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1.
Copper transport and accumulation were studied in virgin and lactating C57BL/6 mice, with and without expression of ceruloplasmin
(Cp), to assess the importance of Cp to these processes. One hour after i.p. injection of tracer 64Cu, liver and kidney accounted for 80% of the radioactivity, and mammary gland 1%, while in lactating Cp+/+ mice 2–4 days
post partum, uptake by mammary gland was 9-fold higher and that of liver and other organs was decreased, with 64Cu rapidly appearing in milk. Parallel studies in Cp−/− mice (siblings from same colony) gave virtually identical results.
However, their milk contained less 64Cu, and actual copper contents determined by furnace atomic absorption were less than half those for milk from normal dams.
Liver copper concentrations of pups born to Cp−/− dams also were half those of pups from wild type dams. Copper in pup brains
was unaffected; but iron concentrations were reduced. We conclude that absence of Cp, while not affecting entry of exchangeable
copper from the blood into the mammary gland, does have a significant effect on the availability of this metal to the newborn
through the milk and in the form of stores accumulating in gestation. 相似文献
2.
The influence of dietary copper, iron, and ascorbic acid on iron utilization was examined in a 2×2×2 factorial experiment.
Male Sprague-Dawley weanling rats were fed copper-deficient (Cu-, 0.42 μg Cu/g) or copper-adequate (Cu+, 5.74 μg Cu/g) diets
that contained one of two levels of iron (38 or 191μg Fe/g) and ascorbic acid (0 or 1% of the diet). These eight diets were
fed for 20 d, and rats received an oral dose of 4 μCi iron-59 on d 15. Compared to Cu+ rats, the Cu− rats had 27% lower hemoglobin
levels with 45, 59, and 65% lower cytochrome c oxidase (CCO) activities in the liver, heart, and bone marrow, respectively
(p<0.0001). High dietary iron or ascorbic acid did not alter hemoglobin in Cu+ rats. However, hemoglobin was 23% lower in Cu−
rats fed the highest, rather than the lowest levels of iron and ascorbic acid. Liver CCO was decreased (p<0.02) in Cu− rats fed high iron. Among Cu− rats, ascorbic acid did not influence CCO but decreased hemoglobin by 17% (p<0.001), reduced the percentage of absorbed iron-59 in the erythrocytes by 91% (p<0.05) and depressed the percentage apparent absorption of iron (p<0.05). These results suggest that the effects of elevated dietary iron and ascorbic acid on iron utilization are influenced
by copper status. 相似文献
3.
Pyatskowit JW Prohaska JR 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2008,147(3):316-323
Iron homeostasis depends on adequate dietary copper but the mechanisms are unknown. Mice (Mus musculus) and rat (Rattus norvegicus) offspring were compared to determine the effect of dietary copper deficiency (Cu-) on iron status of plasma, liver, brain and intestine. Holtzman rat and Hsd:ICR (CD-1) outbred albino mouse dams were fed a Cu- diet and drank deionized water or Cu supplemented water. Offspring were sampled at time points between postnatal ages 13 and 32. Cu- rat and mouse pups were both anemic, but only rat pups had lower plasma and brain iron levels. Plasma iron was lower throughout the suckling period in Cu- rats but not Cu- mice. Cu- mice derived from dams restricted of Cu only during lactation were also severely anemic without hypoferremia. Intestinal metal analysis confirmed that Cu- pups had major reductions in intestinal concentration of Cu, increased Fe, and normal Zn. However, whole mouse (less the intestine) analysis demonstrated normal content of Fe indicating that the limitation in iron transport by intestinal hephaestin had no consequence to total iron reserves of the mouse. Further research will be needed to determine the reason Cu- mice were anemic since the "ferroxidase" hypothesis does not explain this phenotype. 相似文献
4.
Prohaska JR Broderius M 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2006,143(3):360-366
In an attempt to identify a sensitive and improved marker of mammalian copper status during neonatal development experiments compared two plasma cuproenzymes, peptidylglycine alpha-amidating monooxygenase (PAM ), an enzyme involved in peptide posttranslational activation, to ceruloplasmin (Cp), a ferroxidase involved in iron mobilization. Dietary Cu deficiency (Cu-) was studied in dams and offspring at postnatal age 3 (P3), P12, and P28. Rodent Cp activity rose during lactation whereas PAM activity fell. Reduction in Cp activity was more severe than reduction in PAM activity in Cu- offspring and dams. Cp activity was greater in rats than mice whereas PAM activity was similar in adults but greater in mouse than rat pups. Both cuproenzymes changed during neonatal development and when dietary copper was limiting. With proper controls, each enzyme can be used to assess copper status. 相似文献
5.
