Plasmid loss after restreaking

[Martin Hughes]

In article <3ugf1u$5n7 at crcnis3.unl.edu>, ddh at unlinfo.unl.edu (dinakar bhattramakki) says:
>
>Hi netters,

>My problem: I transformed Sure18 cells with recombinant pBluescript 
>plasmid. Selected the white transformants on LB+Amp+X-gal+IPTG plates.

With no plasmid DNA and no growth on Amp I suggest that what you actually
picked was contaminating bacteria and not transformants. You may have 
bacteria contaminating your solutions or competent bug stock. Try it over 
with fresh solutions and bugs. 
Alison Cowie