Transfer of Nucleic Acids Southern and Northern Blot

9 Transfer of Nucleic Acids (Southern and Northern Blot) 

The transfer protocols are the same for DNA and RNA. In opposition to the methods given in Protocol 2.5.3, the forces driving the biomolecules from the separating gel to the receiving membrane are diffusion and capillary flow. This type of transfer is also applicable for proteins, but because the pores of polyacrylamide gels used for protein separation are mostly smaller, transfer times are longer and transfer efficiencies are lower than by electrotransfer. 

Transfer (blotting) of DNA to membranes was introduced by E.M. Southern in 1974, and as a pun the transfer of RNA as the opposite of DNA was named Northern blot and that of proteins got the direction West. 

Agitate the nondenaturated DNA gel (cf. Protocol 2.2.1) carefully in its tenfold volume of Soln. A at RT for 30 min. Skip this step if the DNA is significantly smaller than 5000 bp. 

Decant tbe hydrochloric acid, add ten gel volumes of Soln. B, and shake for additional 30 min, repeating this step with Soln. C instead of Soln. B. 

---