Biological Assay:
A method of measuring the effects of a biologically active substance using an intermediate in vivo or in vitro tissue or cell model under controlled conditions. It includes virulence studies in animal fetuses in utero, mouse convulsion bioassay of insulin, quantitation of tumor-initiator systems in mouse skin, calculation of potentiating effects of a hormonal factor in an isolated strip of contracting stomach muscle, etc.
JoVE General
Isolation of Native Soil Microorganisms with Potential for Breaking Down Biodegradable Plastic Mulch Films Used in Agriculture
1Biology Department, Western Washington University, 2Washington State University Northwestern Research and Extension Center, 3Department of Plant and Soil Science, Texas Tech University
Plastic films labeled "biodegradable" are commercially available for agricultural use as mulches. Tillage represents an attractive disposal method, but degradation under field conditions is poorly understood. The purpose of this study was to develop methods for isolating native soil fungi and bacteria that colonize plastic mulch films after field burial.
JoVE General
Bioassays for Monitoring Insecticide Resistance
1Division of Plant Sciences, University of Missouri, Delta Research Center, 2Department of Entomology, Louisiana State University Agricultural Center
This manuscript demonstrates and discusses techniques used to survey pesticide susceptibility and detect resistance to contact and systemic pesticides in arthropod pests.
JoVE Immunology and Infection
Quantification of Fungal Colonization, Sporogenesis, and Production of Mycotoxins Using Kernel Bioassays
Plant Pathology and Microbiology, Texas A&M University
The devastation of cereal crops by seed-infecting fungi has prompted numerous research efforts to better understand plant-pathogen interactions. To study seed-fungal interactions in a laboratory setting, we developed a robust method for the quantification of fungal reproduction, biomass, and mycotoxin contamination using kernel bioassays.
JoVE Bioengineering
Mass Cytometry: Protocol for Daily Tuning and Running Cell Samples on a CyTOF Mass Cytometer
The steps necessary for daily tuning and optimization of the performance of a CyTOF mass cytometer are described. Comments on optimal sample preparation and flow rate are discussed
JoVE General
Electroantennographic Bioassay as a Screening Tool for Host Plant Volatiles
Plant Mycotoxin Research, U.S. Department of Agriculture, Agricultural Research Service
A method to rapidly screen host plant volatiles by measurement of the electrophysiological response of adult navel orangeworm (Amyelois transitella) antennae to single components and blends via electroantennographic analysis is demonstrated.
JoVE Neuroscience
Vertical T-maze Choice Assay for Arthropod Response to Odorants
Entomology and Nematology Department, University of Florida
A vertical, T-maze olfactometer is described for assaying the behavioral response of arthropods. The olfactometer allows the experimenter to measure choices performed by test subjects when subjected to two potential odor fields. Both attraction to and repulsion from odorants can be measured with this device.
JoVE General
Protocols for Oral Infection of Lepidopteran Larvae with Baculovirus
Department of Entomology, Iowa State University
In this video, we demonstrate oral infection techniques of lepidopteran larvae with baculovirus in order to determine insecticidal efficiency.
JoVE Immunology and Infection
An Analytical Tool-box for Comprehensive Biochemical, Structural and Transcriptome Evaluation of Oral Biofilms Mediated by Mutans Streptococci
1Center for Oral Biology, University of Rochester Medical Center, 2State Key Laboratory of Oral Diseases, Sichuan University, 3Department of General Medicine, Glostrup Hospital, Glostrup, Denmark, 4Department of Microbiology and Immunology, University of Rochester Medical Center
Biofilms formed on tooth surfaces are highly complex and exposed to constant innate and exogenous environmental challenges, which modulate their architecture, physiology and transcriptome. We developed a toolbox to examine the composition, structural organization and gene expression of oral biofilms, which can be adapted to other areas of biofilm research.
JoVE General
Robotics and Dynamic Image Analysis for Studies of Gene Expression in Plant Tissues
1Department of Horticulture and Crop Science, The Ohio State University, 2Department of Plant Pathology, North Carolina State University
We report a method for introduction, tracking and quantitative analysis of GFP expression in plant cells. This method utilizes a custom-designed robotics system for semi-continuous image collection from large numbers of samples, over time. We also demonstrate the use of ImageJ and ImageReady for analysis of image series.
JoVE Bioengineering
A Microfluidic-based Hydrodynamic Trap for Single Particles
1Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, 2Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign
In this article, we present a microfluidic-based method for particle confinement based on hydrodynamic flow. We demonstrate stable particle trapping at a fluid stagnation point using a feedback control mechanism, thereby enabling confinement and micromanipulation of arbitrary particles in an integrated microdevice.
JoVE General
Long-term Lethal Toxicity Test with the Crustacean Artemia franciscana
1Department of Environmental Quality Monitoring, Institute for Environmental Protection and Research, 2Regional Agency for Environmental Protection in Emilia-Romagna
This study concerns the development and standardization of a valuable methodological protocol to determine long-term (14 days) lethal toxicity exerted by chemical substances, industrial wastewater or sewage and liquid environmental samples on the saltwater crustacean, Artemia franciscana.
