A Cytochemical Study of the Feulgen Nucleal Reaction

Publisher Website
Google Scholar
Abstract
The Feulgen reaction may be considered as occurring in 2 steps: l)The splitting of the linkage between the purine bases and the desoxypentose of the nucleic acid by means of milk acid hydrolysis, and 2) a chemical reaction between the aldehyde groups thus formed on the sugar, and the Schiff reagent (decolorized fuchsin) resulting in the synthesis of a new dye compound. With increasing degree of hydrolysis beyond a certain optimum, the intensity of staining in the nuclear chromatin of cartilage nuclei, fixed in Carnoy''s acetic alcohol, decreased. This may have 2 explanations (Bauer): (1) continued decomposition of that part of the nucleic acid molecule remaining after the purine bases have been split off; or (2) destruction of the protein-nucleic acid linkage allowing the latter to diffuse from the chromatin. It was detd. to follow photometrically, nucleic acid bases by means of u.-v. absorption, desoxypentose by measuring the amt. of dye produced by the Feulgen reaction performed in the manner described by Stowell, and phosphoric acid by over-staining with methyl green and removing most of the dye not chemically combined by prolonged washing in absolute isopropyl alcohol. Comparing the curves obtained by plotting extinction for each of the above factors vs. time of hydrolysis, it was found that during an hydrolysis which is optimal for production of the Feulgen nuclear color, the change in the nucleic acid molecule involved only the removal of half the total base content (presumably purine), and that overhydrolysis leads to the destruction, or preferably loss from the nuclei of all 3 components of the nucleic acid molecule. Fixatives containing chromic acid fix material in such a way that histones are not readily removable and therefore the material does not show a sudden loss of staining with increased hydrolysis. The quantitative determination of desoxypentose nucleic acid by this method may be feasible.
Keywords

This publication has 1 reference indexed in Scilit: