The TET-Sall4-BMP regulatory axis controls craniofacial cartilage development

p75 neurotrophin receptor regulates craniofacial growth and morphology in postnatal development

Craniofacial abnormalities are among the most prevalent congenital defects, significantly affecting appearance, function, and quality of life. While the role of genetic mutations in craniofacial malformations is recognized, the underlying molecular mechanisms remain poorly understood. In this study, we investigate the role of p75 neurotrophin receptor (p75NTR) in craniofacial development by comparing wild-type (p75NTR+/+) mice against p75NTR-deficient (p75NTR-/-) knockout mice. We employed histology, micro-CT surface distance, volumetric analysis, and geometric morphometric analysis to assess craniofacial development and growth. On postnatal day 7 (P7), p75NTR-/- mice exhibited reduced skull length compared to wild-type controls. By P28, micro-CT analysis revealed significant reductions in calvarial bone volume and trabecular bone thickness in p75NTR-/- mice. Geometric morphometric analysis identified significant shape alterations in the nasal, parietal, and occipital regions, with p75NTR-/- mice showing a shortened cranium and tapered nasal bone morphology. These findings highlight the critical role of p75NTR in regulating postnatal craniofacial development. Disruption of p75NTR signaling impairs both the growth and morphological integrity of craniofacial structures, which may contribute to the pathogenesis of congenital craniofacial abnormalities. In the future, a better understanding of the molecular mechanisms through which p75NTR mediates craniofacial development may offer valuable insights for future targeted therapeutic strategies for craniofacial defects.

Single-cell sequencing provides clues about the developmental genetic basis of evolutionary adaptations in syngnathid fishes

Seahorses, pipefishes, and seadragons are fishes from the family Syngnathidae that have evolved extraordinary traits including male pregnancy, elongated snouts, loss of teeth, and dermal bony armor. The developmental genetic and cellular changes that led to the evolution of these traits are largely unknown. Recent syngnathid genome assemblies revealed suggestive gene content differences and provided the opportunity for detailed genetic analyses. We created a single-cell RNA sequencing atlas of Gulf pipefish embryos to understand the developmental basis of four traits: derived head shape, toothlessness, dermal armor, and male pregnancy. We completed marker gene analyses, built genetic networks, and examined the spatial expression of select genes. We identified osteochondrogenic mesenchymal cells in the elongating face that express regulatory genes bmp4, sfrp1a, and prdm16. We found no evidence for tooth primordia cells, and we observed re-deployment of osteoblast genetic networks in developing dermal armor. Finally, we found that epidermal cells expressed nutrient processing and environmental sensing genes, potentially relevant for the brooding environment. The examined pipefish evolutionary innovations are composed of recognizable cell types, suggesting that derived features originate from changes within existing gene networks. Future work addressing syngnathid gene networks across multiple stages and species is essential for understanding how the novelties of these fish evolved.

Single Cell Sequencing Provides Clues about the Developmental Genetic Basis of Evolutionary Adaptations in Syngnathid Fishes

Seahorses, pipefishes, and seadragons are fishes from the family Syngnathidae that have evolved extraordinary traits including male pregnancy, elongated snouts, loss of teeth, and dermal bony armor. The developmental genetic and cellular changes that led to the evolution of these traits are largely unknown. Recent syngnathid genome assemblies revealed suggestive gene content differences and provide the opportunity for detailed genetic analyses. We created a single cell RNA sequencing atlas of Gulf pipefish embryos to understand the developmental basis of four traits: derived head shape, toothlessness, dermal armor, and male pregnancy. We completed marker gene analyses, built genetic networks, and examined spatial expression of select genes. We identified osteochondrogenic mesenchymal cells in the elongating face that express regulatory genes bmp4, sfrp1a, and prdm16. We found no evidence for tooth primordia cells, and we observed re-deployment of osteoblast genetic networks in developing dermal armor. Finally, we found that epidermal cells expressed nutrient processing and environmental sensing genes, potentially relevant for the brooding environment. The examined pipefish evolutionary innovations are composed of recognizable cell types, suggesting derived features originate from changes within existing gene networks. Future work addressing syngnathid gene networks across multiple stages and species is essential for understanding how their novelties evolved.