ABSTRACT
Southern and Northern blotting are techniques used for the localization and quantification of particular deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) molecules, respectively. Both are specific applications of the filter hybridization technique, in which DNA or RNA is immobilized on a filter and a particular DNA or RNA molecule is identified by complementary base pairing to a labelled probe. For a Southern blot, the gel is first washed in an alkaline solution for a short time to denature the DNA. Once the DNA or RNA is fixed to the membrane, it is ready for hybridization to the probe. The length and composition of the probe affect the degree of hybridization, with longer probes showing greater specificity and resulting in higher sensitivity. Conditions during the hybridization reaction and the subsequent washing steps are critical for determining the stringency of the reaction. Subtractive hybridization and differential screening, involving the use of Southern blotting, was used to isolate 52 candidate plasticity-related genes.
