The effects of simulated nitrogen(N)deposition on soil exchangeable cations were studied in three forest types of subtropical China.Four N treatments with three replications were designed for the monsoon evergreen bro...The effects of simulated nitrogen(N)deposition on soil exchangeable cations were studied in three forest types of subtropical China.Four N treatments with three replications were designed for the monsoon evergreen broadleaf forest (mature forest):control(0 kg N ha-1 year-1),low N(50 kg N ha-1 year-1),medium N(100 kg N ha-1 year-1)and high N(150 kg N ha-1 year-1),and only three treatments(i.e.,control,low N,medium N)were established for the pine and mixed forests.Nitrogen had been applied continuously for 26 months before the measurement.The mature forest responded more rapidly and intensively to N additions than the pine and mixed forests,and exhibited some significant negative symptoms,e.g.,soil acidification,Al mobilization and leaching of base cations from soil.The pine and mixed forests responded slowly to N additions and exhibited no significant response of soil cations.Response of soil exchangeable cations to N deposition varied in the forests of subtropical China,depending on soil N status and land-use history.展开更多
Three forests with different historical land-use, forest age, and species assemblages in subtropical China were selected to evaluate current soil N status and investigate the responses of soil inorganic N dynamics to ...Three forests with different historical land-use, forest age, and species assemblages in subtropical China were selected to evaluate current soil N status and investigate the responses of soil inorganic N dynamics to monthly ammonium nitrate additions. Results showed that the mature monsoon evergreen broadleaved forest that has been protected for more than 400 years exhibited an advanced soil N status than the pine （Pinus massoniana） and pine-broadleaf mixed forests, both originated from the 1930＇s clear-cut and pine plantation. Mature forests had greater extractable inorganic N pool, lower N retention capacity, higher inorganic N leaching, and higher soil C/N ratios. Mineral soil extractable NH4^＋-N and NO3-N concentrations were significantly increased by experimental N additions on several sampling dates, but repeated ANOVA showed that the effect was not significant over the whole year except NH4^＋-N in the mature forest. In contrast, inorganic N （both NH4^＋-N and NO3^--N） in soil 20-cm below the surface was significantly elevated by the N additions. From 42% to 74% of N added was retained by the upper 20 cm soils in the pine and mixed forests, while 0%-70% was retained in the mature forest. Our results suggest that land-use history, forest age and species composition were likely to be some of the important factors that determine differing forest N retention responses to elevated N deposition in the study region.展开更多
