冬季升温对高山生态系统碳氮循环过程的影响

全球温度升高是目前面临的重要环境问题,但存在明显的季节差异性,即冬季升温幅度显著高于夏季的季节非对称性趋势,这在高纬度和高海拔地区更加显著。冬季升温会直接影响积雪覆盖与冰冻层厚度,并引起冻融交替循环的增加,而冬季植物处于休眠状态,这会直接影响土壤中有效氮的吸收与损失,引起土壤有效氮可利用性的变化。然而,关于冬季增温对后续生长季节植物活动、土壤碳氮循环过程的影响等方面的研究仍存在诸多不确定。综述了冬季升温对积雪覆盖与冻融交替循环改变对高山生态系统物质循环的影响,以及冬季升温对土壤碳氮循环、微生物与酶活性的影响,并由此引起的植物物候期、群落结构、生产与养分循环与凋落物分解等生理、生态过程方面的研究进展。在未来的研究中,应针对不同生态系统特点选择合适的冬季增温方式,加强非极地苔原地区关于冬季升温的研究,注重关注冬季升温对植物-土壤微生物之间反馈作用的影响,重点关注冬季升温对生态系统的延滞效应。     

光氮互作对闽楠幼苗叶片光合生理特性的影响

以5月龄闽楠幼苗为材料,采用4种光照水平(100%、41.3%、14.3%、3.6%自然光)和4种氮素水平(0、0.5、1、2 mol/L纯氮)的双因素盆栽试验,研究光氮互作下闽楠幼苗的光合生理特性,以探讨其对环境适应性的生理机制。结果表明:(1)遮荫和施氮均能显著提高闽楠叶片光合色素含量;在同一氮素水平下,随光照强度下降,闽楠幼苗叶片可溶性糖(SS)、可溶性蛋白(SP)、净光合速率(P_n)、气孔导度(G_s)、最大净光合速率(P_(max))、暗呼吸速率(R_d)、表观量子系数(AQY)均呈先增后降趋势,并在41.3%自然光照水平时最高;而同期叶片胞间CO_2浓度(C_i)、蒸腾速率(T_r)、光饱和点(LSP)、光补偿点(LCP)均呈下降趋势;闽楠幼苗的叶片PSⅡ最大光化学效率(F_v/F_m)和PSⅡ潜在活性(F_v/F_o)则随光照减弱逐渐增加。(2)同一光照水平下,随着氮素施用量增加,闽楠幼苗叶片SS、SP、光合气体交换参数、光响应曲线特征参数总体呈现先升高后降低的趋势,F_v/F_m和F_v/F_o呈先降后增趋势。(3)不同光照和氮素水平之间存在显著的互作效应,隶属函数分析结果以41.3%自然光照、0.5 mol/L纯N处理的效果最优。研究表明,闽楠幼苗为喜光耐荫植物;适宜遮荫和施氮处理组合可显著改善闽楠渗透调节能力,提高光能利用率,促进光合作用进行,而全光照、过度遮荫、缺氮、或过量施氮均不利于闽楠正常生理代谢。     

近江牡蛎共附生耐热真菌C051的鉴定、生理学特性及抗菌活性研究

为进一步开发利用耐热海洋真菌,以1株近江牡蛎共附生耐热真菌C051为出发菌株,对其进行系统鉴定、生理学特性及抗菌活性研究。采用形态学鉴定并结合18S rRNA序列分析,确定菌株C051为烟曲霉(Aspergillus fumigatus)。3种培养基比较,适合基础培养基为PDA;生长温度范围为15～50℃,最适生长温度45℃,具有明显的耐热真菌特性;生长pH范围3～9,最适生长pH 6;生长盐浓度0%～16%,最适生长盐浓度3.5%,具兼性海洋真菌的特点。其发酵产物对铜绿假单胞菌(Pseudomons aeruginosa)、金黄色葡萄球菌(Staphylococcus aureus)、交替假单胞菌属SL-1(Pseudoalteromonas sp.)、金黄杆菌属SL-4(Chryseobacterium sp.)均有良好的抑菌效果,最大抑菌圈直径达22.15 mm,为耐热海洋真菌的开发与研究提供参考。     

Model-based design and control of a small-scale integrated continuous end-to-end mAb platform

A continuous integrated bioprocess available from the earliest stages of process development allows for an easier, more efficient and faster development and characterization of an integrated process as well as production of small-scale drug candidates. The process presented in this article is a proof-of-concept of a continuous end-to-end monoclonal antibody production platform at a very small scale based on a 200 ml alternating tangential flow filtration perfusion bioreactor, integrated with the purification process with a model-based design and control. The downstream process, consisting of a periodic twin-column protein A capture, a virus inactivation, a CEX column and an AEX column, was compactly implemented in a single chromatography system, with a purification time of less than 4 hr. Monoclonal antibodies were produced for 17 days in a high cell density perfusion culture of CHO cells with titers up to 1.0 mg/ml. A digital twin of the downstream process was created by modelling all the chromatography steps. These models were used for real-time decision making by the implementation of control strategies to automatize and optimize the operation of the process. A consistent glycosylation pattern of the purified product was ensured by the steady state operation of the process. Regarding the removal of impurities, at least a 4-log reduction in the HCP levels was achieved. The recovery yield was up to 60%, and a maximum productivity of 0.8 mg/ml/day of purified product was obtained.     

