Showing papers on "Zinc published in 1971"
TL;DR: In different marine organisms, the behaviour of heavy metals is described in terms of their absorption, storage, excretion and regulation when different concentrations are available in the environment.
Abstract: Heavy metals such as copper, zinc and lead are normal constituents of marine and estuarine environments. When additional quantities are introduced from industrial wastes or sewage they enter the biogeochemical cycle and, as a result of being potentially toxic, may interfere with the ecology of a particular environment. In different marine organisms, the behaviour of heavy metals is described in terms of their absorption, storage, excretion and regulation when different concentrations are available in the environment. At higher concentrations, the detrimental effects of heavy metals become apparent and their different toxic effects and factors affecting them are also described.
456 citations
TL;DR: Homogeneous DNA polymerases from E. coli and sea urchins contain zinc in a proportion of approximately 2 and 4 gm atoms Zn/mole enzyme respectively, which suggests that the bound zinc plays a functional role in the interaction of DNA with the polymerases.
235 citations
215 citations
TL;DR: Highly purified preparations of the DNA-dependent RNA polymerase obtained from Escherichia coli contain about 2 g-atoms of tightly bound zinc per mol (molecular weight 370,000) and one or both of the bound zinc atoms may participate in the initiation of RNA synthesis.
Abstract: Highly purified preparations of the DNA-dependent RNA polymerase obtained from Escherichia coli contain about 2 g-atoms of tightly bound zinc per mol (molecular weight 370,000) of enzyme. When the purified enzyme is fractionated on Sephadex G-150 or G-200, correlation is observed between the zinc and enzymic activity. Although some of the preparations examined also contain iron, copper, and magnesium, the content of these metal ions show no consistent correlation with RNA polymerase activity.
Initiation of RNA synthesis is specifically inhibited by 1,10-phenanthroline. Less-effective inhibition is observed for other chelating agents or for a nonchelating phenanthroline analog. The analog also exhibits a pattern of inhibition differing from that characteristic of 1,10-phenanthroline. Binding of purine nucleoside triphosphates at the lower-affinity (Kd = 0.15 mM) site may also be prevented by the addition of 1,10-phenanthroline. One or both of the bound zinc atoms may, therefore, participate in the initiation of RNA synthesis.
192 citations
TL;DR: The equilibrium distribution of copper( II) and zinc(II) ions among a mixture of 17 amino acids has been computed from stability-constant and blood-plasma-composition data and appreciable complex-formation occurs with most of the other amino acids.
Abstract: The equilibrium distribution of copper(II) and zinc(II) ions among a mixture of 17 amino acids has been computed from stability-constant and blood-plasma-composition data. At pH7.4, 98% of the copper(II) in the simulated plasma solution is co-ordinated to histidine and cystine, predominantly as the mixed-ligand complexes [Cu.His.Cystine](-) and [Cu.H.His.Cystine]. Approximately half of the zinc(II) is co-ordinated to cysteine and histidine, but appreciable complex-formation occurs with most of the other amino acids. Stability constants are given for copper(II) and zinc(II) amino acid complexes, including some mixed-ligand species, at 37 degrees C and I=0.15m.
163 citations
147 citations
TL;DR: Stability constants of zinc- and cadmium- glutathione complexes have been obtained from pH titration data for solutions at 37° and 0.15 M in KNO3 and it is suggested that ionization of the peptide linkage can occur on complex formation.
127 citations
122 citations
TL;DR: The lead ion-selective ceramic membrane electrode developed by sintering a mixture of lead, silver, and cuprous sulfides showed sensitivity, selectivity, and other response characteristics well suited to analytical utilization as mentioned in this paper.
Abstract: The lead(II) ion-selective ceramic membrane electrode developed by sintering a mixture of lead, silver, and cuprous sulfides showed sensitivity, selectivity, and other response characteristics well suited to analytical utilization. The Nernstian slope was obtained over a concentration range from 10−1 to 10−6M Pb2+ in activity, and the analytical range had a concentration of 10−1–10−7M when the membrane contained less than 30 wt% of cuprous sulfide and more than 1 wt% of lead sulfide. Among the common ions, silver, cupric, mercury(II), ferric, sulfide and iodide ions interfered seriously. About 10 times as many cadmium and bromide ions and more than 1000 times as many alkali metal, alkaline earth metal, zinc, aluminum, nickel, manganese(II), cobalt, and nitrate ions did not interfere with the lead ion, however. The electrode potentials did not change over a pH range from 2 to the pH at which the precipitation of lead hydroxide occurred. The electrode was safely used at temperatures from 0 to 95°C, and the ...
119 citations
116 citations
TL;DR: It appears that a primary effect of cadmium was to prevent absorption of dietary iron in day-old coturnix birds.
