CHARACTERIZATION OF NUCLEOLAR ORGANIZER REGIONS OF 12 SPECIES OF CHINESE CYPRINID FISHES

Silver staining technique was used to study the chromosomal NORs of 12 species of Chinese cyprinids. The NOR number varies from 2 to 7. Only a single pair of NOR-bearing chromosomes was detected in 5 species re spectively. The remaining species each possess two or more pairs of NO R-bearing homologues. NORs may be located at submetacentric, subteloce ntric or metacentric chromosomes. NOR heteromorphism was common. Final ly, it is suggested, in the discussion, that further studies should be made on the overall Cyprinidae.