Detection of Recombinant DNA

A Petri dish containing bacterial colonies is blotted with nitrocellulose paper. This transfers a large portion of each colony to the paper, which is saturated with a solution that lyses (breaks open) the cells. The DNA of the lysed colonies is denatured with alkali. The nitrocellulose paper is neutralized, washed, and the paper either baked in an oven or treated with ultraviolet light to immobilize the denatured DNA. The DNA on the paper is hybridized with the labeled probe of interest, and the excess label is washed off. The dried paper is exposed to photographic film and the film developed. The exposed spots on the film can be matched with the colonies on the master plate and colonies picked off for further study. 

RFLPs are often a reflection of individual genetic diversity and are not related to a clinical phenotype, but occasionally they can be diagnostic of an inherited disease. This technique is relatively new yet, it has been applied to the prenatal detection of sickle cell anemia, thalassemia, phenylketonuria, a,-antitrypsin deficiency, Huntington s chorea, Duchenne muscular dystrophy, hemophilia A and B, cystic fibrosis, and several other, diseases. 

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