TOXIC EFFECTS OF HEAVY METALS ON CROP PLANTS GROWN IN SOIL CULTURE

A number of pot experiments were made on various crops, to study the effects on the chemical composition of the plants of treating the soil with cobalt, copper or nickel sulphates, or with the cupric or ferric salts of ethylenediamine-tetraacetic acid (EDTA).
The tops of copper sulphate-treated plants usually contained higher concentrations of copper, manganese, calcium and magnesium and lower concentrations of potassium and phosphorus, than those of control plants.
The most marked effect of cobalt on oat was to increase the concentration of Ca+Mg in the tops; nickel had a profound effect on the composition of barley tops.
Total iron concentration was reduced in oat by cobalt and copper, and in barley by copper and nickel application. Symptoms of iron deficiency appeared only in the oat plants, their incidence being correlated with the reduction in iron concentration in the tops.
The ferric salt of EDTA tended to reduce the incidence of iron deficiency symptoms produced in oat by copper sulphate, but also gave rise to distinct toxic effects. Plants given the cupric salt of EDTA contained unusually large amounts of iron.     

Comparisons of nine heavy metals in salt gland and liver of greater scaup (Aythya marila), black duck (Anas rubripes) and mallard (A. platyrhynchos)

Levels of nine heavy metals were measured in the livers and salt glands of greater scaup (Aythya marila), black duck (Anas rubripes) and mallard (A. platyrhynchos) from Raritan Bay, New Jersey to determine if the functioning avian salt gland concentrates heavy metals. Heavy metals examined were cadmium, cobalt, chromium, copper, lead, mercury, manganese, nickel and zinc. Heavy metal levels varied significantly by species and tissue for chromium, copper, lead, and manganese, and by tissue for cobalt, mercury, nickel and zinc. In comparing tissues cobalt was higher in the salt glands than in livers of all three species; chromium and nickel were higher in the salt gland than liver for mallard and black duck; and lead, manganese and zinc were higher in the liver than the salt gland in greater scaup. Generally metal levels were higher in the salt gland for mallard and black duck, and in the liver for greater scaup.     

TRACE-ELEMENT TOXICITIES IN OAT PLANTS

Excessive amounts of nickel, cobalt, chromium, copper, zinc, manganese, molybdenum and aluminium in nutrient solutions supplied to oat plants in sand culture produce ( a ) chlorosis and ( b ) other symptoms specific to the element involved. The specific symptoms are distinct for each metal, although those of cobalt and nickel might be confused.
The toxic effects of nickel, cobalt, copper, zinc, manganese and molybdenum are associated with high concentrations of the element in the leaf tissue, but this is not always so with chromium and aluminium.
The toxic effects of nickel, chromium, copper and molybdenum are associated with a reduced nitrogen content of the plant. Nickel, cobalt, chromium, zinc and manganese increase the concentration of phosphorus in the tissue whilst aluminium decreases it, probably to a deficiency level.
Aluminium reduces the intensity of toxic symptoms produced by nickel—probably by reducing the uptake of nickel and phosphorus. Copper effectively reduces the leaf necrosis produced by nickel, but not the nickel content of the leaf tissue; it is suggested that one factor in nickel toxicity may be inhibition of one or more functions of copper. The other elements slightly increase chlorosis and some increase necrosis.
The order of activitjl of the elements in producing chlorosis is found to be Ni>Cu>Co>Cr>Zn>Mo>Mn. This order, which is related to that giving yield reduction and is similar to the order of stability of metal complexes, is discussed in relation to induced iron deficiency.     

