Running gels may seem like a routine part of the biology experiments we run day-in and day-out. It is our lab bread and butter, and without out it, we could not complete key steps in our analyses. But crime-fighting took a historic turn with the introduction of several key molecular techniques that we often consider trivial yet indispensable. These techniques include advancements using polymerase chain reaction, as well as gel electrophoresis.
DNA testing has played a major role in forensic science since the 1980s. It was made possible by gel electrophoresis—one of the critical steps that allows investigators to establish a DNA fingerprint, and is still being used for this purpose. It has been responsible for the iconic images of laboratory results shown in television commercials, court cases, and television shows such as CSI. There is even a Crime Scene Investigator PCR Basics Kit that is used to teach students about the whole process.
These molecular techniques have simultaneously been applied to paternity testing, directly allowing for famous television lines such as “You ARE the father!” But while sensationalized headlines enabled by gel electrophoresis are glamorous (or at least notorious), the actual technical process of running gels is far less so. Once loaded, the samples of DNA or protein are off and running—for a while. Many scientists run samples of DNA through an agarose gel, often for genotyping—and often with hundreds or thousands of samples to analyze (I’m looking at you, zebrafish labs). Then there are the scientists running linearized protein samples through a polyacrylamide gel for protein expression analyses such as Western blotting. Did you get a frowning band? D’oh! Try again. It can be a tough job, for which scientists seldom receive (or expect) thanks or praise.
Regardless of lab scientists’ microcosmic plights, advances in genealogical testing were made possible thanks to many studies that were applied to the development and optimization of gel electrophoretic techniques. This article provides a more detailed history and specific explanation of the principles involved in gel electrophoresis, as do core textbooks in molecular biology.
Gel electrophoresis is still a pivotal step in many modern experiments. Although whole genome sequencing is often the go-to technique and the currently hot trend, techniques based on gel electrophoresis are ever-evolving. This comprehensive review includes a discussion of DNA capillary electrophoresis in entangled polymers, pulsed field gel electrophoresis, microfluidic separation, fluorescence burst experiments much like flow cytometry, and DNA stretching. If you’ve ever been curious about forensic science or wondered about how to push the boundaries of electrophoresis use, there are many ways to become involved.
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Mike has a Ph.D. in Biomedical Sciences from the University of California, Riverside, a M.S. in Cell and Molecular Biology from San Francisco State University, and a B.A. in English from the University of California, Berkeley.