水流对莲草直胸跳甲种群存活和扩散的影响

【背景】水流是外来入侵生物传播蔓延的重要方式之一,特别是水生生物。水生杂草在水流传播过程中也经常携带其天敌从一个地方传播到另一个地方,如莲草直胸跳甲经常随着空心莲子草在水流中传播。研究水流对莲草直胸跳甲存活的影响及其对种群迁移的间接协助作用,可为解析该天敌抵御洪涝灾害和借助水流传播的能力提供科学依据。【方法】本研究以莲草直胸跳甲为研究对象,在室内进行水流模拟,比较水流转速（1000、1250和1750r.min-1）和时间（30、60、90和120min）对不同虫态莲草直胸跳甲（雌雄成虫、幼虫和卵）存活率的影响,并推算莲草直胸跳甲成虫和幼虫在野外随水流传播的最大距离。【结果】水流速度对昆虫的存活和发育具有一定影响。在不同旋转时间和转速下,雌雄成虫的存活率较高,幼虫次之,卵的存活率最低;雌虫随水流传播能达到的最远距离最大,雄虫次之,传播距离最小的是幼虫。【结论与意义】莲草直胸跳甲可随水流进行远距离传播和自然扩散,对于利用莲草直胸跳甲防治空心莲子草,缓解水渠和河道的堵塞非常有利。     

Water‐use efficiency in response to climate change: from leaf to ecosystem in a temperate steppe

Water‐use efficiency (WUE) has been recognized as an important characteristic of ecosystem productivity, which links carbon (C) and water cycling. However, little is known about how WUE responds to climate change at different scales. Here, we investigated WUE at leaf, canopy, and ecosystem levels under increased precipitation and warming from 2005 to 2008 in a temperate steppe in Northern China. We measured gross ecosystem productivity (GEP), net ecosystem CO₂ exchange (NEE), evapotranspiration (ET), evaporation (E), canopy transpiration (T_c), as well as leaf photosynthesis (P_max) and transpiration (T_l) of a dominant species to calculate canopy WUE (WUE_c=GEP/T), ecosystem WUE (WUE_gep=GEP/ET or WUE_nee=NEE/ET) and leaf WUE (WUE_l=P_max/T_l). The results showed that increased precipitation stimulated WUE_c, WUE_gep and WUE_nee by 17.1%, 10.2% and 12.6%, respectively, but decreased WUE_l by 27.4%. Climate warming reduced canopy and ecosystem WUE over the 4 years but did not affect leaf level WUE. Across the 4 years and the measured plots, canopy and ecosystem WUE linearly increased, but leaf level WUE of the dominant species linearly decreased with increasing precipitation. The differential responses of canopy/ecosystem WUE and leaf WUE to climate change suggest that caution should be taken when upscaling WUE from leaf to larger scales. Our findings will also facilitate mechanistic understanding of the C–water relationships across different organism levels and in projecting the effects of climate warming and shifting precipitation regimes on productivity in arid and semiarid ecosystems.     

Community structure and composition in response to climate change in a temperate steppe

Climate change would have profound influences on community structure and composition, and subsequently has impacts on ecosystem functioning and feedback to climate change. A field experiment with increased temperature and precipitation was conducted to examine effects of experimental warming, increased precipitation and their interactions on community structure and composition in a temperate steppe in northern China since April 2005. Increased precipitation significantly stimulated species richness and coverage of plant community. In contrast, experimental warming markedly reduced species richness of grasses and community coverage. Species richness was positively dependent upon soil moisture (SM) across all treatments and years. Redundancy analysis (RDA) illustrated that SM dominated the response of community composition to climate change at the individual level, suggesting indirect effects of climate change on plant community composition via altering water availability. In addition, species interaction also mediated the responses of functional group coverage to increased precipitation and temperature. Our observations revealed that both abiotic (soil water availability) and biotic (interspecific interactions) factors play important roles in regulating plant community structure and composition in response to climate change in the semiarid steppe. Therefore these factors should be incorporated in model predicting terrestrial vegetation dynamics under climate change.     

阿德福韦酯联合拉米夫定治疗乙型肝炎DNA阳性肝硬化疗效观察

目的：探讨阿德福韦酯联合拉米夫定治疗HBV DNA阳性乙型肝炎肝硬化的疗效。方法：46例HBV DNA阳性乙肝肝硬化患者随机分为对照组及观察组。在保肝等对症治疗基础上,观察组22例患者联用阿德福韦酯与拉米夫定,对照组24例患者予阿德福韦酯,总疗程均为48周。结果：在治疗12周后,观察组与对照组HBV DNA转阴率分别为54.5%、20.8%（P〈0.05）,ALT复常率分别为63.6%、33.3%（P〈0.05）。治疗24周、48周后上述指标无统计学差异。两组患者未见明显药物不良反应。结论：阿德福韦酯联合拉米夫定治疗HBV DNA阳性乙型肝炎肝硬化起效快,降低病毒载量疗效佳,安全性好。     

