Abstract |
Cosmids containing two compatible origins of replication (oris) have been constructed for isolating bidirectional deletions in cloned DNA. The inserted fragment and the cos site are cut, respectively, with a restriction enzyme and lambda terminase to produce two linear fragments that are circularized to produce two autonomously replicating plasmids. Each plasmid contains a different portion of the insert fused to the cosL or cosR sequence. From a series of such deletion-bearing plasmids, the nucleotide sequence of the insert can be determined in both directions using cosL and cosR primers.
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