David Antonetti wrote:
> We are subcloning two separate PCR products for different cDNAs. We
> have ligated and transformed both inserts into 3 different vectors and
> differenct e coli lines and get the same result. We obtain amp
> resistant colonies but we cannot retrieve any plasmid DNA using either
> alkaline lysis
> and phenol chloroform or using qiagen midi kit. However, if we try to
> PCR from the plasmid prep we obtain product with the correct insert.
> Other plasmids prepared in parrallel are fine. Anyone with any
>> David Antonetti
>dantonetti at psu.edu
Just a very simple checking:
Have you check the competent cells you are using?? Try to plate them before the
transformation, maybe there is an AmpR contamination.
Ah, check the plates as well, i had similar problems and finally it was an old