Seminal plasma trace metal levels in industrial workers

This study compares the seminal plasma trace metal levels of hospital workers with groups of industrial workers in a petroleum refinery, smelter, and chemical plant. The metals measured were the essential metals (copper, zinc, nickel, cobalt, and manganese) and the toxic metals (lead, cadmium, and aluminum). The group mean±SE metal level for each group (50 subjects per group) was calculated, and the statistical significance of the group mean differences of the industrial groups with the hospital group (control) was determined by the Student’s t-test. The differences observed in the smelter group were increased copper and zinc (p≤0.001) and decreased nickel, cobalt, and manganese (p≤0.001,≤0.01). The refinery group differences were increased copper, zinc, and nickel (p≤0.001) but decreased cobalt and manganese (p≤0.001). The chemical group differences were increased zinc (p≤0.001) and decreased cobalt (p≤0.001). The seminal plasma levels of the toxic metals lead and aluminum were increased in each of the industrial groups (p≤0.001). Concurrent differences were (1) decreased accumulation of nickel, cobalt, and manganese in the smelter group, (2) decreased cobalt and managanese in the refinery group, and (3) only decreased cobalt in the chemical group.     

Metalloporphyrin mediated DNA cleavage by a low concentration of HaeIII restriction enzyme

The plasmid DNA scission by the restriction enzyme HaeIII was investigated in the presence of tetrakis(1-methylpyridinium-4-yl)porphyrin (H2TMPyP) and its manganese(III), iron(III), nickel(II), cobalt(III) and zinc(II) derivatives. The effect of metalloporphyrins on plasmid DNA cleavage was ascertained by gel electrophoresis. UV-Vis absorption spectroscopy and circular dichroism (CD) spectroscopy. In the absence of the metalloporphyrins, plasmid DNA scission did not occur in the presence of a low concentration of HaeIII (0.2 units microL(-1)) at 37 degrees C after 1 h incubation. However, DNA cleavage occurred in the presence of the metalloporphyrins and HaeIII (0.2 units microL(-1)) at 37 degrees C after 1 h incubation. Gel electrophoresis results indicate the catalytic effect of metalloporphyrins (Mn(III)-, Fe(III)-, Co(III)- and Zn(II)TMPyP) by binding to both DNA and the enzyme through electrostatic interaction, which was confirmed by the change in UV-Vis and CD spectra. A mechanism for the enhanced DNA cleavage is proposed.     

Metal complexes of the schiff bases 2-pyridinylhydrazine and 2-quinolinyl-hydrazine with 2-pyridinecarboxaldehyde N-oxide,including some N-oxide-bridged antiferromagnetic complexes of cobalt(II) and nickel(II)

Metal complexes of 2-pyridine carboxaldehyde 2′-pyridinylhydrazone 1-oxide (poph) and 2-pyridinecarboxaldehyde 2′-quinolinylhydrazone 1-oxide (poqh) are reported with copper(II), nickel(II), cobalt(II), iron(II) and manganese(II). Each ligand appears to function as an ONN donor, via the pyridine N-oxide oxygen, the imine nitrogen, and a pyridine or quinoline nitrogen. The complexes have been characterised by magnetic susceptibility measurements to liquid nitrogen temperature, and also by electronic, infrared, X-ray powder diffraction, and Mössbauer spectra. No magnetic interaction was detected with the copper(II) complexes. All the complexes of metal nitrates appear to be monomers.The complexes of poph with the halides and thiocyanates of nickel(II) and cobalt(II) appear to be six-coordinate and N-oxide-bridged; they exhibit varying degress of antiferromagnetic interaction and the magnetic data for the nickel(II) complexes have been fitted to various models. In contrast, the bulky ligand poqh produces halide-bridged six-coordinate nickel(II) complexes and monomeric five-coordinate cobalt(II) complexes.This behaviour by poqh resembles that of the related NNN ligands paphy and paqhy, which are the Schiff bases of 2-pyridinecarboxaldehyde with 2-pyridinylhydrazine and 2-quinolinylhydrazine, respectively.     

Complexes of dibenzoyldisulphide with metal halides. Part III. Complexes of dibenzoyldisulphide with cobalt(II), nickel(II), manganese(II), copper(II), iron(III) and chromium(III) halides

Adducts (1:1) of halides of cobalt(II), nickel(II), manganese(II), copper(II), iron(III) and chromium(III) with dibenzoyldisulphide have been isolated and characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility, infrared spectra, molecular weight and thermogravimetric analysis data.     

