Lambda DNA migration in agarose gels?

[Dr. Duncan Clark]

In article <362F1BF9.3E4F9416 at aki.ku.dk>, Jens Mollerup
<jmollerup at aki.ku.dk> writes
>We have purified lambda ZAP ll DNA with a size of 40kb. Surpricingly,
>when runned on an 0.6% agarose gel this fragment goes as a 20kb band?
>After one cut with a restriction enzyme two bands at approx 20kb
>appears. Does anyone have an explanation for these observations?
>Thanks in advance

Run very slowly overnight without EtBr and post stain. To resolve 40kb
from 20kb you will need say a 20cm long gel and maybe 0.4% agarose.

Duncan

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Duncan Clark
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