Fig. 2. RT-PCR products generated using specific primers for acetylcholine receptor genes amplified from H. monopterigium. RNA isolated from the electric organ of the coffin ray was reverse transcribed and amplified using primers specific for either the , ß, or genes of the acetylcholine receptor. Two RNA concentrations were tested with each primer pair, and RT-PCR products were run on a 0.8% agarose gel and stained with ethidium bromide. Lambda DNA cut with EcoR1 and HindIII was used to estimate the size of the DNA fragments (left-hand lane).