Copper Supply Research Articles

Enzymic diagnosis of copper deficiency in subterranean clover. II. A simple field test

A rapid, simple and robust field test is described for diagnosing copper deficiency in subterranean clover plants by measuring ascorbate oxidase activity in young folded leaf blades (YFL) homogenized in phosphate buffer. The test measures activity by counting the drops of iodine required to titrate, to a dark blue end-point, excess ascorbic acid added to and incubated for 20 min with a YFL homogenate. When reagent control titrations had titres of 11 drops of iodine, YFL homogenates from copper-adequate plants had titres of 2-3 drops, from copper-deficient plants 6-11, and from plants with marginal copper supply 4-5 drops. The test was standardized against the measurement of ascorbate oxidase activity in YFL by oxygen uptake. Ascorbate oxidase activity was remarkably insensitive to assay temperature, decreasing by only one-third with decreasing temperature from 30 to 10�C. It was also very stable in both homogenates and whole leaves. At room temperature, activity dropped by only 25% in homogenates after 6 h and in whole leaf blades after 48 h. When stored in ice, leaf blades retained full activity for at least 5 days. Diagnosis of copper deficiency by the new test agreed closely with diagnosis based on copper analysis of young open leaves taken from the same subterranean clover plants in field pastures. The test should allow extension workers to give on-the-spot advice about the copper status of pastures containing subterranean clover.

The competitive position of Canadian copper supply

The author examines the proposition that the Canadian copper industry has reached a mature, less competitive, stage of growth. Employing a break-even-cost approach, he compares the Canadian industry to those of other copper-producing nations in terms of cost competitiveness and prospects for new entrants. He finds little evidence to support the proposition, and concludes that Canada's copper industry will continue to maintain its strong competitive position during the 1980s.

EFFECT OF COPPER DEFICIENCY ON PHENOLIC AND OTHER CONSTITUENTS OF WHEAT CELL WALLS

SummaryBefore decreasing yield significantly, copper deficiency affected the amounts of phenolic compounds released (by treatment with sodium hydroxide) from the cell walls separated from young leaves of wheat. Effects of changes in copper supply on the amounts of phenolic compounds released followed closely its effect on copper concentration in the plant parts. More ferulic and less p‐icoumaric acid was released from the walls of young leaves of copper‐deficient plants than from those of copper‐adequate ones; these differences were less marked in older than in younger leaves. Copper deficiency decreased the lignin, hemicellulose and acetyl contents of cell walls only in severely deficient plants.

Male Sterility and Anther Wall Structure in Copper-deficient Plants

Anther development and pollen sterility were followed in plants of wheat, oat, barley, sweetcorn, sunflower, petunia and subterraneum clover grown at a range of copper supplies. Copper-deficient plants had increased pollen sterility. Lignified wall thickenings were reduced or absent in the endothecia of anthers from Cu-deficient plants. Reduced seed set may result both from reduced pollen fertility or failure of the stomia to rupture due to decreased lignification of anther walls.

US copper supply : An economic/engineering analysis of cost—supply relationships

The authors present short- and long-term supply schedules for the primary US copper industry. These schedules are based on the economic theory of supply, and are derived from site- and input-specific cost data. Cost figures are arrived at by a combination of engineering process analysis and statistical cost estimation. The supply functions can be used to evaluate the effects of changes in market, policy, or other variables on US copper supply.

Clostridia colonization and clostridial toxin in neonatal necrotizing enterocolitis

produce clinical copper deficiency (except for a lower hematocrit at six months) in premature infants fed much lower copper intakes. This study suggests the age at which infants of different gestations can be expected to have an increase in serum copper and ceruloplasmin concentrations. Infants past that age (after 3 months in most very premature infants) who have very low serum copper concentrations may be copper deficient, especially if clinically compatible, and may benefit from additional copper supplies. Prior to that time, serum copper and ceruloplasmin values are probably inadequate indicators of total body copper status, and the benefit to risk ratio of copper supplementation is not established. In the great majority of infants, serum copper concentrations will rise spontaneously as either the liver, gastrointestinal tract, or both, mature.

