Induction of non-protein thiols and phytochelatins by cadmium in Eichhornia crassipes

Abstract

Impact of root Cd concentration on production of cysteine, non-protein thiols (NP-SH), glutathione (GSH), reduced glutathione (GSSG), and phytochelatins (PCs) in Eichhornia crassipes exposed to different dilutions of brass and electroplating industry effluent (25%, 50%, and 75%), and synthetic metal solutions of Cd alone (1, 2.5, and 3.5?ppm) and with Cr (1?ppm Cd + 1?ppm Cr, 2.5?ppm Cd + 3?ppm Cr, and 3.5?ppm Cd + 4?ppm Cr) was assessed in a 45?days study. Different treatments were used to understand and compare differential antioxidant defense response of plant under practical drainage (effluent) and experimental synthetic solutions. The production of NP-SH and cysteine was maximum under 2.5?ppm Cd + 3?ppm Cr treatments i.e., 1.78?µmol/g fw and 288?nmol/g fw, respectively. The content of GSH declined whereas that of GSSG increased progressively with exposure duration in all treatments. HPLC chromatograms revealed that the concentrations of PC2, PC3, and PC4 (248, 250, and 288?nmol-SH equiv.g^?1 fw, respectively) were maximum under 1?ppm Cd, 1?ppm Cd + 1?ppm Cr, and 2.5?ppm Cd + 3?ppm Cr treatments, respectively. PC2, PC3, and PC4 concentrations increased with Cd accumulation in the range 812–1354?µg/g dry wt, 1354–2032?µg/g dry wt and 2032–3200?µg/g dry wt, respectively. Thus, the study establishes a direct proportionality relationship between concentration/length of phytochelatins and root Cd concentrations, upto threshold limits, in E. crassipes.     

The toxicity of cadmium to barley plants as affected by complex formation with humic acid

An ‘alternating solution’ culture method was used to study the effects of chloride ions and humic acid (HA) on the uptake of cadmium by barley plants. The plants were transferred periodically between a nutrient solution and a test solution containing one of four levels of HA (0, 190, 569 or 1710 μg cm⁻³) and one of five levels of Cd (0, 0.5, 1.0, 2.5 or 5.0 μg cm⁻³) in either a 0.006M NaNO₃ or 0.006M NaCl medium. Harvest and analysis of shoots and roots was after nineteen days. The distribution of Cd in the test solutions between Cd²⁺, CdCl⁺ and HA-Cd was determined in a separate experiment by dialysis equilibrium. In the nitrate test solutions Cd uptake was clearly controlled by Cd²⁺ concentration and was therefore reduced by HA complex formation. In the absence of HA, chloride suppressed Cd uptake indicating that Cd²⁺ was the preferred species. However complex formation with Cl⁻ enhanced uptake when HA was present because of an increase in the concentration of inorganic Cd species relative to the nitrate system. The ratio root-Cd/shoot-Cd remained at about 10 across a wide range of shoot-Cd concentrations, from about 3 μg g⁻¹ (sub-toxic) up to 85 μg g⁻¹ (80% yield reduction). The ability of the barley plants to accumulate ‘non-toxic’ Cd in their roots was thus very limited. Humic acid also had no effect on Cd translocation within the plant and the root/shoot weight ratio did not vary with any treatment. At shoot-Cd concentrations in excess of 50 μg g⁻¹, K, Ca, Cu and Zn uptake was reduced, probably the result of root damage rather than a specific ion antagonism. The highest concentration of HA also lowered Fe and Zn uptake and there was a toxic effect with increasing HA concentration at Cd=0. However the lowest HA level, comparable with concentrations found in mineral soil solutions, only reduced yield (in the absence of Cd) by <5% while lowering Cd uptake across the range of Cd concentrations by 66%–25%.     

