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Title: The effect of infection with pseudorabies virus on low molecular weight RNAs in BHK 21/13 cells
Author: Shepherd, Wilma M.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1969
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A general review of the mechanism of translation and a description of the essential components of the translation system are presented. Evidence of changes induced by bacteriophage and animal virus infections at a variety of different points in the host cell translation mechanism are described and the implications of such changes discussed on a theoretical basis. The effect of infection of viruses of the Herpes group on the population of low molecular weight RNAs in mammalian cells is considered in more detail. Reported in this thesis are investigations designed to compare low molecular weight RNAs in non-infected and pseudorabies virus infected BHK 21/13 cells. The three separate approaches used and the results obtained are briefly described below. Molecular hybridisation experiments are reported which indicate that a proportion of the 4s RNA synthesised in pseudorabies virus infected cells, which possesses all the characteristics of tRNA, is specified by the viral genome. The material occupies 0.15% of the viral DNA and corresponds, at most, to four tRNA molecules per DNA. This quantitation is however only an approximation and is subject to several limitations which are discussed. The populations of certain aminoacyl-tRNAs from non-infected and virus infected cells are compared using standard chromatographic techniques such as MAK column chromatography and Reverse phase type II chromatography of aminoacyl"-tRNA, and DEAE cellulose chromatography of T1 RNase digestion products of aminoacyl-tRNA. In all experiments, the preparations from host and virus infected cells are differentially labelled in the amino acid moeity, mixed and subjected to co-chromatography, to provide a valid comparison. The separation patterns of arginyl-tRNA and lysyl-tRNA on MAK column chromatography, of threonyl-tRNA, seryl-tRNA and arginyl-tRNA on Reverse phase type II chromatography and of arginyl, lysyl, seryl and alanyl oligonucleotides on DEAE cellulose chromatography, are shown. In all cases, the distribution patterns of the [3H] and [14C] labels are superimposable and indicate neither the presence of any new or modified species of tRNA nor any alterations in the balance of the host tRNA populations. Evidence is then presented, that from as early as 2 hours post infection there exists in the cytoplasm of paeudorabies infected cells, pulsed for 30 minutes with [3H] uridine-5-T, a species of RNA not detected in similarly labelled non-infected cultures. The RNA, termed 4 1/2s RNA, occupies a larger molecular volume on Sephadex G-l00 than cellular RNA and does not appear to contain methyl groups, derived from [14C]methylmethionine. At least in part, it may be converted to material with characteristic 4s RNA properties by incubation of the cells in the absence of label for a further 60 minutes, or by incubation to vitro with a crude extract of non-infected but not infected cells.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available