanced dramatically by both cold- and dehydration-stress. And overexpression of CsCOR1 in transgenic-tobaccos improved obviously the tolerance to salinity and dehydration.

  8. A synthetic triacylated pseudo-dipeptide molecule promotes Th1/TReg immune responses and enhances tolerance induction via the sublingual route.

    PubMed

    Mascarell, Laurent; Van Overtvelt, Laurence; Lombardi, Vincent; Razafindratsita, Alain; Moussu, Hélène; Horiot, Stéphane; Chabre, Henri; Limal, David; Moutel, Stéphane; Bauer, Jacques; Chiavaroli, Carlo; Moingeon, Philippe

    2007-12-21

    In this study, we tested two triacylated pseudo-dipeptidic molecules, OM-197-MP-AC and OM-294-BA-MP as candidate adjuvants for allergy vaccines. Both molecules induce human dendritic cell (h-DC) maturation and polarize naïve T cells toward the Th1 type with IFNgamma production. Only OM-294-BA-MP induces IL10 gene expression both in monocyte-derived DCs and CD4+ naïve T cells. Sublingual administration of OM-294-BA-MP plus the antigen enhances tolerance induction in BALB/c mice with established asthma to ovalbumin with an impact on both airways hyperresponsiveness and lung inflammation. Given its Th1/Treg polarizing properties, OM-294-BA-MP is a valid candidate for sublingual allergy vaccines. PMID:18063445

  9. Duplicate and Conquer: Multiple Homologs of PHOSPHORUS-STARVATION TOLERANCE1 Enhance Phosphorus Acquisition and Sorghum Performance on Low-Phosphorus Soils1[C][W][OPEN

    PubMed Central

    Hufnagel, Barbara; de Sousa, Sylvia M.; Assis, Lidianne; Guimaraes, Claudia T.; Leiser, Willmar; Azevedo, Gabriel C.; Negri, Barbara; Larson, Brandon G.; Shaff, Jon E.; Pastina, Maria Marta; Barros, Beatriz A.; Weltzien, Eva; Rattunde, Henry Frederick W.; Viana, Joao H.; Clark, Randy T.; Falcão, Alexandre; Gazaffi, Rodrigo; Garcia, Antonio Augusto F.; Schaffert, Robert E.; Kochian, Leon V.; Magalhaes, Jurandir V.

    2014-01-01

    Low soil phosphorus (P) availability is a major constraint for crop production in tropical regions. The rice (Oryza sativa) protein kinase, PHOSPHORUS-STARVATION TOLERANCE1 (OsPSTOL1), was previously shown to enhance P acquisition and grain yield in rice under P deficiency. We investigated the role of homologs of OsPSTOL1 in sorghum (Sorghum bicolor) performance under low P. Association mapping was undertaken in two sorghum association panels phenotyped for P uptake, root system morphology and architecture in hydroponics and grain yield and biomass accumulation under low-P conditions, in Brazil and/or in Mali. Root length and root surface area were positively correlated with grain yield under low P in the soil, emphasizing the importance of P acquisition efficiency in sorghum adaptation to low-P availability. SbPSTOL1 alleles reducing root diameter were associated with enhanced P uptake under low P in hydroponics, whereas Sb03g006765 and Sb03g0031680 alleles increasing root surface area also increased grain yield in a low-P soil. SbPSTOL1 genes colocalized with quantitative trait loci for traits underlying root morphology and dry weight accumulation under low P via linkage mapping. Consistent allelic effects for enhanced sorghum performance under low P between association panels, including enhanced grain yield under low P in the soil in Brazil, point toward a relatively stable role for Sb03g006765 across genetic backgrounds and environmental conditions. This study indicates that multiple SbPSTOL1 genes have a more general role in the root system, not only enhancing root morphology traits but also changing root system architecture, which leads to grain yield gain under low-P availability in the soil. PMID:25189534

  10. Overexpression of copper/zinc superoxide dismutase from mangrove Kandelia candel in tobacco enhances salinity tolerance by the reduction of reactive oxygen species in chloroplast

    PubMed Central

    Jing, Xiaoshu; Hou, Peichen; Lu, Yanjun; Deng, Shurong; Li, Niya; Zhao, Rui; Sun, Jian; Wang, Yang; Han, Yansha; Lang, Tao; Ding, Mingquan; Shen, Xin; Chen, Shaoliang

