Eukaryotic expression vectors

[Dennis J. Templeton]

In a previous article, sbhattac at mrc-crc.ac.uk (Dr. Shoumo Bhattacharya B1 061) says:

>Can anyone tell me if eukaryotic expression vectors lacking an eukaryotic
>replication origin manage to replicate as episomes at the time of cell 
division?
>I can't seem to find any info on this.
>
>Thanks
>
>S Bhattacharya
>
Actually, plasmids that do not contain an origin are *lost* during cell 
division, quite efficiently.  Only those that actually integrate into 
the host genome remain stably expressed.  

We have noted that if you inhibit cell division in G1 you can prolong the 
duration  of expression of genes on transfected plasmids: growing cells
lose expression of a puromycin-resistance gene rapidly, but growth
inhibited cells remain puromycin resistant for weeks.  

hope this helps...

dennis