Chromosome Banding in Amphibia. XXXV. Highly Mobile Nucleolus Organizing Regions in Craugastor fitzingeri (Anura, Craugastoridae).

A 7-year cytogenetic study on the leaf litter frog Craugastor fitzingeri from Costa Rica and Panama revealed the existence of highly mobile nucleolus organizing regions (NORs) in their genomes. Silver (Ag)-staining of the active NORs demonstrated an exceptional interindividual pattern of NOR distribution at the telomeres of the chromosomes. All individuals examined showed a different and specific NOR location in their karyotypes.

Cytogenetic studies on Gonatodes (Reptilia, Squamata, Sphaerodactylidae).

Mitotic and meiotic chromosomes of 5 species of the reptile genus Gonatodes are described by means of conventional staining, banding analyses and in situ hybridization using a synthetic telomeric DNA probe. The amount, location and fluorochrome affinities of constitutive heterochromatin, the number and positions of nucleolus organizer regions, and the patterns of telomeric DNA sequences were determined for most of the species. The karyotypes of G.

Chromosome banding in Amphibia. XXXI. The neotropical anuran families Centrolenidae and Allophrynidae.

The mitotic chromosomes of 11 species from the anuran families Centrolenidae and Allophrynidae were analyzed by means of conventional staining, banding techniques, and in situ hybridization. The amount, location, and fluorochrome affinities of constitutive heterochromatin, the number and positions of nucleolus organizer regions, and the patterns of telomeric DNA sequences were determined for most of the species. The karyotypes were found to be highly conserved with a low diploid chromosome number of 2n = 20 and morphologically similar chromosomes.

Distribution of telomeric (TTAGGG)(n) sequences in avian chromosomes.

The physical ends of mammalian and other vertebrate chromosomes consist of tandemly repeated (TTAGGG)(n) hexamers, nucleating a specialized telomeric structure. However, (TTAGGG)(n) sequences can also occur at non-telomeric sites, providing important insights into karyotypic evolution. By fluorescence in situ hybridization (FISH) we studied the chromosomal distribution of (TTAGGG)(n) sequences in 16 bird species, representing seven different orders.