hot start beads

[PRASHERD at DELPHI.COM]

Netters,
We have used Invitrogen's HotStart Beads with wonderful results
but they are VERY EXPENSIVE.  Cost is a major concern to us
because we run LOTS of PCR reactions.  At the lowest cost we
can purchase Invitrogen's beads (20,000+) it would still cost
over $41 per 96 PCR reactions for the beads ALONE!!

We are testing the use of paraffin wax (Aldrich) and mineral
oil (used as a softener of the wax following the mixing of the
limiting reagent and the reaction mixture) but have yet to hit
upon a combination that we are happy with.  This approach
requires a fair number of pipetting steps but the cost would be
low.

Invitrogen's beads have the Mg2+ dispersed throughout the bead.
 Is anyone in Netland willing to share their success in
reproducing these kinds of beads?  I have thought maybe they
could be produced by vigorously mixing molten wax and a
solution of MgCl2 with a Polytron homogenizer.  Pipetting this
mix onto a surface (eg. tin foil) might form a bead having the
Mg2+ encapsulated in the wax.  Any thoughts on this?

Whatever hot start technique you use, I would very much
appreciate hearing about it.  If there is sufficient interest,
I will summarize the replies and repost them to this bulletin
board.

Thank you in advance.

Douglas Prasher
U.S. Dept. of Agriculture
Cape Cod , Massachusetts

prasherd at delphi.com