CO2 efflux by rapid decomposition of low molecular organic substances in soils

Decomposition rates of the [2-¹⁴C]-glucose and [2-¹⁴C]-glycine in four different soils of the long-term field trial of Moscow were investigated in a 3-months laboratory experiment in which ¹⁴CO₂ respiration was measured. A model with three decomposition components and two distribution parameters was developed and validated with the data of the experiment. The decay rate constants of free [2-¹⁴C]-glucose (4–32 day^-1) were slower than those of [2-¹⁴C]-glycine (16–44 day^-1). The calculated use efficiency for microbial biosynthesis of the second carbon atom was 47% for glucose and 31% for glycine. The potential half-life of labelled carbon in the microbial soil biomass ranged from 0.6 to 4.4 days, depending on the soil type and the initial amount of added substrate. The calculated total utilisation of carbon by the soil biomass from glycine was about 2–5 times lower than that of glucose.The modelled ¹⁴C incorporation into the microbial soil biomass reached its maximum on the first day of the incubation experiment and did not exceed 22% of the ¹⁴C input. Both of the investigated substances decomposed most rapidly in the soil samples from sites that have not being fertilised with organic or mineral fertilisers during an 81-years period.     

Priming effects of sugars,amino acids,organic acids and catechol on the mineralization of lignin and peat

The ¹⁴C‐labeled substrates glucose, fructose, alanine, glycine, oxalic acid, acetic acid, and catechol were incubated at 20 °C in a model system that consisted of sand mixed with lignin or peat (3 % C_org). Each substrate was added at either 80 or 400 μg C (g sand)^—1. During 26 days of incubation with an inoculum extracted from forest soil, the amount of CO₂ evolved was measured hourly. The amount of ¹⁴CO₂ was determined after 4, 6, 12, 19, and 26 days. After 26 days of incubation, each substrate showed priming effects, but not in all examined treatments. Most substrates stimulated the degradation of the model substances (positive priming effects). Negative priming effects only were found in the lignin system with oxalic acid and catechol addition at both concentrations. The strongest positive priming occurred in the peat system with the oxalic acid addition of 80 μg C g^—1 where 1.8 % of the peat were mineralized after 26 days, compared to 0.7 % in the control. The addition of 400 μg alanine‐C g^—1 caused the strongest increase in lignin mineralization, amounting to 3.9 % compared to 2.8 % in the control. During the incubation the extent of priming changed with time. Most substrates caused the strongest effects during the first 4 to 10 days of incubation. The extent of priming depended on substrate type, substrate concentration, and organic model substance. Possibly this is due to the activation of different microorganisms.     

斯氏艾美耳球虫重组表面抗原SAG13和SAG14对兔的免疫保护效果初步观察

本研究旨在观察斯氏艾美耳球虫裂殖生殖阶段特异性表面抗原Es-SAG13和Es-SAG14的原核表达产物对兔的免疫保护效果.利用相对荧光定量PCR分析Es-SAGs在未孢子化卵囊时期、孢子化卵囊时期、裂殖生殖时期和配子生殖时期的转录水平,并对裂殖生殖阶段特异性表达的Es-SAG进行原核表达;然后将40只45日龄无球虫幼兔...     

牦牛CCL14蛋白对HepG2细胞活性和凋亡的影响

旨在研究牦牛CCL14蛋白（Bos grunniens C-C motif chemokine 14 protein, BgCCL14）对HepG2细胞的影响和作用机制。将原核表达的BgCCL14蛋白与HepG2细胞共培养，利用CCK-8试剂盒检测细胞活性，平板克隆检测细胞克隆形成能力，细胞划痕检测细胞迁移以及荧光定量PCR检测相关基因的表达量。结果表明，1 μg/mL、10 μg/mL和20 μg/mL的BgCCL14蛋白均能显著降低HepG2细胞活性；20 μg/mL的BgCCL14蛋白对细胞增殖和迁移有极显著抑制作用；20 μg/mL的BgCCL14蛋白处理36 h极显著上调凋亡基因BAK和BAX 的mRNA水平，极显著降低 HIF1A、 PI3K和 CDK1基因的mRNA水平，显著降低mTOR基因 的mRNA水平。这表明BgCCL14蛋白可能通过促进细胞凋亡抑制肝癌细胞活性。     