Heavy metals in some Chinese herbal plants

The concentrations of nine heavy metals, cadmium, cobalt, copper, iron, manganese, nickel, lead, zinc and mercury in 42 Chinese herbal medicinal plants were determined. Generally, all the samples studied had, relative to the other trace metals, higher concentrations of iron, manganese, and zinc. The concentration range of the metals determined was comparable to that in many of the East Asian vegetables and fruits. A few samples were found to contain relatively higher concentrations of the toxic metals such as cadmium, lead, and mercury. This was probably caused by contamination during air-drying and preservation.     

Decrease in oxygen affinity of myoglobin by formylation of vinyl groups of heme.

Three kinds of green synthetic myoglobin were prepared by recombination of horse heart apomyoglobin with spirographis (2-formyl-4-vinyl-), isospirographis (2-vinyl-4-formyl-), and 2,4-diformyldeuterohemins. The optical and oxygen binding properties of the reconstituted myoglobins containing two isomeric monoformyl-monovinylhemins were found to be different. The oxygen affinities (P50) of spirographis and 2,4-diformylmyoglobins are 2.7 and 2.8 mm Hg, respectively, at 25 degrees, and about 2.5 times lower than that of native protomyglobin, while that of isospirographis myoglobin is 1.0 mm Hg and is similar to native myoglobin. Spirographis oxymyoglobin has absorption maxima (alpha, beta, and Soret bands) at 601, 556.5, and 435 nm, isospirographis oxymyoglobin at 595, 550, 429 nm, and 2,4-diformyl oxymyoglobin at 603, 563.5, and 447 nm. The optical red shifts as well as the decrease in the oxygen affinities of these myoglobins are attributed mainly to the presence of strongly electron-attractive formyl side chains. Since the free isomers of monoformyl-monovinyl heme have similar properties, the differences observed after recombination with apoprotein must be caused by interactions with apomyoglobins. The degree of such a protein effect may be estimated by comparing the absorption spectra of heme before and after recombination and was found to differ among the various myoglobins. Comparison of the oxygen affinities of the myoglobins taking account of this protein factor showed that the increase in the P50 values are inversely related to that in the pK3 values of the free porphyrins. These results suggest the involvement of pi bonding in determining the oxygen-iron bond strength.     

Copper(II), cobalt(II) and nickel(II) complexes of alkyl-substituted tris(2-benzimidazolylmethyl)amines and their ternary copper(II) systems containing several thiolates

Copper(II), cobalt and nickel(II) complexes of tris(benzimidazolylmethyl)amine(1) and of its methyl(2), isobutyl(3) or isopropyl(4)-substituted derivatives of one of the backbone methylene groups were prepared and characterized. The ligands (1)–(3) afforded trigonal bipyramidal copper(II) complexes, whereas ligand (4) gave a tetrahedrally distorted tetragonal one because of the steric hindrance arising from the isopropyl group. All the cobalt(II) complexes prepared were supposed to be tetrahedral or pseudotrigonal bipyramidal, and all the nickel(II) complexes to be slightly tetrahedrally distorted octahedral. Ternary copper(II) systems containing several thiolates as the third component exhibited intense blue, brown or green color under a reduced temperature by virtue of the charge transfer bands, S^? → Cu.     

A Stopped-Flow Method for the Determination of Ascorbic Acid in Orange Juice Containing Triose Reductone

The adsorption of uranium by chitin phosphate and chitosan phosphate was investigated to obtain information on uranium recovery from aqueous systems, especially sea water and uranium mine waste water. The adsorption of uranium by chitin phosphate and chitosan phosphate was much greater than copper, cadmium, manganese, zinc, cobalt, nickel, magnesium and calcium. The adsorption of uranium was very rapid during the first 10 min and was affected by pH of the solution, temperature, granule radius and the co-existence of carbonate ion. The amounts of uranium adsorbed on the adsorbents increased linearly as the external uranium concentration increased. Uranium adsorbed on chitin phosphate easily desorbed with diluted sodium carbonate solution. On the other hand, uranyl and cobalt ions were separated from each other by using chitin phosphate.     

