In molecular biology, gel electrophoresis is a process that separates fragments of DNA or RNA by size for analysis. Invitrogen E-Gels are a ready-to-use product line designed to make this process faster and more convenient. They are self-contained agarose gel cassettes that come pre-made, streamlining a time-consuming laboratory procedure.
The E-Gel Precast System Explained
The defining feature of the E-Gel system is its pre-cast, disposable cassette format. Unlike traditional methods that require scientists to manually prepare agarose gels by melting powder in a buffer and pouring it, E-Gels eliminate these preparative tasks. They provide a standardized, ready-to-run gel in a UV-transparent plastic cassette, which saves time and contributes to more consistent results between experiments.
A key element is the integration of necessary reagents directly into the gel matrix. Many E-Gels contain a fluorescent dye, like SYBR Safe, which binds to DNA and allows it to be visualized under specific light wavelengths. The gels are also bufferless, containing the ions needed to conduct an electrical current, which removes the need for large tanks of liquid running buffer and simplifies the setup.
These specialized gels are designed for dedicated hardware like the E-Gel Power Snap Electrophoresis System. This compact device is both a power supply and an imaging system for viewing results. The hardware has a small footprint and includes pre-set programs optimized for different E-Gels, further simplifying the workflow to a simple load, run, and analyze process.
Running Samples with E-Gels
The workflow for an E-Gel is straightforward. A researcher prepares DNA samples by mixing them with a loading buffer that contains a dense substance like glycerol to help the sample sink into the wells and a tracking dye to monitor the gel’s progress. The samples are then pipetted into the wells at one end of the E-Gel cassette.
The loaded cassette is inserted into a compatible device, like an E-Gel Power Snap, ensuring a proper connection to the electrodes. The user selects a pre-programmed run protocol tailored to the specific E-Gel, which removes the guesswork from setting voltage and time parameters.
When the program starts, an electrical field is applied across the gel, causing negatively charged DNA fragments to move toward the positive electrode. Smaller fragments move more easily through the agarose matrix, separating the DNA into bands based on size. Many systems allow for real-time monitoring through a transparent safety cover, so the user can watch the bands separate.
After the run, which can be as short as 10 minutes, results are ready for visualization. The E-Gel Power Snap system has a built-in blue-light transilluminator and camera. The light causes the dye-bound DNA to fluoresce, and the camera captures a high-resolution image of the bands, avoiding the need to move the gel to a separate imaging station.
Key Advantages of the E-Gel Platform
The primary advantages of the E-Gel platform are speed and convenience. The pre-cast, ready-to-use design eliminates gel pouring and buffer preparation, which reduces hands-on time and the potential for human error. This leads to more reliable results and allows the entire process to be completed much faster than traditional methods.
The system also offers safety benefits. Many E-Gels use SYBR Safe, a less hazardous fluorescent dye than the mutagen ethidium bromide. The integrated blue-light transilluminator also avoids exposing the user and the DNA sample to damaging UV radiation.
Finally, the pre-packaged nature of E-Gels reduces laboratory waste. The bufferless systems eliminate the need for large volumes of liquid running buffer, and the compact size of the gels and hardware conserves bench space in a busy lab environment.
Common Applications of E-Gels in Research
E-Gels are frequently used in research for several routine tasks:
- Analysis of polymerase chain reaction (PCR) products. Researchers run a small amount of a PCR reaction on an E-Gel to verify that the DNA amplification was successful and that the fragment is the correct size.
- Screening of DNA clones. After a cloning experiment, E-Gels provide a fast way to analyze plasmid DNA from multiple clones to identify which ones contain the correct DNA insert.
- Checking restriction enzyme digests. Researchers use E-Gels to confirm that enzymes have cut DNA at the correct sequences by observing the resulting fragment sizes.
- Specialized tasks. Certain gels, like E-Gel SizeSelect II, are used for purifying DNA fragments of a specific size for next-generation sequencing. Other gels, like E-Gel EX, offer higher resolution for separating fragments that are close in size.