近自然化改造对马尾松人工林土壤团聚体有机磷组分含量变化的影响

有机磷(Po)是土壤磷库的重要组成部分。为探究马尾松人工林近自然化改造对土壤团聚体Po分布特征的影响,该研究以南亚热带的马尾松纯林(PP)和近自然化改造后的马尾松-阔叶树种混交林(CP)为对象,采集0～10 cm土样后利用干筛法将其筛分为>2 mm、0.25～2 mm和<0.25 mm三部分粒径团聚体,并测定原土及各粒径团聚体中各Po组分、微生物生物量磷(MBP)含量和酸性磷酸酶(ACP)活性。结果表明:(1)CP的土壤Po组分与PP相比发生了变化,高稳定性有机磷(HRO-P)和中度活性有机磷(MLO-P)在原土以及各团聚体径级中均显著高于PP(P<0.05),而活性有机磷(LO-P)和中度稳定性有机磷(MRO-P)在CP和PP中并无显著差异,PP和CP各组分Po在原土和各团聚体径级中无明显变化规律。(2)各形态Po在PP中占比大小为HRO-P>MRO-P>MLO-P>LO-P,而在CP中为HRO-P>MLO-P>MRO-P>LO-P。(3)CP中的MBP含量和ACP活性在原土及各团聚体径级中均显著高于PP,并且随着团聚体径级的减小,ACP活性上升。(4)冗余分析发现,土壤有效磷(AP)、土壤团聚体平均重量直径(MWD)、MBP和全氮(TN)为土壤Po组分的主要驱动因子。综上认为,近自然化改造有利于马尾松人工林土壤中磷的积累与转化,该研究结果为马尾松人工林土壤质量和生产力的提升提供了理论依据。     

Management practices influence biocontrol potential of generalist predators in maize cropping systems

Intensification of conventional agriculture is a leading cause of negative environmental impact, loss of biodiversity, and reduced delivery of ecosystem services in agroecosystems. Maize, due to its growth habits and cultivation management, provides a poor habitat for beneficial arthropods. Several strategies are available to make maize cropping systems more sustainable and to promote biodiversity at field level. The present study evaluates the effects of various maize cropping systems – precisely, maize continuous monoculture, maize multiple cropping, and three mixed cropping systems (maize-runner bean, maize-sorghum, and maize-flower strips) – on generalist predators and their biological control potential. Overall, we found that the reference system with maize continuous monoculture and conventional crop management had the lowest activity of generalist predators compared in particular to the low-input mixed cropping systems. Higher activity density and biocontrol potential were found in the systems that provided a dense and permanent vegetation cover of the ground (i.e., maize/sorghum, maize/flower strip). Although these effects were not consistent for all the parameters investigated and for every sampling date, we conclude that generalist predators can benefit from more conservative management practices in maize systems, thereby enhancing their biological pest control potential. Furthermore, spatial intercropping may represent a valid alternative to the conventional monocultural crop system to support the delivery of biodiversity-mediated ecosystem services towards a more sustainable system.     

雄安新区多尺度生态安全格局构建框架

维持城市所处的生态系统格局与过程,使得城市生存和发展所依赖的关键生态系统服务实现供需平衡是保障城市生态安全的根本要求和基本前提。因此,城市生态安全不仅是城市本身的问题,还涉及到城市所处的流域、区域、国家等多个不同的空间尺度,具体由支撑城市及其发展的关键生态系统服务所涉及的生态过程所决定。对生态安全概念及研究进展进行了梳理和分析,在此基础上,提出了一个城市生态安全保障的生态系统服务研究框架,将维持城市生态安全的关键生态系统服务需求分为3个层次：一是水资源供给、食物生产、水质净化等城市生存所依赖的基础资源与基本环境维持相关的服务,二是土壤保持、水源涵养、防风固沙、固碳释氧、生物多样性等生态系统稳定和可持续性维持相关的生态系统稳定和调节类服务,三是生态休闲、微气候调节、降尘减噪、文化审美等人居环境与文化类服务。进而利用该框架,从不同需求层次分别对雄安新区生态安全保障的生态系统服务需求进行了分析,结合其自然地理特征和新区建设的社会经济发展情景,从新区城市、大清河流域和京津冀区域三个尺度提出了雄安新区生态安全格局构建框架,以及相应的保障对策和建议,包括从多尺度进行生态环境调控和管理,打破行政和地域边界限制;关注各尺度各关键生态系统服务的过程,加强生态环境要素的监测和预警;重视新区在人居环境改善层次的生态系统服务需求等。     

