Analyses of multivariately determined community matrices using cluster analysis and multidimensional scaling

Linear discriminant analysis was used to compute the p-variate MACARTHUR-LEVINS and Density Overlap measures of niche overlap between all pairs of 24 passerine bird species. The overlap values for the species pairs were then organized into a community matrix for each approach. The relationships inherent in the community matrices were structured by cluster analysis and non-metric multidimensional scaling. Cluster analysis identified the highly related species groups whereas multidimensional scaling demonstrated community wide relationships. In particular, the scaling approach clearly delineated shrub density and ground cover gradients.     

Effects of iron,copper, zinc,calcium, and magnesium on human lymphocytes in culture

The effects of simultaneous changes of calcium, magnesium, iron, copper, and zinc concentrations were evaluated in normal human T and B lymphocytes, cultured in cation-depleted media. Optimal concentrations for thymidine incorporation (TI) in both cell populations were Fe and Zn 15 μM and Cu 5 μM; for t cells Ca 2 mM and Mg 4 mM; for B cells Ca 4 mM and Mg 6 mM. TI decreased with increasing molarity of cations and the decrease was particularly apparent with Cu. Minimal amounts of Ca and Mg (0.5 mM) were necessary for growth, even in presence of optimal concentrations of Fe, Cu, and Zn. Fe and Cu showed synergistic stimulatory effects at low concentrations and synergistic inhibitory effects at high concentrations. Antagonism between Fe and Zn, Cu and Zn, and Ca and Zn was also demonstrated. CD4/CD8 increased with PHA stimulation in presence of Zn, and decreased with ConA stimulation in presence of Zn or Fe. The results demonstrate: (1) the relationship and interdependence of Fe, Cu, and Zn concentrations in modulating the growth of normal lymphocytes; (2) the stimulatory effects of Fe on B cells and Zn on CD8 positive cells; (3) the inhibitory effect of Cu at concentrations lower than those of Fe and Zn; (4) the requirement of Ca and Mg in certain concentration and ratio for the action of the other cations; and (5) the Ca and Mg requirement for the growth of B cells higher than T cells.     

Changes in iron, calcium, magnesium, copper, and zinc levels in different tissues of riboflavin-deficient rats

To clarify the changes of mineral levels in different tissues of riboflavin-deficient rats, Wistar rats were separated into three groups. One group was fed a diet ad libitum that was deficient in riboflavin. The other two were fed either the complete diet that was weight-matched to the riboflavin-deficient group or fed a complete diet ad libitum. In riboflavin-deficient rats, the hemoglobin concentration and riboflavin contents of blood, liver, and kidney were significantly decreased, compared with weight-matched and ad libitum-fed controls. The mineral concentrations of tissues are summarized as follows: The iron (Fe) concentration in the heart, liver, and spleen was decreased in the riboflavin-deficient group compared with the other groups. Calcium (Ca) and magnesium (Mg) concentrations in tibia were decreased in the riboflavin-deficient group compared with the other two groups. Copper (Cu) concentration was increased in the heart and liver when the riboflavin-deficient group was compared with the other groups. Zinc (Zn) concentration was increased in tibia when the riboflavin-deficient group was compared with the other groups.     

Effects of essential divalent metals on carcinogenicity and metabolism of nickel and cadmium

Interactions between the physiologically essential metals calcium, magnesium, and zinc and the carcinogenic metals nickel and cadmium were investigated to help elucidate the mechanisms of action of the carcinogenic metals. Bioassay studies revealed several significant findings, including: (1) the ability of magnesium and calcium to inhibit nickel-induced elevation of pulmonary adenoma incidence in strain A mice; (2) the ability of magnesium, but not of calcium, to prevent cadmium-induced subcutaneous sarcoma formation; and (3) the ability of magnesium, but not of calcium, to inhibit nickel-induced muscle tumor formation. Biochemical studies indicated a direct relationship between the antitumorigenic potential of magnesium and the capacity of this metal to: (1) inhibit nickel and cadmium uptake by the target tissues in vivo; (2) inhibit nickel-induced disturbances in DNA synthesis in vivo; (3) inhibit nuclear and cytosolic uptake of nickel by the target tissue cells in vivo; and (4) inhibit nickel and cadmium binding to DNA in vitro. Calcium, which in most cases did not prevent carcinogenesis, had no consistent influence on the uptake of carcinogenic metals or their biochemical effects in the target tissues. Magnesium and zinc, but not calcium, were also found to attenuate the acute toxic effects of nickel, indicating a possible correlation between prevention of acute effects and reduction in tumorigenicity. Zinc, which antagonizes cadmium tumorigenicity in the rat testis, was found to reduce markedly cadmium uptake into isolated testicular interstitial cells. Also, zinc was found to inhibit strongly cadmium binding to DNA in vitro.     

