ABSTRACT Many critical cellular processes, including cell proliferation and tissue repair, exhibit melatonin sensitivity. We examined the effects of exogenous melatonin, photoperiod and temperature on regeneration in Phagocata gracilis, a common North American turbellarian. Planarian regeneration involves the proliferation and migration of pluripotent stem cells capable of replacing missing body components. A characteristic mass of cells (blastema) forms during planarian regeneration, and its formation, growth and differentiation provide reliable endpoints for the study of regenerative processes. We tested the effects of exogenous melatonin at two concentrations and three photoperiods on both head and tail regenerates under seasonal diurnal temperature regimes. High temperatures and melatonin treatment increased mortality in P. gracilis, and surviving melatonin-treated subjects exhibited delayed regeneration. Asymmetrical and deficient regeneration was more common in melatonin-treated, high temperature and dark treated subjects. Additionally, high temperature and melatonin induced a novel locomotor dysfunction.

中文翻译：

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褪黑激素、光和温度对涡虫 Phagocata gracilis 再生的剂量依赖性破坏作用

摘要 许多关键的细胞过程，包括细胞增殖和组织修复，都表现出对褪黑激素的敏感性。我们研究了外源性褪黑激素、光周期和温度对北美常见涡虫 Phagocata gracilis 再生的影响。涡虫再生涉及能够替代缺失的身体成分的多能干细胞的增殖和迁移。涡虫再生过程中形成了特征性的细胞团（胚泡），其形成、生长和分化为再生过程的研究提供了可靠的终点。我们测试了两种浓度和三种光周期的外源性褪黑激素在季节性昼夜温度范围内对头部和尾部再生的影响。高温和褪黑激素处理增加了 P. gracilis 的死亡率，和幸存的褪黑激素治疗受试者表现出延迟再生。不对称和缺陷再生在褪黑激素治疗、高温和黑暗治疗的受试者中更为常见。此外，高温和褪黑激素诱发了一种新的运动功能障碍。