Abstract: This study was designed to evaluate the effects of supplements of individual dietary components in altering the toxicity of dietary cadmium. Day-old coturnix (Japanese quail) were fed 75 mg Cd/kg of an adequate purified diet for 2- or 4-week periods. Cadmium produced moderate growth retardation, severe anemia, decreased ash content of the tibia, and deviations from the normal concentrations of zinc, iron, cadmium, copper, and calcium in one or more of the cells or tissues assayed (erythrocyte, liver, kidney, and tibia). Dietary supplements of zinc, iron(III), copper, and L-cysteine-HCl and injected ascorbic acid produced slight to moderate protection against cadmium-induced anemia, whereas iron(II), ascorbic acid, and D-isoascorbic acid had marked effects in preventing the anemia, growth retardation, poor bone mineralization, and perturbations in elemental concentrations of tissues. Chromium, cobalt, selenium, nickel, molybdenum, and pteroylglutamic acid had no effects. Cadmium did not affect the total ascorbate content of the liver. Removal of dietary ethoxyquin did not affect the toxicity of cadmium or the protective effects of ascorbic acid. Initiation of ascorbic acid feeding at 2 weeks was beneficial to birds fed cadmium throughout the 4-week experiment. Under the conditions of these experiments cadmium produced a functional iron deficiency and less clear-cutmore » affects on zinc function. It appears that a primary effect of cadmium was to prevent absorption of dietary iron. 33 references, 6 tables.« less
TL;DR: Serum ceruloplasmin tended to follow serum copper concentrations, and it is suggested that the regulation of metal binding proteins may be important in the circadian pattern of these metals observed in serum.
Abstract: LIFSCHITZ, M. D., AND R. I. HENKIN. Circadian variation in copper and zinc in man. J. Appl. Physiol. 31(l): 88-92. 1971.~Copper and zinc metabolism were studied in 10 normal volunteers on a constant regimen consisting of an alternate 4 hourly intake of a liquid diet or distilled water, and a regulated amount of activity. Urine was collected in 4-hr periods and blood samples drawn in the middle of these periods. A circadian pattern of variation for serum copper and zinc concentration was demonstrated; serum copper was above the mean at 10 : 00 AM and 2 : 00 PM, at the mean at 6 :00 PM and 10 :00 PM, and below the mean at 2 :00 AM and 6 :00 AM. Serum zinc was above the mean from 10 :00 AM to 10 :00 PM and below the mean at 2 : 00 AM and 6 :00 AM. This pattern persisted in two subjects who received 2.5 mg of prednisolone every 6 hr for 3 days. A circadian pattern for the urinary excretion of copper but not for zinc was demonstrated. Serum ceruloplasmin tended to follow serum copper concentrations, and suggested that the regulation of metal binding proteins may be important in the circadian pattern of these metals observed in serum.
01 Oct 1971
TL;DR: In this paper, a new mechanism for the inhibition reaction between iron and zinc is proposed, where a thin layer of an Fe-AlZn ternary compound forms on the iron surface and inhibits the growth of Fe-Zn phases.
Abstract: The reaction mechanisms and the structures of the phases formed during the hot dipping of iron in 0 to 10 pct Al-Zn alloy baths at temperatures of 450° to 700°C were studied by X-ray diffraction and electron microprobe analysis techniques. A new mechanism for the inhibition reaction between iron and zinc is proposed. At bath temperatures below 600°C, a thin layer of an Fe-Al-Zn ternary compound forms on the iron surface and inhibits the growth of Fe-Zn phases. Breakdown of inhibition occurs during the dipping process when the ternary compound becomes rich in aluminum and transforms to a more stable structure which is isomorphous with Fe2Al5. While this breakdown is occurring, the zinc atoms react with iron and form the conventional Fe-Zn phases.
TL;DR: A new technique in atomic absorption spectroscopy is described, which replaces the use of a flame, and has given excellent results initially when applied to the measurement of magnesium, iron, copper, lead, and zinc in blood and plasma.
Abstract: A new technique in atomic absorption spectroscopy is described, which replaces the use of a flame. Samples are injected into a cavity drilled transversely through a carbon rod, and subsequently dried, ashed, and atomized by the application of electric current. The resulting brief absorption signal is recorded and compared with standards. The procedure is particularly suitable for biological work since sample volume requirements are in the submicroliter range. The samples require no pretreatment. The method has given excellent results initially when applied to the measurement of magnesium, iron, copper, lead, and zinc in blood and plasma.
TL;DR: A result similar to that of Levij and Polliack is achieved by a method diametrically opposite of that of DeWys et al: carcinogenesis in the hamster cheek pouch is inhibited by the administration of additional zinc.
Abstract: WE are prompted by two recent publications to communicate incomplete results of an experiment which is still in progress. Levij and Polliack1 reported the inhibition of chemical carcinogenesis in the hamster cheek pouch by topical application of chlorpromazine; DeWys et al.2 reported the inhibition of Walker 256 carcinosarcoma growth by dietary zinc deficiency. We have achieved a result similar to that of Levij and Polliack by a method diametrically opposite to that of DeWys et al.: we have inhibited carcinogenesis in the hamster cheek pouch by the administration of additional zinc.
