Colour selection problem on XGal/IPTG plates

[Martin Kennedy]

In article <2dkls2$2pu at mserv1.dl.ac.uk>, osp086 at vaxa.bangor.ac.uk writes:

> DNA ligase. The products as well as uncut bluescript, bluescript cut +
> ligase and bluescript + no ligase (controls) were used to transform fresh
> competant E.coli XL1Blue. These were then plated on Luria agar plates
> containing ampicillin (50ug/ml) and XGal and IPTG at the levels stated in
> Maniatis. After growth for 24 hours the plates were transferred to a fridge
> to allow colour development. This however did not occur. The bacteria seem

> 		Craig Wilding.
> 

Look at your bottle of Xgal, and make sure it is Xgal, not Xglu:i

	5-bromo-4-chloro-3-indolyl-B-D-galactopyranoside

and NOT 5-bromo-4-chloro-3-indolyl-B-D-glucopyranoside
		                       ^^^^^

cos the latter won't work!  


Cheers,

Martin

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