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141.
M. A. Nogueira U. Nehls R. Hampp K. Poralla E. J. B. N. Cardoso 《Plant and Soil》2007,298(1-2):273-284
Excess manganese (Mn) in soil is toxic to crops, but in some situations arbuscular mycorrhizal fungi (AMF) alleviate the toxic
effects of Mn. Besides the increased phosphorus (P) uptake, mycorrhiza may affect the balance between Mn-reducing and Mn-oxidizing
microorganisms in the mycorrhizosphere and affect the level of extractable Mn in soil. The aim of this work was to compare
mycorrhizal and non-mycorrhizal plants that received extra P in relation to alleviation of Mn toxicity and the balance between
Mn-oxidizing and Mn-reducing bacteria in the mycorrhizosphere. A clayey soil containing 508 mg kg−1 of extractable Mn was fertilized with 30 mg kg−1 (P1) or 45 mg kg−1 (P2) of soluble P. Soybean (Glycine max L. Merrill, cv. IAC 8-2) plants at P1 level were non-inoculated (CP1) or inoculated with either Glomus etunicatum (GeP1) or G. macrocarpum (GmP1), while plants at P2 level were left non-inoculated (CP2). Plants were grown in a greenhouse and harvested after 80 days.
In the mycorrhizosphere of the GmP1 and GeP1 plants a shift from Mn-oxidizing to Mn-reducing bacteria coincided with higher
soil extractability of Mn and Fe. However, the occurrence of Mn-oxidizing/reducing bacteria in the (mycor)rhizosphere was
unrelated to Mn toxicity in plants. Using 16S rDNA sequence homologies, the Mn-reducing isolates were consistent with the
genus Streptomyces. The Mn-oxidizers were homologous with the genera Arthrobacter, Variovorax and Ralstonia. While CP1 plants showed Mn toxicity throughout the whole growth period, CP2 plants never did, in spite of having Fe and
Mn shoot concentrations as high as in CP1 plants. Mycorrhizal plants showed Mn toxicity symptoms early in the growth period
that were no longer visible in later growth stages. The shoot P concentration was almost twice as high in mycorrhizal plants
compared with CP1 and CP2 plants. The shoot Mn and Fe concentrations and contents were lower in GmP1 and GeP1 plants compared
with the CP2 treatment, even though levels of extractable metals increased in the soil when plants were mycorrhizal. This
suggests that mycorrhiza protected its host plant from excessive uptake of Mn and Fe. In addition, higher tissue P concentrations
may have facilitated internal detoxification of Mn in mycorrhizal plants. The exact mechanisms acting on alleviation of Mn
toxicity in mycorrhizal plants should be further investigated. 相似文献
142.
Hassinen VH Tervahauta AI Halimaa P Plessl M Peräniemi S Schat H Aarts MG Servomaa K Kärenlampi SO 《Planta》2007,225(4):977-989
Several populations with different metal tolerance, uptake and root-to-shoot transport are known for the metal hyperaccumulator
plant Thlaspi caerulescens. In this study, genes differentially expressed under various Zn exposures were identified from the shoots of two T. caerulescens accessions (calaminous and non-calaminous) using fluorescent differential display RT-PCR. cDNA fragments from 16 Zn-responsive
genes, including those encoding metallothionein (MT) type 2 and type 3, MRP-like transporter, pectin methylesterase (PME)
and Ole e 1-like gene as well as several unknown genes, were eventually isolated. The full-length MT2 and MT3 sequences differ from those previously isolated from other Thlaspi accessions, possibly representing new alleles or isoforms. Besides the differential expression in Zn exposures, the gene
expression was dependent on the accession. Thlaspi homologues of ClpP protease and MRP transporter were induced at high Zn concentrations. MT2 and PME were expressed at higher
levels in the calaminous accession. The MTs and MRP transporter expressed in transgenic yeasts were capable of conferring
Cu and Cd tolerance, whereas the Ole e 1-like gene enhanced toxicity to these metals. The MTs increased yeast intracellular
Cd content. As no significant differences were found between Arabidopsis and Thlaspi MTs, they apparently do not differ in their capacity to bind metals. However, the higher levels of MT2 in the calaminous
accession may contribute to the Zn-adapted phenotype. 相似文献
143.
