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Biomedical subjects

T C Spelsberg

Publications and source records attributed to T C Spelsberg.

At least 199 records · Page 11Linked to original sources
PubMed1973

Comparison and characterization of nuclear isolation procedures as applied to chick oviduct.

A number of methods for the preparation of chick oviduct nuclei have been compared. Nuclei have been isolated in hypertonic sucrose and citric acid and the product has been characterized with respect to cleanliness, ultrastructure, RNA polymerase activity, RNA integrity, and chromatin composition. The study demonstrates that the choice of oviduct nuclear isolation procedure will depend markedly on the purpose for which the nuclei are required. Thus, nuclei prepared entirely in high-molarity sucrose retain the highest levels of RNA polymerase. Those prepared rapidly in the presence of citric acid retain nuclear RNA in an essentially undegraded state. Finally, a bulk preparation is described which, because of its adaptability and high yield of morphologically intact nuclei using large amounts of tissue, is ideal for use in preparing chromatin. Conditions are described by which isolated nuclei can be stored for up to 6 months and retain their morphology, chemical characteristics, and RNA polymerase activity.

Animals↗
PubMed1972

Early effects of oestradiol-17 on the chromatin and activity of the deoxyribonucleic acid-dependent ribonucleic acid polymerases (I and II) of the rat uterus.

Oestradiol-17beta (1.0mug) was injected intravenously into ovariectomized rats. The earliest detectable hormonal response in isolated uterine nuclei was an increase (10-15min) in RNA polymerase II activity (DNA-like RNA synthesis), which reached a peak at 30min and then decreased to control values (by 1-2h) before displaying a second increase over control activity from 2 to 12h. The next response to oestradiol-17beta was an increase (30-60min) in polymerase I activity (rRNA synthesis) and template capacity of the chromatin. The concentrations of acidic chromatin proteins did not begin to increase until 1h after injection of oestradiol-17beta and histone concentrations showed no significant changes during the 8h period after administration. The early (15min) increase in RNA synthesis in ;high-salt conditions' can be completely eliminated by alpha-amanitin, an inhibitor of the RNA polymerase II. The exact nature of this early increase in endogenous polymerase II activity remains to be determined, e.g. whether it is caused by the increased availability of transcribable DNA of the chromatin or via direct hormonal activation of the enzyme per se.

Animals↗