Detection of sulfur-containing compounds in control and cadmium-exposed rat organs by high-performance liquid chromatography--vacuum-ultraviolet inductively coupled plasma-atomic emission spectrometry (HPLC-ICP)

Sulfur-containing compounds in biological samples were separated by high-performance gel permeation chromatography and detected with a vacuum-ultraviolet inductively coupled plasma-atomic emission spectrometer. Distribution profiles of sulfur in the supernatants of liver, kidney, spleen, lung, and pancreas of control and cadmium-exposed rats were determined along with cadmium, copper, iron, phosphorus, and zinc profiles. Changes in sulfur distribution were induced by cadmium exposure not only in the metallothionein fraction, but also in the high-molecular-weight protein fraction, indicating the effect of cadmium exposure on diverse endogenous sulfur-containing compounds. Glutathione and taurine also were detected simultaneously as distinct peaks.     

Postinductive actinomycin D effects on the concentrations of cadmium thionein, zinc thionein, and copper chelatin in rat liver

The time courses of induction in rat liver of copper chelatin by copper, cadmium thionein by cadmium, and zinc thionein by copper, cadmium, and zinc were monitorg metal were used in order to avoid toxic effects, being 5 mg zinc, 0.5 mg copper, and 0.25 mg cadmium per kg body weight. Peak times of induction and half times of decay observed were: copper chelatin (9 h, 8.6 h), cadmium thionein (18 h, 6.80 days), and zinc thionein (zinc rats, 18 h, 10.1 h; copper rats, 9 h, 18.2 h; cadmium rats, 24 h, 4.53 days). Administration of actinomycin D (1 mg per kg body weight) at the peak times of induction of the various proteins had no effect on the concentrations of chelatin or cadmium thionein observed up to 24 hours later, but in the case of zinc thionein, induced by zinc, copper, or cadmium, elevated concentrations were observed up to 23 h after administration of the drug. Such behavior is reminiscent of superinduction previously seen with other proteins and enzymes. We postulate that the intracellular concentration of free zinc in liver is of fundamental importance in the induction of zinc thionein, and this can be distributed by exogenous copper or cadmium resulting in the induction of synthesis of zinc thionein.     

Difference in relative isometallothionein ratio between adult and larva of cadmium-loaded bullfrog Rana catesbeiana

Cadmium (Cd) was injected intramuscularly into adults (male) and larvae of the bullfrog, Rana catesbeiana. The chemical forms of Cd in the livers and the effect on several essential metal levels were determined by high performance liquid chromatography-atomic absorption spectrophotometry and inductively coupled plasma-atomic emission spectrophotometry, respectively. Metallothionein which binds cadmium, zinc and copper was induced in the liver and kidney of the adult bullfrog, and the protein was a mixture of two isoforms in both tissues. Although the two isoforms were also induced in the liver of the larva (tadpole), the relative ratio was the reverse of that in the adult.     

Uptake of six heavy metals by oat as influenced by soil type and additions of cadmium,lead, zinc and copper

Summary The influence of heavy metal additions on availability and uptake of cadmium, lead, zinc, copper, manganese and iron by oat was studied. The experiments were carried out as pot experiments using sandy loam, sandy soil and organic soil. Selective extractants were used to remove metals held in different soil fractions.Lead and copper were preferently bound by organics and oxides, zinc by oxides and inorganics, and cadmium by inorganics and organics.Addition of cadmium to the soils resulted in higher cadmium concentrations in all plant parts but lower concentrations of lead, zinc, copper, manganese and iron, and the accumulation indexes of these metals were also lower when cadmium was added to the soil.Addition of cadmium plus lead, zinc and copper resulted in higher cadmium concentrations in leaves and straw of plants grown in sandy loam and sandy soil, but lower concentrations when plants were grown in organic soil as compared with the results when cadmium was added separately. The transfer of cadmium, lead, zinc and copper from soil to plant was greatest from sandy soil, and zinc and cadmium were more mobile in the plant than were lead and copper.Cadmium concentrations in leaves correlated significantly with CaCl₂ and CH₃COOH extractions in sandy loam and sandy soil and with CH₃COOH extractions in organic soil.Generally, the total metal uptake was lowest from organic soil.     

