For a 30-year-old experimental method, gel electrophoresis remains popular. Originally devised as a method to extract nucleic acids from solution, it has evolved into a method for the analysis of everything from protein expression to matching RNA expression to proteins. "When we opened this facility three years ago, some people told me that in three years you won't do gel electrophoresis any more, so why invest in the equipment?" says Thomas Franz, head of the proteomics core facility at the European Molecular Biology Laboratory in Heidelberg, Germany. "Instead we've had an increase in demand of gel electrophoresis of 100% every year for the last three years."
That's not to say that there aren't contenders for the throne. As liquid chromatography continues to improve, it gains more and more adherents in the field of proteomics. And there are plenty of emerging technologies, including surface plasmon resonance and planar waveguide technology for...
Gel Documentation Systems
Have you noticed that everyone seems to have a shiny, new digital camera these days? That's because manufacturing costs have plummeted, flattening the pricing curve for high-end multi-megapixel sensors.
While that's good news for family papparazi, it's also a boon for any lab that runs gels. That's because the same cameras that can be used for your Monday bowling party work just as well capturing a gel image. As a result, low-end, high-resolution imaging equipment has flooded the market. "It's gotten to the point where all you need is the family camera and a darkroom hood," says Ramana Tadepalli, marketing chief at Hoefer, whose revamped product line doesn't even include an imaging system. "The most critical piece of equipment now is the rubber gasket that keeps the light out of the space between the camera and the hood. When a rubber gasket is all the value you can add, it's time to get out of the business."
While low-end systems have been revolutionized, high-end machines have kept up with progress too. Take, for instance, UVP's EpiChemi, which sells for a little under $20,000. It has an advanced Peltier cooling unit to keep the camera cool as ice so that temperature doesn't alter the image. The gel itself is also cooled, ensuring that warping doesn't occur.
Here's a table of the image capture and documentation systems that are available for today's labs, from the high-end to the bargain basement.
Buying an electrophoresis apparatus can be an intimidating task. First you have to decide if you want a horizontal (or submarine) device or a vertical one. Then you have to determine which size format – mini, midi, or large – works best for your lab tasks. Then you must wade through all the different models from the myriad manufacturers. It's enough to make the process of buying a new home seem simple in comparison.
Thus, there's little surprise that many buyers simply choose a manufacturer and stick with it throughout the course of their career. That can be a costly mistake, though. If a simple device is all you need, you might be better off with an off-the-shelf unit from a little-known company with which you can use cheaper standard consumables.
If you want a more specialized machine, it's worth your time to spend some time shopping. Integrated devices, while expensive, are filled with features that could make a big difference in your lab. NextGen Science's a2DE, for instance, automates the casting process and the actual gel run itself: Just pipette the sample into the machine and a finished gel comes out 24 hours later. "It saves a tremendous amount of time if your lab does high-throughput electrophoresis," says marketing manager Lorna Watson.
A similar system from Proteome Systems takes a slightly different tack. While you cast the gels yourself, its ElectrophoretIQ apparatus runs the gel, analyzes it and even teams with a robotic spot-picker, all with minimal human intervention. Market leader GE Healthcare (formerly known as Amersham Biosciences), sells a conglomeration of its equipment for its proprietary Differential Gel Electrophoresis (DiGE) process, which allows multiple staining on the same gel. Below you'll find a selected list of apparatus makers and their wares, separated into separate tables for integrated, horizontal, and vertical systems.
Selected Suppliers of Precast Gels
Biotech Holdings * Gelux
Continental Lab Products
Crescent Chemical Company
The Gel Company
Mirador DNA Design
Owl Separation Systems
While gel electrophoresis has been around for more than three decades, the advanced computing packages designed to analyze gels are recent developments. The ability to minutely analyze the smallest spots is probably the greatest technological advance in gel technology. "The software available today has kept electrophoresis alive as a viable technology," says Chao-Xing Yuan, head of the proteomics core facility at the University of Pennsylvania. "Gels were once little more than illustrations of expression patterns. Now, they're loaded with relevant data."
Most gel-analysis software packages take a high-resolution digital image and process it in multiple ways. For instance, contrast can be increased and borders can be sharpened to make individual spots more clear. More advanced programs can estimate even small differences in protein concentrations and some can quantify concentration levels. Software designed for integrated systems with spot-picking robots can then determine exactly how to excise a spot with micrometer precision.
Some software packages concentrate on saving money. Silk Scientific, for instance, provides a $400 package for small labs that can be used with a plain old flatbed scanner to analyze an image. An even cheaper option is open-source software. GelScape
Below, we have compiled a selected list of gel-related software suppliers, from electrophoresis system manufacturers to independent software providers.
Selected Suppliers of Electrophoresis Software