Intron as a source of genetic polymorphism for fish population genetics

摘要

By incorporating polymerase chain reaction (PCR), DNA-level assays on nuclear genome (nDNA) such as microsatellite detection are becoming conventional. Yet, polymorphism at PCR priming sites may result in differential amplification of alleles (Pemberton et al., 1995). Furthermore, designing species-specific primers may be costly. Intron-targeted PCR employing primers designed from the conservative exon sequences may be an alternative candidate, because intron may accumulate much higher genetic variation than exons and polymorphism at priming sites is likely to be very rate. Quantity of fish genome data deposited to GenBank is much less than that of higher vertebrates, and most of the data is of cDNA. However, exon-intron arrangement appears to be hihgly conserved, making determination of intron position in the cDNA data possible. GenBank data search was performed to find homologous genes from lower to higher vertebrates, within which conserved sequences in exon regions were determined to design semi-universal primers for amplifying homologous intron among fish species. Here, I present genetic polymorphism observed in intron regions of several genes, and using the variation population genetic survey was performed in the swordfish (Xiphias gladius) and some tuna (Thunnus spp.) species.