Morphogenesis one century afterOn Growth and Form

Abstract

Morphogenesis, the study of how forms arise in biology, has attracted scientists for aeons. A century ago, D'Arcy Wentworth Thompson crystallized this question in his opus On Growth and Form (Thompson, 1917) using a series of biological examples and geometric and physical analogies to ask how biological forms arise during development and across evolution. In light of the advances in molecular and cellular biology since then, a succinct modern view of the question states: how do genes encode geometry?Understanding this fascinating problem requires insight into how shape emerges when molecular information and physical forces are regulated over many different scales in space and time. To address this requires an appreciation of the enormous 'morphospace' of potential shapes and sizes that living forms can take up. In parallel, we need to consider the large diversity in the genetic space of potential regulatory interactions that influence form. While the conceptual framework of developmental patterning explains how cells acquire information and how this defines their behaviours, Thompson's agenda of describing biological processes in mathematical terms is based on understanding how instabilities and patterns in physical systems might be harnessed by evolution. Consequently, the subjects of morphological ( phenotypic) and regulatory (genotypic) diversity that are separated by many orders in length scales, have not been sufficiently coupled intellectually.

Multi-view light-sheet imaging and tracking with the MaMuT software reveals the cell lineage of a direct developing arthropod limb

“…Morphogenesis, or the origin of biological form, is one of the oldest and most enduring problems in biology. Embryonic tissues change their size and shape during development through patterned cell activities controlled by intricate physico-chemical mechanisms ( Day and Lawrence, 2000 ; Heisenberg and Bellaïche, 2013 ; Keller, 2013 , 2012 ; Lecuit and Mahadevan, 2017 ; LeGoff and Lecuit, 2015 ). Developmental processes have been explained traditionally in terms of genes and gene regulatory networks, and a major challenge is to understand how the genetic and molecular information is ultimately translated into cellular activities like proliferation, death, change of shape and movement.…”

Cytocortex-dependent dynamics of Drosophila Crumbs controls junctional stability and tension during germ band retraction

“…The involvement of Crb in the regulation of apical cell surface size and AJ stability, on the one hand, and the requirement of cell surface area changes and cellular remodelling during GBR, on the other (Lecuit and Mahadevan, 2017;Martin and Goldstein, 2014;Rauzi et al, 2010) raises the question of whether both processes are connected. We hypothesise that modulation of apical surface area and AJ remodelling relies on continuous turnover and dynamic modulation of Crb localisation and stability at the plasma membrane.…”

Topological defects in the nematic order of actin fibres as organization centres of Hydra morphogenesis

“…These observations suggest that the nematic orientation field can be considered a "mechanical morphogen" whose dynamics, in conjugation with various biochemical and mechanical signaling processes, result in the robust emergence of functional patterns during morphogenesis.Animal morphogenesis involves multiple mechanical and biochemical processes, spanning several orders of magnitude in space and time, from local dynamics at the molecular level to global, organism-scale morphology. How these numerous processes are coordinated and integrated across scales to form robust, functional outcomes remains an outstanding question [1][2][3][4] .Developing an effective, coarse-grained description of morphogenesis can provide essential insights towards addressing this important challenge. Here, we focus on whole-body regeneration in Hydra, a small fresh-water predatory animal, and provide an effective description of the morphogenesis process that is based on the dynamic organization of the supra-cellular actin fibers in regenerating tissues 5,6 .…”