Slow DNA samples

Peter Ellis pjie2 at cam.ac.uk
Wed May 10 03:41:56 EST 2006


TR wrote:
> Hallo everybody,
>
> Lately our DNA fragments seemed to be shorter than they should. It
> turned out that our DNA samples are running slower that our markers!, from
> the very begging of the run (see photograph at *
> http://webpages.ull.es/users/cglez/CQSPB/gel.jpg*<http://webpages.ull.es/users/cglez/CQSPB/gel.jpg>,
> the markers are in the central lane).
>
> Any idea what the cause may be?

Can hardly make out anything from that picture, it's so blurred.  It doesn't 
seem to be a picture of your DNA *or* your marker, rather a picture of the 
loading dye during running.

So the most obvious answer for that picture is simply that the marker 
contains a different loading dye.

If you're certain it contains the same loading dye, then there's something 
in your loading buffers which is affecting the electrochemistry of the dye 
and/or your samples.

Peter 




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