separation on an electrophoretic gel of sequences or fragments of genomic
or complementary DNA, partially digested by endonucleases, The fragments
are then 'blotted' onto a membrane and allowed to hybridize with a specific,
labeled probe in order to detect which bands contain the fragment or gene
of interest. Southern blot is particularly useful in detecting large gene
rearrangements/deletions and large trinucleotide repeat expansions.
Definition from: GeneReviews
from the University of Washington and the National Center for Biotechnology Information
Southern blotting is a laboratory technique used to detect a specific DNA sequence in a blood or tissue sample. A restriction enzyme is used to cut a sample of DNA into fragments that are separated using gel electrophoresis. The DNA fragments are transferred out of the gel to the surface of a membrane. The membrane is exposed to a DNA probe labeled with a radioactive or chemical tag. If the probe binds to the membrane, then the probe sequence is present in the sample.