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1.
Ca2+ has been proposed to mediate inhibition of root elongation. However, exogenous Ca2+ at 10 or 20 millimolar, applied directly to the root cap, significantly stimulated root elongation in pea (Pisum sativum L.) and corn (Zea mays L.) seedlings. Furthermore, Ca2+ at 1 to 20 millimolar, applied unilaterally to the caps of Alaska pea roots, caused root curvature away from the Ca2+ source, which was caused by an acceleration of elongation growth on the convex side (Ca2+ side) of the roots. Roots of an agravitropic pea mutant, ageotropum, responded to a greater extent. Roots of Merit and Silver Queen corn also responded to Ca2+ in similar ways but required a higher Ca2+ concentration than that of pea roots. Roots of all other cultivars tested (additional four cultivars of pea and one of corn) curved away from the unilateral Ca2+ source as well. The Ca2+-stimulated curvature was substantially enhanced by light. A Ca2+ ionophore, A23187, at 20 micromolar or abscisic acid at 0.1 to 100 micromolar partially substituted for the light effect and enhanced the Ca2+-stimulated curvature in the dark. Unilateral application of Ca2+ to the elongation zone of intact roots or to the cut end of detipped roots caused either no curvature or very slight curvature toward the Ca2+. Thus, Ca2+ action on root elongation differs depending on its site of application. The stimulatory action of Ca2+ may involve an elevation of cytoplasmic Ca2+ in root cap cells and may participate in root tropisms. 相似文献
2.
重金属铜、锌、镉复合胁迫对麻疯树幼苗生理生化的影响 总被引:2,自引:0,他引:2
该研究以Cu~(2+)、Zn~(2+)、Cd~(2+)单一胁迫为对照,探讨不同浓度的Cu~(2+)、Zn~(2+)、Cd~(2+)复合胁迫对麻疯树幼苗生理生化指标的影响。结果表明:随着Cu~(2+)、Zn~(2+)、Cd~(2+)浓度的增加,麻疯树幼苗叶片中的蛋白质(Pro)、丙二醛(MDA)含量均逐渐增加,其叶片叶绿素含量随着Zn~(2+)胁迫浓度的增加呈现出先降后升的趋势,在中等浓度(100 mg·L-1)的Zn~(2+)胁迫时含量最低、随着Cu~(2+)胁迫浓度的增加叶绿素含量先升高后降低,在Cu~(2+)浓度为200 mg·L-1时含量最高,达到1 200 mg·g-1FW; Cd~(2+)胁迫对叶绿素含量和根系活力无明显影响。根系活力在Zn~(2+)浓度为100 mg·L~(-1)时最强,随着Cu~(2+)浓度的增加而减弱。低浓度的Cu~(2+)、Zn~(2+)、Cd~(2+)对过氧化物酶活性和可溶性糖含量都具有促进作用。Cu~(2+)、Zn~(2+)、Cd~(2+)复合胁迫时对可溶性蛋白、叶绿素和丙二醛含量均无明显影响,随着复合胁迫时浓度的增加,可溶性糖含量和根系活力先增后减。这表明麻疯树对三种重金属的胁迫具有一定的抗性,过高浓度的胁迫会影响麻疯树幼苗生理生化的一些指标,但是麻疯树可以通过自身的防御系统使伤害降到最小。此外,重金属复合胁迫可以在一定程度上减轻单一胁迫对麻疯树幼苗造成的毒害作用。 相似文献
3.
Characterization of the Effects of Divalent Cations on the Coupled Activities of the H-ATPase in Tonoplast Vesicles 总被引:4,自引:2,他引:2
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The substrate requirement of the H+-ATPase in purified corn root tonoplast vesicles was investigated. The coupled activities, ATP hydrolysis and proton pumping, were simultaneously supported only by Mg2+ or Mn2+. The presence of Ca2+ or Ba2+ did not significantly affect the coupled activities. The addition of Cd2+, Co2+, Cu2+, and Zn2+ inhibited both the hydrolysis of Mg-ATP and the proton transport. However, the inhibition of proton pumping was more pronounced. Based on equilibrium analysis, both ATP-complexed and free forms of these cations were inhibitory. Inhibition of the hydrolysis of Mg-ATP could be correlated to the concentrations of the ATP-complex of Zn. On the other hand, the free Cu2+ and Co2+ were effective in inhibiting hydrolysis. For proton pumping, the ATP complexes of Co2+, Cu2+, and Zn2+ were effective inhibitors. However, this inhibition could be further modulated by free Co2+, Cu2+, and Zn2+. While the equilibrium concentrations of Cd-ATP and free Cd2+ were not estimated, the total concentration of this cation needed to inhibit the coupled activities of the H+-ATPase was found to be in the range of 10 to 100 micromolars. The presence of free divalent cations also affected the structure of the lipid phase in tonoplast membrane as demonstrated by the changes of emission intensity and polarization of incorporated 1,6-diphenyl-1,3,5-hexatriene. The differential inhibition caused by these cations could be interpreted by interactions with the protogenic domain of the membrane as previously proposed in “indirect-link” mechanism. 相似文献
4.
The absorption characteristics of Cd2+ by 10- to 12-day-old soybean plants (Glycine max cv Williams) were investigated with respect to influence of Cd concentration on adsorption to root surfaces, root absorption, transport kinetics and interaction with the nutrient cations Cu2+, Fe2+, Mn2+, and Zn2+. The fraction of nonexchangeable Cd bound to roots remained relatively constant at 20 to 25% of the absorbed fraction at solution concentration of 0.0025 to 0.5 micromolar, and increased to 45% at solution concentration in excess of 0.5 micromolar. The exchangeable fraction represented 1.4 to 32% of the absorbed fraction, and was concentration dependent. Using dinitrophenol as a metabolic inhibitor, the `metabolically absorbed' fraction was shown to represent 75 to 80% of the absorbed fraction at concentration less than 0.5 micromolar, and decreased to 55% at 5 micromolar. At comparatively low Cd concentrations, 0.0025 to micromolar 0.3, root absorption exhibited two isotherms with K2 values of 0.08 and 1.2 micromolar. Root absorption and transfer from root to shoot of Cd2+ was inhibited by Cu2+, Fe2+, Mn2+, and Zn2+. Analyses of kinetic interaction of these nutrient cations with Cd2+ indicated that Cu2+, Fe2+, Zn2+, and possibly Mn2+ inhibited Cd absorption competitively suggesting an involvement of a common transport site or process. 相似文献
5.
I. R. Grin P. G. Konorovsky G. A. Nevinsky D. O. Zharkov 《Biochemistry. Biokhimii?a》2009,74(11):1253-1259
Prokaryotic enzymes formamidopyrimidine-DNA glycosylase (Fpg) and endonuclease VIII (Nei) and their eukaryotic homologs NEIL1,
NEIL2, and NEIL3 define the Fpg family of DNA glycosylases, which initiate the process of repair of oxidized DNA bases. The
repair of oxidative DNA lesions is known to be impaired in vivo in the presence of ions of some heavy metals. We have studied the effect of salts of several alkaline earth and transition
metals on the activity of Fpg-family DNA glycosylases in the reaction of excision of 5,6-dihydrouracil, a typical DNA oxidation
product. The reaction catalyzed by NEIL1 was characterized by values K
m = 150 nM and k
cat = 1.2 min−1, which were in the range of these constants for excision of other damaged bases by this enzyme. NEIL1 was inhibited by Al3+, Ni2+, Co2+, Cd2+, Cu2+, Zn2+, and Fe2+ in Tris-HCl buffer and by Cd2+, Zn2+, Cu2+, and Fe2+ in potassium phosphate buffer. Fpg and Nei, the prokaryotic homologs of NEIL1, were inhibited by the same metal ions as NEIL1.
