Colony Hybridisation with biotinylated oligo

Stuart Brown browns at
Fri Jan 22 16:14:00 EST 1993

In article <1993Jan20.145525.17865 at> ahill at (Mr. A.F. Hill) writes:
>I'm trying to set up a system for doing colony hybridisations using a
>biotinylated oligo (23-mer) and using streptavidin-biotin-alkaline phosphatase
>and NBT/BCIP to get the colour reaction...
>I've spotted the oligo onto a filter and can read a signal down to 10pg but
>when i hybe with the oligo and develop the colour i get a nice purple

	Sounds to me like you need better blocking.  Some kits come with
a "Secret Blocking Reagent" which is probably BSA.  Also, you can try
pre-hybridizing with a mixture of salmon sperm and plasmid without insert.

Colony blotting is a very dirty proceedure. I've also read of a technique
where a library is subdivided by plating transformed bacteria on a large
number of plates (maybe 1000 to 10,000 clones per plate), then the colonies 
from each plate are pooled for a large scale plasmid prep (keeping a replica,
of course).  The plasmid pools are then tested by dot blot hybridization.
Pools with positive signal are sudivided and the proceedure repeated, etc.

	-Cheers  -Stu
Stuart M. Brown                             If you can remain cool when all 
U. of Manitoba, Dept. Plant Science         Around you are in panic,
Winnipeg, Manitoba, CANADA
browns at            Then you surely misunderstand the situation

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