big DNA in XL-1 cells

Dr Dave Parcej parcej at
Fri Feb 27 02:35:40 EST 1998

We also had trouble with big plasmids in XL1-Blue. Now we use Top10F (from
Invitrogen). These have much higher transformation efficiencies for the
large  vector and are fully compatible with blue/white screening.
Hope this helps

In article <34F5B79B.542686C5 at>, Yelena Shifman
<shifman at> wrote:

> Dear Colligues!
> I got a real problem. We subcloned a piece of CREB = 9Kb (the whole gene=25Kb)
> into Bluescipt. After transformation Xl-1 cells grew extreemely slow (it took
> 3 days just to get normal saturated culture). We tried other cells Xl-Gold,
> DH5alpha) with the same effect.
> Either CREB makes something really toxic or else... 
> I would appreciate any suggestions.
> Y. Shifman
> Shifman at

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