分类: 生物学 >> 植物学 提交时间: 2017-06-15
摘要: Banana is a tropical fruit widely accepted by people over the world. Its chemical composition is critical for the organoleptic property and nutritional value. In this work, the metabolites change during postharvest senescence was investigated by using NMR spectroscopy. The 1D and 2D NMR spectroscopic information revealed the primary and secondary metabolites in banana fruit, including organic acids, amino acids, carbohydrates and phenolics. Bananas at five senescence stages showed similar chemical profiles, but the levels of the individual compounds varied to a large extent. The principal metabolites responsible for postharvest senescence of banana were valine, alanine, aspartic acid, choline, acetate, glucose, malic acid, gallic acid and dopamine. At stage V, ethanol was present due to the conversion of glucose. Salsolinol was generated due to the conversion of dopamine. This was a characteristic marker for the postharvest senescence of banana fruit.
分类: 生物学 >> 植物学 >> 植物生物化学、植物生物物理学 提交时间: 2016-05-04
摘要: Molecular changes elicited by plants in response to fungal attack and how this affects plantpathogen interaction, including susceptibility or resistance, remain elusive. We studied the dynamics in root metabolism during compatible and incompatible interactions between chickpea and Fusarium oxysporum f. sp. ciceri (Foc), using quantitative label-free proteomics and NMR-based metabolomics. Results demonstrated differential expression of proteins and metabolites upon Foc inoculations in the resistant plants compared with the susceptible ones. Additionally, expression analysis of candidate genes supported the proteomic and metabolic variations in the chickpea roots upon Foc inoculation. In particular, we found that the resistant plants revealed significant increase in the carbon and nitrogen metabolism; generation of reactive oxygen species (ROS), lignification and phytoalexins. The levels of some of the pathogenesis-related proteins were significantly higher upon Foc inoculation in the resistant plant. Interestingly, results also exhibited the crucial role of altered Yang cycle, which contributed in different methylation reactions and unfolded protein response in the chickpea roots against Foc. Overall, the observed modulations in the metabolic flux as outcome of several orchestrated molecular events are determinant of plant's role in chickpeaFoc interactions.
分类: 生物学 >> 生物物理学 提交时间: 2016-05-12
摘要: Radio-frequency coil arrays using dipole antenna technique have been recently applied for ultrahigh field magnetic resonance (MR) imaging to obtain the better signal-noise-ratio (SNR) gain at the deep area of human tissues. However, the unique structure of dipole antennas makes it challenging to achieve sufficient electromagnetic decoupling among the dipole antenna elements. Currently, there is no decoupling methods proposed for dipole antenna arrays in MR imaging. The recently developed magnetic wall (MW) or induced current elimination decoupling technique has demonstrated its feasibility and robustness in designing microstrip transmission line arrays, L/C loop arrays and monopole arrays. In this study, we aim to investigate the possibility and performance of MW decoupling technique in dipole arrays for MR imaging at the ultrahigh field of 7T. To achieve this goal, a two-channel MW decoupled dipole array was designed, constructed and analyzed experimentally through bench test and MR imaging. Electromagnetic isolation between the two dipole elements was improved from about -3.6 dB (without any decoupling treatments) to -16.5 dB by using the MW decoupling method. MR images acquired from a water phantom using the MW decoupled dipole array and the geometry factor maps were measured, calculated and compared with those acquired using the dipole array without decoupling treatments. The MW decoupled dipole array demonstrated well-defined image profiles from each element and had better geometry factor over the array without decoupling treatments. The experimental results indicate that the MW decoupling technique might be a promising solution to reducing the electromagnetic coupling of dipole arrays in ultrahigh field MRI, consequently improving their performance in SNR and parallel imaging.
分类: 生物学 >> 生物工程 提交时间: 2018-08-13 合作期刊: 《中国生物工程杂志》
摘要: 优化并全合成里氏木霉几丁质酶基因,在毕赤酵母中实现分泌表达。产物几丁质酶的蛋白浓度达0.17 mg/mL,最适pH为5.6,最适温度为65 ℃,酶活为0.52 U/mL。该酶在50 ℃及以下较稳定。利用该酶水解低脱乙酰度壳聚糖并对产物的组成及结构进行分析。超高效液相色谱-四极杆飞行时间质谱(Ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry,UPLC-QTOF MS)检测及分析结果显示,酶解产物中包含至少41种聚合度2-18,不同脱乙酰度的壳寡糖组分;核磁共振(Nuclear magnetic resonance,NMR)检测及分析结果显示,产物壳寡糖的还原端主要为N-乙酰氨基葡萄糖,非还原端则同时含有N-乙酰氨基葡萄糖及氨基葡萄糖。相关结果可为壳寡糖的结构与功能关系研究提供参考。
分类: 生物学 >> 生态学 提交时间: 2018-01-05 合作期刊: 《中国生态农业学报》
摘要: 植物根系分泌物的根际代谢组学分析有助于更好的理解土壤根际微域内植物根系与土壤和土壤生物之间化学信号交流的根际过程。本文采用核磁共振氢谱(1H NMR)技术, 对基于土壤培养收集的玉米幼苗的根系土壤沥出液(soil leachate, SL)、根鞘土浸提液(rhizosheath soil, RS)、根系水培液(distilled water cultivation, DWC)内的根系分泌物进行了检测, 并结合多维统计分析对比了不同收集方法以及不同氮肥施用量下玉米幼苗根系分泌物组的不同。结果表明: 三种不同方法收集的玉米幼苗根系分泌物的核磁共振氢谱(1H nuclear magnetic resonance, 1H NMR)谱图轮廓及主要标志物明显不同; 玉米幼苗根系分泌物中的α-葡萄糖、苹果酸、亮氨酸、缬氨酸水平受氮肥施用量影响变化显著。采用1H NMR技术, 结合RS和DWC收集方法进行根际代谢组学分析, 可为根际生态及根际氮素营养研究提供重要理论依据。
分类: 生物学 >> 生物工程 提交时间: 2018-04-19 合作期刊: 《中国生物工程杂志》
摘要: 目的:研究pH调控对发酵法生产环β-1,2-葡聚糖的影响,并对pH调控条件下的环葡聚糖的结构进行解析。方法:以根瘤菌ATCC 1333为研究对象,进行pH调控与不调控的发酵过程分析,并结合乙醇分级沉淀对pH调控后的发酵液中多糖进行分离提纯,经Superose 12层析纯化,利用基质辅助激光解吸电离飞行时间质谱(MALDI-MS)、单糖组成分析、电喷雾串联质谱(ESI-MS),傅里叶红外光谱(FTIR),核磁共振(NMR)手段对葡聚糖进行结构鉴定。结果:提出两阶段pH调控发酵策略,生长期pH控制为7.0,产糖期pH控制为5.5,与自然发酵模式相比,环葡聚糖产量增加了52%,细胞浓度增加了102%,并且发酵颜色不再发生褐化现象,更有利于后续环葡聚糖的分离纯化。并确定pH调控对根瘤菌ATCC 1333发酵生产的葡聚糖的结构并无影响,合成的环葡聚糖是以葡萄糖为单体,通过β-1,2糖苷键连接的环葡聚糖,聚合度从17-22,以19为主的环状葡聚糖,无支链结构。结论:pH调控对于发酵生产环β-1,2-葡聚糖的结构无影响,为环β-1,2-葡聚糖的发酵工艺研究提供理论基础,也为研究β-1,2-葡聚糖提供可靠的糖源。