Chromosomal characteristics of ribosomal DNA in the primitive semionotiform fish, longnose gar Lepisosteus osseus

P. Ráb, M. Rábová, K. M. Reed, R. B. Phillips

Research output: Contribution to journalArticle

30 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)475-480
Number of pages6
JournalChromosome Research
Volume7
Issue number6
DOIs
StatePublished - Nov 6 1999

Keywords

  • Chromomycin A-banding
  • FISH
  • Fish cytogenetics
  • GC-rich heterochromatin
  • Longnose gar

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