Optogenetics allows the experimental manipulation of excitable cells by a light stimulus without the need for technically challenging and invasive procedures. The high degree of spatial, temporal, and intensity control that can be achieved with a light stimulus, combined with cell type-specific expression of light-sensitive ion channels, enables highly specific and precise stimulation of excitable cells. Optogenetic tools have therefore revolutionized the study of neuronal circuits in a number of models, including Caenorhabditis elegans. Despite the existence of several optogenetic systems that allow spatial and temporal photoactivation of light-sensitive actuators in C. elegans, their high costs and low flexibility have limited wide access to optogenetics. Here, we developed an inexpensive, easy-to-build, modular, and adjustable optogenetics device for use on different microscopes and worm trackers, which we called the OptoArm. The OptoArm allows for single- and multiple-worm illumination and is adaptable in terms of light intensity, lighting profiles, and light color. We demonstrate OptoArm’s power in a population-based multi-parameter study on the contributions of motor circuit cells to age-related motility decline. We found that individual components of the neuromuscular system display different rates of age-dependent deterioration. The functional decline of cholinergic neurons mirrors motor decline, while GABAergic neurons and muscle cells are relatively age-resilient, suggesting that rate-limiting cells exist and determine neuronal circuit ageing. We have assembled an economical, reliable, and highly adaptable optogenetics system which can be deployed to address diverse biological questions. We provide a detailed description of the construction as well as technical and biological validation of our set-up. Importantly, use of the OptoArm is not limited to C. elegans and may benefit studies in multiple model organisms, making optogenetics more accessible to the broader research community.

中文翻译：

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一种经济且适应性强的光遗传学系统，用于对秀丽隐杆线虫进行个体和群体水平的操作

光遗传学允许通过光刺激对可兴奋细胞进行实验性操作，而无需技术上具有挑战性和侵入性的程序。通过光刺激可以实现高度的空间、时间和强度控制，结合光敏离子通道的细胞类型特异性表达，可以对可兴奋细胞进行高度特异性和精确的刺激。因此，光遗传学工具彻底改变了许多模型中神经元回路的研究，包括秀丽隐杆线虫。尽管存在几种允许线虫中光敏致动器的空间和时间光激活的光遗传学系统，但它们的高成本和低灵活性限制了光遗传学的广泛应用。在这里，我们开发了一种廉价、易于构建、模块化、和可调节的光遗传学设备，用于不同的显微镜和蠕虫追踪器，我们称之为 OptoArm。OptoArm 允许单个和多个蠕虫照明，并且在光强度、照明配置文件和光色方面具有适应性。我们在一项基于人群的多参数研究中展示了 OptoArm 的能力，该研究涉及运动电路细胞对与年龄相关的运动能力下降的贡献。我们发现神经肌肉系统的各个组成部分显示出不同的年龄依赖性恶化率。胆碱能神经元的功能衰退反映了运动衰退，而 GABA 能神经元和肌肉细胞具有相对的年龄弹性，这表明限速细胞的存在并决定了神经元回路的老化。我们组装了一个经济、可靠、和高度适应性的光遗传学系统，可用于解决各种生物学问题。我们提供了结构的详细描述以及我们设置的技术和生物学验证。重要的是，OptoArm 的使用不仅限于秀丽隐杆线虫，还可能有益于对多种模式生物的研究，从而使更广泛的研究界更容易获得光遗传学。