R
E
C I P E S
III.
Agarose Gel Electrophoresis
2.0%
Agarose
Makes 200
ml. Use fresh or store jelled at room temperature (several weeks).
- Add 4.0
g agarose (electrophoresis grade) to 200 ml 1X TBE electrophoresis buffer
in a 600 ml beaker or Erlenmeyer flask.
- Stir
to suspend agarose.
- Cover
beaker with aluminum foil, and heat in boiling-water bath (double boiler)
or on hot plate until all agarose is dissolved (approximately 10 minutes).
or
Heat uncovered in a microwave oven at high setting until all
agarose is dissolved (3-5 minutes per beaker).
- Swirl
solution and check bottom of beaker to insure that all agarose has dissolved.
(Just prior to complete dissolution, particles of agarose appear as
translucent grains.) Reheat for several minutes if necessary.
- Cover
with aluminum foil, and hold in a hot-water bath (at about 60°C) until
ready for use. Remove any "skin" of solidified agarose from surface
prior to pouring.
Notes:
i. Samples
of agarose powder can be preweighed and stored in capped test tubes
until ready for use.
ii. Solidified
agarose can be stored at room temperature and then remelted over a boiling-water
bath (15-20 minutes) or in a microwave oven (3-5 minutes per beaker)
prior to use. Always loosen cap when remelting agarose in a bottle.
iii. When
remelting agarose evaporation will cause the concentration to increase.
If necessary, compensate by adding back a small volume of water.
1 µg/ml Ethidium Bromide Staining Solution
Makes 500
ml. Store in dark at room temperature (indefinitely).
CAUTION:
Ethidium bromide is a mutagen by the Ames microsome assay and a suspected
carcinogen. Wear rubber gloves when preparing and using ethidium bromide
solutions.
- Add 100
µl of 5 mg/ml ethidium bromide to 500 ml deionized or distilled water.
- Store
in unbreakable bottles (preferably opaque). Label bottles "CAUTION:
Ethidium Bromide. Mutagen and cancer-suspect agent. Wear rubber gloves
when handling."
Note:
Ethidium bromide is light sensitive; store in dark container or wrap
container in aluminum foil.
Loading Dye
Makes 100
ml. Store at room temperature (indefinitely).
0.25
g bromophenol blue (m.w. 669.96)
0.25 g xylene cyanol (m.w. 538.60)
50.00 g sucrose (m.w. 342.30) (or 50 ml of glycerol)
1.00 ml 1M Tris (pH 8.0)
If using
sucrose:
- Dissolve
bromophenol blue, xylene cyanol, sucrose and Tris in 60 ml deionized
or distilled water.
- Add deionized
or distilled water to make 100 ml total solution.
If using
glycerol:
- Dissolve
xylene cyanol, bromophenol blue, and Tris in 49 ml of deionized or distilled
water.
- Stir
in 50 ml of glycerol to make 100 ml total solution.
0.2% Methylene Blue Stock Solution
Makes 100
ml. Store at room temperature (indefinitely).
- Weigh
out 0.2 g methylene blue-trihydrate (m.w. 373.9) and add to 100 ml of
distilled water.
- Stir
until completely dissolved.
0.025%
Methylene Blue Staining Solution
Makes 500
ml. Store at room temperature (indefinitely).
- Add 62.5
ml of 0.2% methelyene blue stock solution to 437.5 ml of distilled water.
- Stir
to mix.
pBR322/BstN
I Size Markers (0.1 µg/µl)
Either buy pBR322 pre-cut with restriction enzyme BstN I from New England Biolabs
(#N3031) or prepare it according to the following protocol:
Makes 1 ml
Store at
-20° C (1year).
- Add 10
µl of a solution of 10 µg/µl pBR322 to 75 µl distilled, autoclaved water.
- Add 10
µl 10x buffer (provided by supplier of the enzyme).
- Add 5
µl BstN I restriction enzyme, and incubate at 60°C for 60 min.
- Electrophorese
5 µl (plus 1 µl loading dye) in a 1-2% agarose gel to check for complete
digestion. Exactly 5 bands should be visible, corresponding to 1,857
bp, 1,058 bp, 929 bp, 383, and 121 bp. Any additional bands indicate
incomplete digestion; add additional enzyme and incubate again at 60°C.
10X Tris/Borate/EDTA (TBE) Electrophoresis Buffer
Makes 1
liter. Store at room temperature (indefinitely).
- Weigh
out:
1 g NaOH (m.w. 40.00)
108 g Tris base (m.w. 121.10)
55 g boric acid (m.w. 61.83)
7.4 g ethylene diamine tetraacetic acid (EDTA, disodium salt, m.w. 372.24)
- Add all
dry ingredients to 700 ml deionized or distilled water in a 2 l flask.
- Stir
to dissolve, preferably using a magnetic stir bar.
- Add deionized
water to bring total solution to 1 liter.
1X TBE Electrophoresis Buffer
Makes 10
liters. Store at room temperature (indefinitely).
- Into
a spigoted carboy, add 9 liters deionized or distilled water to 1 liter
of 10X TBE electrophoresis buffer.
- Stir
to mix.
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