Species that depend on membership in social groups for survival exhibit changes in neuronal gene expression and behaviour when they face restricted social interactions or isolation 1 – 3 . Here we show that, across the lifespan of zebrafish ( Danio rerio ), social isolation specifically decreased the level of transcription of pth2 , the gene that encodes the vertebrate-specific neuropeptide Pth2. However, 30 minutes of exposure to conspecifics was sufficient to initiate a significant rescue of pth2 transcript levels in previously isolated zebrafish. Transcription of pth2 exhibited bidirectional dynamics; following the acute isolation of socially reared fish, a rapid reduction in the levels of pth2 was observed. The expression of pth2 tracked not only the presence of other fish but also the density of the group. The sensory modality that controls the expression of pth2 was neither visual nor chemosensory in origin but instead was mechanical, induced by the movements of neighbouring fish. Chemical ablation of the mechanosensitive neuromast cells within the lateral line of fish prevented the rescue of pth2 levels that was induced by the social environment. In addition, mechanical perturbation of the water at frequencies similar to the movements of the zebrafish tail was sufficient to rescue the levels of pth2 in previously isolated fish. These data indicate a previously underappreciated role for the relatively unexplored neuropeptide Pth2 in both tracking and responding to the population density of the social environment of an animal. In zebrafish, the expression levels of the neuropeptide Pth2 change as exposure to conspecifics is limited or increased, and these changes track the presence of individuals and group density through mechanical stimulations induced by the movements of other fish.

中文翻译：

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神经肽 Pth2 通过机械感觉动态感知他人

依赖社会群体成员生存的物种在面临有限的社会互动或孤立时会表现出神经元基因表达和行为的变化 1 - 3。在这里，我们表明，在斑马鱼 ( Danio rerio ) 的整个生命周期中，社会隔离特别降低了 pth2 的转录水平，pth2 是编码脊椎动物特异性神经肽 Pth2 的基因。然而，暴露于同种动物 30 分钟足以开始显着拯救先前分离的斑马鱼中的 pth2 转录水平。pth2 的转录表现出双向动力学；在社会饲养的鱼被严重隔离后，观察到 pth2 水平迅速下降。pth2 的表达不仅跟踪其他鱼的存在，还跟踪该组的密度。控制 pth2 表达的感觉方式在起源上既不是视觉也不是化学感觉，而是机械的，由邻近鱼的运动引起。对鱼侧线内的机械敏感神经肥大细胞进行化学消融阻止了由社会环境诱导的 pth2 水平的恢复。此外，以类似于斑马鱼尾巴运动的频率对水的机械扰动足以挽救先前分离的鱼中 pth2 的水平。这些数据表明，相对未开发的神经肽 Pth2 在跟踪和响应动物社会环境的人口密度方面的作用以前被低估了。在斑马鱼中，神经肽 Pth2 的表达水平随着暴露于同种物种的限制或增加而变化，