Abstract
Distribution of B-chromosomes and the frequency of specimens with the Robertsonian fission are observed in 13 Japanese raccoon dogs collected in different localities. Among 13 specimens, 2 B's and 3 B's are observed in 5 specimens, respectively, and the remaining 4 specimens have 4 B's. The specimens without B's have not been observed so far. Among these animals, 5 specimens have the Robertsonian fission; three in no. 8, one in no. 6 and the remaining one in nos. 5, 8 and 11. The somatic variation of B's is analysed in 1, 372 cells in total obtained from the 13 specimens. Cells with 2, 3 and 4 B's are observed more frequently, while the cells with 1, 5, 6, and 7 B's are extremely fewer. The cells without the B's and with more than the 8 B's have not been observed. These investigations suggest that the Japanese raccoon dogs with few B-chromosomes are preferentially selected in the natural population of Japan.