Determination and risk assessment of toxic metals in lipsticks from Europe and China

BackgroundThe presence of toxic toxic metals in lipstick can pose a health risk to many consumers of this type of cosmetics, especially for women. Thus, the aim of this study was to assess consequences attributed to dermal and oral exposure to toxic metals in lipsticks manufactured in China and Europe as determined by non-cancer and cancer risks assessment models from SCCS and USEPA, respectively.MethodThe treatment of the samples was carried out by calcination using muffle furnaces and the determination of Al, Cd and Pb were determined by inductively coupled plasma optical emission spectrometry (ICP-OES).ConcentrationsThe concentration of Cd and Pb in the study samples does not exceed the limits stablished for the FDA (00,228 mg kg⁻¹·day⁻¹ for Cd and 000,343 mg kg⁻¹·day⁻¹ for Pb, respectively) but they do not comply with the Regulation of the European Parliament, which prohibits the presence of these two metals in cosmetics. Neither European Union nor United States have established maximum levels for Al in cosmetics.ConclusionsThe cancer risk assessment of Cd and Pb metals resulted in a total cancer risk less than 1. The results of non-cancer oral risk assessment for Pb had a MoS result of 88 for China and 62 for Europe, suggesting that Pb poses a risk for the human health, especially in samples manufactured in Europe.     

Influence of culinary treatment on the concentration and on the bioavailability of cadmium,chromium, copper,and lead in seafood

BackgroundSeafood present important advantages for human nutrition, but it can also accumulate high levels of toxic and potentially toxic elements. Culinary treatments could influence seafood chemical element content and element bioavailability. In this study, the influence of culinary treatments on the total concentration and on the bioavailability of Cd, Cr, Cu and Pb in shark, shrimp, squid, oyster, and scallop was assessed.MethodsBoiling, frying, and sautéing with or without seasonings (salt, lemon juice and garlic) were evaluated. Total concentration and bioavailability of Cd, Cr, Cu and Pb in seafood after all these culinary treatments were compared with those in uncooked samples. Analytes were determined by triple-quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS). An alternative to express the results avoiding underestimated or overestimated values was proposed.ResultsThe analytes concentration in seafood without culinary treatment varied from 0.0030 μg g⁻¹ (shrimp) to 0.338 μg g⁻¹ (oyster) for Cd; 0.010 μg g⁻¹ (squid) to 0.036 μg g⁻¹ (oyster) for Cr; 0.088 μg g⁻¹ (scallop) to 8.63 μg g⁻¹ (oyster) for Cu, and < 0.005 μg g⁻¹ (shrimp, squid and oyster) to 0.020 μg g⁻¹ (shark) for Pb. Only Cd (in scallop) was influenced by culinary treatments (reduction from 37 to 53 % after boiling, frying, and sautéing). Bioavailability percentage varied from 11% (oyster) for Cd; 18% (oyster) to 41% (shark) for Cr; 6% (shark) for Cu, and 8% (oyster) for Pb. Bioavailability percentage was not influenced by culinary treatments.ConclusionCadmium concentration was reduced in scallop after some culinary treatments (reduction o 37-53% after boiling, frying, and sautéing), but bioavailability percentage was not influenced. The employed analytical method was adequate for the purpose, presenting import results for food safety assessment about the influence of culinary treatments on metals concentration and bioavailability in seafood.     

Effect of calcium on the absorption and translocation of heavy metals in excised barley roots: Multi-compartment transport box experiment

Summary The effect of Ca on the absorption and translocation of Mn, Zn and Cd in excised barley roots was studied using a multi-compartment transport box technique. A radioisotope (⁵⁴Mn,⁶⁵Zn or^115mCd)-labelled test solution was supplied to the apexes of excised roots and the distribution pattern in the roots was examined in the absence or presence of Ca. Results obtained were as follows. Addition of Ca to the test solution reduced the absorption of Mn and inhibited drastically its translocation in excised roots. With increasing concentrations of Ca in test solutions, its inhibitory effects on the absorption and translocation of Mn became severe. Similar results were observed for the absorption and translocation of Zn. Ca in the test solution decreased the absorption and inhibited drastically the translocation of Zn; as in the case of Mn, higher concentrations of Ca had severe effects on these functions. It was also evident that the addition of Ca to the test solution reduced the absorption of Cd at all levels of Cd concentration (1, 10, and 100 μM). Cd absorption decreased with increasing concentrations of Ca in the test solution. However, Ca accelerated the translocation of Cd in excised roots supplied with test solutions containing up to 10μM Cd. At 100μM Cd, addition of Ca caused a negligibly small acceleration of Cd translocation. The accelerating effect of Ca on Cd translocation, especially “xylem exudation”, decreased markedly with the addition of 2,4-dinitrophenol, but not with the addition of chloramphenicol or p-chloromercuribenzene sulphonic acid. When barley plants were supplied with only CaSO₄ during the entire growing period, that is, plants were not supplied with nutrient solution on the last day of this period, Ca had no accelerating effect on Cd translocation in excised roots.     

