Direct Assay
Direct Assay - Related Videos
01:09
Directing Effect of Substituents: meta-Directing Groups
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2025
Substituents on the benzene ring that direct an incoming electrophile to undergo substitution at the meta position are called meta directors. All meta directors either have a positive charge on the atom directly bonded to the ring or a partial positive charge. These groups function by withdrawing electrons from the ring through inductive and resonance effects. Consider the carbocation intermediates formed upon the addition of an electrophile on nitrobenzene at the ortho, meta, and para...
17:03
Direct Observation of Enzymes Replicating DNA Using a Single-molecule DNA Stretching Assay
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Cited by 13 •
2010
We describe a method for observing real time replication of individual DNA molecules mediated by proteins of the bacteriophage replication system.
11:00
A Galvanotaxis Assay for Analysis of Neural Precursor Cell Migration Kinetics in an Externally Applied Direct Current Electric Field
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Cited by 26 •
2012
In this protocol we demonstrate how to construct custom chambers that permit the application of a direct current electric field to enable time-lapse imaging of adult brain derived neural precursor cell translocation during galvanotaxis.
09:20
Vectors in Multiple Directions
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2023
Source: Nicholas Timmons, Asantha Cooray, PhD, Department of Physics & Astronomy, School of Physical Sciences, University of California, Irvine, CA This experiment demonstrates how vectors add and subtract in multiple directions. The goal will be to analytically calculate the addition or subtraction of multiple vectors and then to experimentally confirm the calculations. A vector is an object with both magnitude and direction. The magnitude of a vector is simply denoted as the length,...
03:55
Larval Contact Assay: A Procedure to Evaluate Mosquito Larval Mortality following Direct Contact with Test Larvicidal Compound
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2025
In this video, we describe the larval contact assay to evaluate the toxicity of the dopamine receptor antagonist amitriptyline on the third instar stage larvae of mosquitoes, known vectors of several human infectious diseases. Assessing the larval mortality upon incubation with different amitriptyline concentrations over different time intervals helps determine its lethal concentration 50.
FAQs
The measurement is tied to the target’s own presence or activity, rather than to a separate proxy whose behavior is assumed to represent it. This connection can make the resulting signal more directly interpretable as target amount or function. The distinction matters when researchers need to analyze biomolecules, cells, enzyme activity, or pathogen markers with a signal linked to the selected target.
The selective probe or reagent provides the recognition step that connects the sample to a measurable response. When it binds the target or participates in detecting its activity, the interaction produces an optical, electrical, or other physical signal. Selectivity helps focus the measurement on the intended molecule, cell, enzyme activity, or biological marker rather than the sample as a whole.
Target binding can indicate whether a selected molecule or marker is present and support measurement of its amount. Activity-based detection instead reflects what the target is doing, such as an enzyme-driven biochemical reaction. This distinction allows the same general measurement approach to address either abundance or function, depending on whether the signal arises from recognition or biological activity.
Optical, electrical, and other physical responses provide different ways to translate target recognition or activity into data. Regardless of the signal format, its value depends on how clearly it reflects the target’s amount or function. Choosing a suitable response enables rapid analysis across biomolecules, pathogen markers, enzyme reactions, and cellular studies without changing the underlying focus on the target.
A typical workflow begins by combining the biological sample with a selective probe or reagent. The target then binds the probe or contributes activity that generates a measurable response. Researchers record the resulting optical, electrical, or other physical signal and use it to assess the target’s amount or function. The specific format depends on the biological target and the selected detection response.
Researchers may choose this approach when they need rapid information about biomolecules, pathogen markers, or biochemical reactions. Because the measured response is produced by the target itself, the method can support analyses focused on presence, amount, or function. Its uses extend across biological research, diagnostic work, drug evaluation, and investigations of cellular processes.
In drug evaluation, the measured target amount or activity can provide information about a biochemical reaction relevant to treatment research. In cellular biology, signals linked to biomolecules, markers, or cellular processes help investigators examine events occurring within biological systems. These applications show how direct target measurements can connect assay data with both intervention studies and basic research.