Sv: Clonetech DSRed

Gregers Gram gregers.gram at INET.UNI2.DK
Wed Nov 24 03:00:23 EST 1999

The DsRed1-1 plasmid confers resistance to kanamycin/neomycin and not ampicillin. 

Gregers Gram

----- Original Message ----- 
From: Tom Knight <tk at pasteur.ai.mit.edu>
To: <fluorpro at net.bio.net>
Sent: Tuesday, November 23, 1999 11:12 PM
Subject: Clonetech DSRed

> We're having trouble with transformations of the Clonetech DSRed and I
> was wondering if others are having similar problems.
> We transform (into DH5a), and mostly get white colonies.  We grow them
> for a while and sometimes a few isolated colonies turn distinctly red;
> we then streak these colonies out, and the result is again a set of
> white colonies.  As far as we can tell, the medium has adequate
> ampicillin (100ug/ml), so the cells are unlikely to be losing the
> plasmid.  The fact that a few distinct colonies are red suggests that
> at least some of the plasmids are the correct one.  We've done a
> plasmid dna prep (white colonies, the only ones we can reliably
> produce), and are preparing to sequence it. My best guess is that the
> protein is toxic, and we are selecting for plasmids which eliminate
> expression of the toxic protein.
> Any other ideas?  Similar experiences?

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