Physiological responses,tolerance efficiency,and phytoextraction potential of Hylotelephium spectabile (Boreau) H. Ohba under Cd stress in hydroponic condition

Abstract

A sand hydroponic experiment with different concentrations of 0, 5, 10, 20, 40?mg L^?1 Cd was used to study the growth and physiological response of Hylotelephium spectabile (Boreau) H. Ohba. and its phytoextraction potential for Cd. The results showed that total plant biomass under 5?mg L^?1 Cd treatment was slightly affected. The content of malondialdehyde (MDA) in leaf exposed to Cd was higher, and the POD and CAT activity exhibited a positive response to the low level of Cd addition (5?mg·L^?1). The photosynthesis pigments were slightly inhibited, and the ultrastructure of chloroplast remained intact after treatment with 10?mg L^?1 Cd. The maximum leaf Cd content (603?mg·kg^?1) was found in 5?mg L^?1 Cd treatment, then decreased with the Cd level increased. The maximum Cd content in the shoots far exceeds the threshold level (100?mg kg^?1) for a Cd-hyperaccumulator plant with the value of translocation factor (TF_shoot/root) for Cd reaching up to 5.62. In conclusion, H. spectabile showed normal growth and physiological response and high shoot Cd accumulation under 5?mg L^?1 Cd stress, which made it to be a good candidate for phytoextraction of low-level Cd polluted environment.     

The biosynthesis of metallothionein in rat liver and kidney after administration of cadmium

The biosynthesis of the cadmium-binding protein, metallothionein, was studied in rat liver and kidney after injection of cadmium chloride. A simplified procedure for the isolation of metallothionein from liver and kidney tissues was devised. It was found that the concentration of a subcutaneously injected dose of 30 μmoles of ¹⁰⁹CdCl₂/kg in the liver reached the maximum within 36 h. Thereafter, a slow decrease in the concentration of the isotope was noted during the 3 week period. In the kidney, the isotope was taken up in two phases. During the first phase the uptake was faster and lasted for about 4 days. The second phase of ¹⁰⁹Cd accumulation showed a slower increase in the concentration of the isotope. In both liver and kidney tissues 75–80% of the ¹⁰⁹Cd was associated with metallothionein. Amino acid incorporation studies revealed that active biosynthesis of metallothionein took place in the kidney as well as in the liver of cadmium-exposed rats. The turnover of ³⁵S-labeled metallothionein was also investigated and the half-lives of the hepatic and the renal metallothionein were found to be 2.8 and 5 days, respectively.     

