Chromosomal studies in four species of genus Chaunus (Bufonidae, Anura): localization of telomeric and ribosomal sequences after fluorescence insitu hybridization (FISH)

Fluorescence insitu hybridization (FISH) using telomeric and ribosomal sequences was performed in four species of toad genus Chaunus: C. ictericus, C. jimi, C. rubescens and C. schneideri. Analyses based on conventional, C-banding and Ag-NOR staining were also carried out. The four species present a...

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Bibliographic Details
Published in:Genetica 2008-10, Vol.134 (2), p.159-168
Main Authors: Amaro-Ghilardi, Renata Cecilia, Silva, Maria Jose de Jesus, Rodrigues, Miguel Trefaut, Yonenaga-Yassuda, Yatiyo
Format: Article
Language:English
Subjects:
Amphibia
Anura
Bufonidae
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Summary:Fluorescence insitu hybridization (FISH) using telomeric and ribosomal sequences was performed in four species of toad genus Chaunus: C. ictericus, C. jimi, C. rubescens and C. schneideri. Analyses based on conventional, C-banding and Ag-NOR staining were also carried out. The four species present a 2n=22 karyotype, composed by metacentric and submetacentric chromosomes, which were indistinguishable either after conventional staining or banding techniques. Constitutive heterochromatin was predominantly located at pericentromeric regions, and telomeric sequences (TTAGGG) sub(n) were restricted to the end of all chromosomes. Silver staining revealed Ag-NORs located at the short arm of pair 7, and heteromorphism in size of NOR signals was also observed. By contrast, FISH with ribosomal probes clearly demonstrated absence of any heteromorphism in size of rDNA sequences, suggesting that the difference observed after Ag-staining should be attributed to differences in chromosomal condensation and/or gene activity rather than to the number of ribosomal cistrons.
ISSN:0016-6707
1573-6857
DOI:10.1007/s10709-007-9218-6