Failure to confirm abnormal copper utilization in crinkler (cr) mice

A number of aspects of copper utilization have been studied in crinkled mice, the symptoms of which have been claimed to result from copper deficiency. In none of these aspects has any evidence been found to support this contention.1. Copper concentrations in liver, kidney, and brain, and serum ceruloplasmin oxidase activity were normal incr/cr mice.2. Copper concentrations in cultured lung fibroblasts and kidney epithelial cells derived fromcr/cr mice were normal.3. The elution profile of bound copper by gel-filtration chromatography of liver homogenates was the same in +/? andcr/cr mice.4. Neither maternal nor direct copper supplementation resulted in any reduction in mortality ofcr/cr mice.5. No increase in the concentration of hair sulfhydryl groups was apparent incr/cr mice.6. Histological studies revealed that the thin skin incr/cr mice owed to a reduction of the cutis; the epidermal and dermal layers were of normal thickness.7. Lysyl oxidase activity was normal in extracts of skin from 6-day-oldcr/cr mice, and in the culture medium ofcr/cr lung fibroblasts.8. Chemical analysis of brain myelin from 21- and 60-day-oldcr/cr mice showed no differences from +/? mice.     

Chronological changes in tissue copper, zinc and iron in the toxic milk mouse and effects of copper loading

The toxic milk (tx) mouse is a rodent model for Wilson disease, an inherited disorder of copper overload. Here we assessed the effect of copper accumulation in the tx mouse on zinc and iron metabolism. Copper, zinc and iron concentrations were determined in the liver, kidney, spleen and brain of control and copper-loaded animals by atomic absorption spectroscopy. Copper concentration increased dramatically in the liver, and was also significantly higher in the spleen, kidney and brain of control tx mice in the first few months of life compared with normal DL mice. Hepatic zinc was increased with age in the tx mouse, but zinc concentrations in the other organs were normal. Liver and kidney iron concentrations were significantly lower at birth in tx mice, but increased quickly to be comparable with control mice by 2 months of age. Iron concentration in the spleen was significantly higher in tx mice, but was lower in 5 day old tx pups. Copper-loading studies showed that normal DL mice ingesting 300 mg/l copper in their diet for 3 months maintained normal liver, kidney and brain copper, zinc and iron levels. Copper-loading of tx mice did not increase the already high liver copper concentrations, but spleen and brain copper concentrations were increased. Despite a significant elevation of copper in the brain of the copper-loaded tx mice no behavioural changes were observed. The livers of copper-loaded tx mice had a lower zinc concentration than control tx mice, whilst the kidney had double the concentration of iron suggesting that there was increased erythrocyte hemolysis in the copper-loaded mutants.     

Cadmium, copper and zinc in tissues of deceased copper smelter workers

Workers at a copper and lead smelter in northern Sweden have a multifactorial exposure to a number of heavy metals. The concentrations of cadmium, copper and zinc in liver, lung, kidney and brain tissues have been determined by atomic absorption spectrometry in 32 deceased long-term exposed male lead smelter workers, and compared with those of 10 male controls. Furthermore, copper and zinc levels in hair and nails were determined by energy-dispersive X-ray fluorescence.

The highest cadmium concentrations among both workers and controls were observed in kidney, followed in order by liver, lung and brain. The levels in kidney, liver and lung were all significantly higher in the workers than in the controls (p < 0.03). Among the workers relatively strong positive correlations (p < 0.03) were observed between cadmium concentrations in liver and lung, liver and kidney, liver and brain, and lung and brain. In the exposed workers a positive correlation was observed between cadmium and zinc concentrations in the kidney (r_s = 0.38; p = 0.034). This is probably mainly due to the protein metallothionein, which is stored in the kidney, binding equimolar amounts of these two metals.

The highest concentrations of copper were found in hair and nails among both workers and controls, followed in order by liver, brain, kidney and lung. The tissue concentrations of copper in brain, lung and kidney were all significantly higher among the smelter workers than in the controls (p ≤ 0.036). Copper levels in lung and age at time of death were positively correlated among the exposed workers (r_s = 0.39; p = 0.029). In the same group, positive correlations between copper and zinc concentrations in kidney (r_s = 0.45; p = 0.009) and nails (r_s = 0.68; p < 0.001) were also observed, reflecting possible biological interactions between these two metals.

