Quantitative mikrospektrographische Messungen zur Aufnahme von Thionin durch lebende Zellen von Allium Cepa

Abstract

The absorption of the basic thiazine stain thionin was studied quantitatively in relation to pH external concentration, and time of staining. By comparison with previously published measurements with the basic stain acridin orange it seems probable that it is necessary to recognize differences within the group of basic stains with reference to the conditions of their absorption by living cells. The stains thionin (Thio) and acridin orange (AO) resemble one another extraordinarily in their physical characteristics, and there is also no great difference in their dissociation constants for the first proton addition. Yet, whereas with AO the maximum accumulation in the vacuoles of living cells is reached at several pH units below the PK, the absorption of thionin follows the dissociation curve closely. This difference appears to be based on the fact that AO molecules, analagous to methylene blue, are not present in aqueous solutions but only the undissociated basic molecules [AO]+OH and [MB]+OH. On the contrary, with thionin [Thio]-molecules are present in addition to the [Thio]+OH molecules.