The values of I50 for NEIL1 inhibition were 7 μM for Cd2+, 16 μM for Zn2+, and 400 μM for Cu2+. The inhibition of NEIL1 by Cd2+, Zn2+, and Cu2+ was at least partly due to the formation of metal-DNA complexes. In the case of Cd2+ and Cu2+, which preferentially bind to DNA bases rather than phosphates, the presence of metal ions caused the enzyme to lose the
ability for preferential binding to damaged DNA. Therefore, the inhibition of NEIL1 activity in removal of oxidative lesions
by heavy metal ions may be a reason for their comutagenicity under oxidative stress. 相似文献
6.
Correlation between Calmodulin Activity and Gravitropic Sensitivity in Primary Roots of Maize 总被引:5,自引:4,他引:1
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Charles L. Stinemetz Konrad M. Kuzmanoff Michael L. Evans Harry W. Jarrett 《Plant physiology》1987,84(4):1337-1342
Recent evidence indicates a role for calcium and calmodulin in the gravitropic response of primary roots of maize (Zea mays, L.). We examined this possibility by testing the relationship between calmodulin activity and gravitropic sensitivity in roots of the maize cultivars Merit and B73 × Missouri 17. Roots of the Merit cultivar require light to be gravitropically competent. The gravitropic response of the Missouri cultivar is independent of light. The occurrence of calmodulin in primary roots of these maize cultivars was tested by affinity gel chromatography followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis with bovine brain calmodulin as standard. The distribution of calmodulin activity was measured using both the phosphodiesterase and NAD kinase assays for calmodulin. These assays were performed on whole tissue segments, crude extracts, and purified extracts. In light-grown seedlings of the Merit cultivar or in either dark- or light-grown seedlings of the Missouri cultivar, calmodulin activity per millimeter of root tissue was about 4-fold higher in the apical millimeter than in the subtending 3 millimeters. Calmodulin activity was very low in the apical millimeter of roots of dark-grown (gravitropically nonresponsive) seedlings of the Merit cultivar. Upon illumination, the calmodulin activity in the apical millimeter increased to a level comparable to that of light-grown seedlings and the roots became gravitropically competent. The time course of the development of gravitropic sensitivity following illumination paralleled the time course of the increase in calmodulin activity in the apical millimeter of the root. The results are consistent with the suggestion that calmodulin plays an important role in the gravitropic response of roots. 相似文献
7.
Regulation of the mitochondrial oxidation-reduction state in intact hepatocytes by calcium ions 总被引:1,自引:0,他引:1
The mitochondrial NADH:NAD ratio of isolated intact liver cells incubated in calcium-free Hanks solution, in the endogenous state or with lactate, alanine, α-ketoglutarate, glutamate, fumarate, malate, or albumin-bound palmitate, was elevated by 1 mM CaCl2. The chloride salts of Ba+2, Cd+2, Cu+2, Mn+2, Sr+2, Zn+2, Al+3, Ce+3 and La+3 caused no such change. In contrast, calcium decreased the mitochondrial NADH:NAD ratio of hepatocytes incubated with succinate. Calcium did not affect the NADH:NAD ratio in the liver cell cytosol or the energy charge. The calcium-induced elevation in the mitochondrial NADH:NAD ratio was reversed by the uncoupler 1799. These observations demonstrate a specific effect of calcium ions in the regulation of the mitochondrial oxidation-reduction state in intact liver cells. 相似文献
8.
《Journal of enzyme inhibition and medicinal chemistry》2013,28(1):68-73
Glutathione reductase (GR; E.C. 1.6.4.2) is a flavoprotein that catalyzes the NADPH-dependent reduction of oxidized glutathione (GSSG). In this study we tested the effects of Al3+, Ba2+, Ca2+, Li+, Mn2+, Mo6+, Cd2+, Ni2+, and Zn2+ on purified bovine liver GR. In a range of 10?μM–10?mM concentrations, Al3+, Ba2+, Li+, Mn2+, and Mo6+, and Ca2+ at 5?μM–1.25?mM, had no effect on bovine liver GR. Cadmium (Cd2+), nickel (Ni2+), and zinc (Zn2+) showed inhibitory effects on this enzyme. The obtained IC50 values of Cd2+, Ni2+, and Zn2+ were 0.08, 0.8, and 1?mM, respectively. Cd2+ inhibition was non-competitive with respect to both GSSG (KiGSSG 0.221?±?0.02?mM) and NADPH (KiNADPH 0.113?±?0.008?mM). Ni2+ inhibition was non-competitive with respect to GSSG (KiGSSG 0.313?±?0.01?mM) and uncompetitive with respect to NADPH (KiNADPH 0.932?±?0.03?mM). The effect of Zn2+ on GR activity was consistent with a non-competitive inhibition pattern when the varied substrates were GSSG (KiGSSG 0.320?±?0.018?mM) and NADPH (KiNADPH 0.761?±?0.04?mM), respectively. 相似文献
9.
