Editorial highlights

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.

Xenopus Ectoderm Patterning. “The sulfotransferase XB5850668.L is required to apportion embryonic ectodermal domains’ by Alexander Marchak, Karen Neilson, Himani Majumdar, Kiyoshi Yamauchi, Steven Klein and Sally Moody; DevDyn 252:12, https://doi.org/10.1002/dvdy.648. Six1 is a transcription factor required for patterning the embryonic ectoderm into neural plate, neural crest, preplacodal and epidermal domains, and mutations in SIX1 in humans are causative for Branchio-oto-renal (BOR), and Deafness, autosomal dominant 23 (DFNA23) syndromes. In this study, screening for Six1 targets identified a previously uncharacterized sulfotransferase. Sulfotransferases, catalyze the transfer of a sulfuryl (SO3) group from a donor to a substrate, and have been studied extensively in adult tissues where they play important roles in detoxifying compounds and metabolizing drugs. Loss, and gain-of-function analyses in Xenopus embryos reveals for the first time that sulfotransferases play regulate early craniofacial development by balancing the proportional specifical of the embryonic ectoderm into presumptive neural plate versus neural crest and cranial placode tissues. Variants in Sulfotransferase genes could therefore be potential new candidates for BOR and DFNA23 syndromes.

Pharyngeal Development “Foxi3GFP and Foxi3CreER mice allow identification and lineage labeling of pharyngeal arch ectoderm and endoderm, and tooth and hair placodes” by Harinarayana Ankamreddy, Ankita Thawani, Onur Birol, Hongyuan Zhang, and Andrew Groves, DevDyn 252:12; https://doi.org/10.1002/dvdy.645. Pharyngeal arches are transient embryonic structures that give rise to many craniofacial structures including the lower jaw, middle and external ears, and endoderm derived organs such as the thymus, thyroid and parathyroid. FOXI3 is a forkhead family transcription factor that is expressed in the progenitors of craniofacial placodes, epidermal placodes, and the ectoderm and endoderm of the pharyngeal arch region. This study generated new Foxi3GFP and Foxi3CreER genetic tools for studying pharyngeal development. Foxi3GFP mice recapitulate the expression patterns of Foxi3 mRNA, and Foxi3CreER mice can trace the derivatives of pharyngeal arch ectoderm and endoderm, the pharyngeal pouches and clefts that separate each arch, and the derivatives of hair and tooth placodes.

Zebrafish Metalloproteases “Dynamic and Broad Expression of adamts9 in Developing and Adult Zebrafish” by Yuanfa He, Jonathan Carver, Timothy Erickson, Pierre Le Pabic, and Yong Zhu; DevDyn 252:12, https://doi.org/10.1002/dvdy.643. Metalloproteases play important roles in morphogenesis, tissue remodeling, cell migration, and cellular signaling. This study reports the generation and characterization of a new transgenic zebrafish reporter line Tg(adamts9:EGFP) to visualize adamts9 activity at the cellular level. The expression pattern of adamts9 in embryos and adults suggests evolutionary conserved metalloprotease involvement in eye, spinal cord and ovary development, physiological function, and pathophysiological processes.