Showing papers on "Zinc published in 1974"
TL;DR: In this paper, the conversion of light blue colour due to the activity of zinc dependent carbonic anhydrase into yellowish green and greenish yellow was used as an index for zinc deficiency and sufficiency, respectively, in the plant tissues.
Abstract: Fresh leaf discs/pieces of wheat, gram, maize and mustard were incubated in a substrate consisting of 4 ml 0.2M phosphate buffer (pH 6.8), 4 ml 0.2M NaHCO3 and 0.2 ml 0.002% bromthymol blue at 0 to 4°C for 120–240 seconds. The conversion of light blue colour due to the activity of zinc dependent carbonic anhydrase into yellowish green and greenish yellow was used as an index for zinc deficiency and sufficiency, respectively, in the plant tissues. A correlation coefficient value of r=>+0.9 between the different parameters of rapid tissue test and standard enzyme extraction method, indicated the feasibility of using the present method. re]19730724
327 citations
TL;DR: The fluorescent porphyrin in the erythrocytes of patients with lead intoxication or with iron deficiency anemia is zinc protoporphyrins that is bound to globin moieties, probably at heme binding sites.
Abstract: The fluorescent porphyrin in the erythrocytes of patients with lead intoxication or with iron deficiency anemia is zinc protoporphyrin that is bound to globin moieties, probably at heme binding sites.
219 citations
TL;DR: In this paper, the effects of several soil factors on cadmium accumulation by plants were determined, and it was shown that the retaining power of organic matter for Cd is predominately through its CEC property rather than chelating ability.
Abstract: The effects of several soil factors on cadmium (Cd) accumulation by plants were determined. Cadmium concentration in oat shoots (Avena sativa L.) was decreased by increasing the cation exchange capacity (CEC) of the soil. Except for its CEC effect, organic matter did not influence the concentration of Cd in oat shoots. The results indicate that the retaining power of organic matter for Cd is predominately through its CEC property rather than chelating ability. Cadmium concentration of soybean shoots (Glycine max L.) increased soil temperature. In the presence of 10 ppm of soil-applied Cd, the addition of Zn from the 5 to 50 ppm range, apart from raising the Zn concentration, significantly increased the Cd concentration of soybean shoots. The increased Cd concentration was primarily due to decreased plant growth. A depression in Cd concentration of soybean shoots, relative to control, began to occur at the 100 ppm Zn level. 12 references, 5 tables.
208 citations
193 citations
TL;DR: Taurine, a nonessential amino acid, can decrease seizures in a variety of animal species and is particularly effective against ouabain-induced seizures in rats.
Abstract: Recent experiments from our laboratory and others demonstrate that sodium-potassium-adenosine triphosphatase inhibition, particularly in the hippocampus, is involved in epileptogenicity. Zinc ions can mimic ouabain when injected intraventricularly and can produce epileptic seizures in rats; serum zinc levels in treated epileptics are significantly decreased as compared to age- and sex-matched controls. Taurine, a nonessential amino acid, can decrease seizures in a variety of animal species and is particularly effective against our model of ouabain-induced seizures in rats. Preliminary experiments in human epileptic subjects confirm the anticonvulsive effect of taurine. These results justify controlled therapeutic trials of taurine and detailed biochemical studies of zinc metabolism in human epilepsy.
191 citations
TL;DR: It is concluded that the cobalt atom is coordinated in a distorted tetrahedral geometry, consistent both with those other cobalt-substituted zinc enzymes which exhibit similarly unusual properties as compared with Co(II) complex ions and with interpretations of x-ray structure analysis of native thermolysin.
170 citations
TL;DR: ThePurification and characteristics of this enzyme are described and the evolutionary implications of the presence in procaryotes of this kind of superoxide dismutase (formerly characteristic of eucaryotes) are discussed.
161 citations
TL;DR: The results demonstrate a clearly defined stimulus to growth brought about by supplementation with zinc when adequate amounts are given, and a tendency toward accelerated sexual development in the zinc supplemented boys was evident.
141 citations
131 citations
TL;DR: The algicidal and algistatic effects of copper, zinc and cadmium on Selanastrum capricornutum, a unicellular green algae were analyzed by using a modification of the Algal Assay Procedures Bottle Test as discussed by the authors.
01 Jan 1974
TL;DR: In this article, two postassay treatments were found that markedly enhanced the extent of nitrite color formation and apparent nitrate reductase activity and showed that the zinc acetate removes extract factor(s) that interfere with color development, because it does not remove the NADH.
