alpha complementation problem ?

Jayakumar, R R.Jayakumar at
Mon Jan 30 14:40:25 EST 2006

You should try preparing fresh X-gal and IPTG solutions.  What is the plasmid you are using?  Moreover, since DH5a cells does not carry lacIq, actually you can use it without IPTG though presence of IPTG will not affect. 
   Or maybe there is an insert in the lacZ gene in the vector

best of luck

-----Original Message-----
From: methods-bounces at
[mailto:methods-bounces at]On Behalf Of Siddhartha
Sent: Monday, January 30, 2006 7:15 AM
To: methods at
Subject: alpha complementation problem ?

I have been tryin to plate Dh5 alpha on to a LBA plate with X-gal and
IPTG but the blue colonies are not coming ?

Is the bug containg the plasmid not stable ? or the x-gal  and IPTG
not woking cause they are 1 yr old solutions ?

Sidharth Parida
Senior Faculty
Center for biotechnology and Research
Neelachal Inst of Medical Sciences
O.C.H.C building , Near Ram Mandir
sidharth4 at

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