NaCl胁迫对甘草生长及抗氧化酶活性的影响

目的：通过分析不同浓度NaCl胁迫下甘草生长和抗氧化酶活性的变化探讨甘草对盐分胁迫的适应性机理;方法：采用不同浓度的NaCl溶液（配成Hoagland液）处理盆栽一年生甘草,分别于35d、70d和105d取样,测定甘草株高、地上部分鲜、干重、根鲜、干重及甘草叶片SOD、POD、CAT活性,分析各生长指标与抗氧化酶活性的相关性;结果：NaCl胁迫70d和105d,0．6％和0．9％处理组的株高、地上部分鲜、干重及根鲜、干重均显著低于CK,SOD、POD及CAT活性均显著高于CK,经相关性分析得知,SOD、POD及CAT活性与各生长指标均负相关,其中POD活性与各生长指标极显著负相关;结论：甘草对NaCl胁迫的响应有胁迫时间和浓度的依赖性,在遭遇胁迫时,通过改变自身的生长和提高抗氧化酶活性,来提高机体的抗盐能力。     

酪氨酸羟化酶与视网膜疾病

酪氨酸羟化酶（tyrosine hydroxylase,TH）是儿茶酚胺（catech01amines,CAs）合成过程中的限速酶,提高或抑制该酶的活性可大幅度影响CAs的合成。近年来对于TH的关注越来越多,大量的研究表明,TH含量及活性的异常改变能通过影响CAs的含量而导致相应生理功能的异常,从而导致疾病。本文将TH的结构功能、分布、表达变化及其与视网膜疾病关系做一综述。     

广聚萤叶甲和豚草卷蛾对广西来宾豚草的联合控制作用

【背景】豚草已成功入侵广西来宾,对当地生物多样性、农业生产和居民健康造成了严重影响。广聚萤叶甲和豚草卷蛾均为豚草的重要专一性天敌,在湖南等地已有效抑制了豚草的扩散蔓延。【方法】为考查2种天敌在广西对豚草的联合控制作用,于2009年5月24日在广西来宾豚草入侵地区同时释放广聚萤叶甲和豚草卷蛾(2种天敌释放密度均为1170头.hm-2)。【结果】至2009年8月29日释放区内豚草植株死亡率达98%以上,且天敌迅速向邻近豚草发生区扩散,2种天敌对扩散区豚草的控制率可达50%～60%。【结论与意义】2种天敌对豚草具有显著的控制效果,建议在广西大面积推广应用。     

应用反向线点杂交技术鉴定临床常见曲霉属和毛霉目真菌

目的应用反向线点杂交技术(reverse line blot hybridization,RLB)快速鉴定临床常见的曲霉属和毛霉目真菌。方法收集我院真菌和真菌病研究中心保存的5种曲霉菌(烟曲霉、黄曲霉、黑曲霉、土曲霉、构巢曲霉)和7种毛霉目真菌(冻土毛霉菌、总状毛霉菌、卷枝毛霉菌、少根根霉、小孢根霉、微小根毛霉、伞状犁头霉),共计98株菌株。利用真菌通用引物ITS1和ITS4对菌株进行PCR扩增,用12个真菌种特异性探针与扩增后产物进行反向线点杂交。将RLB结果与真菌传统形态学鉴定结果、ITS区DNA测序结果进行比较。结果 RLB可以正确鉴定98株实验菌株,与形态学方法和ITS区测序方法鉴定结果100%一致,种特异性探针之间未见交叉杂交,显示出该方法的高度敏感性和特异性。8株阴性对照菌株(白念珠菌、茄病镰刀菌、尖端赛多孢、马尔尼菲青霉、疣状瓶霉、棒曲霉、日本曲霉以及雅致小克银汉霉),使用RLB方法无法鉴定。通过烟曲霉基因组DNA浓度10倍倍比稀释法验证RLB的敏感性为1.8×10-3 ng/μL。结论 RLB技术为实验室早期快速诊断、鉴定临床常见的曲霉属和毛霉目真菌提供参考。     

普通裂褶菌真菌学及实验室研究进展

普通裂褶菌是一种条件致病菌,可侵犯人体多个器官多种组织,导致各种表现形式的疾病,如脑脓肿、脑膜炎、鼻窦炎、肺部真菌球、蜂窝肺、肺结节、甲真菌病等.由于普通裂褶菌感染引起的真菌病病例少见报道,临床医生对其认识不足,再加上某些实验室不具备鉴定条件,所以感染该菌的病例常被漏诊、误诊.现将近年来临床分离的普通裂褶菌株真菌学及实...     

伊曲康唑联合特比萘芬治疗孢子丝菌病疗效及其对病原真菌体外抗菌活性研究

目的 初步探讨伊曲康唑和特比萘芬联合治疗孢子丝菌病的疗效,评价两药体外联合对申克孢子丝菌菌丝相和酵母相的抗菌活性.方法 口服伊曲康唑200mg/d和特比萘芬250mg/d治疗孢子丝菌病;体外联合药敏试验采用棋盘微量稀释法,计算分数抑菌浓度(FIC)指数判定两药相互作用具有协同、拮抗或无关作用.结果 伊曲康唑和特比萘芬联...