Fig. 4.

A uniquely identified neuron (the CGC) coexpresses functional NOS mRNA and pseudo-NOS RNA. InA, the results of RT-PCR experiments on RNA purified from isolated identified CGCs are illustrated. Lane 4shows that a PCR product of the expected size (598 bp) is generated by primers specific to nNOS mRNA. Similarly, in lane 2, a PCR product of the expected size (431 bp) generated from the same RNA sample by primers specific to the pseudo-NOS RNA is detected.Lanes 1 and 3 show the results of PCR experiments designed to control for possible DNA contamination of the samples analyzed in lanes 2 and 4, respectively. In these experiments, reverse transcriptase was omitted, and as a consequence, no products were generated. InB, the results from isolated B2 motoneurons are presented. Lane 4 shows a PCR product of the expected size (598 bp) generated by the same nNOS-specific primers as used inA. Note that there is no PCR product in lane 2 in which the pseudo-NOS RNA-specific primers were used.Lanes 1 and 3 represent control experiments in which reverse transcriptase was omitted. The absence of any PCR products in these lanes proves that the RNA sample used in the RT-PCR experiments was free from DNA contamination. All RT-PCR products shown have been cloned and sequenced to confirm their identity.