Dr. Andy

Reflections on medicine and biology among other things

Wednesday, October 26, 2005

Southern blots

Edwin Southern showed that DNA could be separated by size on an agarose gel and then transferred to a nitrocellulose membrane where sequences of interest could be identified by hybirdizing with a radioactive probe. This advance was published in 1975 and the technique almost immediately was termed "Southern blots" (blots because you use a lot of paper towels to draw a solution through the gel onto the membrane, carrying the DNA with it) or just "Southerns". Eventually, a similar approach was applied to RNA and then proteins, which were called "Northerns" and "Westerns."

Southern received the Lasker prize this year for his contributions to early molecular genetics, but we learn from co-recipient Alec Jeffreys that Southern hasn't let success go to his head:
The problem was how to monitor purification. The answer was provided by Ed Southern and his blots (incidentally, and with typical modesty, Ed never calls them Southerns but generally DNA transfers), which we showed, much to our surprise, were capable of detecting single-copy genes in complex genomes. This led to the first physical map of a mammalian gene and one of the first descriptions of introns.


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