碱性土壤盐化过程中阴离子对土壤中镉有效态和植物吸收镉的影响

镉是土壤环境中对土壤质量有着极其重要影响的污染物之一,低含量下就能对人体和动物产生危害.镉在土壤中的有效态既决定了它的生物有效性及对环境的危害程度,又是人们对受污染土壤进行治理和修复的基础.作为盐化土壤中的典型组分,无机盐不可避免对镉的有效态及生物有效性等地球化学行为产生明显影响.研究了碱性土壤盐化过程中无机盐阴离子对土壤中镉有效态和植物吸收镉影响.研究方法为:以钠盐为例,实验研究了碱性土壤盐化过程中无机盐阴离子对土壤中镉有效态的影响;通过油菜种植试验,分析了无机盐阴离子对土壤中镉生物有效性的影响.研究结果表明,土壤盐化过程中,土壤溶液中Cl-浓度较低时,土壤中镉的有效态含量随Cl-浓度增加而增大,但当土壤中Cl-/Cd的比值大于100∶1时,土壤中镉的有效态含量达到最大值.土壤溶液中SO42-含量对土壤中镉有效态含量的影响不明显;随着土壤溶液中HCO3-含量的增加,土壤中镉的有效态含量明显减少.由于Cl-、SO42-是土壤溶液中的主要成分,随着盐度的增加,镉的有效态含量增加.油菜种植试验显示,当土壤中Cl-的含量增加时,土壤中镉的有效态含量增加,有利于植物对镉的吸收,因此油菜中镉的含量随土壤中Cl-的含量增加而增加,但当土壤有效态含量超过2 mg/kg后,油菜吸收镉已经达到最大.随着土壤溶液中SO42-浓度的增加,油菜中镉含量基本不变;土壤溶液中HCO3-的含量增加,植物中镉的含量随土壤中HCO3-含量增加而减少.这些特征与土壤镉有效态变化相吻合.通过各种措施控制土壤盐度和调节阴离子类型和含量,有利于降低土壤中镉的有效态含量,减轻镉的活化;农业生产中适当调整无机肥料的种类,可以减少农作物对镉的吸收.     

Mercury,cadmium, zinc and copper concentrations and stable isotope ratios of carbon and nitrogen in tiger sharks (Galeocerdo cuvier) culled off Ishigaki Island,Japan

We analyzed Hg, Cd, Zn and Cu in the liver as well as Hg and stable isotope ratios of carbon and nitrogen (δ¹³C and δ¹⁵N) in muscle from tiger sharks (Galeocerdo cuvier) in Japan. The Hg concentration in the muscle increased slightly and proportionally with increases in body length, but the Hg concentration in the liver increased markedly after maturation (exceeding 2.7 m precaudal length). The Hg concentration in the liver of mature shark was higher than that in the muscle. The Cd concentration in the liver increased with increases in body length. On the other hand, the Zn and Cu concentrations in the liver decreased during the growth stage, but thereafter increased with increased Cd burden due to growth. The marked increase in hepatic Hg in mature sharks may be explained by the continuous intake of Hg via food, slower growth and Hg–Se complex formation. High concentrations of Zn and Cu in the liver of immature sharks and concomitant increases in Zn and Cu with the Cd burden in the liver of mature sharks may be explained by the physiological requirements of Zn and Cu during the growth stage, the induction of metallothionein synthesis due to the Cd burden and the subsequent binding of these metals to metallothionein. The δ¹⁵N and δ¹³C values decreased with increases in body length, suggesting a shift from coastal feeding to pelagic feeding with shark growth. The Hg and Cd concentrations tended to be negatively correlated with the δ¹⁵N and δ¹³C values as a result of the increase in Hg and Cd accumulation due to the growth and the decreases in δ¹⁵N and δ¹³C values due to the sift of feeding area.     

乌鲁木齐市道路林带土壤抗重金属细菌的筛选及重金属去除能力

【背景】道路重金属污染问题日益严峻,寻找高效的微生物资源用于环境修复已迫在眉睫。【目的】从乌鲁木齐市道路林带土壤中筛选抗重金属菌株,并对其重金属去除能力进行探究。【方法】使用含5种重金属离子(铅、镉、锌、铜、镍)的4种培养基进行抗性菌株筛选,通过形态学特征和16S rRNA基因序列进行鉴定,采用电感耦合等离子体发射光谱仪(inductively coupled plasma optical emission spectrometer,ICP-OES)检测分离株对重金属离子的去除情况。【结果】4种分离培养基中,TSA是抗重金属菌株筛选的最适培养基,共筛选出16株抗重金属菌,其中4株抗Pb菌、4株抗Cd菌、4株抗Zn菌、3株抗Cu菌和1株抗Ni菌,其抗性分别高达3 000、800、600、300和400mg/L,16株菌中以芽孢杆菌属(Bacillus)数量最多。在初始浓度为700mg/L Pb²⁺下,菌株Pb6的去除率高达92.48%,菌株Pb11、Pb3和Pb9的去除率分别为27.70%、40.37%和58.88%;在200mg/L Cd²⁺...     

