Copper Supply Research Articles

Copper in plants: acquisition, transport and interactions.

Copper is an essential metal for plants. It plays key roles in photosynthetic and respiratory electron transport chains, in ethylene sensing, cell wall metabolism, oxidative stress protection and biogenesis of molybdenum cofactor. Thus, a deficiency in the copper supply can alter essential functions in plant metabolism. However, copper has traditionally been used in agriculture as an antifungal agent, and it is also extensively released into the environment by human activities that often cause environmental pollution. Accordingly, excess copper is present in certain regions and environments, and exposure to such can be potentially toxic to plants, causing phytotoxicity by the formation of reactive oxygen radicals that damage cells, or by the interaction with proteins impairing key cellular processes, inactivating enzymes and disturbing protein structure. Plants have a complex network of metal trafficking pathways in order to appropriately regulate copper homeostasis in response to environmental copper level variations. Such strategies must prevent accumulation of the metal in the freely reactive form (metal detoxification pathways) and ensure proper delivery of this element to target metalloproteins. The mechanisms involved in the acquisition and the distribution of copper have not been clearly defined, although emerging data in last decade, mainly obtained on copper uptake, and both intra- and intercellular distribution, as well as on long-distance transport, are contributing to the understanding of copper homeostasis in plants and the response to copper stress. This review gives an overview of the current understanding of main features concerning copper function, acquisition and trafficking network as well as interactions between copper and other elements.

Mercury and cadmium trigger expression of the copper importer Ctr1B, which enables Drosophila to thrive on heavy metal-loaded food

Organisms from insects to mammals respond to heavy metal load (copper, zinc, cadmium, and mercury) by activating the metal-responsive transcription factor 1 (MTF-1). MTF-1 binds to short DNA sequence motifs, termed metal response elements, and boosts transcription of a number of genes, notably those for metallothioneins. In Drosophila, MTF-1 somewhat counter-intuitively also activates transcription of a copper importer gene (Ctr1B) in response to copper starvation. Here, we report that mutant flies lacking Ctr1B are extremely sensitive to cadmium and mercury treatment, but can be rescued by excess copper in the food. We thus propose that copper, by competing for binding sites on cellular proteins, alleviates the toxic effects of mercury and cadmium. Such a scenario also explains a seemingly fortuitous metal response, namely, that cadmium and mercury strongly induce the expression of a Ctr1B reporter gene. Thus, the transcription enhancer/promoter region of the Ctr1B copper importer gene is subject to three modes of regulation. All of them depend on MTF-1 and all make biological sense, namely, (i) induction by copper starvation, (ii) repression by copper abundance, and (iii), as shown here, induction by cadmium or mercury at normal copper supply.

‘How tyrosinase got its copper’– not a Just So Story!

‘How tyrosinase got its copper’– not a Just So Story!

Liver as a key organ in the supply, storage, and excretion of copper

The liver plays an important role in the disposition of copper. Most dietary copper passes through the liver where it can be used for protein and energy production or excreted through the biliary route. Because copper is a prooxidant, its intracellular handling is tightly managed. In Wilson disease, in which synthesis of ceruloplasmin and biliary excretion of copper are defective, copper accumulates in the liver and leads to progressive liver damage. The features of hepatic Wilson disease are highly variable. The spectrum of liver disease includes mild inflammation, fatty liver, an autoimmune disorder, and cirrhosis. Wilson disease thus resembles drug hepatotoxicity, and indeed it can be regarded as a prototypic example of endogenous hepatotoxicity. Biomarkers developed for detecting drug hepatotoxicity may be relevant to Wilson disease. Biomarkers developed through metalloproteomics, which for copper seeks to define a set of proteins that have copper-binding capacity, or through genomic studies may also be relevant to Wilson disease and other disorders of copper handling, whether copper is deficient or overloaded.

