supercoiled DNA migration in agrose ?

Martin Kennedy cytogen at
Sun Dec 27 03:37:05 EST 1992

In article <1992Dec23.111137.24858 at>, chai_z at writes:
> Hi,
> 	Several batches of M13 RF DNA of mine have been cut by EcoRI or SmaI,
> etc. and then electrophoresized in agrose gel. Uncut DNA (supercoiled) of some
> batches migrated faster than the cut one (linear), while the others slower.
> Most likely, some batches of my DNA were nicked (open circular). Could any one
> tell me the correct agrose pattern of supercoiled, open circular and linear DNA?
> or tell me where to refer to?
> Thanks in advance.
> Zhonglin Chai 

Some of your bands could be "miniphage" rather than various forms of cut/
uncut RF etc.  M13 throws off deleted derivatives (or miniphage) at a 
significant frequency.  They lack the multiple cloning and universal primer
site hence don't interfere with cloning or sequencing, but they can make it
hard to interpret M13 digestion patterns.



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