Nuclei of hemlock (Tsuga canadensis and Tsuga canadensis var. nana) wereinvestigated for the presence of flavanols. Histochemical staining with p-dimethylaminocinnamaldehyde proved to be a highly valuable method yielding a brightblue flavanol coloration for nuclei. There was a significant variation in flavanol deposition(1) among nuclei, (2) at the subnuclear level and also (3) along the chromosomes duringmitosis. The presence of flavanols in nucleoli could not be established probably becausethey were too small, measuring less than 1 \textgreek{m}m in diameter. In contrast to Tsuga, the cellsand nuclei of rootlets from rye (Secale cereale) were totally devoid of natural flavanols.However, externally added flavanols, catechin and epicatechin, were bound to the ryenuclei, while the rather large nucleoli failed to associate with the flavanols. The strong sinkactivity of nucleoplasm and chromosomes for flavanols in Tsuga and Secale indicates aprocess which is apparently widespread even in distantly related plant species. Variationsin chromatin-associated flavanols could to some extent be induced byacetylation/deacetylation of histones, as confirmed in the present study by means of UV-VIS spectroscopic titrations of histone sulphate and chemically acetylated histone sulphate.     «

Nuclei of hemlock (Tsuga canadensis and Tsuga canadensis var. nana) wereinvestigated for the presence of flavanols. Histochemical staining with p-dimethylaminocinnamaldehyde proved to be a highly valuable method yielding a brightblue flavanol coloration for nuclei. There was a significant variation in flavanol deposition(1) among nuclei, (2) at the subnuclear level and also (3) along the chromosomes duringmitosis. The presence of flavanols in nucleoli could not be established probably becausethe...     »