Abstract
The control region of mitochondrial DNA, known to be the most variable in the genome, was analyzed so as to assess its suitability for examining genetic variability and population structure in the Japanese flounder. A total of 424 nucleotide sites, including the proline transfer RNA gene and the first half of the control region, was sequenced from 55 specimens from Niigata, Honshuand Sado Island, off the north-western coast of Honshu. Out of 350 nucleotide sites on the control region, 126 (36.0%) were variable, 54 haplotypes being found. Differences between nucleotide sequences ranged between 0 and 8.3% with an average (=nucleotide diversity) of 4.33%, indicating that the control region of the mitochondrial DNA in the Japanese flounder is characterized by extremely high variability. The frequency in occurrence of specific nucleotides in 2 sites in the Niigata sample differed significantly from that in the Sado Island sample. This result accorded with previous studies which suggested Japanese flounder populations in Niigata and Sado belong to different local populations.
