Activation of osmium ammine by SO2-generating chemicals for EM Feulgen-type staining of DNA
Vázquez-Nin, G.H.; Biggiogera, M.; Echeverría, O.M.
European Journal of Histochemistry Ejh 39(2): 101-106
1995
ISSN/ISBN: 1121-760X PMID: 7549012 Document Number: 452984
We present herein an improved method for the use of osmium ammine in a Feulgen-type reaction for specific staining of DNA at EM level and an analysis of its Schiff-type reagent behaviour. The activation of osmium ammine to a Schiff-type reagent (so far routinely performed by bubbling with gaseous SO-2) can be accomplished by adding SO-2-generating, chemicals as for light microscopy. When used after HCI hydrolysis on epon or acrylate sections, activated osmium ammine behaves like a Schiff-type reagent, and the DNA staining can be selectively and completely abolished by aldehyde blocking agents. This preparation has the advantage of eliminating the use of gaseous SO-2 thus rendering the technique more widely available to laboratories which cannot handle gas cylinders containing SO-2. We recommend the use of osmium ammine in 8N acetic acid and 40 mM sodium metabisulfite for 1 h at 37 degree C for epon sections, and in 0.2N HCI and 0.2M metabisulfite for 30 min at room temperature for acrylate sections.