Molecular epidemiology demonstrates that imported and local strains circulated during the 2014 dengue outbreak in Guangzhou,China

The dengue virus(DENV) is a vital global public health issue. The 2014 dengue epidemic in Guangzhou, China, caused approximately 40,000 cases of infection and five deaths. We carried out a comprehensive investigation aimed at identifying the transmission sources in this dengue epidemic. To analyze the phylogenetics of the 2014 dengue strains, the envelope(E) gene sequences from 17 viral strains isolated from 168 dengue patient serum samples were sequenced and a phylogenetic tree was reconstructed. All 17 strains were serotype Ⅰ strains, including 8genotype Ⅰ and 9 genotype V strains. Additionally, 6 genotype Ⅰ strains that were probably introduced to China from Thailand before 2009 were widely transmitted in the 2013 and 2014 epidemics, and they continued to circulate until 2015, with one affinis strain being found in Singapore. The other 2 genotype Ⅰ strains were introduced from the Malaya Peninsula in 2014. The transmission source of the 9 genotype Ⅴ strains was from Malaysia in 2014. DENVs of different serotypes and genotypes co-circulated in the 2014 dengue outbreak in Guangzhou. Moreover, not only had DENV been imported to Guangzhou, but it had also been gradually exported, as the viruses exhibited an enzootic transmission cycle in Guangzhou.     

口腔中幽门螺杆菌PCR检测方法的建立

全世界大约有50%的人口感染幽门螺杆菌(Helicobacter pylori, Hp),Hp感染容易造成慢性胃炎、消化性溃疡、低度恶性胃MALT淋巴瘤及胃癌,对人类造成严重的危害。为寻求一种简便、准确、非创伤性的方法用于口腔中Hp的检测,本研究建立了口腔中幽门螺杆菌的PCR检测方法,并对建立的PCR方法的敏感性、特异性进行分析,并应用于检测唾液样品和牙菌斑共50份。结果显示,50份样品中,阳性率为82%。结果表明,本研究建立的口腔中Hp的PCR检测方法特异性强、敏感性高,可以用于临床上Hp诊断的重要参考。     

基于生态系统服务功能的新疆绿洲生态安全格局识别及优化策略——以拜城县为例

识别生态保护关键区域,优化新疆县域生态空间结构,对促进绿洲区域经济与生态环境和谐发展,提升人类福祉具有重要意义。以拜城县为研究区,通过生态系统服务价值综合评定结果确定生态保护的核心"源"区,利用最小阻力模型,结合GIS空间分析技术及CA-Markov模型,识别拜城县生态安全格局,分析其发展变化趋势,探究生态空间布局调整策略,完善县域生态空间网络体系,结果表明:(1)研究期内,拜城县生态系统服务价值总量逐年上升,其中水源涵养、废物处理价值量增长最高,不同服务类型增长率差异较小。(2)分析2009、2016、2019拜城县生态安全格局特征发现,县域生态安全布局整体存在"源"地分布不均、廊道结构破碎且网络化程度低、生态脆弱区面积较大的现状特征。(3)基于2009、2016、2019年生态保护格局,同时依据生态"源"地及生态保护重要性用地的变化趋势,模拟2029年生态"源"地及其重要性等级区域分布,结合县域自然地理特征及总体发展规划,提出构筑"两带、三功能、四区、多中心、十廊道"的拜城县生态空间布局体系,为绿洲地区生态安全及区域生态文明建设提供参考。     

Covalently dimerized Camelidae antihuman TNFa single-domain antibodies expressed in yeast Pichia pastoris show superior neutralizing activity

