Why probe hybridizes to vector?

[gaterman at mzdmza.zdv.uni-mainz.de]

In article <biolc4-020795165223 at mac-918.sr2-building.uh.edu>, biolc4 at jetson.uh.edu (Wenfu) writes:
>
>When I was using isolated DNA fragment( I am sure no any vector sequence in
>it)
>to probe digested plasmids, I found my probe hybridizes to the vector.
>This kind of thing happen to me several times when I was doing the similar
>thing. Although it did not matter for my results, I am really curious 
>about the reasons for.
>Any idea would be appreciated.



1 if the probe is too long,  almost any  hibridization will cause a signal
probe size should be small (< 200bp).  Normally , this can be achieved by
using some oligo-priming kit or by sonicating the probe.
2 check your hibridizytion conditions
sgg