{{'Search' | translate}}
 

HCl

盐酸

Company: Sigma-Aldrich
Catalog#: 320331
Bio-protocol()
Company-protocol()
Other protocol()

Laminarin Quantification in Microalgae with Enzymes from Marine Microbes
Author:
Date:
2018-04-20
[Abstract]  The marine beta-glucan laminarin is an abundant storage polysaccharide in microalgae. High production rates and rapid digestion by heterotrophic bacteria turn laminarin into an ideal carbon and energy source, and it is therefore a key player in the marine carbon cycle. As a main storage glucan laminarin also plays a central role in the energy metabolism of the microalgae (Percival and Ross, 1951; Myklestad, 1974; Painter, 1983). We take advantage of enzymes that digest laminarin selectively and can thereby quantify only this polysaccharide in environmental samples. These enzymes hydrolyze laminarin into glucose and oligosaccharides, which are measured with a standard reducing sugar assay to obtain the laminarin concentration. Prior to this assay, the three enzymes need to be produced via ... [摘要]  海洋β-葡聚糖昆布多糖是微藻中丰富的储存多糖。高生产率和异养细菌的快速消化将昆布多糖转化为理想的碳源和能源,因此它是海洋碳循环的关键参与者。作为主要的储存葡聚糖昆布多糖也在微藻的能量代谢中发挥核心作用(Percival and Ross,1951; Myklestad,1974; Painter,1983)。我们利用可以选择性消化昆布多糖的酶,从而可以对环境样品中的这种多糖进行定量。这些酶将昆布多糖水解成葡萄糖和寡糖,用标准的还原糖测定法测定得到昆布多糖浓度。在此测定之前,需要通过异源表达和纯化产生三种酶。该测定可用于监测环境微藻中的昆布多糖浓度,其通过过滤从海水中浓缩,或用来自藻类实验室培养物的样品中浓缩。

【背景】海洋多糖在海洋碳循环中起着重要作用,是浮游植物生理学的重要组成部分,但受到严重影响。几十年来,农业食品工业一直使用基于酶分析的即用试剂盒来分析各种不同的多糖(Whitaker,1974)。这些快速,稳健和特异性的基于酶的方法评估源自陆地植物即淀粉的多糖,因为它们广泛用于食品,饲料和其他工业应用中(Brunt等人, ,1998)。然而,海洋多糖的类似测定仍然缺乏。受到使用酶在藻类中进行多糖定量的想法的启发,我们开发了一种基于酶的方法来量化在硅藻和其他微藻中生态相关的β-葡聚糖昆布氨酸,也称为菊科金刚烷。

这种应用的三种糖苷水解酶(GH)来自福尔摩沙(Formosa)。并且它们的特征如下:FbGH30是GH30家族的外切型β-1,6-葡聚糖酶,特别是水解与昆布多糖骨架连接的β-1,6-连接的葡萄糖单体分支;并且FaGH17A和FbGH17A是GH家族17的两种内作用β-1,3-葡聚糖酶,其特异性地作用于β-1,3-连接的昆布多糖主链上(Becker等人,2017年, ...

Identification and Quantification of Secondary Metabolites by LC-MS from Plant-associated Pseudomonas aurantiaca and Pseudomonas chlororaphis
Author:
Date:
2018-01-20
[Abstract]  Increased antibiotic resistance of plants and human pathogens and continuous use of chemical fertilizers has pushed microbiologists to explore new microbial sources as potential antagonists. In this study, eight strains of Pseudomonas aurantiaca and Pseudomonas chlororaphis, have been isolated from different plant sources and screened for their antagonistic and plant growth promoting potential (Shahid et al., 2017). All strains were compared with reference strain PB-St2 and their secondary metabolites were isolated by the use of solvent partitioning and subjected to LC/ESI/MS for confirmation of compounds. The ESI-mass spectra obtained were used to characterize the surfactants ionization behavior and [M + H]+ and [M + Na]+ ions were ... [摘要]  哺乳动物正呼吸道病毒(呼肠孤病毒)利用成孔肽穿透宿主细胞膜。 在病毒进入过程中,这一步对于提供含核心颗粒的基因组至关重要。 该协议描述了用于测量呼肠孤病毒诱导的孔形成的体外测定。