TL;DR: The data indicate that there is very minimal storage of readily available zinc in the male rat and Cadmium was localized in liver and kidney but not in testes of the authors' animals.
Abstract: Nutritional zinc can be studied in the male rat as a pharmacologic agent. Responses to zinc in respect to body growth, hematologic effects, blood and tissue levels, and body temperature control are all log-dose related. Copper levels in liver and kidney are influenced by zinc intake. Cadmium alters these responses inversely in relation to the zinc intake, and thus can be considered as an antimetabolite of zinc. Cadmium was localized in liver and kidney but not in testes of our animals. Our data indicate that there is very minimal storage of readily available zinc in the male rat.
TL;DR: The application of zinc-silver oxide batteries is discussed in this article, where the battery use, procurement, quality control, and reliability are discussed, as well as battery design features.
Abstract: : Contents: Zinc electrode, fundamental chemistry and electrochemistry; Silver electrode, fundamental chemistry and electrochemistry; Manufacture of electrodes; Separators; Cell and battery design features; Applications of zinc-silver oxide batteries; and Battery use, procurement, quality control, and reliability.
TL;DR: In this paper, the total concentration of copper, manganese and zinc in 84 samples obtained from 28 stations in the Gulf of Mexico was determined using neutron activation techniques, and it was suggested that this enrichment results from release of trace metals by decomposing organisms.
TL;DR: It is proposed that adequate zinc may be essential for normal tertiary and quaternary structure of the cytoplasmic ribosomes of Euglena.
Abstract: Zinc deficiency in dark-grown Euglena gracilis Klebs, Z strain Pringsheim, results in the disappearance of cytoplasmic ribosomes. In contrast, ribosomes in zinc-sufficient Euglena are conserved, do not undergo turnover, and can be demonstrated at any stage of growth. The zinc content of ribosomes from zinc-deficient Euglena just prior to ribosomal disappearance is 300 to 380 micrograms of zinc per gram rRNA as compared to 650 to 1280 micrograms of zinc per gram rRNA in ribosomes from zinc-sufficient cells. Ribosomal disappearance is believed to involve a generalized disintegration process related to the lower content of zinc in the ribosomes. Reappearance of ribosomes requires the addition of zinc. It is proposed that adequate zinc may be essential for normal tertiary and quaternary structure of the cytoplasmic ribosomes of Euglena.
TL;DR: The localization of 65Zn was examined in cell-free systems extracted from the roots of clones of Agrostis tenuis in further investigations on the mechanism of heavy metal tolerance in this grass species.
Abstract: Summary
The localization of 65Zn was examined in cell-free systems extracted from the roots of clones of Agrostis tenuis in further investigations on the mechanism of heavy metal tolerance in this grass species. The cell wall fraction was a major site for zinc accumulation especially in a zinc-tolerant clone where more zinc accumulated at this site than in non-zinc-tolerant clones. In the absence of the cell wall fraction or when its zinc-binding potential had been reduced, other particulate cellular components accumulated large amounts of zinc. Zinc uptake by the cell wall occurred by the same process in all the clones studied. Uptake was very rapid and independent of temperature and pH, suggesting an exchange adsorption process. A basis for zinc tolerance in A. tenuis is briefly discussed.
TL;DR: Zinc content and RNA/DNA ratios were significantly reduced in the liver, kidney, pancreas, and bone, but DNA per milligram of wet weight remained unaltered in zinc-deficient animals as compared to their pair-fed controls.
TL;DR: Results substantiate the hypothesis that even in the presence of teratogenic zinc deficiency in the fetus, female rats fed a zinc-deficient diet during pregnancy cannot mobilize zinc from body tissues in amounts sufficient to supply the needs of normal fetal develop ment.
Abstract: The effect of pregnancy on the zinc content of maternal bone and liver was determined in rats fed either a zinc-deficient or a zinc-supple mented purified diet. Although the zinc content of fetuses from deficient females was lower than that of fetuses from zinc-supplemented controls, the zinc con tent of maternal liver and bone was not significantly lower at term than that of nonpregnant rats fed the same diet for 21 days. These results substantiate the hypothesis that even in the presence of teratogenic zinc deficiency in the fetus, female rats fed a zinc-deficient diet during pregnancy cannot mobilize zinc from body tissues in amounts sufficient to supply the needs of normal fetal develop ment. J. Nutr. 101: 597-604, 1971.
TL;DR: Anodic stripping voltammetry with a composite graphite-mercury electrode was applied to demonstrate that chitosan can collect naturally occurring zinc, cadmium, lead and copper from sea-water, with high yields.