Figure 1.

A pure preparation of isolated Aplysia sensory neurons as the starting material for cDNA library synthesis. Aplysia sensory cells were cultured for 5 d (A), and the cell bodies and ∼50 μm of the proximal axon segment were transected from the distal neurites using a sharp electrode (B). The cell bodies-proximal axon segments were then removed by aspiration, leaving a preparation of pure sensory neurites (C). Isolated sensory neurites were free of glia, as shown by propidium iodide (red) staining of sensory cell cultures before (D) and after (E) removal of cell bodies, which shows that there is no DNA left after removal of the sensory cell somata. Total RNA was prepared from sensory cell neurites and used to prepare cDNA by RT-PCR. The amplified cDNA was shown to contain mRNAs of neuritic but not glial origin by Southern blotting using a probe encoding sensorin, an mRNA known to be present in sensory cell processes, and a probe encoding a glial antigen (ag). Scale bar, 100 μm.