Diquat enhancement of cupric ion toxicity

Cupric ion inhibition of Chlorella growth and photosynthesis and electron transport in isolated chloroplasts was enhanced by concentrations of diquat (6,7-dihydrodipyrido[1,2-a:2′,1′-c]pyrazinediium) that did not inhibit these processes in the absence of cupric ions. Diquat decreased the lag in cupric ion inhibition of Chlorella photosynthesis from 5 to 3.3 min. Diquat enhancement of cupric ion toxicity was immediate with no lag when diquat was added to Chlorella cells with photosynthesis inhibited by cupric ions. Diquat was absorbed by isolated chloroplasts with an intact outer envelope and the absorption was not due to diquat binding to chloroplast membranes. Cupric ion movement through the outer envelope of chloroplasts was stimulated by the presence of diquat. Cupric ion toxicity was also increased by diquat in bicarbonate solutions. The optimum molar ratios of cupric ions to diquat among those tested for diquat enhancement of cupric ion toxicity were 1:0.188 and 1:0.2, which are 1:1 and 1:1.08 on a parts per million basis.     

Prevention of Phytophthora Root Rot in Gerbera by increasing copper ion concentration in the nutrient solution

Increased copper concentration in the nutrient solution was used as a means for reducing the severity of root rot caused by Phytophthora cryptogea in Gerbera jamesonii in three experiments. Plants were grown in pots on ebb-and-flow benches with separate systems for recirculating nutrient solutions. Eight nutrient solutions with two concentrations of copper ions (0.07 and 0.28 ppm), two electrical conductivity values (1.5 and 2.2 mScm^-1), and two iron sources (FeHEEDTA or FeSO₄) were combined in a factorial design. Plants were inoculated with zoospores of P. cryptogea via the recirculating nutrient solution. Disease incidence was significantly reduced in inoculated plants grown on nutrient solution with 0.28 ppm copper compared with 0.07 ppm copper, when FeSO₄was introduced as the iron source. No effects of increased copper concentration was observed when iron was added as FeHEEDTA. The change in electrical conductivity from 1.5 to 2.2 mScm^-1 without changing the Cu²⁺ concentration did not influence the disease severity in these experiments. The results suggest that increased copper ion concentration in the nutrient solution could be a component of disease management strategy for ebb-and-flow systems. Possible management of the cupric ion concentration in the nutrient solutions is discussed.     

Correlation of physico‐chemical parameters with toxicity of metal ions to plants

The in vivo toxicities of 12 metal ions to cabbage plants have been correlated with ion‐specific physico‐chemical parameters. Several regression models were statistically significant but two different electronegativities in combination with Kaiser's electrochemical potential appeared to be the best determinants of metal ion toxicity, giving a good correlation (r²adjusted = 0.81 for 11 metal ions excluding copper, and 0.66 for all 12 metal ions). © 2000 Society of Chemical Industry     

Purification and properties of pyrethroid carboxyesterase in rat liver microsome

Pyrethroid carboxyesterase which hydrolyzes the esters of chrysanthemumic acid was purified from rat liver microsome by cholic acid solubilization, ammonium sulfate fractionation, heat treatment, and DEAE-Sephadex A-50 column chromatography. The 45-fold purified enzyme (38% yield) is likely to consist of single protein, as evidenced by polyacrylamide gel disc electrophoresis and Sephadex G-100 column chromatography, and had a molecular weight of approximately 74,000 and a K_m of 0.21 mM. It is susceptible to inhibition by organophosphates and carbamate insecticides and insensitive to pCMB, mercuric ion, and cupric ion. It is capable of hydrolyzing trans isomers of synthetic pyrethroids much more rapidly (five to ten times) than the cis counterparts. The purified pyrethroid carboxyesterase is apparently identical in nature with malathion carboxyesterase and with p-nitrophenyl acetate carboxyesterase.     

Effect of GRAS compounds on Aspergillus rot of wood-apple (Feronia limonia)

Fruit rot caused by Aspergillus niger is a major postharvest problem in wood-apple, Feronia limonia Swingle (syns. F. elephantum Correa; Limonia acidissima L.; Schinus limonia L. [Rutaceae]). The effect of four Generally Recommended As Safe (GRAS) compounds—sodium bicarbonate, calcium chloride, citric acid and sodium benzoate—in different concentrations was evaluated on mycelium growth and spore germination. The effectiveness of the compounds was investigated on inoculated and naturally infected fruits. Sodium bicarbonate (4%) completely inhibited the mycelial growth and spore germination. Fruits that were first inoculated and then treated with 4% sodium bicarbonate, or the reverse, gave 53.6% and 98.4% disease reduction, respectively. Non-treated control fruits were diseased completely 3 days after inoculation. Sodium bicarbonate treatment on naturally infected fruits controlled the disease by 100% and extended the storage life up to 28 days at 27?±?2°C and 65–70% r.h. Sensory attributes of the treated fruits did not change during storage.     

