Previous studies in our laboratory have indicated that the nuclei of a number of trees are associated with flavonoids, especially flavan--3--ols. In the present study, three techniques were applied to verify that flavonoids are naturally incorporated into nuclei. These were histochemistry, UV--visible (UV--VIS) titration and laser microdissection. Nuclei from intact seed wings of Tsuga canadensis were isolated from their cells using laser microdissection and pressure catapulting (LMPC). Thereafter, the excised nuclei were stained with p--dimethylamino--cinnamaldehyde (DMACA), which resulted in a blue coloration due to the presence of flavanols. Thus, there is no doubt that the nuclei were, prior to staining, associated with flavanols. The nuclei of the coniferous species Abies lasiocarpa, Cedrus deodara, Cedrus libani, Juniperus communis, Picea abies, Picea orientalis and Pseudotsuga menziessii(Douglas fir) showed a yellow fluorescence typical for flavonols from the beginning of bud break over the entire growing season. However, after the bud--breaking period, the nuclei of all species, except for Cedrus deodara, showed additionally a blue reaction for flavanols. Rather late, in midsummer, blue--stained flavanols in nuclei were found in Picea orientalis. Generally, zeatin intensified the flavanol association with the nuclei. The main components of nucleosomes are DNA and the histone proteins. The nature of their association with the flavonols quercetin and rutin was investigated by UV--VIS spectroscopic titration. The data were evaluated by means of the Mauser (A and AD) diagrams. The results indicate that DNA shows largely no spectroscopically detectable association equilibria under the experimental conditions chosen. However, association (aggregation) equilibria can be observed with rutin or quercetin and histone sulphate in Tris buffer (pH 8.0, 7.4 and 7.0). In phosphate buffer, rutin shows spectroscopically no or only weak association with histone sulphate, in contrast to its behaviour towards quercetin.     «

Previous studies in our laboratory have indicated that the nuclei of a number of trees are associated with flavonoids, especially flavan--3--ols. In the present study, three techniques were applied to verify that flavonoids are naturally incorporated into nuclei. These were histochemistry, UV--visible (UV--VIS) titration and laser microdissection. Nuclei from intact seed wings of Tsuga canadensis were isolated from their cells using laser microdissection and pressure catapulting (LMPC). Thereaft...     »