Influence of soil waterlogging on subsequent plant growth and trace metal content

Summary The uptake of trace metals by two plant species (French bean and maize) has been measured on two soils subjected to various waterlogging regimes. Uptake of both manganese and iron was increased due to soil waterlogging, although reoxidation of the soil affected iron more than manganese. Zinc and copper uptake was influenced by a species factor; French bean (Phaseolus vulgaris) showed preferential uptake of zinc, whereas maize (Zea mays) took up copper preferentially. Uptake of cobalt by both species was increased due to waterlogging, following the pattern of manganese.The abilities of these species to take up trace metals from soil followed the pattern predicted by selective extraction of soil for manganese, iron and cobalt, but not for zinc and copper.     

Serum trace mineral variations in Nili-Ravi buffaloes suffering with prepartum vaginal prolapse in two different agro-ecological zones of Punjab, Pakistan

The present study was conducted during 2005 and 2006 on 200 Nili-Ravi buffaloes kept in two agroecological zones (irrigated [zone 1] and rain-fed [zone-2]) of Punjab, Pakistan, with the objective to determine the level of trace minerals (Cu, Fe, Zn, Se) in serum of the buffaloes suffering from vaginal prolapse and to compare them with their healthy counterparts. In each zone 50 buffaloes suffering from prepartum vaginal prolapse during their seventh month of gestation were identified through survey. Vaginal prolapse-affected buffaloes belonging to zone 1 were identified as group VPB1 (N = 50), whereas buffaloes belonging to zone 2 were recognized as VPB2 (N = 50). The buffaloes of control group in zone 1 and zone 2 were identified as NCB1 and NCB2, respectively. The blood samples in all four groups of buffaloes were collected three times, i.e., first when these animals were in the eighth month of gestation, second during the eighth to ninth month of gestation, and finally when these animals were in the ninth or later month of gestation. The mean serum copper concentrations in buffaloes of group VPB1 were significantly lower (P < 0.05) in comparison with NCB1 and NCB2, whereas there were nonsignificant differences (P > 0.05) in copper concentrations between VPB1 and VPB2. There was a significant difference (P < 0.05) of iron concentration in VPB1 compared with NCB1 and NCB2. Similarly, VPB2 also had significantly lower (P < 0.05) iron concentrations compared with NCB1 and NCB2. Serum zinc concentrations were significantly lower (P < 0.05) in animals of the VPB1 group when compared with NCB1 and NCB2. Similarly, lower zinc concentrations were observed in VPB2 in comparison with NCB1 and NCB2. There was significantly lower (P < 0.05) zinc concentration in affected buffaloes (VPB1 and VPB2) from the ninth month of gestation to term when compared with those in the eighth to ninth mo of gestation, and with those not yet in the eighth month of gestation. Serum selenium concentration were significantly higher (P < 0.05) in control group buffaloes (NCB1 and NCB2) in comparison with vaginal prolapse-affected buffaloes (VPB1 and VPB2). During different stages of gestation, mean serum selenium concentrations varied nonsignificantly (P > 0.05) within each group of buffalo. Based on information obtained from this study, it was concluded that the low serum concentration of copper and selenium are linked to increased incidence of vaginal prolapse in buffaloes during the last trimester of gestation.     

Effect of zinc fertilization on the mineral nutrition of rices differing in tolerance to zinc deficiency

Summary The effects of four Zn levels on the electrochemical and chemical properties of the soil solution, and on the growth and mineral nutrition of two rice varieties (IR26 and IR34) differing in tolerance to Zn deficiency were studied in the greenhouse using Zn-deficient soils from two locations. A similar experiment was conducted in culture solution to check how Zn addition affects translocation of other nutrients.In both soil and culture solution, plant Zn concentrations alone was not enough to account for varietal tolerance to Zn deficiency. Comparison of nutrient to Zn and shoot to root ratios of nutrients was more useful in determining the possible mechanism of varietal tolerance. IR 34 appeared to tolerate the disorder due to its lower Zn requirement, more efficient Zn translocation and ability to maintain lower Fe/Zn, Cu/Zn, Mg/Zn and P/Zn ratios in the shoot than the more susceptible variety, IR26. This was shown to be due to decreased translocation of Fe, Mg and P to shoots and decreased absorption of Cu by the root in IR34 in culture solution studies. Adding Zn further reduces translocation or absorption of these nutrients and depending on the nutrient supply of the soil, could cause deficiencies or mineral imbalances, especially of Fe, Cu, and P.These observed varietal differences regarding Zn requirement and the interaction of Zn with absorption and translocation of plant nutrients necessitates revision of recommendations for Zn fertilization. There is an inevitable need for Zn application in severely Zn-deficient soils regardless of rice variety. But on marginally Zn-deficient soils especially those low in Fe, Cu, or P, Zn fertilization is not advisable when resistant rice varieties are used.     