Among both workers and controls, the highest zinc concentrations were found in hair, followed in order by nails, liver, kidney, brain and lung. Significantly higher tissue concentrations among the workers as compared with the reference group were noted in kidney, liver and brain (p ≤ 0.033).

Neither copper nor zinc concentrations in hair and nails seemed to provide a useful measure of the trace element status of the smelter workers.     

Serum and liver zinc,copper, and iron in chicks infected withEimeria acervulina orEimeria tenella

Two-wk-old broiler chicks were inoculated via crop intubation withEimeria acervulina at two doses: 10⁵ or 10⁶ sporulated oocysts/bird or withEimeria tenella at a dose of 10⁵ sporulated oocysts/bird. Serum and liver samples were collected on days 3 and 6 post-inoculation (PI). There were no significant changes in serum or liver zinc, copper, and iron concentrations in any of the infected groups by 3 d PI. However, on d 6, PI serum protein was significantly reduced in all of the infected groups compared to their pair-fed controls. The chicks infected withE. tennella had significantly reduced serum zinc (1.20 vs 1.77 μg/mL) and iron (0.44 vs 1.28 μg/mL) concentrations and significantly elevated serum copper (0.28 vs 0.17 μg/mL) and ceruloplasmin levels (20.33 vs 11.11 μg/mL) compared to their pair-fed counterparts. Those chicks infected withE. acervulina (10⁶ oocysts/bird) exhibited significantly reduced serum iron concentration by 6 days PI (0.90 vs 1.14 μg/mL). Liver zinc was significantly increased in the chicks infected withE. tenella (349 vs 113 μg/g dry liver wt), as was copper (24 vs 19 μg/g), whereas liver iron concentration was significantly reduced (172 vs 243 μg/g) compared to pair-fed controls. At both dose levels, the chicks infected withE. acervulina exhibited a significant reduction in liver iron by 6 d PI. Hepatic cytosol metals generally reflected whole tissue levels. Metallothionein (MT)-bound zinc was significantly elevated in the chicks infected withE. tenella. Iron bound to a high molecular weight, heat-stable protein fraction (presumably cytoplasmic ferritin) was significantly reduced in chicks infected withE. acervulina, as well as those infected withE. tenella. Collectively, the changes in serum zinc, copper, and iron concentrations, as well as the changes in hepatic zinc and MT-zinc concentrations in the chicks infected withE. tenella were similar to changes evoked during an acute phase response to infection. It is possible that a secondary bacterial infection or inflammation stemming from erosion of the lining of the cecum may play a role in the response of trace element metabolism to theE. tenella infection. Mentions of a trademarkr, proprietary product or specific equipment does not consitute a guarantee or warranty by the US Department of Agriculture and does not imply its approval to the exclusion of other products.     

Effect of dietary copper and zinc levels on tissue copper,zinc, and iron in male rats

The interaction between dietary copper and zinc as determined by tissue concentrations of trace elements was investigated in male Sprague-Dawley rats. Animals were fed diets in a factorial design with two levels of copper (0.5, 5 μg/g) and five levels of zinc (1, 4.5, 10, 100, 1000 μg/g) for 42 d. In rats fed the low copper diet, as dietary zinc concentration increased, the level of copper decreased in brain, testis, spleen, heart, liver, and intestine. There was no significant effect of dietary copper on tissue zinc levels. In the zinc-deficient groups, the level of iron was higher in most tissues than in tissues from controls (5 μg Cu, 100 μg Zn/g diet). In the copper-deficient groups, iron concentration was higher than control values only in the liver. These data show that dietary zinc affected tissue copper levels primarily when dietary copper was deficient, that dietary copper had no effect on tissue zinc, and that both zinc deficiency and copper deficiency affected tissue iron levels.     

Amelioration by copper supplementation of mutant gene effects in the crinkled mouse.

