Differentially expressed genes between C.elegans with low physical ability and with high physical ability

Aging is an important risk factor for disease and is accompanied by the decline of many physiological characteristics, including physical performance. One of the most powerful tests of physical ability in elderly humans is the short physical performance battery (SPPB) (Guralnik et al., 1994), an assessment of the maximum exercise capacity of lower extremities over a short period of time. A similar metric of maximum velocity (MV) in a short period (30 s) is proposed as an equally informative measurement in C. elegans (Hahm et al., 2015). MV declines with age, correlates well with longevity, accurately reports movement ability, and importantly, is predictive of future longevity (Hahm et al., 2015). Here, we characterized the differences in gene expression between high MV group and low MV group of the same age in C. elegans. The genes related to nucleosomes and involved in regulatory processes, including transcriptional regulation (chromatin assembly, regulation of RNA metabolic process and regulation of transcription), and neuronal signaling (neurogenesis, axon guidance, and regulation of neurotransmitter levels) were up-regulated in low MV group compared to high MV group. In contrast, genes belonged to metabolic processes and mitochondria were down-regulated in low MV group compared to high MV group. We utilized maximum velocity (MV) assay (Hahm et al., 2015) to divide an aged population of C. elegans into groups of low and high physical ability. Worms grown in growth plates ad libitum (AL) were moved to a physical assay plate with no food on day 7-8 of adulthood to measure their MV. The locomotion of worm was recorded for 30 seconds using a stereomicroscope, a CCD camera. Recorded images were analyzed by ImageJ and wrMTrck (plugin for ImageJ: www.phage.dk/plugins). The peak locomotion velocity observed in the 30 second period was used as the MV. Worms with an MV of less than 0.22 mm/sec, which corresponds to the minimum MV at day 1 of adulthood, were regarded as low physical ability (Hahm et al., 2015), otherwise, regarded as high physical ability. The analysis was carried out with two replicates of each high MV and low MV groups.