The effect of oestradiol-17beta on the synthesis of the components of polyribosomes in the immature rat uterus

Merryweather, Michael John (1980) The effect of oestradiol-17beta on the synthesis of the components of polyribosomes in the immature rat uterus. PhD thesis, University of Glasgow.

Abstract

An investigation into the effect of oestradiol-17beta on the synthesis of the components of polyribosomes in the immature rat uterus has been carried out. Previous studies have shown that rRNA synthesis is stimulated 2-4hr after treatment with the hormone. This is preceded by, and dependent on, a stimulation of the synthesis of HhRNA, detectable 30 after giving the hormone. It has been postulated that mRNA sequences present in the HnRRA must be translated before the stimulation of rRNA synthesis can occur. A method for the preparation of ribosomes from immature rat uteri, taking precautions to minimise ribonuclease activity, is described. Polysome profiles have been analysed on sucrose density gradients in order to detect alterations in protein synthesis following hormone treatment. Ribosomes from control animals are mainly in the form of monomers and dimers, but following oestrogen treatment, there is an increase in the proportion of polysomes. This effect is first detectable 30 min - 1hr after giving hormone, reaching a maximum after 4 hr and declining after 16 hr. The kinetics of the synthesis of the components of the polysomes in response to oestrogen have been studied. The RNA was extracted from the polysomes and fractionated on oligo (dT) cellulose in order to study the synthesis of mRNA and rRNA, whilst the ribosomes were dissociated into subunits and the subimits separated on sucrose density gradients in order to study the synthesis of ribosomal proteins. It has been shown that the aggregation of ribosomes into polysomes 2-4hr after hormone treatment occurs as a result of the association of newly-synthesised mHNA with pre-existing ribosomes. Despite the stimulation of rRNA synthesis 2-4hr after oestrogen administration, the incorporation of newly-synthesised rRNA into ribosomes is not maximal until 12hr after hormone treatment. The incorporation of newly-synthesised ribosomal proteins into ribosomes is also maximal at this time. Fractionation of these newly-synthesised proteins by polyacrylamide gel electrophoresis has been carried out in order to confirm their identity as ribosoinal proteins. The kinetics of the incorporation of newly-synthesised ribosomal proteins into ribosomes follow the kinetics of the stimulation of total protein synthesis in the uterus by oestrogen. The peak of maximal incorporation of newly-synthesised mRNA into polysomes coincides with the peak of maximal protein synthesis. These results are discussed in relation to the postulated mechanism of oestrogen-stimulated rRNA synthesis in the immature rat uterus. The involvement of protein synthesis in rRNA synthesis is also discussed.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Endocrinology.
• Colleges/Schools: College of Medical Veterinary and Life Sciences
• Supervisor's Name: Knowler, Dr. J.T.
• Date of Award: 1980
• Depositing User: Enlighten Team
• Unique ID: glathesis:1980-72049
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 17 May 2019 13:14
• Last Modified: 26 Oct 2021 14:36
• Thesis DOI: 10.5525/gla.thesis.72049
• URI: https://theses.gla.ac.uk/id/eprint/72049