甘肃省杏种业“十四五”发展对策

为保证甘肃省杏产业健康高效发展，通过总结“十三五”甘肃省杏种业取得的主要成效和经验，分析了“十四五”甘肃省杏种业发展面临的机遇与挑战。从发展定位和指导思想两个方面提出了“十四五”甘肃省杏种业发展的总体思路，并从加强杏种质资源收集和保存、杏种质资源深入评价和种质创新、重点培育杏优良新品种、开展杏新品种联合区试、加强品种保护及加快成果转化5个方面指出了“十四五”甘肃省杏种业的研究重点。最后从稳定经费支持、创新体制机制、加强人才培养、改善科研条件等方面提出了“十四五”甘肃省杏种业发展的保障措施。     

铜绿假单胞菌PA14 H3-T6SS的调控功能研究

【目的】研究模式病原细菌铜绿假单胞菌PA14（Pseudomonas aeruginosa PA14）第三套六型分泌系统（H3-T6SS）的调控机制和在环境适应等方面的功能，为该菌致病机制研究和治疗方案开发奠定基础。【方法】以铜绿假单胞菌PA14为研究对象，利用凝胶迁移阻滞试验（EMSA）验证σ^s因子（RpoS）与H3-T6SS启动子区的结合能力；构建rpoS敲除菌株（ΔrpoS）及回补菌株（rpoS），用启动子酶活试验研究RpoS对H3-T6SS表达的调控作用；构建H3-T6SS关键组分clpV3敲除菌株（ΔclpV3）及回补菌株（clpV3），测定其在酸、渗透压等不同胁迫下的细胞存活率；检测H3-T6SS对铜绿假单胞菌PA14生物膜形成和运动能力的影响。【结果】RpoS蛋白可以直接结合H3-T6SS启动子区；成功构建了铜绿假单胞菌PA14的rpoS和clpV3敲除菌株及回补菌株，RpoS正调控H3-T6SS的表达，H3-T6SS有助于细菌抵抗酸胁迫，但对渗透压胁迫响应不明显；H3-T6SS可显著增强细菌的生物膜形成和运动能力。【结论】铜绿假单胞菌PA14的H3-T6SS受调控因子RpoS的正调控，在增强细菌抗酸胁迫、生物膜形成和运动能力等方面有重要作用。     

“十四五”时期加快补齐农村道路建设短板

近年来，我国农村道路建设取得了显著成绩。截止2020年，具备条件的乡镇和建制村实现了100%通硬化路的目标，但还存在一些突出问题和短板，亟需加快补齐。文章系统研究我国农村道路建设现状，梳理现阶段农村道路建设存在的问题，提出加强农村道路建设、加快补齐农村道路短板的思路和对策。我国农村道路建设在取得显著成绩的同时，也存在一些突出问题和短板，村内道路无人管无人建、建设标准缺失、资金缺口巨大，农村道路管理养护滞后，技术等级不高，配套设施不健全，交通隐患较多，等等，亟待转变建设思路，加强对策研究，加快补齐短板，促进农民脱贫致富。加快补齐农村道路建设短板，应从六个方面精准施策，实现农村道路建设“六大转变”，才能更好地为农民群众便捷出行、农村地区经济社会发展提供强有力的支撑和保障。     

“十四五”期间生态文明建设理念下广州林业和园林发展对策与建议

简述广州林业和园林“十三五”期间的发展成就，通过与国外发达地区和国内发达城市相同指标数据对比，归纳总结广州林业和园林发展现状和存在一些亟需破解的难题。以问题及城市发展建设目标为导向，解读广州“十四五”期间林业和园林高质量发展的六大重要任务，包括打造千年花城新名片，深化绿色资源提质增效，织牢生态安全保护底线，增强居民绿色获得感，筑牢湾区生态安全格局，提升治理能力现代化。     

外源调节剂对番茄幼苗抗冻性的诱导效应

以“金桃”番茄为试材,提前3d叶喷植物生长调节剂14-羟基芸苔素甾醇和SF-花粉多糖植物维生素C,研究了在0℃冻害胁迫下番茄幼苗叶片最大光合效率(QY-max)及抗氧化酶活性的变化,以期为提升番茄抗冻性研究提供参考依据。结果表明:单用或者复配均可有效缓解冻害对植株光合能力的损害,且尤以复配效果最好。抗氧化酶活性检测结果显示,在冻害胁迫下复配可显著提升番茄幼苗中过氧化物酶(POD)和过氧化氢酶(CAT)活性,推测复配可协同增效通过提升抗氧化酶来保护番茄冻害下的光合能力。