Influence of Additional Micronutrient Supply on Growth, Nutritional Status and Flower Quality of Three Rose Cultivars in a Soilless Culture

ABSTRACT The effect of additional supply of iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) on three rose cultivars was investigated. Five fertilizer treatments were utilized: 0 (control), 150 μ mol Fe L− 1, 150 μ mol Fe + 10 μ mol Mn L− 1, 150 μ mol Fe + 10 μ mol Mn + 12 μ mol Zn L− 1, 150 μ mol Fe + 10 μ mol Mn + 12 μ mol Zn + 5 μ mol Cu L− 1. The results demonstrated significant variation among rose cultivars in developing Zn, Fe, and Mn deficiency symptoms and response to micronutrient supplies. For ‘Modern Girl’ and ‘Orange Juice’, all micronutrient treatments resulted in higher stem length and thickness as compared to the control. No significant increase in stem length was observed in ‘Aqua Fresh’. All cultivars had the greatest flower vase life in the added Zn treatments. All fertilizer treatments significantly increased Fe concentration in the leaves of ‘Modern Girl’ and ‘Aqua Fresh’ as compared to the control. The Fe-Mn-Zn-Cu treatment significantly increased leaf concentration of Mn, Zn, and Cu in all cultivars. Leaf sodium (Na) concentration was lower in the micronutrient treatments that included Zn addition as compared to the treatments that did not include added Zn. No visible mildew symptom was observed in the treatments with Zn addition. The results showed that genotypic variation and sufficient micronutrient supply are two key factors in success production of rose in the soilless culture. Furthermore, the results indicated the importance of Zn in enhancing the quality of the rose flower.

Einfluss unterschiedlicher Kupfer und Zinkversorgung auf deren Konzentrationen in Blutserum, Leber und Deckhaar bei Milchkühen

In a feeding trial at the Institute of Animal Nutrition of the Federal Research Institute of Animal Health (FLI) over 12 weeks with 20 cows of the German Holstein Breed the influence of different copper and zinc contents in the ration on their concentration in blood serum, liver and hair was tested. All animals received a diet based on maize- and grass silage ad libitum. The animals were divided in two groups with 10 cows each; group A received a concentrate according to their milk yield with a copper and zinc content as recommended (GfE 2001), whereas group B was offered a concentrate with roughly the double amount of copper and zinc. At the beginning and at the end of the trial a sample of blood, pigmented hair and a liver bioptate was taken from all animals to evaluate the incorporation of copper and zinc in these tissues. In serum and pigmented hair the copper concentrations did not differ between the two groups [13.4 for Group A and 12.5 micromol/L for Group B in serum respectively 6.8 (Group A) and 7.4 mg/kg DM (Group B) in pigmented hair]. Only the copper concentration in the liver was influenced by the different feeding. The higher copper content for group B resulted in a significantly higher copper concentration in the liver (506 mg/kg DM compared to 383 mg/kg DM). The liver is the best indicator organ for a sufficient copper supply. An increase in the zinc content in the ration resulted neither in higher zinc concentrations in serum (15.1 in Group B in comparison to 13.4 micromol/L for Group A) nor in higher zinc concentrations in liver (140 for Group B and 112 mg/kg DM for Group A) and pigmented hair (130 in Group A and 123 mg/kg DM in Group B). There is a significant correlation between copper intake and copper concentration in the liver (r = 0.46), whereas the correlation between zinc intake and zinc concentration in the liver is only tendencially (r = 0.23). The three tested samples serum, liver and cow hair are not qualified to reflect exactly a sufficient zinc supply.

MicroRNA-mediated Systemic Down-regulation of Copper Protein Expression in Response to Low Copper Availability in Arabidopsis

In plants, copper is an essential micronutrient required for photosynthesis. Two of the most abundant copper proteins, plastocyanin and copper/zinc superoxide dismutase, are found in chloroplasts. Whereas plastocyanin is essential for photo-autotrophic growth, copper/zinc superoxide dismutase is dispensable and in plastids can be replaced by an iron superoxide dismutase when copper is limiting. The down-regulation of copper/zinc superoxide dismutase expression in response to low copper involves a microRNA, miR398. Interestingly, in Arabidopsis and other plants, three additional microRNA families, miR397, miR408, and miR857, are predicted to target the transcripts for the copper protein plantacyanin and members of the laccase copper protein family. We confirmed the predicted targets of miR397, miR408, and miR857 experimentally by cleavage site analysis. To study the spatial expression pattern of these microRNAs and the effect of copper on their expression, we analyzed Arabidopsis grown hydroponically on different copper regimes. On low amounts of copper the plants accumulated miR397, miR408, and miR857. The microRNA expression pattern was negatively correlated with the accumulation of transcripts for plantacyanin and laccases. Furthermore, the expression of other laccases that are not predicted targets for known microRNAs was similarly regulated in response to copper. For some of these laccases, the regulation was disrupted in a microRNA maturation mutant (hen1-1), suggesting the presence of other copper-regulated microRNAs. Thus, in Arabidopsis, microRNA-mediated down-regulation is a general mechanism to regulate nonessential copper proteins. We propose that this mechanism allows plants to save copper for the most essential functions during limited copper supply.

