Autoradiography: "Hole in the middle of Southern Bands"

[Johan de Boer]

> This was recently posted to bionet.molbio.methds-reagnts:

> + Here's a weird problem: recently we have started seeing empty centers to
> +intense bands in our PCR-Southerns (amplify, blot, probe with internal
> +fragment, autorad).  Previous months of blotting never showed this.  Now
> +past 2 weeks, several blots have it.  Sometimes only in certain lanes of a
> +single blot, sometimes all.  Sometimes appears as a clear area in the lane
> +(2 sides of band are hot), other times it's a "doughnut".

>   I'm convinced (as at least one other poster was) that this was actually an
> autoradiographic/photographic effect.  That is, the Xray film used is
> normally turned black from exposure to 32P betatron emissions (after the
> film is developed.)  But in cases where there is a very hot "band" it can
> actually disappear off the film -- or even be a clear band in grey or
> black background.
>   So I'm cross-posting this to sci.chem in the hopes of getting the details
> of the photochemical reactions going on here.  Presumably a certain amount
> of energy causes the silver salts in the film to convert to a non-soluble,
> black form, but above a certain amount of energy the non-soluble products
> convert again into some (new?) soluble form.

Isn't that called solarization?

Johan de boer