Developmental Biology Community Research Articles

Deciphering lineage specification during early embryogenesis in mouse gastruloids using multilayered proteomics.

Gastrulation is a critical stage in embryonic development during which the germ layers are established. Advances in sequencing technologies led to the identification of gene regulatory programs that control the emergence of the germ layers and their derivatives. However, proteome-based studies of early mammalian development are scarce. To overcome this, we utilized gastruloids and a multilayered mass spectrometry-based proteomics approach to investigate the global dynamics of (phospho) protein expression during gastruloid differentiation. Our findings revealed many proteins with temporal expression and unique expression profiles for each germ layer, which we also validated using single-cell proteomics technology. Additionally, we profiled enhancer interaction landscapes using P300 proximity labeling, which revealed numerous gastruloid-specific transcription factors and chromatin remodelers. Subsequent degron-based perturbations combined with single-cell RNA sequencing (scRNA-seq) identified a critical role for ZEB2 in mouse and human somitogenesis. Overall, this study provides a rich resource for developmental and synthetic biology communities endeavoring to understand mammalian embryogenesis.

TubULAR: tracking in toto deformations of dynamic tissues via constrained maps.

A common motif in biology is the arrangement of cells into tubes, which further transform into complex shapes. Traditionally, analysis of dynamic tissues has relied on inspecting static snapshots, live imaging of cross-sections or tracking isolated cells in three dimensions. However, capturing the interplay between in-plane and out-of-plane behaviors requires following the full surface as it deforms and integrating cell-scale motions into collective, tissue-scale deformations. Here, we present an analysis framework that builds in toto maps of tissue deformations by following tissue parcels in a static material frame of reference. Our approach then relates in-plane and out-of-plane behaviors and decomposes complex deformation maps into elementary contributions. The tube-like surface Lagrangian analysis resource (TubULAR) provides an open-source implementation accessible either as a standalone toolkit or as an extension of the ImSAnE package used in the developmental biology community. We demonstrate our approach by analyzing shape change in the embryonic Drosophila midgut and beating zebrafish heart. The method naturally generalizes to in vitro and synthetic systems and provides ready access to the mechanical mechanisms relating genetic patterning to organ shape change.

Automated staging of zebrafish embryos with deep learning.

The zebrafish (Danio rerio) is an important biomedical model organism used in many disciplines. The phenomenon of developmental delay in zebrafish embryos has been widely reported as part of a mutant or treatment-induced phenotype. However, the detection and quantification of these delays is often achieved through manual observation, which is both time-consuming and subjective. We present KimmelNet, a deep learning model trained to predict embryo age (hours post fertilisation) from 2D brightfield images. KimmelNet's predictions agree closely with established staging methods and can detect developmental delays between populations with high confidence using as few as 100 images. Moreover, KimmelNet generalises to previously unseen data, with transfer learning enhancing its performance. With the ability to analyse tens of thousands of standard brightfield microscopy images on a timescale of minutes, we envisage that KimmelNet will be a valuable resource for the developmental biology community. Furthermore, the approach we have used could easily be adapted to generate models for other organisms.

Juan Modolell (1937-2023).

Juan Modolell (1937-2023).

Lifting the cloche: Jeroen Bakkers interviews Didier Stainier.

Didier Stainier is Director of the Department of Developmental Genetics at the Max Planck Institute for Heart and Lung Research in Bad Nauheim, Germany. He became acquainted with the zebrafish model as a PhD student in Walter Gilbert's lab at Harvard, which motivated him to champion the use of this powerful model organism to study heart development as a postdoctoral fellow with Mark Fishman at Massachusetts General Hospital. Although his scientific focus has expanded significantly since then, zebrafish modelling and heart development and regeneration remain key topics in his research. The developmental biology and zebrafish modelling communities have embraced him as an inspiring mentor and advocate for basic research. Jeroen Bakkers is a group leader at the Hubrecht Institute for Developmental Biology and Stem Cell Research and Professor of Molecular Cardiogenetics at the University Medical Center Utrecht, The Netherlands. Jeroen did hid PhD with Herman Spaink at Leiden University, The Netherlands. A short visit to Massachusetts Institute of Technology during his doctoral training introduced him to the zebrafish model, which he applied to his PhD project. Zebrafish development remained the focus of his career, including during his postdoctoral training in the lab of Matthias Hammerschmidt at the Max Planck Institute of Immunology and Epigenetics in Freiburg and in his own lab at the Hubrecht Institute, where his group uses this powerful model organism to investigate cardiac development, disease and regeneration. Jeroen and Didier met up at a recent conference to talk about their shared interest in cardiac regeneration, a zebrafish mutant with a curious name and Didier's commitment to mentorship.

