Karyotype analysis of Fringilla coelebs (Aves, Passeriformes) using fluorochrome staining, Ag-NOR and FISHSvetlana Derjusheva, Anna Kurganova, Alsu Saifitdinova and Elena Gaginskaya
Biological Institute of Saint-Petersburg University, Saint-Petersburg, 198504 RUSSIA
|Chromosome complements of various passerine species are similar in the chromosome numbers and morphology. On the other hand, a deep divergence between Passeriformes and other birds manifests itself in chromosomal rearrangements. Fringilla coelebs, widely distributed in the world species, is a typical representative of the order Passeriformes. So the chaffinch may serve as a model species to study the origin, evolution and structural organization of passerine chromosomes.|
The karyotype of F.coelebs (2n=80) consists of 7 pairs of biarmed macrochromosomes: 6 autosome pairs, Z and W. The rest chromosomes are microchromosomes. Three pairs of largest microchromosomes are easily determined and acrocentric.
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Metaphase chromosomes obtained from fibroblast culture are stained by Chromomycin A3 (CMA3) and DAPI simultaneously. Centromeric heterochromatin of each chromosome was found to be GC-enriched (green). Euchromatin arms of macrochromosomes are generally CMA-negative (blue). As to microchromosomes, they are either GC-enriched or AT-enriched.
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R-banded macrochromosome idiograms created accordingly with computer measument of CMA-stained metaphase spreads.
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rRNA loci are localized on a pair of miccrochromosomes (arrows) by FISH with Xenopus 18S+28S rDNA probe. FITC/PI
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Ag-staining also revealed a pair of NOR-bearing chromosomes (arrows).
The results demonstrate that in Fringilla coelebs chromosome set the NOR location is typical of bird karyotype.
The localization of (TTAGGG)n in chaffinch chromosomes
It is well known that in addition to terminal sites of (TTAGGG)n telomeric repeat there are chromosome interstitial sites of that, their origin being a subject of discussion (Meyne et al., 1990; Nanda & Schmid, 1994). Comparative analysis of TTAGGG sites distribution may provide understanding of chromosomal reorganization during karyotype evolution.
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FISH on chaffinch metaphase chromosomes using human telomeric repeat as a probe. Cy3/ CMA3.
In the chaffinch interstitial (TTAGGG)n sites are revealed on all macrochromosomes.
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Selected macrochromosomes 1 to 6 and ZW sex chromosomes of the chaffinch after FISH with (TTAGGG)n probe. On the left - CMA3; on the right - Cy3/CMA3.
It is worthy to remark that in total the chaffinch chromosomes contain more interstitial TTAGGG sites revealed by FISH as compared with species from other avian orders, most of the interstitial sites being out of pericentromeric regions. It may reflect the evolutionary status of Passeriformes.
The karyotype of the chaffinch was previously described by Piccini & Stella (1970), but only in routine staining. Here, fluorescent chromosome banding, NOR detection by FISH and Ag-staining, and the distribution of telomeric TTAGGG repeat in metaphase chromosomes are presented for the first time.
Meyne J. et al. (1990) Chromosoma 99: 310.