RT Journal Article SR Electronic T1 Investigating the correlation of muscle function tests and sarcomere organization in C. elegans JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.04.13.439723 DO 10.1101/2021.04.13.439723 A1 Leila Lesanpezeshki A1 Hiroshi Qadota A1 Masoud Norouzi Darabad A1 Karishma Kashyap A1 Carla M. R. Lacerda A1 Nathaniel J. Szewczyk A1 Guy M. Benian A1 Siva A. Vanapalli YR 2021 UL http://biorxiv.org/content/early/2021/04/14/2021.04.13.439723.abstract AB Background Caenorhabditis elegans has been widely used as a model to study muscle structure and function due to many genes having human homologs. Its body wall muscle is functionally and structurally similar to vertebrate skeletal muscle with conserved molecular pathways contributing to sarcomere structure, and muscle function. However, a systematic investigation of the relationship between muscle force and sarcomere organization is lacking. Here, we investigate the contribution of various sarcomere proteins and membrane attachment components to muscle structure and function to introduce C. elegans as a model organism to study the genetic basis of muscle strength.Methods We employ two recently developed assays that involve exertion of muscle forces to investigate the correlation of muscle function to sarcomere organization. We utilized a microfluidic pillar-based platform called NemaFlex that quantifies the maximum exertable force and a burrowing assay that challenges the animals to move in three dimensions under a chemical stimulus. We selected 20 mutants with known defects in various substructures of sarcomeres and compared the physiological function of muscle proteins required for force generation and transmission. We also characterized the degree of sarcomere disorganization using immunostaining approaches.Results We find that mutants with genetic defects in thin filaments, thick filaments and M-lines are generally weaker, and our assays are successful in detecting the functional changes in response to each sarcomere location tested. We find that the NemaFlex and burrowing assays are functionally distinct informing on different aspects of muscle physiology. Specifically, the burrowing assay has a larger bandwidth in phenotyping muscle mutants, because it could pick ten additional mutants impaired while exerting normal muscle force in NemaFlex. This enabled us to combine their readouts to develop an integrated muscle function score that was found to correlate with the score for muscle structure disorganization.Conclusions Our results highlight the suitability of NemaFlex and burrowing assays for evaluating muscle physiology of C. elegans. Using these approaches, we discuss the importance of the studied sarcomere proteins for muscle function and structure. The scoring methodology we have developed lays the foundation for investigating the contribution of conserved sarcomere proteins and membrane attachment components to human muscle function and strength.Competing Interest StatementS. A. V. is the co-founder of NemaLife Inc. that commercializes C. elegans assays. The remaining authors declare that they have no competing interests.