    2015-01-01

    Na+ uptake and transport in Kandelia candel and antioxidative defense were investigated under rising NaCl stress from 100 to 300 mM. Salinized K. candel roots had a net Na+ efflux with a declined flux rate during an extended NaCl exposure. Na+ buildup in leaves enhanced H2O2 levels, superoxide dismutase (SOD) activity, and increased transcription of CSD gene encoding a Cu/Zn SOD. Sequence and subcellular localization analyses have revealed that KcCSD is a typical Cu/Zn SOD in chloroplast. The transgenic tobacco experimental system was used as a functional genetics model to test the effect of KcCSD on salinity tolerance. KcCSD-transgenic lines were more Na+ tolerant than wild-type (WT) tobacco in terms of lipid peroxidation, root growth, and survival rate. In the latter, 100 mM NaCl led to a remarkable reduction in chlorophyll content and a/b ratio, decreased maximal chlorophyll a fluorescence, and photochemical efficiency of photosystem II. NaCl stress in WT resulted from H2O2 burst in chloroplast. Na+ injury to chloroplast was less pronounced in KcCSD-transgenic plants due to upregulated antioxidant defense. KcCSD-transgenic tobacco enhanced SOD activity by an increment in SOD isoenzymes under 100 mM NaCl stress from 24 h to 7 day. Catalase activity rose in KcCSD overexpressing tobacco plants. KcCSD-transgenic plants better scavenged NaCl-elicited reactive oxygen species (ROS) compared to WT ones. In conclusion, K. candel effectively excluded Na+ in roots during a short exposure; and increased CSD expression to reduce ROS in chloroplast in a long-term and high saline environment. PMID:25657655

  11. Tolerability and efficacy of newly developed penile injection of cross-linked dextran and polymethylmethacrylate mixture on penile enhancement: 6 months follow-up.

    PubMed

    Yang, D Y; Lee, W K; Kim, S C

    2013-05-01

    Cross-linked dextran and polymethylmethacrylate mixture (Lipen-10) is newly developed tissue filler. The purpose of this study was to evaluate tolerability and efficacy of Lipen-10 on penile enhancement. Twenty adult males were included in this study. Lipen-10 was injected into the subcutaneous tissue of the penile shaft. The penile girth and length were measured in the flaccid state, before and 1, 3 and 6 months after the injection. The circumference increased by 3.7±1.2 cm (50.8%, P<0.0001) at penile base, 4.2±0.9 cm (59.0%, P<0.001) at mid-shaft, and 3.8±1.0 cm (53.2%, P<0.0001) at distal shaft and the length increased by 2.3±1.4 cm (63.2%, P<0.001). There was, however, no significant difference between 3 and 6 months post-treatment in girth and length (P-values: 0.796, 0.498, 0.600 and 0.084 for penile base, mid- and distal-shaft and length, respectively). The complications were only one mild asymmetry of penile shape and one 5-mm-sized nodule in the injected site. There were no clinically significant adverse events in all subjects. Penile injection of Lipen-10 led to a significant increase in penile size, showed a good durability and was well-tolerated, without serious adverse events. These results suggest that penile injection of Lipen-10 may be a new effective method for penile enhancement. PMID:23171980

  12. Co-expression of xerophyte Zygophyllum xanthoxylum ZxNHX and ZxVP1-1 confers enhanced salinity tolerance in chimeric sugar beet (Beta vulgaris L.)

    PubMed Central

    Wu, Guo-Qiang; Feng, Rui-Jun; Wang, Suo-Min; Wang, Chun-Mei; Bao, Ai-Ke; Wei, Li; Yuan, Hui-Jun

    2015-01-01

    Salinity is one of the major abiotic stresses that limit the growth and productivity of sugar beet (Beta vulgaris L.). To improve sugar beet’s salinity tolerance, the ZxNHX and ZxVP1-1 genes encoding tonoplast Na+/H+ antiporter and H+-PPase from xerophyte Zygophyllum xanthoxylum were co-expressed by Agrobacterium tumefaciens-mediated transformation. It is showed here that co-expression of ZxNHX and ZxVP1-1 confers enhanced salinity tolerance to the transformed sugar beet plants compared with the wild-type (WT) plants. The chimeric plants grew well in the presence of high salinity (400 mM NaCl), whereas WT plants displayed chlorosis and died within 8 days. Compared to WT plants, the chimeric plants co-expressing ZxNHX and ZxVP1-1 accumulated more proline, Na+ and K+ in their leaves and petioles when exposed to high salinity, which caused lower solute potential, retained more water and thus subjected to lesser cell membrane damage. Interestingly, the chimeric plants accumulated higher sucrose, glucose and fructose contents in their storage roots than WT plants in the absence or presence of high salinity. Our results suggested that co-expression of ZxNHX and ZxVP1-1 improved the osmoregulatory capacity in chimeric sugar beet through increased compartmentalization of ions into the vacuoles by enhancing the activity of proton pumps and thus mitigated Na+-toxicity for plants. PMID:26284097

