A coupled mechano-biochemical model for cell polarity guided anisotropic root growth

Plants develop new organs to adjust their bodies to dynamic changes in the environment. How independent organs achieve anisotropic shapes and polarities is poorly understood. To address this question, we constructed a mechano-biochemical model for Arabidopsis root meristem growth that integrates biologically plausible principles. Computer model simulations demonstrate how differential growth of neighboring tissues results in the initial symmetry-breaking leading to anisotropic root growth. Furthermore, the root growth feeds back on a polar transport network of the growth regulator auxin. Model, predictions are in close agreement with in vivo patterns of anisotropic growth, auxin distribution, and cell polarity, as well as several root phenotypes caused by chemical, mechanical, or genetic perturbations. Our study demonstrates that the combination of tissue mechanics and polar auxin transport organizes anisotropic root growth and cell polarities during organ outgrowth. Therefore, a mobile auxin signal transported through immobile cells drives polarity and growth mechanics to coordinate complex organ development.

Design principles of plant root morphogenesis

Understanding how an independent organ develops from the stem cell populations in the process called morphogenesis is a pressing challenge in developmental biology and medicine. Plants build up new organs such as roots to adjust their bodies to dynamic changes in the environment, thereby providing a tractable model to address this challenge. Here, we combined empirical data with advanced computer modeling techniques to build a mechanistic cell-based framework for the morphogenesis of the plant root. Our framework relies on experimentally supported design principles underlying the multi-layered feedback between tissue mechanics, cell growth, and directional cell-to-cell transport of growth regulator auxin. Model simulations reconstruct experimentally-observed patterns of anisotropic growth, auxin distribution, and cell polarity, as well as several root phenotypes caused by chemical, mechanical, or genetic perturbations. Furthermore, our model provides new insights into mechanisms of sustained root growth and cell polarity establishment. This work reveals that mobile auxin signal feeds back on cell polarity and growth mechanics to instruct the morphogenesis of an independent organ.

Seven Challenges in the Multiscale Modelling of Multicellular Tissues

The growth and dynamics of multicellular tissues involve tightly regulated and coordinated morphogenetic cell behaviours, such as shape changes, movement, and division, which are governed by subcellular machinery and involve coupling through short- and long-range signals. A key challenge in the fields of developmental biology, tissue engineering and regeneration is to understand how relationships between scales produce emergent tissue-scale behaviours. Recent advances in molecular biology, live-imaging and ex vivo techniques have revolutionised our ability to study these processes experimentally. To fully leverage these techniques and obtain a more comprehensive understanding of the causal relationships underlying tissue dynamics, computational modelling approaches are increasingly spanning multiple spatial and temporal scales, and are coupling cell shape, growth, mechanics and signalling. Yet such models remain technically challenging: modelling at each scale requires different areas of technical skills, while integration across scales necessitates the solution to novel mathematical and computational problems. This review aims to summarise recent progress in multiscale modelling of multicellular tissues and to highlight ongoing challenges associated with the construction, implementation, interrogation and validation of such models.

The Quarrel of Policy Advisers That Became Development Experts: Currie and Hirschman in Colombia

Lauchlin Currie and Albert O. Hirschman worked together as advisers to the National Planning Council in Colombia in the 1950s. Both had little experience in development economics when they arrived, and did not see eye to eye about the functioning and policy recommendations of the council. Retracing their debates on internal and public issues using archival sources shows how the Colombian experience marked their views on the role of policy advisers, development policy, and the obstacles to development processes. Our main contribution is to show how this experience contributed to form their theories of development, which evolved from technical discussions on growth mechanics to the necessity of adopting a development strategy dealing with issues of political economy.

Research on Design and Method to Predict Fatigue Life of an Anti-Vibration Mount

In Industry almost all the machinery are subjected to noise, shocks and vibrations when machines are working. These vibrations leads to more frequent repairs and replacements of machine parts also reduce their life span. Antivibration mount is used as a Vibration Control Solutions for machineries. This work is more focused on the importance of anti-vibration mount, which can be used for various mechanical system. This study includes the design of mounts for various functional requirements and fatigue life prediction methods. There are several approaches to predict the fatigue life of mount. Initially, different types of failures in anti-vibration mounts are discussed in detail. Analytical method, Finite Element Method and Experimental approach to predict the fatigue life are analyzed. The strain life approach is considered, incorporate with material properties of mount and another approaches were discussed that are harmonic response, crack nucleation and crack growth mechanics. It is conclude with, the strain life approach is convenient method to predict the fatigue life of antivibration mount, because it give highly non-linear effect to find the critical region of mount

Experimental and theoretical studies of tumor growth

Most biological phenomena commonly involve growth and expansion mechanics. In this work, we propose an innovative model of cancerous growth which posits that an expandable tumor can be described as a poroelastic medium consisting of solid and fluid components. To verify the feasibility of the model, we utilized an established epithelial human breast cancer cell line (MDA-MB-231) to generate an in vitro tumorsphere system to observe tumor growth patterns in both constrained and unconstrained growth environments. The tumorspheres in both growth environments were grown with and without the FDA-approved anti-breast cancer anthracycline, Doxorubicin (Dox), in order to observe the influence small molecule drugs have on tumor-growth mechanics. In our biologically informed mechanical description of tumor growth dynamics, we derive the governing equations of the tumor’s growth and incorporate them with large deformation to improve the accuracy and efficiency of our simulation. Meanwhile, the dynamic finite element equations (DFE) for coupled displacement field and pressure field are formulated. Moreover, the porosity and growth tensor are generalized to be functions of displacement and pressure fields. We also introduce a specific porosity and growth tensor. In both cases, the formalism of continuum mechanics and DFE are accompanied by accurate numerical simulations.

Mathematical principles and models of plant growth mechanics: from cell wall dynamics to tissue morphogenesis

Plant growth research produces a catalogue of complex open questions. We argue that plant growth is a highly mechanical process, and that mathematics gives an underlying framework with which to probe its fundamental unrevealed mechanisms. This review serves to illustrate the biological insights afforded by mathematical modelling and demonstrate the breadth of mathematically rich problems available within plant sciences, thereby promoting a mutual appreciation across the disciplines. On the one hand, we explain the general mathematical principles behind mechanical growth models; on the other, we describe how modelling addresses specific problems in microscale cell wall mechanics, tip growth, morphogenesis, and stress feedback. We conclude by identifying possible future directions for both biologists and mathematicians, including as yet unanswered questions within various topics, stressing that interdisciplinary collaboration is vital for tackling the challenge of understanding plant growth mechanics.