Ammonia volatilization losses, nitrogen utilization efficiency, and rice yields in response to urea application to a rice field were investigated in Wangzhuang Town, Changshu City, Jiangsu Province, China. The N ferti...Ammonia volatilization losses, nitrogen utilization efficiency, and rice yields in response to urea application to a rice field were investigated in Wangzhuang Town, Changshu City, Jiangsu Province, China. The N fertilizer treatments, applied in triplicate, were 0 （control）, 100, 200, 300, or 350 kg N ha^-1. After urea was applied to the surface water, a continuous airflow enclosure method was used to measure ammonia volatilization in the paddy field. Total N losses through ammonia volatilization generally increased with the N application rate, and the two higher N application rates （300 and 350 kg N ha^-1） showed a higher ratio of N lost through ammonia volatilization to applied N. Total ammonia loss by ammonia volatilization during the entire rice growth stage ranged from 9.0% to 16.7% of the applied N. Increasing the application rate generally decreased the ratio of N in the seed to N in the plant. For all N treatments, the nitrogen fertilizer utilization efficiency ranged from 30.9% to 45.9%. Surplus N with the highest N rate resulted in lodging of rice plants, a decreased rate of nitrogen fertilizer utilization, and reduced rice yields. Calculated from this experiment, the most economical N fertilizer application rate was 227 kg ha^-1 for the type of paddy soil in the Taihu Lake region. However, recommending an appropriate N fertilizer application rate such that the plant growth is enhanced and ammonia loss is reduced could improve the N utilization efficiency of rice.展开更多
目的:探讨窄谱中波紫外线(narrow-band ultraviolet B,NB-UVB)通过促进维生素D(vitamin D,VD)代谢缓解咪喹莫特(imiquimod,IMQ)诱导银屑病样小鼠皮炎的效应机制。方法:C57BL/6小鼠背部去毛外涂IMQ乳膏进行银屑病样皮炎的造模,检测小鼠...目的:探讨窄谱中波紫外线(narrow-band ultraviolet B,NB-UVB)通过促进维生素D(vitamin D,VD)代谢缓解咪喹莫特(imiquimod,IMQ)诱导银屑病样小鼠皮炎的效应机制。方法:C57BL/6小鼠背部去毛外涂IMQ乳膏进行银屑病样皮炎的造模,检测小鼠血清中VD代谢产物25(OH)D_(3)和1,25(OH)_(2)D_(3)的含量,以及皮损中VD受体(vitamin D receptor,VDR)mRNA表达;确定NB-UVB照射小鼠的辐照能量后,进行造模联合NB-UVB照射,观察小鼠皮损,检测血清中25(OH)D_(3)和1,25(OH)_(2)D_(3)的含量、皮损中VDR和炎症因子[白细胞介素(interleukin,IL)-17A、IL-23、肿瘤坏死因子(tumor necrosis factor,TNF)-α、IL-1β]的mRNA表达及蛋白含量及CD_(3)^(+)CD4^(+)IL-17A^(+)T细胞比例。使用特异性抑制剂Dafadine-A阻断小鼠VD代谢关键酶细胞色素P450家族27亚家族A成员1(cytochrome P450 family 27 subfamily A member 1,CYP27A1)活性后,再进行造模和NB-UVB照射,观察皮损,检测皮损中CD_(3)^(+)CD4^(+)IL-17A^(+)T细胞比例、炎症因子表达情况、VDR mRNA表达情况和血清中25(OH)D_(3)、1,25(OH)_(2)D_(3)的含量。结果:银屑病样小鼠模型血清中25(OH)D_(3)、1,25(OH)_(2)D_(3)含量和皮损中VDR的mRNA表达均显著降低。NB-UVB照射银屑病样小鼠模型后,相比模型组,小鼠血清中25(OH)D_(3)、1,25(OH)_(2)D_(3)含量和皮损中VDR的mRNA表达上调,皮损中炎症因子IL-17A、IL-23、TNF-α、IL-1β的表达及含量均下调、CD_(3)^(+)CD4^(+)IL-17A^(+)T细胞比例也显著下降。使用Dafadine-A预处理小鼠后进行造模联合NB-UVB照射,相比IMQ联合NB-UVB照射组,血清中25(OH)D_(3)、1,25(OH)_(2)D_(3)含量和皮损中VDR的mRNA表达均显著降低,皮损中CD_(3)^(+)CD4^(+)IL-17A^(+)T细胞比例和炎症因子IL-17A、IL-23、TNF-α、IL-1β的含量均显著升高。结论:NB-UVB照射通过促进VD代谢缓解银屑病样小鼠皮肤炎症。特异性阻断VD代谢关键酶CYP27A1活性后,NB-UVB照射缓解银屑病样小鼠皮损及炎症反应的效应显著减弱。展开更多
