Disruption of <i>mc1r</i> Disturbs Skin Pigmentation in <i>Xenopus tropicalis</i>

The melanocortin 1 receptor (MC1R) is well-established as a pivotal regulator of pigmentation in various species. Despite a wealth of research focused on mammals and fish, the role of Mc1r in amphibians has remained largely unexplored. This study was designed to elucidate the contribution of Mc1r in Xenopus tropicalis. Our results reveal that targeted ablation of mc1r in Xenopus tropicalis led to a significant reduction in dorsal skin pigmentation, while simultaneously accelerating the onset of melanophore pigmentation in the ventral region. This dual effect resulted in a perturbation of the canonical countershading pattern. Additionally, knockout of mc1r disrupted the expression of multiple genes primarily associated with pigmentation. Collectively, these findings underscore the critical role of MC1R in the regulation of pigmentation and the development of countershading in amphibians, contributing to the growing body of literature on the evolution and function of MC1R across vertebrate species.