Female rat hearts were maintained by retrograde perfusion under a hydrostatic pressure of 75 cm H2O. The perfused heart had a coronary flow of 8-9 ml/min and a heart rate of 220-240 beats/min. Recirculation of [3H]acetate (2 muCi/ml perfusate) for 20 min was sufficient to label nuclear proteins. Total nuclear proteins were separated into three major classes: (1) 0.14 M NaCl soluble nucleoplasmic proteins, (2) nucleohistones and (3) nonhistone residual proteins. Approximately 88-90% of the (3H)acetate incorporated was found in the nucleohistone fraction. Polyacrylamide-urea gel electrophoresis of the histones indicated that fraction f1 was not acetylated while f3 and f2al were highly acetylated, containing 75% of the total histone radioactivity. Fraction f2b + f2a2 was moderately acetylated contributing 20-25% of the radioactivity. Nucleohistones isolated from myocardial cells showed the same percentage distribution of (3H)acetate in the histone fractions as the whole heart. Acid hydrolysis followed by steam distillation released more than 95% of the acetyl groups from the two major nucleoproteins. These data suggest that the isolated perfused heart may provide a model system to study covalent modification of nucleoproteins under controlled physiological and biochemical conditions.

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PubMedDate not supplied

Cardiac genes and gene databases for cardiovascular disease genetics.

Genes play a very important role in the etiology of hypertension. This paper reviews the current pool of candidate genes for human hypertension. Some of the genes studied in rat models of hypertension are also discussed. The methods for studying the genetics of hypertension are reviewed. A discussion of the role of cardiac gene libraries and gene databases in the characterization of cardiovascular disease is also included. This review is concluded by a discussion on the future role of genomics and cardiovascular gene databases in medical research.

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PubMedDate not supplied

Distribution of a novel nuclear protein in normal and regenerating liver cells.

Monoclonal antibodies to a rat liver nuclear protein (B2, 68 kda, pI: 6.5-8.2) have been established and characterized to localize the distribution of this antigen in nuclear organization. It was demonstrated that this nuclear protein B2 is associated with actively transcribed nucleosomes and the nuclear matrix as revealed by immunogold labelling. In the regenerating liver cell, the immunogold particles are predominantly in the euchromatin as compared to the resting liver cells which are mainly in nuclear matrix and heterochromatin. It was also demonstrated that the incorporation of 32P into the nuclear protein B2 is increased 6-fold in the actively transcribed nucleosomes as compared to the nuclear matrix, as analyzed by two-dimensional polyacrylamide gel electrophoresis. We hypothesize that this nuclear protein may act as an anchorage point either for actively transcribed RNA or for DNA replication. Once this protein is highly phosphorylated, it dissociates from the nuclear envelope and can then dynamically interact with active nucleosomes within the nucleus.

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PubMedDate not supplied

Immunogold localization of a nuclear protein at different stages of the cell cycle in normal and tumor cells.

The interaction of immunogold particles with a specific antigen was used to localize this nuclear protein (Mr 68 kd, pI 6.5-8.2) in fetal liver cells and oesophageal carcinoma cells at different stages of the cell cycle. In interphase hepatocytes, the 68 kd antigen was localized exclusively in the nucleus and associated with both heterochromatin and euchromatin. As the chromatin condensed into chromosomes at later stages of the cell cycle, the 68 kd antigen remained closely associated with them. Similar phenomena were observed in the oesophageal carcinoma cells, suggesting that this 68 kd nuclear protein may be involved in anchoring the actively transcribed DNA and in maintaining the chromosomal architecture during the cell cycle.

Animals↗

PubMedDate not supplied

Organization and modulation of a novel nuclear phosphoprotein during rat spermatogenesis.

The localization and distribution of the B2 nuclear phosphoprotein in spermatogenesis in the rat were studied by immuno-gold electron microscopy. In spermiogenesis, the phosphoprotein B2 was shown to have phase-dependent changes in number and distribution. A temporal increase in synthesis of this protein was observed during spermiogenesis. The high quantity of this protein in the mature sperm head suggests its role in maintenance and organization of DNA.

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