基金Project supported by the Knowledge Innovation Program of Chinese Academy of Sciences (No.KZCX2-413-3)National Natural Science Foundation of China (No.30390080)National Basic Research Program of China (No.2005CB121108)
文摘Ammonia volatilization losses, nitrogen utilization efficiency, and rice yields in response to urea application to a rice field were investigated in Wangzhuang Town, Changshu City, Jiangsu Province, China. The N fertilizer treatments, applied in triplicate, were 0 （control）, 100, 200, 300, or 350 kg N ha^-1. After urea was applied to the surface water, a continuous airflow enclosure method was used to measure ammonia volatilization in the paddy field. Total N losses through ammonia volatilization generally increased with the N application rate, and the two higher N application rates （300 and 350 kg N ha^-1） showed a higher ratio of N lost through ammonia volatilization to applied N. Total ammonia loss by ammonia volatilization during the entire rice growth stage ranged from 9.0% to 16.7% of the applied N. Increasing the application rate generally decreased the ratio of N in the seed to N in the plant. For all N treatments, the nitrogen fertilizer utilization efficiency ranged from 30.9% to 45.9%. Surplus N with the highest N rate resulted in lodging of rice plants, a decreased rate of nitrogen fertilizer utilization, and reduced rice yields. Calculated from this experiment, the most economical N fertilizer application rate was 227 kg ha^-1 for the type of paddy soil in the Taihu Lake region. However, recommending an appropriate N fertilizer application rate such that the plant growth is enhanced and ammonia loss is reduced could improve the N utilization efficiency of rice.
文摘目的:探讨窄谱中波紫外线(narrow-band ultraviolet B,NB-UVB)通过促进维生素D(vitamin D,VD)代谢缓解咪喹莫特(imiquimod,IMQ)诱导银屑病样小鼠皮炎的效应机制。方法:C57BL/6小鼠背部去毛外涂IMQ乳膏进行银屑病样皮炎的造模,检测小鼠血清中VD代谢产物25(OH)D_(3)和1,25(OH)_(2)D_(3)的含量,以及皮损中VD受体(vitamin D receptor,VDR)mRNA表达;确定NB-UVB照射小鼠的辐照能量后,进行造模联合NB-UVB照射,观察小鼠皮损,检测血清中25(OH)D_(3)和1,25(OH)_(2)D_(3)的含量、皮损中VDR和炎症因子[白细胞介素(interleukin,IL)-17A、IL-23、肿瘤坏死因子(tumor necrosis factor,TNF)-α、IL-1β]的mRNA表达及蛋白含量及CD_(3)^(+)CD4^(+)IL-17A^(+)T细胞比例。使用特异性抑制剂Dafadine-A阻断小鼠VD代谢关键酶细胞色素P450家族27亚家族A成员1(cytochrome P450 family 27 subfamily A member 1,CYP27A1)活性后,再进行造模和NB-UVB照射,观察皮损,检测皮损中CD_(3)^(+)CD4^(+)IL-17A^(+)T细胞比例、炎症因子表达情况、VDR mRNA表达情况和血清中25(OH)D_(3)、1,25(OH)_(2)D_(3)的含量。结果:银屑病样小鼠模型血清中25(OH)D_(3)、1,25(OH)_(2)D_(3)含量和皮损中VDR的mRNA表达均显著降低。NB-UVB照射银屑病样小鼠模型后,相比模型组,小鼠血清中25(OH)D_(3)、1,25(OH)_(2)D_(3)含量和皮损中VDR的mRNA表达上调,皮损中炎症因子IL-17A、IL-23、TNF-α、IL-1β的表达及含量均下调、CD_(3)^(+)CD4^(+)IL-17A^(+)T细胞比例也显著下降。使用Dafadine-A预处理小鼠后进行造模联合NB-UVB照射,相比IMQ联合NB-UVB照射组,血清中25(OH)D_(3)、1,25(OH)_(2)D_(3)含量和皮损中VDR的mRNA表达均显著降低,皮损中CD_(3)^(+)CD4^(+)IL-17A^(+)T细胞比例和炎症因子IL-17A、IL-23、TNF-α、IL-1β的含量均显著升高。结论:NB-UVB照射通过促进VD代谢缓解银屑病样小鼠皮肤炎症。特异性阻断VD代谢关键酶CYP27A1活性后,NB-UVB照射缓解银屑病样小鼠皮损及炎症反应的效应显著减弱。
