Translational Regulation in the Early Drosophila Embryo PDF Download

Author: Meryl Nelson
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Jason Dumelie
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Ramona L. (Ramona Leigh) Cooperstock
Publisher: National Library of Canada = Bibliothèque nationale du Canada
ISBN: 9780612918771
Category :
Languages : en
Pages : 414

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Author: Mandy Jeske
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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During early embryogenesis of Drosophila, transcription does not contribute to the regulation of gene expression, and translational control becomes eminently important. The nanos mRNA specifies the development of posterior structures in the Drosophila embryo. Translation of nanos mRNA is restricted to the posterior pole of the embryo, and the vast majority of nanos mRNA within the embryonic cytoplasm is silenced. Translational repression of nanos is mediated by the protein Smaug, which can bind specific sequences, Smaug recognition elements (SREs), in the nanos 3' UTR. At the posterior pole, translation of nanos mRNA is derepressed by the action of Oskar protein. In this doctoral study, a cell-free system derived from Drosophila embryos was established that recapitulates the SRE-dependent translational regulation. Both SRE-dependent deadenylation and translation repression were biochemically investigated. Addition of recombinant Oskar to the extracts prevents SRE-dependent repression.

Author: Benjamin Douglas Pinder
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Yan Song
Publisher:
ISBN: 9780549084921
Category : Messenger RNA.
Languages : en
Pages : 172

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Taken together, I propose that posterior anchoring of nos mRNA in the oocyte is dependent of Hsp90, LKB1 and the 798 gene products. Upon its localization, translation of nos is activated partially through a structural switch of its 3'UTR.

Author: Anupama Dahanukar
Publisher:
ISBN:
Category : Drosophila
Languages : en
Pages : 288

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Author: George M. Malacinski
Publisher: Springer Science & Business Media
ISBN: 1468446282
Category : Science
Languages : en
Pages : 377

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The early embryo has emerged as the focal point for analysis of the regulation of gene expression for several reasons. First, the fact that embryogenesis is under genetic control has been appreciated from the earliest days of classical embryology. When experimental techniques became available it was therefore logical that they should be applied to the embryo. With each new advance in methodology, interest in embryonic gene expression studies has increased. Second, many embryos offer unique opportunities for the investigation of specific aspects of the regulation of gene expression. Several phenomena--eg. , control of translation--can be very conveniently studied in a variety of marine invertebrate embryos. Those embryos contain large stores of maternally inherited mRNA which are translated in a highly ordered fashion during specific stages of post fertilization development. Marine invertebrate eggs can be conveniently artifically inseminated and labeled with radioactive precursors. Their analysis is leading to important insights into the mechanisms which regulate gene expression at post-transcriptional levels. Third, recent advances in both transmission and recombinant DNA genetics, especially in organisms such as Drosophila, are providing special opportunities for the analysis of regulatory mechanisms which operate at the level of the genome. Specific genes have been identified, isolated, and--in some instances--sequenced. The opportunity is now available to study the regulation of the expression of single genes in a vertical fashion--from the primary sequence of the gene to the tissues and organs which are the products of morphogenesis.

Author: Stephen William Eichhorn
Publisher:
ISBN:
Category :
Languages : en
Pages : 286

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Eukaryotic mRNAs have a cap structure at their 5' ends and a poly(A) tail at their 3' ends, and the proteins that bind these features increase the stability and translation of an mRNA. The influence of the poly(A) tail on translation was discovered decades ago, but primarily with regard to the idea that an mRNA with a poly(A) tail is better translated than one without. The influence of differences in tail length on translation had been assessed for just a few mRNAs, and in these cases long-tailed mRNAs were better translated than short-tailed mRNAs. We measured the poly(A)-tail length and translational efficiency of mRNAs corresponding to thousands of different genes in 35 different cell types or contexts. Extending previous singlegene studies, we found a global relationship between tail length and translational efficiency in Drosophila oocytes, and Drosophila, Xenopus, and zebrafish embryos. Surprisingly, in all three species, the strong coupling between tail length and translational efficiency was lost once the embryos reached gastrulation, and there was no coupling in the post-embryonic contexts we examined. We thus demonstrated that poly(A)-tail length is a major determinant of translational efficiency during early animal development and discovered a broadly conserved developmental switch in translational control. During the tail-length regulatory regime of the early embryo, a protein or microRNA might regulate translation by changing the poly(A)-tail length of an mRNA, interacting with the translation machinery, or both mechanisms. We characterized the mechanism used by two translational regulatory proteins in Drosophila, finding that they predominantly act by regulating tail length. Likewise, in early zebrafish embryos, microRNAs repress the translation of their hundreds of mRNA targets by shortening poly(A) tails. Our findings indicate that much of the translational regulation in early development is achieved by regulating poly(A)-tail lengths. Outside of early embryonic contexts, microRNAs regulate gene expression by causing both translational repression and mRNA degradation. We greatly expanded the mammalian cell types and contexts in which the steady-state and pre-steady-state effects of a microRNA had been examined globally for endogenous mRNAs. In all post-embryonic contexts with substantial microRNA-mediated repression, the predominant mode of repression was mRNA degradation.

Author: Wael Tadros
Publisher:
ISBN: 9780494280232
Category :
Languages : en
Pages : 264

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Early embryonic development is controlled by maternally deposited proteins and transcripts. Egg activation triggers a cascade of posttranscriptional mechanisms that are crucial to the regulation of these maternal mRNAs during this time of transcriptional quiescence. These mechanisms include translational activation, repression and transcript destabilization. Here I show that, in Drosophila, the PAN GU (PNG) kinase complex sits near the top of this cascade that ultimately leads to the destabilization of maternal mRNAs. The genes png, plutonium (plu) and giant nuclei (gnu), which encode the components of this complex, were recovered in a screen for maternal effect lethal mutants which fail to undergo degradation. I show that png's control of transcript destabilization is genetically separable and therefore independent of its well characterized role in the cell cycle. PNG acts following egg activation in promoting the translation of SMAUG (SMG), a major posttranscriptional regulator. Our gene-expression profiling experiments show that SMG is responsible for targeting two thirds of degrading maternal mRNAs. PNG activates smg translation in a poly(A)-independent manner acting through the smg 3'UTR. Finally, I show that PNG also has a SMG-independent mechanism of eliciting transcript decay.