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Temporal and spacial control of RNA stability in the early embryo of Drosophila melanogaster


Bashirullah, Arash (1999) Temporal and spacial control of RNA stability in the early embryo of Drosophila melanogaster. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/HWD3-HB90.


Early embryogenesis in metazoa is controlled by maternally synthesized products. Among these products, the mature egg is loaded with transcripts representing approximately two thirds of the genome. A subset of this maternal RNA pool is degraded prior to the transition to zygotic control of development. This transfer of control of development from maternal to zygotic products is referred to as the midblastula transition (or MBT). It is believed that the degradation of maternal transcripts is required to terminate maternal control of development and to allow zygotic control of development to begin. Until now this process of maternal transcript degradation and the subsequent timing of the MBT has been poorly understood. I have demonstrated that in the early embryo there are two independent RNA degradation pathways, either of which is sufficient for transcript elimination. However, only the concerted action of both pathways leads to elimination of transcripts with the correct timing, at the MBT. The first pathway is maternally encoded, is triggered by egg activation, and is targeted to specific classes of mRNAs through cis-acting elements in the 3' untranslated region (UTR}. The second pathway is activated 2 hr after fertilization and functions together with the maternal pathway to ensure that transcripts are degraded by the MBT. In addition, some transcripts fail to degrade at select subcellular locations adding an element of spatial control to RNA degradation. The spatial control of RNA degradation is achieved by protecting, or masking, transcripts from the degradation machinery. The RNA degradation and protection events are regulated by distinct cis-elements in the 3' untranslated region (UTR). These results provide the first systematic dissection of this highly conserved process in development and demonstrate that RNA degradation is a novel mechanism used for both temporal and spatial control of development.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Temporal and spacial control ; RNA stability ; embryo ; Drosophila melanogaster
Degree Grantor:California Institute of Technology
Major Option:Biology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Lipshitz, Howard D.
Thesis Committee:
  • Lipshitz, Howard D. (chair)
  • Meyerowitz, Elliot M.
  • Sternberg, Paul W.
  • Wold, Barbara J.
  • Zinn, Kai George
Defense Date:10 May 1999
Non-Caltech Author Email:bashirullah (AT)
Record Number:CaltechTHESIS:03052014-104605861
Persistent URL:
Related URLs:
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Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8104
Deposited By: Benjamin Perez
Deposited On:05 Mar 2014 19:04
Last Modified:09 Nov 2022 19:19

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