Liver copper content of rats hypo- or hyperresponsive to dietary cholesterol

The question addressed is whether cholesterol intake reduces the hepatic copper content in rats. For this purpose we have compared the hepatic copper content of two selected rat inbred strains after feeding the animals a control or a high fat, high cholesterol diet. One strain was dietary cholesterol resistant (SHR/OlaIpcv), whereas the other strain was susceptible to dietary cholesterol (BN-Lx/Cub). Dietary cholesterol-susceptible rats have a lower baseline hepatic copper content when compared with their resistant counterparts. The consumption of a hypercholesterolemic diet decreased the liver copper concentration (expressed in microg/g dry weight) to about the same extent in both strains. However, dietary cholesterol did not reduce the absolute (expressed as microg/whole liver) and relative (expressed as microg/whole liver/100 g body weight) copper store of rats. The decrease of liver copper concentration after the high fat, high cholesterol diet is probably not caused by a decrease in whole hepatic copper content, but rather due to dietary-induced hepatomegaly.     

铜尾矿库区狗牙根根际土壤铜的形态变化

通过野外调查和室内分析,对安徽省铜陵市铜尾矿库区狗牙根根际土壤Cu的形态进行了研究．结果表明,尾矿库区狗牙根根际与非根际土壤Cu大部分为矿物态Cu,交换态Cu含量偏低．与非根际土壤相比,狗牙根根际土壤pH值下降,有机质含量显著增加．随着狗牙根的生长,根际土壤有机结合态Cu和交换态Cu含量显著增加,其占土壤总Cu量的比例分别增加7．89％和超过5％,碳酸盐结合态Cu和铁锰氧化物结合态Cu含量则有所下降．狗牙根生长促进了根际土壤Cu形态的转化,提高了Cu在土壤中的迁移能力,加之狗牙根的吸收作用,其根际土壤Cu含量显著降低．     

INTERACTIVE EFFECTS OF COPPER AND SILICIC ACID ON RESTING SPORE FORMATION AND VIABILITY IN A MARINE DIATOM1

The toxic effects of copper on resting spore formation and viability in the marine diatom Chaetoceros protuberans Lauder were determined both with and without silicic acid added to the medium. With silicic acid available, partial inhibition of resting spore formation occurred only at the highest cupric ion activity (pCu 8.6), while the percentage of cells forming spores at pCu's 10.2 and 11.3 was nearly the same as in the controls. Without silicic acid added to the medium, sporulation was completely inhibited at pCu 8.6 and greatly inhibited, at pCu 10.2. At pCu 11.3 and in the controls, the rate of spore formation was less than 50%. The results indicate that the inhibition of resting spore formation by copper is related to the concentration of silicic acid available to cells of C protuberans. This is consistent with previous studies which show that copper toxicity during vegetative growth involves interference with silicification in diatoms and is a Junction of the silicic acid concentration of the medium. Viable resting spores of C. protuberans were still present in cultures following exposure to elevated copper concentrations during a 100-day incubation period. This indicates that resting spores can serve to enhance diatom survival in areas polluted by heavy metals.     

Membrane-targeted strategies for modulating APP and Aβ-mediated toxicity

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by numerous pathological features including the accumulation of neurotoxic amyloid-β (Aβ) peptide. There is currently no effective therapy for AD, but the development of therapeutic strategies that target the cell membrane is gaining increased interest. The amyloid precursor protein (APP) from which Aβ is formed is a membrane-bound protein, and Aβ production and toxicity are both membrane mediated events. This review describes the critical role of cell membranes in AD with particular emphasis on how the composition and structure of the membrane and its specialized regions may influence toxic or benign Aβ/APP pathways in AD. The putative role of copper (Cu) in AD is also discussed, and we highlight how targeting the cell membrane with Cu complexes has therapeutic potential in AD.     

The relationship between established coronary risk factors and serum copper and zinc concentrations in a large Persian Cohort

IntroductionThe relationship between demographic and biochemical characteristics, including several established coronary risk factors, and serum copper and zinc was assessed in a large Iranian population sample.Materials and methodsA group of 2233 individuals, 15–65 years of age [1106 (49.5%) males and 1127 (50.5%) females] was recruited from residents of the Greater Khorasan province in northeast of Iran. Demographic data were collected using questionnaires. Coronary risk factors were determined using standard protocols, and trace elements were measured in serum using atomic absorption spectroscopy.ResultsDegree of glucose tolerance and smoking habit were not associated with serum zinc and copper levels. Serum copper levels were significantly higher in obese and hypertensive than in normal subjects (p<0.001). In the whole group and for the female subgroup, serum zinc (p<0.01) and copper (p<0.001) were both significantly lower in individuals with normal versus high levels of low-density lipoprotein cholesterol.A strong positive correlation was found between serum copper and body mass index (BMI) (r=0.85, p<0.001). Weaker positive associations were found between serum copper and calculated 10 years’ coronary risk (r=0.11, p<0.001). Serum zinc/copper ratio was strongly inversely associated with calculated 10 years’ coronary risk (r=?0.10, p<0.001). The partial Eta squared (PES) values for factors determining serum zinc were hypertension (0.007, p=0.01) and BMI (0.004, p=0.01); and for serum copper, they were gender (0.02, p=0.001), hypertension (0.004, p=0.009), and 10 years’ coronary risk for men (0.003, p=0.03) and women (0.002, p=0.07).ConclusionSignificant associations between serum trace element concentrations and several coronary risk factors, including calculated 10 years’ coronary risk scores, were found.     

