This sandwich placement will be based in the lab of Nic Tapon.

Project summary

How do cells know when to stop growing and dividing once the correct body size has been reached? This fundamental question underpins both the evolution of animal size and growth pathologies like cancer. However, directly observing the tight control of cellular growth and proliferation during development in living animals has been a major challenge.

Our group exploits the Drosophila melanogaster (fruit fly) abdominal epidermis to study developmental growth. The adult epidermis develops from a small niche of progenitor cells called histoblasts. These rapidly divide, replacing surrounding larval cells until they cover the entire abdominal surface, at which point they stop dividing and differentiate. Since this growth occurs during the immobile pupal stage, it is an ideal system to directly observe and rigorously quantify developmental growth patterns in a living organism.

The abdominal epidermis is subdivided into eight segments, each containing a pair of histoblast niches. Our recent work shows that histoblasts can sense space as they do not invade over segment boundaries. We also observed that histoblasts can sense time, as stages of their development tightly correlate with pupal developmental time, which is partly dependent on systemic hormonal cues. In this project, the student will further investigate how histoblasts sense space and time. They will help identify how local cues (such as mechanical forces, tissue architecture and signalling pathways) are integrated with systemic cues (such as nutrients and hormones) to determine final tissue and animal size. The student will be trained in a broad variety of cutting-edge techniques including fly genetics (including CRISPR, RNAi and gene overexpression), optogenetics, laser ablation, live-imaging using confocal microscopy and machine-learning-based image processing and analysis.

Candidate background