谷氨酸棒杆菌代谢工程高效生产L-缬氨酸北大核心CSCD

L-缬氨酸作为一种支链氨基酸,广泛应用于医药和饲料等领域。本研究借助多种代谢工程策略相结合的方法,构建了生产L-缬氨酸的微生物细胞工厂,实现了L-缬氨酸的高效生产。首先,通过增强糖酵解途径、减弱副产物代谢途径相结合的方式,强化了L-缬氨酸合成前体丙酮酸的供给;其次,针对L-缬氨酸合成路径关键酶—乙酰羟酸合酶进行定点突变,提高了菌株的抗反馈抑制能力,并利用启动子工程策略,优化了路径关键酶的基因表达水平;最后,利用辅因子工程策略,改变了乙酰羟酸还原异构酶和支链氨基酸转氨酶的辅因子偏好性,由偏好NADPH转变为偏好NADH,从而提高了L-缬氨酸的合成能力。在5L发酵罐中,最优谷氨酸棒杆菌工程菌株Corynebacterium glutamicum K020的L-缬氨酸产量、得率和生产强度分别达到了110g/L、0.51g/g和2.29 g/(L·h)。     

Rapid Analysis of Four Alkaloids in <i>Uncaria rhynchophylla</i> by Core-Shell Column HPLC and Quantitative Analysis of Multi-Components by Single Marker (QAMS)

As a traditional herbal medicine, the major alkaloids in Uncaria rhynchophylla have been proven to have blood pressure-lowering and sedative effects. It is essential to develop an effective method for the determination of the major alkaloids in U. rhynchophylla. In this research, a rapid quantitative analysis involving multi-components analysis by a single marker strategy coupled with core-shell column HPLC was adopted to analyse four alkaloids (corynoxeine, isocorynoxeine, isorhynchophylline, rhynchophylline) in U. rhynchophylla. Isorhynchophylline was selected as the internal reference substance, the content of which was determined by the traditional external standard method. Relative correction factors (RCF) between isorhynchophylline and the other three alkaloids were calculated respectively. The results showed that the QAMS method had good robustness under different HPLC instruments. Nineteen batches of U. rhynchophylla were tested. No significant difference was observed between the results by QAMS and EMS (Correlation coefficient > 0.99, p > 0.05). The QAMS method could be employed as a rapid, effective technique for the quality control of U. rhynchophylla.     

A Rapid Determination of 30 Prohibited Pesticide Residues in Lycii Fructus by UPLC-MS/MS

Prohibited pesticide residues have become one of the main factors affecting the quality and safety of Lycii Fructus, However, rarely studies focus on the rapid determination of these residues. Here, a total of 30 kinds of prohibited pesticide residues were determined by ultra-performance liquid chromatography tandem triple quadrupole mass spectrometry (UPLC-MS/MS) in five different process ways. Pretreatment methods, chromatographic separation and detection conditions in mass spectrometry were all optimized accordingly. Among the five different pretreatment methods, the first and third solid phase extraction failed to provide high recoveries of sulfosulfuron compounds (both lower than 60%). Recovery of chlorphenamidine by the Quick Easy Cheap Effective Rugged and Safe multiresidue method (QuEChERS) was lower than 60%, which did not meet the requirements of trace determination. The concentrations of 30 prohibited pesticides residues treated by straightforward and solid phase extraction showed good linearity in their corresponding ranges, with correlation coefficients over 0.99. The average recoveries of straightforward ranged from 78.13% to 110.9%, while RSD ranged from 1.3% to 16.9%, albeit poor purification was observed. The recovery yield from solid phase extraction was between 67.75% and 103.08% with RSD value from 0.8% to 14.0%, which met the requirements of trace determination, this method has good precision and stability. These results could be employed to other Traditional Chinese Medicines (TCMs) in detecting prohibited pesticide residues.     

肠道菌群在脊髓损伤后胃肠道炎症反应中的研究进展

脊髓损伤(spinal cord injury, SCI)目前尚无有效的治疗手段。脊髓损伤后,患者常伴有严重的胃肠功能障碍,严重影响患者的生活质量。研究发现,脊髓损伤后肠道菌群的紊乱和脊髓损伤后的胃肠道功能障碍密切相关。因此,本文围绕脊髓损伤后肠道菌群的变化,探讨肠道菌群在迷走神经、下丘脑-垂体-肾上腺和肠道菌群代谢物3个途径中发挥的作用,及与胃肠道炎症反应相关的研究进展。     

