Difference between two cell strain

[ChenHA]

Ashok Aiyar wrote:

> On Sat, 27 Nov 1999 12:46:15 +0800,
>     Terry Lau (tcklau at hotmail.com) wrote:
> >Hi,
> >
> >Does anyone know the difference between XL1-Blue and XL1-Blue-MR???
> >
> >Thanks in advance!
> >
>
> The genotypes are available on Stratagene's website.  An appropriate
> URL would be http://www.stratagene.com/manuals/200294.pdf
>
> Briefly, XL1-Blue is F-positive, while XL1-Blue-MR lacks mcrABC, mrr,
> and is also F-negative.
>

Where did you get the idea that XL1-Blue is F-positive?  As far as I
know, most (if not all) commonly used cloning strains must be
F-negative.  You safety officer would have a fit if he or she knows that
you are using a F-positive strain for cloning.


>
> Ashok
> --
> Ashok Aiyar
> Department of Microbiology-Immunology
> Northwestern University Medical School