重金属递进胁迫对黑麦草初期生长的影响 总被引:14,自引:0,他引:14
通过研究Cu2+、Zn2+、Cd2+与Pb2+胁迫对黑麦草初期生长的影响,结果表明:4种重金属对种子发芽率抑制效应相对较小,尤其Cu2+与Zn2+的抑制作用最小。高浓度Cu2+、Cd2+胁迫对株高、根系长度、地上生物量的抑制作用相对较大,尤其Cu2+对根系生长的抑制效应最大,在300 mg·L-1下,与对照相比,根长最高下降了 85.48%。高浓度Cd2+胁迫显著降低了叶绿素含量,在300 mg·L-1时比对照降低了45.51%;与对照相比,Cu2+与Zn2+所有处理都增加了叶绿素含量。从递进胁迫进程看,一些重金属对某一生长指标的影响往往表现在低浓度具有促进作用,而高浓度又存在明显的抑制效应。 相似文献
10.
In liver homogenate the biosynthesis ofN-acetylneuraminic acid usingN-acetylglucosamine as precursor can be followed stepwise by applying different chromatographic procedures. In this cell-free system 16 metal ions (Zn2+, Mn2+, La3+, Co2+, Cu2+, Hg2+, VO
3
–
, Pb2+, Ce3+, Cd2+, Fe2+, Fe3+, Al3+, Sn2+, Cs+ and Li+) and the selenium compounds, selenium(IV) oxide and sodium selenite, have been checked with respect to their ability to influence a single or possible several steps of the biosynthesis ofN-acetylneuraminic acid. It could be shown that the following enzymes are sensitive to these metal ions (usually applied at a concentration of 1 mmoll–1):N-acetylglucosamine kinase (inhibited by Zn2+ and vandate), UDP-N-acetylglucosamine-2-epimerase (inhibited by zn2+, Co2+, Cu2+, Hg2+, VO
3
–
, Pb2+, Cd2+, Fe3+, Cs+, Li+, selenium(IV) oxide and selenite), andN-acetylmannosamine kinase (inhibited by Zn2+, Cu2+, Cd2+, and Co2+). Dose dependent measurements have shown that Zn2+, Cu2+ and selenite are more efficient inhibitors of UDP-N-acetylglucosamine-2-epimerase than vanadate. As for theN-acetylmannosamine kinase inhibition, a decreasing inhibitory effect exists in the following order Zn2+, Cd2+, Co2+ and Cu2+. In contrast, La3+, Al3+ and Mn2+ (1 mmoll–1) did not interfere with the biosynthesis ofN-acetylneuraminic acid. Thus, the conclusion that the inhibitory effect of the metal ions investigated cannot be regarded as simply unspecific is justified.Dedicated to Professor Theodor Günther on the occasion of his 60th birthday 相似文献
11.
