Speakers: Tatyana Gavrilchenko (Flatiron Institute, NY, USA)
The insect respiratory system is a network of air-filled tubes permeating the animal body, supplying oxygen for metabolic activity and removing waste carbon dioxide. The majority of gas exchange occurs in the finest regions of the tracheal system, the terminal cells. These cells have a unique and highly specialized tree-like structure with long thin branches, reminiscent of neuronal arbors. While many aspects of the terminal cell are understood on a molecular level, including the mechanisms that guide branch extension and lumen formation, the macroscopic network features that allow for proper oxygen distribution remain mysterious. We use the Drosophila terminal cell as a model system for fundamental developmental problems of network structure and functions, utilizing an imaging data set that fully maps the structure of over one hundred individual cells. First, we find that scaling relations succinctly encapsulate the dynamics of growing networks, and use the empirical scalings observed in the terminal cells to construct a minimal model of network growth that describes the system. Second, to understand the interplay between structure and function in the trees, we developed a model of oxygen distribution by a network embedded in a two-dimensional absorbing tissue, driven purely by diffusion along oxygen partial pressure gradients. Our method works well on complex geometries, including curved and branched networks that approximate the geometry of the terminal cells. These investigations offer insights into mammalian capillary networks, which have different structural features and delivery mechanisms from terminal cells but are guided by similar developmental principles. Understanding the salient features that govern the structure of these biological networks is essential to designing synthetic vasculature, a major step in the manufacture of artificial organs.
https://indico.ijs.si/event/2138/