JoVE Immunology and Infection
A Functional Whole Blood Assay to Measure Viability of Mycobacteria, using Reporter-Gene Tagged BCG or M.Tb (BCG lux/M.Tb lux)
1Department of Paediatrics, Imperial College London, 2Centre for Health Sciences, Barts & The London School of Medicine and Dentistry
We describe an alternative approach to the enumeration of mycobacteria in vitro, which uses reporter-gene tagged mycobacteria instead of colony-forming units (CFU). “Survival” of organisms as well as host response-markers are measured simultaneously, providing a low-cost, versatile and functional system for studies of host/pathogen interactions in the context of tuberculosis.
JoVE Bioengineering
Polymer Microarrays for High Throughput Discovery of Biomaterials
1Laboratory of Biophysics and Surface Analysis, University of Nottingham, 2School of Molecular Medical Sciences, University of Nottingham, 3David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology
A description of the formation of a polymer microarray using an on-chip photopolymerization technique. The high throughput surface characterization using atomic force microscopy, water contact angle measurements, X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry and a cell attachment assay is also described.
JoVE Immunology and Infection
A Cell Free Assay System Estimating the Neutralizing Capacity of GM-CSF Antibody using Recombinant Soluble GM-CSF Receptor
1Bioscience Medical Research Center, Niigata University Medical and Dental Hospital, 2First department of Internal Medicine, School of Medicine, Kyorin University, 3Neosilk Laboratory, Immuno Biological Laboratories Co., Ltd.
We designed a cell-free receptor binding assay in order to estimate the binding of granulocyte-macrophage colony-stimulating factor (GM-CSF) to the receptors. It enables us to evaluate competitive inhibition of biotinylated GM-CSF binding to soluble GM-CSF receptor alpha by GM-CSF autoantibody with excellent reproducibility.
JoVE General
RNAi-mediated Gene Knockdown and In Vivo Diuresis Assay in Adult Female Aedes aegypti Mosquitoes
1Biology Department, New Mexico State University, 2Molecular Biology Department, New Mexico State University
In this protocol we combine RNAi-mediated gene silencing with an in vivo diuresis assay to study the effects knockdown of genes of interest has on mosquito fluid excretion.
JoVE General
Human In-Vivo Bioassay for the Tissue-Specific Measurement of Nociceptive and Inflammatory Mediators
1Department of Anesthesia, Stanford University School of Medicine, 2Department of Anaesthesiology, University of Mannheim, 3Department of Anaesthesiology, University of Heidelberg
A technique is presented for the in-vivo collection of interstitial fluid samples from pertinent tissue sites (here, experimentally inflamed skin) for the measurement of biochemicals mediating pain and inflammation.
JoVE General
High Throughput Screening of Fungal Endoglucanase Activity in Escherichia coli
1Department Of Chemistry and Chemical Engineering, California Institute of Technology, 2Chemistry and Chemical Engineering, California Institute of Technology
We describe a low cost, high throughput method to screen for fungal endoglucanase activity in E. coli. The method relies on a simple visual readout of substrate degradation, does not require enzyme purification, and is highly scalable. This allows for the rapid screening of large libraries of enzyme variants.
JoVE General
The Logic, Experimental Steps, and Potential of Heterologous Natural Product Biosynthesis Featuring the Complex Antibiotic Erythromycin A Produced Through E. coli
1Chemical and Biological Engineering Department, State University of New York at Buffalo, 2Chemical Engineering Department, Massachusetts Institute of Technology
The heterologous biosynthesis of erythromycin A through E. coli includes the following experimental steps: 1) genetic transfer; 2) heterologous reconstitution; and 3) product analysis. Each step will be explained in the context of the motivation, potential, and challenges in producing therapeutic natural products using E. coli as a surrogate host.
JoVE Editorial
May 2012: This Month in JoVE
Here are some highlights from the May 2012 Issue of Journal of Visualized Experiments (JoVE).
JoVE Neuroscience
Paired Nanoinjection and Electrophysiology Assay to Screen for Bioactivity of Compounds using the Drosophila melanogaster Giant Fiber System
1Department of Biological Sciences, Florida Atlantic University, 2Department of Chemistry & Biochemistry, Florida Atlantic University
A rapid in vivo assay to test for neuromodulatory compounds using the Giant Fiber System (GFS) of Drosophila melanogaster is described. Nanoinjections in the head of the animal along with electrophysiological recordings of the GFS can reveal bioactivity of compounds on neurons or muscles.
JoVE Clinical and Translational Medicine
A Zebrafish Model of Diabetes Mellitus and Metabolic Memory
1Dr. William M. Scholl College of Podiatric Medicine, Rosalind Franklin University of Medicine and Science, 2Chicago Medical School, Rosalind Franklin University of Medicine and Science
Metabolic memory is the phenomenon by which diabetic complications persist and progress unimpeded even after euglycemia is achieved pharmaceutically. Here we describe a diabetes mellitus zebrafish model which is unique in that it allows for the examination of the mitotically transmissible epigenetic components of metabolic memory in vivo.