An evaluation study of trace element content in colorectal liver metastases and surrounding normal livers by X-ray fluorescence

Background Trace elements are involved in many key pathways involving cell cycle control. The levels of trace metals such as iron, copper, and zinc in colorectal liver metastases have not previously been assessed. Methods The trace element content in snap-frozen cancerous liver tissue from patients who underwent liver resection for colorectal liver metastases was compared with the normal surrounding liver (distant from the cancer) using X-ray fluorescence (XRF). Results X-ray fluorescence was performed on a total of 60 samples from 30 patients. Of these 29 matched pairs (of cancer and normal liver distant from cancer from the same patient) were eligible for univariate analysis. Iron (0.00598 vs. 0.02306), copper (0.00541 vs. 0.00786) and zinc (0.01790 vs. 0.04873) were statistically significantly lower in the cancer tissue than the normal liver. Iron, copper, and zinc were lower in the cancer tissue than in the normal liver in 24/29 (82.8%), 23/29 (79.3%), and 28/29 (96.6%) of cases respectively. Multivariate analysis of the 60 samples revealed that zinc was the only trace element decreased in the cancer tissue after adjusting for the other elements. Zinc levels were not affected by any of the histopathological variables. Conclusion Iron, copper, and zinc are lower in colorectal liver metastases than normal liver. An investigation into the pathways underlying these differences may provide a new understanding of cancer development and possible novel therapeutic targets.     

Changes in the microbial community structure during thermophilic composting of manure as detected by the quinone profile method

Quinone profiles and physico-chemical properties were measured to characterize the microbial community structure during a 14-day thermophilic composting of cattle manure mixed with rice straw as a bulking agent. The change in total quinone content (TQ) and the divergence of quinone (DQ) indicated that the microbial biomass reached a peak followed by a decrease, whereas the microbial community diversity increased continuously during the composting process. The high mole fraction of ubiquinones in the raw materials, and at the beginning of the composting period suggested that fungi and/or Proteobacteria were present. The predominance of MK-7 from days 3 to 7 suggested that Bacillus spp. were the main microbial species. An increase in partially saturated and long-chain menaquinones during the latter composting period indicated that the proliferation of various species of Actinobacteria was occurring. The microbial community structure, as expressed by TQ and DQ, corresponded well to physico-chemical properties such as the C/N ratio, pH, O₂ consumption and compost mass reduction.     

Uptake of six heavy metals by oat as influenced by soil type and additions of cadmium,lead, zinc and copper

Summary The influence of heavy metal additions on availability and uptake of cadmium, lead, zinc, copper, manganese and iron by oat was studied. The experiments were carried out as pot experiments using sandy loam, sandy soil and organic soil. Selective extractants were used to remove metals held in different soil fractions.Lead and copper were preferently bound by organics and oxides, zinc by oxides and inorganics, and cadmium by inorganics and organics.Addition of cadmium to the soils resulted in higher cadmium concentrations in all plant parts but lower concentrations of lead, zinc, copper, manganese and iron, and the accumulation indexes of these metals were also lower when cadmium was added to the soil.Addition of cadmium plus lead, zinc and copper resulted in higher cadmium concentrations in leaves and straw of plants grown in sandy loam and sandy soil, but lower concentrations when plants were grown in organic soil as compared with the results when cadmium was added separately. The transfer of cadmium, lead, zinc and copper from soil to plant was greatest from sandy soil, and zinc and cadmium were more mobile in the plant than were lead and copper.Cadmium concentrations in leaves correlated significantly with CaCl₂ and CH₃COOH extractions in sandy loam and sandy soil and with CH₃COOH extractions in organic soil.Generally, the total metal uptake was lowest from organic soil.     