Effects of parenteral supply of iron and copper on hematology, weight gain, and health in neonatal dairy calves

The objective of the present study was to examine the effects of parenteral administration of iron and copper on hematological parameters, weight gain, and health of neonatal dairy calves in the period when iron and copper deficiency could be existed. Twenty-four Holstein calves were used for the experiment and randomly assigned to four different treatments. Treatments consisted of (1) control (no injections of Fe and Cu), (2) test 1 (1000 mg Fe as fe-dextran was injected to each calf at day 2 of age), (3) test 2 (160 mg Cu as methionine-copper complex was injected to each calf at day 14 of age), and (4) test 3 (Fe and Cu were injected to each calf as mentioned previously). Blood samples were collected from all of the calves within 24-48 hours after birth and at 7, 14, 21 and 28 days of age for measuring hematological parameters and within 24-48 hours after birth and at 14, 21 and 28 days of age for the determination of iron, copper, TIBC concentrations, and AST activity. Anti-coagulated blood was analyzed shortly after collection for: number of red blood cell (RBC), hemoglobin (Hb), heamatocrit (HCT), total leukocyte count (WBC), Platelet (Plt), MCH, MCV, MCHC, and differential leukocyte counts. The amounts of iron, copper, TIBC, and AST were measured in serum. Group had significant effects on the amounts of HCT, RBC, hemoglobin, MCV, neutrophil, weekly weight gain, and daily gain during each week (p < 0.05). Sampling time had significant effects on the amounts of RBC, MCV, MCH, MCHC, WBC, neutrophil, lymphocyte, monocyte, platelet, fibrinogen, copper, TIBC, AST, weight, weekly gain and, daily gain during each week (p < 0.05). significant interactions between sampling time and group were seen for HCT, RBC, hemoglobin, MCV, platelet, total protein, fibrinogen, iron, and TIBC (p < 0.05). Improved RBC parameters and MCV were seen in calves of group 4 (test 3) in comparing with control group. Total and daily gains were also significantly improved in test groups in comparing with control group (p < 0.05). No significant difference was seen for the days of treatment between groups.

Functional Characterization of CgCTR2, a Putative Vacuole Copper Transporter That Is Involved in Germination and Pathogenicity inColletotrichum gloeosporioides

Copper is a cofactor and transition metal involved in redox reactions that are essential in all eukaryotes. Here, we report that a vacuolar copper transporter that is highly expressed in resting spores is involved in germination and pathogenicity in the plant pathogen Colletotrichum gloeosporioides. A screen of C. gloeosporioides transformants obtained by means of a promoterless green fluorescent protein (GFP) construct led to the identification of transformant N159 in which GFP signal was observed in spores. The transforming vector was inserted 70 bp upstream of a putative gene with homology to the Saccharomyces cerevisiae vacuolar copper transporter gene CTR2. The C. gloeosporioides CTR2 (CgCTR2) gene fully complemented growth defects of yeast ctr2Delta mutants, and a CgCTR2-cyan fluorescent protein (CFP) fusion protein accumulated in vacuole membranes, confirming the function of the protein as a vacuolar copper transporter. Expression analysis indicated that CgCTR2 transcript is abundant in resting conidia and during germination in rich medium and downregulated during "pathogenic" germination and the early stages of plant infection. CgCTR2 overexpression and silencing mutants were generated and characterized. The Cgctr2 mutants had markedly reduced Cu superoxide dismutase (SOD) activity, suggesting that CgCTR2 is important in providing copper to copper-dependent cytosolic activities. The Cgctr2-silenced mutants had increased sensitivity to H2O2 and reduced germination rates. The mutants were also less virulent to plants, but they did not display any defects in appressorium formation and penetration efficiency. An external copper supply compensated for the hypersensitivity to H2O2 but not for the germination and pathogenicity defects of the mutants. Similarly, overexpression of CgCTR2 enhanced resistance to H2O2 but had no effect on germination or pathogenicity. Our results show that copper is necessary for optimal germination and pathogenicity and that CgCTR2 is involved in regulating cellular copper balance during these processes.