JoVE Neuroscience
Physiological Experimentation with the Crayfish Hindgut: A Student Laboratory Exercise
1Department of Biology, University of Kentucky, 2Department of Biological Sciences, Brock University
In this report we demonstrate techniques that can be used to investigate the biology of the crayfish hindgut. We show how to dissect a crayfish abdomen and study the associated anatomy, physiology and modulation of activity. The peristaltic activity and strength of contractions are measured using a force transducer.
JoVE Immunology and Infection
Optimized Protocol for Efficient Transfection of Dendritic Cells without Cell Maturation
Center for Translational Systems Biology and Department of Neurology, Mount Sinai School of Medicine
We present our optimized high-throughput nucleofection protocol as an efficient way of transfecting primary human monocyte-derived dendritic cells with either plasmid DNA or siRNA without causing cell maturation. We further provide evidence for successful siRNA silencing of targeted gene RIG-I at both the mRNA and protein levels.
JoVE Neuroscience
Neural-Colony Forming Cell Assay: An Assay To Discriminate Bona Fide Neural Stem Cells from Neural Progenitor Cells
1Department of Neurosurgery, University of Florida, 2Department of Anatomical Sciences, Shiraz University of Medical Sciences, 3STEMCELL Technologies, Inc.
This video protocol demonstrates how to discriminate and enumerate bona fide neural stem cells in a mixed population of neural precursor cells using the neural colony-forming cell assay.
JoVE General
Aseptic Laboratory Techniques: Plating Methods
Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles
When working with media and reagents used to culture microorganisms, aseptic technique must be practiced to ensure contamination is minimized. A variety of plating methods are routinely used to isolate, propagate, or enumerate bacteria and phage, all of which incorporate procedures that maintain the sterility of experimental materials.
JoVE Clinical and Translational Medicine
Collecting And Measuring Wound Exudate Biochemical Mediators In Surgical Wounds
Department of Anesthesia, Stanford University School of Medicine
This article provides a detailed and visual description of a methodology for collecting and measuring biochemical inflammatory and nociceptive mediators at the surgical wound site following cesarean delivery. This human bioassay has been used to determine correlations between wound and serum cytokine concentrations and drug-mediated changes in wound cytokines, chemokines and neuropetides.
JoVE Neuroscience
Analyzing Murine Schwann Cell Development Along Growing Axons
1Department of Molecular Embryology, Institute of Anatomy and Cell Biology, University of Freiburg, 2Department of Neuroanatomy, University of Heidelberg, 3FRIAS, University of Freiburg
Here we describe a Schwann cell (SC) migration assay in which SCs are able to develop along extending axons.
JoVE Neuroscience
Visualization of Mitochondrial DNA Replication in Individual Cells by EdU Signal Amplification
1Michigan Research Community, Undergraduate Research Opportunity Program, University of Michigan, 2Department of Neurology, University of Michigan, 3Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan
We developed a sensitive technique to label newly synthesized mitochondrial DNA (mtDNA) in individual cells in order to study mtDNA biogenesis. The technique combines the incorporation of EdU together with a tyramide signal amplification (TSA) protocol to visualize mtDNA replication within subcellular compartments of neurons.
JoVE Immunology and Infection
Protein Misfolding Cyclic Amplification of Prions
1Department of Civil Engineering, University of Nebraska at Lincoln, 2Department of Medical Microbiology and Immunology, Creighton University
Protein misfolding cyclic amplification (PMCA) is an in vitro assay for the study of prion conversion and strain and species barriers. It can also be used as a prion detection assay.
JoVE Immunology and Infection
Rearing and Injection of Manduca sexta Larvae to Assess Bacterial Virulence
Department of Bacteriology, University of Wisconsin-Madison
The method described here utilizes direct injection of entomopathogenic bacteria into the hemocoel of Manduca sexta insect larvae. M. sexta is a commercially available and well-studied insect. Thus, this method represents a simple approach to analyzing host-bacterial interactions from the perspective of one or both partners.
JoVE General
Large Insert Environmental Genomic Library Production
Department of Microbiology and Immunology, University of British Columbia - UBC
Construction of a fosmid library with environmental genomic DNA isolated from the vertical depth continuum of a seasonally hypoxic fjord is described. The resulting clone library is picked into 384-well plates and archived for downstream sequencing and functional screening by the application of an automated colony picking system.
JoVE Neuroscience
Imaging Pheromone Sensing in a Mouse Vomeronasal Acute Tissue Slice Preparation
1Department of Pharmacology and Toxicology, University of Lausanne, 2Department of Genetics and Evolution, University of Geneva
In mice, the ability to detect pheromones is principally mediated by the vomeronasal organ (VNO). Here, an acute tissue slice preparation of VNO for performing calcium imaging is described. This physiological approach allows observations of subpopulations and/or individual neurons in a living tissue and is convenient for receptor-ligand identification.
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