Analysis of Chicken Ribosomal RNA Genes and Construction of Lambda Hybrids Containing Gene Fragments

The ribosomal RNA genes (ribosomal DNA) of chicken are present in approximately 200 copies and are cleaved into two fragments of molecular weight 5 X 10(6) and 12 to 14 X 10(6) by restriction endonuclease Eco RI. Recombinant phages have been constructed in vitro by joining the smaller fragment of ribosomal DNA and the outer arms of DNA from the vector lambdagtWES-lambdaC. In one of the recombinants, the coding strand of the cloned fragment is in the proper orientation for transcription with lambda "early" genes; in the other two the orientation is reversed, with the coding strand in the proper position for transcription with lambda "late" genes.