Electrocompetent DH10B

[Chris Boyd]

Chris Small (chris at GENOMEX.COM) wrote:
: I'm hoping someone can tell me why my home-made electrocompetent 
: DH10B cells produce both dark blue colonies and very light (almost 
: white) colonies when transformed with a BAC vector (pBELOBAC 11) 
: while the commercial cells yield uniformly blue transformants with 
: the same vector.  I want to make my own cells but they don't look 
: right.

One possibility is that your cells (or cuvettes) are contaminated with
DNA of a (high copy number) plasmid vector, a far commoner problem than
it ought to be.  To test this, try electroporating without adding DNA. 
If you get any dark blues, you need to re-make the competent cells.

Best wishes,

-- 
Chris Boyd                      | from (but not \  MRC Human Genetics Unit
Christopher.Boyd at hgu.mrc.ac.uk  | much longer)  /      Crewe Rd, Edinburgh
http://www.hgu.mrc.ac.uk/Users/Christopher.Boyd          EH4 2XU, SCOTLAND