An Oxidized Tryptophan Facilitates Copper Binding in Methylococcus capsulatus-secreted Protein MopE

Proteins can coordinate metal ions with endogenous nitrogen and oxygen ligands through backbone amino and carbonyl groups, but the amino acid side chains coordinating metals do not include tryptophan. Here we show for the first time the involvement of the tryptophan metabolite kynurenine in a protein metal-binding site. The crystal structure to 1.35 angstroms of MopE* from the methane-oxidizing Methylococcus capsulatus (Bath) provided detailed information about its structure and mononuclear copper-binding site. MopE* contains a novel protein fold of which only one-third of the structure displays similarities to other known folds. The geometry around the copper ion is distorted tetrahedral with one oxygen ligand from a water molecule, two histidine imidazoles (His-132 and His-203), and at the fourth distorted tetrahedral position, the N1 atom of the kynurenine, an oxidation product of Trp-130. Trp-130 was not oxidized to kynurenine in MopE* heterologously expressed in Escherichia coli, nor did this protein bind copper. Our findings indicate that the modification of tryptophan to kynurenine and its involvement in copper binding is an innate property of M. capsulatus MopE*.

Revisiting the Cumulative Grade-Tonnage Relationship for Major Copper Ore Types

In order to develop long-term scenarios of copper supply and demand, a grade-tonnage density function model was developed for four major copper ore types. The model was used to create cumulative grade-tonnage curves, representing 1,778 million metric tons (Mt) of mineable copper. These cumulative curves were then validated against 70 years of historical world average ore grade using production input by ore type from 1800 to 2000. Additionally, the curves were used in conjunction with estimates of the ultimate porphyry resource and copper concentration in common rocks to conduct a rough analysis of the validity of the bimodal log-Gaussian distribution hypothesis for the global copper resource base. The resulting analysis did not confirm or refute the hypothesis but did provide guidance as to the way in which data from new resource exploration can be used to address the issue of the ultimate mineable copper resource. As ore deposit grade-tonnage data for other geochemically scarce metals becomes available, the methods described in this paper can serve as a template for further investigations of resource quality.

Copper transport and Alzheimer’s disease

This brief review discusses copper transport in humans, with an emphasis on knowledge learned from one of the simplest model organisms, yeast. There is a further focus on copper transport in Alzheimer's Disease (AD). Copper homeostasis is essential for the well-being of all organisms, from bacteria to yeast to humans: survival depends on maintaining the required supply of copper for the many enzymes, dependent on copper for activity, while ensuring that there is no excess free copper, which would cause toxicity. A virtual orchestra of proteins are required to achieve copper homeostasis. For copper uptake, Cu(II) is first reduced to Cu(I) via a membrane-bound reductase. The reduced copper can then be internalised by a copper transporter where it is transferred to copper chaperones for transport and specific delivery to various organelles. Of significance are internal copper transporters, ATP7A and ATP7B, notable for their role in disorders of copper deficiency and toxicity, Menkes and Wilson's disease, respectively. Metallothioneins and Cu/Zn superoxide dismutase can protect against excess copper in cells. It is clear too, increasing age, environmental and lifestyle factors impact on brain copper. Studies on AD suggest an important role for copper in the brain, with some AD therapies focusing on mobilising copper in AD brains. The transport of copper into the brain is complex and involves numerous players, including amyloid precursor protein, A beta peptide and cholesterol.

Geochemical constraints on sustainable development: Can an advanced global economy achieve long-term stability?

The eighty-one stable chemical elements are examined individually with respect to (i) recent annual demand and (ii) worst case long-term availability in a distant future in which they must be extracted from the background sources of air, seawater, and ordinary rock. It is shown that, if a conventional use scenario is envisioned, the supplies of ruthenium, rhodium, palladium, tellurium, rhenium, osmium, iridium, platinum, gold, and especially phosphorus will be questionable while the supplies of copper, zinc, molybdenum, silver, cadmium, tin, antimony, tungsten, mercury, lead, and bismuth will be inadequate. It is therefore concluded that, in the long run, only the promotion of massive recycling and substitution technologies will suffice to maintain the global industrial society now developing.

A Structural Characterization of Human SCO2

Human Sco2 is a mitochondrial membrane-bound protein involved in copper supply for the assembly of cytochrome c oxidase in eukaryotes. Its precise action is not yet understood. We report here a structural and dynamic characterization by NMR of the apo and copper(I) forms of the soluble fragment. The structural and metal binding features of human Cu(I)Sco2 are similar to the more often studied Sco1 homolog, although the dynamic properties and the conformational disorder are quite different when the apo forms and the copper(I)-loaded forms of the two proteins are compared separately. Such differences are accounted for in terms of the different physicochemical properties in strategic protein locations. The misfunction of the known pathogenic mutations is discussed on the basis of the obtained structure.