  13. Two cationic peroxidases from cell walls of Araucaria araucana seeds.

    PubMed

    Riquelme, A; Cardemil, L

    1995-05-01

    We have previously reported the purification and partial characterization of two cationic peroxidases from the cell walls of seeds and seedlings of the South American conifer, Araucaria araucana. In this work, we have studied the amino acid composition and NH2-terminal sequences of both enzymes. We also compare the data obtained from these analyses with those reported for other plant peroxidases. The two peroxidases are similar in their amino acid compositions. Both are particularly rich in glycine, which comprises more than 30% of the amino acid residues. The content of serine is also high, ca 17%. The two enzymes are different in their content of arginine, alanine, valine, phenylalanine and threonine. Both peroxidases have identical NH2-terminal sequences, indicating that the two proteins are genetically related and probably are isoforms of the same kind of peroxidase. The amino acid composition and NH2-terminal sequence analyses showed marked differences from the cationic peroxidases from turnip and horseradish. PMID:7786490

  14. Overexpression of MdbHLH104 gene enhances the tolerance to iron deficiency in apple.

    PubMed

    Zhao, Qiang; Ren, Yi-Ran; Wang, Qing-Jie; Yao, Yu-Xin; You, Chun-Xiang; Hao, Yu-Jin

    2016-07-01

    Fe deficiency is a widespread nutritional disorder in plants. The basic helix-loop-helix (bHLH) transcription factors (TFs), especially Ib subgroup bHLH TFs which are involved in iron uptake, have been identified. In this study, an IVc subgroup bHLH TF MdbHLH104 was identified and characterized as a key component in the response to Fe deficiency in apple. The overexpression of the MdbHLH104 gene noticeably increased the H(+) -ATPase activity under iron limitation conditions and the tolerance to Fe deficiency in transgenic apple plants and calli. Further investigation showed that MdbHLH104 proteins bonded directly to the promoter of the MdAHA8 gene, thereby positively regulating its expression, the plasma membrane (PM) H(+) -ATPase activity and Fe uptake. Similarly, MdbHLH104 directly modulated the expression of three Fe-responsive bHLH genes, MdbHLH38, MdbHLH39 and MdPYE. In addition, MdbHLH104 interacted with 5 other IVc subgroup bHLH proteins to coregulate the expression of the MdAHA8 gene, the activity of PM H(+) -ATPase and the content of Fe in apple calli. Therefore, MdbHLH104 acts together with other apple bHLH TFs to regulate Fe uptake by modulating the expression of the MdAHA8 gene and the activity of PM H(+) -ATPase in apple. PMID:26801352

  15. Regulation of Galactolipid Biosynthesis by Overexpression of the Rice MGD Gene Contributes to Enhanced Aluminum Tolerance in Tobacco

    PubMed Central

    Zhang, Meijuan; Deng, Xiping; Yin, Lina; Qi, Lingyun; Wang, Xinyue; Wang, Shiwen; Li, Hongbing

    2016-01-01

    Membrane lipid alterations affect Al tolerance in plants, but little is known about the regulation of membrane lipid metabolism in response to Al stress. Transgenic tobacco (Nicotiana tabacum) overexpressing rice monogalactosyldiacylglycerol (MGDG) synthase (OsMGD) gene and wild-type tobacco plants were exposed to AlCl3, and the impact of Al toxicity on root growth, Al accumulation, plasma membrane integrity, lipid peroxidation and membrane lipid composition were investigated. Compared with the wild type, the transgenic plants exhibited rapid regrowth of roots after removal of Al and less damage to membrane integrity and lipid peroxidation under Al stress, meanwhile, the Al accumulation showed no difference between wild-type and transgenic plants. Lipid analysis showed that Al treatment dramatically decreased the content of MGDG and the ratio of MGDG to digalactosyldiacylglycerol (DGDG) in wild-type plants, while it was unchanged in transgenic plants. The stable of MGDG level and the ratio of MGDG/DGDG contribute to maintain the membrane stability and permeability. Moreover, Al caused a significant increase in phospholipids in wild-type plants, resulting in a high proportion of phospholipids and low proportion of galactolipids, but these proportions were unaffected in transgenic plants. The high proportion of phospholipids could contribute to a higher rate of Al3+ binding in the membrane and thereby leads to more membrane perturbation and damage. These results show that the regulation of galactolipid biosynthesis could play an important role in maintaining membrane structure and function under Al stress. PMID:27066017

  16. Regulation of Galactolipid Biosynthesis by Overexpression of the Rice MGD Gene Contributes to Enhanced Aluminum Tolerance in Tobacco.