Copper nutrition of subterranean clover (Trifolium subterraneum L. cv. Seaton Park). II. Effects of copper supply on distribution of copper and the diagnosis of copper deficiency by plant analysis

The effect of copper supply upon the distribution of copper within Seaton Park subterranean clover was examined from early vegetative growth to plant maturity in one glasshouse experiment, and in a second experiment was assessed at early flowering. The copper content of old leaf blades of copper-adequate plants decreased progressively with senescence of the blades. Copper deficiency delayed senescence and export of copper from the older blades so that both the relative and net changes were substantially smaller than for blades of copper-adequate plants. However, copper concentrations in senesced old leaf blades still reflected copper supply. At full senescence these blades contained appreciable quantities and concentrations of copper which contrasted with the low levels found in senesced leaves of wheat and peanuts in previous studies. Copper concentration in whole plant tops was not satisfactory for diagnosing copper deficiency, since the critical concentration decreased with plant age and during late vegetative development 'Piper-Steenbjerg' curvature developed in the relationship between copper concentration and yield. It is possible that the curvature resulted partly from unusually high concentrations of copper in the old petioles of severely deficient plants. Analysis of copper in young leaf blades provided a sensitive means of diagnosing copper deficiency in subterranean clover. The estimated critical concentration for these blades (3 �g/g for maximum growth) did not change with plant age, at least until early flowering. In early growth, the copper concentration of young leaf blades may be used to forecast impending copper deficiency.

Copper nutrition of subterranean clover (Trifolium subterraneum L. cv. Seaton Park). I. Effects of copper supply on growth and development

Effects of severe and moderate copper deficiency on the development of leaves and lateral branches, on the distribution of dry weight within the plant, and on seed yield of Seaton Park subterranean clover were assessed as part of three glasshouse experiments. Copper deficiency markedly depressed top and root growth without producing any distinctive symptoms. It retarded phasic development by delaying development of leaves and lateral branches, senescence of plant parts, and flowering: it also depressed the proportion of stem plus petiole in plant tops and decreased internode elongation, pollen fertility and the number of burrs and seeds formed. As a result of its effect in delaying flowering, copper deficiency would depress seed production particularly strongly when low soil water supply shortens the growing season. The need for suitable procedures for diagnosing copper deficiency is emphasized by the lack of specific plant symptoms in this species.

Copper nutrition of subterranean clover (Trifolium subterraneum L. cv. Seaton Park). III. Effects of phosphorus supply on the relationship between copper concentrations in plant parts and yield

The effects of phosphorus supply on the relationship of copper supply with copper concentrations in various plant parts and yield of Seaton Park subterranean clover were examined. Plants were grown in a glasshouse for 40 and 74 days in pots with four levels of potassium phosphate (0, 13, 39, 65 mg phosphorus/pot) and six levels of copper sulfate (0, 50, 100, 200, 400, 800 pg copper/pot) added, in factorial combination, to a sand deficient in both phosphorus and copper. By increasing the phosphorus levels copper deficiency was induced partly by promoting growth and diluting copper concentrations in plants; and also by depressing copper absorption. Increasing phosphorus changed the distribution of copper in plant tops and the shape of curves relating copper concentration in whole plant tops to yield. At 39 mg phosphorus/pot, the relationship at Day 74 had a marked 'Piper-Steenbjerg' curvature, largely as a result of unusually high copper concentrations in the stems plus petioles of severely copper-deficient plants. At 65 mg phosphorus/pot, the relationship had no 'Piper-Steenbjerg' curvature for whole tops and only a relatively small curvature for stems plus petioles. The data suggests that 'Piper-Steenbjerg' curves in subterranean clover result primarily from high concentrations of copper in the stems plus petioles of severely deficient plants. At both harvests, young leaf blades had critical copper concentrations of around 3 �g copper/g at both 39 and 65 mg phosphorus/pot. However, copper-deficient plants with severe phosphorus deficiency did not respond to copper, and generally had copper concentrations below this critical level in all plant parts. The results confirm the value of copper analysis of young leaf blades for diagnosing copper deficiency in subterranean clover with moderately deficient to luxury supplies of phosphorus.

