Light-modulated neural control of sphincter regulation in the evolution of through-gut

    This article focuses on the evolution of the through-gut in bilaterians, specifically exploring the regulatory mechanisms that control sphincter function in sea urchin larvae. The authors demonstrate that light exposure influences the opening and closing of both the pyloric and anal sphincters, revealing a complex interplay of neural pathways and neurotransmitters. Blue light activates the Opsin3.2/serotonin pathway, leading to the opening of the pylorus, while longer wavelengths activate the Opsin2/ACh pathway, resulting in the opening of the anus. The study also suggests that dopamine neurons contribute to the regulation of both sphincters, with dopamine inhibiting anal opening and facilitating pyloric opening. The authors propose that this light-modulated sphincter regulation is a conserved feature of early deuterostomes and may have played a crucial role in the evolution of efficient nutrient absorption systems in bilaterians. Finally, the article discusses the potential implications of these findings for understanding digestive disorders and developing new livestock feeding strategies