Specificity of zinc binding to myelin basic protein

Z²⁺ appears to stabilize the myelin sheath but the mechanism of this effect is unknown. In a previous report we have shown that zinc binds to CNS myelin basic protein (MBP) in the presence of phosphate and this results in MBP aggregation. For this paper we used a solid phase zinc blotting assay to identify which myelin proteins bind zinc. MBP and a 58 kDa band were found to be the major targets of⁶⁵Zn binding. Moreover, using fluorescence, light scattering and electron microscopy we investigated the binding of zinc and other cations to purified MBP in solution. Among the cations tested for their ability to interfere with the binding of zinc, the most effective were cadmium, mercury and copper, but only cadmium and mercury increased the scattering intensity, whereas MBP aggregation was not inhibited by copper ions. Thus, the effect of zinc on the formation of MBP clusters seems to be specific.     

Induction of metallothionein synthesis in Menkes' and normal lymphoblastoid cells is controlled by the level of intracellular copper

A study was carried out on the uptake of copper, zinc, or cadmium ions and their induction of metallothionein synthesis in Menkes' and normal lymphoblastoid cells. The main difference between Menkes' and normal cells in the uptake of these metal ions was an increased uptake of copper ions in Menkes' cells at a low concentration of CuCl2 (2.1 microM). The CuCl2 concentration necessary to induce metallothionein synthesis in Menkes' cells was 50 microM, whereas that in normal cells was about 200 microM. The levels of zinc or cadmium ions needed to induce metallothionein in Menkes' cells were similar to those in normal cells. At least four isomers of metallothionein were induced by copper, zinc, and cadmium ions in both types of cells. Metallothionein synthesis in Menkes' and normal cells was induced when the amounts of intracellular copper reached a threshold level of approximately 0.2 nmol/10(6) cells, and the rate of metallothionein synthesis in these cells was increased as a function of the amounts of intracellular copper (0.2-1.7 nmol/10(6) cells). These results indicate that the induction of metallothionein synthesis in lymphoblastoid cells is controlled by the level of intracellular copper, suggesting that the major defect in Menkes' cells is not due to the abnormal regulation of metallothionein synthesis but to an alteration of the copper metabolism in cells by which the levels of intracellular copper become larger than those in normal cells and just lower than the threshold level for induction of metallothionein synthesis.     

Heavy metal composition of polysomal fractions following cadmium challenge

Endogeneous levels of zinc and copper were found to be 1.2±0.1×10⁻² and 0.3±0.1×10⁻² μg/A260 unit, respectively, in polysomal fractions from control animals; cadmium, however, was undetectable. In experimental animals (injected with cadmium) zinc, copper, and cadmium were found in polysomal fractions isolated by two different methods. One hour after a cadmium injection there was a rise in both the zinc and copper content of the polysomal fractions, which then declined steadily to below control levels by 16 h. Neither zinc nor cadmium were dialyzable from these fractions by a TRIS buffer; however, addition of 0.01M EDTA to the buffer resulted in removal of 75% of the zinc and all of the detectable cadmium. The addition of cadmium (CdCl₂) to control supernatants (adjusted to the cadmium concentration present in supernatants 6 h after in vivo exposure) resulted in metal binding to polysomal fractions in levels comparable to those observed after in vivo exposures to the metal. When cadmium was added in the form of cadmium thionein, a smaller fraction of the metal was isolated with the polysomal fraction. Cadmium bound to polysomal fractions in vivo (24 h after exposure) was sensitive to release by protease digestion, but insensitive to release by ribonuclease digestion.     

