Insert size?

Bill Jack jack at
Wed Nov 24 08:08:29 EST 1993

In article <1993Nov23.100030.9607 at>, przemko at
(Przemko) wrote:
> Hi out there!
> I have a question that will probably prove that I slept on my
> undergrad. Anyway, here it goes. Why it is so difficult
> (down to impossible) to clone large fragments of DNA into plasmid
> vectors. Practically, anything above 10kb is very difficult
> to clone. If, on the other hand one would use a phage (or even
> better: a cosmid) the problem seems to be gone. In fact it becomes
> quite opposite: small fragments are difficult to clone. My problem
> is that ColE1, the grandaddy of all plasmids is about 100kb long.
Am I missing something here? The ColE1 I know and love is 6646 bp (genbank
accession number J01566). This doesn't solve your problem, but may put it
in a different perspective. I concur with the suggestions from Hodge and
Sutcliffe. Good luck.

Bill Jack
New England Biolabs
Beverly, MA  USA
internet: jack at

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