Distinct bands in restriction dig. of genomic DNA

[Markku.M Jeltsch]

Occasionally when I digest genomic DNA (e.g. tail DNA from 
transgenic mice) I observe a distinct band in the pattern that looks 
otherwise completely digested. Does anyone know what is the reason of
this? 
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Markku Michael Jeltsch           MOLECULAR/CANCER BIOLOGY LABORATORY
Apollonkatu 19A14                THE HAARTMAN INSTITUTE
FIN-00100 Helsinki               UNIVERSITY OF HELSINKI
e-mail: jeltsch at cypress.csc.fi   P.O.B. 21 (HAARTMANINKATU 3)
phone: -358-0-434 6436 (work)    FIN-00014 HELSINKI
       -358-0-454 3418 (home)
fax: -358-0-434 6448 (work)
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