Missing plasmid after miniprep

[Chris Boyd]

Jon Nakamoto (jnakamot at ucla.edu) wrote:
: Could your host bacteria be full of revertants (the amber mutations on the
: p3 episome can spontaneously revert, especially when under pressure of
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
: high tetracycline/ampicillin concentrations, where revertants are favored
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
: over non-revertants which are depending on the supF in pcDNAI for their
: survival)?

Recent work by Luria and Delbruck (Genetics, 1943, vol 28, pp 491-511)
would seem to contradict this explanation...

: I think that Invitrogen specifically recommends using low
: amp/tet concentrations (lower than you might use for most other
: selections) to avoid this problem.

More likely this is recommended because of inefficient suppression
and/or the synergistic effect of having two antibiotics present.

Best wishes,
--
Chris Boyd                       | from, | MRC Human Genetics Unit
chrisb at hgu.mrc.ac.uk             |  not  |  Western General Hospital
http://www.hgu.mrc.ac.uk/~chrisb |   for |   Edinburgh EH4 2XU, SCOTLAND