Using the jellyfish clytia hemisphaerica to explore the first steps of meiosis by live-imaging.
Oocyte production is a key feature of animal development, comprising a series of carefully regulated events. This project will exploit a new experimental model, the hydrozoan Clytia hemisphaerica, to analyse by live imaging approaches the entire process of oogenesis in isolated female gonads from stem cell to oocyte for the first time. Analyses will focus on early events largely inaccessible in existing animal models, covering the transition from mitotic proliferation of germ cell precursors to meiotic entry. Key events include homologous chromosome pairing, synaptonemal complex formation, and meiotic double strand break formation. Clytia gonads are optically clear, simply organised and maintain oocyte production for several days ex-vivo. The three specific project objectives are 1) to define the spatiotemporal progression of early oogenesis through molecular cartography of the different precursor pools and cell morphology characterisation;  2) to establish conditions for long term imaging, including development of fluorescent markers;  3) to address the function of the key enzyme Spo11 by combining live imaging with CRISPR-mediated gene knockout, monitoring the movements of homologous chromosomes during pairing and identifying the sites of synaptonemal complex polymerisation. This multifaceted project represents a thematic shift for the applicant and involves a new collaboration between expert labs with complementary strengths in developmental, molecular, and cellular biology.  Two-way transfer of knowledge will enable the candidate to develop new skills (microscopy, live imaging, transgenics) whilst introducing her existing expertise with cnidarian biology and bioinformatics to the host labs. The project will improve understanding of the cellular and molecular dynamics of meiosis, establish a new experimental model for oogenesis studies, and provide the candidate with a solid foundation of complementary experience to fulfill her long term career objectives.