Robustness and Individuality in Organ Growth Control of C. elegans
Correctly sized body parts are crucial for organismal function. For example, small discrepancies in limb length severely obstruct motility, and overgrowth of cardiac muscle is a prevalent cause of heart failure. The growth of different cells and organs must therefore be tightly coordinated to prevent that even small differences in growth rates amplify to large differences in size during development. How growth signals are propagated from cell to cell, and how organs integrate combinatorial signals from different tissues is a fundamental, yet poorly addressed question of high biomedical relevance. We address this question using quantitative live imaging experiments with the nematode worm C. elegans.
Specifically, we used strains expressing a green fluorescent protein in the pharynx of C. elegans and a red fluorescent protein in all cells of the body. Using a micro cultivation technique, we grew individual animals in small chambers that can be maintained on a fluorescent microscope over many days and the entire development of C. elegans. This technique allows us to precisely monitor the growth of the pharynx and the body size at high time resolution for individual animals and measure the heterogeneity in growth and size among individuals of an isogenic population. Our key finding is that there exists a molecular mechanism that coordinates the growth of the pharynx and the body, such that the relative proportions between the pharynx and the body length are very robust to even strong perturbations.
The “Nikon piezo stage” that we were able to acquire thanks to the UniBern Forschungsstiftungs’ grant, has become essential for our investigations. The piezo drive enables extremely rapid acquisition of three dimensional image stacks with minimal time delay between optical sections. This speed is crucial for our application, as the animals are not anesthetized inside the chambers and move rapidly. Thanks to the rapid acquisition, we can now effectively acquire large stacks of images and reconstruct 3-dimensional representations of the animals.
Prof. Dr. Benjamin Towbin
Institute of Cell Biology