    PubMed

    Zhang, Meijuan; Deng, Xiping; Yin, Lina; Qi, Lingyun; Wang, Xinyue; Wang, Shiwen; Li, Hongbing

    2016-01-01

    Membrane lipid alterations affect Al tolerance in plants, but little is known about the regulation of membrane lipid metabolism in response to Al stress. Transgenic tobacco (Nicotiana tabacum) overexpressing rice monogalactosyldiacylglycerol (MGDG) synthase (OsMGD) gene and wild-type tobacco plants were exposed to AlCl3, and the impact of Al toxicity on root growth, Al accumulation, plasma membrane integrity, lipid peroxidation and membrane lipid composition were investigated. Compared with the wild type, the transgenic plants exhibited rapid regrowth of roots after removal of Al and less damage to membrane integrity and lipid peroxidation under Al stress, meanwhile, the Al accumulation showed no difference between wild-type and transgenic plants. Lipid analysis showed that Al treatment dramatically decreased the content of MGDG and the ratio of MGDG to digalactosyldiacylglycerol (DGDG) in wild-type plants, while it was unchanged in transgenic plants. The stable of MGDG level and the ratio of MGDG/DGDG contribute to maintain the membrane stability and permeability. Moreover, Al caused a significant increase in phospholipids in wild-type plants, resulting in a high proportion of phospholipids and low proportion of galactolipids, but these proportions were unaffected in transgenic plants. The high proportion of phospholipids could contribute to a higher rate of Al(3+) binding in the membrane and thereby leads to more membrane perturbation and damage. These results show that the regulation of galactolipid biosynthesis could play an important role in maintaining membrane structure and function under Al stress. PMID:27066017

  17. Silicon Promotes Adventitious Shoot Regeneration and Enhances Salinity Tolerance of Ajuga multiflora Bunge by Altering Activity of Antioxidant Enzyme

    PubMed Central

    Sivanesan, Iyyakkannu; Jeong, Byoung Ryong

    2014-01-01

    We investigated the effect of Si concentration on shoot regeneration and salinity tolerance of Ajuga multiflora. Addition of Si to the shoot induction medium significantly increased the frequency of shoot induction. The average number of shoots regenerated per explant decreased on the medium containing NaCl alone, while there was less decrease when the shoot induction medium was supplemented with both NaCl and Si. The shoot induction percentage increased linearly with increasing concentration of Si in the NaCl containing medium. Addition of Si to the shoot induction medium significantly increased SOD, POD, APX, and CAT activity in regenerated shoot buds as compared with the control. The inclusion of Si to the NaCl containing medium significantly increased the SOD activity in leaves and roots, while it decreased POD, APX, and CAT activity in both organs. Scanning electron microscopic analysis showed that there are no distinct differences in the structure of stomata between the control and Si-treated plants. However, NaCl treatment significantly affected the structure and number of stomata as compared to the control. Wavelength dispersive X-ray analysis confirmed the high Si deposition in trichomes of plants grown in the Si containing medium but not in plants grown in the medium without Si. PMID:24526904

  18. Enhanced drought-tolerance in the homoploid hybrid species Pinus densata: implication for its habitat divergence from two progenitors.

    PubMed

    Ma, Fei; Zhao, Changming; Milne, Richard; Ji, Mingfei; Chen, Litong; Liu, Jianquan

    2010-01-01

    The homoploid hybrid species Pinus densata is restricted to alpine habitats that exceed the altitude range of its two parental species, Pinus tabulaeformis and Pinus yunnanensis. Alpine habitats usually generate cold-induced water stress in plants. To understand the ecological differentiation between these three species, we examined their physiological responses to drought stress. Potted seedlings of three species were subjected to low, mild, moderate and severe water stress in an automatic-controlled glasshouse. Fifteen indicators of fitness were measured for each species in each treatment, and most of these decreased as drought increased. Pinus densata exhibited higher fitness than both parental species in terms of total dry mass production (TDM) and long-term water use efficiency (WUE(L)) across all treatments; several other ecophysiological traits were also extreme but not across every treatment, and not always in the highest stress treatment. These results indicate that extreme characters that have become well fixed in P. densata, confer a faster seedling growth rate and more efficient water use, which in turn should confer increased drought tolerance. These traits of P. densata likely promoted its ecological separation from its parental species and facilitated its successful colonization and establishment in high-altitude habitats. PMID:19804499

  19. A Sweetpotato Geranylgeranyl Pyrophosphate Synthase Gene, IbGGPS, Increases Carotenoid Content and Enhances Osmotic Stress Tolerance in Arabidopsis thaliana.

