Abstract

The goal of the project is to characterize theoretically the observed allometric scaling in Planaria. Although animals vary dramatically in size, shape, habitat, and lifestyle, conserved relationships linking mass, growth and metabolism are found across species. The origin of such “allometric” or “scaling” relationships is a classic question in biology, which remains largely open. Perhaps the most famous example is Kleiber’s law, which reports a ~³⁄₄ power law between metabolic rate and organism mass. Standard theories propose that branching of transport networks recapitulate Kleiber’s law. The biological foundation for such networks could be the cardiovascular or respiratory systems in animals or mitochondrial networks in cells. Further theoretical work showed that optimal transport in resource distribution networks is sufficient to explain Kleiber’s law.

However, recent experimental work on planarians challenged the idea that Kleiber’s law can only emerge from a whole-body transport network and instead proposed that it results from a nonlinear correlation between average cell mass and organism mass, specifically due to lipid storage. This result supports the idea that the allocation of “resources” (building blocks and energy supplies) into different cellular components (RNA, proteins, lipids and other macromolecules) can impact whole-organism properties such as metabolic rate.

To address this question, we will develop hybrid theories encompassing both resource distribution and resource allocation and compare them with the data on planaria. The work will be carried out in collaboration with the experimental group of Jochen Rink (Max Planck, Gottingen)

Learning opportunities Our project offers several learning opportunities in virtue of the integration of data analysis with quantitative modelling and computational tools, in addition to guaranteeing the acquisition of several standard techniques. Among other things, you will learn • Cell growth physiology • Scaling theory • Quantitative data analysis
• Interdisciplinary collaboration

Contacts If you are interested in the project, please email us at sandro.azaele@unipd.it marco.cosentino-lagomarsino@ifom.eu

• This project will be jointly-supervised by Prof. Sandro Azaele (Laboratory of Interdisciplinary Physics, Physics and Astronomy Dept. “G. Galileo”, Univeristy of Padova) and by Prof. Marco Cosentino Lagomarsino (Statistical Physics of Cells and Genomes, IFOM and University of Milan). IFOM is a top-level scientific institute in Milan, performing curiosity-driven fundamental biology research motivated by understanding cancer.