Preprint Highlight: ERK-mediated curvature feedback regulates branching morphogenesis in lung epithelial tissue

During development, cells operate in a complex geometrical environment. Geometry can inform morphogenesis by patterning mechanical and chemical signals. Yet, how this feedback occurs remains elusive. Using elegant imaging tools, mechanical perturbation, and modeling, the authors show that positive tissue curvature defines the site of highest ERK activity in lung epithelium. In turn, ERK dampens the curvature by promoting actin-mediated apical extension of cells. This negative feedback loop generates the branching pattern in developing lungs. These findings reinforce the notion that tissue geometry is necessary to comprehensively understand and recapitulate morphogenesis. This study will appeal to the broad cell and developmental biology community, as well as labs focusing on tissue engineering and in vitro organ models.

Preprint Highlight: Dynamic interplay of protrusive microtubule and contractile actomyosin forces drive tissue extension.

Cytoskeletal mechanical forces shape tissues during development. Although the role of the actomyosin machinery is extensively studied, how microtubules actively generate forces to shape tissues remains unknown. Combining in vivo experiments and simulations, this study elucidates that initial cell elongation during fly wing development is not driven by myosin contractility or external forces. Instead, protrusive forces generated by planar polarized noncentrosomal microtubules actively drive cell elongation, while myosin contractility is needed for final cell shape refinement. Thus ordered coordination between microtubules and actomyosin shapes the fly wing. This study will appeal to the broad cell and developmental biology community as it strengthens the growing notion that microtubules are active morphogenetic effectors. Beyond their core functions in cell division and intracellular transport, microtubule-mediated forces can directly dictate cell and tissue shape during development.

Preprint Highlight: Intertissue mechanical interactions shape the olfactory circuit in zebrafish.

How the mechanics of surrounding tissue regulate tissue morphogenesis in vivo is not well known. This study addresses this problem by studying the developing olfactory placodes in zebrafish, a sensory organ which later gives rise to the opening of the nose. Combining this highly tractable system with quantitative live imaging, genetics, and biophysical manipulations, the authors reveal that the extracellular matrix transmits mechanical cues from the developing eye to the adjacent olfactory placode, thereby coupling their morphogenesis. This study will appeal to the broad cell and developmental biology community as it strengthens the fundamental notion that the emergence of form during embryogenesis does not happen in isolation and relies on the surrounding physical cues and interactions with adjacent tissues.

The Biological Robots Are Coming! But Note They Have Been Here for ∼3.5 Billion Years

The Biological Robots Are Coming! But Note They Have Been Here for ∼3.5 Billion Years

The future of conferences.

The future of conferences.

The rise of developmental biology in China.

Developmental biology research in China started from experimental embryology, in particular from studies on aquatic and reptile animals. The recent growth of the developmental biology community in China parallels the increased governmental funding support and the recruitment of overseas talents. This flourishing field in China embraces the activities of developmental biology-related societies, national meetings, key research initiatives and talented scientists. The first Development paper from China, published in 2000, marked the beginning of a new era. More recently, the second decade in the 21st century witnessed the blossoming of developmental biology research in China. Significant research spotlights, technical advances, and up-and-coming areas will be discussed in this overview.

Quantitative developmental biology in vitro using micropatterning.