铜、镉胁迫下施硫肥和有机肥对冬小麦碳氮运转的影响

采用盆栽试验,研究了铜、镉胁迫条件下施硫和有机肥对冬小麦碳氮运转的影响。结果表明,与各自对照相比,铜、镉胁迫下低施硫和有机肥的处理增加了小麦叶片、茎鞘、颖壳穗轴等营养器官花前贮藏物质、氮素的再运转量和运转率以及营养器官花前贮藏物质、氮素的总再运转量和总运转率,高施硫和有机肥的铜、镉处理则规律性不明显。在铜、镉胁迫条件下,施用硫肥和有机肥处理增加了小麦成熟期籽粒重和花后光合同化物输入籽粒量以及籽粒氮素含量和花后氮素积累量。与各自对照相比,铜胁迫下施硫和有机肥的处理与镉胁迫下低施硫和有机肥的处理增加了成熟期小麦的穗数、穗粒数和千粒重,提高了籽粒产量,其中以T\-5处理增产幅度最大;镉胁迫下高施硫和有机肥的处理则变化不大。铜、镉胁迫下低施硫和有机肥的处理均增加了籽粒淀粉含量,而高施硫和有机肥的铜、镉处理则未表现出此规律。此外,铜、镉胁迫下施硫和有机肥的各处理增加了籽粒蛋白质的含量。     

Role of S-adenosyl-L-methionine in potentiating cadmium mobilization by diethylenetriamine penta acetic acid in mice

The beneficial effects of S-adenosyl-L-methionine (SAM) in potentiating the mobilization of cadmium by cadmium trisodium diethylenetriamine penta acetic acid (DTPA) from the major target organs and restoration of depleted tissue glutathione (GSH), zinc and copper concentration, were determined in cadmium-exposed mice. The results indicated a significant depletion of cadmium concentration from the blood in DTPA plus SAM treated animals compared with DTPA or SAM alone treated groups. The treatment with SAM alone was also effective in correcting the zinc and GSH concentrations. The results indicated few beneficial effects of concomitant SAM administration during chelation of cadmium with DTPA.     

Effects of zinc, copper, and selenium on placental cadmium transport

The objective of the present study was to evaluate the potential effects of zinc, copper, and selenium on placental cadmium transport. From November 2002 through January 2003, a total of 47 healthy pregnant women from Da-Ye City, Hubei Province in Central China participated in the study. Their age, parity, gestational age, pregnancy history, and lifestyle data were obtained by questionnaire interview. The placental, whole-blood, and cord blood levels of cadmium were determined by inductively coupled plasma mass spectrometer (ICP-MS), whole-blood zinc was measured by flame atomic absorption spectrometry (F-AAS), whole-blood copper by ICP-MS, and selenium was by atomic fluorescence spectrophotometry (AFS). The cord blood cadmium concentration (0.020-1.48 microg/L) was significantly lower than in maternal blood (0.80-25.20 microg/L, p<0.01). The placental cadmium concentration was from 0.082 to 3.97 microg/g dry weight. Multiple linear regression analysis indicated that lower levels of maternal blood copper were significantly associated with higher cadmium concentrations in cord blood. Placental cadmium in women with lower levels of maternal blood zinc was significantly higher than in those with normal zinc levels. The placental cadmium level in women with lower whole-blood selenium was significantly lower than in subjects with normal selenium levels. It was concluded that the essential elements copper, selenium, and zinc might significantly affect placental cadmium transport.     

Heavy metal complexation in polluted molluscs I. Limpets (Patella vulgata and Patella intermedia)

The accumulation of cadmium, zinc and copper by the marine gastropod molluscs Patella vulgata and Patella intermedia has been studied by gel permeation chromatography of water-soluble extracts of environmentally contaminated shellfish.A major proportion of the water-soluble cadmium and copper in these molluscs is associated with a protein of molecular weight 10 800 daltons. Evidence is presented supporting the similarity of this protein with mammalian metallothionein. This protein contained only a small proportion of the zinc found in the samples.     

The tissue disposition and urinary excretion of cadmium, zinc, copper and iron, following repeated parenteral administration of cadmium to rats.

The effect of repeated parenteral administration of cadmium (0.75, 1.5 and 3.0 mg/kg) on tissue disposition and urinary excretion of cadmium, zinc, copper and iron has been studied in the male rat. Cadmium, zinc and copper accumulated in liver and kidney, but the concentration of iron did not alter significantly. The kidney weight relative to body weight showed a dose-related increase in weight of 25--65%. Excretion of cadmium in the urine increased directly with dosage and the increase was most significant when kidney damage had probably occurred. Administration of cadmium also resulted in dose-related increases in the urinary excretion of zinc, copper and iron. The cadmium concentration of blood increased with dosage of cadmium, and the plasma concentrations of zinc and copper were also raised but plasma iron concentration was diminished.     

