A radiolabelled pulse for the simultaneous study of anterograde and retrograde axonal transport

A technique is described for producing a pulse of [35S]methionine-labelled material which is axonally transported in amphibian sciatic nerve maintained in vitro. Using a position-sensitive detector of ionizing radiation, it is possible to continuously observe the movement of the pulse in the anterograde direction and, following turnaround at a ligature, the movement of a fraction of the pulse in the retrograde direction. Two sources of contaminant activity, which would otherwise interfere with observation of the pulse, are discussed and shown to be avoidable.