ABSTRACTMicropatterning encompasses a set of methods aimed at precisely controlling the spatial distribution of molecules onto the surface of materials. Biologists have borrowed the idea and adapted these methods, originally developed for electronics, to impose physical constraints on biological systems with the aim of addressing fundamental questions across biological scales from molecules to multicellular systems. Here, I approach this topic from a developmental biologist's perspective focusing specifically on how and why micropatterning has gained in popularity within the developmental biology community in recent years. Overall, this Primer provides a concise overview of how micropatterns are used to study developmental processes and emphasises how micropatterns are a useful addition to the developmental biologist’s toolbox.

Wolpert's French Flag: what's the problem?

Two phrases attributed to Lewis Wolpert - 'positional information' and 'The French Flag Model' - have become so intertwined that they are now used almost interchangeably. Here, I argue that this represents an unfortunate oversimplification of Wolpert's ideas that arose gradually in the developmental biology community, some significant time after his key papers were published. In contrast to common belief, Wolpert did not use the phrase French Flag 'Model' but instead introduced the French Flag 'Problem'. This famous metaphor was not a proposal of how patterning works, but rather an abstraction of the question to be addressed. More specifically, the French flag metaphor was an attempt to de-couple the problem from the multiple possible models that could solve it. In this spirit, Wolpert's first article on this topic also proposed (in addition to the well-known gradient model) an alternative solution to the French Flag Problem that was self-organising and had no gradients, and in which each cell 'cannot compute where it is in the system', i.e. there is no positional information. I discuss the history and evolution of these terms, and how they influence the way we study patterning.

Isolation of nanobodies against Xenopus embryonic antigens using immune and non-immune phage display libraries.

The use of Xenopus laevis as a model for vertebrate developmental biology is limited by a lack of antibodies specific for embryonic antigens. This study evaluated the use of immune and non-immune phage display libraries for the isolation of single domain antibodies, or nanobodies, with specificities for Xenopus embryonic antigens. The immune nanobody library was derived from peripheral blood lymphocyte RNA obtained from a llama immunized with Xenopus gastrula homogenates. Screening this library by immunostaining of embryonic tissues with pooled periplasmic material and sib-selection led to the isolation of several monoclonal phages reactive with the cytoplasm and nuclei of gastrula cells. One antigen recognized by a group of nanobodies was identified using a reverse proteomics approach as nucleoplasmin, an abundant histone chaperone. As an alternative strategy, a semi-synthetic non-immune llama nanobody phage display library was panned on highly purified Xenopus proteins. This proof-of-principle approach isolated monoclonal nanobodies that specifically bind Nuclear distribution element-like 1 (Ndel1) in multiple immunoassays. Our results suggest that immune and non-immune phage display screens on crude and purified embryonic antigens can efficiently identify nanobodies useful to the Xenopus developmental biology community.

Improving the visibility of developmental biology: time for induction and specification.

Developmental biology is a prominent field that has captured the imagination of many scientists. Over the years, research in the area has seen a steady number of amazing accomplishments, with peaks in activity following the development and application of new technologies. Although the field continues to flourish and produce excellent work, I have recently noticed difficulty with its perception and visibility. Having joined the developmental biology community during the early 1990s, and contributing since as a stem cell researcher, cancer biologist and an MD, I have a unique perspective on these challenges. Here, I discuss these issues and challenges and offer potential solutions for a field that is very important to me.

Recovery continues for developmental biology community in Puerto Rico

Recovery continues for developmental biology community in Puerto Rico

A "Brief History" of Developmental Biology in Israel.

While the history of developmental biology in Israel is relatively short, its impact is far-reaching, so we wanted to present a concise perspective on the Israeli developmental biology community, past-present-future. This community has undergone a wonderful, nearly exponential growth over the last three decades. How exactly did this happen? There are approximately fifty research groups that focus on developmental biology questions in Israel today that are members of the Israel Society of Developmental Biology (IsSDB; http://issdb.org/). The community has representative groups in a plethora of model systems, such as Nematostella, C. elegans, Drosophila, sea urchin, ascidians, zebrafish, Xenopus, chick and mouse, as well as plants, representing all the major universities and their branches, which include Bar-Ilan University, Ben-Gurion University of the Negev, The Hebrew University of Jerusalem, The University of Haifa, Technion - Israel Institute of Technology, Tel Aviv University and the Weizmann Institute of Science.

