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81.
海洋固氮菌和解磷菌的分离鉴定及发酵条件优化 总被引:1,自引:0,他引:1
【目的】从西沙喜盐草根际沉积物中分离纯化得到具有高效固氮能力及解磷能力的菌株。优化其发酵培养条件,研究其制备海洋微生物菌剂的可能性。【方法】从形态学特征、生理生化、16S rDNA及功能基因水平进行鉴定,通过乙炔还原法、钼锑抗显色法检测菌株的固氮酶活性和解磷能力,单因素法和响应面法优化其发酵培养条件,溶血试验和急性毒性实验鉴定菌株的安全性。【结果】结果表明,菌株AZ16属于星箭头菌(Sagittula stellate),革兰氏阴性菌,选择性固氮培养基中菌落呈黄圆形黏稠状,固氮酶活性达34.63 nmol C2H2/(mL·h),最适生长条件为:盐度25‰、pH 7.5、温度33°C、接种量5.0%;菌株XT37为海洋芽孢杆菌(Bacillus sp.),革兰氏阳性菌,选择性固氮培养基中菌落呈深黄色圆形褶皱,植酸酶活性达239.49μg/L,最适合生长条件为:盐度25‰、pH 6.7、温度28°C、接种量5.0%。溶血实验和急性毒性实验证明两株菌属实际无毒级别。【结论】两株菌具有高效的固氮解磷功能,以及抗高盐、强碱等环境的能力,安全无毒,因此有潜力应用于多功能混合微生物菌剂的研制。 相似文献
82.
83.
Zhao ZX Qiao MQ Yin F Shao B Wu BY Wang YY Wang XS Qin X Li S Yu L Chen Q 《Biosensors & bioelectronics》2007,22(12):3021-3027
Hydrophobins are a family of natural self-assembling proteins with high biocompability, which are apt to form strong and ordered assembly onto many kinds of surfaces. These physical-chemical and biological properties make hydrophobins suitable for surface modification and biomolecule immobilization purposes. A class II hydrophobin HFBI was used as enzyme immobilization matrix on platinum electrode to construct amperometric glucose biosensor. Permeability of HFBI self-assembling film was optimized by selecting the proper HFBI concentration for electrode modification, in order to allow H2O2 permeating while prevent interfering compounds accessing. HFBI self-assembly and glucose oxidase (GOx) immobilization was monitored by quartz crystal microbalance (QCM), and characterization of the modified electrode surface was obtained by scanning electron microscope (SEM). The resulting glucose biosensors showed rapid response time within 6 s, limits of detection of 0.09 mM glucose (signal-to-noise ratio = 3), wide linear range from 0.5 to 20 mM, high sensitivity of 4.214 × 10−3 A M−1 cm−2, also well selectivity, reproducibility and lifetime. The all-protein modified biosensor exhibited especially high efficiency of enzyme utilization, producing at most 712 μA responsive current for per unit activity of GOx. This work provided a promising new immobilization matrix with high biocompatibility and adequate electroactivity for further research in biosensing and other surface functionalizing. 相似文献
84.
本实验观察了活性钙调素(CaM)含量和CaM依赖性蛋白激酶Ⅱ(CaMkinaseⅡ)活性在急性低氧(模拟海拔7000m,5h)和常氧对照大鼠脑子组织中的变化。用流式产胞仪(FACS)所测两组动物脑皮层细胞的CaM,平均荧光强度分别为40.0±4.9和46.1±5.8,急性低氧组明显低于常氧对照组(P<0.05);用同位素液闪计数法所测两组动物皮层脑匀浆提取液中CaMkinaseⅡ活性,分别为184.3±8.1和198.8±9.4pmolPi·min-1·mg-1pro,急性低氧组明显低于常氧对照组(P<0.01)。结果提示CaM和CaMkinaseⅡ对低氧较为敏感,急性低氧时中枢神经细胞结构或功能的紊乱可能与活性CaM的含量减少和CaMkinaseⅡ活性能下降有关。 相似文献
85.
