autorad mystery

James J. Campanella jjc4 at po.CWRU.Edu
Wed Aug 9 13:45:55 EST 1995


I seem to have run into a weird problem which I am having trouble
explaining. The last 3 DNA blots that I have exposed to film have
shown only a faint signal on the film. This is not necessarily 
strange except that each blot has had a signal of ~1000 cpm; in
my experience that is more than enough to give at least some
signal overnight, but I am getting only a barely discernable
background. The probes are P32-labelled and the blots newly
hybridized. There seems to be nothing wrong with the developing
soln because other labs are not having problems. We are using
FujiRX film, but I have no idea whether that's a contributing factor
or not. 
Anyway, to sum it up, this seems to go against the laws of nature.
If you expose film to a radioactive source, it should darken--
even if the darkening is just background crud and not a decent
Does anyone out there have the faintest idea what might be going
on here? I am nearing my wits end. Thanks.

Jim Campanella
Case Western University
Biology Dept.
"Sometimes the Road less travelled is less travelled for a
reason."   - Jerry Seinfeld

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