ABSTRACT
Background@#Nickel-induced allergic contact dermatitis (Ni-ACD) is a global health problem. More detailed knowledge on the skin uptake of haptens is required. This study aimed to investigate the penetration process and distribution of nickel in skin tissues with late phase and early phase of Ni-ACD to understand the mechanisms of metal allergy.@*Methods@#Forty Hartley guinea pigs were divided into four groups according to the NiSO4 sensitizing concentration and the NiSO4 challenged concentration: the 5% NiSO4-group, 5% to 10% (sensitization-challenge; late phase group); 10% NiSO4-group, 10% to 10% (sensitization-challenge; early-phase group); and the positive and negative controls. Pathological biopsies were performed on each group. The depth profile of nickel element concentration in the skin of guinea pigs was detected by synchrotron radiation micro X-ray fluorescence spectroscopy (SR-μ-XRF) and micro X-ray absorption near-edge spectroscopy (μ-XANES).@*Results@#In each section, the nickel element concentration in both the 5% NiSO4-group and 10% NiSO4-group was significantly higher than that in the negative control group. In the upper 300-μm section of skin for the early phase group, the nickel element concentration was significantly higher than that in the lower section of skin. In deeper sections (<200 μm) of skin, the concentration of nickel in the early phase group was approximately equal to that in the late phase group. The curve of the late phase group was flat, which means that the nickel element concentration was distributed uniformly by SR-μ-XRF. According to the XANES data for the 10% NiSO4 metal salt solution, structural changes occurred in the skin model sample, indicating that nickel was not present in the Ni2+ aqueous ionic state but in the nickel-binding protein.@*Conclusions@#This study showed that the distribution of the nickel element concentration in ACD skin tissue was different between the early phase and late phase groups. The nickel element was not present in the Ni2+ aqueous ionic state but bound with certain proteins to form a complex in the stratum corneum in ACD model tissue.
ABSTRACT
To reveal the mechanism of Cu enrichment of alfalfa, in-situ micro-X-ray fluorescence spectrometry (μ-XRF) and fractional extraction were used to explore in-situ Cu distribution information in alfalfa seedlings and different combination forms of Cu in organs.The results showed that alfalfa roots were enriched with Cu up to 12.06 mg/g, which was 8 times of stem and 4.9 times of leaves.The in-situ μ-XRF result showed that the root of alfalfa was the main site of enrichment of Cu, and there was a barrier of Cu at the rhizome junction to alleviate the toxic effect of excess Cu on the shoots.Excess Cu (more than 50 μmol/L) also inhibited the uptake of Zn and Ca in alfalfa, enhanced the uptake of Fe in alfalfa, but had no obvious effect on the uptake of K and Mn.Plant fractional extraction showed that the Cu in root cells was mainly fixed in the form of insoluble residues (41%) and cell wall chelate (20%), while in the stem, Cu existed as four forms including hydrophobic protein binding, cell wall binding state, residual state and water-soluble state, which further reduce the excess transport of Cu to the leaves.In the leaves, excess Cu in the leaf cells was mainly in the vacuole and insoluble residue to achieve tolerance and detoxification to Cu.
ABSTRACT
Moss has high tolerance and accumulating capacity to heavy metal.In this study, the distribution of heavy metal elements in moss sampled from lead-zinc mine was analyzed by X-ray fluorescence spectrometry.The speciation of lead was analyzed by X-ray absorption near-edge spectroscopy.Research showed that the contents of Pb, Zn, Cd and As in the moss of the mining area were extremely high, and their maximum concentration were 1.06 mg/g , 1.23 mg/g, 30.5 μg/g, 13.2 μg/g, respectively.Besides, the shoots especially the new tissue of the moss were the major sites for accumulation and storage of heavy metals.The micro-distribution characteristics varied among Hypnum plumaeforme and Brachytheciumprocumbens, indicating the difference of different species of moss in absorption pathway, accumulation and tolerance mechanisms for heavy metal.Linear combination fitting results indicated that the main lead speciation in moss was lead phosphate (78%) and lead oxide (22%), which suggested that the precipitation of lead phosphate might be the main mechanism of tolerance for moss.