The ovalbumin gene. Insertion of ovalbumin gene sequences in chimeric bacterial plasmids

Double-stranded ovalbumin DNA was amplified and purified by the cloning of bacterial transformants. The double-stranded DNA was synthesized from a complete complementary DNA transcript of ovalbumin mRNA using Escherichia coli DNA polymerase I and the self-priming ability of the initial transcript. After S. nuclease treatment, poly(dA) was added to the 3' termini with terminal deoxynucleotidyltransferase and the ovalbumin gene was hybridized to a linear plasmid DNA, pMB9, containing 3'-poly(dT) termini. This hybrid molecule was used to transform the E. coli strain X1849. The cloned transformants contained from 30 to 53% of the complete ovalbumin DNA as determined by hybridization with full length cDNA. The length of the inserts was confirmed by treatment of the isolated plasmids with the restriction enzyme Hha I. Separation of the fragments by agarose gel electrophoresis showed that the amount of inserted DNA in clones tested varied from 680 to 1090 base pairs.