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Interspersed Poly(A) RNAs of Amphibian Oocytes are not Translatable

Richter, Joel D. and Smith, L. Dennis and Anderson, David M. and Davidson, Eric H. (1984) Interspersed Poly(A) RNAs of Amphibian Oocytes are not Translatable. Journal of Molecular Biology, 173 (2). pp. 227-241. ISSN 0022-2836. doi:10.1016/0022-2836(84)90191-8.

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The poly(A) RNA of the Xenopus oocytes has been shown to include both single copy and interspersed transcripts. Interspersed maternal poly(A) RNAs contain repetitive sequence elements distributed within regions transcribed from single copy sequences. When renatured these RNAs form partially double-stranded RNA networks, and as shown earlier this can be utilized for preparative separation of interspersed maternal transcripts from maternal transcripts that remain single-stranded after renaturation (Anderson et al., 1982). The translational activity of these RNA fractions was tested in vitro, in wheat germ and reticulocyte systems. While the single-stranded fractions supported protein synthesis, the interspersed oocyte RNAs displayed little translational activity. Translational activity was measured in vivo by injection into the Xenopus oocyte. Oocytes previously injected with globin mRNA were injected with increasing amounts of single-stranded, double-stranded, or denatured double-stranded RNA fractions, and the amount of globin synthesis was determined. It was found that single-stranded RNA competes with globin mRNA for the limited translational apparatus of the oocyte, as manifested by a quantitative reduction of globin synthesis. However, globin synthesis was not affected when double-stranded RNA, either in renatured or denatured form, was injected. We conclude that the interspersed RNAs are not translated within the oocyte. The amount of single and double-stranded RNAs loaded onto polysomes in the injected oocytes was also determined. Sixty seven per cent of radio-iodinated single-stranded RNA pelleted with polysomes in injected oocytes, whereas less than 20% of similarly labeled double-stranded RNA pelleted with polysomes. This value is similar to that obtained when partially hydrolyzed RNA is injected, suggesting again that essentially none of the interspersed RNA is translated in vivo. The significance of these findings in relation to translational regulation during oogenesis and early development is discussed.

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Additional Information:© 1984 Academic Press Inc. (London) Ltd. Received 23 April 1983. Edited by W. Franke. This work was supported by grants from the National Institutes of Health to L.D.8. (HD04229), E.H.D. (HD05753) and J.D.R. (GM32559).
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Official Citation:Joel D. Richter, L.Dennis Smith, David M. Anderson, Eric H. Davidson, Interspersed poly(A) RNAs of amphibian oocytes are not translatable, Journal of Molecular Biology, Volume 173, Issue 2, 1984, Pages 227-241, ISSN 0022-2836, (
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ID Code:66182
Deposited By: Ruth Sustaita
Deposited On:14 Apr 2016 23:08
Last Modified:10 Nov 2021 23:54

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