Opinions needeed about phosphoimagers

pmiguel at bilbo.bio.purdue.edu pmiguel at bilbo.bio.purdue.edu
Thu Jun 24 12:45:02 EST 1993


In article <kvist.17.740818894 at lbiok-1.oulu.fi>, kvist at lbiok-1.oulu.fi (Ari-Pekka Kvist) writes:
>Hi 
>
>We are planning to buy phosphoimager apparatus to our lab but we 
>don't know yet which one. If you have any experiences about those 
>machines I would be very happy to hear them. Is Molecular Dynamics
>better than BioRad? Is there some new machines coming? How sensitive 
>they REALLY are (does C-labeling work)?....
>
>Ari-Pekka Kvist
>apk at phoenix.oulu.fi
>
  Our department now owns a Molecular Dynamics phosphoimager and I saw the 
BioRad phosphoimager demonstrated.  [We only got the 8x10 scale set-up
not the 14x17.]  I didn't like the BioRad phosphoimager because I only use 
radioactively labelled probes and the BioRad was geared to read both 
luminescent and radioactive signal.  This sounds like a benefit and to some 
it would be.  But it meant the screens had to be protected from visual 
light.  
  I would have much prefered the Protein Database machine because it ran 
off a SPARCS station, rather than a PC.  But it was more expensive.
  Also I think that the claims of phosphoimager screens being 10x more 
sensitive than film is a con-job because it doesn't take into account the 
use of intensifying screens.  With 2 screens at -80 oC I doubt the 
phosphoimager is much more than twice as sensitive -- if that.
  The real power of a phosphoimager screen is in its ability to respond 
linearly over 4 logs intensity of exposure.  (This is the Molecular 
Dynamics number.  I thought I remembered the Protein Database rep saying 
they were linear over 7 logs.  Film is supposed to have a linear response 
over only 2 logs.)  But near as I can tell this requires long exposures to 
take full advantage of.  Then the rest is in the software which allows you 
to manipulate dataset to get the best possible "exposure".



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