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Reducing Agents: Materials that add an electron to an element or compound, that is, decrease the positiveness of its valence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)

Stomata Tape-Peel: An Improved Method for Guard Cell Sample Preparation

1Plant Molecular and Cellular Biology Program, University of Florida, 2Department of Biology, University of Florida, 3Genetics Institute (UFGI), University of Florida, 4Alkali Soil Natural Environmental Science Center, Northeast Forestry University, 5Interdisciplinary Center for Biotechnology Research (ICBR), University of Florida

JoVE 57422


 Biology

Application of Elemental Lanthanides in the Selective C-F Activation of Trifluoromethylated Benzofulvenes Providing Access to Various Difluoroalkenes

1Institut de Chimie Moléculaire de Reims UMR 7312, Université de Reims Champagne Ardenne, 2Institut Charles Gerhardt Montpellier UMR 5253, Ecole Nationale Supérieure de Chimie de Montpellier

JoVE 57948


 Chemistry

Synthesis of Multi-walled Carbon Nanotubes Modified with Silver Nanoparticles and Evaluation of Their Antibacterial Activities and Cytotoxic Properties

1Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science and Technology, 2School of Integrative Engineering, Chung-Ang University, 3Division of Synthetic Biology and Regenerative Medicine, Institute for Quantitative Health Science and Engineering, Michigan State University

JoVE 57384


 Bioengineering

Separating Protein with SDS-PAGE

JoVE 5058

Sodium Dodecyl Sulfate Poly-Acrylamide Gel Electrophoresis, or SDS-PAGE, is a widely-used technique for separating mixtures of proteins based on their size and nothing else. SDS, an anionic detergent, is used to produce an even charge across the length of proteins that have been linearized. By first loading them into a gel made of polyacrylamide and then applying an electric field to the gel, SDS-coated proteins are then separated. The electric field acts as the driving force, drawing the SDS coated proteins towards the anode with larger proteins moving more slowly than small proteins. In order to identify proteins by size, protein standards of a known size are loaded along with samples and run under the same conditions. This video presents an introduction to SDS-PAGE by first explaining the theory behind it and later demonstrating its step-by-step procedure. Various experimental parameters, such as the polyacrylamide concentration and voltage applied to the gel are discussed. Downstream staining methods like Coomassie and silver stains are introduced, and variations of the method, like 2D gel electrophoresis are presented.


 Basic Methods in Cellular and Molecular Biology

Cell-surface Biotinylation Assay

JoVE 5647

A cell can regulate the amount of particular proteins on its cell membrane through endocytosis, following which cell surface proteins are effectively sequestered in the cytoplasm. Once within a cell, these surface proteins can be either destroyed or “recycled” back to the membrane. The cell surface biotinylation assay provides researchers with a way to study these phenomena. The technique makes use of a derivative of the small molecule biotin, which can label surface proteins and then be chemically cleaved. However, if the surface protein is endocytosed, the biotin derivative will be protected from cleavage. Thus, by analyzing the uncleaved, endocytosed biotin label, scientists can assess the amounts of internalized surface proteins.In this video, we review the concepts behind the biotinylation assay, delving into the chemical structure of the biotin derivative and the mechanism of its cleavage. This is followed by a generalized protocol of the technique, and finally, a description of how researchers are currently using it to study the dynamics of different cell surface proteins.


 Cell Biology

Two-Dimensional Gel Electrophoresis

JoVE 5686

Two-dimensional gel electrophoresis (2DGE) is a technique that can resolve thousands of biomolecules from a mixture. This technique involves two distinct separation methods that have been coupled together: isoelectric focusing (IEF) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). This physically separates compounds across two axes of a gel by their isoelectric points (an electrochemical property) and their molecular weights. The procedure in this video covers the main concepts of 2DGE and a general procedure for characterizing the composition of a complex protein solution. Three examples of this technique are shown in the applications section, including biomarker detection for disease initiation and progress, monitoring treatment in patients, and the study of proteins following posttranslational modification (PTM). Two-dimensional, or 2D, gel electrophoresis is a technique utilizing two distinct separation methods which can separate thousands of proteins from a single mixture. One of the techniques, SDS-PAGE or sodium dodecyl sulfate polyacrylamide gel electrophoresis, cannot fully separate complex mixtures alone. 2D gel electrophoresis couples the SDS-PAGE to a second method, isoelectric focusing or IEF, which separates based on isoelectric points, allowing for the resolution of potentially a


 Biochemistry

Reducing Agents

JoVE 10354

Source: Vy M. Dong and Daniel Kim, Department of Chemistry, University of California, Irvine, CA

Controlling the reactivity and selectivity during the synthesis of a molecule is very important criteria for chemists. This has led to the development of many reagents that allow chemists to pick and choose reagents suitable for a given task. Quite often, a balance between reactivity and selectivity needs to be achieved. This experiment will use IR spectroscopy to monitor the reaction and to understand the reactivity of carbonyl compounds as well as the reactivity of hydride-reducing reagents.


 Organic Chemistry II

Chemical Storage: Categories, Hazards And Compatibilities

JoVE 10380

Source: Robert M. Rioux & Taslima A. Zaman, Pennsylvania State University, University Park, PA

While the use of various chemicals in experimental research is essential, it is also important to safely store and maintain them as a part of the Environmental, Health and Safety (EHS) program. The properties of chemicals and their reactivity vary broadly and if chemicals are not managed, stored, and labeled properly, they can have harmful or even destructive consequences such as toxic fume production, fire or explosion, which may result in human fatality, property damage or environmental hazards. Therefore, an appropriate chemical label should identify the material and list the associated hazards, and users should have knowledge of how to read chemical labels and safety data sheets (SDS). Proper chemical storage must meet OSHA (Occupational Safety and Health Association) standards and this can prevent most chemical reactivity hazards.


 Lab Safety

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