Kazuki Oka Hiroshi Maeda Shoichi Ikeda 《International journal of biological macromolecules》1983,5(6):342-346
The effects of eight divalent metal ions on fully neutralized poly(S-carboxyethyl-l-cysteine) have been studied by means of circular dichroism. Four ionic species (Cd2+, Cu2+, Zn2+ and Ni2+) effectively induce the β-form, while the other four species (Co2+, Ba2+, Ca2+ and Mg2+) are not effective. Specifically, Mg(ClO4)2 is ineffective, even at 1.86 m. The effect of Cu2+ ions on the polypeptide conformation is significant at pH values other than in the neural range. Comparison of the present results with previous ones from the lower side chain homologue, poly(S-carboxymethyl-l-cysteine), shows that Cd2+ and Zn2+ ions are more effetive but Co2+ ions are much less effective in the polypeptide studied here. Random coils of poly(S-carboxyethyl-l-cysteine) are more soluble while the β-form is less soluble compared with the respective conformations of the lower side-chain homologue. 相似文献
12.
Kazuki Oka Hiroshi Maeda Shoichi Ikeda 《International journal of biological macromolecules》1983,5(6)
The effects of eight divalent metal ions on fully neutralized poly(S-carboxyethyl-l-cysteine) have been studied by means of circular dichroism. Four ionic species (Cd2+, Cu2+, Zn2+ and Ni2+) effectively induce the β-form, while the other four species (Co2+, Ba2+, Ca2+ and Mg2+) are not effective. Specifically, Mg(ClO4)2 is ineffective, even at 1.86 m. The effect of Cu2+ ions on the polypeptide conformation is significant at pH values other than in the neural range. Comparison of the present results with previous ones from the lower side chain homologue, poly(S-carboxymethyl-l-cysteine), shows that Cd2+ and Zn2+ ions are more effetive but Co2+ ions are much less effective in the polypeptide studied here. Random coils of poly(S-carboxyethyl-l-cysteine) are more soluble while the β-form is less soluble compared with the respective conformations of the lower side-chain homologue. 相似文献
13.
Rong Pan Lixiang Cao Haiwei Huang Renduo Zhang Yu Mo 《Applied microbiology and biotechnology》2010,88(4):997-1005
In this study, dried and humid fruiting bodies of Tremella fuciformis and Auricularia polytricha were examined as cost-effective biosorbents in treatment of heavy metals (Cd2+, Cu2+, Pb2+, and Zn2+) in aqueous solution. The humid T. fuciformis showed the highest capacity to adsorb the four metals in the multi-metal solutions. The Pb2+ adsorption rates were 85.5%, 97.8%, 84.8%, and 91.0% by dried T. fuciformis, humid T. fuciformis, dried A. polytricha, and humid A. polytricha, respectively. The adsorption amount of Pb2+ by dried and humid T. fuciformis in Cd2+ + Pb2+, Cu2+ + Pb2+, Pb2+ + Zn2+, Cd2+ + Cu2+ + Pb2+, and Cd2+ + Zn2+ + Pb2+ solutions were not lower than that in Pb2+ solutions. The results suggested that in humid T. fuciformis, Cd2+, Cu2+, and Zn2+ promoted the Pb2+ adsorption by the biomass. In the multi-metal solutions of Cd2+ + Cu2+ + Pb2+ + Zn2+, the adsorption amount and rates of the metals by all the test biosorbents were in the order of Pb2+ > Cu2+ > Zn2+ > Cd2+. Compared with the pseudo first-order model, the pseudo second-order model described the adsorption kinetics much better,
indicating a two-step biosorption process. The present study confirmed that fruiting bodies of the jelly fungi should be useful
for the treatment of wastewater containing Cd2+, Cu2+, Pb2+, and Zn2+. 相似文献
14.
