Hongyun Peng

Toxicity and deficiency of copper in Elsholtzia splendens affect photosynthesis biophysics, pigments and metal accumulation.

Elsholtzia splendens is a copper-tolerant plant species growing on copper deposits in China. Spatially and spectrally resolved kinetics of in vivo absorbance and chlorophyll fluorescence in mesophyll of E. splendens were used to investigate the copper-induced stress from deficiency and toxicity as well as the acclimation to excess copper stress. The plants were cultivated in nutrient solutions containing either Fe(III)-EDTA or Fe(III)-EDDHA. Copper toxicity affected light-acclimated electron flow much stronger than nonphotochemical quenching (NPQ) or dark-acclimated photochemical efficiency of PSIIRC (Fv/Fm). It also changed spectrally resolved Chl fluorescence kinetics, in particular by strengthening the short-wavelength (<700 nm) part of NPQ altering light harvesting complex II (LHCII) aggregation. Copper toxicity reduced iron accumulation, decreased Chls and carotenoids in leaves. During acclimation to copper toxicity, leaf copper decreased but leaf iron increased, with photosynthetic activity and pigments recovering to normal levels. Copper tolerance in E. splendens was inducible; acclimation seems be related to homeostasis of copper and iron in E. splendens. Copper deficiency appeared at 10 mg copper per kg leaf DW, leading to reduced growth and decreased photosynthetic parameters (F0, Fv/Fm, ΦPSII). The importance of these results for evaluating responses of phytoremediation plants to stress in their environment is discussed.

Caffeic acid product from the highly copper-tolerant plant Elsholtzia splendens post-phytoremediation: its extraction, purification, and identification.

In the current study, caffeic acid was an important metabolite in the highly copper-tolerant plant Elsholtzia splendens. Preparation and purification of caffeic acid were performed on the dried biomass of the plants by means of sonication/ethanol extraction, followed by purification using a macroporous resin (D101 type) column and silica gel chromatography. The faint-yellow caffeic acid product was yielded with a purity of 98.46%, and it was chemically identified from spectra of Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR)/carbon nuclear magnetic resonance (13C NMR), and electrospray ionization mass spectrometry (ESI-MS). Caffeic acid is a possible product from the post-harvest processing of Elsholtzia splendens biomass.

Improved cadmium uptake and accumulation in the hyperaccumulator Sedum alfredii： the impact of citric acid and tartaric acid

The elucidation of a natural strategy for metal hyperaccumulation enables the rational design of technologies for the clean-up of metal-contaminated soils. Organic acid has been suggested to be involved in toxic metallic element tolerance, translocation, and accumulation in plants. The impact of exogenous organic acids on cadmium (Cd) uptake and translocation in the zinc (Zn)/Cd co-hyperaccumulator Sedum alfredii was investigated in the present study. By the addition of organic acids, short-term (2 h) root uptake of 109Cd increased significantly, and higher 109Cd contents in roots and shoots were noted 24 h after uptake, when compared to controls. About 85% of the 109Cd taken up was distributed to the shoots in plants with citric acid (CA) treatments, as compared with 75% within controls. No such effect was observed for tartaric acid (TA). Reduced growth under Cd stress was significantly alleviated by low CA. Long-term application of the two organic acids both resulted in elevated Cd in plants, but the effects varied with exposure time and levels. The results imply that CA may be involved in the processes of Cd uptake, translocation and tolerance in S. alfredii, whereas the impact of TA is mainly on the root uptake of Cd.

