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  • The EMBO Journal (1999) 18, 2610 - 2620
  • doi:10.1093/emboj/18.9.2610

Joint action of two RNA degradation pathways controls the timing of maternal transcript elimination at the midblastula transition in Drosophila melanogaster

Arash Bashirullah1,2, Susan R. Halsell2,3, Ramona L. Cooperstock1,4, Malgorzata Kloc5, Angelo Karaiskakis1, William W. Fisher1,2,6, Weili Fu1,7, Jill K. Hamilton1, Laurence D. Etkin5 and Howard D. Lipshitz1,2,4

  1. Program in Developmental Biology, Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8 Canada
  2. Division of Biology, California Institute of Technology, Pasadena, CA, USA
  3. Present address: Department of Cell Biology, Duke University Medical Center, Box 3709, Durham, NC 27710, USA
  4. Department of Molecular and Medical Genetics, University of Toronto, Toronto, Canada
  5. Department of Molecular Genetics, University of Texas M.D.Anderson Cancer Center, Houston, TX, USA
  6. Present address: Exelixis Pharmaceuticals, Inc., 260 Littlefield Avenue, South San Francisco, CA 94401, USA
  7. Present address: Department of Neuroscience, University of Pennsylvania Medical School, Philadelphia, PA 19104, USA

Correspondence to:

Howard D. Lipshitz, E-mail: lipshitz@sickkids.on.ca

Received 22 December 1998; Accepted 5 March 1999; Revised 5 March 1999

Maternally synthesized RNAs program early embryonic development in many animals. These RNAs are degraded rapidly by the midblastula transition (MBT), allowing genetic control of development to pass to zygotically synthesized transcripts. Here we show that in the early embryo of Drosophila melanogaster, 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 targeted to specific classes of mRNAs through cis-acting elements in the 3'-untranslated region and is conserved in Xenopus laevis. The second pathway is activated 2 h after fertilization and functions together with the maternal pathway to ensure that transcripts are degraded by the MBT.

  • Keywords:

    • Drosophila,
    • midblastula transition (MBT),
    • localization,
    • stability,
    • Xenopus