THERMAL ANALYSIS OF POLYANION METACHROMASY: TEMPERATURE EFFECTS ON STAINED CELLS, TISSUES AND MODELS
Metachromasy of toluidine blue-stained materials was examined at 5-95°C visually and 30-70°C microspectrophotometrically. Cells and tissues provided sites of acid mucopolysaccharides and nucleic acids, which were also prepared as films and droplets. As in similar studies of aqueous solutions, metachromatic ratios were inverse, linear, reversible functions of temperature, with the possible exception of deoxyribonucleic acid. An aqueous mounting medium (gelatin) supported maximum excursions of metachromasy during heating and cooling, although reversible loss of metachromasy occurs to lesser degrees in conventional media. Removal or denaturation of cartilage matrix protein merely increased over-all metachromasy; slopes of thermal plots were unchanged. All evidence suggests that metachromasy is not a fundamentally different phenomenon in solutions and solid systems. Temperature studies emphasize the role of structured water in metachromasy, interaction of water and other solvents and particularly solvent dielectric constant in relation to dye-dye interaction. The limited literature on temperature and biologic staining is reviewed.