The uptake and distribution of copper in perennial ryegrass and white clover grown in flowing solution culture with a controlled supply of copper

AbstractThe uptake and distribution of copper was examined in perennial ryegrass and white clover when these were grown in flowing solution culture with a controlled supply of copper at 0.025 mg litre−1 (0.4 μM). Although the concentration of copper in the shoots of white clover was greater than that in those of ryegrass, there was no difference between the two species in (i) absorption per unit of root or (ii) the transport of copper from roots to shoots. Differences in the growth patterns of the two plants may be responsible for differences in copper concentration in their dry matter. The proportion of the shoot's copper that was associated with cell walls fell, during growth over 33 days, from 23 to 12% in ryegrass and from 35 to 7% in white clover. There was some indication that terminating the supply of phosphate to the plants (which did not affect absorption by roots or transport to shoots) may have increased the degree of association of copper with the cell walls of the shoots.

Copper Supply in Relation to Content and Redistribution of Copper Among Organs of the Wheat Plant*

The relationship of copper supply to the content and movement of copper among organs of wheat plants was examined at seven stages in their growth from seedlings to maturity on a copper deficient sand. In the absence of copper (Cu0), plants became severely copper deficient and produced no grain; development of tillers, leaves, stems, and inflorescences was delayed and growth of roots strongly depressed; leaf senescence was retarded and tiller growth was prolonged. Application of a marginal supply of copper (Cu1) overcame all symptoms and promoted growth and grain production. Increasing copper supply eightfold (Cu2) did not change vegetative or grain production. Copper concentrations in stems, individual leaves, and whole tops were highest and responded most strongly to copper supply when they were young. As they aged, Cu1 and Cu2 leaves lost copper rapidly; the first Cu0 leaves retained their copper and remained healthy for more than 7 weeks even though younger leaves developed severe copper deficiency. In all treatments, loss of copper from the oldest leaf paralleled senescence and the loss of nitrogen. It is suggested that copper does not move out of plant leaves until they lose organic nitrogen compounds. As a result, copper behaves in non-senescent leaves as if it is not mobile in plant phloem. But under conditions favouring senescence, copper is highly mobile: in the present experiment, 67 per cent of the copper present in vegetative organs of the Cu2 primary shoot at flowering moved from them during grain development and this could account for all of the copper found in the grain at maturity. The retention of copper by leaves before senescence, its rapid loss during senescence, and the effect of copper deficiency in delaying senescence resulted in the oldest leaf of severely deficient Cu0 plants in the present experiment having a higher copper concentration than that of copper adequate Cu1 and Cu2 plants. This behaviour could account for the many reports of anomalous C-shaped ‘Piper-Steenbjerg’ curves in the relationship of yield to copper concentrations in plant tops. The coupling of copper movement from leaves to nitrogen movement can also account for the unusually high values reported for critical concentrations of copper in tops of plants given high levels of nitrogen fertilizers. Old organs should not be included in samples for diagnosis of copper deficiency. Only young organs should be used. In the present experiment, the copper concentration of young leaves gave a good indication of the copper status of wheat: a value of 1 μg g−1 in young leaves indicated copper deficiency.

Copper Deficiency and Toxicity in Scenedesmus

Summary The microalga Scenedesmus acutus can accumulate high amounts of copper ions. Depending on the concentration in the medium, an enrichment of up to 1000 fold within the cells is possible. For optimum growth a copper supply of 0.1 to 1 µM is necessary. Growth is reduced to 50% of the normal rate and chlorophyll is bleached when the medium is depleted of copper. Copper concentrations exceeding 10 µM are toxic. However, toxicity is temporary only and the algae can adapt to up to 50 µM copper ions within 24 h. During this transient period, chlorophyll is broken down and lipids are decomposed by oxidative processes. By following ethane and ethylene production, lipid peroxidation could be correlated with decrease of photosynthetic oxygen evolution and growth.

