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.
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A Southern blot is a way to analyze DNA molecules. The protocol was developed by Edward Southern. And if you were going to perform a Southern blot, you would first want to separate DNA based upon size in a gel along an electric field... And so your larger fragments, again, at the top; your smaller fragments are going to be at the bottom. When you're done running your gel, you then transfer that to a membrane. So it's like making a sandwich: gel, membrane on top, stack of paper towels. And what you're looking for is, you're going to allow a solution to pass through the gel, up to the membrane, and it's going to be a soft gradient that pushes it through.
Stacie Loftus, Ph.D.
Associate Investigator, Genetic Disease Research Branch
Dr. Loftus's research focuses on the genetic and cellular processes that control mammalian development with the goal of developing a better understanding of inborn errors of embryonic development. Although finding the genes responsible for such conditions does not automatically lead to a cure, such findings can give important clues about what is going wrong at the cellular level, and animal models carrying these genetic alterations can provide researchers with useful ways to test potential therapies. As part of the Mouse Embryology Section, led by Dr. William Pavan, Dr. Loftus is analyzing the molecular and genetic basis of neural crest development.