生物化学技术

DNA methyltransferase 1 (DNMT1) is the enzyme responsible for the maintenance of DNA methylation patterns during cell division. DNMT1 expression is tightly regulated within the cell cycle. Our previous study showed that the binding of a protein with an apparent size of ∼40 kDa on DNMT1 3′-UTR tr ...

Calcitriol (1α, 25-dihydroxyvitamin D3) induces the expression of CD14 in mononuclear phagocytes. The mechanisms accounting for this have been unclear since the promoter of CD14 does not contain a canonical vitamin D response element (VDRE). Calcitriol has been shown to regulate the act ...

Acetyl phosphate (acetyl-P) serves critical roles in coenzyme A recycling and ATP synthesis. It is the intermediate of the Pta-AckA pathway that inter-converts acetyl-coenzyme A and acetate. Acetyl-P also can act as a global signal by donating its phosphoryl group to specific two-compone ...

Drosophila activates a robust defense response to gram-negative bacteria through the Immune deficiency (Imd) pathway. Imd signaling proceeds through c-Jun N-terminal Kinase (JNK), NF-kB and caspase modules. The individual signaling modules act in a highly coordinated manner to yi ...

Freeze-fracture electron microscopy is a technique for examining the ultrastructure of rapidly frozen biological samples by transmission electron microscopy. Of a range of approaches to freeze-fracture cytochemistry that have been developed and tried the most successful is t ...

Activation of lymphocytes in mammals is often quantified by measuring the amount of proliferation during the expansion phase of an immune response. Bromodeoxyuridine (BrdU) incorporation and carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution assays are some ...

Microbes frequently live within multicellular, solid surface-attached assemblages termed biofilms. These microbial communities have architectural features that contribute to population heterogeneity and consequently to emergent cell functions. Therefore, thr ...

相关专题 纸层析分离中影响迁移率的因素有样品物质结构、样品分子极性、滤纸、层析溶剂、PH值、温度、展开方式和样品溶液中杂质等。 一、样品物质结构和分子极性： 样品物质结构和分子极性是影响迁移率的主要因素。 二、滤纸： 不同滤纸的厚薄和纤维松紧度各不相同，结合的水量不一样。 滤纸上所含的杂质影响迁移率，必要时要进行预处理。 三、层析溶剂： 同一物质在不同的溶剂系统中进行层析分离时迁移率不同。溶剂系统中的试剂若纯度不够，需用离心机进行预处理。 四、PH值： 溶剂 ...

相关专题 薄层层析（TLC）技术 一、薄层层析分离中的显色： 薄层层析分离中的薄层板展开后，从展开装置中取出，放入干燥器中干燥，然后根据被分离物质的种类和性质，选用相应的显色剂显色或用紫外光检测被分离物质的斑点，测量和计算各斑点的迁移率。 样品所含溶质较多或某些组分在单相薄层层析分离中的迁移率比较接近，不易明显分离时，可采用双相薄层层析分离。双相薄层层析分离是将滤纸用一种溶剂展开后吹干，将滤纸转动90度后再用另一种溶剂展开，待 ...

相关专题 一、聚酰胺薄层层析分离原理： 用于薄层层析分离的聚酰胺基团有两类：锦纶66(尼龙)和锦纶6，这两类材料中都含有大量的酰胺基团，故统称为聚酰胺。聚酰胺以其-CO-或-NH-与极性化合物的-OH或=O之间形成氢键，从而发生吸附作用。不同物质与聚酰胺之间形成氢键的能力不同。在聚酰胺薄膜上做层析分离时，流动相从薄膜表面流过，被分离物质在溶剂和薄膜之间按分配系数的大小发生不同速率的吸附与解吸过程，从而使混合物得到有序的分离。 ...

相关专题 一、生物分子的溶剂提取法原理：利用溶剂的溶解作用把所需物质从细胞中转移出来。 二、影响生物分子的溶剂提取效率的因素： 1、溶剂的性质：根据相似相溶原理。 2、离子强度：离子强度是影响物质溶解度的主要因素，但离子强度对不同物质溶解度的影响不同，如高离子强度下DNA-核蛋白溶解度增加，低离子强度下rna-核蛋白溶解度增加，绝大多数蛋白质和酶在稀盐溶液中溶解度增加(盐溶)。 3、PH值：溶剂的PH值影响溶质分子的解离状态，离子状态的物 ...

相关专题 薄层层析（TLC）技术 薄层层析分离中的薄层板制作是指把固定相支持剂均匀地涂布在玻璃板上形成薄层。玻璃板要求表面平滑、清洁，大小按需要选定。 一、干板制作： 干板是将不加粘合剂的支持剂干粉均匀地涂布在玻璃板上制成的薄层板。干板制作简单，展开快，但极易吹散。制作方法如下： 1、选直径约为50mm的玻璃管一根，根据薄层的厚度(一般为0.4～1mm)在其两端绕胶布数圈。 2、将支持剂干粉倒在玻板一端，固定玻璃板一端以防玻璃管推进时移动。 3、把 ...

相关专题 薄层层析（TLC）技术 薄层层析分离中的点样是将经离心机处理后的样品点在薄层的特定部位，点样的好坏直接影响分离效果。点样可用玻璃毛细管或微量移液管等。 一、点样位置： 1、上行展开法点样一般在距薄层下端4～5cm处。 2、下行展开法点样一般在距薄层上端6～8cm处。 3、双向展开法点样处应位于距薄层右侧边5cm与距底边5cm直线的交点。 二、点样注意事项： 1、样品最好用具有挥发性的有机溶剂溶解，不应用水溶液，因为水分子与吸附剂的相互作用 ...

相关专题 一、层析分离技术原理： 层析分离技术是利用混合物中各组份物理化学性质的差别(如分子吸引力、分子亲和力、分子形状、分子大小、分子极性和分配系数等)，使各组分以不同的分配比例分布在固定相和流动相中，从而达到分离目的。层析分离技术常与离心机分离技术结合使用。 二、层析分离技术发展历程： 1903年利用层析分离技术分离植物色素，分离后的叶绿素和叶黄素等在碳酸钙的吸附柱上从上到下排列成色谱，故层析分离又称为色层分离。 1931年利用 ...

Quantitative real-time PCR (qPCR) is a commonly used validation tool for confirming gene expression results obtained from microarray analysis; however, microarray and qPCR data often result in disagreement. The current study assesses factors contributing to the correlation be ...

How the power required for bird flight varies as a function of forward speed can be used to predict the flight style and behavioral strategy of a bird for feeding and migration. A U-shaped curve was observed between the power and flight velocity in many birds, which is consistent to the theoretical predi ...

This paper was originally published in Biological Procedures Online (BPO) on March 23, 2006. It was brought to the attention of the journal and authors that reference 74 was incorrect. The original citation for reference 74, “Stanford V. Biosignals offer potential for direct interfaces and he ...

In this work we describe protocols for the generation of gene deletions and gene replacements using a temperature sensitive plasmid in Escherichia coli O157:H7. This technology requires flanking DNA to be cloned into a temperature sensitive vector but the resulting clone allows great fl ...

The purpose of this manuscript is to discuss fluorogenic real-time quantitative polymerase chain reaction (qPCR) inhibition and to introduce/define a novel Microsoft Excel-based file system which provides a way to detect and avoid inhibition, and enables investigators to consis ...

Protein-protein interactions are required for many viral and cellular functions and are potential targets for novel therapies. Here we detail a series of genetic and biochemical techniques used in combination to find an essential molecular contact point on the duck hepatitis B virus pol ...