A method for controlling the activities of free metal,hydrogen, and phosphate ions in hydroponic solutions using ion exchange and chelating resins

Summary An ion exchange and chelating resin system was developed to buffer the activities of selected free cations and phosphate in hydroponic solutions at concentrations similar to those that occur naturally in soil solutions. Free-ion activities of Cd, Cu, Ni, Zn, Mn, H, Ca, Mg, and K were maintained by ion exchange and chelating resins in a controlled ionic strength system. Iron was controlled by EDDHA and chelating resin, and P by a cation-exchange resin containing adsorbed polynuclear hydroxyaluminum. This mixed-resin hydroponic system was used to establish a range of ionic Cd activities similar to that found in soil solutions of soils amended with sewage sludge. Activities of other nutrients were maintained at realistic soil-solution levels. A metal complexing agent (EDTA) was used to increase total metal concentration in the hydroponic solutions without significantly altering the ionic activities of the metals maintained in solution. This allowed differentiation of the effects of free ions and complexed metals on metal uptake. Concentrations of metal complexes in solution were controlled by the ion activities of the metals maintained and the concentrations and selectivities of the complexing agent. The mixed-resin system supplied sufficient nutrients for the growth of tomato plants (Lycopersicon esculentum, cv. Wisconsin-55) in hydroponic culture. Research supported by the College of Agricultural and Life Sciences, University of Wisonsin-Madison and by United States Environmental Protection Agency through Grant CR807270010.     

Response to acute nickel toxicity in rats as a function of sex

Summary The effects of different nickel chloride doses upon blood and plasma glucose and essential metal homeostasis were studied in male and female rats. A definite sex-dependent response to injections of nickel has been observed for both the increase in plasma and blood glucose levels and the time at which these levels peak. Males showed a fast recovery from the rise in glucose levels and were much less affected by changes in the other parameters studied. In females, an extended rise in glucose levels was observed. All these effects are clearly nickel dose-dependent. Plasma, liver and kidney copper levels rose significantly in females while only a small decrease was observed in male kidneys. Zinc levels rose in all organs studied but males recovered to basal levels after the study period, whereas females maintained maximum levels at the end of the same period. An increase in urinary excretion of iron was observed. The present results show that the sex differences to acute nickel toxicity can be a helpful way to study metal interaction and discriminate between specific toxicity due to nickel or that induced by the associated hyperglucagonemia.     

Differential pulse polarography: a method of directly measuring uptake of metal ions by live bacteria without separation of biomass and medium

Abstract The technique of differential pulse polarography is shown here for the first time to be applicable to monitoring directly the uptake of metal ions from solution by live bacteria in the chamber of the polarograph. The potential at which the polarographic current peak is observed is characteristic of the metal, whereas peak height is proportional to metal concentration. Adding solutions of Cd(II) or Zn(II) to a suspension of Pseudomonas cepacia in 50 mM Hepes buffer (pH 7.4) in the chamber gave polarographic peaks of lower amplitude than those observed when these metal solutions were added to buffer alone, due to metal binding or uptake by cells. Langmuir plots gave binding capacities of 0.13 and 0.20 mmol metal (Dd or Zn, respectively) per g (dry weight) biomass. Ni(II) uptake was biphasic. Metal uptake increased with pH. The value of polarography for rapid assessment of metal removal by cells and the ability to measure uptake from multi-metal solutions is demonstrated.     

Comparison of metallothionein concentrations and tissue distribution of trace metals in crabs (Pachygrapsus marmoratus) from a metal-rich estuary,in and out of the reproductive season

Crabs, Pachygrapsus marmoratus, were sampled in June 1997 and February 1998 from two sites (at the mouth and 25 km upstream) in the metal-rich Gironde estuary, France. Gills and hepatopancreas were analysed for metal (Cd, Cu, Zn) and metallothionein (MT) contents, in order to examine the influence of both biological and environmental factors on the physico-chemical forms of detoxified metal storage in the crabs. The concentrations of MT and both cytosolic and insoluble metals were not greatly different between males and females, and the influence of organ weights was also minimal. Intersite differences were observed, probably resulting from the gradient of salinity in the estuary, which interacts with both the chemical speciation and bioavailability of metals, and the general protein metabolism of the crabs. Seasonal changes were also important, probably in interaction with the moult and reproductive cycles. In February, concentrations of insoluble metals were generally higher than in June, in both organs, suggesting that essential metals, particularly Zn, are stored during winter then remobilised during the breeding season. The natural variability in the concentrations of MT often concealed any relationship with accumulated metal concentrations. Thus MT in crabs cannot be considered as a useful biomarker of metal pollution.     

