Thèse: Anna GILLES
de 13:00 à 17:00
|Amphi E (Site Monod, ENS)
Members of the Jury
Mme Evelyn HOULISTON
Mme Muriel GRAMMONT
Mme Bénédicte DURAND
M Michael AKAM
M Michalis AVEROF
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An important objective of developmental biology is to understand the cellular basis of morphogenesis, including fates of distinct progenitor cells in the developing embryo. Describing morphogenesis in representative species of different groups or phyla provides a solid basis for comparing similar processes in different organisms, and for drawing conclusions about the evolution of animal body plans. To this end, scientists develop techniques in selected species - these include manipulation of gene function, marking and tracking of distinct populations of cells, and in vivo imaging.
In this thesis, I present my efforts to enhance the genomic toolkit of the beetle Tribolium castaneum. I use a recently discovered genome editing technique, CRISPR/Cas, to introduce precise alterations in the
Tribolium genome, including the introduction of large fragments by homologous recombination. I show that all CRISPR/Cas components are driven efficiently by endogenous Tribolium promoters. Based on these results, I develop VALCYRIE, a transgenic approach to mark single cell clones in developing Tribolium embryos.
This work allows me to investigate the fates of the cells in the posterior terminal region of the Tribolium blastoderm. Using a clonal labeling approach, I demonstrate that these cells give rise to primordial germ cells and posterior mesoderm. With the same technique, I demonstrate that the hindgut of Tribolium develops from a distinct cell population in the early germ band. Using high-resolution time lapse microscopy, I describe the fates of single cells in the Tribolium
blastoderm and shed new light on the fate map of gnathal and thoracic segments of the embryo at this stage. Furthermore, I show that the amnion of Tribolium expands greatly during early development. Based
on imaging data, I review the fate map of the early germ band with regard to the amnion and the embryonic ectoderm.