ISSN:
1573-6849
Keywords:
chromomycin A3-banding
;
FISH
;
fish cytogenetics
;
GC- rich heterochromatin
;
longnose gar
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The chromosomes of longnose gar, Lepisosteus osseus, an extant representative of early radiation of actinopterygian fishes, were studied using conventional Giemsa-staining, Ag-staining, CMA3-fluorescence and fluorescence in-situ hybridization (FISH). The diploid chromosome number was 2n = 56 and the karyotype contained 11 pairs of metacentric, 6 pairs of submetacentric, 3 pairs of subtelocentric macrochromosomes and 16 microchromosomes. Nearly all macrochromosomes showed large CMA3-positive regions resembling the R-bands of higher vertebrates, indicating extensive distribution of GC-rich DNA along chromosomes. The nucleolar organizer regions (NORs) were located on the end of the short arm of a single small metacentric macrochromosomal pair. These sites were strongly CMA3-positive, suggesting that ribosomal sites are associated with GC- rich DNA. In-situ hybridization (FISH) with a rDNA probe gave consistently positive signals in the same regions detected by Ag- staining and CMA3-fluorescence. The evolutionary conservation of positive CMA3-fluorescence of ribosomal sites in ‘holostean’ and teleostean fishes is discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1009202030456
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