    PubMed

    Chen, Wei; He, Shaozhen; Liu, Degao; Patil, Gunvant B; Zhai, Hong; Wang, Feibing; Stephenson, Troy J; Wang, Yannan; Wang, Bing; Valliyodan, Babu; Nguyen, Henry T; Liu, Qingchang

    2015-01-01

    Sweetpotato highly produces carotenoids in storage roots. In this study, a cDNA encoding geranylgeranyl phyrophosphate synthase (GGPS), named IbGGPS, was isolated from sweetpotato storage roots. Green fluorescent protein (GFP) was fused to the C-terminus of IbGGPS to obtain an IbGGPS-GFP fusion protein that was transiently expressed in both epidermal cells of onion and leaves of tobacco. Confocal microscopic analysis determined that the IbGGPS-GFP protein was localized to specific areas of the plasma membrane of onion and chloroplasts in tobacco leaves. The coding region of IbGGPS was cloned into a binary vector under the control of 35S promoter and then transformed into Arabidopsis thaliana to obtain transgenic plants. High performance liquid chromatography (HPLC) analysis showed a significant increase of total carotenoids in transgenic plants. The seeds of transgenic and wild-type plants were germinated on an agar medium supplemented with polyethylene glycol (PEG). Transgenic seedlings grew significantly longer roots than wild-type ones did. Further enzymatic analysis showed an increased activity of superoxide dismutase (SOD) in transgenic seedlings. In addition, the level of malondialdehyde (MDA) was reduced in transgenics. qRT-PCR analysis showed altered expressions of several genes involved in the carotenoid biosynthesis in transgenic plants. These data results indicate that IbGGPS is involved in the biosynthesis of carotenoids in sweetpotato storage roots and likely associated with tolerance to osmotic stress. PMID:26376432

  20. A Sweetpotato Geranylgeranyl Pyrophosphate Synthase Gene, IbGGPS, Increases Carotenoid Content and Enhances Osmotic Stress Tolerance in Arabidopsis thaliana

    PubMed Central

    Liu, Degao; Patil, Gunvant B.; Zhai, Hong; Wang, Feibing; Stephenson, Troy J.; Wang, Yannan; Wang, Bing; Valliyodan, Babu; Nguyen, Henry T.; Liu, Qingchang

    2015-01-01

    Sweetpotato highly produces carotenoids in storage roots. In this study, a cDNA encoding geranylgeranyl phyrophosphate synthase (GGPS), named IbGGPS, was isolated from sweetpotato storage roots. Green fluorescent protein (GFP) was fused to the C-terminus of IbGGPS to obtain an IbGGPS-GFP fusion protein that was transiently expressed in both epidermal cells of onion and leaves of tobacco. Confocal microscopic analysis determined that the IbGGPS-GFP protein was localized to specific areas of the plasma membrane of onion and chloroplasts in tobacco leaves. The coding region of IbGGPS was cloned into a binary vector under the control of 35S promoter and then transformed into Arabidopsis thaliana to obtain transgenic plants. High performance liquid chromatography (HPLC) analysis showed a significant increase of total carotenoids in transgenic plants. The seeds of transgenic and wild-type plants were germinated on an agar medium supplemented with polyethylene glycol (PEG). Transgenic seedlings grew significantly longer roots than wild-type ones did. Further enzymatic analysis showed an increased activity of superoxide dismutase (SOD) in transgenic seedlings. In addition, the level of malondialdehyde (MDA) was reduced in transgenics. qRT-PCR analysis showed altered expressions of several genes involved in the carotenoid biosynthesis in transgenic plants. These data results indicate that IbGGPS is involved in the biosynthesis of carotenoids in sweetpotato storage roots and likely associated with tolerance to osmotic stress. PMID:26376432

  1. Enhanced hydrogen oxidation activity and H2S tolerance of Ni-infiltrated ceria solid oxide fuel cell anodes

    NASA Astrophysics Data System (ADS)

    Mirfakhraei, Behzad; Paulson, Scott; Thangadurai, Venkataraman; Birss, Viola

    2013-12-01

    The effect of Ni infiltration into porous Gd-doped ceria (GDC) anodes on their H2 oxidation performance, with and without added 10 ppm H2S, is reported here. Porous GDC anodes (ca. 10 μm thick) were deposited on yttria stabilized zirconia (YSZ) supports and then infiltrated with catalytic amounts of a Ni nitrate solution, followed by electrochemical testing in a 3-electrode half-cell setup at 500-800 °C. Infiltration of 3 wt.% Ni into the porous GDC anode lowered the polarization resistance by up to 85%, affecting mainly the low frequency impedance arc. When exposed to 10 ppm H2S, the Ni-infiltrated anodes exhibited a ca. 5 times higher tolerance toward sulfur poisoning compared to GDC anodes alone, also showing excellent long-term stability in 10 ppm H2S. In the presence of H2S, it is proposed that Ni, likely distributed as a nanophase, helps to maintain a clean GDC surface at the Ni/GDC interface at which the H2 oxidation reaction takes place. In turn, the GDC will readily supply oxygen anions to the adjacent Ni surfaces, thus helping to remove adsorbed sulfur.

