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Double-transfection (stable) of COS-7 cells

Ashok Aiyar aiyar at ebv.oncology.wisc.edu
Sat Oct 26 10:03:59 EST 1996

On 26 Oct 1996 10:47:30 -0400, Ian A. York <iayork at panix.com> wrote:
>In article <54qj36$fip at bignews.shef.ac.uk>,
>Kevin Mulcahy  <K.Mulcahy at sheffield.ac.uk> wrote:
>>Another possibility may be that the cells were not able to support the 
>>episomal maintainance of two different plasmids with the same origin of 
>>replication? Does naybody know if this is likely in mammalian cells?
>I think this might be a problem, but I'm not positive.  

This is not a problem with oriP containing origins.

>I don't know if the OriP/EBNA1 system is as effective in
>non-human primates.  

oriP works as "well" in monkey cells as it does in human cells.  These
plasmids are maintained at the same efficiency in bovine and canine
cells, but not in murine and avian cells.

There are derivatives of oriP plasmids constructed by Michelle Calos and
her coworkers that are stably maintained in mouse cells as well.

>One other minor point is that the COS line I've been working with is
>extremely resistant to hygromycin.  What levels are you using, and are you
>sure it's giving a good selection?  It sounds like it is, from your post,
>but it might be worth reviewing this.  

This is definitely worth looking into.  I have also worked with a
COS line that was resistant to fairly high levels of hygromycin (~150 ug/ml).

Ashok Aiyar, Ph.D.
Department of Oncology            email: aiyar at ebv.oncology.wisc.edu
University of Wisconsin-Madison                  tel: (608) 262-6697

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