Polyacrylamide gel electrophoresis query

[Timothy R Jackson]

we have recently noticed in our lab that a significant amount of, what 
appears to be, precipitation of small fragments (<300bp) out of our gels 
onto the glass plate that they're fixing on.  our fragments are 33p 
labelled and we've noticed that the longer you fix a gel the worse the 
problem (hotter plate than gel!)  a 0.4mm gel only needs to fix for a 
minimum of 20min which does not cause much of a problem but fixing 
overnight, for instance, seems to result in massive precipitation.  we 
are getting away from fixing all together - the drying time is slightly 
longer and no difference in the results (and less waste too!!)

Tim Jackson
Dept. of Zoology
University of Guelph
Guelph, Ontario
CANADA

: I was wondering if anyone could give me a concise answer to a 
: query I have regarding polyacrylamide gel electrophoresis 
: methodology.  

: The question is this ; when fixing gels with acetic acid & 
: methanol, what is happening ? (How does this fix 
: oligonucleotide bands ? By precipitation ? & are small oligos 
: likely to be leached out during this process ?).

: Many thanks in advance for your help.

: Mark.