Biochemical Techniques and Instrumentation

5.2.1. Northern Blotting

Northern blotting is a technique is used for the detection of RNA fragments instead of DNA fragments. The technique is called “Northern” simply because it is similar to “Southern” blotting. Northern blot technique was developed by James Alwine, David Kemp and George Stark of Stanford University, in 1977. There are 3 types of RNA:

1. tRNA - transfer RNA, which is active in assembling of polypeptide chains
2. rRNA - ribosomal RNA, which is a part of the structure of ribosomes
3. mRNA - messenger RNA, which is the product of DNA transcription and used for translation of a gene into a protein

In this methods, RNA is transferred onto the membrane from the gel. There is no depurination step, as RNA itself is small enough to be transferred easily. The detection of RNA is done with a RNA hybridization probe complementary to part of or the entire target sequence.