ISSN:
1573-6849
Keywords:
fish
;
fluorescent CMA bands
;
in situ hybridization
;
NOR polymorphisms
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Silver nitrate staining, a rapid and efficient method, has proven to be excellent for nucleolar organizing region (NOR) studies in fish. Some fish appear to have only two NOR-bearing chromosomes in their karyo-type, whereas others probably have several. In the present study we analyzed the NORs ofLeporinus friderici, a species that, on the basis of previous studies, has been considered as representative of species with NORs carried by a single chromosome pair. The analyses were performed by a combination of three methods,i.e. silver nitrate staining, staining with the GC-specific fluorochrome chromomycin A3, andin situ hybridization with digoxigenin-labeled probes. The results showed that, although more frequent and conspicuous in a single chromosome pair, the NORs of this species are present in multiple chromosomes. Intra- and inter-individual variations observed by the three methods strongly suggest the occurrence of post-zygotic modifications involving NORs. NOR identification in fish, almost exclusively performed by the silver nitrate method, is currently being re-evaluated by methods such as chromomycin A3 staining andin situ hybridization, which may provide important information leading to a better understanding of chromosome evolution in these animals.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00713066
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