Disappearing plasmids

Marty Stoltzfus cmstoltz at vaxa.weeg.uiowa.edu
Sun Sep 1 22:27:23 EST 1996

Off and on our laboratory has experienced an annoying problem only with
pUC vector clones but never with other high copy plamids such as 
Bluescript or low copy plasmids with the same size inserts.  When we
screen our minipreps, we have high amounts of plasmid DNA (bact. strain is
HB101 in LB + 200 mic./ml AMP). Then when we grow up maxipreps we find
that sometimes even though the bacteria grow normally in AMP we have lost
most or all the plasmid.  This happens even though we have streaked for
single colony isolation.  Why is this happening?  We would appreciate
any help we can get to solve this frustrating problem.
	Marty Stoltzfus

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