T/A cloning

Simon Dawson Simon.Dawson at nott.ac.uk
Fri Jan 19 04:09:08 EST 1996

Simon TWigger wrote:
> It is also possible that the blue colonies have the insert in as well,
> but for whatever reason, this hasn't inactivated the B-gal gene. I have
> found this on a number of occasions using pGEM-T. If you screen the
> whites and some of the blues using colony PCR you find that the insert
> is in both. It doesn't always happen and I pick whites in preference to
> blues, but if all else fails, check out a few blues and you might be in
> luck.
> Also you may find that you have light blue colonies (mainly white with
> a light blue center for example) as opposed to completely white
> ones...quite often these will also have the insert.

Yeha! Way to go Dr. Twigger! ;)
  Seriously though, I have had as many as 50% of my positive clones turn out 
blue.....usually light blue wrt a genuine negative, but blue all the same.


Dr. Simon Dawson       TEL:+44 (0)115 9249924 ex. 44789
Dept. of Biochemistry  FAX:+44 (0)115 9422225
Queens Medical Centre  Email:Simon.Dawson at .nott.ac.uk
Clifton Boulevard      http://www.ccc.nottingham.ac.uk/~mbzspd/Simon.html
U.K.                   "Back off man, I'm a scientist!" - Bill Murray.

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