Age-related changes in chromatin of liver cell nuclei of different ploidity (original) (raw)
Age-related analysis of EcoRI generated satellite DNA-containing chromatin of rat liver
IUBMB Life, 1996
EcoRI digestion of nuclei and their subsequent lysis with EDTA solubilizes 45% and 36% of chromatin DNA from the liver of young (18+2 weeks) and old (100+5 weeks) rats, respectively. After hybridization with 185 bp rat satellite I DNA, these soluble fractions are found to be enriched in specific DNA sequences such as satellite DNA. Besides regular repeat pattern, a major portion of the satellite chromatin forms higher order organization Digestion kinetics confirms condensation of satellite DNAcontaining chromatin similar to that of bulk chromatin in old age. Furthermore, densitometric scanning of the slot-blot of soluble chromatin fractions reveals loss of satellite DNA in the okL However, an increase in the linker histone HI and its subfraction HI ° in the satellite DNA-emiched fraction of chromatin from old rats suggests greater compaction. These results provide the first evidence that the satellite DNAcontaining chromatin differs in the liver of young and old rats.
Nuclease susceptibility of the rat liver satellite DNA-containing chromatin decreases with age
Molecular and Cellular Biochemistry, 1997
Nuclease susceptibility of the satellite DNA-containing chromatin of the liver of young (18 ± 2 weeks) and old (100 ± 5 weeks) rats was analysed using nick-translated rat 185 bp satellite I DNA fragment cloned in pBR322. With increasing concentration of DNaseI and micrococcal nuclease (MNase), multimeric forms of the satellite ladder gradually disappear in both the ages. The rate
Mechanisms of Ageing and Development, 1988
The amount of spontaneous damage in the DNA of rat liver cells was measured by using the alkaline elution assay. An age-related increase of approximately 700 detectable alkali-labile sites (80%) was found for rat parenchymal liver cells; cells from 6-month-old rats contained approximately 900 alkali-labile sites per cell while cells from 36-month-old rats contained approximately 1600 alkali-labile sites. In contrast to the situation with the postmitotic parenchymal liver cells, no age-related increase in the number of alkali-labile sites was found for the non-parenchymal liver cell fraction, which has a higher mitotic activity. These results support the hypothesis that aging takes place predominantly in postmitotic cells.
Organization of internucleosomal DNA in rat liver chromatin
The EMBO Journal, 1983
A detailed analysis of the length distribution of DNA in nucleosome dimers trimmed with exonuclease HI and S1 nuclease suggests that the previously described variation of internucleosomal distance in rat liver occurs, at least for a subset of the nucleosomes, by integral multiples of the helical repeat of the DNA. Results obtained upon digestion of chromatin with DNase H further suggest that lengths of internucleosomal DNA are integral multiples of the helical repeat of the DNA plus-5 bp. Restraints imposed by these features on the arrangement of nucleosomes along the fiber are discussed.
Experimental Cell Research, 1970
In the present study, epithelial cells from mouse kidney (primary monolayer cultures) were used. These cells showed large variations in local cell density in the monolayer. Proliferative activity and cytochemical prop&ties of nuclear chromatin could thereby be studied on cells in the same monolayer and tissue culture medium as a function of cell density. The following observations were made: 1. The cell proliferation decreased dramatically with increasing local cell density in the monolayer. No proliferative activity at all was observed when the local cell density exceeded 150 000 cells/cm*. Yet in small areas of the monolayer the cell density could increase further (up to 250 000 cells/cm*) as a result of cell crowding. This process of "non-proliferative cell crowding" was associated with morphological alterations of the crowded cells. 2. The observed decrease in proliferative activity was found to be a result of an inhibited initiation of DNA synthesis, leading to a decrease in the proportion of cells going through the S and G2 periods. When cell proliferation had ceased, the cells were arrested in Gl. 3. An annroximate linear relationship existed between the size of the glass surface area occupied by a cell and the cellular growth rate. 4. In connection with the process of "non-proliferative cell crowding"! the cytochemical properties of the nuclear chromatin changed. The capacity of the chromatm to bind acridine orange (AO) decreased 40 % and the resistance to heat-denaturation increased in the chromatin. These chromatin changes which are similar to those occurring in connection with spermiogenesis and erythropoesis and of a reverse kind compared with those occurring upon growth stimulation of differentiated cells, may reflect an "inactivation" of the chromatin related to cell growth inhibition or cell differentiation.
Isolation and properties of structured chromatin from Guerin ascites tumour and rat liver
European journal of biochemistry / FEBS, 1976
The method proposed by Hancock for isolation of structured chromatin from tissue culture cells is modified and used for isolation of chromatin from Guerin ascites tumour and rat liver. Micrococcal nuclease digestion patterns and thermal denaturation of these chromatins are studied and compared wiith those of chromatins prepared by precipitation and extraction with salts (salt chromatins). In contrast to the multiphasic melting profiles and salt chromatins, the structured chromatins exhibit relatively homogeneous denaturation patterns under a variety of conditions, suggesting thhat their DNA is uniformly stabilized by histones and there are no free independently melting DNA stretches. Digestion of structure of the deoxyribonucleoprotein is intact. No discrete fragments are formed upon digestion of salt chromatin.
Chromatin degradation in isolated nuclei of normal and transformed baby hamster kidney cells
Cancer research, 1985
In a transformed cell line, derived from baby hamster kidney cells by treatment with ethylnitrosourea, degradation of DNA in isolated nuclei by endogenous nuclease was studied. Compared to the nontransformed cell line, the nuclear DNA of the transformed cells was found to be degraded to a much greater extent. This was reflected by a markedly lower proportion of DNA attached to the nuclear protein matrix in the transformed compared to the nontransformed cells. These observations can be accounted for by assuming that the chromatin of the transformed cell line has a conformation different from that of the nontransformed cells.
Virchows Archiv. B, Cell pathology including molecular pathology, 1988
In order to quantify the changes in nucleolar and nuclear volumes and in chromatin condensation produced during proliferative activation we have carried out morphometric studies on hepatocyte nuclei during rat liver regeneration using electron microscopy. To minimize the artefactual effects produced by fixation on subcellular structures we have fixed the livers by perfusion with glutaraldehyde. The mean values for the nucleolar and nuclear volumes were progressively increased until 28 h after 66% partial hepatectomy. The maximum values raised for the nuclei and nucleoli at this time were 3 and 4.28 times, respectively, those of controls. Later, nuclear and nucleolar volumes progressively declined. Two waves of diminution in nuclear electron-dense material were produced after hepatectomy. The first occurred between 0 and 12 h, with minimum values 1.34 times lower than those from control animals at 8 h. The second occurred between 12 and 28 h, with minimum values 2.56 times lower than...