Copper transporter 1, metallothionein and glutathione reductase genes are differentially expressed in tissues of sea bream (Sparus aurata) after exposure to dietary or waterborne copper

The high affinity copper transporter 1 (Ctr1), metallothionein (MT) and glutathione reductase (GR) are essential for copper uptake, sequestration and defense respectively. Following rearing on a normal commercial diet (12.6±0.2 mgKg-1Cu), sea bream were fed an experimental control diet lacking mineral mix (7.7±0.3 mgKg-1Cu), an experimental diet enhanced with Cu (135±4 mgKg-1 Cu) or an experimental diet (7.7±0.3 mgKg-1Cu) while exposed to Cu in water (0.294±0.013mgL-1). Fish were sampled at 0, 15 and 30 d after exposures. Fish fed the Cu-enhanced experimental diet showed lower levels of expression of Ctr1 in the intestine and liver compared to fish fed control experimental diets, whilst Ctr1 expression in the gill and kidney was unaffected by excess dietary Cu exposure. Waterborne Cu-exposure increased Ctr1 mRNA levels in the intestine and the kidney compared to experimental controls. Excess dietary Cu exposure had no effect on levels of metallothionein (MT) mRNA, and the only effect of dietary excess Cu on glutathione reductase (GR) mRNA was a decrease in the intestine. Both MT mRNA and GR were increased in the liver and gill after waterborne Cu exposure, compared to levels in fish fed experimental control low Cu diets. Thus, Ctr1, MT and GR mRNA expression in response to excess Cu is dependent on the route of exposure. Furthermore, the tissue expression profile of sea bream Ctr1 is consistent with the known physiology of copper exposure in fish and indicates a role both in essential copper uptake and in avoidance of excess dietary and waterborne copper influx

Trace elements in unconventional animals: A 40-year experience

The role of trace elements in animal health has attracted increasing interest in recent years. The essentiality and toxicity of these elements have been extensively investigated in humans, laboratory animal models and partially in domestic animals, whereas little is known about trace element metabolism in most living organisms. Forty years ago our research started on Cd metabolism in molluscs, thereafter expanding to Zn, Cu, and Fe metabolism in many unconventional animal species of veterinary interest. This review summarizes the main results obtained over this long period of time: some of the findings are original and have not been published to date. They are discussed in more detail and compared with data obtained in conventional animals, including man

Total Plasma Magnesium In Healthy And Critically Ill Foals

Abnormalities in total Mg (tMg) concentration in plasma and/or serum are common in critically ill humans, and the association with increased mortality has been documented in several clinical studies in adults and newborns with hypoxic-ischemic encephalopathy. Abnormalities in tMg were studied in hospitalized dogs, cats, and adult horses. Newborn foals were scarcely studied with regard to Mg concentration. The aims of the present study were: (1) to compare two analytical methods for the determination of tMg in plasma: the automated colorimetric method and the atomic absorption spectrometry; (2) to measure plasma tMg in healthy foals during the first 72 hours after birth and in sick foals during the first 72 hours of hospitalization; (3) to compare total plasma Mg concentration among healthy foals, foals affected by perinatal asphyxia syndrome (PAS), prematurity and/or dismaturity, and sepsis; (4) to evaluate tMg plasma concentration in surviving and non-surviving foals. One hundred seventeen foals were included in the study: 20 healthy and 97 sick foals. The automated method used in clinical practice probably overestimates plasma tMg. Due to its higher sensitivity and specificity, the atomic absorption spectrometry should be considered the method of choice from an analytical point of view, but requires an instrumentation not easily available in any laboratory and specific technical skills and competencies. Plasma tMg in healthy foals were included in the range 0.52 to 1.01 mmol/L and did not show any time-dependent change during the first 72 hours of life. In sick foals, tMg evaluated at T0 was statistically higher than tMg measured at subsequent times. Foals affected by PAS had a tMg at T0 significantly higher (P < 0.01) than healthy, septic, and premature and/or dysmature foals. The. t test found significantly higher (P < 0.01) plasma tMg measured at T0 in non-surviving than in surviving foals. Plasma tMg could be a useful parameter for the diagnosis of PAS and the formulation of the prognosis in critically ill foals

X-ray absorption studies of the local environment of zinc ions bound to the bacterial photosynthetic reaction center

Binding of transition metal ions to the reaction center (RC) protein of the photosynthetic bacterium Rhodobacter sphaeroides slows the light-induced electron and proton transfer to the secondary quinone, QB (Utschig et al., 1998, Biochemistry 37, 8278; Paddock et al., 1999, Proc. Natl. Acad. USA 96, 6183). On the basis of X-ray diffraction (XRD) at 2.5 A ° resolution a site has been identified at the protein surface which binds Cd(II) or Zn(II). Both metal ions binds to the same cluster formed by AspH124, HisH126 and HisH128. A water molecule was also proposed to interact with the Zn (Axelrod et al., 2000, Proc. Natl. Acad. Sci. USA 97, 1542). Recent data suggest that inhibition of proton transfer by Cd(II) is predominantly a consequence of competing with protons for binding to HisH126 and HisH128, thus hampering the function of these residues as proton donor/acceptors along the proton pathway to the QB site (Paddock et al., Biochemistry 42,9626, 2003). Determination of the local structure of the bound metal ions is expected to contribute significantly to elucidate the details of the inhibition mechanism. For this reason we performed Zn K-edge X-ray absorption measurements on Zn-doped RCs embedded into polyvinyl alcohol films at both room and liquid nitrogen temperature. Data analysis has been performed using ab-initio simulations and multiparameter fitting; structural contributions up to the fourth coordination shell and multiple scattering paths (involving three atoms) of significant amplitude have been included. Results for complexes characterized by a Zn to RC stoichiometry close to 1 indicate that Zn binds two O and two N atoms in the first coordination shell. The two N atoms come from His, and only one of the two O atoms comes from an amino acid (Asp or Glu); the second O atom belongs to a water molecule. Complexes characterized by approximately two Zn ions per RC show a second structurally distinct binding site, involving three N and one O atom, all coming from nonaromatic residues. The results obtained for the higher affinity site nicely fit the coordination proposed on the basis of XRD data. The second binding site, revealed by our investigation on noncrystalline samples, is most probably located in a more disordered domain of the RC protein and might have a hitherto not appreciated role in charge transfer inhibition