Effects of multivalent cations on cell wall-associated Acid phosphatase activity 总被引:2,自引:2,他引:0
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Primary cell walls, free from cytoplasmic contamination were prepared from corn (Zea mays L.) roots and potato (Solanum tuberosum) tubers. After EDTA treatment, the bound acid phosphatase activities were measured in the presence of various multivalent cations. Under the conditions of minimized Donnan effect and at pH 4.2, the bound enzyme activity of potato tuber cell walls (PCW) was stimulated by Cu2+, Mg2+, Zn2+, and Mn2+; unaffected by Ba2+, Cd2+, and Pb2+; and inhibited by Al3+. The bound acid phosphatase of PCW was stimulated by a low concentration but inhibited by a higher concentration of Hg2+. On the other hand, in the case of corn root cell walls (CCW), only inhibition of the bound acid phosphatase by Al3+ and Hg2+ was observed. Kinetic analyses revealed that PCW acid phosphatase exhibited a negative cooperativity under all employed experimental conditions except in the presence of Mg2+. In contrast, CCW acid phosphatase showed no cooperative behavior. The presence of Ca2+ significantly reduced the effects of Hg2+ or Al3+, but not Mg2+, to the bound cell wall acid phosphatases. The salt solubilized (free) acid phosphatases from both PCW and CCW were not affected by the presence of tested cations except for Hg2+ or Al3+ which caused a Ca2+-insensitive inhibition of the enzymes. The induced stimulation or inhibition of bound acid phosphatases was quantitatively related to cation binding in the cell wall structure. 相似文献
15.
《Phytochemistry》1996,41(1):105-109
In the early growth phase of Sesamum indicum cv. PB-1, the decrease in fresh and dry mass was higher with 1.0 mM Cd2+ than with the same level of Pb2+ and Cu2+. Recovery from the metal stress was considerable in the root fresh weight and almost completely in the root dry weight when 10.0 mM (1.9 EC), calcium chloride was supplied to the growing seedlings along with the metal salts in various combinations. Accumulation of Pb2+, Cd2+ and Cu2+ was differential to the metals and the plant parts when supplied without or with 10.0 mM calcium chloride. The order of endogenous metal accumulation was Cu2+Cd2+Pb2+ and roots accumulated more metal than the leaves in the absence, as well as in the presence, of calcium chloride. Calcium chloride could recover loss of in vivo NRA in roots caused by either of the metal combinations, whereas the salt could recover the loss in leaf NRA caused only by Pb2+Cd2+ (1.0 mM each). Response of root and leaf NRA was on the other hand, different when the enzyme was assayed directly using an in vitro assay method, and the salt accelerated the loss in enzyme activity drastically. The organic-N content of root and leaf was, however, increased significantly (p < 0.001) with calcium chloride alone and with the metals supplied in various combinations. Our data indicate that instead of a high endogenous accumulation of Cu2+, Cd2+ and Pb2+ in roots and leaves the metal toxicity is recovered to a great extent in the presence of 10.0 mM calcium chloride in the root environment regarding growth and nitrate reduction of the roots and leaves of young sesame seedlings. 相似文献
16.
Jingli Yang Yucheng Wang Guifeng Liu Chuanping Yang Chenghao Li 《Molecular biology reports》2011,38(3):1567-1574
A metallothionein-like gene, ThMT3, encoding a type 3 metallothionein, was isolated from a Tamarix hispida leaf cDNA library. Expression analysis revealed that mRNA of ThMT3 was upregulated by high salinity as well as by heavy metal ions, and that ThMT3 was predominantly expressed in the leaf. Transgenic yeast (Saccharomyces cerevisiae) expressing ThMT3 showed increased tolerance to Cd2+, Zn2+, Cu2+, and NaCl stress. Transgenic yeast also accumulated more Cd2+, Zn2+, and NaCl, but not Cu2+. Analysis of the expression of four genes (GLR1, GTT2, GSH1, and YCF1) that aid in transporting heavy metal (Cd2+) from the cytoplasm to the vacuole demonstrated that none of these genes were induced under Cd2+, Zn2+, Cu2+, and NaCl stress in ThMT3-transgenic yeast. H2O2 levels in transgenic yeast under such stress conditions were less than half those in control yeast under the same conditions.
Three antioxidant genes (SOD1, CAT1, and GPX1) were specifically expressed under Cd2+, Zn2+, Cu2+, and NaCl stress in the transgenic yeast. Cd2+, Zn2+, and Cu2+ increased the expression levels of SOD1, CAT1, and GPX1, respectively, whereas NaCl induced the expression of SOD1 and GPX1. 相似文献
17.