Determination of relative bioavailability of zinc in a petit suisse cheese using weight gain and bone zinc content in rats as markers

The aim of the study was to determine the relative bioavailability of zinc gluconate stabilized with glycine in a Petit Suisse cheese from an infant dessert. Weight gain and bone zinc content were the nutritional responses evaluated for the diets of different zinc content: 2 ppm (basal) and 5, 10, and 30 ppm from zinc gluconate stabilized with glycine and zinc sulfate. Nonlinear regression analysis of the fitted curves for weight gain determined a relative zinc bioavailability of 100% for the Y _max ratio and 96% for Y _max/t _1/2 ratio for zinc gluconate stabilized with glycine (R ²=0.7996 for zinc sulfate and 0.8665 for zinc gluconate stabilized with glycine). The slope ratio analysis from linear regression of femur zinc determined a relative zinc bioavailability of 93% for zinc gluconate stabilized with glycine (R ²=0.8693 for zinc sulfate and 0.8307 for zinc gluconate stabilized with glycine). Zinc gluconate stabilized with glycine has similar bioavailability as zinc sulfate in a Petit Suisse cheese nutritional matrix, with the advantage that the stabilized compound does not modify the sensorial characteristics of the fortified cheese.     

Effects of a soil fulvic acid on the growth and nutrient content of cucumber (Cucumis sativus) plants

Summary Cucumber (Cucumis sativus) plants were grown in Hoagland solution to which 20 to 2000 ppm of a soil fulvic acid (FA) were added. The addition of 100 to 300 ppm of FA produced highly significant increases in the growth and development of above and below ground plant parts, in the uptake of nutrient elements (N, P, K, Ca, Mg, Cu, Fe and Zn), and in the formation of numbers of flowers per plant. Effects of adding 500 and more ppm of FA were less beneficial.     

The use of a white rot fungi (Pleurotus ostreatus) immobilized on Amberlite XAD-4 as a new biosorbent in trace metal determination

The present work proposes the use of Pleurotus ostreatus immobilized on Amberlite XAD-4 as new biosorbent in trace metal determination. The effects of experimental parameters, such as “pH and flow rate of sample solution, amount of solid phase, eluent type, and concentration” on the recovery of the metal ions were investigated. Maximum adsorption of Cr(III), Cd(II) and Cu(II) ions took place in the pH range 4-5. These metal ions can be desorbed with 1 M HCl (recovery 95-100%). 0.2 g adsorbent amount and 2.5 mL min⁻¹ flow rate was found to be optimum of all preconcentration experiments. The sorption capacity after 10 cycles of sorption and desorption does not vary more than 2.0%. The influences of the contaminant ions on the retentions of the analytes were also examined. The results showed that P. ostreatus immobilized on Amberlite XAD-4 can be considered as very promising material in trace metal determination.     

Use of aquatic macrophytes as a bioassay method to assess relative toxicity,uptake kinetics and accumulated forms of trace metals

Floating aquatic macrophytes such as the Lemnaceae have many attributes which commend their use in laboratory and field investigations to assess both the toxicity of substances and the quality of freshwater systems. As well as their more well known advantages of small size, relative structural simplicity, rapid growth and vegetative reproduction and genetically homogenous populations, they are also excellent accumulators of a number of metallic elements. This raises the possibility of the use of these aquatic macrophytes in water quality monitoring and also as laboratory bioassays for toxicity and uptake studies. Results are presented of a study of the comparative toxicity, uptake kinetics and accumulated forms of thallium and cadmium in the duckweed, Lemna minor and the role of this methodology in water quality monitoring and hazard evaluation are discussed.     

Generation and characterization of a novel kidney-specific manganese superoxide dismutase knockout mouse

Inactivation of manganese superoxide dismutase (MnSOD), a mitochondrial antioxidant, has been associated with renal disorders and often results in detrimental downstream events that are mechanistically not clear. Development of an animal model that exhibits kidney-specific deficiency of MnSOD would be extremely beneficial in exploring the downstream events that occur following MnSOD inactivation. Using Cre-Lox recombination technology, kidney-specific MnSOD deficient mice (both 100% and 50%) were generated that exhibited low expression of MnSOD in discrete renal cell types and reduced enzymatic activity within the kidney. These kidney-specific 100% KO mice possessed a normal life-span, although it was interesting that the mice were smaller. Consistent with the important role in scavenging superoxide radicals, the kidney-specific KO mice showed a significant increase in oxidative stress (tyrosine nitration) in a gene-dose dependent manner. In addition, loss of MnSOD resulted in mild renal damage (tubular dilation and cell swelling). Hence, this novel mouse model will aid in determining the specific role (local and/or systemic) governed by MnSOD within certain kidney cells. Moreover, these mice will serve as a powerful tool to explore molecular mechanisms that occur downstream of MnSOD inactivation in renal disorders or possibly in other pathologies that rely on normal renal function.