Physiological responses of peanut seedlings to exposure to low or high cadmium concentration and the alleviating effect of exogenous nitric oxide to high cadmium concentration stress

Abstract

The physiological responses of peanut seedlings exposed to low (5 µM) or high (200 µM) cadmium (Cd) concentration and the ability of sodium nitroprusside (SNP, a donor of NO) to reverse the harmful effects of Cd on peanut (Arachis hypogaea L.) were studied. Changes in plant growth parameters, chlorophyll content, antioxidant system, nutrient contents and Cd accumulation were investigated. The results showed that SNP and 5 µM Cd improved plant growth and chlorophyll content. Furthermore, antioxidative system was up-regulated, and as a result, the production rate of superoxide radical (O₂^??) was reduced. Moreover, the absorption of nutrient elements was not impacted, and Cd toxicity was not observed. However, 200 µM Cd had negative effects on the above measured parameters and dramatically increased the accumulation of Cd in all the plant organs. In the 200 µM Cd treatment, addition of 250 µM SNP stimulated plant growth and increased chlorophyll content. It also enhanced the regulation of antioxidative system and reduced the production rate of O₂^?? and malondialdehyde (MDA) content. Besides, SNP supply enhanced the absorption of nutrient elements and restrained the absorption and transport of Cd.     

Reduction of Cadmium Availability to Tobacco (Nicotiana tabacum) Plants using Soil Amendments in Low Cadmium-contaminated Agricultural Soils: A Pot Experiment

Cadmium (Cd) concentration in field-grown tobacco leaves usually ranges from < 0.5 to 5 mg Cd kg^–1 dry matter (DM). Reducing bioavailability of soil Cd by adding amendments to the soil could be suitable to mitigate Cd uptake by tobacco plants. However, little is known on the effect of inorganic amendments on agricultural soils with low Cd concentrations. Therefore, we performed a pot experiment with tobacco plants that were grown during 56 days in two neutral to alkaline agricultural soils with low total Cd concentrations (soil 1 = 0.4, soil 2 = 0.7 mg kg^–1). Both soils were amended or not with 1 or 5% of sepiolite, zeolite, hydroxyapatite and apatite II™. Major and trace elements were measured in mid-stalk position leaves. Soil metals were measured in a DTPA soil extraction to assess the effect of the amendments on metal bioavailability. Some amendments significantly reduced Cd concentration in tobacco leaves, but the effect differed between the two soils tested. In soil 1, the use of zeolite at the 1% dose was the most efficient, reducing the average Cd concentration from 0.6 to 0.4 mg kg^–1. In soil 2, the 5% hydroxyapatite treatment led to the maximal reduction in Cd concentration (50%), with an average final Cd concentration in leaves of 0.7 mg kg^–1 (control: 1.5 mg kg^–1). There was a dose effect for some amendments in soil 2 (containing more Cd), suggesting a reduced efficiency of the amendment at the lowest addition rate. DTPA extractable Cd and Zn measured at the end of the pot experiment were correlated to the metal concentrations in tobacco leaves suggesting that (1) the reduction in leaf Cd concentration was due to a reduction in metal availability to tobacco and (2) DTPA may be a suitable extractant to estimate Cd availability to tobacco plants in these two soils. In addition, a batch experiment was performed with the same soils to test a larger number of amendments, including the four tested in the pot experiment. Results were compared to those of the pot experiment to assess whether a batch experiment may predict the efficiency of an amendment on a given soil. It gave results compatible with those from the pot experiment except for the sepiolite and highlighted the broad range of potential amendments available for heavy metal remediation in crop plants.     