The Childhood Solid Tumor Network: A new resource for the developmental biology and oncology research communities

Significant advances have been made over the past 25 years in our understanding of the most common adult solid tumors such as breast, colon, lung and prostate cancer. Much less is known about childhood solid tumors because they are rare and because they originate in developing organs during fetal development, childhood and adolescence. It can be very difficult to study the cellular origins of pediatric solid tumors in developing organs characterized by rapid proliferative expansion, growth factor signaling, developmental angiogenesis, programmed cell death, tissue reorganization and cell migration. Not only has the etiology of pediatric cancer remained elusive because of their developmental origins, but it also makes it more difficult to treat. Molecular targeted therapeutics that alter developmental pathway signaling may have devastating effects on normal organ development. Therefore, basic research focused on the mechanisms of development provides an essential foundation for pediatric solid tumor translational research. In this article, we describe new resources available for the developmental biology and oncology research communities. In a companion paper, we present the detailed characterization of an orthotopic xenograft of a pediatric solid tumor derived from sympathoadrenal lineage during development.

StemChecker: a web-based tool to discover and explore stemness signatures in gene sets.

Stem cells present unique regenerative abilities, offering great potential for treatment of prevalent pathologies such as diabetes, neurodegenerative and heart diseases. Various research groups dedicated significant effort to identify sets of genes—so-called stemness signatures—considered essential to define stem cells. However, their usage has been hindered by the lack of comprehensive resources and easy-to-use tools. For this we developed StemChecker, a novel stemness analysis tool, based on the curation of nearly fifty published stemness signatures defined by gene expression, RNAi screens, Transcription Factor (TF) binding sites, literature reviews and computational approaches. StemChecker allows researchers to explore the presence of stemness signatures in user-defined gene sets, without carrying-out lengthy literature curation or data processing. To assist in exploring underlying regulatory mechanisms, we collected over 80 target gene sets of TFs associated with pluri- or multipotency. StemChecker presents an intuitive graphical display, as well as detailed statistical results in table format, which helps revealing transcriptionally regulatory programs, indicating the putative involvement of stemness-associated processes in diseases like cancer. Overall, StemChecker substantially expands the available repertoire of online tools, designed to assist the stem cell biology, developmental biology, regenerative medicine and human disease research community. StemChecker is freely accessible at http://stemchecker.sysbiolab.eu.

Atlas-builder software and the eNeuro atlas: resources for developmental biology and neuroscience.

A major limitation in understanding embryonic development is the lack of cell type-specific markers. Existing gene expression and marker atlases provide valuable tools, but they typically have one or more limitations: a lack of single-cell resolution; an inability to register multiple expression patterns to determine their precise relationship; an inability to be upgraded by users; an inability to compare novel patterns with the database patterns; and a lack of three-dimensional images. Here, we develop new 'atlas-builder' software that overcomes each of these limitations. A newly generated atlas is three-dimensional, allows the precise registration of an infinite number of cell type-specific markers, is searchable and is open-ended. Our software can be used to create an atlas of any tissue in any organism that contains stereotyped cell positions. We used the software to generate an 'eNeuro' atlas of the Drosophila embryonic CNS containing eight transcription factors that mark the major CNS cell types (motor neurons, glia, neurosecretory cells and interneurons). We found neuronal, but not glial, nuclei occupied stereotyped locations. We added 75 new Gal4 markers to the atlas to identify over 50% of all interneurons in the ventral CNS, and these lines allowed functional access to those interneurons for the first time. We expect the atlas-builder software to benefit a large proportion of the developmental biology community, and the eNeuro atlas to serve as a publicly accessible hub for integrating neuronal attributes - cell lineage, gene expression patterns, axon/dendrite projections, neurotransmitters--and linking them to individual neurons.