Genomic Library Screening

[Warren Gallin]

In Article <1994Feb26.213031.1903824 at sue.cc.uregina.ca>,
ZACHARIAS at Meena.CC.URegina.CA (Tracey Zacharias) wrote:
>I am screening a lambda genomic library and think I have some positives.       

>I have picked them, grown them up in LB + E.coli and now want to screen
>them again.  I am thinking of just taking about 5 microL and dotting 
>it on a membrane and then treating just as if I had done a plaque 
>lift.  Is this a reasonable approach?  I cannot find any references 
>that do it this way.  Does the LB that the lambda was grown up in have
>an effect? Will I get a bunch of positives that aren't really positive 
>due to LB?  
>
   If you have plaque purified the phage, what you are proposing is
redundant.  If you haven't plaque purified, then you need to replate from
your stab and get a single positive plaque.
   What I usually do once a clone is plaque purified is to purify some of
the DNA and do a Southern blot.  You need the information anyway, and you
will be confirming that the hybridization is to a specific DNA fragment.
Warren Gallin,
Department of Zoology, University of Alberta
wgallin at gpu.srv.ualberta.ca