Abstract: Nitrate reductase activity is most commonly assayed by measurement of product formation. Excess NADH and factor(s) present in the enzyme extract that interfere with the diazotization and azo color complex of nitrite cause a depression of apparent nitrate reductase activity. Two postassay treatments were found that markedly enhanced the extent of nitrite color formation and apparent nitrate reductase activity. The procedure involves stopping the reaction with zinc acetate (50 ,umoles per ml of reaction mix), followed by removal of the precipitate by centrifugation. Presumably the zinc acetate removes extract factor(s) that interfere with color development, because it does not remove the NADH. Phenazine methosulfate (15 nmoles per ml of reaction mix) is added to aliquots of the supernatant and allowed to stand for 20 min at 30 C to oxidize the residual NADH before color development.
TL;DR: Two clones of Skeletonema costatum studied showed significant intraspecific differences regarding the tolerance to zinc pollution, and Dialysis bioassay was found suitable for monitoring heavy metal pollution of aquatic recipients.
Journal Article•
TL;DR: There was a further depression of plasma zinc levels and an elevation of copper levels in late pregnancy and an increase in plasma chromium concentration after an oral glucose load was detectable in only 33% of subjects tested during late pregnancy.
TL;DR: The results have been interpreted in terms of the role the protein may play as a calcium storage site and in reducing the permeability of the sarcoplasmic reticulum.
TL;DR: Zinc ion inhibits the posttranslational cleavages of human rhinovirus-1A, encephalomyocarditis virus, and poliovirus polypeptides, and the relative position of their gene loci on the viral RNA was determined and these data were used to place them in the over-all scheme of viral protein processing.
Abstract: Zinc ion inhibits the posttranslational cleavages of human rhinovirus-1A, encephalomyocarditis virus, and poliovirus polypeptides. Each virus displayed a different susceptibility to zinc. However, in each case the cleavages of the capsid precursor and the cleavages analogous to the C --> D --> E conversion in encephalomyocarditis virus were most sensitive to zinc. Higher concentrations of zinc resulted in the buildup of even larger precursor polypeptides of a size between 106,000 and 214,000 daltons. The sizes of these polypeptides and the relative position of their gene loci on the viral RNA were determined. These data were used to place these polypeptides in the over-all scheme of viral protein processing.
TL;DR: The results of this study are shown to be consistent with the Copper-zinc superoxide dismutase binding site being a distorted square planar arrangement of ligands and neighboring the zinc-binding site.
TL;DR: In this paper, the concentrations of the trace metals have been established in the open-ocean waters, and have been used as "baselines" to evaluate trace-metal enhancement in near-shore regions.
TL;DR: The data presented indicate that the ability of molluscs to accumulate certain metals, particularly zinc and cadmium, to abnormally high levels is not shared by finfish species, which means that the monitoring of commercial fish species caught in the River Derwent would provide a much less sensitive index of pollution than would the Monitoring of oysters or mussels.
Abstract: Thirty-nine marine species, including members of the Teleostorni and Elasmobranchii, were obtained from the River Derwent and analysed for four heavy metals known to be accumulated by certain species, particularly molluscs. Of the muscle tissues from edible Teleostomi and Elasmobranchii all contained levels of zinc, cadmium, and copper well below the maximum levels permitted by current Tasmanian food regulations. Manganese levels were also low. Small species differences for zinc and copper levels in muscle tissue are evident among these finfish. These are probably attributable to differences in feeding habits. Comparison of the metal levels in these species with levels reported by various overseas workers indicate no abnormal accumulation of heavy metals in muscle tissues. With some minor exceptions no relationships existed between the tissue metal levels and length of the fish. Two edible species of molluscs, the native oyster and the common mussel, contained much higher levels of the four metals. For both species levels of zinc and cadmium exceeded the levels specified by the food regulations. The data presented indicate that the ability of molluscs to accumulate certain metals, particularly zinc and cadmium, to abnormally high levels is not shared by finfish species. The fact that elevated metal concentrations in seawater are not reflected in the muscle tissues of finfish means that the monitoring of commercial fish species caught in the River Derwent would provide a much less sensitive index of pollution than would the monitoring of oysters or mussels.
01 Jan 1974
TL;DR: In this paper, the effects of internally applied divalent cations on the ionic currents of voltage-clamped squid giant axons were studied and the effect of internal concentra- tions of calcium up to 10 mM had little, if any, effect on the time-course, voltage dependence, or magnitude of the ionIC currents.
