Muscle strength is a functional measure of quality of life in humans. Declines in muscle strength are manifested in diseases as well as during inactivity, aging, and space travel. With conserved muscle biology, the simple genetic model C. elegans is a high throughput platform in which to identify molecular mechanisms causing muscle strength loss and to develop interventions based on diet, exercise, and drugs. In the clinic, standardized strength measures are essential to quantitate changes in patients; however, analogous standards have not been recapitulated in the C. elegans model since force generation fluctuates based on animal behavior and locomotion. Here, we report a microfluidics-based system for strength measurement that we call ‘NemaFlex’, based on pillar deflection as the nematode crawls through a forest of pillars. We have optimized the micropillar forest design and identified robust measurement conditions that yield a measure of strength that is independent of behavior and gait. Validation studies using a muscle contracting agent and mutants confirm that NemaFlex can reliably score muscular strength in C. elegans. Additionally, we report a scaling factor to account for animal size that is consistent with a biomechanics model and enables comparative strength studies of mutants. Taken together, our findings anchor NemaFlex for applications in genetic and drug screens, for defining molecular and cellular circuits of neuromuscular function, and for dissection of degenerative processes in disuse, aging, and disease.

中文翻译：

---

NemaFlex：一种基于微流体的技术，用于线虫肌肉强度的标准化测量†

肌肉力量是人类生活质量的一项功能指标。肌肉力量的下降在疾病以及不活动，衰老和太空旅行中均表现出来。凭借保守的肌肉生物学，简单的遗传模型秀丽隐杆线虫是一个高通量平台，可在其中识别引起肌肉力量损失的分子机制，并根据饮食，运动和药物制定干预措施。在诊所中，标准化的强度测量对于量化患者的变化至关重要。然而，秀丽隐杆线虫尚未概括类似的标准因为力的产生是基于动物行为和运动而波动的，所以该模型是有效的。在这里，我们报告了一种基于微流体的强度测量系统，我们将其称为“ NemaFlex”，该系统基于线虫爬过柱林时的柱偏转。我们优化了微柱林的设计，并确定了可靠的测量条件，这些条件可得出与行为和步态无关的强度测量值。使用肌肉收缩剂和突变体的验证研究证实，NemaFlex可以可靠地对秀丽隐杆线虫的肌肉强度进行评分。此外，我们报告了一个比例因子来解释与生物力学模型相符的动物体型，并能够进行突变体的比较强度研究。综上，我们的发现锚定NemaFlex在遗传和药物筛选中的应用，用于定义神经肌肉功能的分子和细胞回路，以及解剖废旧，衰老和疾病中的退化过程。