环渤海滨海湿地鸻鹬类水鸟多样性及其环境影响因子

环渤海湿地是水鸟南北迁徙的重要驿站,尤其对于该线路上的鸻鹬鸟类具有非常重要的意义。以环渤海地区12处典型滨海湿地为研究对象,于2016-2020年每年春季开展水鸟调查,明确了鸻鹬类水鸟群落组成及其时空变化,采用结构方程模型 （Structural Equation Modeling,SEM）分析了鸻鹬类水鸟多样性与环境因子的响应关系,评估了各环境因子的影响强度。结果表明：（1）共记录到鸻鹬类水鸟7科51种,几乎全部为旅鸟。全球极危物种1种,濒危物种3种,近危物种9种。国家一级保护鸟类2种,国家二级保护鸟类8种。黑腹滨鹬（Calidris alpina）、大滨鹬（Calidris tenuirostris）、黑尾塍鹬（Limosa limosa）、灰鸻（Pluvialis squatarola）、斑尾塍鹬（Limosa lapponica）个体数量最多。（2）山东黄河三角洲、辽宁辽河口、天津北大港等河口湿地,水鸟种类多,单位面积水鸟数量较少。（3）河北沧州沿海、山东滨州贝壳堤岛及其周边区域为环渤海地区湿地集中区,水鸟种类较多。（4）综合影响强度为保护强度>食物>气候,建立自然保护地是保护水鸟多样性的最有效措施。（5）建议将河北南大港湿地和鸟类省级自然保护区提升至国家级,扩大滨州贝壳堤岛与湿地国家级自然保护区面积,对山东黄河三角洲、辽宁辽河口覆盖的各级各类自然保护地进行优化整合。研究结果能为环渤海地区鸻鹬类水鸟保护策略的制定提供相关依据。     

普通烟草NtODB基因的电子克隆、表达及生物信息学分析

ODB基因在植物同源重组依赖性的DNA双键断裂修复过程中起重要作用,对植物诱变育种具有潜在的应用价值。克隆烟草NtODB基因并分析其表达特征为丰富ODB基因在同源重组DNA修复过程中的作用提供证据。为得到烟草NtODB基因序列,采用电子克隆技术获得该基因cDNA序列并克隆验证。进一步使用生物信息学方法分析该基因表达特征,对预测蛋白的理化性质、信号肽、高级结构等进行预测。生物信息学分析结果表明,NtODB基因开放阅读框包含579个碱基,蛋白含192个氨基酸残基,NtODB蛋白具有碱性和亲水性,主要定位于细胞质内;实时荧光定量PCR检测结果显示NtODB基因在不同组织中呈现组成型表达特征;亚细胞定位检测提示NtODB主要表达于细胞膜和叶绿体。NtODB基因的克隆与表达分析及其蛋白高级结构和理化性质的预测,可为进一步丰富ODB基因在同源重组依赖的DNA修复系统中的作用机制提供证据。     

“共轭聚合物-产电菌”复合生物电极构建及其在微生物燃料电池中的应用

微生物燃料电池(Microbial fuel cell,MFC)作为一种生物电化学装置,在可再生能源生产和废水处理方面的巨大潜力已引起广泛关注。然而MFC面临输出功率低、欧姆内阻高以及启动时间长等问题,极大限制了其在实际工程中的应用。MFC中阳极是微生物附着的载体,对电子的产生及传递起着关键作用,开发优质的生物电极已发展成为改善MFC性能的有效途径。共轭聚合物具有成本低、电导率高、化学稳定性及生物相容性好等优点,利用共轭聚合物修饰生物电极结构,可以实现大比表面积、缩短电荷转移路径,从而实现高效生物电化学性能。同时,纳米级共轭聚合物包覆细菌,可以使细菌产生的电子有效地传递到电极。文中综述了最近报道的共轭聚合物在MFC中的应用,重点介绍了共轭聚合物修饰的MFC阳极,系统分析了共轭聚合物的优点及局限性,以及这些高效复合生物电极如何解决MFC应用中存在的低输出功率、高欧姆内阻及长启动时间等问题。     

重组小麦静息巯基氧化酶的表达、酶学特性及其对面包品质的影响

为发展新型面粉改良酶制剂,利用大肠杆菌Escherichia coli原核表达了小麦静息巯基氧化酶(Wheat quiescin sulfhydryl oxidase,wQSOX)。将合成的wqsox基因构建至pMAL-c5x载体,并在大肠杆菌中进行表达,优化蛋白表达条件后对重组蛋白进行分离纯化及融合标签切除,获得的重组wQSOX蛋白用于酶学性质探究以及面包品质改良。结果表明,合成的截短wqsox基因包含1359 bp,编码453个氨基酸,理论蛋白分子量51 kDa;构建的pMAL-c5x-wqsox重组质粒在E.coli Rosetta gamiB(DE3)中可溶表达了重组蛋白MBP-wQSOX,其最佳表达条件为:诱导温度25℃,诱导剂IPTG浓度0.3 mmol/L,诱导时间6 h;利用Xa因子蛋白酶切除了MBP融合标签,亲和层析纯化得到了wQSOX;wQSOX可催化DTT、GSH和Cys氧化,并伴随着H2O2的生成,其中对DTT表现出最高的底物特异性;酶学性质研究发现,wQSOX最适反应温度和pH分别为50℃和10.0,在高温和碱性环境条件下表现出较好的稳定性;每克面粉中添加1.1 U wQSOX能够显著(P<0.05)提高26.4%的面包比容,降低20.5%的面包芯硬度和24.8%的咀嚼性,表现出了较好的改良面包加工品质能力。研究结果对丰富新型面粉改良酶制剂种类以及推动wQSOX在焙烤行业的应用奠定了理论基础。     