  2. Serum Malondialdehyde Concentration and Glutathione Peroxidase Activity in a Longitudinal Study of Gestational Diabetes

    PubMed Central

    Miranda, María; Muriach, María; Romero, Francisco J.; Villar, Vincent M.

    2016-01-01

    Aims The main goal of this study was to evaluate the presence of oxidative damage and to quantify its level in gestational diabetes. Methods Thirty-six healthy women and thirty-six women with gestational diabetes were studied in the three trimesters of pregnancy regarding their levels of oxidative stress markers. These women were diagnosed with diabetes in the second trimester of pregnancy. Blood glucose levels after 100g glucose tolerance test were higher than 190, 165 or 145 mg/dl, 1, 2 or 3 hours after glucose intake. Results The group of women with gestational diabetes had higher serum malondialdehyde levels, with significant differences between groups in the first and second trimester. The mean values of serum glutathione peroxidase activity in the diabetic women were significantly lower in the first trimester. In the group of women with gestational diabetes there was a negative linear correlation between serum malondialdehyde concentration and glutathione peroxidase activity in the second and third trimester. Conclusions In this observational and longitudinal study in pregnant women, the alterations attributable to oxidative stress were present before the biochemical detection of the HbA1c increase. Usual recommendations once GD is detected (adequate metabolic control, as well as any other normally proposed to these patients) lowered the concentration of malondialdehyde at the end of pregnancy to the same levels of the healthy controls. Serum glutathione peroxidase activity in women with gestational diabetes increased during the gestational period. PMID:27228087

  3. Peroxidase-induced wilting in transgenic tobacco plants

    SciTech Connect

    Lagrimini, L.M.; Bradford, S. ); Rothstein, S. )

    1990-01-01

    Peroxidases are a family of isoenzymes found in all higher plants. However, little is known concerning their role in growth, development or response to stress. Plant peroxidases are heme-containing monomeric glycoproteins that utilize either H{sub 2}O{sub 2} or O{sub 2} to oxidize a wide variety of molecules. To obtain more information on possible in planta functions of peroxidases, the authors have used a cDNA clone for the primary isoenzyme form of peroxidase to synthesize high levels of this enzyme in transgenic plants. They were able to obtain Nicotiana tabacum and N. sylvestris transformed plants with peroxidase activity that is 10-fold higher than in wild-type plants by introducing a chimeric gene composed of the cauliflower mosaic virus 35S promoter and the tobacco anionic peroxidase cDNA. The elevated peroxidase activity was a result of increased levels of two anionic peroxidases in N. tabacum, which apparently differ in post-translational modification. Transformed plants of both species have the unique phenotype of chronic severe wilting through loss of turgor in leaves, which was initiated a the time of flowering. The peroxidase-induced wilting was shown not to be an effect of diminished water uptake through the roots, decreased conductance of water through the xylem, or increased water loss through the leaf surface of stomata. Possible explanations for the loss of turgor, and the significance of these types of experiments in studying isoenzyme families, are discussed.

  4. Sequence analysis and homology modeling of peroxidase from Medicago sativa

    PubMed Central

    Hooda, Vinita; Gundala, Prasada babu; Chinthala, Paramageetham

    2012-01-01

    Plant peroxidases are one of the most extensively studied group of enzymes which find applications in the environment, health, pharmaceutical, chemical and biotechnological processes. Class III secretary peroxidase from alfalfa (Medicago sativa) has been characterized using bioinformatics approach Physiochemical properties and topology of alfalfa peroxidase were compared with that of soybean and horseradish peroxidase, two most popular commercially available peroxidase preparations. Lower value of instability index as predicted by ProtParam and presence of extra disulphide linkages as predicted by Cys_REC suggested alfalfa peroxidase to be more stable than either of the commercial preparations. Multiple Sequence Alignment (MSA) with other functionally similar proteins revealed the presence of highly conserved catalytic residues. Three dimensional model of alfalfa peroxidase was constructed based on the crystal structure of soybean peroxidase (PDB Id: 1FHF A) by homology modelling approach. The model was checked for stereo chemical quality by PROCHECH, VERIFY 3D, WHAT IF, ERRAT, 3D MATCH AND ProSA servers. The best model was selected, energy minimized and used to analyze structure function relationship with substrate hydrogen peroxide by Autodock 4.0. The enzyme substrate complex was viewed with Swiss PDB viewer and one residue ASP43 was found to stabilize the interaction by hydrogen bonds. The results of the study may be a guiding point for further investigations on alfalfa peroxidase. PMID:23275690

