The amazing and anomalous axolotls as scientific models

NSAID-mediated cyclooxygenase inhibition disrupts ectodermal derivative formation in axolotl embryos

Embryonic exposures to non-steroidal anti-inflammatory drugs (NSAIDs) have been linked to preterm birth, neural tube closure defects, abnormal enteric innervation, and craniofacial malformations, potentially due to disrupted neural tube or neural crest (NC) cell development. Naproxen (NPX), a common non-steroidal anti-inflammatory drug (NSAID) used to relieve pain and inflammation, exerts its effects through non-selective cyclooxygenase (COX) inhibition. Our lab has identified that the cyclooxygenase (COX-1 and COX-2) isoenzymes are expressed during the early stages of vertebrate embryonic development, and that global inhibition of COX-1 and COX-2 function disrupts NC cell migration and differentiation in Ambystoma mexicanum (axolotl) embryos. NC cells differentiate into various adult tissues including craniofacial cartilage, bone, and neurons in the peripheral and enteric nervous systems. To investigate the specific phenotypic and molecular effects of NPX exposure on NC development and differentiation, and to identify molecular links between COX inhibition and NC derivative anomalies, we exposed late neurula and early tailbud stage axolotl embryos to various concentrations of NPX and performed immunohistochemistry (IHC) for markers of migratory and differentiating NC cells. Our results reveal that NPX exposure impairs the migration of SOX9+ NC cells, leading to abnormal development of craniofacial cartilage structures, including Meckel's cartilage in the jaw. NPX exposure also alters the expression of markers associated with peripheral and central nervous system (PNS and CNS) development, suggesting concurrent neurodevelopmental changes.

Connecting Bone Remodeling and Regeneration: Unraveling Hormones and Signaling Pathways

Recent advancements in tissue engineering and stem cell science have positioned bone disease treatment as a promising frontier in regenerative medicine. This review explores the hormonal and signaling pathways critical to bone regeneration, with a focus on their clinical relevance. Key endocrine factors, including thyroid hormones (T3 and T4), insulin-like growth factor 1 (IGF-1), bone morphogenetic proteins (BMPs), parathyroid hormone (PTH), calcitonin, and fibroblast growth factor 23 (FGF23), play pivotal roles in bone remodeling by regulating osteoblast activity, bone resorption, and mineralization. These factors primarily act through the Wnt/β-catenin, BMP, and FGF signaling pathways, which govern bone repair and regeneration. While animal models, such as axolotls, zebrafish, and Xenopus laevis, provide valuable findings about these mechanisms, translating these findings into human applications presents challenges. This review underscores the therapeutic potential of modulating these hormonal networks to enhance bone regeneration while cautioning against possible adverse effects, such as uncontrolled tissue proliferation or metabolic imbalances. By integrating knowledge from regenerative models, this work provides a foundation for optimizing hormone-based therapies for clinical applications in bone repair and disease treatment.

NSAID-mediated cyclooxygenase inhibition disrupts ectodermal derivative formation in axolotl embryos

Embryonic exposures to non-stseroidal anti-inflammatory drugs (NSAIDs) have been linked to preterm birth, neural tube closure defects, abnormal enteric innervation, and craniofacial malformations, potentially due to disrupted neural tube or neural crest (NC) cell development. Naproxen (NPX), a common non-steroidal anti-inflammatory drug (NSAID) used to relieve pain and inflammation, exerts its effects through non-selective cyclooxygenase (COX) inhibition. Our lab has identified that the cyclooxygenase (COX-1 and COX-2) isoenzymes are expressed during the early stages of vertebrate embryonic development, and that global inhibition of COX-1 and COX-2 function disrupts NC cell migration and differentiation in Ambystoma mexicanum (axolotl) embryos. NC cells differentiate into various adult tissues including craniofacial cartilage, bone, and neurons in the peripheral and enteric nervous systems. To investigate the specific phenotypic and molecular effects of NPX exposure on NC development and differentiation, and to identify molecular links between COX inhibition and NC derivative anomalies, we exposed late neurula and early tailbud stage axolotl embryos to various concentrations of NPX and performed immunohistochemistry (IHC) for markers of migratory and differentiating NC cells. Our results reveal that NPX exposure impairs the migration of SOX9+ NC cells, leading to abnormal development of craniofacial cartilage structures, including Meckel's cartilage in the jaw. NPX exposure also alters the expression of markers associated with peripheral and central nervous system (PNS and CNS) development, suggesting concurrent neurodevelopmental changes.

A staging table of Balkan crested newt embryonic development to serve as a baseline in evolutionary developmental studies

There is an increased interest in the evolution and development of newts from the genus Triturus because: (1) morphological differentiation among the nine constituent species largely corresponds to different ecological preferences, (2) hybridization between different species pairs has various evolutionary outcomes in terms of life history traits and morphology, and (3) the genus expresses a balanced lethal system that causes arrested growth and death of half of the embryos. These features provide natural experimental settings for molecular, morphological, and life-history studies. Therefore, we produce a staging table for the Balkan crested newt (T. ivanbureschi). We provide detailed descriptions of 34 embryonic stages based on easily observable and interpretable external morphological characters, to ensure reproducibility. Compared with previous staging tables for Triturus, we include a vastly increased sample size and provide high-resolution photographs in lateral, ventral, and dorsal view, complemented by videos of specific developmental periods, and accompanied by detailed explanations on how to delineate the specific stages. Our staging table will serve as a baseline in comparative studies on Triturus newts: an emerging model system in evolutionary and developmental studies.