Ethidium bromide staining of pulsed-field gels showing YAC DNA
amplification and purification. Sizes in kilobases of yeast chromosomes
are indicated, and bands corresponding to YAC DNA are indicated with
arrowheads. (a and b) YAC clones before
amplification, run on a 0.9% agarose gel in 0.5× TBE, at 6V/cm,
4°C for 24 h with 60 s switch time. (a) DNA
from yeast containing a 400-kb YAC; (b) DNA from the
550-kb YAC HSC7E526. The intensity of ethidium bromide staining of the
550 kb YAC (b) is approximately half that of the band
above, which contains two yeast chromosomes (555 and 610 kb) unresolved
from one another. (c) DNA from pYIV3- and pYAM4-modified
HSC7E526, run on a preparative scale in a 1% agarose gel in 0.25×
TAE, at 6V/cm, 4°C for 32 h with 30 and 55 s switch time.
Thirty-nine agarose plugs (0.5 cm × 0.15 cm × 1 cm)
containing YAC DNA were loaded into a sample well 19.5 cm wide and
sealed with agarose. After electrophoresis, the central 17 cm of the
gel was kept for the purification of YAC DNA, and the remainder of the
gel was stained with ethidium bromide and photographed. The two stained
portions of the gel, each containing about 0.5 cm of the preparative
lane, are shown. The intensity of staining of the YAC DNA is 1.5 to
≈2× that of the band above. (d) Gel-purified YAC DNA
before microinjection into fertilized eggs.