Abstract

Ana Patricia Ramos

Title:Forming an Eye: from cell behaviour to tissue shape changes

Abstract: Building an organ is a multistep process in which correct morphogenesis arises from feedback loops between genetic regulation and mechanical forces. A key morphogenetic event is the emergence of tissue curvature, which is essential for various developmental processes, such as gastrulation, and shapes multiple organs, including the heart and neural tube.

Curvature can develop alongside other cellular and tissue rearrangements. In many of these complex contexts, the biomechanical interactions driving curvature remain unclear, as the contributions of individual rearrangements and their interplay are difficult to disentangle.

To address this, we investigated the morphogenesis of the vertebrate optic cup, a highly curved structure that forms from a flat bilayered optic vesicle. Using zebrafish as a model system, where cell and tissue dynamics can be studied in native 4D conditions, we combined in vivo experiments, 4D segmentation and analysis, and theoretical modeling. This interdisciplinary approach allowed us to identify key players driving the emergence of optic cup curvature.

Kumud Saini (Robinson Lab, Sainsbury Laboratory)

Tittle: Temperature Regulation of Cell Cycle and Growth Dynamics in Arabidopsis

Abstract: Living organisms exhibit maximum growth when they are in optimal conditions. A plastic developmental program allows organisms to sense environmental cues and express phenotypes better fitting their environments. An increase in global temperature has been shown to affect plant phenology, including the timing of vegetative and reproductive growth. In Arabidopsis thaliana, warm growth temperatures promote cell elongation in the hypocotyl, stems, and petioles, which is predicted to aid in cooling and protecting meristems. In contrast, warm temperature restricts leaf growth by inhibiting cell division and promoting cell expansion. To explain this contrasting effect on division and expansion and to explore the causal link between the two, we combined live cell imaging with Atomic Force Microscopy (AFM) in young proliferating leaves. Through cell-lineage tracking and imaging of cell cycle markers, we propose that elevated temperatures affect cell division frequency and alter the timing of cell cycle phases. AFM measurements showed that the mechanical properties of cell walls of diving and expanding cells differ, where softening of the wall potentially aids in growth acceleration. Together, we show how fluctuations in environmental temperature shape cell cycle and growth dynamics in Arabidopsis thaliana.