Fig. 3

Muscle shortening in acc and wild type fish. Lateral view of a few segments in the intact tail of (A) wild type and (B) acc fish. Top is dorsal. Arrows point to individual muscle cells. (C) Muscle displacement over time in the intact tail of a 9-day wild type (blue, triangles) and acc (red, circles) fish in response to a train of six 1-ms current pulses applied to muscle. High-speed images of stimulus-induced muscle contraction and relaxation were taken every 1 ms. From these images, measurements of muscle displacement were made by tracking, frame by frame, the movement of a single point on an individual muscle cell, using Photron Motion Tools software. The magnitude of the response was then normalized to the maximum displacement observed and plotted as a function of time. Arrowheads indicate the time of stimulation.