Neue Kriterien zur Beurteilung isolierter Zellkerne

Abstract

Nuclei, isolated by a modified Behrens'' non-aqueous technique, were subjected to electron microscopy as a test of purity. The morphological observations are in good agreement with analytical and enzymic data. Nuclei were characterized by their RNA: DNA ratio, and by measuring the activities of marker enzymes; some implications are discussed, which result from such experiments with nuclei. The results indicate a high degree of purity of nuclei isolated from rat liver and pig kidney. DNA, prepared from isolated nuclei, was found by several physico-chemical criteria to be in the native, double-stranded state. Determinations of specific activities of enzymes versus the DNA content of nuclear fractions as well as the extractability of enzymes from isolated nuclei are presented as 2 new criteria, which further confirm the validity of enzyme localization in nuclei. The use of the criteria described in this paper is not restricted to non-aqueous nuclei but may be applied for the evaluation of nuclei obtained by any of the different isolation techniques. The enzymic data obtained with isolated nuclei permit some conclusions as to the existence of metabolic spaces in the nucleus.