The possibility of a relationship between the autosomal recessive mutant gene crinkled in mice and copper metabolism was investigated by examining the effect of copper supplementation during pregnancy and lactation on the expression of the gene in homozygous mutant young. Survival of mutant mice to 30 days of age was doubled by feeding their mothers a high copper diet (500 ppm copper) during pregnancy and lactation, as compared with controls (6-11 ppm dietary copper). High dietary copper also prevented the lag in pigment development characteristic of the mutants. Furthermore, skin and epidermal thickness and hair bulb development were nearly normal in the high copper group, in contrast to thin skin and paucity of hairs in controls. Supplementation with manganese did not have these effects. Scanning electron micrographs showed the presence of three types of hair abnormalities in crinkled mutants, monilethrix, pili torti, and possibly trichorrhexis nodosa. The results show that increased availability of copper favorably altered the expression of the mutant gene, and demonstrate the interaction of a gene and a trace metal in development.     

Developmental variation in copper,zinc and metallothionein mRNA in brindled mutant and nutritionally copper deficient mice

The concentrations of copper, zinc and metallothionein-I (MT-I) mRNA were determined in the liver, kidney and brain of the brindled mutant mouse from birth until the time of death. Despite accumulation of copper in the kidney of the mutant, MT-I mRNA concentrations were normal. There was no difference between the MT-I mRNA in the brain of mutant and normal in the first 10 days of life, but after day 10 metallothionein mRNA levels were increased in the mutant. The concentration of copper was very low in the liver of the mutant, and on day 6 after birth the metallothionein mRNA was also reduced by about 50%. This reduction was not seen in copper-deficient 6-day-old pups, despite very low hepatic copper levels. This suggests that the lower hepatic MT-I mRNA in the day 6 brindled mouse was not simply due to the reduction in hepatic copper and also that hepatic copper is not regulating metallothionein gene expression the liver of neonatal mice. After day 12 hepatic MT-I mRNA levels were elevated in mutant and in copper deficient mice, both of which die at 14 to 16 days. These increases and the increase in brain MT-I mRNA in older mutant mice are likely to be caused by stress. Overall the results support the conclusions that the brindled mutation does not cause a constitutive activation of the metallothionein genes, and that the differences in metallothionein mRNA between mutant and normal are most probably secondary consequences of the mutation.     

Developmental variation in copper, zinc and metallothionein mRNA in brindled mutant and nutritionally copper deficient mice.

The concentrations of copper, zinc and metallothionein-I (MT-I) mRNA were determined in the liver, kidney and brain of the brindled mutant mouse from birth until the time of death. Despite accumulation of copper in the kidney of the mutant, MT-I mRNA concentrations were normal. There was no difference between the MT-I mRNA in the brain of mutant and normal in the first 10 days of life, but after day 10 metallothionein mRNA levels were increased in the mutant. The concentration of copper was very low in the liver of the mutant, and on day 6 after birth the metallothionein mRNA was also reduced by about 50%. This reduction was not seen in copper-deficient 6-day-old pups, despite very low hepatic copper levels. This suggests that the lower hepatic MT-I mRNA in the day 6 brindled mouse was not simply due to the reduction in hepatic copper and also that hepatic copper is not regulating metallothionein gene expression the liver of neonatal mice. After day 12 hepatic MT-I mRNA levels were elevated in mutant and in copper deficient mice, both of which die at 14 to 16 days. These increases and the increase in brain MT-I mRNA in older mutant mice are likely to be caused by stress. Overall the results support the conclusions that the brindled mutation does not cause a constitutive activation of the metallothionein genes, and that the differences in metallothionein mRNA between mutant and normal are most probably secondary consequences of the mutation.     

Zinc,Copper, Iron,and Selenium Levels in Brain and Liver of Mice Exposed to Acrylonitrile

