Northern blot - detetion (help!) - (Feb/28/2006 )

Does anyone know what substrate gives black bands in Northern blot detection? A post-doc before me did a Northern and his blots have black/greyish bands. I'm only familiar with NBT/BCIP detection (DIG-labelled probe; AP-conjugated antibody), chemoluminescence and radioactive labelling of probes (the ladder would give black bands but I'm sure he didn't use radioactivity nor did he use chemoluminescence because he wouldn't have blots but x-rays). I would greatly appreciate anyone's input/help! Thanks

Pat

hem... please forgive me if you think my answer is not relevant, but in northerns, usually using radioactivity, the film is sensitive to radioactivity and the emulsion on it turns altered and gets black in revealing solution...

I also did my northerns with radioactivity on a phosphoimage-plate and then a phospho-imager/scanner "reads" the plate and gives a digital photo in which the bands appear gray or black, depending on the signal and on your software.
It could have also been a rontgen-film.
And there are a lot of commercial-staining methods available. You could try searching on the biocompare website.

Thanks for your input guys. I spoke to my supervisor and she assured me that in no way did this guy use radioactivity because she would be the first person to know about it since all the radioactive material orders go through her. This ex postdoc left no protocols, his lab books are a total mess and hence my frustration with this whole issue. Thanks again and if you have any other suggestions, please keep them coming

could have been hrp, dab, Ni.