Friday, March 18, 2016

Imaging and Analysis of Genotoxicity using Single Cell Gel/Comet Assay

On March 9, I had the privilege of co-presenting a webinar with Dr. Sachin Katyal from the University of Manitoba. The focus of the webinar was genotoxicity. Genotoxicity, or DNA damage, can be caused by environmental factors, behavior choices, or chemicals. Therefore it is important to test new chemicals in a wide range of applications (drugs, pesticides, dermatological agents, food additives, etc.) to ensure they do not cause damage to DNA. Or in the case of cancer look for treatments that can repair damaged DNA repair mechanisms. While there are many different types of assays to accomplish this goal, one of the most popular and most specific techniques is the comet assay. The term comes from the visual readout of the assay that resembles a telescopic image of a tradional astronomical comet that incorporates both the comet head and a long tail of streaming particles.  Conversely, the comet assay readout is produced after cell treatment with potential DNA damaging agents, mixed with agarose and added to an appropriate slide, lysed and alkaline treated, followed by electrophoresis. Upon staining with a DNA intercalating dye, cells with high levels of DNA damage will exhibit a similar comet shape (Figure 1, close up of a comet; and Figure 2, many comets in a single experiment to provide statistical significance).  These comet images are produced by the fact that fragmented DNA runs through a gel much easier than intact DNA strands. By incorporating the Cytation Cell Imaging Multi-mode readers and Gen5 software, a process that is typically very laborious and subjective can be automated to reduce manual interventions, and also have the subjectivity removed by performing analysis of all samples using mathematical algorithms. The final analysis method was extensively validated by comparisons to results generated using existing comet analysis software packages (Figure 3).

We were pleased to see 300 people register for the webinar, with many watching the actual event and participating in a lively question and answer session.

genotoxicity assays


We invite you to download the webinar recording and published application note from BioTek’s website to learn more about our combined solution to perform these critical genotoxicity assays.

By: BioTek Instruments, Brad Larson, Principal Scientist

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