35-S in thermal cycling: contamination problems

[John Nash]

In article <2j5asj$svd at mserv1.dl.ac.uk>,
Andreas Vogel  <vogel at urz.unibas.ch> wrote:
>Dear netters out there,
>
>I'm a new user and I don't know if the problem has been discussed before on the
>methods-and-reagents bulletin board, if it has been, please hint me to where I
>can find the relevant information. The PROBLEM:
>
>35-S IS UNSTABLE IN THERMAL CYCLING AND CAUSES RADIOACTIVE CONTAMINATION OF
>PCR CYCLERS AND, PROBABLY, THE LABORATORY ENVIRONMENT.
>(No joke. I've been trying to clean PCR machines (two) for hours without
>success.)
>
>The QUESTION:
>
>HOW CAN YOU PREVENT CONTAMINATION OF CYCLER AND LAB?
>(Amersham say using 33-P, as it has been suggested by a company that sells PCR
>cyclers, wouldn't help as it is also unstable in thermal cycling. Would certain
>reaction tubes help preventing contamination? Are there additives that help?)
>
>If you have any experience that you can share, please do share... I'd appreciateit.
>
>Andreas Vogel

Coincidentally, I just spoke to our Perkin-Elmer rep about this about
2 hr ago.  He says that this happens when radioactive H2S is produced
when the dATP-alpha-35S is heated, and that contamination depends on
the type of tube used. (My question: Won't the volatile H2S-35 pop out
when *any* tube is opened?)

He also said that Perkin-Elmer tubes won't contaminate my (new) 9600
PCR machine.

[I am yet to be convinced.  I'm sticking to Sequenase!]  Please tell
me more about 33P's alleged instability with thermal sequencing.



-- 
John Nash                           (nash at nrcbsa.bio.nrc.ca)
Institute for Biological Sciences,  National Research Council of Canada,
                 Yet another Aussie-in-exile ;-)
      *** Disclaimer:  All opinions are mine, not NRC's! ***