The translation of a series of <I>cat </I>mRNAs containing either the <I>HSP26 </I>5'- leader or various artificial 5'-leaders (Vega Laso <I>et al., </I>1993) were analysed during growth. From this study, the relative translational efficiencies of these mRNAs were shown to vary from 2% to 100% during mid-exponential phase as observed previously (Vega Laso <I>et al.,</I>1993). However, upon analysing the translation of the various <I>cat </I>constructs during growth, their relative translational efficiencies did not change significantly as yeast cells approached stationary phase. A new set of <I>lacZ </I>mRNAs carrying different natural 5'-leaders (<I>PGK1, PYK1, RpL3, Rp29, GDH1, HSP26, HSP12 </I>and <I>TH14</I>) were constructed. These <I>lacZ </I>mRNAs were placed under the control of the promoters taken from genes expressed during different phases of growth (<I>PGK1 </I>and <I>HSP26</I>). Even though the various <I>PGK1-lacZ </I>and <I>HSP26-lacZ </I>mRNAs were translated differentially, the ability of these mRNAs to compete for the translational apparatus did not appear to change as cells entered stationary phase. The translation of a variety of natural mRNAs encoding a wide range of functions was then analysed by determining their polysomal distribution at various points during growth. Irrespective of the growth phase, a large proportion of each mRNA was detected in the polysomal fractions, suggesting that they continued to be translated in stationary phase. Overall, the data strongly suggest that, under the conditions tested, an excess translational capacity exists in stationary phase yeast cells. Hence gene expression may be largely regulated by transcription upon entry to stationary phase.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:320770 |
| Date | January 1996 |
| Creators | Dickson, Lorna Mary |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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