Hori Sayaka, Mitani Shohei
Department of Biological Sciences, Nara Women's University, Kitauoya-Nishimachi, Nara, 630 - 8263, Japan.
Department of Physiology, Tokyo Women's Medical University School of Medicine, 8-1, Kawada-cho, Shinjuku-ku, Tokyo, 162 - 8666, Japan.
Zoological Lett. 2025 Apr 17;11(1):4. doi: 10.1186/s40851-025-00250-7.
The optimization of avoidance behaviors in response to stress is an instinctual life function universally present in animals. In many sexually dimorphic animals, males exhibit higher stress resistance than females, but there have been no reports of comparative studies on stress resistance in sexually dimorphic hermaphrodites capable of reproducing alone. In the present study, we aimed to utilize a reversal/turn behavioral choice to conduct a comparative analysis of optimized avoidance behavior patterns in hermaphrodite and male Caenorhabditis elegans. We found that C. elegans males showed greater resistance to physical movement under acute stress and to lifespan reduction under chronic stress than C. elegans hermaphrodites. Interestingly, males exhibited a stronger avoidance behavior pattern known as "turn" than did the hermaphrodites, even in response to mild acute stress stimuli, to which they responded as if they had been exposed to strong stimuli. Stress conditions can lead to unsuccessful mating in C. elegans, and exaggerated stress avoidance in males may have biological significance for successful mating. This sexual dimorphism in avoidance behavior optimization was attributed to neural circuits downstream of the AIB neurons, the center of turn behavior, suggesting the presence of a novel mechanism distinct from previously reported neural and molecular mechanisms of avoidance behavior optimization.
对应激做出反应的回避行为优化是动物普遍存在的一种本能生命功能。在许多两性异形的动物中，雄性比雌性表现出更高的抗应激能力，但对于能够独自繁殖的两性异形雌雄同体动物的抗应激能力，尚无比较研究的报道。在本研究中，我们旨在利用反转/转向行为选择，对雌雄同体和雄性秀丽隐杆线虫的优化回避行为模式进行比较分析。我们发现，与秀丽隐杆线虫雌雄同体相比，秀丽隐杆线虫雄性在急性应激下对身体移动的抵抗力更强，在慢性应激下对寿命缩短的抵抗力更强。有趣的是，即使是对轻度急性应激刺激，雄性也表现出比雌雄同体更强的被称为“转向”的回避行为模式，它们对这种刺激的反应就好像受到了强烈刺激一样。应激条件会导致秀丽隐杆线虫交配失败，而雄性过度的应激回避可能对成功交配有生物学意义。回避行为优化中的这种两性差异归因于转向行为中心AIB神经元下游的神经回路，这表明存在一种不同于先前报道的回避行为优化神经和分子机制的新机制。