Prohaska JR 《The Journal of nutritional biochemistry》1990,1(8):415-419
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. 相似文献
6.
Chronological changes in tissue copper, zinc and iron in the toxic milk mouse and effects of copper loading 总被引:1,自引:0,他引:1
Katrina J. Allen Nicole E. Buck Daphne M. Y. Cheah Sophie Gazeas Prithi Bhathal Julian F. B. Mercer 《Biometals》2006,19(5):555-564
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. 相似文献
7.
Lastra MD Saldívar L Martínez K Munguía N Márquez C Aguilar AE 《Biological trace element research》2005,105(1-3):205-214
Severe matermal zinc deficiency has a devastating effect on pregnancy outcome. Studies of humans and experimental animals
show that matermal zinc deficiency can cause infertility, prolonged labor, intrauterine growth retardation, teratogenesis,
severe immunological deficiencies, or fetal death. The additional need for zinc during pregnancy can be met by an increase
in zinc intake. An increase in zinc supplements, when excessive, can cause a decrease in copper. Therefore, it is important
to determine the zinc and copper concentrations in embryonic tissue in experimental models and their relationship with embryo
number and viability. BALB/c mice were divided into groups according to zinc oral supplementation and gestational age. Phagocytosis
was assesed in peritoneal macrophages from dams. The zinc and copper concentrations were obtained by inductively coupled plasma-optical
emission spectrometry. Zn and Cu data concentrations in all the analyzed samples were above the detection limits. No spectral
interferences were found in both elements (standard reference material was used).
Zinc concentrations show a tendency to increase in embryos (14 gestational days and 21 gestational days) supplemented with
zinc. Copper concentrations showed a noticeable tendency to diminish (36% and 27%, respectively) in the same period. In contrast,
in placenta Zn values were increased by 30% and Cu values were decreased by 26%. We suggest a pivotal role of the placenta
metabolism with its homeostatic mechanisms, in these findings. An important increment appeared in the +Zn embryo number (40%)
relative to control (−Zn) embryos at 21 d gestational age. Embryo mortality was at 6% in +Zn embryos and at 20% in −Zn embryos.
We consider these findings, both in the number and in the viability of +Zn embryos, outstanding. 相似文献
8.
Essential elements, mainly selenium and zinc, were involved in protection against oxidative stress in cells. Oxidation could
lead to the formation of free radicals that have been implicated in the pathogenesis of many diseases, including leukemia.
Leukemia is a neoplastic disease that is susceptible to antioxidant enzyme and essential elements alterations. This study
was undertaken to examine the levels of essential elements, antioxidant enzymes activities, and their relationships with different
types of leukemia. Serum selenium, zinc, and copper concentrations, red blood cell glutathione peroxidase (GPx) activities,
plasma Cu−Zn superoxide dismutase (Cu−Zn SOD) activities and lipid peroxidation (LPO) levels were determined in 49 patients
with different types of leukemia before initial treatment. Serum selenium and zinc concentrations were lower in leukemia patients
than those of controls (p<0.01). Serum copper concentration was higher in leukemia patients than that of controls (p<0.01). The activities GPx and Cu−Zn SOD were significantly increased in leukemia patients, especially with acute leukemia
(AL), acute lymphoid leukemia (ALL), and acute nonlymphoid leukemia (ANLL) (p<0.05), whereas no difference was found between those of chronic myelogeneous leukemia and the controls. The levels of LPO
were normal as controls. Serum selenium concentration was not correlated with GPx, and serum levels of zinc and copper were
not related to Cu−Zn SOD. Serum zinc levels had a negative correlation with the absolute peripheral blast cells, whereas serum
copper had a positive correlation with the absolute peripheral blast cells. Increased GPx and Cu−Zn SOD activities and normal
levels of LPO, which were a protective responses, were an indicator of mild oxidative stress; it mights indicate that the
essentials elements alterations in leukemia patients were mostly dependent on tumor activity. Changes of their levels demonstrated
that there are low selenium, zinc, and high copper status in leukemia patients. The decrease of plasma zinc and increase of
the Cu/Zn ratio could be the index that showed an unfavorable prognosis of acute leukemia. 相似文献
9.
