[Effects of potassium on nitrogen translocation and distribution and nitrogen metabolism enzyme activities of sweet potato.] / æ–½é’¾å¯¹ç”˜è–¯æ°®ç´ è½¬ç§»åˆ†é åŠæ°®ä»£è°¢é ¶æ´»æ€§çš„å½±å“.

A pot experiment with 15N tracing techniques was designed to study the effect of potassium application on nitrogen transfer, photosynthetic characteristics and nitrogen metabolism enzyme activities in two different growth stages of sweet potato. Results indicated that potassium application significantly increased the shoot 15N distribution rate. Compared with control, the 15N transfer rate of K3 treatment increased by 76.2% and the total accumulation of 15N increased by 92.1% in tuber formation period. Different with tuber formation period, shoot 15N distribution rate decreased from 33.7% to 24.4%, but the root 15N distribution rate increased from 5.8% to 17% with the increase of K application in tuber rapid growth stage. Especially, root 15N accumulation of K3 treatment was 3 times of the CK. During the two growth stages, nitrate reductase, glutamate dehydrogenase, glutamine synthetase, glutamate synthase and net photosynthetic rate all increased with the increase of K application. Stepwise regression analysis showed that nitrogen metabolism enzyme activities (nitrate reductase, glutamate dehydrogenase, glutamine synthetase, glutamate synthase) and Pn were the main factors to affect the 15N transfer and distribution of sweet potato (R1=0.965,R2=0.942). Path analysis showed that nitrate reductase and glutamate dehydrogenase activities were the key factors to influence 15N distribution to the shoot in tuber formation period, while glutamate dehydrogenase, glutamate synthase activities were the key factors to influence 15N distribution to the tuber in tuber rapid growth stage.

[Phthalic acid esters (PAEs) pollution in farmland soils: a review].

The environmental pollution and food safety problems caused by phthalic acid esters (PAEs) have been attracted 'extensive attention around the world. As a large PAEs producer and consumer, China is facing severe PAEs environmental pollution problems. This paper reviewed the present pollution status of six PAEs classified by the U.S. Environmental Protection Agency as the priority pollutants in China farmland soils, analyzed the sources of these six PAEs in this country, and discussed the absorption and accumulation characteristics of the PAEs in different crops as well as the bio-toxic effects of PAEs pollutants. The PAEs concentrations in China farmland soils are significantly higher those in the farmland soils of the United States and European countries. The main sources of PAEs in China farmland soils are atmospheric deposition, agricultural films, sewage sludge application, and wastewater irrigation. There exist significant differences in the characteristics of PAEs absorption, accumulation, and distribution among different crops. PAEs not only have negative effects on soil quality, crop growth, and crop physiological and biochemical properties, but also possess bio-accumulative characteristics. The weaknesses in current researches were pointed out, and the suggestions for the further researches were given, e. g., to expand the scope of PAEs pollution survey, to explore the toxic mechanisms of PAEs on crops, and to develop the techniques for in situ remediation of PAEs-polluted soils.

[Distribution characteristics of phthalic acid esters in soils and peanut kernels in main peanut producing areas of Shandong Province, China].

Surface soil (0-20 cm) and peanut kernel samples were collected in four main peanut producing areas of Shandong Province, and the contents of six PAEs chemicals that classified by the U. S. Environmental Protection Agency as priority pollutants were determined by gas chromatography (GC). The results indicated that the total concentration of six PAEs (sigma PAEs) ranged from 0.34 to 2.81 mg x kg(-1), and the mean was 1.22 mg x kg(-1). In four different areas, the order of sigmaPAEs concentration in soil was hilly area of middle southern Shandong > western plain of Shandong > Jiaodong Peninsula > northern plain of Shandong. The concentration of DBP in four main peanut producing areas of Shandong Province seriously exceeded the control limit in USA. The content of PAEs ranged from 0.17 to 0.66 mg x kg(-1) in peanut kernels, with the average value 0.34 mg x kg(-1) which was less than the suggested targets in USA and Europe and of low health risk. DEHP and DBP were the main components of PAEs both in soils and peanut kernels, with higher percentage content and detection rate. The sigma PAEs contents in soils or peanut kernels under plastic mulching were significantly higher than that of open field cultivation pattern. The PAEs concentrations in peanut kernels and soils had significant correlation, with the Pearson coefficient 0. 786 (sigma PAEs), 0.747 (DBP) and 0.511 (DEHP), respectively.

[Protective effects of total epimedium flavonoids against QA-induced toxicity in SH-SY5Y cells].

OBJECTIVE: To investigate the protective effects and its mechanisms of total epimedium flavonoids (TEF) against Quindinince acid (QA)-induced toxicity in SH-SY5Y cells. METHODS: The MT assay was used to detect the toxicity of QA and the cell viability of pretreatment of TEF and co-incubation with QA in SH-SY5Y cells; Cell apoptosis was observed by Hochest33258 staining; SOD and GSH-Px activities as well as MDA content were measured by colorimetric method; The mitochondrial membrane potential (delta psi m) and intracellular free calcium concentration ([Ca2+]i) were monitored by FCM. RESULTS: TEF increased the cell viability of SH-SY5Y cells, reduced apoptosis cells significantly, improved SOD and GSH-Px activities, decreased MDA content, increased the mitochondrial membrane potential and reduced intracellular free calcium concentration( [Ca2+]i ). CONCLUSION: TEF has significant protective effects against QA-induced toxicity in SH-SY5Y cells,the action mechanism may be associated with resisting oxidative stress, decreasing the [Ca2]i and up-regulating delta psi m.