forsburg at molbiol.ox.ac.uk forsburg at molbiol.ox.ac.uk
Wed Jul 21 09:53:07 EST 1993

In article <1993Jul21.114015.10340 at ulci20.unil.ch>, vjongene at isrec-sun1.unil.ch (Victor Jongeneel) writes:
> Claus Jorgensen (claus at tamarin.demon.co.uk) wrote:
> : In article <9307130039.AA17665 at cscgpo.anu.edu.au> Klaus.Matthaei at anu.edu.au writes:
> : >Although P32 PCR goes without a hitch (i.e. clean
> : >block), when S35 is used the block inside the wells (but nowhere else)
> : >becomes contaminated (200-500cps) if either of these tubes is used.  Our
> : Thanks for bringing this subject up.
> : Your theory about volatile S-35 getting through the tube walls can explain
> : the problems we have encountered in our lab with S-35 PCR.  
> I don't have specific suggestions as to a decontamination procedure, but
> both of you may want to check 33P as an alternative to 35S for thermal
> sequencing.  It behaves like 32P chemically (i.e. no oxydation problems,
> high Km for DNA polymerase) but emits beta particles with an energy similar
> to 35S, giving similar quality sequences.  I am willing to bet that 33P

	I got worried after all this and checked our PCR block
with a Geiger, since I have been doing a fair amount of PCR sequencing.
I havent picked up any particular contamination, much less for
example than found in a centrifuge that is used to routinely spin down
the samples (capped of course).  I am using standard
0.5 ml tubes, not special thin-walled ones or anything.  Does
anyone else find that contamination is NOT a problem?
Incidentally thank you for the tip re. 33P.

forsburg at molbiol.ox.ac.uk

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