Amplification of PwRn1 transcripts. Reverse-transcription PCR (RT-PCR) was performed with the total RNAs extracted from diploid (Haenam, Hn) and triploid (Bogil-do, Bg) worms and PwRn1-specific primers. The RNAs were examined by conventional PCR to verify the absence of any contaminating genomic DNAs, prior to the RT-PCR (data not shown). The PCR products were analyzed by agarose gel-electrophoresis. A primer pair for the β-actin gene was used as a house-keeping gene control. M, 100-bp DNA ladder.