Influence of metal salts on the photodegradation of imazapyr, an imidazolinone pesticide

The behaviour of imazapyr (2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid), a broad spectrum herbicide of the imidazolinone family, has been studied under UV radiation in the presence of metal salts. Complexation interactions between imazapyr and metal ions decreased imazapyr photolysis. A chemometric study compared the photodegradation of imazapyr in aqueous solutions in the presence of Na+, Ca2+ or Cu2+ and their concomitant anionic species (Cl-, NO3-) at various pesticide/metal ion molar ratios. The study showed the major role of metal ions in the degradation of imazapyr and its main photoproducts. The molecules were strongly stabilised on complexation with metal ions, leading to an increase in persistence of the pesticide.     

植物提取物、碳酸钠和碳酸氢钠室内对杨树溃疡病菌生长的抑制作用

 采用菌丝生长速率法用金银花的花、黄花蒿的地上部分、蓝桉果实和黄柏果实的乙醇提取物及其不同极性的组分对杨树溃疡病菌菌丝生长的抑制作用进行了测定。以黄柏果实的抗菌活性最强,其次是金银花的花。抗菌活性成分主要存在于金银花的正丁醇组分、黄花蒿的石油醚组分和乙酸乙酯组分、蓝桉的水部分、黄柏的正丁醇组分。当培养基中碳酸钠和碳酸氢钠的浓度分别为8g/L时(对应的pH值分别为10.24和7.71),菌丝生长抑制率分别为100.00%和79.68%。如果用1mol/L氢氧化钠溶液调节培养基的pH值至10.00,菌丝生长抑制率为40.58%。说明碳酸钠或碳酸氢钠对菌丝生长的抑制作用,一方面是由于改变了培养基的pH值,另一方面可能是由于碳酸根和碳酸氢根离子抑制了菌丝的生长。     

Similarity between Copper Resistance Genes from Pseudomonas syringae pv. actinidiae and P. syringae pv. tomato

Twenty-eight strains of Pseudomonas syringae pv. actinidiae isolated in 1984, 1987 and 1988 from kiwifruit orchards in Japan were tested for their resistance to copper sulfate. All strains isolated in 1984 were copper sensitive with a minimum inhibitory concentration (MIC) of cupric sulfate of 0.75 mM. However, some strains isolated in 1987 and 1988 were resistant, with the MIC ranging from 2.25 to 3.0 mM. All copper-resistant strains contained at least one of two plasmids, pPaCul (about 70.5 kb) or pPaCu2 (about 280 kb), or both. In a copper-resistant strain Pa429, the location of the copper-resistance gene(s) was examined by insertional inactivation with Tn5. The MIC of copper sulfate in the copper-sensitive mutant obtained by Tn5 tagging decreased from 2.75 to 0.75 mM. The 14.5 kb BamHI fragment, designated pPaCuB14, containing the same locus mutagenized with Tn5 was cloned from pPaCu1. However, pPaCuB14 did not confer copper resistance in the transformant of copper-sensitive strain Pa21R, suggesting that this clone did not contain a full set of copper-resistance gene(s). Then a cosmid library of pPaCu1 was constructed and six cosmid clones hybridized with pPaCuB14 were selected. One of the six cosmids, designated pPaCuC1, conferred a near wild-type level of copper resistance in the transformant of the copper-sensitive strain. pPaCuC1 had a homologous region that hybridized with all of the PCR-amplifled fragments of copA, copB, copR, and copS genes of P. syringae pv. tomato. DNA sequence analysis of the homologous region revealed the existence of four open reading frames (ORF A, B, R and S) oriented in the same direction. The predicted amino acid sequences of ORF A, B, R and S had 80, 70, 97 and 95% identity with CopA, B, R and S of P. syringae pv. tomato, respectively. Received 5 July 2001/ Accepted in revised form 27 September 2001     

Copper Resistance in Pseudomonas syringae Strains Isolated from Mango Is Encoded Mainly by Plasmids

