G418 and neomycin?

Martin Offterdinger a8803349.nospam at unet.univie.ac.at
Fri Mar 12 08:23:09 EST 1999

On Fri, 12 Mar 1999 11:46:45 +0800, Dr Mark Watson
<mwatson at rcyllene.uwa.edu.au> wrote:

>Hi All
>A question from a non microbiologist.  If a plasmid has neomycin
>selection why can't you use neomycin as the selection antibiotic?
>Everyone uses G418 (Geneticin).  What is the basis for using
>G418 vs neo?  Toxicity? Cost? some other reason that I'm just too
>dumb to figure out.

Hi mark!
I have asked the very same question a few month ago and there is a lot
of confusion on that topic; what I found out (and what is true  i
think) is:
1)The neomycin resistance gene NeoR confers resistance against 
1. neomycin
2. kanamycin
3. G418 (=geneticin)
2) this gene can be expressed in both bacteria and eukaryotes!
3) Bacteria without the neo gene are sensitive against neomycin,
kanamycin and G418
4) eukaryotes without the neo gene are resistant to kanamycin and
neomycin but sensitive to G418(=genticin)
Conclusion: For selection of resistant  Eukaryotes you have to use the
very expensive compound G418, for selection of prokaryotes (bacteria)
you normally use either neomycin or kanamycin (slightly cheaper)
All right?

Martin Offterdinger
Internal Med.I,Dept. Oncology
University of Vienna
E-Mail:a8803349.nospam at unet.univie.ac.at
(remove .nospam before mailing)

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