Role of thiocyanate ion in metallothionein induction and in endogenous distribution of essential elements in the rat liver

Thiocyanate is the major toxic metabolite of hydrogen cyanide, a toxic substance the organism may be exposed to as a result of cigarette smoking or industrial pollution. The complex interactions existing between metals and metallothionein induction are well known. However, the possible role of thiocyanate, which is also an anion, has not been established yet. Considering the interactions between metals and the metallothioneins, in this study the relationship between thiocyanate and the in vivo distribution of hepatic metallothionein and zinc, copper, iron, calcium, magnesium, and manganese are investigated in rats. This study implies that thiocyanate has, to some extent, an effect on the in vivo expression of metallothionein and endogenous distribution of essential elements in rat liver. Elevated levels of metallothionein and changes in hepatic concentrations of essential elements have suggested a role for thiocyanate in cellular metabolism and it might reflect a direct role of thiocyanate on alteration of cellular functional activities.     

Effects of addition of calcium and magnesium salts on ammonia volatilization during manure decomposition

Ammonia volatilization during aerobic decomposition of poultry manure was significantly reduced through additions of calcium and magnesium salts. The percentage reduction in ammonia loss decreased during the 48 day decomposition period from 85–100% in the first 2–3 weeks, to 23–52% at the end of the experiment. The maximum amount of ammonia which was retained (i.e. maximum reduction in ammonia loss) through addition of the chloride salts of Mg²⁺ or Ca²⁺ was independent of the type of cation. However, CaCl₂ released some of the ammonia initially retained as production of CO₂ and NH₃ from the manure decreased after 3 weeks of decomposition, whereas both MgCl₂ and MgSO₄ did not release any of the initially retained ammonia over the 7 week incubation period. Over the entire incubation period MgCl₂ therefore retained more ammonia than CaCl₂. Magnesium sulphate was considerably less effective in retaining ammonia than either chloride salts.     

Electric pulse-induced fusion of mouse lymphoma cells: Roles of divalent cations and membrane lipid domains

Summary Mouse leukemic lymphoblasts (L5178Y) brought into close contact by dielectrophoresis underwent cell fusion following the application of electrical pulses in the presence of electrolytes. The electrically fused cells became spherical after switching off the dielectrophoretic field. Fusion between a cell vitally stained with Janus Green and that with Neutral Red resulted in the homokaryon with a mixed color. Intracellular potentials simultaneously recorded from the two cells located on both sides of the homokaryon were identical. The fusion efficiency was remarkably dependent upon temperature, displaying a discontinuity at about 11°C in the Arrhenius plot. The extracellular application of phospholipase-A₂ or-C suppressed the fusion yield. Thus, it appears that the phospholipid domains play a crucial role in the electric pulse-induced cell fusion. Treatment of the cells with proteolytic enzymes markedly enhanced the fusion yield, presumably due to removing the glycocalix and/or giving rise to fusion-potent, protein-free lipid domains. The presence of millimolar concentrations of divalent cations (irrespective of Mg²⁺ or Ca²⁺) as well as of micromolar concentrations of Ca²⁺ (but not Mg²⁺) was prerequisite to the resealing of membranes suffered from electrical breakdown upon exposure to electric pulses. In addition, extracellular Ca²⁺ (but not Mg²⁺) ions at more than micromolar concentrations were indispensable for the cell fusion.     

The effect of aging on the mineral status of female mice

To clarify the effect of aging on the mineral status of female mice, mineral concentrations in their tissues were determined. Five 2-mo-old, five 6-mo-old, and five 10-mo-old female B10BR mice were fed a commercial diet. Iron, zinc, copper, calcium, magnesium, sodium, and potassium concentrations in the blood, liver, kidney, heart, brain, lung, and spleen of the mice were determined using a flame atomic absorption spectrophotometer. Iron concentrations in the liver, kidney, heart, brain, and spleen increased with age. Significant differences were detected between mice 2 and 6 mo of age and between mice 2 and 10 mo of age. Zinc concentrations in the heart and lung decreased significantly with age. Zinc concentrations in the heart and lung of 10-mo-old mice were significantly lower than those of 2-mo-old mice. It is noteworthy that the copper concentration in the brain of 10-mo-old mice was markedly higher compared with that of younger mice. Calcium accumulation was apparent in the kidney of mice at 10 mo.     

