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Hydrochloric acid

盐酸(HCl)

Company: Sigma-Aldrich
Catalog#: 258148
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Bacterial Microcolonies in Gel Beads for High-throughput Screening
Author:
Date:
2018-07-05
[Abstract]  High-throughput screening of a DNA library expressed in a bacterial population for identifying potentially rare members displaying a property of interest is a crucial step for success in many experiments such as directed evolution of proteins and synthetic circuits and deep mutational scanning to identify gain- or loss-of-function mutants.

Here, I describe a protocol for high-throughput screening of bacterial (E. coli) microcolonies in gel beads. Single cells are encapsulated into monodisperse water-in-oil emulsion droplets produced with a microfluidic device. The aqueous solution also contains agarose that gelates upon cooling on ice, so that solid gel beads form inside the droplets. During incubation of the emulsion, the cells grow into monoclonal microcolonies ...
[摘要]  在细菌群体中表达的DNA文库的高通量筛选用于鉴定显示感兴趣性质的潜在稀有成员是在许多实验中成功的关键步骤,例如蛋白质和合成回路的定向进化以及用于鉴定增益的深度突变扫描 - 或功能丧失的突变体。

在这里,我描述了一种用于高通量筛选凝胶珠中细菌(大肠杆菌)微菌落的方案。将单细胞包封成用微流体装置产生的单分散油包水乳液液滴。水溶液还含有琼脂糖,其在冰上冷却时凝胶化,从而在液滴内部形成固体凝胶珠。在乳液温育期间,细胞在珠内生长成单克隆微菌落。在从乳液中分离凝胶珠并通过荧光激活细胞分选(FACS)分选后,从凝胶珠中回收细菌,然后准备进行进一步的分选,诱变或分析。为了通过FACS分类,该方案需要荧光读数,例如荧光报告蛋白的表达。测量微小菌落的平均荧光信号降低了高表型细胞间变异性的影响,并且与单细胞分选相比提高了灵敏度。我们应用这种方法在ON和OFF状态下对pBAD启动子文库进行分类(Duarte et al。,2017)。

【背景】荧光激活细胞分选(FACS)具有> 10 7 事件/ h的无与伦比的筛选通量(Davies,2012)。然而,通过FACS根据其荧光分选单个细胞以筛选合成回路的文库(Schaerli和Isalan,2013)经常受到高表型细胞间变异性的阻碍。或者,可以对水凝胶珠中所含的小细胞集落(微集落)进行分类(Weaver ...

Heterologous Expression and Purification of the CRISPR-Cas12a/Cpf1 Protein
Author:
Date:
2018-05-05
[Abstract]  This protocol provides step by step instructions (Figure 1) for heterologous expression of Francisella novicida Cas12a (previously known as Cpf1) in Escherichia coli. It additionally includes a protocol for high-purity purification and briefly describes how activity assays can be performed. These protocols can also be used for purification of other Cas12a homologs and the purified proteins can be used for subsequent genome editing experiments.


Figure 1. Timeline of activities for the heterologous expression and purification of Francisella novicida Cas12a (FnCas12a) from Escherichia coli
[摘要]  该协议提供了分步说明(图1),用于在大肠杆菌中异源表达新西兰弗朗西斯菌弗朗西丝菌Cas12a(以前称为Cpf1)。 它还包括一个高纯度纯化方案,并简要介绍如何进行活性测定。 这些方案也可以用于其他Cas12a同系物的纯化,并且纯化的蛋白质可以用于随后的基因组编辑实验。

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图1.从大肠杆菌 异源表达和纯化<弗朗西斯弗朗西丝菌 Cas12a(FnCas12a)的活动时间表

【背景】原核CRISPR-Cas免疫系统通过使用CRISPR RNA(crRNA)作为外源DNA或RNA的序列特异性靶向的指导来提供针对病毒和质粒的保护(van der Oost等人,2014; Marraffini ,2015)。 1类CRISPR-Cas系统(包含I型,III型和IV型)通常形成多亚基蛋白-cRNA效应复合物,而2类系统(包含II型,V型和VI型)依赖于单个crRNA-引导的效应物核酸酶用于目标干扰(Mohanraju et al。 2016年)。

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Preparation of Amyloid Fibril Networks
Author:
Date:
2018-02-20
[Abstract]  Networks of amyloid nanofibrils fabricated from common globular proteins such as lysozyme and β-lactoglobulin have material properties that mimic the extracellular microenvironment of many cell types. Cells cultured on such amyloid fibril networks show improved attachment, spreading and in the case of mesenchymal stem cells improved differentiation. Here we describe a detailed protocol for fabricating amyloid fibril networks suitable for eukaryotic cell culture applications. [摘要]  结核分枝杆菌(Mtb)已经发展为从其宿主同化脂肪酸。然而,直到最近,还没有可靠的方法来量化宿主细胞感染期间细菌对脂肪酸的摄取。在这里,我们描述了一种新的方法来量化细胞内的杆菌对脂肪酸的摄取。我们用Mtb组成性表达mCherry感染巨噬细胞,然后用Bodipy-palmitate代谢标记它们。在标记步骤之后,我们在蔗糖垫上分离含有Mtb的吞噬体,并用洗涤剂破坏吞噬体。大量洗涤后,通过流式细胞术分析分离的细菌以确定与细菌相关的Bodipy-棕榈酸酯信号的水平。使用液体培养物中脂肪酸摄取缺陷的Mtb突变体菌株,我们确定该突变体在巨噬细胞感染期间同化比野生型菌株少10倍的Bodipy-棕榈酸酯。这种脂肪酸摄取的定量方法可以用于进一步鉴定参与细胞内Mtb和可能的其他细菌的脂质摄取的途径。

【背景】结核分枝杆菌(Mtb)吸收宿主来源的脂质(脂肪酸和胆固醇)的能力使病原体能够在其宿主内存活(Russell等人,2010; Lovewell 等,2016)。在小鼠感染期间和在人肺组织中,通过巨噬细胞内Mtb上调胆固醇和脂肪酸代谢相关基因来支持这个想法(Schnappinger等人,2003; Rachman等人。2006; Rohde等人,2007;Fontán等人,2008; Tailleux等人,2008; Homolka et al。,2010; Rohde et ...

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