Trafficking of a Secretory Granule Membrane Protein Is Sensitive to Copper

We explored the effect of copper availability on the synthesis and trafficking of peptidylglycine alpha-amidating monooxygenase (PAM), an essential cuproenzyme whose catalytic domains function in the lumen of peptide-containing secretory granules. Corticotrope tumor cell lines expressing integral membrane and soluble forms of PAM were depleted of copper using bathocuproinedisulfonic acid or loaded with copper by incubation with CuCl(2). Depleting cellular copper stimulates basal secretion of soluble enzyme produced by endoproteolytic cleavage of PAM in secretory granules and transit of membrane PAM though the endocytic pathway and back into secretory granules. Unlike many cuproenzymes, lack of copper does not lead to instability of PAM. Copper loading decreases cleavage of PAM in secretory granules, secretion of soluble enzyme, and the return of internalized PAM to secretory granules. The trafficking and stability of the soluble, luminal domain of PAM and truncated membrane PAM lacking a cytosolic domain are not affected by copper availability. Taken together, our data demonstrate a role for copper-sensitive cytosolic machinery in directing endocytosed membrane PAM back to secretory granules or to a degradative pathway. The response of PAM to lack of copper suggests that it facilitates copper homeostasis.

A Periplasmic Iron-binding Protein Contributes toward Inward Copper Supply

Periplasmic substrate binding proteins are known for iron, zinc, manganese, nickel, and molybdenum but not copper. Synechocystis PCC 6803 requires copper for thylakoid-localized plastocyanin and cytochrome oxidase. Here we show that mutants deficient in a periplasmic substrate binding protein FutA2 have low cytochrome oxidase activity and produce cytochrome c6 when grown under copper conditions (150 nm) in which wild-type cells use plastocyanin rather than cytochrome c6. Anaerobic separation of extracts by two-dimensional native liquid chromatography followed by metal analysis and peptide mass-fingerprinting establish that accumulation of copper-plastocyanin is impaired, but iron-ferredoxin is unaffected in DeltafutA2 grown in 150 nm copper. However, recombinant FutA2 binds iron in preference to copper in vitro with an apparent Fe(III) affinity similar to that of its paralog FutA1, the principal substrate binding protein for iron import. FutA2 is also associated with iron and not copper in periplasm extracts, and this Fe(III)-protein complex is absent in DeltafutA2. There are differences in the soluble protein and small-molecule complexes of copper and iron, and the total amount of both elements increases in periplasm extracts of DeltafutA2 relative to wild type. Changes in periplasm protein and small-molecule complexes for other metals are also observed in DeltafutA2. It is proposed that FutA2 contributes to metal partitioning in the periplasm by sequestering Fe(III), which limits aberrant Fe(III) associations with vital binding sites for other metals, including copper.

Human Sco1 functional studies and pathological implications of the P174L mutant

The pathogenic mutant (P174L) of human Sco1 produces respiratory chain deficiency associated with cytochrome c oxidase (CcO) assembly defects. The solution structure of the mutant in its Cu(I) form shows that Leu-174 prevents the formation of a well packed hydrophobic region around the metal-binding site and causes a reduction of the affinity of copper(I) for the protein. K(D) values for Cu(I)WT-HSco1 and Cu(I)P174L-HSco1 are approximately 10(-17) and approximately 10(-13), respectively. The reduction potentials of the two apo proteins are similar, but slower reduction/oxidation rates are found for the mutant with respect to the WT. The mitochondrial metallochaperone in the partially oxidized Cu(1)(I)Cox17(2S-S) form, at variance with the fully reduced Cu(4)(I)Cox17, interacts transiently with both WT-HSco1 and the mutant, forming the Cox17/Cu(I)/HSco1 complex, but copper is efficiently transferred only in the case of WT protein. Cu(1)(I)Cox17(2S-S) indeed has an affinity for copper(I) (K(D) approximately 10(-15)) higher than that of the P174L-HSco1 mutant but lower than that of WT-HSco1. We propose that HSco1 mutation, altering the structure around the metal-binding site, affects both copper(I) binding and redox properties of the protein, thus impairing the efficiency of copper transfer to CcO. The pathogenic mutation therefore could (i) lessen the Sco1 affinity for copper(I) and hence copper supply for CcO or (ii) decrease the efficiency of reduction of CcO thiols involved in copper binding, or both effects could be produced by the mutation.