Summary The sorption of phosphorus from nutrient solution and the pH change in the nutrient solution were monitored over a 24 hour
period forTrifolium repens L. cv. ‘Grasslands Huia’ plants. Two different concentration levels of micro-nutrients (B, Cu, Fe, Mn and Zn) and Al formed
the factors of a fractional replicate of a 26 factorial design.
Measurements were made at four time intervals (30 minutes after the plants were placed on the pots, 3 hours, 6 hours and 24
hours later). In addition to phosphorus, fourteen other nutrients (including nitrate and ammonium) were monitored throughout
the experiment.
The sorption of phosphorus was significantly influenced by both aluminium and iron. The effect of aluminium and iron on phosphorus
sorption is attributed to physico-chemical sorption processes involving the root surface. However the effect on the removal
of phosphorus by boron, copper, manganese and zinc was observed only as first order interaction effects —B−Zn, Cu−Zn, Mn−Zn.
Thus these three elements (B, Cu and Mn) only affect phosphorus removal in conjunction with zinc. Aluminium and iron together
had a separate but very significant effect on the removal of phosphorus at most periods throughout the experiment. In contrast,
pH was affected only by aluminium, iron (the pH drop was enhanced) and manganese (the pH drop was decreased) as main effects
independent of the other treatment elements. 相似文献
10.
Experiments performed with Holtzman rats demonstrated that brain iron (Fe) was lower by postnatal day 13 (P13) in pups born and nursed by dams that began copper-deficient (-Cu) treatment at embryonic day 7. Transcardial perfusion of P24-P26 males and females to remove blood Fe contamination revealed that brain Fe was still 20% lower in -Cu than +Cu rats. Estimated blood content of brain for -Cu rats was greater than for +Cu rats; for all groups, values ranged between 0.43 and 1.03%. Using group-specific data and regression analyses, r = 0.99, relating blood Fe to hemoglobin, brain Fe in non-perfused rats in a replicate study was lower by 33% at P13 and 39% at P24 in -Cu rats. Brain extracts from these rats and from P50 rats from a post-weaning model were compared by immunoblotting for transferrin receptor (TfR1). P24 brain -Cu/+Cu TfR1 was 3.08, suggesting that brains of -Cu rats were indeed Fe deficient. This ratio in P13 rats was 1.44, p < 0.05. No change in P50 -Cu rat brain TfR1 or Fe content was detected despite a 50% reduction in plasma Fe. The results suggest that brain Fe accumulation depends on adequate Cu nutriture during perinatal development. 相似文献
11.
The toxic effect of vanadium (sodium metavanadate) during pregnancy and lactation was studied by feeding vanadium to pregnant,
Sprague-Dawley rats at levels of 1 (control) or 75 μg V/g diet through d 21 postpartum, at which time they were killed. Vanadium-fed
dams had lower food intakes and weight gains than controls during pregnancy. Survival until d 21 postpartum was significantly
lower in the vanadium pups compared to controls. In addition, the surviving pups gained less weight than control pups, despite
similar birth weights. On a relative body weight basis, vanadium pups had larger livers, brains, and testes than controls,
suggesting that these animals were developmentally delayed. Vanadium dams and pups had higher concentrations of hepatic vanadium
than controls. Vanadium pups also had higher concentrations of hepatic zinc than control pups. Maternal hepatic zinc concentrations
were not affected by diet. Also, no significant differences in hepatic iron, copper, or manganese concentrations were observed
for either dams or pups. Hepatic thiobarbituric acid reactivity was higher in whole cell and isolated mitochondria for vanadium
dams and pups than for control dams and pups, indicating that these animals may have had higher levels of lipid peroxidation.
This idea was supported by the observation of lower concentrations of reduced glutathione in the livers of vanadium pups compared
to controls. In contrast, kidney and brain glutathione levels were not affected by diet. In conclusion, animals during periods
of rapid growth are susceptible to vanadium toxicity, and increased lipid peroxidation may be one factor underlying this toxicity. 相似文献
12.