Influence of soil waterlogging on subsequent plant growth and trace metal content

Summary The uptake of trace metals by two plant species (French bean and maize) has been measured on two soils subjected to various waterlogging regimes. Uptake of both manganese and iron was increased due to soil waterlogging, although reoxidation of the soil affected iron more than manganese. Zinc and copper uptake was influenced by a species factor; French bean (Phaseolus vulgaris) showed preferential uptake of zinc, whereas maize (Zea mays) took up copper preferentially. Uptake of cobalt by both species was increased due to waterlogging, following the pattern of manganese.The abilities of these species to take up trace metals from soil followed the pattern predicted by selective extraction of soil for manganese, iron and cobalt, but not for zinc and copper.     

Trace element uptake by L-cells as a function of trace elements in a synthetic growth medium

The concentration of trace elements in L-cells has been studied as a function of the trace metal content of the growth medium. Cells were cultured in synthetic media which contained varying trace amounts of the elements manganese, iron, cobalt, copper, zinc and molybdenum. The cellular concentration of the elements potassium, iron, copper and zinc were then determined. It was found that the cell accumulates trace metals at a different rate than they are made available. Deficiencies in zinc could be “induced” in the cell by increasing the concentration of iron, manganese and cobalt; cellular iron deficiencies were observed at larger medium concentrations of zinc, manganese, copper and cobalt. Trace metal uptake by the cell was seen to parallel the utilization by multicellular organisms.     

Preparation of artificial 2-, 3-, 4- and 8-domain myoglobins and comparison of their autoxidation rates

Although most hemoglobins and myoglobins consist of 15-kDa single-domain subunits, structurally unusual hemoglobins, such as Artemia 9-domain and Barbatia 2-domain hemoglobins, occur naturally in several invertebrates. These hemoglobins appear to be the result of gene duplication and fusion. Using cDNA coding for the open reading frame of Aplysia kurodai myoglobin, artificial cDNA inserts corresponding to contiguous dimer, trimer, tetramer and octamer myoglobins (2-, 3-, 4- and 8-domain myoglobins) were prepared and cloned into pMAL or pQE plasmids. These artificial myoglobins and wild-type single-domain myoglobins were successfully expressed in Escherichia coli in the heme-attached, oxygenated form. Myoglobin was purified partially by ammonium sulfate fractionation and gel filtration, and autoxidation rates were examined. The autoxidation rates of recombinant wild-type myoglobins with MBP or hexameric His tag were comparable to those of native myoglobin, suggesting that the recombinant proteins appear to be properly folded and that the N-terminal MBP or His tag does not have an affect on the rate. On the other hand, the rates were significantly decreased in the 2- and 3-domain myoglobins (50% and 30% of the single-domain myoglobins, respectively). The rates for 4- and 8-domain myoglobins were similar to those for 3-domain myoglobin. These results indicate that the artificial poly-domain structure of myoglobin is more stable than the usual single-domain myoglobin from the viewpoint of storage of bound dioxygen.     

Nuclear magnetic resonance studies of metal substituted horse cytochrome c

The proton nuclear magnetic resonance spectra of various metal substituted derivatives of horse cytochrome c have been studied and compared to the spectra of native cytochrome c. The proteins studied were the cobalt(III), copper(II), iron(II), iron(III), manganese(III), nickel(II), and zinc(II) derivatives. Spectra of the diamagnetic cobalt(III), iron(II), and zinc(II) proteins were well-resolved and specific resonance assignments were made. All three proteins possessed a methionine ligand to the metal. The spectrum of cobalt(III) cytochrome c was investigated in some detail as this protein was used as a diagmagnetic control for iron(III) cytochrome c. Comparison of the spectra of cobalt(III) and iron(II) cytochromes c revealed that their conformations were very similar but the following conclusion could be made; the oxidation of cytochrome c is accompanied by a small conformation change.     