PHYTOEXTRACTION OF COPPER FROM CONTAMINATED SOIL BY ELSHOLTZIA SPLENDENS AS AFFECTED BY EDTA, CITRIC ACID, AND COMPOST

Abstract Phytoextraction of copper (Cu) from contaminated soils greatly depends on the metal bioavailability in the soils and metal uptake ability of the plant. In this study, the effects of chelators [ethylenediamine tetraacetic acid (EDTA), citric acid (CA)] and compost amendments on Cu phytoextraction potential by a tolerant and accumulating plant species (E. splendens) were examined in two types of contaminated soils, i.e., the mined soil from Cu-mined area (MS) and a paddy soil polluted by Cu refining (PS). The results showed that EDTA application at 2.5–5.0 mmol kg− 1 increased phytoextraction of Cu by four- and eight-fold from both MS and PS, respectively, which is mainly attributed to increased H2O extractable Cu in the soil. The Cu amount extracted by the shoots of E. splendens reached 800–1000 μg Cu plant− 1 from the MS and 400–700 μg Cu plant − 1 from the PS at EDTA application rates of 2.5 ∼5.0 mmol kg− 1. The application of CA at 5.0 mmol kg− 1 had minimal effects on Cu extractability in both soils and slightly decreased Cu extraction efficiency by E. splendens. Plant biomass production was enhanced by CA at 0.25 mmol L− 1 in nutrient solution, but inhibited by CA at 5.0 mmol kg− 1 in both MS and PS. Increasing the compost rate significantly decreased H2O extractable Cu in the MS, but raised H2O-extractable Cu in the PS, which resulted mainly from the reduced exchangeable Cu in the MS and the increased exchangeable and organic fractions of Cu in the PS by compost. At high compost rate (5%), the shoots of E. splendens extracted 3.6-fold higher Cu from the PS than from the MS. These results indicate that, among the soil amendments, efficiency of Cu phytoextraction is enhanced mostly by 2.5–5.0 mmol kg− 1 EDTA, followed by 5% (w:w) compost, whereas < 5.0 mmol kg− 1CA has minimal effects on Cu phytoextraction by E. splendens in the PS. As for the MS, only 2.5–5.0 mmol kg− 1EDTA can elevate the efficiency of Cu, while 5% compost amendment and <5.0 mmol kg− 1 CA application have no marked effects on Cu phytoextraction by E. splendens.

Copper phytoavailability and uptake by Elsholtzia splendens from contaminated soil as affected by soil amendments.

Abstract Pot and field experiments were conducted to evaluate bioavailability of Cu in contaminated paddy soil (PS) and phytoremediation potential by Elsholtzia splendens as affected by soil amendments. The results from pot experiment showed that organic manure (M) applied to the PS not only remarkably raised the H2O exchangeable Cu, which were mainly due to the increased exchangeable and organic fractions of Cu in the PS by M, but also stimulated plant growth and Cu accumulation in E. splendens. At M application rate of 5.0%, shoot Cu concentration in the plant increased by four times grown on the PS, so as to the elevated shoot Cu accumulation by three times as compared to the control. In the field trial, soil amendments by M and furnace slag (F), and soil preparations like soil capping (S) and soil discing (D) were performed in the PS. Soil capping and discing considerably declined total Cu in the PS. Application of M solely or together with F enhanced plant growth and increased H2O exchangeable Cu levels in the soil. The increased extractability of Cu in the rhizosphere of E. splendens was noted, which may have mainly attributed to the rhizospheric acidification and chelation by dissolved organic matter (DOM), thus resulting in elevating Cu uptake and accumulation by E. splendens. Amendments with organic manure plus furnace slag (MF) to the PS caused the highest exactable Cu with saturated H2O in the rhizospheric soil of E. splendens after they were grown for 170 days in the PS, thus achieving 1.74 kg Cu ha− 1 removal from the contaminated soil by the whole plant of E. splendens at one season, which is higher than those of the other soil treatments. The results indicated that application of organic manure at a proper rate could enhance Cu bioavailability and increase effectiveness of Cu phytoextraction from the contaminated soil by the metal-tolerant and accumulating plant species (E. splendens).

Responses of Antioxidant Enzyme System to Copper Toxicity and Copper Detoxification in the Leaves of Elsholtzia splendens

ABSTRACT Solution culture experiments were conducted to study physiological responses to copper (Cu) toxicity and Cu detoxification involved in the antioxidant enzyme system in the leaves of Elsholtzia splendens (E. splendens). Compared with the control, 500 μM Cu considerably reduced oxidizing force and Apase activity in roots, as well as net photosynthetic rate and transpiration rate in leaves, but greatly stimulated lipid peroxidation and proline accumulation. In contrast, 50 μM Cu elevated oxidizing force and Apase activity in roots, chlorophyll content, net photosynthetic rate, and transpiration rate in leaves, and elevated proline content but decreased lipid peroxidation in the plant compared to with the control. Furthermore, at 500 μM Cu, heavily damaged organelles were found in the leaf cell of E. splendens, while at 50 μM Cu organelles were not markedly affected. These results indicate that greater oxidative stresses were induced at 500 μM Cu than at 50 μM Cu. Plants responded to Cu-induced oxidative stresses by modulating antioxidant enzymes and substrates. Compared with the control, the activities of superoxide dismutases (SOD), catalase (CAT), glutathione peroxidase (GPX), and ascorbate peroxidase (APX) in the leaves of the plant increased pronouncedly at 500 μM Cu, while at 50 μM Cu, GPX activity decreased notably and the activities of APX, SOD, and CAT changed only slightly. Copper also altered glutathione (GSH) content and glutathione reductase (GR) activity. At 50 μM Cu, both GSH content and GR activity in the leaves of the plant increased dramatically; however, at 500 μM Cu, GR activity increased but GSH content changed only slightly compared with the control. These results suggest that some adaptive physiology responses to Cu toxicity and the antioxidant enzyme system are involved in Cu detoxification in leaves of E. splendens, but at 500 μM Cu the limited activities of the antioxidant enzyme system in leaves of E. splendens make it difficult to counteract the greater oxidation stresses in vivo.

