ABSTRACT
DNA fragments containing sequences complementary to globin mRNA were isolated from pigeon reticulocytes using the binding of the poly(A) sequence of the globin mRNA DNA hybrids to poly(U)-Sepharose. The cloning of DNA sequences in plasmid recombinants has made it possible to amplify specific sequences to an extent that they can be used for preparative purposes. In mtDNA digests made with endonuclease HapII, which gives about 70 separable fragments under these conditions, only about 10% of the fragments were firmly bound to poly(U)-Sephadex. This shows that the number of clusters long enough to result in binding is limited in yeast mtDNA and it suggests that large fragments are bound by only one or a few clusters. Cellulose-bound DNA complementary to ovalbumin mRNA was used in a continuous hybridization system to isolate single-stranded DNA molecules containing the ovalbumin gene. Fragmented DNA segments containing the ovalbumin gene were enriched 300-to-350-fold in one cycle of purification.