Effect of 2,3,7,8-Tetrachlorodibenzo-p-dioxin on the Hepatic Distribution of Iron,Copper, Zinc,and Magnesium in Rats

The distribution of iron, copper, zinc, and magnesium in hepatic subcellular fractions of male and female rats treated with 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) was determined. Animals received 40 μg TCDD per kilogram per day for three days by mouth (PO) or the vehicle and were killed seven or nine days posttreatment. Iron, copper, zinc, and magnesium were determined by atomic absorption spectroscopy. The iron content of liver from female animals was twofold higher than male animals. The administration of TCDD increased the iron content of mitochondria in female and male rats and decreased iron content of microsomes of both sexes. Significant increases occurred in the copper content of whole liver, mitochondria, and cytosol of male rats and in whole liver and cytosol of female rats. Decreases in the copper content of the microsomes of male rats were observed following TCDD treatment; however, TCDD produced no changes in the zinc content of hepatic subcellular fractions of either sex. The magnesium content of female TCDD-treated rats increased in whole liver, mitochondria, and cytosol, while the magnesium content of microsomes was not altered. With respect to the subcellular distribution of iron, copper, zinc, and magnesium, TCDD produces differential effects. The altered distribution of some cations may contribute to the broad range of effects of TCDD.     

Developmental patterns of aluminum and five essential mineral elements in the central nervous system of the fetal and infant guinea pig

Al is found in the developing conceptus, but little information is available concerning its tissue distribution and its changes in concentration with age. Because Al has affinity for many of the same biological ligands as the essential mineral cations Ca, Mg, Zn, Fe, and Mn, we hypothesized that Al might show a pattern of developmental concentrations that was similar to one or more of these elements in the brain, a major target of Al toxicity. Concentrations of Al, Ca, Mg, Zn, Fe, and Mn were measured in spinal cord, brainstem, cerebellum, and forebrain of guinea pig fetuses on gestation day (GD) 30 and 45, at birth, and on postnatal day (PND) 3, 6, and 12. Dams were fed commercial guinea pig chow, which contained 47 μg Al/g. Tissue Al and Mn were measured with electrothermal atomic absorption spectrophotometry (ETAAS), and the other elements with inductively coupled axial plasma spectroscopy (ICAP-AES). Al concentrations in the brain regions were highest in spinal cord, brainstem, and cerebellum, and decreased during late gestation and lactation. Al did not show marked increases in regional brain concentrations during the final third of gestation as did Fe, Mg, and Zn. In contrast to Fe and Ca, Al did not accumulate in placenta. Al was the only element to show higher concentrations in spinal cord than in any other tissue at birth. In summary, the tissue distribution of Al did not follow that of essential cations as examined in this study.     

Inhibition of intestinal copper absorption by divalent cations and low-molecular-weight ligands in the rat

l-histidine (His) has been shown to enhance the inhibitory effect of zinc on intestinal copper absorption. This study was aimed at examining whether this effect of His was also extended to the interactions of other divalent cations: ferrous iron, tin, and cobalt, using an in vivo perfusion system in rats. Copper absorption and intestinal content of this element significantly decreased in the presence of 2 mM His and ferrous iron. Iron accumulation was greater when His was present than when omitted. A fivefold excess of tin inhibited copper absorption only when His was present. Citrate, at the same concentration as His, had no effect on copper absorption, but hepatic copper levels were increased, as compared to the absence of either His or citrate. Addition of 0.5 or 1.0 mM cobaltous salt plus His resulted in a sharp decrease in copper intestinal absorption, with an increase in intestinal tissue retention. These results confirm earlier findings with zinc and His, and suggest that a general phenomenon, either accelerating the removal of copper from the intestinal lumen or increasing, the retention of this element by the intestinal tissue, is a common feature of the interaction between cations of similar electronic configuration to copper and a high-affinity ligand, such as His.     

Developmental aluminum toxicity in mice can be modulated by low concentrations of minerals (Fe,Zn, P,Ca, Mg) in the diet

Female Swiss Webster mice were fed diets containing 7 (control) or 1000 μg Al/g diet from conception to weaning. Pregnancy weight gain, brith weight, litter size, postnatal mortality, and weaning weight were measured. In different groups, diets low in Fe, Zn, P, or Ca and Mg (CaMg) were used as basal diets, to which Al was added. Relative to controls, who received NRC recommended levels of these nutrients, all diets with marginal essential trace elements impacted development, as demonstrated by effects on birth weight (CaMg, Fe) or weaning weight (Fe, Zn, P). Compared to diets low in Al, the 1000-mg Al/g diet led to reduced weaning weight regardless of the essential element content of the diet. Other end points were influenced by Al only within the basaldiet group; pregnancy weight gain with the low-P diet, litter size with the low-Fe diet, pregnancy completion with the low-Zn diet, and postnatal mortality with the low-CaMg or low-Zn diet. Thus, diets marginal in selected minerals can differentially alter the toxicological profile of developmental Al exposures. A basal diet was also used in which the NRC diet was supplemented with ascorbic acid, which promotes Al absorption. No modification of Al toxicity was seen with ascorbic acid supplementation.     