Copper, Zinc and Molybdenum in Livers of Norwegian Cattle At Slaughter

The concentrations of copper, zinc and molybdenum were measured in samples of cattle liver from 10 slaughter-houses in Norway. A total of 335 samples were analysed. A clear accumulation of copper with age was found, the average copper level in the younger animals (≦ 3 years, n = 194) being 30 µg Cu/g liver wet weight, and in the older ones (> 3 years, n = 141) 59 µg Gu/g. The range in the copper values found was considerable, though significant differences between some of the districts were recorded. Copper concentrations were classified as low (≦10 µg Gu/g) in 9.6 % of the samples. Zinc showed no accumulation with age, nor were there any differences in zinc levels found in animals from different districts, the average level being 32 µg Zn/g liver wet weight. The picture was the same for molybdenum, no differences between age groups or districts being found. The average level was 1.0 µg Mo/g liver. There was no significant correlation between levels of copper, zinc or molybdenum. The supply of copper and zinc to cattle in Norway seems close to sufficient, but copper- and zinc-fortified mineral supplementation of cattle feed is still to be recommended. There seems to be no need for molybdenum supplementation in cattle.

Disequilibrium Estimation of the Demand for Copper

In this paper we estimate the demand for refined copper in the United States, taking account of the fact that, during much of the sample period, copper supplies were rationed. The model employed here, which is closely related to the Tobit model, is much simpler than those models previously used for disequilibrium estimation. Our empirical results are consistent with institutional evidence on the existence of rationing and suggest that conventional estimates of the demand for copper, which implicitly assume that the market is always in equilibrium, are severely biased.

Absorption, transport and distribution of copper.

This paper deals with the way animals regulate the supply of copper to sites within the body where the metal exercises its functions. Homeostasis is maintained by the control of both absorption and excretion of the metal, although the efficiency with which this balanced is achieved varies between species. These processes are influenced by dietary intake of copper and they also depend on genetic factors, age, dietary composition and the physiological state of the animal. Some of these effects are described, with emphasis on the possible mechanism of absorption of the metal. The distribution of copper after its absorption from the intestine and, in particular, its uptake by the liver and kidneys are also discussed. Much of the copper removed by these organs is incorporated into, and may induce synthesis of, metallothionein. The precise role of this protein in copper metabolism is still, however, a matter of conjecture. The subsequent binding of hepatic copper to metalloenzymes, its excretion in bile and its incorporation into lysosomes during copper overload are also considered.

The distribution of copper and soluble carbohydrates in wheat plants grown at high and low levels of copper supply

AbstractWheat plants were grown at a high and a low level of copper nutrition in deep pots of sandy soil in a glasshouse. Pots were harvested in duplicate every two weeks for five months and plant parts were analysed for soluble carbohydrates and copper.The hypothesis that copper‐deficient plants failed to set grain because concentrations of soluble carbohydrates were too low for grain development could not be sustained by these results, which thereby supported an alternative hypothesis of grain failure owing to pollen sterility. Changes in concentrations of copper and of soluble carbohydrates were not in parallel but often opposing. Retranslocation of copper in relation to changes in relative dry weight of plant parts is discussed.

Long-Acting, More Effective Copper T IUDs: A Summary of U.S. Experience, 1970-75

Use of medication in the form of copper wire coiled around the vertical shaft of an inert plastic carrier was a major innovation in IUD technology. The copper medication enabled the IUD to be small yet as effective as larger nonmedicated devices. Small size permitted the IUDs to be used by women who had never been pregnant. This initial advance was not accompanied by an important improvement in effectiveness. Neither the TCu 200 nor the Copper 7, the first two copper devices, showed substantially lower pregnancy rates in the United States (Tietze and Lewit, 1972; Jain, 1975) or in developing countries (Sivin, 1976). When copper wire devices were introduced, a key question was how long they would remain effective, since their effectiveness stems from the action of copper slowly dissolving in the uterine environment. After prolonged use, some of the copper coils are shed and thereby, in theory, the device becomes less effective. At first, two years of use was thought to be the limit, but as experience accrued the TCu 200 was found to remain effective for three years (Jain and Sivin, 1977), and both the TCu 200 and the Copper 7 have been approved by the US Food and Drug Administration for three full years of use. Data presented in this paper indicate that the TCu 200 provides effective protection against pregnancy for four full years of use. Efforts to increase effectiveness and extend duration of protection have led to the development of two improved Copper T devices. In the TCu 380A, collars or cylinders of copper have been placed on the horizontal arm of the T, each collar providing 30 mm2 of copper surface. These collars fit tightly onto the plastic and can be eroded from one side only. Erosion may pit the surface of the collars but cannot fragment them. Thus the copper in the collars will be available for contraceptive effect for many years. A theoretical advantage of placing collars on the horizontal arms of the T is that the copper supply is brought closer to the fundus of the uterus. Because implantation tends to occur high in the uterus, fundal placement of copper is considered to enhance effectiveness. In addition to the 60 mm2 of copper collars on the horizontal arms, the TCu 380A has 320 mm 2 of thick copper wire on the vertical shaft of the T, a surface area achieved by using more or tighter turns of wire than used in the TCu 200 device. A sixyear lifetime is the minimum duration of effective protection predicted for this device. This prediction is based on the assumption of slow fragmentation of the wire, leaving only the 60 mm2 of copper in the collars available for contraceptive effect after the wire has severely fragmented. In the second new device, the TCu 220C, collars of copper are placed on both the vertical and horizontal arms of the T form. Wire was eliminated entirely. With a total copper surface area of 220 mm2 in the form of collars, an effective lifetime for this device is estimated to be 1015 years, as no fragmentation is to be expected.