中国沙棘幼苗对土壤镉生理耐性和富集转运特征的性别差异

为探究中国沙棘对土壤镉(Cd)胁迫的性别响应差异,该研究以中国沙棘2年生幼苗为材料,利用盆栽试验研究在不同浓度Cd处理下(0(CK)、25、50、100和200 mg·kg^-1)雌、雄株幼苗的生长、叶片生理特性以及Cd富集特征的差异。结果表明：(1)Cd处理下中国沙棘幼苗雌、雄株的株高和基径生长以及各器官生物量均表现出低浓度(<50 mg·kg^-1)促进,高浓度(> 100 mg·kg^-1)抑制的现象;低浓度Cd处理下雌株的株高、基径增长率和生物量的增幅均高于雄株;高浓度Cd处理下(200 mg·kg^-1)雄株株高增长率、叶生物量和总生物量分别较CK显著降低,而雌株均未显著下降。(2)随着Cd浓度升高,雌、雄株叶片光合色素含量和抗氧化酶活性呈先升后降的变化趋势,丙二醛(MDA)和渗透调节物质含量呈上升趋势;Cd浓度为50～200 mg·kg^-1时,雌株叶片的光合色素含量、抗氧化酶活性和渗透调节物质含量均高于雄株,而MDA含量始终低于雄株。(3)随着Cd浓度升高,雌、...     

Distribution and bioavailability of heavy metals in different particle-size fractions of sediments in Taihu Lake,China

Abstract

Taihu Lake is one of the most important water sources in the economically developed central-eastern part of China, and metal pollution is a major concern for the lake. The distribution and bioavailability of Cd, Cr, Cu, Pb, Sb and Zn were analysed in undifferentiated bottom sediments and in various particle-size fractions of the sediment from different parts of the lake. The average concentration of total metals in undifferentiated sediments ranged from 0.86 mg kg^-1 (Cd) to 95.45 mg kg^-1 (Zn) for the entire lake, with the highest concentrations in Zhushan Bay. The concentration of heavy metals was higher in extremely fine sands (0.064–0.125 mm) and fine sands (0.125–0.25 mm) than in other fractions. Sequential extractions showed that Cu, Zn and Cd were the most bioavailable accounting for 55.6%, 38.7% and 30.0% of their total concentration, respectively. However, the bioavailable proportion of many metals was not significantly different between grain grades except for Cu and Zn, which were higher in silts (<0.064 mm) than in other grades. Compared with the background values of local soils, the concentration of Zn, Cd, Cu, Pb and Sb was higher, indicating enrichment in the sediment. From ecological safety concerns, Zn, Cd and Cu should be examined closely because of their higher bioavailabilty in the sediment.     

THE CONCENTRATION EFFECT WITH VALONIA: POTENTIAL DIFFERENCES WITH DILUTED POTASSIUM-RICH SEA WATERS

The concentration effect with sea waters containing more than the normal amount of potassium has been studied in Valonia macrophysa. This was done by comparing the initial changes in P.D. across the protoplasm when natural sea water bathing the cell was replaced by various isotonic dilutions of KCl-rich sea waters. With small dilutions of KCl-rich sea waters, the P.D.-time curves are of the same form as with the undiluted solution, exhibiting the fluctuations characteristic of KCl-rich solutions. This indicates that with these solutions K⁺ enters Valonia protoplasm and plays an important part in the P.D. The value of the initial rise in P.D. decreases with increasing dilution. With high dilutions of KCl-rich sea waters, the P.D.-time curves are of quite different shape, resembling the curves with diluted natural sea water; the P.D. is practically independent of small changes in the concentration of potassium, and increases with increasing dilution. That is, with these higher dilutions, the sign of the concentration effect is reversed, becoming the same as with diluted natural sea water. The greater the concentration of KCl in the undiluted sea water, the higher is the critical dilution at which K⁺ ceases to influence the P.D. For a wide range of sea waters containing both KCl and NaCl, it is shown that the concentration effect above the critical dilution is determined solely by the activity of NaCl in the external solution. It is concluded that with dilute natural sea water and with high dilutions of KCl-rich sea waters we have to do with a diffusion potential, involving only the Na⁺ and Cl^- ions, which are diffusing out from the vacuole. A quantitative relation between the composition of the sea water and the critical dilution has been deduced from the classical theory of the diffusion of electrolytes. It is shown that with dilutions less than this critical value the diffusion of K⁺ in the outer non-aqueous layer of the protoplasm is directed inward; hence K⁺ enters the protoplasm from these solutions. With dilutions greater than the critical value, the diffusion of K⁺ in this layer is directed outward; hence K⁺ does not enter the protoplasm. Since the P.D. shows no evidence of this outward diffusion of K⁺, it is concluded that the amount of K⁺ ordinarily present in the protoplasm is too small to produce any lasting electrical effect, and that the outward diffusion of K⁺ from the vacuole is prevented by the mechanism responsible for the accumulation of KCl in the cell sap.     

