The first chromosomal characteristics of nucleolar organizer regions (NORs) in grey featherback fish, notopterus notopterus (osteoglossiformes, notopteridae) by conventional and Ag-NOR staining techniques

Abstract

The first chromosomal characteristic of nucleolar organizer regions (NORs) and karyological analysis of the grey featherback fish {Notopterus notopterus) from Chi basin, northeast Thailand, were studied. Kidney cell samples were taken from 4 male and 4 female fish. The mitotic chromosome preparations were done directly from kidney cells. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of N. notopterus was 2n=42, the fundamental number (NF) was 42 in both males and females. The types of chromosomes were 8 large telocentric, 12 medium telocentric and 22 small telocentric chromosomes. The secondary constriction (NORs) was observed at the region adjacent to the centromere of the long arms of a pair of telocentric chromosome. The karyotype formula for N. notopterus is as follows: 2n (diploid)42 = L t8+ M t12+ S t22. © 2012 The Japan Mendel Society.