Choosing a manual sequencing cell

Hiranya Roychowdhury hroychow at NMSU.EDU
Fri Jun 27 12:21:05 EST 1997

At 03:33 PM 6/27/97 GMT, Istituto Medicina Legale wrote:
>Dear netters,
>I'm in trouble choosing a manual sequencing electrophoresis apparatus.
>The best value for money cells I've been proposed are Life Technologies S2
>model and Bio-Rad Sequi-Gen GT model. The first has a classical aluminun
>plate heat dispersion system whilst the second has a new heat dissipation
>system based on upper chamber buffer. Plus the second would be provided
>with a specific thermo probe for a dedicated power supply, that could
>mantain more easily a fixed gel temperature.
>On the basis of your experience what system would you suggest? I don't need
>a large gel, so the 31 cm of S2 model instead of 21 cm of Sequi-gen are not
>important to me. 
>Thanks a lot for your help.
>Nicola Cucurachi
>Institute of Legal Medicine
>University of Parma
>43100  Parma ITALY
>tel/fax: 39-521-290358
>e-mail: cnic at

Here are my  $0.02 -worth observations, having used both:
1. The Aluminum plate  (BRL)  works fine and is  comparable to the cathodic heat sink type (BioRad).

2. The latest model of the BRL system is as easy to assemble and pour as the other one.

3. Since the BioRad's system uses the cathodic buffer as the heat-sink, it is extremely difficult to run the gel overnight (for long runs). The buffer evaporates to dangerous level after only 3 hrs. And, I am not sure if an aquous solution is a better heat distributor than the aluminum plate. Smiles happen in both. But if you are not running the gel long, this is not a problem. However, since more than paltry sum is involved in buying these rigs, I like to keep future uses in mind.

4. The spacers for the BioRad rig warps just after one run at 50 C. I tried twice with new spacers and the results have been rather consistent. My guess is that they skimp out on the nitty gritty and focus on making  their rigs look sophisticated. The sharkstooth combs, when used with the wedge spacers, leak samples without fail. So, I have stopped using wedge spacers altogether.

5. Because of  the way the SequiGen GT gels are poured, and due to the design of the rig (molded plate and a layer of air sandwitched by two layers of plastic) it is virtually impossible to detect trapped air bubbles. And you do get bubbles sometimes. It is not difficult to tap the gel assembly to remove the bubbles, even if you saw them forming. So, after  the gel has polymerized, you fill up the cathodic buffer chamber with water, wipe the two sarfaces clean and look for bubbles. If there are any, you simply have avoid loading along those verticals.  

6. The power supply is good and you can use it, along with the temperature probe, with any electrophoresis unit on the face of the earth.

To put it in a nutshell, I would not buy another Sequigen GT.


Dr. Hiranya Sankar Roychowdhury
Plant Genetic Engineering Lab.
New Mexico State University
Las Cruces, NM 88003
Ph. (505) 646-5785
hroychow at

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