A new method for determining the relation between soil- and plant-cadmium

On soils differing in total Cd concentration, organic matter content and pH, but with the same compost treatment, a significant linear relation was found between the calculated Cd²⁺ concentration of the soil solution and the Cd concentration of lettuce grown under field conditions. The Cd²⁺ concentration was calculated with the equation for the exchange reaction between Cd²⁺ and Ca²⁺.     

Effect of Cl on Cd uptake by Swiss chard in nutrient solutions

Swiss chard (Beta vulgaris L., cv. Fordhook Giant) was grown in nutrient solution with Cl concentrations varying between 0.01 mM and 120 mM. Solution Na concentration and ionic strength were maintained in all treatments by compensating with NaNO₃. All solutions contained Cd (50 nM, spiked with ¹⁰⁹Cd). Three different Cd²⁺ buffering systems were used. In one experiment, Cd²⁺ activity was unbuffered; its activity decreased with increased Cl concentration as a result of the formation of CdCl_n ^2–n species. In the other experiments, Cd²⁺ activity was buffered by the chelator nitrilotriacetate (NTA, 50 M) and ethylene-bis-(oxyethylenenitrilo)-tetraacetate (EGTA, 50 M) at about 10^–9 M and 10^–11 M, respectively. Plant growth was generally unaffected by increasing Cl concentrations in the three experiments. In unbuffered solutions, Cd concentrations in plant tissue decreased significantly (p<0.01) (approximately 2.4-fold) as solution Cl concentration increased from 0.01 mM to 120 mM. However, this decrease was smaller in magnitude than the 4.7-fold decrease in Cd²⁺ activity as calculated by the GEOCHEM-PC program for the same range of Cl concentrations. In solutions where Cd²⁺ activity was buffered by NTA, Cd concentrations in plant tissue increased approximately 1.4-fold with increasing Cl concentration in solution, while the Cd²⁺ activity was calculated to decrease 1.3-fold. In solutions where Cd²⁺ activity was buffered by EGTA, Cd concentrations in the roots increased 1.3-fold with increasing Cl concentration in solution but there was no effect of Cl on shoot Cd concentrations. The data suggest that either CdCl_n ^2–nspecies can be taken up by plant roots or that Cl enhances uptake of Cd²⁺ through enhanced diffusion of the uncomplexed metal to uptake sites.Abbreviations DAS days after sowing - EGTA ethylene-bis-(oxyethylenenitrilo)-tetraacetate - HBED N,N-bis(2-hydroxybenzyl)-ethylenediamine-N,N-diacetate - NTA nitrilotriacetate     

土壤不同镉水平对马缨丹生长及其抗氧化酶活性的影响

采用盆栽试验方法,分别设置0(对照,不添加镉)、30、60、90、120、150、180、210mg·kg-1共8个土壤镉处理水平,研究土壤不同镉水平对马缨丹(Lantana comara L.)生长及其抗氧化酶活性的影响,以探讨马缨丹对镉胁迫的生理响应机制。结果显示:(1)随着土壤镉处理浓度的升高,马缨丹干重呈先升高后降低的趋势,30mg·kg-1镉处理能促进植株的生长,而浓度高于60mg·kg-1时显著抑制马缨丹的生长。(2)马缨丹叶片和根系中O-·2产生速率、H2O2和MDA含量及电解质渗漏率均随土壤镉处理浓度的升高和胁迫时间的延长逐渐升高,胁迫90d时,叶片和根系中O-·2产生速率、H2O2和MDA含量及电解质渗漏率分别在镉浓度高于60和30mg·kg-1时显著低于对照。(3)叶片和根系抗氧化酶SOD、POD、APX和CAT活性随着土壤镉处理浓度的增加大体呈先升高后降低的趋势,并在镉浓度分别高于90和60mg·kg-1时,叶片和根系抗氧化酶活性显著低于对照。研究表明,低浓度镉处理土壤能促进马缨丹植株生长,而高浓度镉处理土壤显著降低了马缨丹体内抗氧化酶活性,导致活性氧大量积累,引起严重的膜脂过氧化伤害,从而显著抑制马缨丹植株的生长。     