Short Communication: Ames assay with Salmonella typhimurium TA102 for mutagenicity and antimutagenicity of metallic oxide powders having antibacterial activities

Metallic oxide powders (magnesium oxide, calcium oxide and zinc oxide) having antibacterial activity were examined for their mutagenicity and antimutagenicity by the Ames test with Salmonella typhimurium TA 102. These powders were not mutagenic to the tester strain and reduced the mutagenicity of methylglyoxal.     

Changes in leaf mineral composition and chloroplast proteins induced by K-deficiency and increased UV-B radiation

Solar UV-B radiation increased to 20 % over ambient level at Madurai was given to cowpea (Vigna unguiculata L. cv. Pusa-152) seedlings sufficiently supplied by potassium (0.88 mM K₂SO₄) and K-deficient (0.05 mM K₂SO₄). Leaf mineral composition was significantly changed due to both increased UV-B radiation and K-deficiency imposed independently or jointly for 12 d. A severe reduction in 23 kDa chloroplast protein was seen only in seedlings encountered combined stress. This revised version was published online in July 2006 with corrections to the Cover Date.     

Improving the mineral reserves and protein quality of maize (Zea mays L.) kernels using unique genes

The effects of the maize genes, o ₂ and Mal, on the concentrations of mineral nutrient cations and amino acid levels in mature maize (Zea mays L) kernels of various inbred lines were studied. Previously, the o ₂ gene has been used to improve the protein quality and increase the mineral nutrient content of kernels from some inbred lines. Genotypes possessing the Mal (multiple aleurone layer) gene, contain more than one row of aleurone cells in their kernels and this gene enhances the effect of the o ₂gene on improving kernel protein quality. Incorporating these genes into the maize genome increased accumulation of several mineral nutrients (including Ca, Mg, Zn, Fe, Mn, Zn and Cu) in some of the experimental lines studied. The physiological basis for this increase of mineral nutrients in the kernels is discussed. The effect of the Mal gene on the kernel amino acid composition and protein quality was also examined. Possibly, these genes could be used in combination in breeding programs to improve kernel quality and nutritional value of maize.     

The effect of aging on the mineral status of female SAMP1 and SAMR1

The effect of aging on the status of macrominerals and trace elements in tissues was studied using two strains (SAMP1 and SAMR1) of senescence accelerated mouse. Two-month-old, 6-mo-old, and 10-mo-old female SAMP1 and SAMR1 mice were fed a commercial diet. Iron, zinc, copper, calcium, magnesium, phosphorus, sulfur, sodium, and potassium concentrations in blood, liver, kidney, brain, and tibia of the mice were determined. The copper concentration in the brain was significantly increased with age in SAMP1 and SAMR1. In addition, the brain copper levels in SAMP1 were significantly higher than that in SAMR1 at respective ages. The calcium concentration in the kidney was significantly increased with age, but the copper and phosphorus concentrations significantly decreased with age in SAMP1 and SAMR1. In the liver of SAMR1, all minerals measured in this study except for sodium and potassium were significantly decreased with age. In addition, all mineral concentrations in the liver of 2-mo-old mice in SAMR1 except for copper and sodium were markedly higher than those in SAMP1 of the same age. These results suggest that the genetic factor is related to the age-associated mineral changes in tissues.     

Adsorption ofRhizobium meliloti to alfalfa roots: Dependence on divalent cations and pH

Adsorption ofRhizobium meliloti L5-30 in low numbers to alfalfa (Medicago sativa L.) roots was dependent on the presence of divalent cations, and required neutral pH. Adsorption was proportional to Ca and/or Mg concentrations up to 1.5 mM. Ca was not substituted by Sr, Ba or Mn. Adsorption was abolished and viability decreased at pH6. When lowering pH, higher Ca concentrations were required to attain similar adsorption levels, indicating a marked interactive effect between Ca and H ions. Pretreatment of the roots with Ca and low pH did not affect subsequent adsorption of the bacteria. However, Ca pretreatment ofR. meliloti sustained further adsorption at low Ca levels and low pH substantially affected their ability to adsorb. Low pH appears to affect the stability of binding causing desorption of the previously bound bacteria. The presence of saturating concentrations of heterologousR. leguminosarum bv.trifolii A118, did not prevent the expression of divalent cations and pH requirements, as well as their interaction. Our results suggest that rhizobial binding to the root surface already shows the Ca and pH dependence of alfalfa nodulation, which was generally associated to some event prior to rhizobial penetration of root hairs.     