Males (n=34) and females (n=23) of long-tailed duck (Clangula hyemalis) collected on the southern coast of the Baltic Sea in winter were studied to determine brain tissue concentration of iron
(Fe), zinc (Zn), copper (Cu), manganese (Mn), and cadmium (Cd). There were no significant differences in the concentration
of metals between males and females, except for Cd, the concentration of which in male brains was twice that of the females.
In the brains of 20 birds (41% male and 26% female), the lead (Pb) concentration exceeded 1 μg/g wet wt. In all the duck brains
examined, Spearman correlation coefficients were significant and positive for Zn−Mn, Cu−Mn, Cu−Fe, and Pb−Fe; a negative correlation
was found for Pb−Zn. Additionally, female brains showed a positive correlation between Pb and Fe. The results obtained were
compared with literature data for diving and nondiving anseriforms and birds of other taxa. It seems that concentration of
heavy metals in the brain tissue of birds reflect natural adaptations (e.g., for diving) as well as effects of environmental
pollution. 相似文献
13.
Copper deficiency leads to anemia but the mechanism is unknown. Copper deficiency also leads to hypoferremia, which may limit erythropoiesis. The hypoferremia may be due to limited function of multicopper oxidases (MCO) hephaestin in enterocytes or GPI-ceruloplasmin in macrophages of liver and spleen whose function as a ferroxidase is thought essential for iron transfer out of cells. Iron release may also be limited by ferroportin (Fpn), the iron efflux transporter. Fpn may be lower following copper deficiency because of impaired ferroxidase activity of MCO. Fpn is also dependent on the liver hormone hepcidin as Fpn is degraded when hepcidin binds to Fpn. Anemia and hypoferremia both down regulate hepcidin by separate mechanisms. Current studies confirmed and extended earlier studies with copper-deficient (CuD) rats that suggested low hepicidin resulted in augmented Fpn. However, current studies in CuD dams failed to confirm a correlation that hepcidin expression was associated with low transferrin receptor 2 (TfR2) levels and also challenged the dogma that holotransferrin can explain the correlation with hepcidin. CuD dams exhibited hypoferremia, low liver TfR2, anemia in some rats, yet no depression in Hamp expression, the hepcidin gene. Normal levels of GDF-15, the putative erythroid cytokine that suppresses hepcidin, were detected in plasma of CuD and iron-deficient (FeD) dams. Importantly, FeD dams did display greatly lower Hamp expression. Normal hepcidin in these CuD dams is puzzling since these rats may need extra iron to meet needs of lactation and the impaired iron transfer noted previously. 相似文献
14.
Rowe SA Kennaway DJ 《American journal of physiology. Regulatory, integrative and comparative physiology》2002,282(3):R797-R804
The rhythm of melatonin in rat milk and the capacity of pups to synthesize and metabolize melatonin were studied. Melatonin was undetectable in milk in the light (< 21 pM), but increased rapidly 2-4 h after dark to peak at 357 +/- 66 pM at mid-dark. Oral or subcutaneous administration of melatonin to 5- and 10-day-old pups resulted in peak plasma melatonin levels 30 min after administration and rapid metabolism. Increases in pineal and plasma melatonin levels at night were detected at 5 and 6 days of age, respectively. Isoproterenol administration (2 microg/g body wt) at mid-light to day 10 pups increased plasma melatonin from 312 +/- 40 pM to 1,298 +/- 160 pM, whereas propranolol (2 microg/g body wt) suppressed nocturnal melatonin secretion from 1,270 +/- 128 pM to 395 +/- 66 pM. The rise of pineal and plasma melatonin in day 10 pups occurred 1 and 2 h after dark onset, respectively, preceding the onset in dams by 3 and 4 h, respectively. Propranolol administration to 2- and 5-day lactating dams inhibited plasma and milk melatonin at night but had no effect on their suckling pups. Transfer of melatonin via the milk is unlikely to provide an entraining signal for rat pups. 相似文献
15.