ENaC and ROMK channels in the connecting tubule regulate renal K+ secretion

We measured the activities of epithelial Na channels (ENaC) and ROMK channels in the distal nephron of the mouse kidney and assessed their role in the process of K⁺ secretion under different physiological conditions. Under basal dietary conditions (0.5% K), ENaC activity, measured as amiloride-sensitive currents, was high in cells at the distal end of the distal convoluted tubule (DCT) and proximal end of the connecting tubule (CNT), a region we call the early CNT (CNTe). In more distal parts of the CNT (aldosterone-sensitive portion [CNTas]), these currents were minimal. This functional difference correlated with alterations in the intracellular location of ENaC, which was at or near the apical membrane in CNTe and more cytoplasmic in the CNTas. ROMK activity, measured as TPNQ-sensitive currents, was substantial in both segments. A mathematical model of the rat nephron suggested that K⁺ secretion by the CNTe predicted from these currents provides much of the urinary K⁺ required for K balance on this diet. In animals fed a K-deficient diet (0.1% K), both ENaC and ROMK currents in the CNTe decreased by ∼50%, predicting a 50% decline in K⁺ secretion. Enhanced reabsorption by a separate mechanism is required to avoid excessive urinary K⁺ losses. In animals fed a diet supplemented with 3% K, ENaC currents increased modestly in the CNTe but strongly in the CNTas, while ROMK currents tripled in both segments. The enhanced secretion of K⁺ by the CNTe and the recruitment of secretion by the CNTas account for the additional transport required for K balance. Therefore, adaptation to increased K⁺ intake involves the extension of robust K⁺ secretion to more distal parts of the nephron.     

基于AFM的活体状态外泌体纳米结构及机械特性研究

外泌体在细胞生理病理活动过程中起着重要的调控作用,研究外泌体的行为特性对于揭示生命活动及疾病发生发展的内在机理具有重要的基础意义.然而由于缺乏合适的观测手段及方法,目前对于活体状态下外泌体结构及特性的认知仍然很不足.原子力显微镜(AFM)的发明为研究溶液环境下天然状态生物样本提供了强大的技术工具,已成为生物学重要研究手段.本文利用AFM对单个活体状态外泌体的纳米结构及机械特性进行了研究.通过多聚赖氨酸静电吸附作用将从淋巴瘤患者骨髓中分离的外泌体吸附至基底,在溶液环境下实现了对单个活体状态外泌体的高质量AFM形貌成像并通过与空气中成像结果进行对比揭示了空气干燥处理对外泌体形貌的影响.在此基础上,分别利用AFM压痕试验和多参数成像技术实现了对单个活体状态外泌体机械特性的定量测量和可视化表征.最后基于所建立的方法技术揭示了化学处理后外泌体结构和机械特性的动态变化.研究结果为研究纳米尺度下活体状态外泌体的结构及特性,以更好理解天然状态外泌体的生理行为提供了新的方法和思路,对于外泌体研究具有潜在积极的意义.     

Effects of growth-promoting rhizobacteria on maize growth and rhizosphere microbial community under conservation tillage in Northeast China

Conservation tillage in conjunction with straw mulching is a sustainable agricultural approach. However, straw mulching reduces the soil temperature, inhibits early maize growth and reduces grain yield in cold regions. To address this problem, we investigated the effects of inoculation of plant growth-promoting rhizobacteria (PGPR) on maize growth and rhizosphere microbial communities under conservation tillage in Northeast China. The PGPR strains Sinorhizobium sp. A15, Bacillus sp. A28, Sphingomonas sp. A55 and Enterobacter sp. P24 were isolated from the maize rhizosphere in the same area and inoculated separately. Inoculation of these strains significantly enhanced maize growth, and the strains A15, A28 and A55 significantly increased grain yield by as much as 22%–29%. Real-time quantitative PCR and high-throughput sequencing showed that separate inoculation with the four strains increased the abundance and species richness of bacteria in the maize rhizosphere. Notably, the relative abundance of Acidobacteria_Subgroup_6, Chloroflexi_KD4-96, and Verrucomicrobiae at the class level and Mucilaginibacter at the genus level were positively correlated with maize biomass and yield. Inoculation with PGPR shows potential for improvement of maize production under conservation tillage in cold regions by regulating the rhizosphere bacterial community structure and by direct stimulation of plant growth.