The diverse chemical forms of heavy metals in tissue extracts of some metallophytes from Shaba Province,Zaïre

Copper and cobalt were determined in tissue extracts of five metallophytes from Shaba Province, Zaïre. About 4O% of the cobalt and copper was extractable into deionized water and a further 4O% was extractable in 0.2M hydrochloric acid. It was concluded that copper and cobalt are bound to several different ligands instead of a single ligand as in the case of nickel hyperaccumulators. Proton microprobe studies on the cobalt accumulator Haumaniastrum robertii showed a strong inverse correlation between the spatial distributions of cobalt and potassium, as well as a direct relationship between cobalt and calcium. It is suggested that some of the cobalt may be immobilized with calcium in oxalate crystals.     

Metals affect the structure and activity of human plasminogen activator inhibitor-1. II. Binding affinity and conformational changes

Human plasminogen activator inhibitor type 1 (PAI-1) is a serine protease inhibitor with a metastable active conformation. The lifespan of the active form of PAI-1 is modulated via interaction with the plasma protein, vitronectin, and various metal ions. These metal ions fall into two categories: Type I metals, including calcium, magnesium, and manganese, stabilize PAI-1 in the absence of vitronectin, whereas Type II metals, including cobalt, copper, and nickel, destabilize PAI-1 in the absence of vitronectin, but stabilize PAI-1 in its presence. To provide a mechanistic basis for understanding the unusual modulation of PAI-1 structure and activity, the binding characteristics and conformational effects of these two types of metals were further evaluated. Steady-state binding measurements using surface plasmon resonance indicated that both active and latent PAI-1 exhibit a dissociation constant in the low micromolar range for binding to immobilized nickel. Stopped-flow measurements of approach-to-equilibrium changes in intrinsic protein fluorescence indicated that the Type I and Type II metals bind in different modes that induce distinct conformational effects on PAI-1. Changes in the observed rate constants with varying concentrations of metal allowed accurate determination of binding affinities for cobalt, nickel, and copper, yielding dissociation constants of ～40, 30, and 0.09 μM, respectively. Competition experiments that tested effects on PAI-1 stability were consistent with these measurements of affinity and indicate that copper binds tightly to PAI-1.     

Mass balance of heavy metal uptake by encapsulated cultures ofKlebsiella aerogenes

Dialysis was employed as a method of speciating heavy metals in cultures of an extracellular polymer forming strain ofKlebsiella aerogenes. A noncapsulated strain of the same bacterium was used as a control, and a mass balance of copper, cadmium, cobalt, nickel, and manganese in batch culture at pH 4.5 and pH 6.8 and in continuous culture at pH 6.8 was constructed. Copper and cadmium were accumulated by the cell during rapid proliferation whereas all 5 metals were bound nonspecifically by extracellular polymer produced during stationary phase and at low dilution rates. The presence of extracellular polymer appeared to inhibit cellular uptake of nickel. At the lower pH, metal uptake was considerably reduced. The results are discussed in the context of metal removal in the activated sludge process of waste water treatment.     

Metal binding and antibacterial activity of ciprofloxacin complexes

Four novel cobalt(II), copper(II), nickel(II) and zinc(II) complexes of the fluoroquinolone antibiotic ciprofloxacin have been prepared. The compounds were characterized by IR, UV-Visible, molar conductivity and elemental analyses. In all of the complexes, the drug ligand, ciprofloxacin (CFL) was coordinated through two carbonyl oxygen atoms. Octahedral and square-planar geometries have been proposed for the cobalt(II), nickel(II) and zinc(II), and copper(II) complexes, respectively. In vitro tests of susceptibility to these metal complexes showed stronger activity than that of ciprofloxacin against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Bacillus dysenteriae.