OD and IPTG concentration
junk at 127.0.0.1
Sat Dec 22 06:38:56 EST 2001
<Pine.SOL.4.33.0112211041150.15143-100000 at mcmail.cis.mcmaster.ca>, Kyle
Legate <legatek at mcmail.cis.mcmaster.ca> writes on the Fri, 21 Dec 2001
>Please share some methods to maintain vectors without antibiotic. I always
>thought that if the bug has no use for the resistance marker, it would
>dump the plasmid, no exceptions.
The first one that springs to mind is the hok/sok system (parB ?) in R1
type plasmids but can be put into others. Have a look on Pubmed for it
and you should find quite a few references including one in an old
Nature Biotechnology with some interesting stabilisation facts for
various plasmid origins i.e. pACY vectors with p15a replicon get lost
quite quickly without selection. Put in the small hok/sok system (few
hundred bp) and the stability is improved a thousand fold i.e. it is
then very difficult to lose.
Actually this may of value to those people using T7 expression vectors
with lethality problems. Putting in hok/sok should offer a better
selection than ampicillin with the caveat that growth will be slow (due
to toxicity of protein product) and it may actually force selection for
deletion/rearrangment variants :-(
Still may be worth a try.
To all our many readers, have a good Xmas and New Year :-)
The problem with being on the cutting edge is that you occasionally get
sliced from time to time....
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