Effects of Short-Term Over-supplementation of Copper in Milk on Hematology,Serum Proteins,Weight Gain,and Health in Dairy Calves 总被引:1,自引:0,他引:1
Zahra Naseri Mehrdad Mohri Mohammad R. Aslani Ali A. Alavi Tabatabaee 《Biological trace element research》2011,139(1):24-31
Thirty-six calves were used in the present study. The animals were divided equally into three groups (control, test 1, and
test 2). The three groups of calves were homogeneous for parity of dams, sex, and month of birth. From 14 days of age, in
the test 1 group copper as copper sulfate (Merck Co, Germany) was added to each meal of milk at a rate of 10 mg/kg of milk
for 14 days and in test 2 group copper as copper sulfate was added to each meal of milk at a rate of 20 mg/kg of milk for
14 days. Blood samples were taken by jugular venipuncture using disposable syringes at 14 (before Cu supplementation), 30,
60, and 80 days of age. Anticoagulated blood was used for CBC determination. Plane tubes were used for harvesting of serum
and the amounts of total serum protein, albumin, iron, and copper were measured. Calves were weighted at birth and at the
end of trial (day 80) and total gain and mean daily gain were calculated. Days of treatment for ill calves were also recorded
during experiment. Group (treatment) had no significant effect on the amounts of measured parameters except MCH values (p < 0.05) which were significantly lower in test 1 group than other trial groups. Age (sampling time) had significant effects
on the values of most measured parameters (p < 0.05) except WBC, lymphocyte, total protein, and fibrinogen. Significant interactions between sampling time and group were
not seen for any of measured parameters. No significant differences were seen for total weight gain and mean daily gain between
trial groups. Chi-square test revealed no significant difference for the days of treatment between trials groups. 相似文献
16.
V L Richmond 《Laboratory animal science》1992,42(2):190-192
Dietary copper-deficient guinea pig dams (0.8 microgram Cu/g diet) were administered oxytocin to induce delivery of pups, whereas dietary copper-sufficient guinea pig dams (5.8 micrograms Cu/g diet) had uneventful deliveries with 79% surviving pups. The copper-deficient dams carried the fully-formed fetuses to term but did not go into labor unless 0.5 to 6.2 U oxytocin was administered (i.m.). Birth of live pups from copper-deficient dams increased from 28% overall, to 50% if oxytocin was administered in a timely manner. Many pups died of internal hemorrhages probably the result of defective connective tissue crosslinks requiring copper as a co-factor for lysyl oxidase activity. Dietary copper deficiency may be a factor in depressed parturition in the copper-deficient guinea pig dam that responds to administration of exogenous oxytocin for delivery of pups. 相似文献
17.
Cheng J Ma H Fan C Zhang Z Jia Z Zhu X Wang L 《Biological trace element research》2011,144(1-3):570-579
This study was performed to determine the effects of different copper (Cu) sources and levels on plasma superoxide dismutase (SOD), lipid peroxidation, and Cu status of lambs. Fifty Dorper × Mongolia wether lambs (approximately 3?month of age; average BW?=?23.8?±?0.6?kg) were divided into five equal groups each with ten animals according to their weight. Treatments consisted of (1) control (no supplemental Cu), (2) 10?mg Cu/kg DM from Cu-lysine, (3) 20?mg Cu/kg DM from Cu-lysine, (4) 10?mg Cu/kg DM from tribasic copper chloride (Cu(2)(OH)(3)Cl; TBCC), and (5) 20?mg Cu/kg DM from TBCC. The Cu concentration was 6.74?mg/kg DM in the basal diet. Plasma copper concentrations and ceruloplasmin activities were not affected on day?30 by Cu supplementation. Copper supplementation increased plasma and liver copper concentrations and ceruloplasmin activities on day?60. Muscle Cu concentrations were not affected by Cu supplementation. There were no differences in plasma, liver, and muscle Cu concentrations and ceruloplasmin activities between Cu-lysine and TBCC. Liver copper concentrations and plasma ceruloplasmin activities were increased in lambs supplemented with 20?mg Cu/kg DM than in those supplemented with 10?mg Cu/kg DM on day?60. However, copper levels had no effects on Cu concentrations in plasma and muscle. Malondialdehyde (MDA) concentrations were decreased in plasma and liver tissues, but not affected in muscle by Cu supplementation. Plasma SOD activities were increased by Cu supplementation. There were no differences in plasma, liver, and muscle MDA concentrations and plasma SOD activities between Cu sources and levels. These results indicated that Cu supplementation increased plasma SOD activity, lipid oxidative stability, and copper status of lambs, but did not influence lipid oxidative stability in sheep muscle. Cu-lysine and TBCC were of similar availability when offered to finishing sheep. 相似文献
18.
