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dc.contributor.authorYork-Andersen, Anna Henrietta
dc.date.accessioned2019-02-07T11:43:04Z
dc.date.available2019-02-07T11:43:04Z
dc.date.issued2019-03-23
dc.date.submitted2018-08-21
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/288873
dc.description.abstractEgg activation is a series of highly coordinated processes that prepare the mature oocyte for embryogenesis. Typically associated with fertilisation, egg activation results in the resumption of the cell cycle, expression of maternal mRNAs and cross-linking of the vitelline membrane. While some aspects of egg activation, such as initiation factors in mammals and environmental cues in sea animals, have been well-documented, the mechanics of egg activation in many animals are still not well understood. This is especially true for animals where fertilisation and egg activation are unlinked. In order to elucidate how egg activation is regulated independently of fertilisation, I use Drosophila melanogaster as a model system. This insect provides extensive genetic tools, ease of manipulation for experimentation and is amenable for imaging. Through visualisation of calcium, Processing bodies and meiotic spindles, I show that osmotic pressure acts as an initiation cue for the calcium wave and downstream processes, including the resumption of cell cycle and the dispersion of the translational repression sites. I further show that aquaporin channels, together with external sodium ions, play a role in coordinating swelling of the oocyte in response to the osmotic pressure. I proceed to identify the requirement of internal calcium sources together with a dynamic actin cytoskeleton for a calcium wave to occur. Through co-visualisation of calcium and actin, I provide the first evidence that the calcium wave is followed by a wavefront of non-cortical F-actin at egg activation, which requires the calcium wave. Genetic analysis supports a model where changes in osmotic pressure trigger the calcium wave via stretch sensitive calcium channels in the oocyte membrane and the calcium wave is relayed by nearby channels via the actin cytoskeleton. My work concludes that the mechanism of egg activation in Drosophila is more similar to plants, compared to most vertebrates.
dc.language.isoen
dc.rightsAll rights reserved
dc.rightsAll Rights Reserveden
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/en
dc.subjectegg activation
dc.subjectcalcium
dc.subjectdrosophila
dc.subjectmrna
dc.subjectactin
dc.subjectactin wave
dc.subjectcalcium wave
dc.subjectcytoskeleton
dc.subjectoocyte
dc.subjectoogenesis
dc.subjectosmolarity
dc.titleInvestigating the calcium wave and actin dynamics at Drosophila egg activation
dc.typeThesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridge
dc.publisher.departmentDepartment of Zoology
dc.date.updated2019-02-07T00:18:01Z
dc.identifier.doi10.17863/CAM.36137
dc.publisher.collegeSt John's College
dc.type.qualificationtitlePhD in Zoology
cam.supervisorWeil, Timothy
cam.thesis.fundingfalse


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