Distinct Functional Roles for the Menkes and Wilson Copper Translocating P-type ATPases in Human Placental Cells

Background/Aims: The copper transporting ATPases, Menkes (ATP7A; MNK) and Wilson (ATP7B; WND) are essential for normal copper transport in the human body. The placenta is the key organ in copper supply to the fetus during pregnancy and it is one of the few organs in the body to express both of the ATPases. The placenta therefore provides a unique opportunity to elucidate the specific roles of these transporters within the one cell type. Methods/Results: Using polarized placental Jeg-3 cells, siRNA technology and radio-labelled ⁶⁴Cu transport assays, MNK and WND were shown to have distinct roles in the vectorial transport of copper. MNK transported copper from the cell via the basolateral membrane and in contrast, WND transported copper from the apical membrane. Inactivation of MNK resulted in decreased activity of two important cuproenzymes, lysyl oxidase and Cu/Zn-superoxide dismutase. Conclusions: Overall, these results provide definitive evidence for distinct roles of MNK and WND in the human placenta, and are consistent with a role for MNK in the transport of copper into the fetal circulation, and through delivery of copper to placental cuproenzymes, whilst WND contributes to the maintenance of placental copper homeostasis by transporting copper to the maternal circulation.

Wilson disease: not just a copper disorder. Analysis of a Wilson disease model demonstrates the link between copper and lipid metabolism

Copper is an essential nutrient required for normal growth and development in many organisms. In humans, the disruption of normal copper absorption and excretion is associated with two severe disorders, known as Menkes disease and Wilson disease, respectively. The consequences of insufficient copper supply that is characteristic of Menkes disease have been largely linked to the inactivation of key metabolic enzymes, although other non-enzymatic processes may also be involved. In contrast, the consequences of copper accumulation in Wilson disease have been generally ascribed to copper-induced radical-mediated damage. Recent studies suggest that the cellular response to copper overload, particularly at the early stages of copper accumulation, involves more specific mechanisms and specific pathways. Genetic and metabolic characterization of animal models of Wilson disease has provided new insights into the pre-symptomatic effects of copper that is accumulated in the liver. The studies have uncovered unexpected links between copper metabolism, cell-cycle machinery, and cholesterol biosynthesis. We discuss these new findings along with the earlier reports on dietary effects of copper. Together these experiments suggest a tight link between lipid and copper metabolism and identify several candidate proteins that may mediate the cross-talk between copper status and lipid metabolism.

Assessment of zinc and copper status in weaned piglets in relation to dietary zinc and copper supply

The aim of the study was to determine the effect of weaning and the effect of increasing dietary zinc concentrations on the zinc and copper status of weaned piglets (study 1) and to study the effect of high concentrations of dietary zinc and/or copper on zinc and copper status of weaned piglets (study 2). Study 1 included 54 piglets (six litters of nine piglets). One piglet from every litter was killed 1 day before weaning. The remaining 48 piglets were allocated at weaning (28 days) to four dietary zinc treatments (100, 250, 1000 or 2500 ppm) and subsequently killed 1-2, 5-6 or 14-15 days after weaning. Study 2 included 48 piglets (six litters of eight piglets) allocated to four dietary treatments, consisting of low or high dietary zinc (100 or 2500 ppm) in combination with low or high dietary copper (20 or 175 ppm). All piglets in study 2 were killed 5-7 days after weaning. In both studies, the trace mineral status was assessed by zinc and copper concentrations and alkaline phosphatase (AP) activity in plasma and mucosal tissue. In study 2, lymphocyte metallothionein (MT) mRNA and intestinal mucosa MT mRNA concentrations were included as zinc status markers. The results showed that the zinc status, measured as zinc in plasma and mucosa, was not affected by weaning of the piglets. Plasma copper concentrations decreased during the first 2 weeks after weaning. High dietary copper concentrations did not affect the concentration of copper in plasma, but increased the concentration of copper in mucosa and the concentration of zinc in plasma. The dietary zinc treatments increased the zinc concentration in plasma as well as the zinc and MT mRNA concentration in mucosa. Lymphocyte MT mRNA concentrations did not reflect the differences in dietary zinc supplementation.