Polyamine cytochemistry. Use of a novel o-phtalaldehyde method for visualizing spermidine and spermine. Comparisons to the formaldehyde-fluorescamine method.
o-Phtalaldehyde (OPT) reacts with a number of biologically important molecules, including the polyamines, spermidine and spermine. By systematically varying reaction conditions with respect to temperature, pH, concentration and length of exposure to the reagent, using both model systems and tissues, we have succeeded in constructing a cytochemical OPT-method specific for spermidine and spermine. The method detects cell types known to contain these polyamines, including growing and neoplastic cells. The staining pattern obtained with the OPT method is identical to that obtained with the formaldehyde-fluorescamine (FF) technique recently shown to be specific for spermidine and spermine. In contrast to the FF technique, the OPT method can be used for staining suspensions of isolated cells and may hence be employed in studies using fluorescence-activated cell sorting (FACS). Preliminary such studies show a pronounced decrease in cellular OPT-induced fluorescence, paralleled by a decrease in content of polyamines, after treatment with the polyamine biosynthesis inhibitor alpha-difluoromethylornithine (alpha DFMO). In contrast, cells simultaneously treated with alpha DFMO + spermidine show pronounced increases in their spermidine content and parallel increases in their OPT-induced fluorescence. Availability of methods selectively demonstrating polyamines at the cellular and subcellular level is expected to aid our understanding of polyamine functions in normal growth and cancer.