Uptake of silica nanoparticles: neurotoxicity and Alzheimer-like pathology in human SK-N-SH and mouse neuro2a neuroblastoma cells.

Growing concern has been raised over the potential adverse effects of engineered nanoparticles on human health due to their increasing use in commercial and medical applications. Silica nanoparticles (SiNPs) are one of the most widely used nanoparticles in industry and have been formulated for cellular and non-viral gene delivery in the central nerve system. However, the potential neurotoxicity of SiNPs remains largely unclear. In this study, we investigated the cellular uptake of SiNPs in human SK-N-SH and mouse neuro2a (N2a) neuroblastoma cells treated with 10.0 µg/ml of 15-nm SiNPs for 24 h by transmission electron microscopy. We found that SiNPs were mainly localized in the cytoplasm of the treated cells. The treatment of SiNPs at various concentrations impaired the morphology of SK-N-SH and N2a cells, characterized by increased number of round cells, diminishing of dendrite-like processes and decreased cell density. SiNPs significantly decreased the cell viability, induced cellular apoptosis, and elevated the levels of intracellular reactive oxygen species (ROS) in a dose-dependent manner in both cell lines. Additionally, increased deposit of intracellular ß-amyloid 1-42 (Aß(1-42)) and enhanced phosphorylation of tau at Ser262 and Ser396, two specific pathological hallmarks of Alzheimer's disease (AD), were observed in both cell lines with SiNPs treatment. Concomitantly, the expression of amyloid precursor protein (APP) was up-regulated, while amyloid-ß-degrading enzyme neprilysin was down-regulated in SiNP-treated cells. Finally, activity-dependent phosphorylation of glycogen syntheses kinase (GSK)-3ß at Ser9 (inactive form) was significantly decreased in SiNP-treated SK-N-SH cells. Taken together, these data demonstrated that exposure to SiNPs induced neurotoxicity and pathological signs of AD. The pre-Alzheimer-like pathology induced by SiNPs might result from the dys-regulated expression of APP/neprilysin and activation of GSK-3ß. This is the first study with direct evidence indicating that in addition to neurotoxicity induced by SiNPs, the application of SiNPs might increase the risk of developing AD.

[Comparison of the contents of mineral elements in the roots of four germplasms Bupleurum L. planted in different soils].

Contents of 21 elements, including of K, Ca, Mg, Na, Fe, Mn, Cu, Zn, Ni, Ti, Cr, Mo, V, Zr, Co, Se, Sn, Cs, Cd, Hg, and Pb, in the roots of four germplasms Bupleurum L. planted in the soils from seven regions, were analyzed by ICP-MS/ICP-AES. The results showed that the contents of K, Ca, Mg and Na are mainly ascribed to the effect of germplasms, and the contents of Fe, Cu, Ni, Ti, Cr, V, Zr, Se, Sn, Cs, Cd, Hg and Pb are mainly ascribed to the effect of soils considering the integrated effects of germplasms and soils. Generally, element contents in the root of G-GS were higher and that in the root of G-ZC were lower in the four germplasms of Bupleurum L. Element contents in the root of Bupleurum L. planted in S-HR were higher, while that planted in SYQS were lower as a whole among these soils from seven regions. The difference in the element contents has an important effect on the research into the contents of officinal ingredients and their curative effect in the roots of four original Bupleurum L. germplasms planted in the soils from seven regions. And this study also provides an important scientific foundation for the choices of germplasms and soils in the cultivation of high-yield and high-quality Bupleurum L.

[Comparison of the contents of trace elements in the roots of four original danshen (Salvia miltiorrhiza bunge)].

The root and rhizome of danshen (salvia miltiorrhiza bunge), one of the earliest and also the most commonly used herbal drugs in practice of traditional Chinese medicines, has been confirmed effective for coronary heart disease, including angina pectoris, coronary artery spasm, myocardial infarction, etc., based on modern investigations. And some trace elements were found related to these diseases. Therefore it was important to research trace elements and their contents in the root for studying pharmic mechanism of danshen. The contents of 22 trace elements, including Ca, Mg, Fe, Zn, V, Mn, Cr, Cu, Rb, Sr, Ba, Pb, B, As, Se, Li, Co, Ni, Mo, Cd, Sn and Hg, in the roots of danshen germplasm, originating from four planting regions and grew in the same place, were analyzed by ICP-MS/ICP-AES. The results showed that the contents of trace elements in the root of Shandong white flower danshen were higher as a whole. And the contents of Ca, Fe, Zn, Mn, Cu, Ba, Li, Co, Ni and Hg in the root of Shandong white flower danshen were the highest among the four kinds of original danshen, in which the contents of Zn, Mn, Cu, Ni and Hg were significantly higher than those in the three kinds of original violet flower danshen. The contents of Rb and Mo in the root of Shanxishangluo violet flower danshen were the smallest and that of Ni was the highest among the three kinds of original violet flower danshen. Compared with the difference between white flower danshen and violet flower danshen, the difference of rest nineteen kinds of trace elements contents among the three kinds of original violet flower danshen was smaller. The difference in the contents of trace elements has an important effect on the research into the contents of officinal ingredients and their curative effect of the roots of four kinds of original danshen germplasm.

Nitrogen deposition and its contribution to nutrient inputs to intensively managed agricultural ecosystems.

Interest in nitrogen inputs via atmospheric deposition to agricultural ecosystems has increased recently, especially on the North China Plain because of extremely intensive agricultural systems and rapid urbanization in this region. Nitrogen deposition may make a significant contribution to crop N requirements but may also impose a considerable nutrient burden on the environment in general. We quantified total N deposition at two locations, Dongbeiwang near Beijing and Quzhou in Hebei province, over a two-year period from 2005 to 2007 using an 15N tracer method, the integrated total N input (ITNI) system. Total airborne N inputs to a maize wheat rotation system at both locations ranged from 99 to 117 kg N x ha(-1) x yr(-1), with higher N deposition during the maize season (57-66 kg N/ha) than the wheat season (42-51 kg N/ha). Plant available N from deposition for maize and wheat was about 52 kg N x ha(-1) x yr(-1), accounting for 50% of the total N deposition or 31% of total N uptake by the two crop species. In addition, a correction factor was derived for the maize season to adjust values obtained from small pots (0.057 m2) compared with field trays (0.98 m2) because of higher plant density in the pots. The results indicate that atmospheric N deposition is a very important N input and must be taken into account when calculating nutrient budgets in very intensively managed agricultural ecosystems.

[Formation of iron plaque on root surface and its effect on plant nutrition and ecological environment].

This paper illustrated the conditions of iron plaque formation on root surface, the morphology, mineralogical composition and deposition site of the plaque, and its function as a Fe reservoir in supplying Fe nutrient and affecting the uptake of other nutrients such as phosphorus and zinc. The environmental and ecological role of the plaque in inhibiting the uptake and translocation of heavy metals such as Cu, Ni, Cd and As through absorption or co-precipitation was called external tolerance mechanism, while its competition with heavy metals for metabolically sensitive sites in plants was called internal tolerance mechanisms. These two mechanisms help plant survive in high acidic and low carbon environment.