Southern blotting is a DNA analysis technique developed by Edwin Southern in 1975 that involves separating DNA fragments by size using gel electrophoresis, transferring them to a membrane, and using a radioactive probe to detect complementary DNA sequences by their position on the membrane after developing an X-ray film. Southern blots are commonly used to verify that a desired DNA sequence has been successfully inserted into the genome of a genetically modified organism.

1. SOUTHERN BLOT
CAROLYN EYRE

2. WHAT IS SOUTHERN BLOTTING?
 A process used for DNA analysis
 Developed by Edwin Southern in 1975
 Is also referred to as DNA blotting
Edwin Southern

3. USE IN GENETICALLY MODIFIED
ORGANISMS
 In genetically modified organisms, Southern blots are used to
make certain that the necessary section of DNA has been
inserted into the genome of the organism being modified.

4. STEP 1
 DNA is separated from it’s source and cut with a restriction
enzyme.

5. STEP 2
 The fragments are put into a gel and are sorted by electrophoresis
in order of length, the shortest at the top and the longest at the
bottom.

6. STEP 3
 Ethidium bromide is then used to make the fragments visible, and
the DNA is taken from the gel and placed in a nylon filter.

7. STEP 4
 Then a radioactive probe is added, which binds to complementary
DNA fragments.

8. STEP 5
 The nylon membrane is then covered with an X- ray film which,
when developed, reveals the position of the radioactive probe.