The mechanism of toxicity of acrylonitrile (AN) has not been fully defined. The research described herein was undertaken to investigate the possible effects of AN on the levels of metallic elements in liver and brain of mice. Thirty-two mice were randomly assigned to four separate groups and treated intraperitoneal (i.p.) once daily for 1 week. Mice in the control group received normal saline, and mice in the three exposure groups received 5, 10, or 20 mg AN/kg b.w. Samples of brain and liver were collected immediately after decapitation. Tissue levels of trace elements (zinc, copper, iron) were determined with flame atomic absorption spectrophotometer or double channel atomic fluorescence absorption spectrophotometer (selenium). Mean brain weights of AN-treated mice were increased as a function of dose compared to controls, but there was no significant change in the ratio of liver/body weight in the four groups. While mean brain zinc decreased as a function of AN dosage, mean liver zinc of the low-dose group significantly increased (p < 0.05); mean liver copper in the medium-dose AN group was significantly higher compared to controls (p < 0.05); however, mean brain copper was increased, but the difference did not attain statistical significance in the three AN groups when compared with the controls (p > 0.05). Mean brain iron levels were significantly decreased in the middle-dose AN group (p < 0.05), but there were no consistent changes in liver iron. Tissue levels of selenium in brain and liver were similar for the control and AN treatment groups. AN induces significant and differential changes in the levels of zinc, copper, and iron in brain and liver. These changes likely play a pivotal role in mediating AN toxicity, most likely via changes in cellular redox status.     

A study of dose response and organ susceptibility of copper toxicity in a rat model

Copper (Cu) in higher concentration is toxic and results in various organ dysfunction. We report Cu concentration in liver, brain and kidney in the rat model following chronic exposure of oral copper sulphate at different subtoxic doses and correlate the tissue Cu concentrations with respective organ dysfunction. Fifty-four male wistar rats divided in 3 groups, the control group received saline water and the experimental group (Group-IIA and IIB) received oral copper sulphate in dose of 100 and 200 mg/kg Body Weight. At the end of 30 days, 60 days and 90 days of exposure, six rats were sacrificed from each group. The maximum peak force in grip strength, latency to fall in rotarod and percentage attention score in Y-maze were significantly reduced in the copper sulphate exposed rats compared to the controls at all time points and these were more marked in Group-IIB compared to Group-IIA. Cu concentration was significantly higher in liver, kidney and brain in the Group-II compared to the Group-I. The Cu concentration was highest in the liver (29 folds) followed by kidney (3 folds) and brain (1.5 folds). Serum ALT, AST and bilirubin correlated with liver Cu, BUN with kidney Cu, and grip strength, rotarod and Y-maze findings correlated with brain Cu level. In rats, chronic oral copper sulphate exposure at subtoxic level results in neurobehavioral abnormality and liver and kidney dysfunctions due to increased Cu concentration in the respective organs. Liver is the most vulnerable organ and copper toxicity increases with increasing dose and duration of exposure.     

Developmental changes in hepatic metallothionein, zinc, and copper levels in genetically altered mice.

Using mice that either overexpress metallothionein 1 (MT-1*) or do not express metallothionein 1 and 2 (MT-null) and a control strain (C57BL/6), the essential metal storage function of hepatic metallothionein and its subcellular localization were investigated during development. Hepatic metallothionein, zinc, and copper levels were measured in all groups from gestational day 20 to 60 days of age. Hepatic metallothionein levels were maximal during the perinatal period in both MT-1* and C57BL/6 mice with levels approximately three times higher in MT-1* mice. MT-null mice had no detectable hepatic metallothionein throughout development. Hepatic zinc levels were highest in the neonatal period of MT-1* and C57BL/6 mice and declined to adult levels by 30 days of age, while hepatic zinc levels in MT-null mice did not vary markedly throughout development. Hepatic copper profiles were very similar in MT-1* and MT-null mice as compared with the C57BL/6 mice. Correlation analysis showed a strong positive correlation between hepatic metallothionein and zinc levels in MT-1* mice, moderate correlation between hepatic metallothionein and metals in C57BL/6 mice, but only a very weak correlation between hepatic metallothionein and copper levels in MT-1* mice. Immunohistochemical localization showed specific nuclear staining in both MT-1* and C57BL/6 mice during the neonatal period with a gradual shift to the cytoplasm. The results show that hepatic metallothionein is a major determinant of zinc but not copper levels during murine development. Additionally, hepatic metallothionein levels and localization are regulated in a similar manner in MT-1* and C57BL/6 mice. The MT-null mice maintain a basel level of zinc sufficient for development, which was found to be 15.9 micrograms/g. This value was similar to the levels of hepatic zinc that was not bound to metallothionein in MT-1* and C57BL/6 mice during development.     

