Highlights in DD

Abstract

“Highlights” calls attention to exciting advances in developmental biology that have recently been reported in Developmental Dynamics. Development is a broad field encompassing many important areas. To reflect this fact, the section spotlights significant discoveries that occur across the entire spectrum of developmental events and problems: from new experimental approaches, to novel interpretations of results, to noteworthy findings utilizing different developmental organisms. Leveling the playing field (New Frontiers in Cell Competition by Simon de Beco, Marcello Ziosi, and Laura A. Johnston, Dev Dyn 241:831–841) In a world that is competitive by nature, even cells elbow out the weak. In cell competition, cells get the stats on the their neighbors' fitness by sensing and responding to their growth rates. “Losing”” cells undergo apoptosis, regulating overall organ homeostasis and growth, a process most intensely studied in growing Drosophila epithelia. This review details recent experiments that identify new players that make the fight possible, including the membrane protein Flower, the extracellular protein Sparc, the signaling molecule Wg, and the Hippo-Salvador-Warts pathway. Recent data support the hypothesis that cell competition also plays a physiological role in mammalian hematopoietic cells. However there is at least one key difference: “losers”” undergo senescence rather than apoptosis. Future directions include a thorough comparison between Drosophila and mammalian cell competition, and how the process fits into other pathways such as stress resistance, stem cell expansion, and normal development. Progress will come from cooperation between mammalian and Drosophila investigators—not competition. It's normal (Normalized Shape and Location of Perturbed Craniofacial Structures in the Xenopus Tadpole Reveal an Innate Ability to Achieve Correct Morphology by Laura N. Vandenberg, Dany S. Adams, and Michael Levin, Dev Dyn 241:863–878) Embryos are incredibly forgiving. At later stages, there may be no signs of an injury sustained in early development. To gain insights into this phenomenon Vandenberg et. al, used geometric morphometric analytical techniques to determine how relative positions of Xenopus anatomical landmarks change over time following induced craniofacial perturbations. They note that while all tissues observed eventually end up back in their normal locations, the morphology of some tissues (cranial neural crest derived jaw and branchial arch) are more easily repaired than others (ectodermal placode derived—eye, nose). Further, reaching a target position is a dynamic process governed by a structure's position relative to stable reference points (distance from brain and angle from midline). The authors suggest a model in which a craniofacial structure senses its position based on signals sent between it and an “organizing center.” Uncovering the precise nature of this exchange has implications for repair of birth defects, organ regeneration, and insults sustained during adulthood.