Séminaire externe - Lendert Gelens, KU Leuven (Belgique) - Salle De Conférence - RDC Bâtiment 4 - IGDR - Campus Santé Villejean - Université De Rennes

Beyond Arrhenius: Mechanistic origins of temperature scaling in embryonic development

Temperature profoundly influences organismal physiology and ecological dynamics, with ectothermic species being particularly sensitive to environmental temperature fluctuations. While the Arrhenius equation, originally used for single enzyme-catalyzed reactions, has been widely used to describe the temperature dependence of complex physiological processes, it often fails to capture deviations at temperature extremes. Here, we investigate the mechanistic origins of temperature scaling during embryonic development, spanning from the early cell cycle oscillator to later developmental events.
Using experimental data from Xenopus laevis and tropicalis, Danio rerio, and published datasets from Caenorhabditis elegans and briggsae, and Drosophila melanogaster, we find that the apparent activation energies for the early embryonic cell cycle are remarkably similar across diverse ectotherms. Computational modeling reveals that both biphasic temperature scaling in critical components of the cell cycle oscillator and imbalances in activation energies of partially rate-determining enzymes contribute to the observed temperature dependence. Experimental studies in cycling Xenopus extracts confirm the presence of these mechanisms, while in vitro analysis of individual cell cycle regulators highlights significant differences in activation energies.
Extending beyond early embryogenesis, we apply a Markov framework to model cascades of reversible processes in later developmental stages. This general model identifies three distinct temperature-scaling regimes: Arrhenius-like behavior at temperature extremes and quadratic exponential scaling at intermediate temperatures. By integrating this approach with experimental data across multiple ectothermic species, we demonstrate that non-Arrhenius scaling arises as an intrinsic network property rather than solely from individual enzyme kinetics.
Together, these findings provide a unified mechanistic perspective on the temperature dependence of biological processes throughout embryonic development and offer critical insights into how ectothermic organisms may respond to environmental temperature changes in the context of global climate shifts.

Le laboratoire de Lendert Gelens cherche à acquérir une compréhension fondamentale des processus dynamiques qui coordonnent les systèmes vivants en utilisant une approche interdisciplinaire combinant la biologie expérimentale, la modélisation basée sur les données et la physique informatique.
Plus précisément, ils travaillent in vitro à la création de cellules artificielles présentant un comportement proche de la vie, in vivo à l'étude du développement embryonnaire précoce, in silico à l'analyse de modèles mathématiques et au développement technologique de nouveaux outils.

Contact : Romain Gibeaux

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