Interpolymer specific interaction in blends of poly(styrene-co-alkyl acrylate-co-4-vinylpyridine) and poly(styrene-co-alkyl acrylate-co-acrylic acid)

Abstract The interpolymer specific interaction of proton donating polymer (PDP) and proton accepting polymer (PAP) in toluene was studied by viscometry coupled with light scattering. The viscometric experiment results show that the stronger the interpolymer interaction is, the higher the viscosity of PDP/PAP blend solution than the weight-average of both components at high concentration, in contrast to lower viscosity at low concentration. Based on the relationship of viscosity enhancement factor with polymer level in solution, a new polymer–polymer interaction parameter k a to estimate interpolymer interaction was developed. The effects of functional groups content and acrylate unit on interpolymer interaction were studied with this parameter combined with light scattering. The results show that interpolymer interaction ability increases with the functional group and long chain alkyl acrylate content. With the increase in side chain length of acrylate unit, enhancement in the interpolymer specific interaction can be realized.

Endothelium-dependent and -independent vasorelaxant actions and mechanisms induced by total flavonoids of Elsholtzia splendens in rat aortas.

Elsholtzia splendens (ES) is, rich in flavonoids, used to repair copper contaminated soil in China, which has been reported to benefit cardiovascular systems as folk medicine. However, few direct evidences have been found to clarify the vasorelaxation effect of total flavonoids of ES (TFES). The vasoactive effect of TFES and its underlying mechanisms in rat thoracic aortas were investigated using the organ bath system. TFES (5-200mg/L) caused a concentration-dependent vasorelaxation in endothelium-intact rings, which was not abolished but significantly reduced by the removal of endothelium. The nitric oxide synthase (NOS) inhibitor N(ω)-nitro-l-arginine methyl ester (100μM) and the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,2-α]quinoxalin-1-one (30μM) significantly blocked the endothelium-dependent vasorelaxation of TFES. Meanwhile, NOS activity in endothelium-intact aortas was concentration-dependently elevated by TFES. However, indomethacin (10μM) did not affect TFES-induced vasorelaxation. Endothelium-independent vasorelaxation of TFES was significantly attenuated by KATP channel blocker glibenclamide. The accumulative Ca(2+)-induced contraction in endothelium-denuded aortic rings primed with KCl or phenylephrine was markedly weakened by TFES. These results revealed that the NOS/NO/cGMP pathway is likely involved in the endothelium-dependent vasorelaxation induced by TFES, while activating KATP channel, inhibiting intracellular Ca(2+) release, blocking Ca(2+) channels and decreasing Ca(2+) influx into vascular smooth muscle cells might contribute to the endothelium-independent vasorelaxation conferred by TFES.

Extraction and isolation of the salidroside-type metabolite from zinc (Zn) and cadmium (Cd) hyperaccumulator Sedum alfredii Hance

The active metabolite in the post-harvested biomass of zinc (Zn) and cadmium (Cd) hyperaccumulator Sedum alfredii Hance from phytoextraction is of great interest in China. The current study demonstrates that a salidroside-type metabolite can be yielded from the Zn/Cd hyperaccumulator S. alfredii biomass by means of sonication/ethanol extraction and macroporous resin column (AB-8 type) isolation. The concentrations of Zn and Cd in the salidroside-type metabolite were below the limitation of the national standards.

n-DIOCTADECYL FUMARATE–VINYL ACETATE COPOLYMER: SYNTHESIS, CHARACTERIZATION AND APPLICATION AS FLOW IMPROVER FOR OILS

ABSTRACT Monomer n-dioctadecyl fumarate (DOF), and copolymers (C18FVA) of DOF with vinyl acetate were synthesized. Monomer and copolymers were characterized by IR, 1H-NMR, VPO and DSC. Due to the special structure of DOF, only copolymers containing 45.9%–97.8% (mol) DOF were obtained. The crystalline CH2 numbers on polymer side chain χ were calculated from enthalpy determined by DSC, and it was found that χ slightly decreased with increasing vinyl acetate content. C18FVA can be used as flow improver for viscous oil and residual oil, and the more the crystalline CH2 number on the side chains, the better lattice match between copolymer and wax crystal structure of oils.