Bio-Rad DCode™ Universal Mutation Detection System - Manual (Page 27)

7. Place the LO syringe into the gradient delivery system syringe holder (LO density side) by
holding the syringe by the plunger and inserting the lever attachment screw into the lever
groove. Do not handle the syringe. It will dispense the gel solution out of the syringe.
Casting a perpendicular gel is referred to as a bottom filling method, so place the LO
syringe on the correct side of the gradient system.
8. Carefully remove the air bubbles from the HI syringe by turning it upside down (plunger
cap towards the bench) and gently tapping. Push the gel solution to the end of the tubing.
Do not push it out of the tubing as loss of gel solution will disturb the volume required to
cast the desired gel.
9. Place the HI syringe into the gradient delivery system syringe holder (HI density side) by
holding the syringe by the plunger and inserting the lever attachment screw into the lever
groove. Do not handle the syringe. It will dispense the gel solution out of the syringe.
10. Slide the tubing from the low density syringe to one end of the Y-fitting. Do the same for
the high density syringe.
11. Connect the 9 cm tubing with the luer coupling on the sandwich assembly stopcock. Insure
that the stopcock is open and that the vent port is unplugged for the half of the sandwich
being cast.
Note: For a 16 x 16 cm single gel, both stopcocks are open during casting. After casting,
both stopcocks are closed.
12. Rotate the cam wheel slowly and steadily to deliver the gel solution. It is important to cast the
gel solution at a steady pace to avoid disturbances between gel solutions within the sandwich.
Fig. 4.9. Casting a perpendicular gradient gel using the Model 475 gradient delivery system.
13. Plug the vent port and close the stopcock on the gel sandwich when the cam wheel has
reached the stop position. Carefully level the gel sandwich by adjusting the gasket tilt rod.
Be sure to loosen the tilt rod screw and not the sandwich clamp screw.
Note: For a properly cast perpendicular gradient gel it is extremely important to level the
sandwich assembly after casting.
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