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Neuron tracing and quantitative analyses of dendritic architecture reveal symmetrical three-way-junctions and phenotypes of git-1 in C. elegans

Fig 3

The worm’s coordinate system and PVD feature extraction.

A. The coordinate system used to characterize the PVD neuron is defined by ; where is locally tangential to the worm’s longitudinal axis, points along the local dorsal direction, and points in the direction of the worm’s right. B. Using the projection image of the non-planar PVD neuron, an outline image is generated using morphological operations applied to the neuron’s trace. This is used to find the neuron’s centerline and borderline. C. A schematic of the worm’s cross section. The azimuthal angle ϕ denotes the azimuthal position of PVD elements. r, radius at each point; d, distance. D. A schematic of the worm from a left/right side view. The angle θ denotes the orientation of PVD elements, defined as the angle between the longitudinal axis, , and the local tangent, . E, F. Visualization of the azimuthal angle ϕ (E) and distribution of the PVD elements for different ϕ angles (F, n = 10). The peaks at 0 and ±35° correspond to the primary (red) and tertiary (green, dorsal are positive and ventral are negative values) branches. Same neuron as Fig 1A. G, H. Visualization (G) and distribution (H) of orientation angle, θ, for PVD elements (n = 10). The distribution shows that most of the neuron’s length is either parallel (red) or perpendicular (green) to the midline. D = dorsal, V = ventral, L = left, R = right, A = anterior, P = posterior.

doi: https://doi.org/10.1371/journal.pcbi.1009185.g003