The E-Gel® Pre-cast Agarose Electrophoresis System by Invitrogen Life Technologies aims to simplify and improve DNA gel electrophoresis. The system essentially contains all the elements needed to perform electrophoresis of DNA in a ‘ready-to-go’ format and as such provides extreme convenience. The major difference between E-Gels and existing methods of DNA electrophoresis is that E-Gels are bufferless, the gels have built in electrodes and also their own ion generating system such that no bathing buffer is required.
Precast gels are supplied in individual packages as 0.8, 1.2, 2 or 4 % gels to resolve different DNA species. The 0.8 % gel, for instance, can resolve DNA fragments from 800 bp to 10 kb but it is possible to resolve fragments as small as 20 bp with higher percentage gels. To perform electrophoresis the E-Gel is simply slotted into a base that contains electrical contacts for the built in electrodes. Two types of base are available, the E-Gel Base requires a separate electrophoresis power supply whereas the E-Gel PowerBase comes with a built in supply. The E-Gel Base that I have used was included in a Starter Pak and is reasonably sturdy and small at ~9 ´ 13 cm. E-Gels require an initial two minutes pre-run period, at 60-70 V or 40-50 mA, before the comb is removed and samples can be loaded. A sample volume of 20-25 ml is required and slightly smaller quantities of DNA, as low as 20 ng for a single band, can be loaded as compared to usual gel electrophoresis. Otherwise, sample composition is the same as usual (in terms of components such as glycerol and dyes) and normal gel-loading buffers can be used E-Gels are run at 60-70 V for around 30 min after which time DNA can be visualized using uv-illumination as the gel already contains ethidium bromide. Running the thin gels for too long will result in damage.
E-Gels certainly do simplify DNA gel electrophoresis. Indeed, I have no reservations with the performance or convenience of this system. Electrophoresis can effectively be performed instantaneously and results are excellent. The attention to detail is also very evident with features such as fluorescent lane numbers making interpretation of gels rapid and simple. Further, E-Gels are compatible with downstream applications such as Southern Blots or band extractions for cloning. My personal reservations are, however, whether the use of E-Gels can be warranted (for my particular uses). Agarose gel electrophoresis of DNA is not hard to perform and an agarose gel is certainly not associated with the same issues as a polyacrylamide gel (lets face it, agarose always sets). Further, packs of 18 gels are about $150, although it is possible to order larger batches of gels. Ideal uses for E-Gels may be in a lab that only needs to run a few agarose gels and does not regularly do molecular biology or a lab, in industry perhaps, that can afford the gels or wants to use a specialized format such as the E-Gel 96 well. In these instances, and others, the performance would undoubtedly be excellent.
Peter Haggie, Ph.D.
Post-Doctoral Fellow
University of California, San Francisco