Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
Lab Chip. 2018 Jul 24;18(15):2187-2201. doi: 10.1039/c8lc00103k.
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.
肌肉力量是人类生活质量的一个功能性衡量标准。肌肉力量的下降表现在疾病、缺乏运动、衰老和太空旅行中。由于肌肉生物学是保守的，简单的遗传模型秀丽隐杆线虫是一个高通量的平台，可以用来识别导致肌肉力量丧失的分子机制，并基于饮食、运动和药物来开发干预措施。在临床上，标准化的力量测量对于定量评估患者的变化至关重要；然而，由于力量产生取决于动物的行为和运动，类似的标准在秀丽隐杆线虫模型中尚未被重现。在这里，我们报告了一种基于微流控的力量测量系统，我们称之为“NemaFlex”，它基于线虫在一片柱子森林中爬行时的柱子挠度。我们已经优化了微柱林的设计，并确定了稳健的测量条件，得出了一种与行为和步态无关的力量测量值。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力量进行评分。此外，我们还报告了一个比例因子，用于考虑动物的大小，该比例因子与生物力学模型一致，可用于比较突变体的力量研究。总之，我们的研究结果为 NemaFlex 在遗传和药物筛选、神经肌肉功能的分子和细胞回路的定义以及对废用、衰老和疾病中退行性过程的剖析中的应用奠定了基础。