【背景】呼肠孤病毒是无包膜的双链RNA病毒,其由两个同心蛋白质壳组成:内衣壳(核心)和外衣壳(Dryden等人,1993; Zhang等人, / ,2005; Dermody et al ,2013)。在附着之后,病毒颗粒被内吞(Borsa et al。,1979; Ehrlich et al。,2004; Maginnis et al。,2006; Maginnis和宿主组织蛋白酶蛋白酶降解σ3外壳蛋白(Chang和Zweerink,1971; Silverstein等人,1972; Borsa等人,et al。 1981; Sturzenbecker等人,1987; Dermody等人,1993; Baer和Dermody,1997; Ebert等人, 2002年)。这个过程产生一个亚稳中间体,称为感染性亚病毒颗粒(ISVP),其中细胞穿透蛋白μ1被暴露(Dryden等人,1993)。呼肠孤病毒ISVPs进行第二次构象改变以将含有基因组的核心沉积到宿主细胞的细胞质中。被改变的粒子被称为ISVP *(Chandran et al。,2002)。 ISVP-to-ISVP ...

Optogenetic Stimulation and Recording of Primary Cultured Neurons with Spatiotemporal Control
Author:
Date:
2017-06-20
[Abstract]  We studied a network of cortical neurons in culture and developed an innovative optical device to stimulate optogenetically a large neuronal population with both spatial and temporal precision. We first describe how to culture primary neurons expressing channelrhodopsin. We then detail the optogenetic setup based on the workings of a fast Digital Light Processing (DLP) projector. The setup is able to stimulate tens to hundreds neurons with independent trains of light pulses that evoked action potentials with high temporal resolution. During photostimulation, network activity was monitored using patch-clamp recordings of up to 4 neurons. The experiment is ideally suited to study recurrent network dynamics or biological processes such as plasticity or homeostasis in a network of neurons ... [摘要]  我们研究了文化中的皮层神经元网络,并开发了一种创新的光学装置,以空间和时间精确度激发大量神经元。 我们首先描述如何培养表达channelorhodopsin的原代神经元。 然后,我们将根据快速数字光处理(DLP)投影机的工作原理来详细说明光遗传设置。 该设置能够用独立的光脉冲训练数十到数百个神经元,以高时间分辨率诱发动作电位。 在光刺激期间,使用多达4个神经元的膜片钳记录监测网络活动。 该实验非常适合研究复杂的网络动力学或生物过程,如神经元网络中的可塑性或体内平衡,当子群体由其特征(相关性,速率和大小)进行精细控制的不同刺激激活时。
【背景】光致遗传学提供以毫秒精度控制神经元活动的平均值。然而,神经元通常通过同时激活整个群体的光的闪光或通过在整个视野上的时间调制强度的光同时激活(Boyden等人,2005)。然而,存在几种空间调节光并已被用于使谷氨酸不起作用的方法(Nawrot等人,2009)或激活表达神经元的通道视紫质(ChR2)(Guo等人,2009)(用于审查刺激神经元的可用方法具有空间和时间分辨率参见Anselmi等人,2015)。
为了获得刺激的空间控制,第一种可能性是使用激光并将其光束快速移动到不同位置。例如,通过用声光偏转器偏转激光束已经实现了在不同树枝状位置处的谷蛋白解冻(Shoham等人,2005)。只有我们在有限的区域内足够缓慢地调节光强度,这个策略才可能是可行的。或者,可以使用相位或强度的光调制器来实现光的空间图案。基于相位调制的全息技术允许以三维空间精度获得图像,但是可以以仅100Hz的速率显示图案(Papagiakoumou等人,2010)。如果二维图案是足够的,则可以通过将投影仪或阵列的LED放置在样品的共轭平面中来简单地获得强度调制(Farah等人,2007; ...

Comments