Nucleic Acids Research, Vol 24, Issue 10 1802-1808, Copyright © 1996 by Oxford University Press
M Lobrich, B Rydberg and PK Cooper
The random-breakage mapping method [Game et al. (1990) Nucleic Acids Res.,
18, 4453-4461] was applied to DNA sequences in human fibroblasts. The
methodology involves NotI restriction endonuclease digestion of DNA from
irradiated calls, followed by pulsed-field gel electrophoresis, Southern
blotting and hybridization with DNA probes recognizing the single copy
sequences of interest. The Southern blots show a band for the unbroken
restriction fragments and a smear below this band due to radiation induced
random breaks. This smear pattern contains two discontinuities in intensity
at positions that correspond to the distance of the hybridization site to
each end of the restriction fragment. By analyzing the positions of those
discontinuities we confirmed the previously mapped position of the probe
DXS1327 within a NotI fragment on the X chromosome, thus demonstrating the
validity of the technique. We were also able to position the probes D21S1
and D21S15 with respect to the ends of their corresponding NotI fragments
on chromosome 21. A third chromosome 21 probe, D21S11, has previously been
reported to be close to D21S1, although an uncertainty about a second
possible location existed. Since both probes D21S1 and D21S11 hybridized to
a single NotI fragment and yielded a similar smear pattern, this
uncertainty is removed by the random-breakage mapping method.
ARTICLES
Random-breakage mapping method applied to human DNA sequences
Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA.
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