Comet Assay / Foci

Single Cell Based DNA Damage Analysis

Automation of quantitative DNA lesion analysis based on single cells.

Toxicologists and radiation biologists nowadays can choose from many established tests to assess DNA damage. However, many of these tests are based on counting events which are only indirectly related to the original lesion. Chromosomal aberrations and micronuclei, for instance, are caused by DNA breaks, but the microscopically visible structure is the outcome of complex cellular processing. Comet assay and γ-H2AX foci analysis, however, bear the chance to directly assess the damage on a single cell level. As part of the toxicology portfolio, MetaSystems automated both assays with Metafer.

Comet Assay

The Comet (single cell gel electrophoresis) assay is a method for obtaining the amount of DNA fragmentation of single cells. It is widely used to estimate DNA damage caused by chemicals or radiation, for example to test individual sensitivities to ionizing radiation in cancer patients. The assay involves image analysis of the migration pattern caused by fragmented DNA in an agarose gel. The more fragmented the DNA is, the more the DNA fragments migrate, forming a structure that resembles the tail of a comet. Damage quantification is then based on the calculation of the 'head' (the actual cell) and the 'tail' (the migrated fragments).

Metafer automatically detects and selects cells in single cell gel electrophoresis samples. All selected cells are analyzed for all features important for the Comet assay (tail moment, Olive tail moment, %DNA in tail, tail and head dimensions, and many more). The background conditions in the images are measured, and results data can be corrected for uneven background. Comets are detected based on user-defined morphological criteria and thresholds between cells and background. Detected comets are displayed in the cell gallery, and each comet can be relocated with a single mouse click. Data are displayed in convenient histograms and/or scatter plots, which are continuously updated as the scan progresses. Metafer supports multiple exposure times for image acquisition. Images having an extended dynamic range for more precise and reliable measurements.

Metafer is the perfect system for automated, high-throughput Comet assay analyses. It supports changing slide dimensions, e.g. to use multi-gel specimens.

Metafer also includes a license for interactive Comet assay analysis software. The software provides the same analysis options like Metafer, and it is also available as a stand-alone system. If Metafer's signal analysis features are used, there are many more options for automated target cell selection. For example, such a system can automatically detect Hedgehog Comets and distinguish their results from the other cells.

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gamma-H2AX Foci

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Scoring Micronuclei

Automated Micronucleus Tests

High Throughput

Scalable solutions for large laboratories

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