Nickel(II)-substituted azurin I from Alcaligenes xylosoxidans as characterized by resonance Raman spectroscopy at cryogenic temperature

Metal-substituted blue copper proteins (cupredoxins) have been successfully used to study the effect of metal-ion identity on their active-site properties, specifically the coordination geometry and metal–ligand bond strengths. In this work, low-temperature (77 K) resonance Raman (RR) spectra of the blue copper protein Alcaligenes xylosoxidans azurin I and its Ni(II) derivative are reported. A detailed analysis of all observed bands is presented and responsiveness to metal substitution is discussed in terms of structural and bonding changes. The native cupric site exhibits a RR spectrum characteristic of a primarily trigonal planar (type 1) coordination geometry, identified by the ν(Cu–S)_Cys markers at 373, 399, 409, and 430 cm⁻¹. Replacement of Cu(II) with Ni(II) results in optical and RR spectra that reveal (1) a large hypsochromic shift in the main (Cys)S → M(II) charge-transfer absorption from 622 to 440 nm, (2) greatly reduced metal–thiolate bonding interaction, indicated by substantially lower ν(Ni–S)_Cys stretching frequencies, (3) elevation of the cysteine ν(C _β –S) stretching, amide III, and ρ _s(C _β H₂) scissors vibrational modes, and (4) primarily four-coordinated, trigonally distorted tetrahedral geometry of the Ni(II) site that is marked by characteristic ν(Ni–S)_Cys stretching RR bands at 347, 364, and 391 cm⁻¹. Comparisons of the electronic and vibrational properties between A. xylosoxidans azurin I and its closely structurally related azurin from Pseudomonas aeruginosa are made and discussed. For cupric azurins, the intensity-weighted average M(II)–S(Cys) stretching frequencies are calculated to be ν(Cu–S)_iwa = 406.3 and 407.6 cm⁻¹, respectively. These values decreased to ν(Ni–S)_iwa = 359.3 and 365.5 cm⁻¹, respectively, after Ni(II) → Cu(II) exchange, suggesting that the metal–thiolate interactions are similar in the two native proteins but are much less alike in their Ni(II)-substituted forms.     

金属离子对漆斑菌产胆红素氧化酶的影响

比较了漆斑菌在8种液体培养基中胆红素氧化酶(BOX)产量,发现马铃薯液体培养基(PDB)是最适宜漆斑菌产BOX的培养基。研究了8种常见金属离子对漆斑菌产酶的影响,结果表明钠离子、铜离子可以明显促进BOX产量提高,铜离子效果最强,随着铜离子浓度增加,BOX酶产量可进一步提高,但高浓度的铜离子(1mmol.L-1)会抑制酶产量增加。     

Hitchhiking of Cu/Zn Superoxide Dismutase to Peroxisomes – Evidence for a Natural Piggyback Import Mechanism in Mammals

Most newly synthesized peroxisomal proteins are imported in a receptor-mediated fashion, depending on the interaction of a peroxisomal targeting signal (PTS) with its cognate targeting receptor Pex5 or Pex7 located in the cytoplasm. Apart from this classic mechanism, heterologous protein complexes that have been proposed more than a decade ago are also to be imported into peroxisomes. However, it remains still unclear if this so-called piggyback import is of physiological relevance in mammals. Here, we show that Cu/Zn superoxide dismutase 1 (SOD1), an enzyme without an endogenous PTS, is targeted to peroxisomes using its physiological interaction partner 'copper chaperone of SOD1' (CCS) as a shuttle. Both proteins have been identified as peroxisomal constituents by 2D-liquid chromatography mass spectrometry of isolated rat liver peroxisomes. Yet, while a major fraction of CCS was imported into peroxisomes in a PTS1-dependent fashion in CHO cells, overexpressed SOD1 remained in the cytoplasm. However, increasing the concentrations of both CCS and SOD1 led to an enrichment of SOD1 in peroxisomes. In contrast, CCS-mediated SOD1 import into peroxisomes was abolished by deletion of the SOD domain of CCS, which is required for heterodimer formation. SOD1/CCS co-import is the first demonstration of a physiologically relevant piggyback import into mammalian peroxisomes.     

PHYTOEXTRACTION OF METAL POLLUTED SOILS AROUND A Pb-Zn MINE BY CROP PLANTS

In order to assess their practical capability for the absorption and accumulation of Pb, Zn, and Cu, five common crop plants, i.e. maize (Zea mays), sunflower (Helianthus annuus), canola (Brassica napus), barley (Hordeum vulgare) and White lupine (Lupinus albus) were tested in pot experiments using six soil samples taken from mine tailings, pasture and arable soils around an old Pb-Zn mine in Spain. Metal concentration ranges of the soils were 76.2–785 mg kg^?1, 127–1652 mg kg^?1, and 12.4–82.6 mg kg^?1 for Zn, Pb, and Cu, respectively. With the exception of the highest polluted sample, soil total metal concentration did not influence significantly biomass yields of each crop for the different growth substrates. The order found for the total metal accumulation rate (TMAR) in the crops was Zn>>Pb > Cu, with maize reaching the highest metal concentrations. Pb root concentrations were markedly higher than those of shoots for all the crops, while Zn and Cu were translocated to shoots more efficiently. Concentrations of metals extracted by EDTA and BCR sequential extraction were well correlated, in general, with both root metal content and TMAR. CaCl₂-extracted Zn was well correlated with root concentrations, TMAR and, in some cases, with shoot contents. Our study showed that the test crops were not feasible to remediate the heavily or moderately contaminated soils studied here in order to achieve the total metal soil concentrations required by the current European laws.