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.

Fat in Development and Disease “Deciphering adipose development: Function, differentiation and regulation”, by Ge Guo, Wanli Wang, Mengjie Tu, Binbin Zhao, Jiayang Han, Jiali Li, Yanbing Pan, Jie Zhou, Wen Ma, Yi Liu, Tiantian Sun, Xu Han, and Yang An DevDyn 253:11, pp. 956–997. https://doi.org/10.1002/dvdy.708. Nearly 1 in every 8 humans worldwide are afflicted with obesity. That's more than 1 billion people. Characterized by excessive adiposity, obesity is a major risk factor for human diseases such as hypertension, osteoarthritis, diabetes and cancer. Adipose tissue, which is characterized as white adipose tissue, or brown adipose tissue, is located in subcutaneous and visceral regions and mainly composed of adipocytes. Excessive lipid accumulation is mediated by adipocyte hypertrophy (increase in adipocyte size) or adipocyte hyperplasia (increase in adipocyte number). During embryogenesis and adult homeostasis, adipogenesis is governed by many factors including hormones, cytokines, diet and even sex. This review provides a detailed description of adipose development, focusing on its origin, classification, distribution and function. Activating brown adipose tissue thermogenic activity and facilitating the conversion of white adipose tissue into beige adipose tissue is a promising strategy for antagonizing obesity but comes with side effects and risks. Therefore, preventing obesity without impairing adipose tissue function requires a deeper understanding of the molecular mechanisms that govern adipogenesis.

Body Plan Patterning and Segmentation “Muscular remodeling and anteroposterior patterning during tapeworm segmentation” by Francesca Jarero, Andrew Baillie, Nick Riddiford, Jimena Montagne, Uriel Koziol and Peter Olson DevDyn 253:11, pp. 998–1023. https://doi.org/10.1002/dvdy.712. The evolution of segmentation is thought to have facilitated the efficient generation of repeat structural or anatomical units along the anterior-posterior axis of an organism. Considered a major evolutionary innovation, arthropods, annelids and chordates all possess segments, but whether or not these instances of segmentation are homologous, has remained contentious. Tapeworms are one of the oldest recognized forms of parasitic flatworms, and their segmented body plan that evolved independently, has historically confounded comparisons with other organisms. This study therefore investigated positional control gene expression in the neck region of the mouse bile-duct tapeworm H. microstoma. During initial segmental patterning of the adult body, the adult musculature includes new, segmental elements that first appear in the neck. Furthermore, the appearance of muscle cells correlates with the spatiotemporal expression of Wnt signaling factors. Therefore, segmentation in tapeworms could originate in the muscular system and participate in patterning the anterioposterior axis through regional and polarized expression of positional control genes. This could be analogous to the gene regulatory networks employed by free-living flatworms and other animals.

Zebrafish Spinal Cord Development and Transgenesis “Transcriptional regulators with broad expression in the zebrafish spinal cord” by Samantha England, Paul Campbell, Santanu Banerjee, Richard Bates, Ginny Grieb, William Fancher and Katharine Lewis DevDyn 253:11, pp. 1036–1055. https://doi.org/10.1002/dvdy.717. The spinal cord is part of the central nervous system and is responsible for sending motor commands from the brain to the body, relaying sensory information from the body to the brain, and coordinating reflexes. In an effort to better understand how the spinal cord develops, how neuronal and glial spinal cell types are made, maintained and connected into appropriate neuronal circuitry, the authors undertook a gene expression screen to identify transcription factor and transcriptional regulator genes that are expressed in the developing spinal cord. Some genes were expressed in progenitor cells, others in both progenitor cells and different subsets of post-mitotic cells, whereas others were predominantly expressed in distinct subtypes of post-mitotic cells. The identification of 22 genes with broad expression in the zebrafish embryonic spinal cord, some of which had never been previously described, lays an important foundation for determining the gene regulatory networks that govern the formation of neural circuitry and spinal cord function.

“Rapid generation of single-insertion transgenics by Tol2 transposition in zebrafish” by Miglė Kalvaitytė, Sofija Gabrilavičiūtė and Darius Balciunas DevDyn 253:11, pp. 1056–1065. https://doi.org/10.1002/dvdy.719. Transposons are natural DNA transfer vehicles that enable efficient and precise integration of foreign DNA into genomes. Transposons facilitate high germline transmission rates and single-copy transgene integration. The growing demand for streamlined genetic modifications in zebrafish have driven significant advancements in Tol2 transgenesis. This study describes modifications to the standard Tol2-mediated transgenesis protocol by diluting the vector carrying the transgene of interest with a “competitor” Tol2 vector marked with a fluorescent reporter for counter selection. This approach reduces the number of integrated transgene cassettes into the zebrafish genome, allowing for the successful generation of multiple independent single-insertion transgenic lines in the F1 generation. By bypassing the need for multi-generational breeding, this improved approach has the potential to reduce animal usage and save time while also enhancing reproducibility and distribution of single-insertion transgenic lines.