Effects of seasonal and physiological variations on the serum major and trace element levels in sheep

The aim of this study was to investigate the possible effects of the seasonal and physiological variations on the Cu, Zn, Mg, Fe, Se, Ca, K, Na, Cl, and P concentrations and their relationships with the estradiol and progesterone levels in Sakiz-Ivesi sheep. For this purpose 34 healthy Sakiz-Ivesi crossbreed sheep were divided into two groups. The first group (n=22) was mated and the second group (n=12) was not mated. They were raised under pasture conditions and without any dietary supplementation. Their serum samples were collected four times a year at each season and under each physiologic condition. The periods are 1=early pregnancy (October), 2=late pregnancy (January), 3=lactation (April), and 4=dry season (July). The results of this study indicated that (1) Mg concentrations in serum vary with seasonal variations but not physiological variations, (2) Fe and K concentrations in serum vary only with physiological variations, (3) the Cu concentration changes not only pregnancy but also through some other hormonal changes not caused by pregnancy, (4) Ca, P, and Se concentrations could vary with both physiologic and seasonal variations, (5) Zn, Na, and Cl were almost identical for both groups and altered depending on neither season of the year nor the physiologic status, (6) both increased estradiol level and increased progesterone level can raise Cu levels in serum, and (7) increased serum Ca concentrations are related with increased estradiol and decreased P and Mg levels. These observations suggest that seasonal and physiologic variations and sexual cycle have to be taken into consideration for a correct ***DIRECT SUPPORT *** A02Q2015 00006 interpretation of elements status. If sheep are maintained at pasture conditions, the nutritional requirements must be supplemented during certain periods. Otherwise, it is apparent that this will cause a decline in the total performance of sheep and, consequently, economic lost.     

Metal–ion interactions and the structural organization of Sepia eumelanin

The structural organization of melanin granules isolated from ink sacs of Sepia officinalis was examined as a function of metal ion content by scanning electron microscopy and atomic force microscopy. Exposing Sepia melanin granules to ethelenediaminetetraacetic acid (EDTA) solution or to metal salt solutions changed the metal content in the melanin, but did not alter granular morphology. Thus ionic forces between the organic components and metal ions in melanin are not required to sustain the natural morphology once the granule is assembled. However, when aqueous suspensions of Sepia melanin granules of varying metal content are ultra‐sonicated, EDTA‐washed and Fe‐saturated melanin samples lose material to the solution more readily than the corresponding Ca(II) and Mg(II)‐loaded samples. The solubilized components are found to be 5,6‐dihydroxyindole‐2‐carboxylic acid (DHICA)‐rich constituents. Associated with different metal ions, Na(I), Ca(II) and Mg(II) or Fe(III), these DHICA‐rich entities form distinct two‐dimensional aggregation structures when dried on the flat surface of mica. The data suggest multiply‐charged ions play an important role in assisting or templating the assembly of the metal‐free organic components to form the three‐dimensional substructure distributed along the protein scaffold within the granule.     

Influence of tight junctions on the interaction of salts with lingual epithelia: responses of chorda tympani and lingual nerves

The role of tight junctions in modulating responses from chorda tympani (taste) and lingual (general sensory) nerves are clarified in regard to their responses to salts. Chorda tympani (CT) responses elicited by organic sodium salts require greater Na⁺ concentrations to elicit the same magnitude of response as NaCl. These data can be understood in terms of the organic anions (compared with Cl^–) producing larger liquid-junction potentials across tight junctions between taste cells which, in turn, reduces Na⁺ influx into taste cells via amiloride-inhibitable channels. The anion contribution to the CT response to different Na⁺ salts can be eliminated (or enhanced) by voltage clamping the tongue with negative (with respect to the serosal solution) potentials.Whole nerve recordings from the lingual branch of the trigeminal nerve elicited by NaCl (and other salts) were reversibly inhibited by the tight junction blocker, LaCl₃ These data suggest that small hydrophilic molecules elicit responses from trigeminal fibers by diffusing across tight junctions between epithelial cells and altering the composition of the extracellular space.