NA45 Paper DNA extraction problem

[Frances Hannan Zoology]

grieger at matt.ksu.ksu.edu (David M Grieger) writes:

>I had my student try to purify a 200bp fragment from a gel using the NA45
>paper technique, recently discussed here on this news group.  After she did
>the hi-salt washes and the EtOH precipitation (+glycogen), there was no
>normal pellet but a nonaqueous "bubble" in the bottom of the microfuge tube.
> After adding TE and doing a second EtOH precipitation the same result
>occured.  Could this result from carry over from the hi-salt washes?  Any
>thoughts on this problem would be appreciated.  Thanks.

I have never seen such a bubble in any of my NA45 fragment preps. I use 
linear acrylamide as a carrier so perhaps this is due to the glycogen. I 
have heard of the same problem from another person who also used glycogen 
in this protocol. Did your student do a phenol or phenol/chloroform 
extraction step before precipitating? It is possible that the bubble could 
be bits of agarose or shards of NA45 which would normally spin out during 
an extraction.

Hope this provides some clues to you, Frances
-- 
Frances Hannan                                       
BILMS, Zoology, Downing St, Cambridge, CB2 3EJ, UK   
Phone (0223)336663, FAX (0223)461954                 
flh at mole.bio.cam.ac.uk