Identification and characterization of a chondroitin synthase from Avibacterium paragallinarum

Applied Microbiology and Biotechnology - Avibacterium paragallinarum is a Gram-negative bacterium that causes infectious coryza in chicken. It was reported that the capsule polysaccharides...     

Photobiomodulation by diffusing optical fiber on spinal cord: A feasibility study in piglet model

Previous studies on spinal cord injury (SCI) have confirmed that percutaneous photobiomodulation (PBM) therapy can ameliorate immunoinflammatory responses at sites of injury, accelerate nerve regeneration, suppress glial scar formation and promote the subsequent recovery of locomotor function. The current study was performed to evaluate a large‐animal model employing implanted optical fibers to accurately irradiate targeted spinal segments. The method's feasibility and irradiation parameters that do not cause phototoxic reaction were determined, and the methodology of irradiating the spinal cord with near‐infrared light was investigated in detail. A diffusing optical fiber was implanted above the T9 spinal cord of Bama miniature pigs and used to transfer near‐infrared light (810 nm) onto the spinal cord surface. After daily irradiation with 200, 300, 500 or 1000 mW for 14 days, both sides of the irradiated area of the spinal cord were assessed for temperature changes. The condition of the spinal cord and the position of optical fiber were investigated by magnetic resonance imaging (MRI), and different parameters indicating temperature increases or phototoxicity were measured on the normal spinal cord surface due to light irradiation (ie, heat shock responses, inflammatory reactions and neuronal apoptosis), and the animals' lower‐limb neurological function and gait were assessed during the irradiation process. The implanted device was stable inside the freely moving animals, and light energy could be directly projected onto the spinal cord surface. The screening of different irradiation parameters preliminary showed that direct irradiation onto the spinal cord surface at 200 and 300 mW did not significantly increase the temperature, stress responses, inflammatory reactions and neural apoptosis, whereas irradiation at 500 mW slightly increased these parameters, and irradiation at 1000 mW induced a significant temperature increase, heat shock, inflammation and apoptosis responses. HE staining of spinal cord tissue sections did not reveal any significant structural changes of the tissues compared to the control group, and the neurological function and gait of all irradiated animals were normal. In this study, we established an in‐vivo optical fiber implantation method, which might be safe and stable and could be used to directly project light energy onto the spinal cord surface. This study might provide a new perspective for clinical applications of PBM in acute SCI.     

耐药细菌蛋白质的分泌——新抗攻击的靶点

几十年来,由于抗生素的大量使用,导致了细菌对很多药物的抗药性.为了克服细菌的抗药性问题,需要用新的思路去发掘新的抗生素,包括发掘细菌细胞中存在的抗生素作用的新靶点.蛋白质的分泌过程对于细菌是生死攸关的,它可能成为新药物的适合靶点.     

NaF、NaBr、NaI对酵母朊病毒[PSI~+]形成的影响

为研究NaF、NaBr、NaI对酵母朊病毒[PSI+]形成的影响,利用表达融合蛋白GFP-Sup35p酵母朊病毒模型,借助半变性琼脂糖凝胶电泳技术,结合免疫印迹方法在蛋白水平上定量分析NaF、NaBr、NaI对酵母朊病毒[PSI+]形成的影响。结果显示,在细胞表型方面NaF、NaBr诱导出酵母朊病毒[PSI+],且所需浓度分别为0.02、1.0 mol/L;NaI在浓度为0.25 mol/L可以诱导出[PSI+]经盐酸胍治愈后的酵母朊病毒[psi-]。在蛋白水平,NaF、NaBr、NaI盐作用后的[psi-]细胞内Sup35p并没有形成聚集体。     

Self-assembly of Large-scale Two-dimensional Plasmonic Superlattices Based on Single-Crystal Au Nanospheres and the FDTD Simulation of Its Optical Properties

Plasmonics - Large-scale ordered two-dimensional (2D) superlattices at oil/water interface were fabricated using single-crystal Au nanospheres (NSs) with different diameters as building blocks. A...     