Hepatic metallothioneins in two neotenic salamanders,Proteus anguinus and Necturus maculosus (Amphibia,Caudata)

The presence of metallothionein (MT) and the subcellular distribution of copper, zinc and cadmium were investigated in livers of two neotenic salamanders, Proteus anguinus and Necturus maculosus. In P. anguinus, caught in the wild, hepatic MTs were present as a single isoform of (Zn, Cu, Cd)-thioneins, whose molecular weight was estimated to be approximately 12000 by size exclusion chromatography. The percentage of zinc and cadmium was higher in the cytosol and of copper in the pellet. Cytosolic cadmium was almost exclusively associated with MTs (80%), while zinc and copper were also present in the regions of higher-molecular weight proteins. In laboratory bred N. maculosus, MTs were isolated from the liver cytosol and extract of the pellet as (Cu, Zn)- and (Zn, Cu)-thioneins, respectively. According to the low amount of copper extracting from liver pellets of N. maculosus, the presence of water insoluble aggregated forms of Cu-thioneins should be checked in further investigations.     

Cadmium and lead toxicity effects on zinc, copper, nickel and iron distribution in the developing chick embryo

The teratologic effects on chicken embryos induced by the load of 100 micrograms of cadmium or lead nitrate salts injected into the yolk on day 5 of incubation as well as their effects upon zinc, copper, nickel and iron distribution were studied. Despite a significant teratologic influence of lead, cadmium administration did not induce significant effects. A week after injections, embryo lead content, but not cadmium concentration, increased; this differential action suggested an active uptake of lead by the embryo, not observed for cadmium. Both cadmium and lead affected significantly the iron, copper and zinc homeostasis in the egg. Cadmium induced these changes probably through alterations in the metallic ion transport processes towards the embryo.     

A comparison of the sequestration of cadmium and zinc in the tissues of rainbow trout (Salmo gairdneri) following exposure to the metals singly or in combination

Rainbow trout were exposed to either cadmium (9 micrograms/l) or zinc (100 micrograms/l) in their aquarium water. They were then transferred to water containing concentrations of cadmium (54 micrograms/l) that would have otherwise proved fatal to the majority of the fish without the pretreatment. Most of the fish survived under both sets of conditions. However, two different mechanisms seem to be involved in the protection of the animals against the toxic manifestations of cadmium. In both cases, more than 99% of the total body load of cadmium was found in the liver, kidney and gills of the animals. Analysis of the metal-binding proteins in these organs was carried out. In the fish exposed to the two concentrations of cadmium, the toxic metal was found only in association with two low mol. wt specific binding proteins despite the presence of zinc- (and copper)-containing isometallothioneins in all three organs. On the other hand, cadmium was distributed between these binding-proteins and metallothioneins in the liver, kidney and gill of the trout pretreated with zinc before their exposure to cadmium.     

Metallic Elements in Hair as a Biomarker of Human Exposure to Environmental Pollution: A Preliminary Investigation in Hubei Province

Metallic elements in hair were assessed in human subjects randomly sampled from six villages in Hubei province, PR China, known to differ in industrial pollution. Metallic elements assessed included copper, zinc, lead, and cadmium. Subjects sampled included adults and children of both sexes. Soil and rice samples from the villages were also examined for contents of metallic elements. Soil and rice contents of copper, lead, and cadmium were higher in the villages closer to the pollution source (copper smeltery). Hair contents of copper, lead, and cadmium were higher in subjects from the polluted villages compared with subjects from the nonpolluted areas. No differences were found in hair zinc content among the villagers. Cadmium contents in rice and human hair were linearly correlated. For lead and copper a logarithmic relation was found. No difference was found between the two genders with respect to hair metallic contents. With regard to age, hair cadmium content was highest in the older age groups in the polluted villages and may reflect chronic exposure. No other systematic age effects were observed. It was concluded that contents of cadmium, lead, and copper in human hair do reflect the degree of environmental pollution.