During gastrulation, early embryos specify and reorganise the topology of their germ layers. Surprisingly, this fundamental and early process does not appear to be rigidly constrained by evolutionary pressures; instead, the morphology of gastrulation is highly variable throughout the animal kingdom. Recent experimental results demonstrate that it is possible to generate different alternative gastrulation modes in single organisms, such as in early cnidarian, arthropod and vertebrate embryos. Here, we review the mechanisms that underlie the plasticity of vertebrate gastrulation both when experimentally manipulated and during evolution. Using the insights obtained from these experiments we discuss the effects of the increase in yolk volume on the morphology of gastrulation and provide new insights into two crucial innovations during amniote gastrulation: the transition from a ring-shaped mesoderm domain in anamniotes to a crescent-shaped domain in amniotes, and the evolution of the reptilian blastoporal plate/canal into the avian primitive streak.
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http://dx.doi.org/10.1242/dev.200885 | DOI Listing |
Cells Dev
December 2024
Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France; School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
2024 not only marked the 100th anniversary of the discovery of the organizer by Hilde Pröscholdt-Mangold and Hans Spemann, but also the 40th anniversary of the discovery of the homeobox, a DNA region encoding a DNA binding peptide present in several transcription factors of critical importance for the gastrulating embryo. In particular, this sequence is found in the 39 members of the amniote Hox gene family, a series of genes activated in mid-gastrulation and involved in organizing morphologies along the extending anterior to posterior (AP) body axis. Over the past 30 years, the study of their coordinated regulation in various contexts has progressively revealed their surprising regulatory strategies, based on mechanisms acting in-cis, which can translate a linear distribution of series of genes along the chromatin fiber into the proper sequences of morphologies observed along our various body axes.
View Article and Find Full Text PDFInt J Dev Biol
December 2024
Department of Embryology, Institute of Developmental Biology and Biomedical Sciences, Faculty of Biology, University of Warsaw, Warsaw, Poland.
Aggregates of two mouse embryos produce viable offspring of normal size, indicating that there are mechanisms in the embryo that can downregulate their size to the size of the corresponding normal (single) embryos. Very little is known about the mechanisms controlling compensation for increased preimplantation size. Also, it is still elusive when exactly during development chimeric embryos regulate their size.
View Article and Find Full Text PDFElife
December 2024
Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, United States.
Shape changes of epithelia during animal development, such as convergent extension, are achieved through the concerted mechanical activity of individual cells. While much is known about the corresponding large-scale tissue flow and its genetic drivers, fundamental questions regarding local control of contractile activity on the cellular scale and its embryo-scale coordination remain open. To address these questions, we develop a quantitative, model-based analysis framework to relate cell geometry to local tension in recently obtained time-lapse imaging data of gastrulating embryos.
View Article and Find Full Text PDFInt J Mol Sci
November 2024
Laboratory of Molecular Diagnostics and Cell Biology, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Republic of Korea.
Elife
December 2024
Department of Biology, Indian Institute of Science Education & Research, Pune, India.
Repurposing of pleiotropic factors during execution of diverse cellular processes has emerged as a regulatory paradigm. Embryonic development in metazoans is controlled by maternal factors deposited in the egg during oogenesis. Here, we explore maternal role(s) of Caspar (Casp), the orthologue of human Fas-associated factor-1 (FAF1) originally implicated in host-defense as a negative regulator of NF-κB signaling.
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