truncated vector

Alexander N. Kukushkin kan at
Wed Sep 4 02:57:59 EST 1996

Dear netters,
I try to clone intermediately some promoter fragments by pUC19 and Bluescript
plasmids. These fragments were cleaned up by NucleiClean (Sigma) and
contained the blunt (Klenov-filled Bal31) and sticky (Hind3) ends. After
ligation on SmaI- and Hind3-sites and Ca-transformation of the JM109 competent
cells many white clones were obtained. As a result, I got the necessary
constructs. However, most of analyzed white clones carried the truncated
vectors without the inserts. There were disturbed the remaining polylinker
sites and the adjoining part of the lacZ gene. It is strange because the host
strain JM109 is endA1(-) and recA1(-) in particular. Can anyone explain this
phenomenon? Any suggestions will be greatly appreciated!
Please let me know by replying to kan at
Thanks in advance.

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