Abstract: We have studied the effects of internally applied divalent cations on the ionic currents of voltage-clamped squid giant axons. Internal concentra- tions of calcium up to 10 mM have little, if any, effect on the time-course, voltage dependence, or magnitude of the ionic currents. This is inconsistent with the notion that an increase in the internal calcium concentration produced by an inward calcium movement with the action potential triggers sodium inactiva- tion or potassium activation. Low internal zinc concentrations (N1 mM) selec- tively and reversibly slow the kinetics of the potassium current and reduce peak sodium current by about 40 % with little effect on the voltage dependence of the ionic currents. Higher concentrations (10 mM) produce a considerable (ca. 90 %) nonspecific reversible reduction of the ionic currents. Large hyperpolariz- ing conditioning pulses reduce the zinc effect. Internal zinc also reversibly de- polarizes the axon by 20-30 mV. The effects of internal cobalt, cadmium, and nickel are qualitatively similar to those of zinc: only calcium among the cations tested is without effect.
TL;DR: The dehydrogen enzyme activity measured by a modified TTC-test correlates fairly well with oxygen-uptake and toxic substances such as zinc, phenol, cyanide and 2-4D do not influence the oxygen uptake and dehydrogenase activity to the same extent.
TL;DR: The present data show that this protein is a zinc metalloenzyme demonstrating the postulated relationship between zinc and a leukemic process, and underline the participation of zinc in nucleic acid metabolism and bear importantly upon the lesions that accompany leukemia and zinc deficiency.
Abstract: RNA tumor viruses contain a characteristic RNA-dependent DNA polymerase (reverse transcriptase) which has been thought to be related to the induction of leukemia by this virus. A disturbance in a zinc-dependent enzyme system was first postulated to account for the demonstrated differences in zinc metabolism of normal and leukemic leukocytes [Vallee et al. in (1949) Acta Unio. Int. Contra Cancrum 6, 869 and (1950) Acta Unio. Int. Contra Cancrum 6, 1102]. In order to investigate the relationship between zinc and the initiation of leukemia in chickens by avian myeloblastosis virus, we have examined the metalloenzyme nature of its reverse transcriptase. The present data show that this protein is a zinc metalloenzyme demonstrating the postulated relationship between zinc and a leukemic process. Paucity of purified enzyme generated the design of a novel system of analysis incorporating microwave-induced emission spectrometry combined with gel exclusion chromatography. It provides precision, reproducibility, and remarkable limits of detection on μl samples containing 10-12 to 10-14 g-atoms of metal, and is thus orders of magnitude more sensitive than other methods. The chromatographic fraction with highest enzymatic activity contains 1.8 × 10-11 g-atoms of zinc per 1.6 μg of protein, corresponding to either 1.8 or 2.0 g-atoms of zinc per mole of enzyme for a molecular weight previously determined either as 1.6 or 1.8 × 105. Copper, iron and manganese are absent, i.e., at or below the limits of detection, 10-13 to 10-14 g-atoms. Agents known to chelate zinc inhibit the enzyme, while their nonchelating isomers do not. The data underline the participation of zinc in nucleic acid metabolism and bear importantly upon the lesions that accompany leukemia and zinc deficiency.
TL;DR: The effects of internal cobalt, cadmium, and nickel are qualitatively similar to those of zinc: only calcium among the cations tested is without effect.
Abstract: We have studied the effects of internally applied divalent cations on the ionic currents of voltage-clamped squid giant axons. Internal concentrations of calcium up to 10 mM have little, if any, effect on the time-course, voltage dependence, or magnitude of the ionic currents. This is inconsistent with the notion that an increase in the internal calcium concentration produced by an inward calcium movement with the action potential triggers sodium inactivation or potassium activation. Low internal zinc concentrations (∼1 mM) selectively and reversibly slow the kinetics of the potassium current and reduce peak sodium current by about 40% with little effect on the voltage dependence of the ionic currents. Higher concentrations (∼10 mM) produce a considerable (ca. 90%) nonspecific reversible reduction of the ionic currents. Large hyperpolarizing conditioning pulses reduce the zinc effect. Internal zinc also reversibly depolarizes the axon by 20–30 mV. The effects of internal cobalt, cadmium, and nickel are qualitatively similar to those of zinc: only calcium among the cations tested is without effect.
TL;DR: The partially loaded Cu-thionein was expected to polymerize via disulphide bridges in the presence of oxygen to form the ‘neonatal type’, which was highly interested in the possibility of a direct conversion of metallothionein into Cu- thionein.
TL;DR: In this paper, hundreds of oysters and mud samples from 15 sites along the Tamar River were analysed for cadmium, copper, zinc, lead, lead and chromium.
TL;DR: In this article, the photoluminescence excitation and emission spectra of zinc selenide doped with copper or chlorine have been measured, and it has been shown that at 85 °K the self-activated emission band lies at 6150 A, whereas the copper-red emission occurs at 6400.