消胀散敷脐联合腹水超滤浓缩回输治疗肝硬化顽固性腹水的疗效及对肝肾功能、电解质和生活质量的影响

摘要 目的：观察消胀散敷脐联合腹水超滤浓缩回输治疗肝硬化顽固性腹水的疗效及对肝肾功能、电解质和生活质量的影响。方法：选取2017年1月-2020年12月在我院肝病科住院治疗的肝硬化顽固性腹水患者64例,根据随机数字法分为对照组（腹水超滤浓缩回输治疗,32例）和治疗组（消胀散敷脐联合腹水超滤浓缩回输治疗,32例）。观察两组治疗前和治疗4周后的疗效、腹水消退率、体质量、腹围、24 h尿量变化、肝肾功能指标、血电解质指标和生活质量测定量表简表（QOL-BREF）评分,并记录两组治疗期间不良反应（包括皮肤红疹、瘙痒等）发生情况。结果：治疗组治疗4周后的临床总有效率高于对照组（P<0.05）。治疗组治疗4周后腹水消退率显著优于对照组（P<0.05）。治疗组治疗4周后体质量、腹围小于对照组,24 h尿量多于对照组（P<0.05）。治疗组治疗4周后丙氨酸氨基转移酶（ALT）、谷草转氨酶（AST）、尿素氮（BUN）、胱抑素C(CysC)低于对照组（P<0.05）。两组治疗前、治疗4周后组间及组内对比钾（K⁺）、钠(Na⁺)、氯（Cl^-）均无统计学差异（P>0.05）。治疗组治疗4周后社会关系领域、生理领域、环境领域、心理领域评分均高于对照组（P<0.05）。治疗期间两组不良反应发生率对比无统计学差异（P>0.05）。结论：消胀散敷脐联合腹水超滤浓缩回输治疗肝硬化顽固性腹水,可提高临床治疗效果,改善患者的肝肾功能和生活质量,同时对机体电解质影响不大,安全可靠。     

Involvement of IAA in the interaction betweenAzospirillum brasilense andPanicum miliaceum roots

The possible involvement of IAA in the effect thatAzospirillum brasilense has on the elongation and morphology ofPanicum miliaceum roots was examined by comparing in a Petri dish system the effects of inoculation with a wild strain (Cd) with those of an IAA-overproducing mutant (FT-326). Both bacterial strains produced IAA in culture in the absence of tryptophan. At the stationary growth phase, production of IAA by FT-326 wasca. 12 times greater than that of Cd. When inoculation was made with bacterial concentrations higher than, 10⁶ colony forming units ml^–1 (CFU ml^–1), both strains inhibited root elongation to the same extent. At lower concentrations Cd enhanced elongation, by 15–20%, while FT-326 was ineffective. Both strains promoted root-hair development, and root-hairs were produced nearer the root tip the higher the bacterial concentration (e. g. root elongation region was reduced). Effects of FT-326 on root-hair development were greater than those of Cd. Acidified ether extracts of Cd and FT-326 cultures had inhibitory or promoting effects on root elongation depending on the dilution applied. At low dilutions, extracts from FT-326 were more inhibitory for elongation than those from Cd. At higher dilutions root elongation was promoted, but FT-326 extracts had to be more diluted than those from Cd. Dilutions that promoted root elongation contained supra-optimal concentrations of IAA, 1–3 orders of magnitude higher than those required for optimal enhancement by synthetic IAA. It is suggested that the bacteria produce in culture an IAA-antagonist or growth inhibitor that decreases the effectiveness of IAA action. The large variability reported for the effects ofAzospirillum on root elongation could be the result of the opposite effects on root elongation of IAA and other compounds, produced by the bacteria.