HELP! -- Protecting DNA on a transilluminator?

David Micklem drm21 at
Mon Jul 7 14:40:14 EST 1997

In article <33c12035.5223697 at>, Vern Shellman wrote:

>I am having problems ligating my DNA fragments cut out of a gel.  I
>get variable results that seem to relate  to how long it takes to cut
>out the band.  The fastest I can see and cut out a band is about 15
>seconds and by then I suspect there is already significant UV damage.
>Is there any way to protect my DNA during UV exposure?

Use a LONG-WAVE UV transilluminator! If you haven't got a big long-wave
box, then use one of the little hand-help ones. (Of course, you might be
using long-wave already, in which case...):

I suppose you might gain a little time by attenuating the UV with
something, if you can't get hold of a long-wave source (but it'll be harder
to see the bands). 

If you are purifying a LOT of DNA, and run the gel with a little ethidium
bromide in the gel and buffer, then you can often see the bands in daylight
against a white background. (This may also work with post-staining the gel,
but I haven't tried).

Alternatively, I think that the FAQ has methods for staining DNA without
using Ethidium bromide and UV - although it is less sensitive. The method
uses methylene blue IIRC.


D.R.Micklem,                                Time flies like an arrow... 
Wellcome/CRC Institute,            Fruit flies like a banana.       
Cambridge CB2 1QR, UK               Email:drm21 at
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