Masaru Shibata Takayuki Konno Ryo Akaike Yong Xu Renfang Shen Jian Feng Ma 《Plant and Soil》2007,290(1-2):201-208
EDTA-assisted phytoextraction of lead (Pb) has been developed, but concerns have arisen due to the possibility of leaching
of both Pb and EDTA to ground water caused by uncontrolled release. We developed five types of controlled-release EDTA (polymer-coated
EDTA) by coating the EDTA with a polyolefin polymer. A test of the release rate showed that the duration for the release of
75% of total EDTA ranged from 3 to 210 days. A pot experiment was conducted to compare the effect of these polymer-coated
EDTA and non-coated EDTA on the concentrations of Pb and EDTA in soil solution, and Pb accumulation in sorghum (Sorghum bicolor L. cv. EARLY SUMAC) in a Pb-contaminated soil. One of the polymer-coated EDTAs, C-EDTA-4, with a release period of 80 days
proved to be the best in decreasing Pb and EDTA concentrations in soil solution, and increasing Pb accumulation in sorghum
shoots compared to the direct application of EDTA. Our results suggest that polymer-coated EDTA has a potential for phytoextraction
of Pb with a reduced environmental risk. 相似文献
144.
CopA, a thermophilic ATPase from Archaeoglobus fulgidus, drives the outward movement of Cu+ across the cell membrane. Millimolar concentration of Cys dramatically increases (≅ 800%) the activity of CopA and other PIB-type ATPases (Escherichia coli ZntA and Arabidopsis thaliana HMA2). The high affinity of CopA for metal (≅ 1 μM) together with the low Cu+-Cys KD (< 10− 10M) suggested a multifaceted interaction of Cys with CopA, perhaps acting as a substitute for the Cu+ chaperone protein present in vivo. To explain the activation by the amino acid and further understand the mechanism of metal delivery to transport ATPases, Cys effects on the turnover and partial reactions of CopA were studied. 2-20 mM Cys accelerates enzyme turnover with little effect on CopA affinity for Cu+, suggesting a metal independent activation. Furthermore, Cys activates the p-nitrophenyl phosphatase activity of CopA, even though this activity is metal independent. Cys accelerates enzyme phosphorylation and the forward dephosphorylation rates yielding higher steady state phosphoenzyme levels. The faster dephosphorylation would explain the higher enzyme turnover in the presence of Cys. The amino acid has no significant effect on low affinity ATP Km suggesting no changes in the E1 ↔ E2 equilibrium. Characterization of Cu+ transport into sealed vesicles indicates that Cys acts on the cytoplasmic side of the enzyme. However, the Cys activation of truncated CopA lacking the N-terminal metal binding domain (N-MBD) indicates that activation by Cys is independent of the regulatory N-MBD. These results suggest that Cys is a non-essential activator of CopA, interacting with the cytoplasmic side of the enzyme while this is in an E1 form. Interestingly, these effects also point out that Cu+ can reach the cytoplasmic opening of the access path into the transmembrane transport sites either as a free metal or a Cu+-Cys complex. 相似文献
145.
Banci L Bertini I Chasapis CT Rosato A Tenori L 《Biochemical and biophysical research communications》2007,364(3):645-649
Yeast Ccc2 is a P-type ATPase responsible for transport of copper(I) from the cytosol to the trans-Golgi network. It possesses a soluble cytosolic N-terminal region containing two copper(I)-binding domains. Homologous eukaryotic copper-transporting ATPases have from one to six domains. We have expressed a fragment encompassing residues 1-150 of Ccc2, which corresponds to the two domains, and found that the second domain was substantially less structured than the first. The first domain could bind copper(I) and interact with the partner protein Atx1 at variance with the second. Similar results are found in ATPases from other organisms and may represent a general feature, whose biochemical implications are not yet fully appreciated. 相似文献
146.
In order to evaluate hydrocarbon inputs to Crater Lake from anthropogenic and natural sources, samples of water, aerosol,
surface slick and sediment were collected and analyzed by gas chromatography-mass spectrometry (GC-MS) for determination of
their aliphatic and aromatic hydrocarbon concentrations and compositions. Results show that hydrocarbons originate from both
natural (terrestrial plant waxes and algae) and anthropogenic (petroleum use) sources and are entering the lake through direct
input and atmospheric transport. The concentrations of petroleum hydrocarbons range from low to undetectable. The distributions
and abundances of n-alkanes, polycyclic aromatic hydrocarbons (PAH) and unresolved complex mixture (UCM) from petroleum are similar for all surface
slick sampling sites. The estimated levels of PAH in surface slicks range from 7–9 ng/m2 which are low. Transport of petroleum-derived hydrocarbons from the lake surface has resulted in their presence in some sediments,
particularly near the boat operations mooring (total petroleum HC = 1440 μg/kg, dry wt. compared to naturally derived n-alkanes, 240 μg/kg, dry wt.). The presence of biomarkers such as the tricyclic terpanes, hopanes and steranes in shallow
sediments further confirms petroleum input from boat traffic. In the deep lake sediments, petroleum hydrocarbon concentrations
were very low (16 μg/kg, dry wt.). Very low concentrations of PAH were detected in shallow sediments (17–40 μg/kg at 5 m depth
near the boat operations) and deep sediments (3–15 μg/kg at 580 m depth). The individual PAH concentrations in sediments (μg/kg
or ppb range) are at least three orders of magnitude less than reported threshold effects levels (mg/kg or ppm range, test
amphipod Hyalella azteca). Therefore, no adverse effects are expected to occur in benthic biota exposed to these sediments. Boating activities are leaving a detectable level of petroleum in surface waters and lake sediments but these concentrations are very low. 相似文献
147.
