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Cell Polarity: Orientation of intracellular structures especially with respect to the apical and basolateral domains of the plasma membrane. Polarized cells must direct proteins from the Golgi apparatus to the appropriate domain since tight junctions prevent proteins from diffusing between the two domains.

The C. elegans Intestine As a Model for Intercellular Lumen Morphogenesis and In Vivo Polarized Membrane Biogenesis at the Single-cell Level: Labeling by Antibody Staining, RNAi Loss-of-function Analysis and Imaging

1Mucosal Immunology and Biology Research Center, Developmental Biology and Genetics Core, Massachusetts General Hospital, Harvard Medical School, 2College of Life Sciences, Jilin University, 3Faculty of Health Sciences, University of Macau

JoVE 56100

 Developmental Biology

Nucleophilic Substitution

JoVE 10465

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

Nucleophilic substitution reactions are among the most fundamental topics covered in organic chemistry. A nucleophilic substitution reaction is one where a nucleophile (electron-rich Lewis base) replaces a leaving group from a carbon atom.

SN1 (S = Substitution, N = Nucleophilic, 1 = first-order kinetics) SN2 (S = Substitution, N = Nucleophilic, 2 = second-order kinetics) This video will help to visualize the subtle differences between an SN1 and SN2 reaction and what factors help to speed up each type of nucleophilic substitution reaction. The first section will focus on reactions that will help to better understand and learn about nucleophilic substitution reactions. The second section will focus on a real-world example of a substitution reaction.

 Organic Chemistry II

Monitoring Changes in Membrane Polarity, Membrane Integrity, and Intracellular Ion Concentrations in Streptococcus pneumoniae Using Fluorescent Dyes

1Department of Microbiology and Immunology, University at Buffalo, State University of New York, 2Witebsky Center for Microbial Pathogenesis and Immunology, University at Buffalo, State University of New York, 3New York State Center of Excellence in Bioinformatics and Life Sciences, University at Buffalo, State University of New York

JoVE 51008

 Immunology and Infection

How to Study Basement Membrane Stiffness as a Biophysical Trigger in Prostate Cancer and Other Age-related Pathologies or Metabolic Diseases

1Departamento de Genética, Facultad de Medicina, Universidad de la República (UDELAR), 2Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, 3School of Biological, Biomedical & Environmental Sciences, University of Hull

JoVE 54230

 Cancer Research

Flat Mount Imaging of Mouse Skin and Its Application to the Analysis of Hair Follicle Patterning and Sensory Axon Morphology

1Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, 2Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, 3Department of Ophthalmology, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine

JoVE 51749


Human Dupuytren's Ex Vivo Culture for the Study of Myofibroblasts and Extracellular Matrix Interactions

1Department of Molecular Cell Biology, Cancer Genomics Centre and Centre for Biomedical Genetics, Leiden University Medical Center, 2Department of Orthopedic Surgery, Academic Medical Center, 3Department of Plastic, Reconstructive and Hand Surgery, Academic Medical Center, 4Department of Orthopedic Surgery, Mayo Clinic, 5Department of Biochemistry and Molecular Biology, Mayo Clinic, 6Department of Dermatology, Leiden University Medical Center

JoVE 52534


Recording Temperature-induced Neuronal Activity through Monitoring Calcium Changes in the Olfactory Bulb of Xenopus laevis

1Institute of Neurophysiology and Cellular Biophysics, Georg-August-Universität Göttingen, 2Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Georg-August-Universität Göttingen, 3DFG Excellence Cluster 171, Georg-August-Universität Göttingen, 4German Hearing Center Hannover

JoVE 54108


High-Performance Liquid Chromatography (HPLC)

JoVE 10156

Source: Dr. Paul Bower - Purdue University

High-performance liquid chromatography (HPLC) is an important analytical method commonly used to separate and quantify components of liquid samples. In this technique, a solution (first phase) is pumped through a column that contains a packing of small porous particles with a second phase bound to the surface. The different solubilities of the sample components in the two phases cause the components to move through the column with different average velocities, thus creating a separation of these components. The pumped solution is called the mobile phase, while the phase in the column is called the stationary phase. There are several modes of liquid chromatography, depending upon the type of stationary and/or mobile phase employed. This experiment uses reversed-phase chromatography, where the stationary phase is non-polar, and the mobile phase is polar. The stationary phase to be employed is C18 hydrocarbon groups bonded to 3-µm silica particles, while the mobile phase is an aqueous buffer with a polar organic modifier (acetonitrile) added to vary its eluting strength. In this form, the silica can be used for samples that are water-soluble, providing a broad range of applications. In this experiment, the mixtures of three components frequently found

 Analytical Chemistry

Sonication Extraction of Lipid Biomarkers from Sediment

JoVE 10055

Source: Laboratory of Jeff Salacup - University of Massachusetts Amherst

The material comprising the living "organic" share of any ecosystem (leaves, fungi, bark, tissue; Figure 1) differs fundamentally from the material of the non-living "inorganic" share (rocks and their constituent minerals, oxygen, water, metals). Organic material contains carbon linked to a series of other carbon and hydrogen molecules (Figure 2), which distinguishes it from inorganic material. Carbon's wide valency range (-4 to +4) allows it to form up to four separate covalent bonds with neighboring atoms, usually C, H, O, N, S, and P. It can also share up to three covalent bonds with a single other atom, such as the triple bond in the often-poisonous cyanide, or nitrile, group. Over the past 4.6 billion years, this flexibility has led to an amazing array of chemical structures, which vary in size, complexity, polarity, shape, and function. The scientific field of organic geochemistry is concerned with the identification and characterization of the whole range of detectable organic compounds, called biomarkers, produced by life on this planet, as we

 Earth Science

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