[Effects of elevated ozone concentrations on enzyme activities and organic acids content in wheat rhizospheric soil.] / O3æµ“åº¦å‡é«˜å¯¹å°éº¦æ ¹é™ åœŸå£¤é ¶æ´»æ€§å’Œæœ‰æœºé ¸å«é‡çš„å½±å“.

The elevated concentration of tropospheric ozone (O3) is an important global climate change driver, with adverse impacts on soil ecological environment and crop growth. In this study, a pot experiment was carried out in an open top chamber (OTC), to investigate the effects of elevated ozone concentration on soil enzyme activities (catalase, polyphenol oxidase, dehydrogenase and invertase), organic acids contents (oxalic acid, citric acid and malic acid) at different growth stages (tillering, jointing, heading and ripening stages) of wheat, and combined with the rhizospheric soil physicochemical properties and plant root characteristics to analyze the underlying reasons. The results showed that, elevated ozone concentration increased soil catalase, polyphenol oxidase, dehydrogenase and invertase activities at wheat ripening period to different degrees, with the effects on the activities of catalase and polyphenol oxidase being statistically significant. At the heading stage, activities of dehydrogenase and invertase were significantly increased by up to 76.7%. At the ripening stage, elevated ozone concentration significantly increased the content of citric acid and malic acid and redox potential (Eh) in rhizospheric soil, but reduced soil pH, electrical conductivity, total carbon and nitrogen. For root characteristics, elevated ozone concentrations significantly reduced the wheat root biomass, total root length and root surface area but increased the average root diameter.

Endothelial progenitor cells from human fetal aorta cure diabetic foot in a rat model.

OBJECTIVE: Recent evidence has suggested that circulating endothelial progenitor cells (EPCs) can repair the arterial endothelium during vascular injury. However, a reliable source of human EPCs is needed for therapeutic applications. In this study, we isolated human fetal aorta (HFA)-derived EPCs and analyzed the capacity of EPCs to differentiate into endothelial cells. In addition, because microvascular dysfunction is considered to be the major cause of diabetic foot (DF), we investigated whether transplantation of HFA-derived EPCs could treat DF in a rat model. METHODS: EPCs were isolated from clinically aborted fetal aorta. RT-PCR, fluorescence-activated cell sorting, immunofluorescence, and an enzyme-linked immunosorbent assay were used to examine the expressions of CD133, CD34, CD31, Vascular Endothelial Growth Factor Receptor 2 (VEGFR2), von Willebrand Factor (vWF), and Endothelial Leukocyte Adhesion Molecule-1 (ELAM-1). Morphology and Dil-uptake were used to assess function of the EPCs. We then established a DF model by injecting microcarriers into the hind-limb arteries of Goto-Kakizaki rats and then transplanting the cultured EPCs into the ischemic hind limbs. Thermal infrared imaging, oxygen saturation apparatus, and laser Doppler perfusion imaging were used to monitor the progression of the disease. Immunohistochemistry was performed to examine the microvascular tissue formed by HFA-derived EPCs. RESULTS: We found that CD133, CD34, and VEGFR2 were expressed by HFA-derived EPCs. After VEGF induction, CD133 expression was significantly decreased, but expression levels of vWF and ELAM-1 were markedly increased. Furthermore, tube formation and Dil-uptake were improved after VEGF induction. These observations suggest that EPCs could differentiate into endothelial cells. In the DF model, temperature, blood flow, and oxygen saturation were reduced but recovered to a nearly normal level following injection of the EPCs in the hind limb. Ischemic symptoms also improved. Injected EPCs were preferentially and durably engrafted into the blood vessels. In addition, anti-human CD31+-AMA+-vWF+ microvasculars were detected after transplantation of EPCs. CONCLUSION: Early fetal aorta-derived EPCs possess strong self-renewal ability and can differentiate into endothelial cells. We demonstrated for the first time that transplanting HFA-derived EPCs could ameliorate DF prognosis in a rat model. These findings suggest that the transplantation of HFA-derived EPCs could serve as an innovative therapeutic strategy for managing DF.

[Nitrogen and phosphorus input from wet deposition in Taihu Lake region: a case study in Changshu Agro-ecological Experimental Station].

From June 2003 to May 2004, the precipitation at Changshu Agro-ecological Station (31 degrees 32'45" N, 120 degrees 41'57" E) of Chinese Academy of Sciences was collected to monitor its particle- and dissolved nitrogen and phosphorus concentrations, with the seasonal variation of nitrogen and phosphorus in wet deposition in Taihu Lake region investigated. The nitrogen input from wet deposition had an obvious seasonal variation, being higher in summer and spring and lower in autumn and winter. The ratios of dissolved nitrogen (DN) and particle nitrogen (PN) to total nitrogen (TN) in wet deposition were 88.2% and 11.8%, and those of dissolved phosphorus (DP) and particle phosphorus (PP) to total phosphorus (TP) were 53.3% and 46.7%, respectively. The amounts of nitrogen and phosphorus deposited into Taihu Lake region by light and medium precipitation were higher than those by heavy precipitation. The annual input of TN and TP from wet deposition was 30.2 kg x hm(-2) and 1.1 kg x hm(-2), respectively, and the DN concentration in all precipitation events as well as the DP concentration in 92.5% of precipitation events was higher than the thresholds of inland water eutrophication.