新型冠状病毒感染疫情发展迅速,中药在这场防治疫情的战争中发挥着积极作用,已有大量确有疗效的方剂应用于临床。然而由于中药具有多成分、多靶点、多途径协同作用的特点,传统的抗病毒中药筛选研究受限于实验室条件和实验周期,极大地限...新型冠状病毒感染疫情发展迅速,中药在这场防治疫情的战争中发挥着积极作用,已有大量确有疗效的方剂应用于临床。然而由于中药具有多成分、多靶点、多途径协同作用的特点,传统的抗病毒中药筛选研究受限于实验室条件和实验周期,极大地限制了筛选速度。该文基于分子对接进行潜在抗新型冠状病毒中药的筛选,通过获取2019-nCoV冠状病毒3CL水解酶(3CL protease,Mpro)和冠状病毒木瓜样蛋白酶(papain-like protease,PLP)的晶体结构,对中药化学成分数据库(traditional Chinese medicine database,TCMD 2009)进行基于分子对接的虚拟筛选,选择打分值排名前100的成分作为潜在抗新型冠状病毒活性的中药成分,并对成分来源中药进行频数统计,挑选命中成分数目较多的中药作为潜在抗新型冠状病毒活性的中药。研究结果显示,基于Mpro靶点筛选获得潜在抗新型冠状病毒活性成分12322个,代表性活性成分有紫菀五肽A、川芎嗪、丹酚酸B等,筛选得到的中药为生姜、紫菀、三七、川芎、丹参、干姜、瞿麦、大黄、肉苁蓉等;基于PLP靶点筛选获得潜在抗新型冠状病毒活性成分11294个,代表性活性成分有姜酮酚、白果醇、阿魏酸等,筛选得到的中药为党参、羌活、生姜、白果、川芎、瓜蒌、白芍、补骨脂、苦参、三七、当归等。结合文献报道的基于分子对接筛选的血管紧张素转换酶2(angiotensin converting enzyme 2,ACE2)靶点抑制活性候选中药,该文在湖南省新型冠状病毒肺炎中医药诊疗方案的基础上,将Mpro抑制、PLP抑制和ACE2抑制候选中药针对该疫情的合理应用进行了探讨,分析结果表明,PLP抑制活性筛选获得的瓜蒌及ACE2筛选获得的贝母包含于桑贝止嗽散、小陷胸汤之中,有清化热痰之功效,主治痰热壅肺所致的痰多咳喘或燥痰犯肺、干咳少痰、咯痰不爽,可应用于病毒作用初期外邪闭肺所致的咳嗽微喘等证型;Mpro抑制活性筛选获得的中药大黄佐以PLP筛选获得的瓜蒌,清泻腑气,二者包含于麻杏石甘汤、宣白承气汤中,可应用于疾病重症期邪热壅肺、疫毒闭肺以致腑实里结等证型;ACE2抑制活性筛选获得的中药桑叶、金银花及连翘包含于桑菊饮和银翘散中,轻清宣透,可应用于疾病初期温邪犯肺及咳嗽微喘等证型。研究结果旨在为进一步开展中医药应对新型冠状病毒疫情的治疗方案提供参考。展开更多
基金Project supported by the National Natural Science Foundation of China(No.30670392)the Knowledge Innovation Program of the Chinese Academy of Sciences(Nos.KZCX2-YW-432 and KSCX2-SW-133)
文摘The effects of simulated nitrogen(N)deposition on soil exchangeable cations were studied in three forest types of subtropical China.Four N treatments with three replications were designed for the monsoon evergreen broadleaf forest (mature forest):control(0 kg N ha-1 year-1),low N(50 kg N ha-1 year-1),medium N(100 kg N ha-1 year-1)and high N(150 kg N ha-1 year-1),and only three treatments(i.e.,control,low N,medium N)were established for the pine and mixed forests.Nitrogen had been applied continuously for 26 months before the measurement.The mature forest responded more rapidly and intensively to N additions than the pine and mixed forests,and exhibited some significant negative symptoms,e.g.,soil acidification,Al mobilization and leaching of base cations from soil.The pine and mixed forests responded slowly to N additions and exhibited no significant response of soil cations.Response of soil exchangeable cations to N deposition varied in the forests of subtropical China,depending on soil N status and land-use history.
文摘Three forests with different historical land-use, forest age, and species assemblages in subtropical China were selected to evaluate current soil N status and investigate the responses of soil inorganic N dynamics to monthly ammonium nitrate additions. Results showed that the mature monsoon evergreen broadleaved forest that has been protected for more than 400 years exhibited an advanced soil N status than the pine （Pinus massoniana） and pine-broadleaf mixed forests, both originated from the 1930＇s clear-cut and pine plantation. Mature forests had greater extractable inorganic N pool, lower N retention capacity, higher inorganic N leaching, and higher soil C/N ratios. Mineral soil extractable NH4^＋-N and NO3-N concentrations were significantly increased by experimental N additions on several sampling dates, but repeated ANOVA showed that the effect was not significant over the whole year except NH4^＋-N in the mature forest. In contrast, inorganic N （both NH4^＋-N and NO3^--N） in soil 20-cm below the surface was significantly elevated by the N additions. From 42% to 74% of N added was retained by the upper 20 cm soils in the pine and mixed forests, while 0%-70% was retained in the mature forest. Our results suggest that land-use history, forest age and species composition were likely to be some of the important factors that determine differing forest N retention responses to elevated N deposition in the study region.