非侵入物理疗法——红光照射改善脂多糖诱发小鼠抑郁样行为

目的 抑郁的发生机制不清及药物的临床疗效不佳,导致其成为世界难题。已有研究发现甲醛的气态暴露或液态腹腔注射都可直接诱发小鼠抑郁样行为,而内源甲醛是否参与抑郁的发生尚不清楚。本研究探索脂多糖（lipopolysaccharide,LPS）是否通过刺激内源甲醛产生而诱发小鼠抑郁的分子机制;并观察非侵入物理疗法——630 nm红光照射是否能激活甲醛脱氢酶而降解甲醛,从而改善小鼠抑郁样行为。方法 雄性成年C57BL/6J小鼠随机分组：a.对照组,腹腔注射磷酸缓冲液（phosphate buffer solution,PBS）;b.抑郁模型组,按浓度梯度腹腔注射LPS;c.红光干预组,按浓度梯度腹腔注射LPS后并定时进行630 nm全身红光照射。采用旷场实验（open field test,OFT）、糖水偏爱（suorose preference test,SPT）、悬尾实验（tail suspension test,TST）、强迫游泳（forced swimming test,FST）等方法,评估小鼠的抑郁样行为;用甲醛荧光（Na-FA,特异甲醛荧光探针）定量法及整脑甲醛荧光成像法,检测小鼠脑...     

蜜蜂脑乙酰胆碱免疫反应阳性神经元的分布

通过免疫组织化学方法-PAP法,使用乙酰胆碱(ACh)抗体,研究了中华蜂(Apis sinensis)和意大利蜂(Apis mellifera L)脑中具有乙酰胆碱免疫阳性反应的神经元胞体的形态、分布及神经元类型.并和已知的在其他昆虫脑中用ACh的合成酶ChAT和其水解酶AChE的抗体免疫组化法所获得的结果进行了比较.     

广西北部湾海岸带、海岛的外来入侵植物

为保护广西北部湾海岸带、海岛的植物多样性和生态系统多样性,通过样方、样带法野外实地调查并结合文献资料,对其外来入侵植物的物种组成、原产地、生活型、入侵途径和危害状况等进行了分析。结果表明,广西北部湾海岸带、海岛共有入侵植物64种,隶属28科55属,其中菊科(Asteraceae)最多(15种)。草本植物最多,有48种(75.00%)。原产地来自美洲的植物最多,有49种。入侵风险等级可划分为5个等级,其中Ⅰ级严重危害的有8种(12.50%)。与广西、广东、海南及华南地区的外来入侵植物在物种组成、生活型和原产地等方面呈现出较强的相似性;北部湾与广西中越边境内陆地区来自美洲的入侵植物都超过60%。因此推测广西外来入侵植物有两条可能的入侵线路：一是从海南登录,二是从中越边境跨入。广西北部湾海岸带、海岛的外来入侵植物总数(相对整个广西)虽较少,但其8种Ⅰ级严重危害植物的防治,仍需引起重视。     

固相萃取与气相色谱⁃质谱法联用测定食用植物油和含脂肪食品中氯丙醇酯的方法验证研究

氯丙醇酯是国际上广泛关注的食品加工过程污染物,其水解产物氯丙醇对人体（特别是婴幼儿）危害风险较大。采用固相萃取与气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）联用技术,对食用植物油和含脂食品中的氯丙醇酯[3-氯-1,2-丙二醇脂肪酸酯（简称3-MCPD酯）和2-氯-1,3-丙二醇脂肪酸酯（简称2-MCPD酯）]进行检测。该方法准确度高（3-MCPD酯和2-MCPD酯的平均回收率分别为98.9%和96.5%)、灵敏度高(3-MCPD酯和2-MCPD酯的检出限分别为0.042 mg·kg^-1和0.058 mg·kg^-1)、重现性好(相对标准偏差均低于5%)。76批次监测样品中,3-MCPD酯和2-MCPD酯的含量分别为0.042~4.865 mg·kg^-1(平均值为0.773 mg·kg^-1)和0.058~2.592 mg·kg^-1(平均值为0.469 mg·kg^-1)。经机构间的协同验证和英国FAPAS样的能力验证,2种氯丙醇酯在0.200~3.000 mg·kg^-1范围内线性良好,为进一步研究奠定了基础,同时也为食品加工企业严格控制生产过程建立了一种可行的检测方法。     

Four New C19-Diterpenoid Alkaloids from Aconitum nagarum Stapf

Four new aconitine-type C₁₉-diterpenoid alkaloids, were isolated from the roots of Aconitum nagarum Stapf which were named as nagarutines A–D ( 1–4 ), together with eleven known compounds ( 5–15 ). The structures of the compounds were identified by IR, HR-ESI-MS, 1D and 2D NMR spectra. All compounds were tested for the inhibitory effect on LPS induced NO production in RAW 264.7 macrophages, compound 7 showed moderate anti-inflammatory activity effect and Inhibition rate is about 44.50%.