Christophe Faulmann Stéphane Dorbes Kane Jacob Gábor Molnár José Antonio Real 《Inorganica chimica acta》2007,360(13):3870-3878
A new compound of formula [Fe(qsal)2][Ni(dmit)2] (1) has been synthesised, structurally and magnetically characterised (qsalH = N-(8-quinolyl)salicylaldimine, dmit2− = 1,3-dithiol-2-thione-4,5-dithiolato). Its structural features and its magnetic behaviour were compared with those of [Fe(qsal)2]-based complexes, and more particularly [Fe(qsal)2][Ni(dmit)2] · 2CH3CN. 相似文献
148.
Elisabete Oliveira Laura Valencia Emilia Bértolo Carlos Lodeiro 《Inorganica chimica acta》2007,360(8):2734-2743
A new scorpionate system (L) containing an emissive anthracene pendant arm, derived of O1,O7-bis(2-formylphenyl)-1,4,7-trioxaheptane and tren, has been synthesized and characterized. The sensing capability of L towards a range of metal ions has been studied. Protonation and complexation studies, using UV-Vis and fluorescent emission measurements, have been performed with alkaline and alkaline earth metal ions (M = Na(I), K(I), Li(I), Ca(II), Mg(II)), as well as transition and post-transition metal ions (M = Cr(III), Cu(II) and Zn(II), Cd(II), Hg(II) and Al(III)). An increase in the fluorescence emission (CHEF effect) was observed in methanol and in methanol/water mixtures in the presence of Cd(II) (5.0-fold), Zn(II) (4.5-fold), Cr(III) (2.0-fold) and Al(III) (1.8-fold); these results suggest a notable sensing ability of this new N3O4 ligand for these metals; these experiments were also performed in the presence of large amounts of alkaline and alkaline earth metal ions. 相似文献
149.
Sehye Kim 《Inorganica chimica acta》2007,360(6):1870-1874
A new organic-inorganic hybrid solid with 3-D framework, [Mn(DMF)3]2[Re6Se8(CN)6] (1), has been synthesized and transformed to [H][Mn(salen)]3[Re6Se8(CN)6] (2) by a ligand exchange. Hexarhenium chalcocyanide clusters are closest packed in cubic symmetry for 1 and rhombohedral symmetry for 2. The manganese complexes in the interstitial sites are three-coordinated to the rhenium cluster in 1 and two-coordinated in 2. 相似文献
150.
Synthesis and characterization of metal ion imprinted nano-porous polymer for the selective recognition of copper 总被引:1,自引:0,他引:1
Baghel A Boopathi M Singh B Pandey P Mahato TH Gutch PK Sekhar K 《Biosensors & bioelectronics》2007,22(12):3326-3334
Selective recognition of metal ions utilizing metal ion-imprinted polymers (MIIPs) received much importance in diverse fields owing to their high selectivity for the target metal ions. In the present study, a copper ion imprinted polymer was synthesized without an additional complexing ligand or complex with a broad aim to avoid the conventional extra metal ion complexing ligand during the synthesis of MIIP. The complete removal of the copper metal ion from the MIIP was confirmed by AAS and SEM–EDX. SEM image of the MIIP exhibited nano-patterns and it was also found to be entirely different from that of non-imprinted polymer and polymer with copper metal ions. BET surface area analysis revealed more surface area (47.96 m2/g) for the Cu(II)-MIIP than non-imprinted control polymer (41.43 m2/g). TGA result of polymer with copper metal ion indicated more char yield (18.41%) when compared to non-imprinted control polymer (8.3%) and Cu(II)-MIIP (less than 1%). FTIR study confirmed the complexation between Cu(II)-MIIP and Cu(II) metal ion through carbonyl oxygen of acryl amide. The Cu(II)-MIIP exhibited an imprinting efficiency of 2.0 and it was showing 8% interference from a mixture of Zn, Ni and Co ions. A potentiometric ion selective electrode devised with Cu(II)-MIIP showed more potential response for Cu(II) ion than that was fabricated from non-imprinted polymer. 相似文献