Manganese (Mn) is an essential micronutrient for plants, but is toxic when present in excess. The rice plant (Oryza sativa L.) accumulates high concentrations of Mn in the aerial parts; however, the molecular basis for Mn tolerance is poorly understood. In the present study, genes encoding Mn tolerance were screened for by expressing cDNAs of genes from rice shoots in Saccharomyces cerevisiae. A gene encoding a cation diffusion facilitator (CDF) family member, OsMTP8.1, was isolated, and its expression was found to enhance Mn accumulation and tolerance in S. cerevisiae. In plants, OsMTP8.1 and its transcript were mainly detected in shoots. High or low supply of Mn moderately induced an increase or decrease in the accumulation of OsMTP8.1, respectively. OsMTP8.1 was detected in all cells of leaf blades through immunohistochemistry. OsMTP8.1 fused to green fluorescent protein was localized to the tonoplast. Disruption of OsMTP8.1 resulted in decreased chlorophyll levels, growth inhibition in the presence of high concentrations of Mn, and decreased accumulation of Mn in shoots and roots. However, there was no difference in the accumulation of other metals, including Zn, Cu, Fe, Mg, Ca, and K. These results suggest that OsMTP8.1 is an Mn-specific transporter that sequesters Mn into vacuoles in rice and is required for Mn tolerance in shoots.
The influence of previous irrigation of sewage water from industry and daily life on the concentrations and chemical forms of heavy metals in soils was examined in Xijia Village, Pudong District, Shanghai, China. Soil samples were taken from three regions in the upland fields that varied in distance from the abandoned open canal. To understand the background levels of heavy metals in the agricultural soils in Pudong District, soils under different land use (upland fields, greenhouses and orchards) were sampled as references from four localities with no history of sewage water irrigation. Analyses of total amounts of Cr, Mn, Ni, Cu, Zn, As, Pb, Cd and Hg indicated that the amounts in the soils from the sewage irrigated field were markedly higher than the background levels. In particular, the total amounts of Cd and Zn in the soil at distances of 2 m and 10 m from the canal exceeded the permissible value set by the Chinese Environmental Quality Standard (GB 15618–1995). Although the contamination showed a trend of decreasing with increasing distance from the canal, the total amount of Cd was still higher than the permissible value 20 m from the canal. The chemical forms of Zn and Cd in the soils taken from Xijia Village and the reference upland soils were then evaluated using a sequential extraction method. In the case of the soils 2 m and 10 m from the canal, the highest amounts of Zn and Cd were found to indicate an occlusion in Fe oxides and retention by the clay exchange sites of the soils. Based on these results, it was recommended not to use these sewage irrigated fields in Xijia Village for agricultural purposes unless the necessary remediation measures were taken to lower the heavy metal concentrations to safe levels.
Characterization of the physico-chemical properties of the soils collected from Chongming Island in Shanghai, China, which is the largest alluvial island with a total area of about 1,070 km 2 in the world, has been conducted in order to investigate the current status of agricultural soils, with special reference to the effect of alluvial deposits on the development and utilization of the soils. The experimental results indicated that the soils from Qianjin Farm (QJ) and Dongfeng Farm (DF) on this Island were markedly influenced by the marine deposits and the saline groundwater and showed higher Na+ and CI-contents, whereas the soils from Xinhai Farm (XH), Luhua Town (LH), and Jiangkou Town (JK) were significantly affected by the fluvial deposits and showed higher CO a 2 -, HCO a -, and S042-contents. The basic cations in the topsoils had been evidently washed out, and hence their contents had decreased to a lower level in the soils (DF, XH, and LH) under rice cultivation for more than 10 years. A larger amount of organic matter and other available nutrients accumulated in the paddy soils (DF, XH, and LH) than in the upland soils (QJ and JK). The groundwater under the sampling sites showed a higher salinity, which contributed considerably to the salinization of the coastal soils. The soils from the upland fields (QJ and JK) showed a lower salt content in the subsoils than in the topsoils, in contrast to the paddy soils. The results of this experiment also indicated that the fluvial deposits tended to contribute to the formation of a sandier soil texture than the marine deposits.
Populations of Athyrium yokoscense, a fern that hyperaccumulates Zn and Cd, have often been found at abandoned mining sites in Japan, and are often accompanied by another Zn and Cd hyperaccumulating plant, Arabis flagellosa. We compared the Zn and Cd uptake characteristics of At. yokoscense and Ar. flagellosa and examined the influences of community development on Zn and Cd uptake by each plant. A soil culture experiment was conducted using a rhizobox system with seven compartments, each filled with a metalliferous soil taken from Ikuno‐cho, Hyogo Prefecture, Japan. The treatments consisted of the following three planting schemes: two plants of At. yokoscense (AY), two plants of Ar. flagellosa (AF) and a mixed planting of two plants of each species (AY+AF). After 3 months of cultivation, the Zn and Cd concentrations in the shoots were approximately 4.0 and 0.9 g kg−1 for At. yokoscense in the AY treatment and 24 and 0.3 g kg−1 for Ar. flagellosa in the AF treatment, respectively. These results indicated that Ar. flagellosa was more efficient at accumulating Zn in the shoots than At. yokoscense. In the AY+AF treatment, the amounts of water‐soluble Zn and Cd in the soil of the central compartments were significantly higher than those in the AY and AF treatments. Despite this, the Zn and Cd concentrations in the shoots of Ar. flagellosa in the AY+AF treatment were not significantly different from those in the AF treatment. The Cd content in the shoots of At. yokoscense was higher in the AY+AF treatment than in the AY treatment, owing to a growth enhancement in the AY+AF treatment. Consistent with the results for the AY and AF treatments, Ar. flagellosa accumulated higher shoot concentrations of Zn than At. yokoscense and At. yokoscense accumulated higher concentrations of Cd than Ar. flagellosa in the AY+AF treatment. These results suggested that the levels of Zn and Cd accumulated by these two plants were not largely affected by their community development, and implied that communities of these plants do not develop as a result of mutual effects on metal uptake.
Aims To investigate a new method of left atrial appendage occlusion without fluoroscopy. Methods and Results We performed left atrial appendage occlusion for 14 patients with atrial fibrillation in our hospital. All of the surgeries were completed in a general surgery setting, avoiding fluoroscopy, and in each case, the entire procedure was guided by transesophageal echocardiography (TEE). All of the surgeries were performed through the femoral vein pathway. All operations went smoothly with no serious complications. Postoperative TEE indicated that each device was in a good position, and there was no residual shunt around any of the devices. Conclusions TEE-guided left atrial appendage occlusion is safe and reliable, simplifies the procedure, protects doctors and patients from radiation, and is gradually becoming the mainstream operation for left atrial appendage occlusion. This trial is registered with ChiCTR1800018387.
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