Genetic aspects of polymorphic C-bands in the chromosomes of the black rat (Rattus rattus tanezumi) in Japan.

Involving pericentric inversion, Robertsonian fusion and B-chromosomes , the black rat, Rattus rattus, is highly polymorphic. The polymorphism is also remarka ble by a variation of heterochromatic C-bands. R. rattus tanezumi, which is one of several subspecies of the black rats and distributes through Japan, is outstanding by polymorphism for the presence or absence of the C-bands (Yosida and Sagai 1975). Genetic analysis of the C-band polymorphism in man has been carried out by Craig-Holmes et al. (1973, 1975), Gimelli et al. (1976), Carnevale et al. (1976), Nakagome et al. (1977) and Hoehn et al. (1977). New variants of the bands have been known to occur in their offspring by Craig-Holmes et al., Gimelli et al . and Nakagome et al., while consistent inheritance of such bands has been reported by some others. In the mouse Forejt (1973) and Dev et al. (1975) indicated that the characteristic bands were regularly inherited in the offspring. The present article deals with a cytogenetic investigation of C-band poly morphism in the Japanese black rat, with special concern to the genetic analysis of the polymorphic C-bands.