Cell Density Separation
Cell Density Separation - Related Videos
02:17
Separation of Bacteria by Capsule Amount Using a Discontinuous Density Gradient
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2025
Source: Feltwell, T., et.al. Separating Bacteria by Capsule Amount Using a Discontinuous Density Gradient. J. Vis. Exp. (2019)This video demonstrates the use of a discontinuous density gradient to separate bacterial strains based on capsule amount. By centrifuging a transposon mutant library through the gradient, bacteria with different capsule densities localize to distinct layers. The separated fractions can then be collected for downstream analysis.
05:52
Separating Bacteria by Capsule Amount Using a Discontinuous Density Gradient
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Cited by 13 •
2019
We demonstrate the use of discontinuous density gradients to separate bacterial populations based on capsule production. This method is used to compare capsule amount between cultures, isolate mutants with a specific capsule phenotype, or to identify capsule regulators. Described here is the optimization and running of the assay.
04:11
Exosome Isolation: A Density-based Ultracentrifugation Technique Using Sucrose Cushion to Separate Exosomes from Conditioned Media of Cultured Cells
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2023
This video describes a density-based ultracentrifugation technique for isolating exosomes from conditioned media harvested from human embryonic kidney cell cultures using a 25% (w/w) sucrose cushion prepared in deuterium oxide. The isolated exosomes can be used for downstream applications.
09:19
Utilizing Soil Density Fractionation to Separate Distinct Soil Carbon Pools
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Cited by 3 •
2022
Soil density fractionation separates soil organic matter into distinct pools with differing stabilization mechanisms, chemistries, and turnover times. Sodium polytungstate solutions with specific densities allow the separation of free particulate organic matter and mineral-associated organic matter, resulting in organic matter fractions suitable for describing the soil response to management and climate change.
09:48
Separation of Spermatogenic Cell Types Using STA-PUT Velocity Sedimentation
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Cited by 111 •
2013
The STA-PUT method allows for the separation of different populations of spermatogenic cells based on size and density.
FAQs
A cell migrates through the density-gradient medium until it reaches a region whose density matches its own buoyant density. Cells with different buoyant densities therefore stabilize in different parts of the gradient. This behavior allows researchers to collect separated fractions and obtain enriched populations rather than analyzing all cellular material as one mixed sample.
A density gradient helps reduce the complexity of a starting sample by separating cellular populations into distinct fractions. Enriched fractions make measurements more focused because investigators can examine selected leukocyte populations or peripheral blood mononuclear cells with less unrelated material. This improves the interpretation of immune responses and disease-associated cellular changes in downstream experiments.
Leukocyte populations may occupy different regions of a density gradient when their buoyant densities differ. Collecting those regions separately produces fractions enriched for particular cellular groups, which can then be examined independently. In immunology, this separation supports more defined assessments of immune-cell composition and behavior than would be possible with an unsorted mixture.
A typical workflow places the sample into a density-gradient medium, applies centrifugation to generate separated density layers, allows cells to migrate to matching regions, and collects the resulting fractions individually. The recovered material can then be prepared for flow cytometry, culture, or molecular assays, depending on whether the goal is cellular measurement, experimentation, or molecular analysis.
In infection research, density-based fractionation can help enrich host cells, separate leukocyte populations, or reduce microbial and cellular debris before analysis. Cleaner fractions support clearer measurements of pathogen interactions and immune responses. The method is therefore useful when mixed starting material could obscure changes in host-cell composition or complicate interpretation of infection-related experiments.
Separated fractions can support several types of investigation. Flow cytometry can be used to analyze defined cellular populations, culture can support further cellular experimentation, and molecular assays can examine fraction-associated molecular changes. Because the fractions are enriched and less mixed, these applications can provide more interpretable information about immune responses, pathogen interactions, and disease-associated cellular changes.