Problems with lamzapII in XL1Blue

[Darren Martin]

Hello

I have been trying to rescue bluescript m13 from XL1 Blue lysogenised 
with lambda zapII containing a +-5Kb insert.  However when I do a prep of 
the rescued plasmid I find the insert has somehow dissapeared - this 
dissapearence sometimes corresponds with the loss of the polycloning site 
but not always.  I have recently managed to obtain a plasmid preparation 
which appears to be about 80% Bluescript M13 with no insert and  20% 
containig something else???? (apparently pBluescript with a part of the 
origional insert still present but its difficult to tell). I was wondering 
whether somebody had encountered the same problem and if so how they managed 
to overcome it.

Thank you in advance to anybody who is able to offer advice.

Darren Martin