For the past couple of months, a group running lots of GeneScan has been
seeing greatly reduced signal intensities of their marker bands, but only
when run on 2 particular instruments. If we take the same samples, and load
them on either of 2 other instruments, in a different room, different
floor, the signal intensities are normal.
Sequencing runs on all the instruments, using primarily Big Dye
terminators, look beautiful and normal.
We have taken a gel from one machine mid-run, and moved it to one of the
other sets, and seen the change of intensities.
We have loaded the same batch of samples and demo standards on parallel
runs on the same machines, and seen the different intensities.
We have checked:
plates, gel mixes, buffers, formamide,
PE-biosystems has changed:
lasers, power supplies, CCD cameras, other optical components.
This problem is starting to feel like voodoo or black magic.
Unfortunately, I'm a muggle scientist, and not a wizard, so the solution
still eludes me. Can any of you suggest things we might be overlooking, or
should check differently?
I appreciate your support, as always.
Mary Kay Dolejsi, Ph.D.
Manager, Biotech lab
marykay@fred.fhcrc.org
phone: 206-667-4197
fax: 206-667-6497
Mail address:
Fred Hutchinson Cancer Research Center
1100 Fairview Ave N., B1-080
PO Box 19024
Seattle, WA 98109-1024