Drummond, Douglas R. (1985) The stability, movement and expression of natural and synthetic mRNAs injected into 'Xenopus' oocytes. PhD thesis, University of Warwick.

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Abstract

The stability and movement of several natural and synthetic mRNAs in Xenonus oocytes was examined. Although the movement of injected mRNAs has important implications for experiments in oocytes, this aspect of mRNA behaviour has never been examined before.

At least 50% of the injected natural poly(A)+ mRNAs (9S rabbit globin, chicken ovalbumin and lysozyme mRNAs) remained stable over a 48h period, irrespective of the amount injected. 50% of the natural poly(A) reovirus mRNA was degraded within 24h of injection, irrespective of the amount injected, and no further degradation occurred over the next 24h.

Synthetic mRNAs coding for chicken lysozyme, calf preprochymosin and Xenonus β globin protein were transcribed in vitro using Sp6 RNA polymerase. Capping and polyadenylation increased the stability of the synthetic mRNAs with at least 42% of capped, poly(A) transcripts remaining 48h after injection into oocytes.

Capping and polyadenylation also increased the translational efficiency of most of the synthetic mRNAs. The exception was one Xenopus β globin transcript with an unusual 3' end of 20 As and 30 Cs, where further polyadenylation decreased translational efficiency.

The movement of all the natural poly(A)+ mRNAs injected into oocytes was very slow. Little movement of RNA from the animal to the vegetal half was observed, even 48h after injection. In contrast, similar amounts of mRNA were present in both halves 48h after vegetal pole injection. Similar results were obtained with poly(A) reovirus mRNAs.

The capped poly(A) synthetic mRNAs moved more rapidly in oocytes than either capped poly(A) synthetic mRNAs or naturally occurring mRNAs. However equilibration of the injected RNA still did not occur even 24h after injection.

The movement of the proteins encoded by the natural poly(A)+ mRNA was examined in the 6h period after injection, when little mRNA movement had occurred. The sequestered secretory proteins ovalbumin and lysozyme moved much more slowly than the cytosolic protein globin in the same oocytes.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QL Zoology Q Science > QP Physiology
Library of Congress Subject Headings (LCSH):	Messenger RNA -- Research, Xenopus -- Research, Ovum
Official Date:	October 1985
Dates:	Date Event October 1985 Submitted
Institution:	University of Warwick
Theses Department:	Department of Biological Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Colman, Alan
Extent:	xi, 157 leaves : illustrations
Language:	eng

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