Construction and restriction endonuclease mapping of hybrid plasmids containing Saccharomyces cerevisiae ribosomal DNA.

Fragments produced by partial digestion of Saccharomyces cerevisiae ribosomal DNA (rDNA) with the restriction endonuclease EcoRI were ligated in vitro to the bacterial plasmid RSF2124. The resulting hybrid plasmids were cloned in Escherichia coli. Three hybrid plasmids which contain at least one intact repetitive unit of the multiple, tandem sequences of the yeast rDNA genes have been further characterized. These plasmids have been used to construct a map of the EcoRI, SmaI, HindII and HindIII restriction sites in the individual repetitive units of yeast rDNA.