ABSTRACT Bacterial apical necrosis of mango, elicited by Pseudomonas syringae pv. syringae, limits fruit production in southern Spain and Portugal. Examination of a collection of P. syringae pv. syringae isolates for copper resistance showed that 59% were resistant to cupric sulfate. The survey of a mango orchard revealed an increase in frequencies of copper-resistant bacteria after repeated treatments with Bordeaux mixture. These data suggest that selection of copper-resistant strains could be a major reason for control failures following management with copper bactericides. Most copper-resistant isolates harbored plasmids, although the majority of them contained a 62-kb plasmid that also was present in copper-sensitive strains. The 62-kb plasmids were differentiated by restriction enzyme analysis and hybridization to copABCD DNA. The most frequently found copper-resistant plasmid type (62.1) was transferable by conjugation. Southern blot hybridizations showed that genetic determinants partially homologous to copABCD were present in all the copper-resistant strains examined, and usually were associated with plasmids; these determinants were not detected in copper-sensitive strains. The selective pressure exerted by copper bactericide sprays on the diversity of copper resistance determinants in bacterial populations of mango is discussed.     

草酸二丙酮胺-铜配合物的合成、结构表征及抑菌活性

报道了新化合物——草酸二丙酮胺-铜配合物的合成、结构表征及抑菌活性。目标化合物由二丙酮胺草酸盐与氯化铜在去离子水中反应制得,在乙醇溶液中获得单晶,经元素分析、红外光谱以及X-射线单晶衍射技术确定了其结构。采用抑制孢子萌发法测定了其对6种农业病原真菌的离体抑制活性。结果表明:当配合物中草酸、铜与二丙酮胺的物质的量之比为2∶ 1∶ 2时,其对6种供试病原真菌均表现出强烈的抑菌活性,毒力与对照药剂80%的代森锌可湿性粉剂相当。     

The interaction of folpet with the glutathione-dependent demethylation enzyme system of rat liver

The interaction of folpet with the glutathione-dependent enzyme demethylation of fenitrothion was studied. In a reaction catalyzed by methyltransferase from rat liver in the presence of 0.3 μmol of glutathione, 0.21 μmol of folpet caused a 100% inhibition of the demethylation of 0.2 μmol of fenitrothion. A parallel study was made on the qualitative and quantitative course of the reaction between folpet and glutathione. Phthalimide was formed as the main degradation product of folpet, but the composition of the degradation products of glutathione was dependent on the molar ratio of the reactants. Compounds absorbing at 267 nm (probably derivatives of 2-thiazolidinethiones) were formed when the ratio of glutathione to folpet was 4.5:1. When this ratio was reversed, oxidized glutathione was the main product. From observations on the course of the enzymatic demethylation of fenitrothion and on the degradation of folpet by glutathione, it appears that in the enzyme demethylation system, the reaction between fungicide and glutathione predominates.     

Fate of copper in ponds.

Treatments of 3 ppm copper sulfate (CuSO4-5H2O) were applied to two small aquatic systems in Michigan in 1971. To study the pathways of the added copper, samples of water, sediment, aquatic macrophytes, filamentous algae, and fish were collected and analyzed by atomic absorption. Sampling was initiated before treatment and continued up to 4 months in one of the ponds. Dissolved copper concentrations in water decreased rapidly immediately after treatment and then gradually to background levels. Reduction of dissolved copper may have involved initial precipitation of an insoluble compound, such as malachite, followed by sediment adsorption of soluble copper complexes and copper released from aquatic plants. Levels of copper in sediment increased rapidly at first and gradually later in the study. Aquatic plants and filamentous algae accumulated very high levels of copper. Uptake rates were apparently affected by water temperature and growth stages of the plants. Data indicate that aquatic macrophytes developing in one pond 10 weeks after treatment took up copper from the sediment. Although green sunfish (Lepomis cyanellus) accumulated copper soon after treatment, levels returned to background later in the study.     

黄瓜品种资源芽苗期和幼苗期耐盐性及其评价指标研究

采用NaCl水溶液人工模拟盐胁迫,以多项指标的盐害系数为依据,比较了18个黄瓜品种资源在芽苗期和幼苗期的耐盐性及其两个时期耐盐性的相关性,并对两个时期各品种资源的耐盐性通过聚类分析进行了分类。结果表明:芽苗期的总盐害系数与发芽势、发芽率、发芽指数、下胚轴长、根长、地上部鲜重、根鲜重、活力指数的盐害系数的相关性达极显著水平;幼苗期与总盐害系数相关性达极显著水平的有地上部鲜重、地下部鲜重、地下部干重、壮苗指数、根/冠,达显著相关水平的有地上部干重,叶绿素a/b和叶绿素(a b)/类胡萝卜素的盐害系数与总盐害系数相关性不显著。从两个时期的聚类分析图来看,它们的耐盐性并不相同。黄瓜品种资源耐盐性的强弱在芽苗期和幼苗期表现明显不同。在进行黄瓜芽苗期耐盐性筛选时可以将发芽势、发芽率、发芽指数、活力指数、下胚轴长、地上鲜重、根鲜重综合起来作为评价指标。在对黄瓜幼苗期耐盐性鉴定时可以用地上部和地下部鲜重、地上部和地下部干重、壮苗指标、根/冠来衡量黄瓜材料在幼苗期耐盐性的强弱。     