Maximizing antibody production in a targeted integration host by optimization of subunit gene dosage and position

Historically, therapeutic protein production in Chinese hamster ovary (CHO) cells has been accomplished by random integration (RI) of expression plasmids into the host cell genome. More recently, the development of targeted integration (TI) host cells has allowed for recombination of plasmid DNA into a predetermined genomic locus, eliminating one contributor to clone-to-clone variability. In this study, a TI host capable of simultaneously integrating two plasmids at the same genomic site was used to assess the effect of antibody heavy chain and light chain gene dosage on antibody productivity. Our results showed that increasing antibody gene copy number can increase specific productivity, but with diminishing returns as more antibody genes are added to the same TI locus. Random integration of additional antibody DNA copies in to a targeted integration cell line showed a further increase in specific productivity, suggesting that targeting additional genomic sites for gene integration may be beneficial. Additionally, the position of antibody genes in the two plasmids was observed to have a strong effect on antibody expression level. These findings shed light on vector design to maximize production of conventional antibodies or tune expression for proper assembly of complex or bispecific antibodies in a TI system.     

气囊在细菌中的生理功能、生物合成及应用研究进展

气囊是在水生细菌中广泛存在的一种具有刚性中空蛋白结构的特殊细胞器,不仅为水生细菌提供浮力,还对其在不利环境或应激条件下的生存至关重要。近期研究发现在其他非水生细菌如沙雷氏菌和链霉菌中也存在气囊结构,而且表现出不同的生理功能。来源于不同种属细菌的气囊生物合成基因簇具有各自鲜明的特征,其生物合成和调控机制也有所不同。本综述将介绍和总结不同细菌中气囊的基本生理功能和生物合成及调控机制,以及气囊的生物技术应用,并对气囊在链霉菌中的生物合成研究以及人工重组气囊的潜在应用进行展望。     

Physiological dormancy in seeds of tropical montane woody species in Hawai`i

Worldwide, there is relatively little information on seed dormancy and germination of tropical montane species. Our aim was to help fill this knowledge gap by conducting seed dormancy/germination studies on woody species from this vegetation zone in Hawai`i. All species had water-permeable seeds with a fully developed embryo. Seeds of 29 species (23 genera) were incubated in light/dark at 15/6, 20/10 and 25/15°C and germination monitored at 2-week intervals for 16–128 weeks. Seeds of Chenopodium oahuense, Dubautia menziesii and Silene lanceolata were non-dormant (ND) and those of 26 other species had physiological dormancy (PD); 10 of the 26 species had conditional PD. The optimum germination temperature regime(s) was (were) 25/15°C, 17 species; 25/10 and 20/10°C, 2; 20/10°C, 6; 20/10 and 15/6°C, 2; and 15/6°C, 2. Worldwide, PD in the woody genera included in our study is more common than ND. In addition to its contribution to the world biogeography of seed dormancy/germination, this study will be useful to conservation biologists who need to germinate seeds of tropical montane species.     

高浓度臭氧胁迫两种园林观赏草的逆境生理特征比较

以两种常见园林观赏草：白穗狼尾草（Pennisetum alopecuroides ‘White’）和拂子茅（Calamagrostis epigeios）作为试验材料,利用开顶箱（OTCs）模拟法,研究了不同高浓度臭氧（O₃,EO）：80 nmol/mol（EO-80）、120 nmol/mol（EO-120）和160 nmol/mol（EO-160）下两种观赏草叶片逆境生理特征的变化规律。结果表明：（1）短期（7 d）内随O₃浓度增加,白穗狼尾草叶绿素和类胡萝卜素含量较对照呈下降趋势,拂子茅较对照无显著变化。（2）在EO-120、EO-160下处理7 d时,两种观赏草叶片的净光合速率（P_n）和气孔导度（g_s）较对照显著下降,且白穗狼尾草下降的幅度均大于拂子茅。（3）不同高浓度O₃胁迫下,两种观赏草叶片丙二醛（MDA）含量较对照均有所升高,其中在EO-160下处理21 d时白穗狼尾草和拂子茅叶片MDA含量分别增加30.2%（P<0.05）和13.5%（P>0.05）,表明在EO-160浓度胁迫下白穗狼尾草受到的膜脂过氧化伤害大于拂子茅。（4）在EO-120和EO-160下处理21 d时,白穗狼尾草叶片可溶性蛋白含量较对照分别显著下降24.2%和43.1%,而拂子茅较对照分别下降19.0%和22.9%（P<0.05）。（5）与对照组相比,高浓度O₃下两种观赏草叶片的过氧化物酶（POD）活性随胁迫时间延长呈下降趋势,超氧化物歧化酶（SOD）活性呈先升后降。（6）综合以上生理特征比较及主成成分分析表明,佛子茅比白穗狼尾草更耐O₃,前者在O₃高污染地区可能会有更高的应用价值。     

