I've been trying to transform E.coli cells (JM109, XL-1 BLue and DH5a) with a pET15b vector. The results have been sketchy - only got a single colony of XL-1 Blues on ampicillin plates. The cells grew fine in liquid medium with amp and a miniprep yielded on okay amount of plasmid. However, the company I've sent it to for sequencing cannot find anything: their pcr isn't picking up anything and nothing is seen on a gel. WTH?
Is it possible that the transformation was unsuccessful - and if so, what came out in the miniprep?
Or, the plasmid has been slightly modified but has been successfully used by another group, so I think its unlikely to be that.
Finally - do you think the problem could be with the sequencing??