Comparative study of copper and zinc metabolism in cattle and camel

At an experimental farm, five camels and five cows were fed a similar basal diet for 6 mo. They received oral trace element supplementation for 3 mo (day 22–112). This supplementation included zinc, copper, selenium, managanese, iodine, and cobalt, and corresponded to twice the requirements generally recommended for cows. Plasma copper and zinc concentrations were significantly lower in the camels (61 μg/100 mL for copper and 38 μg/100 mL for zinc) than in the cows (111 and 83, respectively). The supplementation had no effect on plasma zinc concentration in the camels in spite of the low observed values in this species. Liver copper concentration at the beginning of the trial was lower in the camels (9 ppm) than in the cows (35 ppm), and stayed at lower levels during the entire supplementation period. There was no clear difference in fecal excretion of copper and zinc between the camels and the cows. The results suggested that trace element requirements are lower in camels than in cows and that camels regulate their plasma zinc concentration at a very low level (<40 μg/100 mL).     

Changes in tissue adenylates and water content of bluegill, Lepomis macrochirus, exposed to copper

Bluegill were exposed to copper (2–0 mg/1⁻¹ unfiltered) for 24, 48, 72 or 96 h at 24° C. This concentration approximated the 96 h LC20. Water content of liver increased 4–8% after 24 h exposure and muscle 4–6% by 48 h. These changes persisted throughout the 96 h experiments. Copper exposed fish exhibited decreases in muscle ATP, ADP, total adenylates, and energy charge by 48 h. There was a trend toward recovery of ATP with further exposure. Liver ATP of exposed fish was lower than controls at all intervals with the greatest difference evident at 48 h. No significant changes in brain adenylates were observed. Muscle and liver lactic acid was unchanged at 48 h exposure, therefore tissue hypoxia was not the cause of the adenylate changes. It was concluded that copper causes decreases in muscle and liver ATP several days before probable death of copper exposed fish and the changes seen are the result of dilution by increased tissue water, and the copper acting on certain cellular enzymes involved in detoxification and energy metabolism.     

Changes in the intracellular accumulation and distribution of metallothionein in rat liver and kidney during postnatal development

Metallothionein (MT) bound to zinc and copper was detected in high concentration in fetal and newborn rat livers by a cadmium saturation method. The levels of both hepatic zinc and MT remained high for the first 14 days after birth and decreased to adult levels by 24 days of age. There was a direct linear relationship between hepatic metallothionein and zinc concentrations during the first 31 days after birth. The ratio of MT to zinc levels also decreased with age suggesting a rapid degradation of MT during postnatal development. Immunohistochemical localization of MT by peroxidase-antiperoxidase technique, using a specific antibody to MT, showed intense intranuclear staining for MT in fetal and newborn rat liver which persisted until Day 9. The nuclear MT staining decreased with age; at 11 days it was equal both in nucleus and cytoplasm and at 14 days, MT was localized mainly in the cytoplasm, similar to adult rat liver pattern. The intranuclear localization of MT in neonates could be considered as a typical fetal-neonatal morphological pattern and its subsequent presence in the cytoplasm, an adult pattern.     

Extrahepatic tissue copper concentrations in white perch with hepatic copper storage

Hepatic copper storage in man (Wilson's disease), Bedtington and West Highland white terriers, and white perch ( Morone americana ) is characterized by the progressive accumulation of copper in hepatic lysosomes bound to cytoprotective metallothionein. In man, saturation of the liver storage capacity results in the distribution of copper to extrahepatic tissues with multiple organ system dysfunction. To determine if extrahepatic tissue copper concentrations also increase in white perch, copper and zinc levels in liver, brain, heart, gills, serum, and bile were determined by atomic absorption spectrophotometry and compared to striped bass ( Morone saxatilis ). Results showed that brain copper concentrations in. white perch were elevated and significantly correlated with liver copper. Bile and serum copper also increased significantly with liver copper. Copper levels in heart and gill tissues were low. Liver zinc was increased in white perch but not to the same magnitude as copper, and was correlated significantly with liver copper; possibly a non-specific secondary increase related to an overall increase in hepatic metallothionein. Histochemical staining of liver with rubeimc acid for copper was proportional to copper concentrations, and clusters of positive mononuclear cells were also seen in brain and spleen. Foci of macrophages in spleen were also intensely positive with Perl's iron stain which may have been indicative of haemolysis. The patterns of copper distribution seen in white perch present a useful comparative model to study alterations in copper metabolism.     

