Positional Information—A concept underpinning our understanding of developmental biology

Comparative Analysis of Bivalve and Sea Urchin Genetics and Development: Investigating the Dichotomy in Bilateria

This comprehensive review presents a comparative analysis of early embryogenesis in Protostomia and Deuterostomia, the first of which exhibit a mosaic pattern of development, where cells are fated deterministically, while Deuterostomia display a regulatory pattern of development, where the fate of cells is indeterminate. Despite these fundamental differences, there are common transcriptional mechanisms that underline their evolutionary linkages, particularly in the field of functional genomics. By elucidating both conserved and unique regulatory strategies, this review provides essential insights into the comparative embryology and developmental dynamics of these groups. The objective of this review is to clarify the shared and distinctive characteristics of transcriptional regulatory mechanisms. This will contribute to the extensive areas of functional genomics, evolutionary biology and developmental biology, and possibly lay the foundation for future research and discussion on this seminal topic.

Collective behavior and self-organization in neural rosette morphogenesis

Neural rosettes develop from the self-organization of differentiating human pluripotent stem cells. This process mimics the emergence of the embryonic central nervous system primordium, i.e., the neural tube, whose formation is under close investigation as errors during such process result in severe diseases like spina bifida and anencephaly. While neural tube formation is recognized as an example of self-organization, we still do not understand the fundamental mechanisms guiding the process. Here, we discuss the different theoretical frameworks that have been proposed to explain self-organization in morphogenesis. We show that an explanation based exclusively on stem cell differentiation cannot describe the emergence of spatial organization, and an explanation based on patterning models cannot explain how different groups of cells can collectively migrate and produce the mechanical transformations required to generate the neural tube. We conclude that neural rosette development is a relevant experimental 2D in-vitro model of morphogenesis because it is a multi-scale self-organization process that involves both cell differentiation and tissue development. Ultimately, to understand rosette formation, we first need to fully understand the complex interplay between growth, migration, cytoarchitecture organization, and cell type evolution.

'Not birth, marriage or death, but gastrulation': the life of a quotation in biology

This history of a statement attributed to the developmental biologist Lewis Wolpert exemplifies the making and uses of quotations in recent science. Wolpert's dictum, 'It is not birth, marriage or death, but gastrulation which is truly the most important time in your life', was produced in a series of international shifts of medium and scale. It originated in his vivid declaration in conversation with a non-specialist at a workshop dinner, gained its canonical form in a colleague's monograph, and was amplified as a quotation on a poster derived from an undergraduate project. Although it drew on Wolpert's authority and he accepted his authorship, it thus represents a collective sifting of earlier claims for the significance of prenatal existence through the values of 1980s developmental biology. Juxtaposing a technical term with major life events has let teachers engage students, and researchers entice journalists, while sharing an in-joke that came to mark community identity. Serious applications include arguing for an extension of the fourteen-day limit on human-embryo research. On this evidence, quotations have been kept busy addressing every audience of specialized knowledge.

Sculpting the surface: Structural patterning of plant epidermis

Plant epidermis are multifunctional surfaces that directly affect how plants interact with animals or microorganisms and influence their ability to harvest or protect from abiotic factors. To do this, plants rely on minuscule structures that confer remarkable properties to their outer layer. These microscopic features emerge from the hierarchical organization of epidermal cells with various shapes and dimensions combined with different elaborations of the cuticle, a protective film that covers plant surfaces. Understanding the properties and functions of those tridimensional elements as well as disentangling the mechanisms that control their formation and spatial distribution warrant a multidisciplinary approach. Here we show how interdisciplinary efforts of coupling modern tools of experimental biology, physics, and chemistry with advanced computational modeling and state-of-the art microscopy are yielding broad new insights into the seemingly arcane patterning processes that sculpt the outer layer of plants.

Lewis Wolpert (1929-2021)

Lewis Wolpert was a brilliant and inspiring scientist who made hugely significant contributions which underpin and influence our understanding of developmental biology today. He spent his career interested in how the fertilised egg can give rise to the whole embryo (and ultimately the adult) with one head, two arms, two legs, all its organs and importantly how cells become different from each other and how they 'know' what to become. His ideas revolutionised the way developmental biology was perceived and also reinvigorated, in particular, the key question of how pattern formation in embryonic development is achieved. He published over 200 scientific articles and received many accolades over his career for his work and services to science in the UK. These included a CBE (Commander of the Order of the British Empire) from the Queen, being elected a Fellow of the Royal Society and a Fellow of the Royal Society of Literature. He was also a recipient of the Waddington Medal from the British Society for Developmental Biology and was awarded The Royal Society's top honour, the Royal Medal in 2018. Lewis was also a gifted teacher and communicator, including being the author of a textbook on developmental biology used around the world to train the next generation of developmental biologists. This contribution was recognised in 2003, by the award of the Viktor Hamburger Outstanding Educator Award from the Society of Developmental Biology in the USA. Lewis always enjoyed giving talks and lectures, having an infectious and persuasive enthusiasm coupled with a sharp sense of humour. He also published articles in popular science journals (aimed at the public) such as New Scientist, Scientific American and The Scientist. Lewis also wrote several popular science books. He was a passionate advocate for the public understanding of science and was the Chair of The Royal Society/Royal Institution/British Association for the Advancement of Science Committee for Public Understanding of Science (1994-1998). For this contribution he was awarded The Royal Society Michael Faraday Medal for "excellence in communicating science to UK audiences". He presented the prestigious Royal Institution Christmas Lectures in 1986 entitled 'Frankenstein's Quest: development of life'. These lectures, six in total, are presented by leading scientists and aimed at the general public and broadcast on national television. On a personal level, Lewis influenced all who came into contact with him, shaped his students and postdocs careers and instilled in them, and the community as whole, a life-long love of developmental biology.

Establishing the pattern of the vertebrate limb

The vertebrate limb continues to serve as an influential model of growth, morphogenesis and pattern formation. With this Review, we aim to give an up-to-date picture of how a population of undifferentiated cells develops into the complex pattern of the limb. Focussing largely on mouse and chick studies, we concentrate on the positioning of the limbs, the formation of the limb bud, the establishment of the principal limb axes, the specification of pattern, the integration of pattern formation with growth and the determination of digit number. We also discuss the important, but little understood, topic of how gene expression is interpreted into morphology.

Hydra: A Powerful Biological Model

Hydra, a freshwater diploblast, with a simple but defined body plan, an organized nervous system, and the presence of stem cells, is one of the oldest model organisms used in biology. It exhibits many embryonic features even as an adult, a spectacular ability of regeneration, and lack of organismal aging. Hydra can provide insights into how complex animal forms evolved and is waiting to be better utilized in teaching.