宏观生态系统科学整合研究的多学科知识融合及其技术途径

综合认识大尺度的宏观生态系统结构功能、空间变异和动态演变的过程机理和模式机制,实现对生态系统变化及其对人类福祉影响的定量模拟、科学评估和预测预警,服务生态系统的利用保护及调控管理,是当代宏观生态系统科学的重要发展方向,正在孕育并形成大尺度的宏观生态系统科学整合生态学(IEMES)研究新领域。本研究通过对宏观生态系统科学整合生态学研究的基础理论、多学科知识融合途径及其关键技术问题的系统分析,形成以下几个基本认识: 1)宏观生态系统科学整合生态学研究是以区域、大陆和全球尺度的宏观生态系统为研究对象,采用多学科知识融合方法和技术,致力于解决人类社会发展的食物安全、资源安全、生态安全、环境安全等重大资源环境问题。2)宏观生态系统科学整合生态学研究的基本科技任务是: 理解宏观生态系统的结构功能基本属性,监测生态系统状态变化,解释生态系统时空演变规律,认知生态系统运维过程机理,定量评估生态系统功能状态及服务能力,预测生态系统动态演变及地理格局,预警生态系统变化及生态环境灾害。3)宏观生态系统科学整合生态学研究需要重新构造“多源数据分析-多模型模拟-多学科知识融合”的理论和方法学体系,发展“多尺度观测、多方法印证、多过程融合、跨尺度模拟”的多学科知识融合关键技术。4)大陆尺度的地基-空基-天基多时空尺度生态系统观测试验网络是承载多学科知识深度融合研究的基础科技设施,需要围绕区域、大陆和全球尺度的宏观生态系统科学问题,发展多要素-多过程-多界面-多介质-多尺度-多方法的多学科维度生态学知识融合关键技术。     

盐胁迫下解钾菌对枸杞幼苗的促生效应

以‘宁杞1号’枸杞为研究对象,采用单因素随机区组试验设计,研究不添加NaCl和菌剂(CK)、100 mmol·L^-1 NaCl胁迫(NaCl)、100 mmol·L^-1 NaCl胁迫下添加解钾菌KSBGY01单菌液(NaCl-M1)、KSBGY02单菌液(NaCl-M2)及其混合菌液(NaCl-M3)对枸杞幼苗叶片叶绿素、多酚、超氧阴离子(O₂^-·)、过氧化氢(H₂O₂)和可溶性糖含量、抗氧化物酶和蔗糖代谢酶活性的影响,以探索解钾菌对盐胁迫下枸杞生理生化特性的影响。结果表明: 盐胁迫下解钾菌能够提高枸杞叶片类黄酮(FLAV)、荧光激发比花青素相对指数(FERARI)、花青素(ANTH-RB)和氮素平衡指数(NBI-G),降低O₂^-·和H₂O₂含量,增加可溶性糖含量及过氧化氢酶(CAT)、蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS)和转化酶(INV)活性。不同处理间比较,NaCl-M2处理中枸杞叶片ANTH-RB值、NBI-G值、可溶性糖含量及CAT、SPS、SS和INV活性最高;NaCl-M3处理中枸杞叶片叶绿素含量、FLAV和FERARI值最高;NaCl-M1处理中枸杞叶片超氧化物歧化酶(SOD)活性最高;不添加解钾菌的NaCl处理中枸杞叶片谷胱甘肽过氧化物酶(GSH-Px)活性最高;CK处理中枸杞叶片过氧化物酶(POD)活性最高。对枸杞幼苗14项生理生化指标进行灰色系统关联度分析表明,盐胁迫条件下添加解钾菌处理的枸杞生理生化指标加权关联度均高于CK和NaCl处理,其中NaCl-M2处理的加权关联度最高。因此,添加KSBGY02单菌液更有利于缓解盐胁迫对枸杞幼苗的影响。