Comparisons of copper deficiency states in the murine mutants blotchy and brindled. Changes in copper-dependent enzyme activity in 13-day-old mice.

The activity of two copper-dependent enzymes, cytochrome c oxidase and copper, zinc-superoxide dismutase, was determined in six tissues of age-matched (13-day-old) copper-deficient mutant and normal mice. In the two mutants 'brindled' and 'blotchy', brain, heart and skeletal muscle had significant enzyme deficiencies. Cytochrome c oxidase was more severely affected than was superoxide dismutase. In these three tissues the degree of deficiency could be correlated with decreased copper concentration; however, enzyme activity was normal in liver, kidney and lung, despite abnormal copper concentrations in these tissues. In nutritionally copper-deficient mice, all six tissues showed decreased enzyme activity, which was most marked in brain, heart and skeletal muscle, the tissues which showed enzyme deficiencies in the mutants. Analysis in vitro of cytochrome c oxidase (temperature coefficient = 2) at a single temperature was found to underestimate the deficiency of this enzyme in hypothermic copper-deficient animals. Cytochrome c oxidase deficiency may therefore be sufficiently severe in vivo to account for the clinical manifestations of copper deficiency. An injection of copper (50 micrograms of Cu+) at 7 days increased cytochrome c oxidase activity by 13 days in all deficient tissues of brindled mice, and in brain and heart from blotchy mice. However, skeletal-muscle cytochrome c oxidase in blotchy mutants did not respond to copper injection. Cytochrome c oxidase activity increased to normal in all tissues of nutritionally copper-deficient mice after copper injection, except in the liver. Hepatic enzyme activity remained severely deficient despite a liver copper concentration three times that found in copper-replete controls. Superoxide dismutase activity did not increase with treatment in either mutant, but its activity was higher than control levels in nutritionally deficient mice after injection. This difference is probably due to sequestration of copper in mutant tissue such as kidney, but a defect in the copper transport pathway to superoxide dismutase cannot be excluded.     

Distribution of nickel,zinc, and copper in rat organs after oral administration of nickel(II) chloride

The distribution of Ni administered as NiCl₂ · 6H₂O in the drinking water (300 and 1200 ppm Ni for 90 d) was studied using male Wistar rats. Next, the effect of Ni on the concentration of zinc (Zn) and copper (Cu) in selected organs and serum was measured. The metals were analyzed in the liver, kidney, lung, spleen, brain, and serum by electrothermal (Ni) or flame (Zn, Cu) atomic absorption spectrophotometry. The results indicate that exposed rats drank less nickel solutions than the volume of water drunk by controls, but there was no mortality of animals. In comparison to control animals, a very high increase in Ni levels was found in the kidney and then lung and serum of all exposed rats. In the liver, spleen, and brain, the metal accumulation was lower. A directly proportional relation between the nickel intake and its deposition was observed in the collected organs and in the serum. The metal level did not change significantly in the course of exposure (the first analysis was after 30 d). The administration of 300 ppm Ni did not affect the zinc and copper concentration in studied organs, except the serum, where zinc content was significantly reduced. At a dose of 1200 ppm Ni, these metals were found to be depressed in the liver, kidney, serum (zinc), and copper in the kidney.     

Sparing effect of microbial phytase on zinc supplementation in maize-soya-bean meal diets for chickens

