DOI: 10.5061/dryad.stqjq2c8p
title: Data from: Dimensionality of locomotor behaviors in developing C. elegans

description: Adult animals display robust locomotion, yet the timeline and mechanisms
 of how juvenile animals acquire coordinated movements and how these
 movements evolve during development are not well understood. Recent
 advances in quantitative behavioral analyses have paved the way for
 investigating complex natural behaviors like locomotion. In this study, we
 tracked the swimming and crawling behaviors of the nematode Caenorhabditis
 elegans from postembryonic development through to adulthood. Our principal
 component analyses revealed that adult C. elegans swimming is low
 dimensional, suggesting that a small number of distinct postures, or
 eigenworms, account for most of the variance in the body shapes that
 constitute swimming behavior. Additionally, we found that crawling
 behavior in adult C. elegans is similarly low dimensional, corroborating
 previous studies. Further, our analysis revealed that swimming and
 crawling are distinguishable within the eigenworm space. Remarkably, young
 L1 larvae are capable of producing the postural shapes for swimming and
 crawling seen in adults, despite frequent instances of uncoordinated body
 movements. In contrast, late L1 larvae exhibit robust coordination of
 locomotion, while many neurons crucial for adult locomotion are still
 under development. In conclusion, this study establishes a comprehensive
 quantitative behavioral framework for understanding the neural basis of
 locomotor development, including distinct gaits such as swimming and
 crawling in C. elegans.
description: Preparation of Worms Wild type hermaphrodite
 <em>C. elegans</em> (N2 Bristol) worms from the CGC
 (Minneapolis, MN, USA) were used for all assays. The worms were maintained
 at 15°C on 60mm NGM agarose plates with Escherichia coli OP50 lawns as
 food. To obtain worms at later stages of development, synchronization
 procedures were carried out in which 20 gravid hermaphrodites were placed
 on seeded NGM plates. After one hour, all worms were subsequently removed,
 leaving only eggs on the plates which were immediately put into a 20°
 incubator. After 21 hours of incubator growth time for late L1s, 29 hours
 for L2s, 42 hours for L3s, 50 hours for L4s, and 65 hours for adult worms,
 the synchronized animals were subjected to assays. Young L1 recently
 hatched animals were collected by transferring 50 gravid hermaphrodites to
 a seeded plate 24 hours before the experimental assay. On the day of the
 experiment, the plate with gravid hermaphrodites and laid eggs was washed
 with M9 buffer until all animals and bacteria were removed leaving only
 eggs on the plate. Over the course of an hour, plates were closely
 monitored for hatching and newly hatched young L1 animals were subjected
 to assays. Assays  To obtain
 locomotion data across the stages of development, worms synchronized at
 each stage were subjected to swimming and crawling assays in which their
 movements were captured on video. All assays were conducted on NGM plates
 with no bacterial lawn. For crawling assays, worms were starved for one
 hour prior to the start of the assay. A platinum wire worm pick was used
 with Halocarbon 700 oil to transfer 20 worms onto a 90mm NGM plate in the
 absence of OP50. We took 1–2 minute-long video clips of each crawling
 worm. For swimming assays, each worm was transferred using a pick into a
 5, 10, or 15µl drop of M9 buffer solution placed on the surface of the
 assay plate for L1-L2, L3, and L4-adult animals, respectively. M9 droplets
 were flattened with a worm pick in a circular motion beforehand to reduce
 glare. For each assay, one minute was allowed for the worm to acclimate to
 swimming conditions before 1–2 minutes of the worm's locomotion was
 tracked and analyzed. For gait transition assays, we followed the crawling
 protocol for adult animals, however, we added a 1.5µl drop of M9 buffer to
 the plate in the worm’s path following previously reported
 protocols. Tracking WormLab
 imaging stations were used in conjunction with WormLab software (both from
 MBF Bioscience) to capture videos of the worms and subsequently track the
 curvature data of each worm. Additionally, for young and late L1 larval
 assays, a macro lens (LAOWA 25mm F2.8 2.5-5x ULTRA MACRO) at 2.5x
 magnification was mounted instead of the default lens in order to capture
 the small worms at high resolution. All videos were taken at 1200x1600
 resolution and 14 frames per second. To ensure worms remained in the field
 of view, assay plates were gently moved if necessary. For each worm, the
 angles between each of the eleven segments along the length of the animal
 (as defined by the WormLab software) were used to define the worm's
 curvature for each video frame. We segmented the animal into 5, 9, 11, 17,
 and 33 segments and found no significant differences in eigenworm shape
 analyses with more than 11 segments on a small held-out test data set.
 Subsequently, we proceeded with 11 segments (10 subsequent segment angles)
 for the remainder of the study.
description: # Data from: Dimensionality of locomotor behaviors in developing C.
 elegans ## Description of
 the data and file structure Data are organized into subfolders according
 to their locomotion type and developmental stage. Each .txt file contains
 tracking of a single worm with the first column showing timestamps and the
 next 10 columns showing the animal curvature in radians for that row.
 Files are named by date_strain_age_gait_file# or
 date_strain_age_gait_file#_worm# if there was more than one worm in a
 given assay. One adult swimming to crawling transition assay was included
 in this study for which there is one .txt file for.  ## Code/Software
 Custom written Python scripts to reproduce figures will be made publicly
 available at the time of publication.