文摘新型冠状病毒感染疫情发展迅速,中药在这场防治疫情的战争中发挥着积极作用,已有大量确有疗效的方剂应用于临床。然而由于中药具有多成分、多靶点、多途径协同作用的特点,传统的抗病毒中药筛选研究受限于实验室条件和实验周期,极大地限制了筛选速度。该文基于分子对接进行潜在抗新型冠状病毒中药的筛选,通过获取2019-nCoV冠状病毒3CL水解酶(3CL protease,Mpro)和冠状病毒木瓜样蛋白酶(papain-like protease,PLP)的晶体结构,对中药化学成分数据库(traditional Chinese medicine database,TCMD 2009)进行基于分子对接的虚拟筛选,选择打分值排名前100的成分作为潜在抗新型冠状病毒活性的中药成分,并对成分来源中药进行频数统计,挑选命中成分数目较多的中药作为潜在抗新型冠状病毒活性的中药。研究结果显示,基于Mpro靶点筛选获得潜在抗新型冠状病毒活性成分12322个,代表性活性成分有紫菀五肽A、川芎嗪、丹酚酸B等,筛选得到的中药为生姜、紫菀、三七、川芎、丹参、干姜、瞿麦、大黄、肉苁蓉等;基于PLP靶点筛选获得潜在抗新型冠状病毒活性成分11294个,代表性活性成分有姜酮酚、白果醇、阿魏酸等,筛选得到的中药为党参、羌活、生姜、白果、川芎、瓜蒌、白芍、补骨脂、苦参、三七、当归等。结合文献报道的基于分子对接筛选的血管紧张素转换酶2(angiotensin converting enzyme 2,ACE2)靶点抑制活性候选中药,该文在湖南省新型冠状病毒肺炎中医药诊疗方案的基础上,将Mpro抑制、PLP抑制和ACE2抑制候选中药针对该疫情的合理应用进行了探讨,分析结果表明,PLP抑制活性筛选获得的瓜蒌及ACE2筛选获得的贝母包含于桑贝止嗽散、小陷胸汤之中,有清化热痰之功效,主治痰热壅肺所致的痰多咳喘或燥痰犯肺、干咳少痰、咯痰不爽,可应用于病毒作用初期外邪闭肺所致的咳嗽微喘等证型;Mpro抑制活性筛选获得的中药大黄佐以PLP筛选获得的瓜蒌,清泻腑气,二者包含于麻杏石甘汤、宣白承气汤中,可应用于疾病重症期邪热壅肺、疫毒闭肺以致腑实里结等证型;ACE2抑制活性筛选获得的中药桑叶、金银花及连翘包含于桑菊饮和银翘散中,轻清宣透,可应用于疾病初期温邪犯肺及咳嗽微喘等证型。研究结果旨在为进一步开展中医药应对新型冠状病毒疫情的治疗方案提供参考。
文摘新型冠状病毒(2019-nCoV)肺炎疫情暴发以来,发展迅速,形势严峻,受到国内外广泛关注。发表在《柳叶刀》杂志的研究指出新型冠状病毒的感染与"细胞因子风暴"(cytokine storm)存在密切联系。"细胞因子风暴"是机体对病毒、细菌等外界刺激产生的一种过度免疫反应。当病毒攻击机体时,刺激分泌产生大量的炎症因子,如白细胞介素(interleukin,IL)、干扰素(interferon,IFN)、趋化因子(C-X-C motif chemokine,CXCL)等,进而引发细胞因子级联反应。随着炎症因子渗出,多种细胞因子在组织、器官中异常升高,干扰免疫系统,造成机体过度免疫应答反应,引起肺部细胞的弥漫性损伤,肺部出现纤维化,且导致多器官损伤,严重则可能导致死亡。花生四烯酸(arachidonic acid,AA)代谢通路主要用于合成炎症介质,可介导多种炎症因子的产生,如单核细胞趋化蛋白-1(monocyte chemotactic protein 1,MCP-1)、肿瘤坏死因子(tumor necrosis factor,TNF)、IL、IFN等,与炎症的发生发展及消退均有密切联系。因此抑制花生四烯酸代谢通路,有助于抑制机体炎症因子的释放,缓解"细胞因子风暴"。该研究基于花生四烯酸代谢通路关键靶点抑制剂的药效团模型,筛选中药化学成分数据库(traditional Chinese medicine database,TCMD 2009)。选择匹配值(fit value)大于0.7的成分作为潜在活性成分,对活性成分来源中药进行频数统计,结合《国家新型冠状病毒感染的肺炎诊疗方案(试行第六版)》中的中药方剂进行分析,获取对"细胞因子风暴"具有潜在治疗作用的方剂。结果显示,对花生四烯酸代谢通路具有抑制作用的成分为厚朴木脂体Ⅰ、忍冬苦苷、大黄素甲醚-8-O-β-D-吡喃葡萄糖苷等,中药为厚朴、生姜、金银花、大黄、丹参、黄芩、栀子、人参、牛蒡子、绵马贯众、赤芍、山药。结合新型冠状病毒治疗方剂进行分析,发现藿香正气胶囊、金花清感颗粒、连花清瘟胶囊、清肺排毒汤、血必净注射液、热毒宁注射液、痰热清注射液对花生四烯酸通路具有潜在抑制作用,可能通过缓解"细胞因子风暴"抑制新型冠状病毒引起的肺炎。该研究旨在为新型冠状病毒临床用药提供指导,并为探索治疗新型冠状病毒中药及方剂的治疗机制和临床用药提供参考。