Bin Rui Yin Yi Tie Shen Meijuan Zheng Wenwei Zhou Honglin Du Yadong Fan Yongkang Wang Zhengdong Zhang Shengsheng Xu Zhijie Liu Han Wen Xiaoyao Xie 《PloS one》2015,10(6)
NADPH regeneration capacity is attracting growing research attention due to its important role in resisting oxidative stress. Besides, NADPH availability has been regarded as a limiting factor in production of industrially valuable compounds. The central carbon metabolism carries the carbon skeleton flux supporting the operation of NADPH-regenerating enzyme and offers flexibility in coping with NADPH demand for varied intracellular environment. To acquire an insightful understanding of its NADPH regeneration capacity, the elementary mode method was employed to compute all elementary flux modes (EFMs) of a network representative of central carbon metabolism. Based on the metabolic flux distributions of these modes, a cluster analysis of EFMs with high NADPH regeneration rate was conducted using the self-organizing map clustering algorithm. The clustering results were used to study the relationship between the flux of total NADPH regeneration and the flux in each NADPH producing enzyme. The results identified several reaction combinations supporting high NADPH regeneration, which are proven to be feasible in cells via thermodynamic analysis and coincident with a great deal of previous experimental report. Meanwhile, the reaction combinations showed some common characteristics: there were one or two decarboxylation oxidation reactions in the combinations that produced NADPH and the combination constitution included certain gluconeogenesis pathways. These findings suggested cyclization pathways as a powerful way for NADPH regeneration capacity of bacterial central carbon metabolism. 相似文献
86.
New synaptic bouton formation is disrupted by misregulation of microtubule stability in aPKC mutants
The Baz/Par-3-Par-6-aPKC complex is an evolutionarily conserved cassette critical for the development of polarity in epithelial cells, neuroblasts, and oocytes. aPKC is also implicated in long-term synaptic plasticity in mammals and the persistence of memory in flies, suggesting a synaptic function for this cassette. Here we show that at Drosophila glutamatergic synapses, aPKC controls the formation and structure of synapses by regulating microtubule (MT) dynamics. At the presynapse, aPKC regulates the stability of MTs by promoting the association of the MAP1Brelated protein Futsch to MTs. At the postsynapse, aPKC regulates the synaptic cytoskeleton by controlling the extent of Actin-rich and MT-rich areas. In addition, we show that Baz and Par-6 are also expressed at synapses and that their synaptic localization depends on aPKC activity. Our findings establish a novel role for this complex during synapse development and provide a cellular context for understanding the role of aPKC in synaptic plasticity and memory. 相似文献
87.
Russell J. McCulloh Michael P. Koster Dwight E. Yin Tiffany L. Milner Shawn L. Ralston Vanessa L. Hill Brian K. Alverson Eric A. Biondi 《PloS one》2015,10(2)
BackgroundBlood cultures are often recommended for the evaluation of community-acquired pneumonia (CAP). However, institutions vary in their use of blood cultures, and blood cultures have unclear utility in CAP management in hospitalized children.ObjectiveTo identify clinical factors associated with obtaining blood cultures in children hospitalized with CAP, and to estimate the association between blood culture obtainment and hospital length of stay (LOS).MethodsWe performed a multicenter retrospective cohort study of children admitted with a diagnosis of CAP to any of four pediatric hospitals in the United States from January 1, 2011-December 31, 2012. Demographics, medical history, diagnostic testing, and clinical outcomes were abstracted via manual chart review. Multivariable logistic regression evaluated patient and clinical factors for associations with obtaining blood cultures. Propensity score-matched Kaplan-Meier analysis compared patients with and without blood cultures for hospital LOS.ResultsSix hundred fourteen charts met inclusion criteria; 390 children had blood cultures obtained. Of children with blood cultures, six (1.5%) were positive for a pathogen and nine (2.3%) grew a contaminant. Factors associated with blood culture obtainment included presenting with symptoms of systemic inflammatory response syndrome (OR 1.78, 95% CI 1.10–2.89), receiving intravenous hydration (OR 3.94, 95% CI 3.22–4.83), receiving antibiotics before admission (OR 1.49, 95% CI 1.17–1.89), hospital admission from the ED (OR 1.65, 95% CI 1.05–2.60), and having health insurance (OR 0.42, 95% CI 0.30–0.60). In propensity score-matched analysis, patients with blood cultures had median 0.8 days longer LOS (2.0 vs 1.2 days, P < .0001) without increased odds of readmission (OR 0.94, 95% CI 0.45–1.97) or death (P = .25).ConclusionsObtaining blood cultures in children hospitalized with CAP rarely identifies a causative pathogen and is associated with increased LOS. Our results highlight the need to refine the role of obtaining blood cultures in children hospitalized with CAP. 相似文献
88.
