Editorial highlights

Abstract

Every organism is a model organism for understanding development, evolution, disease, and regeneration, and we have only begun to scratch the surface of the interdisciplinary genetic, molecular, cellular, and developmental mechanisms that regulate these biological processes. These “Highlights” denote exciting advances recently reported in Developmental Dynamics that illustrate the complex dynamics of developmental biology.

Cell Differentiation “Emerging biological functions of Twist1 in cell differentiation” by Mengjie Tu, Bingqian Ge, Jiali Li, Yanbing Pan, Binbin Zhao, Jiayang Han, Jialin Wu, Kaifeng Zhang, Guangchao Liu, Mengwen Hou, Man Yue, Xu Han, Tiantian Sun and Yang An DevDyn 254.1, pp. 8–25. https://doi.org/10.1002/dvdy.736. Twist1 is a basic helix–loop–helix (bHLH) transcription factor, first identified in Drosophila as a crucial regulator of mesoderm development. Twist1 is evolutionarily highly conserved and can induce epithelial–mesenchymal transition (EMT) during development and in the pathogenesis of cancer metastasis. Twist1, therefore, plays a key role in a variety of developmental processes, including mesoderm formation, neurulation, neural crest cell formation, neurogenesis, and organogenesis. This review article discusses the physiological roles of Twist1 in osteogenic, chondrogenic, and myogenic differentiation and the molecular mechanisms and signaling pathways mediated by Twist1. In addition, it summarizes the structure of Twist1, its post-translational regulation, and roles in developmental disorders and diseases, with a focus on cellular differentiation. Finally, the authors consider Twist1 as a biomarker for mesenchymal stem cells and speculate that stem cell fate can be regulated through metabolic reprogramming as part of a discussion of new strategies for clinical research involving Twist1 as a regulator of EMT and in organogenesis.

Craniofacial Biology “Transcription factor Meis1b regulates craniofacial morphogenesis in zebrafish” by Viktorie Psutkova, Petr Nickl, Veronika Brezinova, Olga Machonova and Ondrej Machon DevDyn 254.1, pp. 40–60. https://doi.org/10.1002/dvdy.731. The vertebrate skull is composed of the viscerocranium (splanchnocranium), chondrocranium (neurocranium), and dermatocranium, and the co-ordinated development of tendons, muscles, nerves, cartilage, and bone are necessary for proper jaw formation and functional integration with the skull. MEIS transcription factors (MEIS1, MEIS2, MEIS3) regulate cartilage and bone development during development in mammals such as mice. This study focuses on the key roles of Meis transcription factors in zebrafish craniofacial. Zebrafish have six meis genes as the zebrafish genome contains two paralogs of each meis gene due to whole genome duplication in teleosts. The authors generated meis1a, meis1b, meis2a, and meis2b mutant zebrafish and analyzed their craniofacial skeleton. The meis genes do not influence neural crest cell development and migration, but are important for chondrocyte organization, which determines the shape and size of the jaw cartilage. The meis genes were also found to influence muscle and tendon patterning. These new zebrafish mutants may therefore serve as models of human developmental disorders, particularly those of the head and face, and especially the jaw.

Developmental Ecology “Developmental ecology in embryos of an estuarine pupfish endemic of the Yucatan peninsula: Survival out of water, metabolic depression, and asynchronous hatching” by Omar Domínguez-Castanedo and Sharon Valdez-Carbajal DevDyn 254.1, pp. 61–73. https://doi.org/10.1002/dvdy.732. Ecosystems at the margins of water and land present considerable and often unpredictable challenges for the resident organisms. Their survival may depend upon prevailing tide or rainfall patterns and involve periodic desiccation. The interface of land and water ecosystems therefore constitutes a highly variable environment with frequent abrupt and dramatic changes that promote the evolution of extreme life history strategies in small organisms that cannot migrate in search of environments with more favorable conditions. Current dogma in the field posits that drought-resistant embryos with lengthy incubation periods are evolutionarily favored in environments with high mortality of larvae but safe for eggs. Therefore, the authors tested the effect of incubation temperature and media on embryonic development length, as well as the consequences of extended incubation out of water, together with the analyses of the survival, metabolic rates, and hatching dynamics of the estuarine pupfish Garmanella pulchra. The authors found that in the absence of water, and at low or moderate temperatures, pupfish embryos exhibited an incubation period that was longer than under aquatic conditions. This capacity is centered around deep metabolic depression. Thus, a continuum involving delayed hatching and diapause facilitate the survival of pupfish during low tides in the estuaries of Yucatán they inhabit.