Bio-Rad DCode™ Universal Mutation Detection System - Manual (Page 28)

14. Immediately remove the tubing from the sandwich assembly stopcock. Place the tubing into
a beaker of water and reverse the cam on the Gradient Delivery System. This will rinse the
tubing and Y-fitting. Remove both syringes from the syringe holder on the gradient delivery
system. Detach the syringe tubing from the Y-fitting. Run or push water out through the
syringe, tubing and Y-fitting several times to get rid of any residual gel solution. It is extremely
important that this is done quickly after casting to avoid any gel polymerization.
15. Let the gel polymerize for about 60 minutes. To cast the other half of the 7.5 x 10 cm gel
format, remove the gasket tilt rod and place it on the other side of the comb gasket. Repeat
steps 4 through 15.
Note: If casting a single 7.5 x 10 cm gel, let the gel solution polymerize for 60 minutes. Carefully
remove the comb gasket; leave the comb in place and pipette (on an opening near the
spacer) a 10 ml gel solution plus initiators in the uncast half of the sandwich to create a dam.
16. After polymerization, remove the comb by pulling it straight up slowly and gently.
17. Continue with Section 8 for electrophoresis.
Assembling the Parallel Gradient Gel Sandwich
For parallel gel formats, a 16 x 16 cm gel sandwich size is recommended. The parallel gel
format does not require special casting grooves in the spacers, so the straight edge portion
(ungrooved side) of the spacers is used. To insure proper alignment, make sure all plates
and spacers are clean and dry before assembly. Use caution when assembling the glass
plate sandwiches. Wear gloves and eye protection at all times.
1. Assemble the gel sandwich on a clean surface. Lay the large rectangular plate down first, then
place the left and right spacers of equal thickness along the short edges of the larger
rectangular plate. To assemble parallel gradient gels, place the spacers so that the grooved
opening of the spacers face the sandwich clamps. When properly placed, the grooved side of
the spacers and the notches will face the sandwich clamps, and the hole is located near the
top of the plates.
2. Place the short glass plate on top of the spacers so that it is flush with the bottom edge
of the long plate.
3. Loosen the single screw of each sandwich clamp by turning each screw counterclockwise.
Place each clamp by the appropriate side of the gel sandwich with the locating arrows
facing up and toward the glass plates (Figure 4.10).
Fig. 4.10. Positioning glass plates, spacers, and clamps.
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