Chromosin, a Desoxyribose Nucleoprotein Complex of the Cell Nucleus

Abstract

Nucleoproteins can be extracted and isolated from the nuclei of animal and plant tissues by the same procedure, somewhat modified, that is effective in preparing the nucleoprotamines of sperm (1, 2). In this paper the preparation of nuclear nucleoproteins from animal and plant tissues and from bacterial cells is described and some results of an investigation of these substances are given. Nucleoproteins are also present in the cytoplasm of animal and plant tissues. It is an important step in the isolation of nucleoproteins to separate those occurring in the nucleus from those of the cytoplasm. This can be accomplished in two ways: by chemical procedures of fractionation and by methods in which well formed nuclei or chromosomes are isolated from the cytoplasm before extraction is begun. These two methods of preparation have in practice much in common. Although many bacteria may not have distinctly formed nuclei, they do have both the nucleoproteins found in the nuclei and those found in the cytoplasm of cells in which the distinction between nucleus and cytoplasm can be made morphologically. In this paper the preparation of what might be called the nuclear nucleoproteins of bacteria is described and it will be seen that this preparation was made possible by the experience gained by working with animal and plant ceils. Although this paper is concerned primarily with nuclear nucleoproteins, the first steps in the isolation of cytoplasmic nucleoproteins are outlined.Animal and plant tissues in general have not appeared to be favorable material for investigation of nuclear constituents because in so many tissues nuclei are embedded in relatively large masses of cytoplasm. For this reason Miescher (8), Kossel (3), and other leading investigators preferred to work on sperm, cells in which there is little cytoplasm. The thymus gland is an animal tissue in which nuclei form an unusually large fraction of the total volume, and on the nuclear constituents of the thymus there are the important investigations of Lilienfeld (27), Huiskamp (7), Bang (7a), Hammarsten (22), and others. These investigators did not use strong acid and alkali, the reagents by means of which the somewhat disintegrated nuclear constituents of sperm had been isolated; instead, in extractions from the thymus nothing more drastic than distilled water was used. The consequences of this mild treatment were that nucleic

Stathmin/Op18 Phosphorylation Is Regulated by Microtubule Assembly

“…KE 37 cells isolated centrosomes were prepared as described (Bornens and Moudjou, 1999). Nuclei devoid of any cytoplasmic contaminant or of nuclear envelope, but containing the native distribution of perinuclear and perinucleolar condensed chromatin (Bornens, 1968), were obtained from KE 37 cells treated with 1% citric acid (Mirsky and Pollister, 1946). Each nucleus corresponds to a unit of chromatin.…”

“…We wondered whether chromatininduced phosphorylation of stathmin/Op18 could be an indirect effect due to stabilization of MTs by the mitotic chromatin beads. We therefore used nuclei from somatic cells treated with citric acid (Mirsky and Pollister, 1946), which have been shown to be devoid of nuclear envelope and of centrosomes (Bornens, 1968; Figure 8B, ␥-tubulin staining) and can therefore be considered as units of chromatin (see MATERIALS AND METHODS). We incubated them for 1 h in a high-speed mitotic Xenopus egg extract at several concentrations (from C1: 7.5 ϫ 10 3 nuclei/l to C3: 1.1 ϫ 10 4 nuclei/l) corresponding to the physiological DNA/cytoplasm ratio in an egg.…”

Intracellular Localization of Type 4 Adenovirus

“…The technique involving mechanical disruption of cells and repeated washings with sucrose solutions was adopted after preliminary studies with adenovirushifected HeLa cells showed that this procedure gave better results than other methods tested. Several other techniques were discarded when it was found that the yield of nuclei was too low or that adenovirus was inactivated during the procedure (18)(19)(20)(21). The method employed was originally described by Schneider and Hogeboom (13) and used successfully by Ackermann and Kurtz (22) and Gray and Scott (14) in studies of the intracellular localization of herpes simplex virus in the liver of the mouse or chick embryo.…”

Problems in microbial genetics

“…The total absence of all other components is not readily established, although none can be detected with available methods. The criticism of Mirsky and Pollister (1946) should be noted, however. The further chemical characterisation of the transforming principle is one of the most urgent problems of present-day biology, since it behaves like a gene which can be transferred by way of the medium from one cell to another.…”