Development and validation of abiotic ligand model for nickel toxicity to wheat(Triticum aestivum)

A terrestrial biotic ligand model（t-BLM） was developed to predict nickel toxicity to wheat（Triticum aestivum） root elongation in hydroponic solutions. The competitive effects of five major cations（Ca^（2＋）, Mg^（2＋）, Na~＋, K~＋and H~＋） on Ni toxicity were investigated and Mg^（2＋）was found to be a strong competitor, while H＋showed less competing effect. Besides free Ni^（2＋）,the toxicity induced by the species NiHCO_3~＋ was non-neglect able at pH 〉 7 because NiHCO_3~＋ occupied a significant fraction of total Ni under such condition. Thus, a t-BLM including Ni^（2＋）, NiHCO_3~＋, Mg^（2＋）, and H＋could successfully predict the nickel toxicity to wheat root elongation and it performed better prediction than the conventional free ion activity model.In addition, the model was examined with two sets of independent experiments, which contained multiple cations and low-molecular-weight organic acids to mimic the rhizosphere condition. The developed t-BLM well predicted nickel toxicity in both experiments since it can account in both complexation and competition effects, suggesting its potential to be used in a complicated matrix like soil solution. This study provides direct evidence that the t-BLM is a reliable method for the risk assessment of nickel in terrestrial system.

Comparison of phytotoxicity of copper and nickel in soils with different Chinese plant species

Ecological risk assessment of metals in soils is important to develop the critical loads of metals in soils. Phytotoxicity is one of the endpoints for ecological risk assessment of soils contaminated with metals. The sensitivity of eight Chinese plant species（bok choy, mustard, tomato, green chilli, paddy rice, barley, spinach and celery） to copper（Cu） and nickel（Ni） toxicity in two Chinese soils was investigated to assess their potential use for ecological risk assessment in the region. The results showed that bok choy and mustard were the two most sensitive species to Cu and Ni toxicities. Assessment of metal accumulation by the plants demonstrated that bok choy shoot had the highest bioconcentration factor（BCF, the ratio of metal concentration in plant shoots to metal concentration in soil）. Given the importance of bok choy to agricultural production in Asia, it is therefore important that these sensitive plant species are included in species sensitivity distributions for ecological risk assessment of Cu and Ni in soils.

Renal Toxicity of Nickel,Sodium Lauryl Sulphate and Their Combination after Dermal Application in Guinea Pigs

The guinea pigs were dermally exposed to nickel (Ni), sodium lauryl sulphate (SLS) and in their combination for 7 and 14 days. The exposure to Ni and SLS produced changes in enzymes and lipid peroxidation in kidney. The exposure to Ni or SLS depicted slight changes while combined exposure to Ni plus SLS exhibited more degenerative changes in kidney. The result of the study suggests that industrial workers and/or populations exposed simultaneously to Ni and SLS produces more damage to kidney.

Expression of Genes Associated with Nickel Resistance in White Spruce (<i>Picea glauca</i>) under Nickel Stress: Analysis of AT2G16800 and <i>NRAMP</i>Genes

Heavy metals such nickel (Ni) can cause toxicity by 1) displacing essential components in the biomolecules, 2) blocking the functional group of molecules, or 3) modifying enzymes, proteins, the plasma membrane, and membrane transporters. The main objective of the present study was to investigate the effect of nickel (Ni) on gene expression of nitrate on gene expression with a focus on the genes coding for the high affinity Ni transporter family protein AT2G16800, and natural resistance-associated macrophage protein (NRAMP). Ni toxicity was assessed by treating seedlings with an aqueous solution of nickel nitrate salt [Ni(NO3)2] at the concentrations of 150 mg, 800 mg, and 1600 mg of nickel per 1 kg of dry soil. RT-qPCR was used to measure the expression of AT2G16800, and NRAMP genes in samples treated with nickel nitrates and controls. The results revealed that P. glauca is resistant to Ni based on lack of plant damage at all nickel concentrations. Ni has no effect on the expression of the AT2G16800 gene in needles or roots. However, it induced an upregulation of the NRAMP genes in roots at all the doses tested (150 mg/kg, 800 mg/kg, and 1600 mg/kg). On the other hand, Ni has no effect on the expression of the NRAMP gene in needle but the lowest dose of potassium (150 mg/kg) upregulated this gene in needle tissues.