The effect of copper (Cu) deficiency on the reproduction and development in Xenopus laevis was evaluated, culminating in the development of a defined concentration-response relationship. Separate groups of four adult
frog pairs were fed one of three diets for 28 d: (1) low-copper (−Cu); (2) copper supplemented (+Cu); and (3) ASTM standard
beef liver and lung (BLL). Embryos collected from frogs administered the −Cu diet had markedly decreased egg masses and viability
rates and an increased rate of necrosis when compared to the other dietary treatments. Malformations in −Cu larvae included
maldevelopment of the heart, eye, craniofacial region, brain, and notochord. Larvae from adults administered the −Cu diet
showed delayed abnormal hindlimb development, characterized as selective reductive deficiencies distal to the femur, with
poor cartilaginous development. A U-shaped dose-response curve characteristic of nutritional essentiality was developed for
Cu. Overall, these studies indicated that embryos produced from frogs administered a −Cu diet are substantially less viable
than embryos from frogs administered a +Cu or copper-adequate (BLL) diet. 相似文献
19.
Photooxidation of wetland and riverine dissolved organic matter: altered copper complexation and organic composition 总被引:1,自引:0,他引:1
In natural waters, the uptake of transition metals such as copper (Cu) by aquatic biota depends on the activity of the free
cupric ion ({Cu2+}) rather than on total Cu concentration. Thus, an important ecological function of dissolved organic matter (DOM) in aquatic
ecosystems is Cu–DOM complexation, which greatly decreases the {Cu2+}. However, Cu bioavailability is greatly modified by source and environmental history of DOM because DOM affinity for Cu
varies by orders of magnitude among DOM sources; moreover, DOM is photochemically unstable. During 72-h irradiation experiments
at intensities approximating sunlight with DOM from a palustrine wetland and a third-order river, we investigated photooxidative
effects on DOM complexation of Cu as well as spectral and chemical changes in DOM that might explain altered Cu complexation.
Irradiation decreased Cu complexation by riverine DOM, but unexpectedly increased Cu complexation by wetland DOM, resulting
in 150% greater {Cu2+} in riverine DOM at the same dissolved organic carbon concentrations. The specific ultraviolet absorption (SUVa) and humic substances tracked photochemical changes in the conditional stability constants of Cu–DOM complexes, suggesting
that the aromaticity of DOM influences its affinity for Cu. Carbonyl concentration in 13C nuclear magnetic resonance spectra (13C-NMR) covaried directly with Cu binding-site densities in DOM. However, no aspect of Cu–DOM complexation consistently covaried
with fluorophores (i.e., the fluorescence index) or low molecular weight organic acids. Our results suggest that global increases
in UV radiation will affect Cu–DOM complexation and subsequent Cu toxicity depending on light regime as well as DOM source.
Handling editor: K. Martens 相似文献
20.
Andreazza R Okeke BC Pieniz S Brandelli A Lambais MR Camargo FA 《Biological trace element research》2011,143(2):1182-1192
Environmental copper contamination is a serious human health problem. Copper reductase is produced by microorganisms to facilitate
copper uptake by ATPases into the cells increasing copper biosorption. This study assessed the reduction of Cu(II) by cell-free
extracts of a highly copper-resistant bacterium, Pseudomonas sp. strain NA, isolated from vineyard soil contaminated with copper. Both intact cells and cell-free extract of Pseudomonas sp. strain NA displayed substantial reduction of Cu(II). Intact cells reduced more then 80 mg L−1 of Cu(II) from medium amended with 200 mg L−1 of copper after 24 h of incubation. Cell-free extract of the isolate reduced more than 65% of the Cu(II) at initial copper
concentration of 200 mg L−1 after 24 h. Soluble protein production was high at 72 h of incubation at 100 mg L−1 of copper, with more then 60 μg L−1 of total soluble protein in cell-free extract recorded. Cu(II) reduction by isolate NA was increased when copper concentration
increased for both intact cells and cell-free extract. Results indicate that Pseudomonas sp. strain NA produces copper reductase enzyme as the key mechanism of copper biotransformation. 相似文献