Procedure and kit for the cloning of fragments

摘要

A cosmid vector is new and comprises at least 15 kb and no more than 35 kb in size. Independent claims are also included for: (1) an Escherichia coli host cell containing a cosmid as above; (2) a process to conserve an Escherichia coli suspension in 5-20 mM MgSO4 solution comprising cooling the suspension for 30 minutes to -70 degrees C, where the suspension had an initial temperature no higher than 30 degrees C, but higher than 4 degrees C; and (3) a population of bacteria, treated as in (2) for use as host cells for in vitro replication of packaged cosmid DNA.