The experiment was conducted to evaluate the sparing effect of microbial phytase on the need for dietary zinc supplementation in chicks. A maize–soya-bean meal basal diet, containing 33 mg of zinc and 16 mg of copper per kg, supplemented with 0, 6, 12, 18, 24, 30 or 60 mg of zinc as sulphate per kg or with 250, 500, 750 or 1000 units (FTU) of microbial phytase (3-phytase from Aspergillus niger, Natuphos®) per kg was given to 1-day-old chicks for 20 days. Sixteen chicks placed in individual cages were assigned to each diet except the unsupplemented basal diet which was assigned to 32 cages. Actual range of phytase supplementation was 280 to 850 FTU per kg diet. Growth performance was not affected by microbial phytase. Chicks given the unsupplemented basal diet and the basal diet supplemented with 60 mg of zinc per kg displayed similar performance. Bone weight, bone ash, liver weight and liver dry matter were independent (P > 0.1) of zinc and phytase supplementations. Plasma, bone and liver zinc concentrations increased linearly (P < 0.001) and quadratically (P < 0.001; P < 0.001 and P < 0.05, respectively) with zinc added. Plasma zinc tended to increase linearly (P = 0.07) and bone zinc increased linearly (P < 0.01) with phytase added but no quadratic response was detected (P > 0.1). Liver zinc was unresponsive to phytase added (P > 0.1). Liver copper decreased linearly (P < 0.001) and quadratically (P < 0.01) with zinc supplementation. Mathematical functions were fitted to the responses of plasma and bone zinc to zinc and phytase added and used to calculate zinc equivalency values of phytase. The models included a linear plateau response to zinc added and a linear response to phytase added. In diets without phytase, plasma and bone zinc concentrations were maximised for a dietary zinc concentration of 55 and 51 mg/kg, respectively. Over the range of 280 to 850 FTU, 100 FTU was equivalent to 1 mg of zinc as sulphate. Consequently, in a maize–soya-bean meal chicken diet formulated to contain 60 mg zinc per kg, zinc ingested, and in turn, zinc excreted may be reduced by around 10% if the diet contains 500 FTU as Natuphos® per kg.     

Development of copper deficiency in neonatal mice

Dietary copper (Cu) deficiency was produced in Swiss albino mice to determine the temporal relationship between depletion of Cu and changes in the cardiovascular and nervous system. Dams were placed on a Cu-deficient diet 4 days after parturition. Half the dams were provided with deionized water and their offspring are referred to as Cu-deficient (-Cu). Half the dams were given cupric sulfate in their drinking water (20 microg Cu/mL) and their offspring are referred to as Cu-adequate (+Cu). At 6 weeks of age a sample of the -Cu mice were repleted with CuSO(4). Mice were sampled 1 day after birth and at weekly intervals for 7 weeks. Both +Cu and -Cu mice grew at the same rate: birth weight increased 16-fold at 6 weeks of age. Liver Cu more than doubled between 1 and 7 days of age. At 2 weeks of age -Cu mice were anemic (lower hematocrit and hemoglobin) and had lower liver Cu and plasma ceruloplasmin activity compared to +Cu mice. Liver Fe was not elevated in -Cu mice until 2 weeks after anemia developed. At weaning first signs of altered catecholamine metabolism included elevation of dopamine in both heart and spleen. Norepinephrine concentrations and content, in contrast, were not both lowered in -Cu mice until 5 weeks of age. Heart weight was first elevated in -Cu mice at 6 weeks of age and relative weight (mg/g body wt) at 4 weeks of age. Liver Cu concentration was lower in 1-week repleted mice than in +Cu mice. Anemia preceded the development of cardiac hypertrophy and altered catecholamine levels in -Cu mice.     

Gestational zinc deficiency amplifies the regulation of metallothionein induction in adult mice

To determine if prenatal zinc deficiency has a persistent effect on metallothionein (MT) regulation, Swiss-Webster mice were mated and fed a diet containing either control (100 micrograms Zn/g) or low levels of zinc (5 micrograms Zn/g) from Day 7 of gestation to parturition. After birth all mice were given the control diet. Liver zinc and MT levels were 50% lower in newborn pups from dams fed the low zinc diets than in control pups. In control pups, liver zinc and MT concentrations were relatively stable during the first week of postnatal life. In contrast, in pups prenatally deprived of zinc, liver levels of zinc and MT increased such that by Day 3 of postnatal life, the levels were not significantly different from controls. At Day 56, serum IgM concentrations were significantly lower in the low zinc offspring. Liver zinc concentrations in the two groups of mice were similar at Day 70 postnatal, and in both groups liver MT levels were below detection limits. However, when Day 70 mice were given zinc injections to stimulate MT synthesis, the prenatally zinc deprived offspring showed markedly higher liver MT levels than did control mice given similar injections, despite similar liver zinc concentrations in the two groups. These results show that prenatal zinc deficiency has pronounced effects on postnatal MT metabolism which can persist into adulthood.