Bio-Rad DCode™ Universal Mutation Detection System - Manual (Page 24)

6. Align the plates and spacers by simultaneously pushing inward on both clamps at the
locating arrows while, at the same time, pushing down on the spacers with your thumbs.
Tighten both clamps just enough to hold the sandwich in place. Pushing inward on both
clamps at the locating arrows will insure that the spacers and glass plates are flush against
the sides of the clamps (Figure 4.7).
7. Remove the alignment card. Then, remove the sandwich assembly from the casting stand
and check that the plates and spacers are flush at the bottom. If they are not flush, realign
the sandwich and spacers (Repeat steps 5–7).
8. When a good alignment and seal are obtained, tighten the clamp screws until it is finger-tight.
9. Place the proper comb in the sandwich and align it against the notches in the spacers. For
the 7.5 x 10 cm perpendicular gradient gel, insert the middle spacer into the center of the
sandwich until it fits into the middle notch on the comb. Straighten the spacer and the comb.
The bottom of the middle spacer should also be flush against the glass plates (Figure 4.8).
Note: The proper comb for a 7.5 x 10 cm gel is the dual comb that requires a middle
spacer to separate the two 7.5 x 10 cm gels, whereas the 16 x 16 cm gel comb is a
single comb that does not require a middle spacer.
Fig. 4.8. Positioning the middle spacer in a 7.5 x 10 cm gel sandwich assembly.
10. Inspect the comb gasket to insure that the comb gasket is free of gel material. Remove
any polymerized material in the comb gasket vent ports. The soft comb gasket should
lay flat within the comb gasket holder.
Note: To remove the soft comb gasket from the holder, push the gasket away from the
four holes in the holder. To replace the comb gasket, insert the gasket into the holder
with the thick portion in first. Place one corner of the gasket against the top portion of the
holder. With a flat spatula, guide the four tabs into the four holes. Carefully run the
spatula across the gasket to completely set the gasket in place.
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