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Caution! Ethidium bromide
is a known mutagen. Always
wear gloves when handling.
Wear UV safety goggles and
protect skin when using any
UV light source.
Note: Ethidium bromide slows
DNA migration by about 15%.
Note: Minimize the staining
time to prevent small nucleic
acid fragments from diffusing
out of the gel.
p16
•
Note 2: Xylene cyanol (0.25%), which migrates more
slowly than bromophenol blue, can be added
as an additional marker if desired. The agarose
concentration determines the position of the
dye bands relative to a polynucleotide.
†
Tracking dyes may be omitted to eliminate obscuring and dragging
effects caused by comigration with smaller nucleic acids.
Well volume
Table 3: Comb specifications
comb
no. of
code no.
wells
HE31A-P-1.0
1 prep/2 ref
HE31A-P-1.5
1 prep/2 ref
HE31A-8-1.0
8
HE31A-8-1.5
8
HE31A-12-1.0 12
HE31A-12-1.5 12
HE31A-16-1.0 16
HE31A-16-1.5 16
*The preparative combs form two reference wells (for MW
standards), one on each side of the preparative well. The
first number is sample volume/mm in the preparative well;
the second is volume/mm in the reference well.
DNA detection
DNA can be detected either by the fl uorescence
of bound ethidium bromide or by autoradiogra-
phy of radiolabeled DNA.
Ethidium bromide (0.5 µg/ml) can be added
to running buffer to monitor sample progress
because the dye's fl uorescence under a UV lamp
reveals band location. (To check progress, turn
off the power supply and remove the lid of the
agarose unit. Hold a portable UV-lamp near the
running tray. Replace the lid and turn on the
power again to resume electrophoresis.)
Alternatively, after electrophoresis, stain the
gel in an ethidium bromide solution (0.5 µg/ml
well
sample vol.
thickness width
per 1 mm
(mm)
(mm)
depth (µl)
1.0
44/6
44/6*
1.5
44/6
66/9*
1.0
6.5
6.5
1.5
6.5
9.7
1.0
3.9
3.9
1.5
3.9
5.8
1.0
2.6
2.6
1.5
2.6
3.9
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