重庆市生态风险预警等级划分及演化趋势模拟

生态风险预警等级评估和演化趋势模拟，可为生态风险管理提供可靠的辅助决策。以重庆市为研究对象，基于驱动力-压力-状态-影响-响应模型，构建重庆市生态风险预警指标体系，采用正态云模型和集对分析法，定量分析重庆市生态风险时空分异特征和演化趋势。研究结果表明：（1）2013-2019年，重庆市生态风险值呈"上升-下降"的波动趋势，综合生态风险隶属于重警等级，生态风险综合值从0.295下降到0.278，生态环境逐年好转；（2）重庆市生态风险有下降、不变、先上升后降低、先降低后上升以及一直升高5种演化趋势，分别占比39%、16%、5%、21%、24%；（3）重庆市生态风险转移分为两个方向，2013-2016年生态风险空间分异性增大，中警、轻警和无警风险等级不断向东北、东南和西部四周分散转移；2016-2019年生态风险分布格局变化较小，重警风险区在东部聚集；（4）演化趋势模拟结果表明，未来重庆市生态风险降低的区县有13个，占比34%，生态环境有向好发展的趋势；生态风险上升的区县有25个，占比66%，生态环境会有所恶化，但是恶化程度较低。将生态风险等级划分与预警演化趋势相结合，能为城市生态风险管理提供科学依据。     

接种丛枝菌根真菌对云南石漠化土壤呼吸的影响

为探明"丛枝菌根（Arbuscular mycorrhiza，AM）真菌-植物-土壤"耦合作用对石漠化土壤呼吸季节动态的影响，采用LI-6400-09土壤呼吸室和便携式光合作用测量系统，对圆柏（Sabina chinensis）接种摩西斗管囊霉（Funneliformis mosseae，FM）、根内根孢囊霉（Rhizophagus intraradices，RI）2种AM菌种处理下土壤呼吸季节动态进行野外连续定位观测，并探究AM真菌接种处理下石漠化土壤呼吸速率与植物生长、土壤理化性质之间的关系。结果表明：（1）相较于对照，接种AM真菌对石漠化生境土壤呼吸季节动态产生了显著影响（P<0.01）。AM真菌处理具有较高的土壤呼吸季节变化幅度，即根内根孢囊霉处理土壤呼吸速率（1.55-9.10 μmol m^-2 s^-1）显著高于摩西斗管囊霉（1.62-8.29 μmol m^-2 s^-1）和对照（1.23-4.46 μmol m^-2 s^-1）；（2） AM真菌接种处理下土壤温湿度变化对土壤呼吸的影响显著大于对照，即土壤温度与水分对土壤呼吸的平均解释量大小顺序为：RI （44.84%；52.35%）>FM （17.18%；41.65%）>CK （2.66%；16.55%）；（3）2种菌种处理下土壤呼吸速率均与土壤有机质、硝态氮、全氮、速效钾、树高、胸径及根系生物量呈显著或极显著正相关（P<0.01或0.05），而与pH呈极显著负相关（P<0.01），但对照处理土壤呼吸速率除与pH呈显著负相关（P<0.05）外，与其它土壤理化指标相关性不显著；（4）土壤温度和水分、硝态氮、铵态氮、有机质、易氧化有机碳、速效钾、全氮及全磷对土壤呼吸变化的贡献最大，而胸径、树高、有效磷、微生物生物量、根系生物量及pH的影响次之。因此，"AM真菌-寄主植物-土壤"相互作用对石漠化生境土壤呼吸季节动态的影响，主要取决于不同AM真菌接种处理对土壤微气候（如含水量）、碳素（有机质、易氧化有机碳）、无机氮库（铵态氮、硝态氮）、根系生物量及磷钾养分可利用性的调控。     

Urban Household Carbon Emission and Contributing Factors in the Yangtze River Delta,China

Carbon reduction at the household level is an integral part of carbon mitigation. This study analyses the characteristics, effects, contributing factors and policies for urban household carbon emissions in the Yangtze River Delta of China. Primary data was collected through structured questionnaire surveys in three cities in the region – Nanjing, Ningbo, and Changzhou in 2011. The survey data was first used to estimate the magnitude of household carbon emissions in different urban contexts. It then examined how, and to what extent, each set of demographic, economic, behavioral/cognitive and spatial factors influence carbon emissions at the household level. The average of urban household carbon emissions in the region was estimated to be 5.96 tonnes CO₂ in 2010. Energy consumption, daily commuting, garbage disposal and long-distance travel accounted for 51.2%, 21.3%, 16.0% and 11.5% of the total emission, respectively. Regulating rapidly growing car-holdings of urban households, stabilizing population growth, and transiting residents’ low-carbon awareness to household behavior in energy saving and other spheres of consumption in the context of rapid population aging and the growing middle income class are suggested as critical measures for carbon mitigation among urban households in the Yangtze River Delta.