Cloning of an almost full-length chicken conalbumin double-stranded cDNA

Chicken conalbumin double-stranded cDNA (con-dscDNA) was synthesized from a laying hen oviduct mRNA preparation enriched for conalbumin mRNA (con-mRNA). The dscDNA was inserted by blunt-end ligation into the Sal I site of plasmid pBR322 which had been repaired with DNA polymerase I to create Taq I sites on each side of the inserted fragment. After bacterial transformation, one hybrid recombinant, pBR322-con1, which contains the largest inserted dscDNA (about 2350 bp) was shown to hybridize specifically to the RNA which is translated into conalbumin. Electron microscopic examination of hybrid molecules between con-mRNA and pBR322-con1 DNA indicate that the inserted con-dscDNA is an almost full-length double-stranded transcript of conalbumin mRNA.