Effect of heavy metal ions on growth and biochemical characteristics of photosynthesis of barley and maize seedlings 总被引:1,自引:0,他引:1
The effects of Cu2+, Zn2+, Cd2+ and Pb2+ on growth and the biochemical characteristics of photosynthesis were more expressed in barley (Hordeum vulgare L.) than in maize (Zea mays L.) seedlings. The barley and maize seedlings exhibited retardation in shoot and root growth after exposure of Cu2+, Cd2+ and Pb2+. The Zn2+ions practically did not influence these characteristics. The total protein content of barley and maize roots declined with an increase in heavy metal ion concentrations. The protein content of barley shoots was only slighly decreased with an increase in heavy metal ion concentrations, but the protein content in maize shoots was increased under the same conditions. The chlorophyll content was decreased in barley shoots and increased in maize. The ribulose-l,5-bisphosphate carboxylase (RuBPC, EC 4.1.1.39) and phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) activities were decreased drastically by Cu2+, Cd2+ and Pb2+ in thein vivo experiments. The tested heavy metal ions affect photosynthesis probably mainly by inhibition of these key carboxylating enzymes: this mechanism was studied in thein vitro experiments. 相似文献
18.
A fluorescence and absorption chemosensor (SAAT) based on 5-(hydroxymethyl)-salicylaldehyde (SA) and o-aminothiophenol (AT) was designed and synthesized. SAAT in DMSO–HEPES (20.0 mM, v/v, 1:99, pH = 7.0) solution shows a highly selective and sensitive absorption and an ‘on–off’ fluorescence response to Cu2+ ions in aqueous solutions over all other competitive metal ions including Na+, Ag+, Ba2+, Ca2+, Cd2+, Mg2+, Zn2+, Cr3+, Al3+, Hg2+, K+, Mn2+, Ni2+, Sr2+, Tb3+ and Co2+. SAAT exhibits ratiometric absorption sensing ability for Cu2+ ions. Importantly, SAAT also can sense Cu2+ ions using fluorescence quenching, the fluorescence intensity of SAAT showed a good linear relationship with Cu2+ concentration, and the detection limit of Cu2+ was 0.34 μM. The results of Job's plot, Benesi–Hildebrand plot, mass spectra, and density functional theory calculations confirmed that the selective absorption and fluorescence response were attributed to the formation of a 1:1 complex between SAAT and Cu2+. SAAT in test film could identify Cu2+ in water samples using the intuitive fluorescence colour change under a UV lamp. SAAT has great application value as a selective and sensitive chemosensor to discriminate and detect Cu2+ ions. 相似文献
19.
The nature of the interaction between polyacrylalc ion and several divalent cations, such as Cu2+, Mn2+, Zn2+, Ba2+ and Mg2+, was investigated using Raman spectroscopy. A specific Raman band characteristic of a carboxyl group is shifted upon addition of Cu2+. Zn2+ and Mn2+ to partially neutralized poly(acrylic acid). On the other hand. no frequency shift of the specific Raman band is observed on addition of Mg2+ and Ba2+*, though the intensity of the specific Raman band decreases with concentration of MgCl2. It is concluded from these Raman data that the interaction between polyacrylatc ion and Cu2+. Zn2+ or Mn2+ includes a specific interaction with bond formation, whereas in the case of Mg2+ and Ba2+, the electrostatic interaction is dominant. 相似文献
20.
Role of Organic Acids in Sunflower Tolerance to Heavy Metals 总被引:3,自引:0,他引:3
Exposure of Helianthus annuus L. seedlings to Al3+, Cd2+ or Zn2+ resulted in a marked decrease of fresh and dry masses of the shoots and the roots. The increase of Al3+, Cd2+ or Zn2+ uptake was accompanied by a significant decrease of nitrate, phosphorus and K+ uptake. There was a significant increase of malic and citric acid contents in the shoots and roots of heavy metal-treated
seedlings whereas the change in fumaric acid was insignificant. Al3+ and Zn2+ alone stimulated excretion of malic and citric acids to the rhizosphere. Addition of high concentrations of malic or citric
acid alleviate to some extent the inhibitory effect of Al3+ and Zn2+ on plant growth.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献