Ligation mystery

[Chris Boyd]

ER at total.net wrote:
: christoph.kruell at t-online.de (Christoph Krüll) wrote:
(big snip)
: >
: >I Made this experience, too. Even double digested Vectors with non
: >compatible ends religated. I investigated this further, the vectors
: >religated as head to head dimers. So, even with blue white screening
: >they led to false results, because this head to head dimers resulted in
: >white colonies, of course.

There is a wealth of published data saying you can't have head-to-head
plasmid dimers because large inverted repeats are inviable in E. coli. 
Perhaps you mean head-to-tail dimers, or some rearranged construct.

: Can you have two or more origins of replication on a single plasmid
: and have it successfully replicate in a bacterium?
: -ER

Yes.  It is well documented.  Normally the copy number is that of the
highest copy number origin, and the other origins are switched off.

Best wishes,
--
Chris Boyd                       | from, | MRC Human Genetics Unit
chrisb at hgu.mrc.ac.uk             |  not  |  Western General Hospital
http://www.hgu.mrc.ac.uk/~chrisb |   for |   Edinburgh EH4 2XU, SCOTLAND