Bicaudal-D (Bic-D) is essential in Drosophila for the establishment of oocyte fate and polarity within the developing oocyte. To study these processes we have engineered a chimeric Bic-D::GFP fusion protein which behaves like the endogenous Bic-D polypeptide. We have identified three genes which are required for the normal subcellular distribution of Bic-D::GFP two genes predicted to encode RNA binding proteins (egalitarian and orb) and Dynein heavy chain. In particular, they affect Bic-D::GFP localization during the early germarial stages of oogenesis during which oocyte fate is established, or later when anterior-posterior polarity is initiated. Our results support the model that Bic-D acts in conjunction with mRNA binding proteins and a negative-end directed microtubule motor in localizing mRNAs. Throughout stages 1--6 of oocyte development, Bic-D::GFP accumulates in the oocyte in a strong posterior cortical focus, resembling a spool, that is aligned with a crater-like indentation in the oocyte nucleus. The aligned focus and crater reveal an early oocyte polarity and a previously undescribed asymmetric subcellular structure that may be involved in tethering the oocyte nucleus. Shape, positioning and orientation of the oocyte nucleus change around stage 6--7, concomitantly with a change in position of the Bic-D::GFP focus to the presumptive dorsoanterior corner. This re-orientation appears to anticipate the establishment of a new dorsoventral polarity in the oocyte and egg chamber. Dhc and Bic-D are both involved in the process of re-orientation of the oocyte nucleus and in polarity formation.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.21619 |
| Date | January 1999 |
| Creators | Paré, Chantal. |
| Contributors | Suter, Beat (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001659836, proquestno: MQ50851, Theses scanned by UMI/ProQuest. |
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