9 Things You Didn’t Know About Gel Electrophoresis

Our electrophoresis technology is fast! But there’s still time to share a few of these facts while your DNA runs!

1. While gel electrophoresis and DNA visualization are a match made in heaven, it took a long time for the two to meet. Electrophoresis separation was developed in 1930s but didn’t make the leap to biology until the 1960s.  Instead, early molecular biologists used centrifugation to separate and see DNA. This required huge sample amounts, lots of time, and heavy lab machinery.
2. Seeing DNA in gels has gotten safer and safer. Originally DNA in electrophoresis gels was seen be adding a radioactive label to each fragment – a method that was sensitive but also time consuming and dangerous. In 1972 two labs simultaneously discovered that ethidium bromide could be used to fluorescently stain DNA. Today several even safer staining methods are available.
3. Gel electrophoresis is a big business. The global market for gel electrophoresis in 2020 was estimated at $1.2 billion and continues to grow. Insiders predict a 6% increase by 2026.
4. DNA gel electrophoresis can detect VERY small DNA differences. Specialized “high-resolution” agarose can differentiate between fragments with 2% size difference within the range of 200-1000 bp. That’s around 4 base pairs!
5. With a little fiddling gel electrophoresis can also handle VERY big DNA. How big? Up to 2Mb (2,000,000 base pairs)! Pulse field gel electrophoresis (PFGE) is like standard electrophoresis but with three current directions – one parallel to the gel and two to the left/right at 60 degrees. Large DNA fragments are added to the gel and a current is started down the center but then switched periodically throughout the run. PFGE is used for genotyping and for the genetic fingerprinting of bacteria.
6. Agarose is king when it comes to the gels of gel electrophoresis. One reason for this is because it exhibits thermal hysteresis. This means that it gels (goes from a liquid to a solid) at a different temperature then it melts (goes from a solid to a liquid).
7. Gel electrophoresis and sustainable marine farming have more in common than you’d think. Agarose comes primarily from the cell walls of the red algae Gelidium spp. and Gracilaria spp.. In 2015 overharvesting of these species led to a global shortage but also an industry overhaul. Today most agarose comes from red algae farms rather than from harvested wild species.
8. Gel electrophoresis requires charged particles (like negatively charged DNA and RNA) but there are work arounds. For examples, when working with proteins researchers pretreat the proteins with a detergent called SDS (sodium dodecyl sulfate). This both unfolds the protein into a linear shape and coats them in a negative charge which then allows for their migration and size separation.
9. Gel electrophoresis isn’t just for DNA, RNA, and protein. New methods are being used to characterize, separate, and isolate nanoparticles like gold, silver, zinc oxide, and silicon dioxide.