DS0402 - Décryptage des fonctions biologiques élémentaires et de leur intégration

Patterning and morphogenesis of the insect body via genetic analysis and cell tracking at single-cell resolution – MorphoGenetics

Submission summary

Drosophila melanogaster is the major insect model organism where mechanisms of cell and developmental biology have been addressed using a plethora of tools and resources. However, important developmental mechanisms are not experimentally tractable in Drosophila because they are secondarily lost or modified in this species. For example, most insects generate their trunk by successive addition of new segments at the posterior end; this process shows many similarities to vertebrate somitogenesis, but it is absent in Drosophila. A second example is the larval head, which in Drosophila becomes highly reduced and involuted into the thorax – an atypical situation for insects. New experimental tools and genomic resources – RNA interference (RNAi), transgenesis, CRISPR, live imaging and a complete genome sequence – provide opportunities to study these developmental processes in a more typical insect model, the red flour beetle Tribolium castaneum.

In this project, we join forces to combine four powerful experimental approaches in Tribolium: the ability to manipulate gene function specifically within small groups of cells (e.g. by clonal analysis), CRISPR-mediated gene editing, clonal marking of cells, high resolution live imaging via light-sheet microscopy (SPIM) and unbiased large-scale screening via RNAi. In the last few years our labs have worked to establish these techniques in Tribolium, and we are now in the position to exploit these to study patterning and morphogenetic mechanisms that underpin head development and trunk segmentation on a level that is unprecedented for emerging model organisms.

We will image these morphogenetic processes at single-cell resolution and follow marked groups of cells to generate precise fate maps of the head and trunk segment precursors and to identify cell behaviours (cell proliferation and cell rearrangements) that contribute to morphogenesis of the head and trunk. To probe the gene regulatory interactions that underpin the development of these structures, we will manipulate the function of candidate genes and signalling pathways within specific populations of cells, by generating genetic mosaics and through localized RNAi. Clonal analysis will allow us to discriminate the cell-autonomous and non-cell-autonomous roles of key developmental regulators, to uncover their effects on cell fate specification and cell behaviour. We will exploit the large-scale RNAi screen currently performed in Tribolium (iBeetle) to identify previously unknown genes with essential roles in these morphogenetic events, and we will analyse their functions in detail by live imaging and clonal gain-of-function and loss-of function approaches.

Our results will uncover mechanisms of head and trunk morphogenesis in a typical insect embryo, based on an understanding of underlying gene function and cell behaviour at single-cell resolution. Addressing similar questions in the head and trunk of Tribolium will allow us to explore new developmental mechanisms and to pioneer new experimental strategies to probe these mechanisms in an emerging insect model. The tools generated here will significantly broaden the scope of mechanistic research possible in Tribolium, which will impact developmental research far beyond the scope of this project.

Project coordination

Michalis AVEROF (Institut de Génomique Fonctionnelle de Lyon)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

IGFL - CNRS Institut de Génomique Fonctionnelle de Lyon
GAUG Georg-August-University Göttingen

Help of the ANR 255,216 euros
Beginning and duration of the scientific project: November 2015 - 48 Months

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