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M H Sarma

Publications and source records attributed to M H Sarma.

42 records · Page 3Linked to original sources
PubMed1976

RNA synthesis in isolated HeLa cell nuclei.

RNA synthesis has been studied in isolated nuclei of HeLa cells. The incubation medium has been optimized for RNA synthesis and the requirements for the presence of specific components previously used by other investigators has been examined. Nuclei isolated by centrifugation through 2 M sucrose synthesize RNA linearly for at least 1 h only at low temperature (25 degrees C). Low molecular weight RNA is found in the supernatant fraction after incubation; this RNA accounts for about 10% of the RNA synthesized. The RNA which remains within nuclei is of high molecular weight and processing of this RNA into molecules of the size of cytoplasmic mRNA does not seem to occur in isolated nuclei. We have studied the effect of an inhibitor of protein-nucleic acid interaction - aurintricarboxylic acid - on RNA synthesis by isolated nuclei. At concentrations below 0.1 mM, this drug does not inhibit RNA synthesis effectively, whereas at concentrations above 0.1 mM it inhibits RNA synthesis by about 80%. In view of the proposed mechanism of action of aurintricarboxylic acid, we suggest that completion of nucleotide chains initiated before nuclei isolation accounts for 20% of the RNA synthesized in our system by isolated nuclei, whereas nucleotide chains initiated during the in vitro incubation account for 80% of the RNA synthesized.

Aurintricarboxylic Acid↗
PubMed1976

Processing of RNA by cytoplasmic extract. Synthesis and processing of RNA by isolated HeLa cell nuclei incubated with cytoplasmic extract.

Nuclei are isolated from HeLa cells by a low speed centrifugation procedure. These nuclei can carry out RNA synthesis at 30 degrees. The effect of cytoplasmic extract on the transport and processing of RNA is measured. In the presence of cytoplasmic extract the precursor to 4S RNA is processed to 4S RNA and an RNA species OF 7-9S is transported outside the nuclei.

Cell Extracts↗