Identification and distribution of gynogenetic clones in silver crucian carp Carassius langsdorfii collected from the Dokanbori moats of the Imperial Palace, Tokyo, Japan

摘要

A total of 201 silver crucian carp Carassius langsdorfii were collected from the inner moats, Kami-dokanbori, Naka-dokanbori and Shimo-dokanbori of the Imperial Palace, Tokyo, Japan, in 1996, 1997 and 1998. These moats were constructed about 400 years ago and the Kami-dokanbori has been separated by a 10 m high causeway from the other moats for at least 100 years. Ploidy determination by DNA content measurements using flow cytometry revealed that all the specimens examined were categorized to 196 triploids and 5 tetraploids. All the triploids sexchecked (n=136) were female except for 6 immature individuals. All tetraploids examined (n-5) were female. Multilocus DNA fingerprinting identified 7 clonal lines (clone I-VII) based on the genetic identity between at least two samples. Individual specific DNA fingerprints were detected in eight specimens, suggesting the presence of 8 or more independent clonal lines. Among the 7 clones, clone I was the most predominant in the three Dokanbori moats, but the frequency was different among the samples examined in each year. Clone I and VI in the Imperial Palace were genetically identical to clone 8 and 6 detected in the Chugoku district, respectively. High genetic similarities between clone I triploid and four tetraploid individuals shown by DNA fingerprinting analysis suggest that these tetraploids may be produced by accidental incorporation of haploid sperm genome into gynogenetic triploid genotype.