Date of Award

Summer 1982

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry & Biochemistry

Program/Concentration

Chemistry

Committee Director

Thomas O. Sitz

Committee Member

James H. Yuan

Committee Member

Robert L. Ake

Call Number for Print

Special Collections LD4331.C45S48

Abstract

When whole cell RNA was separated by high resolution PAG (i.e., polyacrylamide gel) electrophoresis, 5.8S rRNA migrated as three higher mobility intense bands, and three faint bands of lower mobility. The three intense bands represent conformational isomers which migrated as a single band under denaturing conditions on PAG. The three faint bands represent conformational isomers of a minor form of 5.8S rRNA which is elongated at the 5' terminus of the molecule. This minor form migrates as a single band of lower mobility than the major form when electrophoresed on a denaturing PAG. The minor form was determined to have an additional (C)CGAUA sequence on the 5' terminus and appears to arise from either aberrant processing or a subpopulation of 5.8S rDNA genes. For cultured NRK cells, the minor form ranged from 15% of the total 5.8S rRNA in "normal" cells, to 32% in transformed cells. For tissue extracts the yield of minor form was very low in calf liver but approximately 50% in Erhlich ascites tumor cells. Tumor cells contained a higher concentration of the minor form than normal cells, and other characteristics of 5.8S rRNA from tumor cells, such as hypomethylation, were also characteristic of the minor form.

Methylation assays indicated that the compact conformer of the minor form has a low level of ribose methylation in the fourteenth position, while levels of methylation for the other two conformers are considerably higher. Sequencing gels on Erhlich ascites minor 5.8S rRNA, which has a heterogeneous 5' terminus, show that this compact conformer has none of the long terminus, while the other two conformers are terminally heterogeneous. This suggests a correlation between extent of methylation, 5' terminal sequence and conformation.

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DOI

10.25776/1cfx-s196

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