Cured ABI373

j.r.sayers j.r.sayers at
Mon Jan 29 09:50:51 EST 1996

Hi All Autosequencers,

Our fast fading gels problem has been cured!

A couple of weeks back I reported having had an awful problem with 
fading ABI 373 runs. As follows;

Problem:  bases 1-150 reasonable intensity, rapid fall off (to junk) 
which sometimes picks up again (intensity increases) after ca 500 bases. 
Chemistry is dye terminators/Taq or TaqFS.

Our attempts to solve this have been extensive, basically after a lot of 
changes of kits reagents etc it appears to be a hardware problem or 
possibly a plate problem as we did the definitive expt. which was to run 
2X samples, run half on our machine and half on one over the road. Guess 
what, over the road the samples ran perfectly. Our machine produced the 
usual fall off and rise. We then used ALL reagents from the other dept, 
ie water, buffers, dyes etc on our machine with crap results again. So 
unless it is something washing off our plates in a wave...  We had been 
running the system perfectly well until November when we had a new laser 
fitted. Since then the results have been as described or worse with loss 
of tracking etc. Have you ever come across this before.

SOLUTION:  ABI Engineers found that the stage was slightly out of 
alignment which had caused low signals and the fade-out problem. The 
stage was fixed and, well, we have never had such STRONG signals! So if 
this happens to you...... call ABI.

Cheers, and thanks for all the suggestions from various netters 
regarding dirty plates etc...


Jon R. Sayers (Lecturer in Molecular Medicine)

////////////Email j.r.sayers at

		University of Sheffield
		Dept. of Medicine  & Pharmacology
 	Section of Molecular Medicine
  Royal Hallamshire Hospital
  S10 2JF

Tel:  +44 114 271 2327(direct)
Fax:  +44 114 271 2882


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