Spotting Assay
Spotting Assay - Related Videos
03:08
Light Spot Assay: A Method to Investigate Drosophila Phototactic Behavior
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2023
Drosophila larvae are light-sensitive and respond to changes in surrounding light. This video describes an assay that tests their ability to avoid light, called the light spot assay. The featured protocol demonstrates how to set up the assay with a blue light LED and shows how to record the animal's behavior in response to the light encounter.
06:39
Real-Time Void Spot Assay
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Cited by 14 •
2023
This article describes a new method to study mouse voiding behavior by incorporating video monitoring in the conventional void spot assay. This approach provides temporal, spatial, and volumetric information on the voiding events and details of mouse behavior during the light and dark phases of the day.
05:10
A Spot Plate Assay for Evaluating Oxidative Stress Responses in Bacterial Strains
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2025
This video demonstrates a spot plate assay tailored to assess the oxidative stress responses of bacterial strains. Some strains produce pyomelanin, an antioxidant pigment. Conversely, strains treated with a test agent, leading to reduced pyomelanin production, exhibit increased susceptibility to oxidative stress, resulting in decreased cell viability compared to pyomelanin-producing strains.
08:38
Quantification of the Immunosuppressant Tacrolimus on Dried Blood Spots Using LC-MS/MS
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Cited by 28 •
2015
Here we describe a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) assay to quantify the immunosuppressant tacrolimus in dried blood spots using a simple manual protein precipitation step and online column extraction.
10:45
Finding Your Blind Spot and Perceptual Filling-in
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2023
Source: Laboratory of Jonathan Flombaum—Johns Hopkins University In the back of everyone's eye is a small piece of neural tissue called the retina. The retina has photosensitive cells that respond to stimulation by light. The responses of these cells are sent into the brain through the optic nerve, a bundle of neural fibers. In each retina there is a place somewhere in the periphery where the outputs from retinal cells collect and the bundled optic nerve exits to the brain. At that location,...
FAQs
Serial dilutions extend the measurable range of a Spotting Assay. A concentrated culture may produce dense growth that is difficult to compare, whereas progressively diluted samples reveal differences in colony formation or spot density across cell numbers. This makes the method useful for ranking relative growth between strains or treatments, while remaining semi-quantitative rather than a direct exact cell count.
The response observed on agar depends on the condition imposed after spotting. Nutrient limitation, environmental stress, or antimicrobial exposure can reduce spot density or prevent colony formation in sensitive cells. Comparing growth on a defined test condition with growth under suitable conditions helps distinguish a condition-specific phenotype from generally poor growth, an important distinction when assessing stress tolerance or drug sensitivity.
Spot density and colony formation provide different levels of biological information. A visible spot indicates that at least some cells retained the capacity to grow, while reduced density suggests impaired proliferation or survival within the tested dilution range. Because the readout is semi-quantitative, results are best interpreted as relative differences among strains or treatments rather than as an exact measurement of cell number.
It subjects the tested strains or treatments to the same agar and defined incubation context, so differences in spot appearance can be evaluated side by side. This arrangement is especially useful when screening gene-related growth defects or cellular responses, because the assay links a phenotype to a strain or treatment comparison rather than viewing each result in isolation.
A practical workflow starts with cultures or serial dilutions, transfers small volumes onto solid agar, incubates the plate under the selected condition, and then evaluates colony formation or spot density. The same plate can contain multiple strains or treatments, allowing direct visual comparison. Researchers can therefore screen several phenotypes in a relatively simple format.
Bacteria, yeast, and other microorganisms can be examined with this approach when researchers need to compare viability, growth defects, stress tolerance, or antimicrobial sensitivity. In biology, those comparisons can help investigate gene function and cellular responses by showing how a strain behaves under a defined challenge relative to another strain or treatment.