Influence of Dissolved Organic Carbon and Initial Moisture on Zinc Sorption by Two Arid Soils

Sorption of added zinc to irrigated soils in arid regions is an important process that may control the availability of zinc to growing plants . Two soil surface samples varying in clay , organic matter , and calcium carbonate content were selected from central and southwestern regions of Saudi Arabia and prepared in order to give different initial moisture contents ranging from air dried to 100 % of field capacity . The sorption experiment was conducted using Zn concentrations ranging from 5 to 25 mg L 1, prepared from ZnSO4 either in distilled water or in solutions containing 75 mg L 1 dissolved organic carbon (DOC). Results indicate that the amount of Zn sorbed in the presence of DOC was relatively high compared with the absence of DOC and Zn retention was strongly affected by the initial soil moisture content . Also , equilibrium Zn concentrations were quite low , while Zn retentions were high in all treatments . Data of Zn sorption were described by the Freundlich isotherm , and two linear portions were found in most cases . In the absence of DOC , retentions of added Zn were controlled by the available exchange sites and / or the precipitation of Zn as sparingly soluble forms. Zn ions in the presence of DOC were able to form soluble - Zn organic complexes that adsorb on the soil surfaces . The extent of such behavior was related to the variations in clay , organic matter , and calcium carbonate contents as well as the initial moisture of the soil . Results indicate that addition of DOC reduces the amount of extractable Zn from either soil Zn or the sorbed Zn by ammonium bicarbonate diethylenetriamine pentaacetic acid ( AB DTPA ). More than 80 % of the sorbed Zn was extracted by AB-DTPA , and the percentage of extracted / sorbed Zn decreased with the increase in sorbed Zn . The obtained results give evidence that initial moisture content and addition of DOC reduce the extractability of applied inorganic Zn by AB-DTPA extract in arid soils.     

生长刺激剂及微量元素对于棉苗保健作用的效应

 过去,国內外許多学者証明,适当的应用微量元素和生长刺激剂处理种籽,对农作物苗期生长有促进作用,也常常收到提高产量的效果。关于应用于棉籽处理方面,波波甫应用了溴化鉀浸种,显著的提高了棉花的产量。     

Efficacy of phosphonic acid, metalaxyl-M and copper hydroxide against Phytophthora ramorum in vitro and in planta

The ability of metalaxyl-M, phosphonic acid in the form of phosphonate, and copper hydroxide to inhibit different stages in the life cycle of Phytophthora ramorum , the causal agent of sudden oak death (SOD), was tested in vitro using 12 isolates from the North American forest lineage. In addition, experiments were conducted in planta to study the ability of phosphonic acid injections and metalaxyl-M drenches to control pathogen growth on saplings of California coast live oak ( Quercus agrifolia ), and of copper hydroxide foliar sprays to control infection of California bay laurel ( Umbellularia californica ) leaves. Phytophthora ramorum was only moderately sensitive to phosphonic acid in vitro , but was highly sensitive to copper hydroxide. In planta experiments indicated the broad efficacy of phosphonic acid injections and of copper hydroxide sprays in preventing growth of P. ramorum in oaks and bay laurels, respectively. Finally, although metalaxyl-M was effective in vitro , drenches of potted oak trees using this active ingredient were largely ineffective in reducing the growth rate of the pathogen in planta .     

硫磺改良盐渍土效果初探

采用田间试验方法,探索了以硫磺为改土材料对渭南盐渍土的初步改良效果。结果表明,硫磺的施用对于土壤及作物(棉花)的养分状况表现出一定的改善作用;并且降低了土壤pH值,相对于施用石膏的处理,硫磺在降低土壤pH上有更明显的作用;另外,虽然硫磺的施用增加了土壤中各离子的含量及EC值,但随着硫磺用量的逐渐增加,土壤中各离子含量及EC值呈现出降低的趋势。因此,硫磺的施用对于该地土壤具有一定的改良作用。但是,虽然结果显示硫磺在该地土壤的改良中起到了一定的作用,但总体效果有限,其主要原因可能是硫磺施用量太低(试验中最高用量为225 kg/hm2),因此,在本试验基础上如果进一步加大硫磺用量将可能会对该地盐碱化土壤具有更为明显的改良作用,但最佳施用量还需要进一步研究。     