H Z Yin A Nalbandian C-I Hsu S Li K J Llewellyn T Mozaffar V E Kimonis J H Weiss 《Cell death & disease》2012,3(8):e374
Pathological features of amyotrophic lateral sclerosis (ALS) include, in addition to selective motor neuron (MN) degeneration, the occurrence of protein aggregates, mitochondrial dysfunction and astrogliosis. SOD1 mutations cause rare familial forms of ALS and have provided the most widely studied animal models. Relatively recent studies implicating another protein, TDP-43, in familial and sporadic forms of ALS have led to the development of new animal models. More recently, mutations in the valosin-containing protein (VCP) gene linked to the human genetic disease, Inclusion Body Myopathy associated with Paget''s disease of bone and frontotemporal dementia (IBMPFD), were found also to be associated with ALS in some patients. A heterozygous knock-in VCP mouse model of IBMPFD (VCPR155H/+) exhibited muscle, bone and brain pathology characteristic of the human disease. We have undertaken studies of spinal cord pathology in VCPR155H/+ mice and find age-dependent degeneration of ventral horn MNs, TDP-43-positive cytosolic inclusions, mitochondrial aggregation and progressive astrogliosis. Aged animals (∼24–27 months) show electromyography evidence of denervation consistent with the observed MN loss. Although these animals do not develop rapidly progressive fatal ALS-like disease during their lifespans, they recapitulate key pathological features of both human disease and other animal models of ALS, and may provide a valuable new model for studying events preceding onset of catastrophic disease. 相似文献
89.
溶氧及pH对产朊假丝酵母分批发酵生产谷胱甘肽的影响 总被引:16,自引:0,他引:16
在7 L发酵罐中研究了溶氧和pH对产朊假丝酵母分批发酵生产谷胱甘肽的影响。结果表明,当葡萄糖浓度为30 g/L且通气量控制在5 L/min时,搅拌转速达到300 r/min即可满足细胞生长和谷胱甘肽合成对溶解氧的需求。不同pH控制方式对谷胱甘肽分批发酵的影响有较大差异。不控制pH时,细胞干重和谷胱甘肽产量比控制pH为55的发酵分别低27%和95%,且有50%的谷胱甘肽向胞外渗漏。研究了将pH控制在4.0、4.5、5.0、5.5、6.0和6.5的谷胱甘肽分批发酵过程,发现在pH 5.5时谷胱甘肽总产量最高。用前期研究建立的动力学模型模拟了不同pH (4.0~6.5)下的分批发酵过程,并从动力学角度解释了pH对细胞生长和谷胱甘肽合成的影响。 相似文献
90.
昆虫表达系统是一类应用广泛的真核表达系统,该系统具有与其他高等真核表达系统相似的翻译后修饰、加工及转移外源蛋白的能力。本文介绍了昆虫表达系统的构建过程,并以基因工程抗体为主讨论了外源蛋白在昆虫表达体系中的表达特征。 相似文献