Movie S6.

Proliferation of +1/2 defects during disruption of the aligned active nematic. Tracking of +1/2 defects during three consecutive disruptions of the laminar flow state. The experiment is performed with an ATP concentration of 140 μM. Velocity oscillations are accompanied with the periodic onset of defect proliferation. Because shear stress is much higher in this direction, transversally moving defects are more densely packed and advance more slowly than those along the laminar flow lanes.