  5. Structure of a mitochondrial cytochrome c conformer competent for peroxidase activity

    PubMed Central

    McClelland, Levi J.; Mou, Tung-Chung; Jeakins-Cooley, Margaret E.; Sprang, Stephen R.; Bowler, Bruce E.

    2014-01-01

    At the onset of apoptosis, the peroxidation of cardiolipin at the inner mitochondrial membrane by cytochrome c requires an open coordination site on the heme. We report a 1.45-Å resolution structure of yeast iso-1-cytochrome c with the Met80 heme ligand swung out of the heme crevice and replaced by a water molecule. This conformational change requires modest adjustments to the main chain of the heme crevice loop and is facilitated by a trimethyllysine 72-to-alanine mutation. This mutation also enhances the peroxidase activity of iso-1-cytochrome c. The structure shows a buried water channel capable of facilitating peroxide access to the active site and of moving protons produced during peroxidase activity to the protein surface. Alternate positions of the side chain of Arg38 appear to mediate opening and closing of the buried water channel. In addition, two buried water molecules can adopt alternate positions that change the network of hydrogen bonds in the buried water channel. Taken together, these observations suggest that low and high proton conductivity states may mediate peroxidase function. Comparison of yeast and mammalian cytochrome c sequences, in the context of the steric factors that permit opening of the heme crevice, suggests that higher organisms have evolved to inhibit peroxidase activity, providing a more stringent barrier to the onset of apoptosis. PMID:24760830

  6. Cytochrome c peroxidase from Methylococcus capsulatus Bath.

    PubMed

    Zahn, J A; Arciero, D M; Hooper, A B; Coats, J R; DiSpirito, A A

    1997-11-01

    A bacterial cytochrome c peroxidase was purified from the obligate methanotroph Methylococcus capsulatus Bath in either the fully oxidized or the half reduced form depending on the purification procedure. The cytochrome was a homo-dimer with a subunit mol mass of 35.8 kDa and an isoelectric point of 4.5. At physiological temperatures, the enzyme contained one high-spin, low-potential (Em7 = -254 mV) and one low-spin, high-potential (Em7 = +432 mM ) heme. The low-potential heme center exhibited a spin-state transition from the penta-coordinated, high-spin configuration to a low-spin configuration upon cooling the enzyme to cryogenic temperatures. Using M. capsulatus Bath ferrocytochrome c555 as the electron donor, the KM and Vmax for peroxide reduction were 510 +/- 100 nM and 425 +/- 22 mol ferrocytochrome c555 oxidized min-1 (mole cytochrome c peroxidase)-1, respectively. PMID:9325424

  7. Horseradish peroxidase catalyzed hydroxylations: mechanistic studies.

    PubMed

    Dordick, J S; Klibanov, A M; Marletta, M A

    1986-05-20

    The hydroxylation of phenol to hydroquinone and catechol in the presence of dihydroxyfumaric acid and oxygen catalyzed by horseradish peroxidase was studied under conditions where the product yield was high and the side reactions were minimal. The reaction is partially uncoupled with a molar ratio of dihydroxyfumaric acid consumed to hydroxylated products of 12:1. Hydrogen peroxide does not participate in the reaction as evidenced by the lack of effect of catalase and by the direct addition of hydrogen peroxide. Conversely, superoxide and hydroxyl radicals are involved as their scavengers are potent inhibitors. Experiments were all consistent with the involvement of compound III (oxygenated ferrous complex) of peroxidase in the reaction. Compound III is stable in the presence of phenol alone but decomposes rapidly in the presence of both phenol and dihydroxyfumaric acid with the concomitant formation of product. Therefore, phenol and dihydroxyfumaric acid must be present with compound III in order for the hydroxylation reaction to occur. A mechanism consistent with the experimental results is proposed. PMID:3718931

  8. Enhancing Sulfur Tolerance of Ni-Based Cermet Anodes of Solid Oxide Fuel Cells by Ytterbium-Doped Barium Cerate Infiltration.