The Effect of Copper Supply on the Senescence and the Retranslocation of Nutrients of the Oldest Leaf of Wheat

The contents of Cu, N, P, K, Zn, Mn and Ca were followed during the life of the oldest leaf of wheat plants (Triticum aestivum L. cv. Gamenya) grown at deficient and sufficient supplies of Cu. At both levels of Cu, the Cu content of the oldest leaf behaved in a similar way to the contents of N and Zn, which declined markedly during leaf senescence. By contrast to Cu the P and K contents declined markedly, prior to leaf senescence, whereas the Ca and Mn contents increased throughout the life of the leaf and did not decline during leaf senescence. Interactions among Cu supply, the supply of other nutrients (e.g. N), and leaf senescence account for the variable mobility of Cu in wheat. Similar interactions between nutrient supply and senescence may explain contradictory reports on the redistribution of other nutrients which are variably mobile in plants.

The Effects of Copper Supply and Shading on Retranslocation of Copper from Mature Wheat Leaves

Plants of Gamenya wheat (Triticum aestivum L.) were grown in pots of a Cu-deficient sand at two levels of Cu (deficient and sufficient), and harvested on days 13, 22, 28 and 38. In 50 per cent of the pots in each Cu treatment, the oldest leaf and leaf 2 of the main stem were shaded when they reached full expansion. The Cu content of the oldest leaf of Cu-sufficient, unshaded plants was high at day 13 and declined rapidly to day 38. That of Cu-deficient, unshaded plants was initially relatively low and declined much more slowly, so that at day 38 it resembled that of Cu-sufficient plants. Shading the oldest leaf accelerated the loss of its Cu in both Cu-deficient and Cu-sufficient plants. The effects of shading and of Cu supply on the loss of Cu from the oldest leaf paralleled their effects on the loss of N and chlorophyll. The results suggest that most of the Cu in the oldest leaf does not move out until the leaf senesces. In Cu-deficient plants retention of Cu by old green leaves accentuated Cu deficiency. The release of Cu, resulting from shading the old leaves of Cu-deficient plants, stimulated the growth of new leaves. In Cu-sufficient plants, shading depressed growth.

The effects of copper and nitrogen supply on the distribution of copper in dissected wheat grains

The distribution of copper between the embryo and the endosperm was studied in the grain of two wheat cultivars (Gamenya and Petit Rojo) grown at marginal and sufficient copper and two levels of nitrogen. Copper concentration in whole grain increased markedly with copper level but differed little with nitrogen level. The dry weight and copper content of the embryo expressed as a proportion of the whole grain varied little among treatments, so that copper concentration in the embryo responded to treatment in a similar way to copper concentration in the whole grain. Copper concentrations in the embryo were at least 2.5 times as high as in the endosperm or whole grain at all levels of copper and nitrogen. It is suggested that where copper deficiency decreases grain number without decreasing the weight of individual grains the copper concentration in the mature whole grain, or in the embryo, is not causally related to grain development, and may be a poor indicator of the potential response of grain yield to copper application.