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

• Applicant: Professor Dr. Gregor Bucher
• Subject Area: Evolutionary Cell and Developmental Biology (Zoology)
• Term: from 2015 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 283945540

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 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 similar to vertebrate somitogenesis, but it is absent in Drosophila. Further, the larval head becomes highly reduced and involuted into the thorax in Drosophila, which is an atypical situation for insects. New experimental tools and genomic resources (RNA interference (RNAi), transgenesis, CRISPR, live imaging) now allow 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 manipulation of gene function 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 years our labs have worked to establish these techniques in Tribolium, and we now want to exploit them to study head development and trunk segmentation on a level unprecedented in emerging model organisms. We will image these morphogenetic processes at single-cell resolution and follow marked groups of cells to generate precise fate maps and to identify cell behaviours contributing to morphogenesis of the head and trunk. To probe the gene regulatory interactions, we will manipulate the function of candidate genes and signalling pathways within restricted 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 developmental genes and to uncover their function. We will exploit the large-scale RNAi screen currently performed in Tribolium (iBeetle) to identify previously unknown genes with essential roles in these processes, and we will analyse their functions in detail. 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.

• DFG Programme: Research Grants
• International Connection: France
• Partner Organisation: Agence Nationale de la Recherche / The French National Research Agency
• Cooperation Partner: Professor Dr. Michalis Averof