    PubMed

    Li, Meng; Hua, Bin; Luo, Jing-Li; Jiang, San Ping; Pu, Jian; Chi, Bo; Li, Jian

    2016-04-27

    Conventional anode materials for solid oxide fuel cells (SOFCs) are Ni-based cermets, which are highly susceptible to deactivation by contaminants in hydrocarbon fuels. Hydrogen sulfide is one of the commonly existed contaminants in readily available natural gas and gasification product gases of pyrolysis of biomasses. Development of sulfur tolerant anode materials is thus one of the critical challenges for commercial viability and practical application of SOFC technologies. Here we report a viable approach to enhance substantially the sulfur poisoning resistance of a Ni-gadolinia-doped ceria (Ni-GDC) anode through impregnation of proton conducting perovskite BaCe0.9Yb0.1O3-δ (BCYb). The impregnation of BCYb nanoparticles improves the electrochemical performance of the Ni-GDC anode in both H2 and H2S containing fuels. Moreover, more importantly, the enhanced stability is observed in 500 ppm of H2S/H2. The SEM and XPS analysis indicate that the infiltrated BCYb fine particles inhibit the adsorption of sulfur and facilitate sulfur removal from active sites, thus preventing the detrimental interaction between sulfur and Ni-GDC and the formation of cerium sulfide. The preliminary results of the cell with the BCYb+Ni-GDC anode in methane fuel containing 5000 ppm of H2S show the promising potential of the BCYb infiltration approach in the development of highly active and stable Ni-GDC-based anodes fed with hydrocarbon fuels containing a high concentration of sulfur compounds. PMID:27052726

  9. Searching in sequences of Leymus BAC clones for genes controlling salt tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many species of Thinopyrum and Leymus are known to be highly salt tolerant. Salinity tolerance in diploid Thinopyrum elongatum, thus all polyploid Thinopyrum species too, is controlled by genes on different chromosomes. Some candidate genes, including genes for peroxidase precursor, for salinity t...

  10. Enhanced salt stress tolerance of rice plants expressing a vacuolar H+-ATPase subunit c1 (SaVHAc1) gene from the halophyte grass Spartina alterniflora Löisel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The physiological role of a vacuolar ATPase subunit c1 (SaVHAc1) from a halophyte grass Spartina alterniflora was studied through its expression in rice. The SaVHAc1– expressing plants showed enhanced tolerance to salt stress than the wild-type plants, mainly through adjustments in early stage and p...

  11. DCA1 Acts as a Transcriptional Co-activator of DST and Contributes to Drought and Salt Tolerance in Rice.

    PubMed

    Cui, Long-Gang; Shan, Jun-Xiang; Shi, Min; Gao, Ji-Ping; Lin, Hong-Xuan

    2015-10-01

    Natural disasters, including drought and salt stress, seriously threaten food security. In previous work we cloned a key zinc finger transcription factor gene, Drought and Salt Tolerance (DST), a negative regulator of drought and salt tolerance that controls stomatal aperture in rice. However, the exact mechanism by which DST regulates the expression of target genes remains unknown. In the present study, we demonstrated that DST Co-activator 1 (DCA1), a previously unknown CHY zinc finger protein, acts as an interacting co-activator of DST. DST was found to physically interact with itself and to form a heterologous tetramer with DCA1. This transcriptional complex appears to regulate the expression of peroxidase 24 precursor (Prx 24), a gene encoding an H2O2 scavenger that is more highly expressed in guard cells. Downregulation of DCA1 significantly enhanced drought and salt tolerance in rice, and overexpression of DCA1 increased sensitivity to stress treatment. These phenotypes were mainly influenced by DCA1 and negatively regulated stomatal closure through the direct modulation of genes associated with H2O2 homeostasis. Our findings establish a framework for plant drought and salt stress tolerance through the DCA1-DST-Prx24 pathway. Moreover, due to the evolutionary and functional conservation of DCA1 and DST in plants, engineering of this pathway has the potential to improve tolerance to abiotic stress in other important crop species. PMID:26496194

  12. Physiological and biochemical parameters for evaluation and clustering of rice cultivars differing in salt tolerance at seedling stage.

    PubMed

    Chunthaburee, Sumitahnun; Dongsansuk, Anoma; Sanitchon, Jirawat; Pattanagul, Wattana; Theerakulpisut, Piyada

    2016-07-01

    Salinity tolerance levels and physiological changes were evaluated for twelve rice cultivars, including four white rice and eight black glutinous rice cultivars, during their seedling stage in response to salinity stress at 100 mM NaCl. All the rice cultivars evaluated showed an apparent decrease in growth characteristics and chlorophyll acc