低分子量有机酸对粘土矿物吸附二氯喹啉酸的影响

采用批量平衡法,研究了6种低分子量有机酸(柠檬酸、酒石酸、苹果酸、乙酸、草酸和丁二酸)对3种粘土矿物(高岭土、蒙脱石、凹凸棒石)吸附二氯喹啉酸的影响。结果表明:当低分子量有机酸存在时,供试3种粘土矿物对二氯喹啉酸的吸附过程可用Linear和Freundlich吸附等温方程描述,且Freundlich方程的拟合效果更好。供试6种有机酸对二氯喹啉酸在高岭土中吸附量的影响程度从低到高依次为苹果酸<柠檬酸<草酸<乙酸<酒石酸<丁二酸,在蒙脱石中的顺序为乙酸<草酸<苹果酸<丁二酸<酒石酸<柠檬酸,在凹凸棒石中的顺序为乙酸<丁二酸<草酸<苹果酸<酒石酸<柠檬酸。不同浓度低分子量有机酸对3种供试粘土矿物吸附二氯喹啉酸均能产生显著的影响,但影响程度因粘土矿物和有机酸种类的不同而有较大差异。     

Use of Fatty Acid Methyl Ester Profiles to Compare Copper-Tolerant and Copper-Sensitive Strains of Pantoea ananatis

ABSTRACT A survey was conducted to evaluate differences in fatty acid methyl ester (FAME) profiles among strains of Pantoea ananatis, causal agent of center rot of onion (Allium cepa), isolated from 15 different onion cultivars in three different sites in Georgia. Differences in FAME composition were determined by plotting principal components (PCs) in two-dimensional plots. Euclidean distance squared (ED(2)) values indicated a high degree of similarity among strains. Plotting of PCs calculated from P. ananatis strains capable of growing on media amended with copper sulfate pentahydrate (200 mug/ml) indicated that copper-tolerant strains grouped into tight clusters separate from clusters formed by wild-type strains. However, unlike copper-sensitive strains, the copper-tolerant strains tended to cluster by location. A total of 80, 60, and 73% of the strains from Tift1, Tift2, and Tattnall, respectively, exhibited either confluent growth or partial growth on copper-amended medium. However, all strains were sensitive to a mixture of copper sulfate pentahydrate (200 mug/ml) and maneb (40 mug/ml). When copper-tolerant clones were analyzed and compared with their wild-type parents, in all cases the plotting of PCs developed from copper-tolerant clones formed tight clusters separate from clusters formed by the parents. Eigenvalues generated from these tests indicated that two components provided a good summary of the data, accounting for 98, 98, and 96% of the standardized variance for strains Pna 1-15B, Pna 1-12B, and Pna 2-5A, respectively. Furthermore, feature 4 (cis-9-hexadecenoic acid/2-hydroxy-13-methyltetradecanoic acid) and feature 7 (cis-9/trans-12/cis-7-octadecenoic acid) were the highest or second highest absolute values for PC1 in all three strains of the parents versus copper-tolerant clones, and hexadecanoic acid was the highest absolute value for PC2 in all three strains. Along with those fatty acids, dodecanoic acid and feature 3 (3-hydroxytetradecanoic acid/14-methylpentadecenoic acid) also had an impact on the differences observed between copper-sensitive parents and copper-resistant mutants. Finding these changes in bacterial fatty acid composition could lead to the development of a laboratory assay to identify copper-tolerant strains using gas chromatography as well as providing clues to further elucidate the mode of action of copper tolerance.     

氮肥对保水剂吸水保肥性能的影响

测定保水剂在不同氮肥(尿素、碳酸氢铵、硝酸铵、硫酸铵、氯化铵)溶液中的吸水倍率和对肥料养分的吸持量,分析不同氮肥对保水剂吸水、保肥性能的影响。结果表明:保水剂在各种氮肥溶液中吸水倍率显著下降,并随肥料浓度的增加下降幅度增加;受影响程度聚丙烯酸钠盐型保水剂大于聚丙烯酰胺-丙烯酸盐型保水剂;不同氮肥对保水剂吸水倍率的影响按尿素、碳酸氢铵、硝酸铵、硫酸铵、氯化铵顺序递增。保水剂在大量吸水的同时,也对溶液中的肥料分子或者离子有吸持作用,吸持量均随肥料浓度的增加而增加;保水剂和肥料品种不同,吸持量也不同;除尿素外,保水剂对肥料的吸持率随肥料浓度的增加而降低,最高浓度下,吸持率按硝酸铵、碳酸氢铵、氯化铵、硫酸铵、尿素次序依次增大。