agarose gel electrophoresis

Kimberley Snowden kcsnowden at
Fri Mar 21 12:50:06 EST 1997

I think it's probably because your gel isn't stained the whole way
through.  If you added Ethidium bromide to your sample before loading
(not that I think you should do this, especially if you want to
isolate the DNA) then the band might look more homogeneous.
Alternatively you could stain for longer or use thinner gels.

arump at (Andreas Rump) wrote:

>Dear Netters,

>I have observed the following phenomenon several times: when I cut 
>out a piece of agarose gel containing a single DNA band and place this
>piece of gel on it's side, then I see two bands. This means, that the
>same DNA moves through the gel on two different levels (x and y, see
>Figure), one near the bottom of the gel and one near the surface. 
>Both bands are discrete, although the slot has been completely filled
>with sample and one would expect that the DNA enters the gel at the
>whole heigth of the gel and would move as one broad band.

>                                         Slot
>      |----------------------------------|  |--|
>      |              x                   |  |  |
>      |                                  |  |  |  Gel, seen from the
>      |              y                   |__|  |  side
>      |________________________________________|

>Has anyone observed the same phenomenon or can explain it?

>Sincerely yours,
>Andreas Rump.

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