Antagonists of tumor necrosis factor alpha (TNFa) have revolutionized the treatment of selected inflammatory diseases. Recombination Camelidae variable heavy-chain domain-only TNFa antibodies (anti-TNF-V_HH) have been developed to antagonize the action of human and murine TNFa. Here, we describe a strategy to obtain functional covalent dimer anti-TNF-V_HH molecules with the C-terminal fusion of human IgG1 Fc domain named anti-TNF-V_HH-Fc. The resulting fusion proteins were separately expressed by use of the pET28a vector in Escherichia coli ^(Ec) strain BL21 and the pPICZaA vector in Pichia pastoris ^(Pp) strain GS115, then purified by protein A affinity resin. Fc-engineered anti-^EcTNF-V_HH-Fc was about 40 kDa and anti-^PpTNF-V_HH-Fc was about 43 kDa. Monomeric V_HH was also cloned and expressed in E. coli strain BL21, with the molecular weight of about 18 kDa. Enzyme-linked immunosorbent assay and L929 cell cytotoxicity assay demonstrated that the fusion protein anti-^PpTNF-V_HH-Fc blocked TNFa activity more effectively than either anti-^EcTNF-V_HH-Fc or monomeric anti-^EcTNF-V_HH protein. We suggest that efficient disulfide bond formation using the P. pastoris expression system improves the covalent dimer anti-TNF-V_HH-Fc neutralizing activity.     

抑制水稻细菌性条斑病菌的没食子酸分离及其对水稻细菌性条斑病的防治作用

通过液—液萃取、硅胶和凝胶柱层析法,从佛甲草(Sedum lineare)分离出一种可以抑制水稻细菌性条斑病菌(Xanthomonas oryzae pv.oryzicola,Xoc)生长的单体化合物,经质谱分析,确定该化合物为没食子酸(gallic acid,GA)。在30 mg·m L-1浓度下,GA能抑制一些植物病原细菌如桃细菌性穿孔病菌(X.campestris pv.pruni)、水稻细菌性条斑病菌(X.oryzae pv.oryzicola)、水稻白叶枯病菌(X.oryzae pv.oryzae)、柑橘溃疡病菌(X.axonopodis pv.citri)、大豆细菌性斑点病菌(Pseudomonas syringae pv.glycinea)、番茄细菌性斑点病菌(P.syringae pv.tomato)和胡萝卜软腐果胶杆菌(Pectobacterium carotovora subsp.carotovora)的生长;GA还对11种植物病原真菌如烟草疫霉(Phytophthora nicotianae)、指状青霉(Penicillium digitatum)、滇刺枣褐腐病菌(Streptobotrys streptothrix)、瓜果腐霉(Pythium aphanidermatum)、芒果拟盘多毛孢(Pestalotiopsis mangiferae)、新月弯孢霉(Curvularia lunata)、立枯丝核菌(Rhizoctonia solani)、(Fusarium oxysporum f.sp.niverum)、西瓜专化型尖孢镰刀菌(F.oxysporum f.sp.nicotianae)、番茄灰霉病菌(Botrytis cinerea)和齐整小核菌(Sclerotium rolfsii)的生长具有一定的抑制作用。在300 mg·m L-1浓度下,GA对水稻细菌性条斑病的田间防治效果达到64.62%。该研究结果表明没食子酸具有开发成为一种防治水稻细菌性条斑病的杀菌剂的潜力。     

急性致死性对虾病的杆状病毒病原研究

近年来,上海郊区饲养中国对虾（Ｐｅｎａｃｕｓ ｃｈｉｎｅｓｉｓ ｏｓｂｅｃｋ）的虾塘发生大面积的流行病。经对病虾的鳃、肝、胰腺或中肠组织进行超薄切片处理及电镜观察。发现在这些组织的细胞核内存在大量有囊膜包裹的杆状病毒,有时一个囊膜还可同时包裹两个病毒的核衣壳。经有机溶剂处理、差速离心及密度梯度离心,可以获得部分提纯的病毒和病毒核衣壳制剂。超薄切片中,病毒粒子大小约为４４０－５００×１７０－１８０ｎ