Chromosome location of the ribosomal RNA genes in Triturus vulgaris meridionalis (Amphibia, Urodela)

The mitotic chromosomes of six specimens from Triturus vulgaris meridionalis have been examined by both in situ hybridization with 3H 18S + 28S rRNA and AS-SAT staining method. The results of these two sets of experiments can be summarized as follows: 1) in each specimen the NORs and the additional ribosomal sites, which react positively to in situ hybridization with 3H 18S + 28S rRNA, are also stained by silver; 2) other chromosomal regions, which do not hybridize in situ with 3H 18S + 28S rRNA, are on the other hand stained by the AS-SAT method. These latter AG-positive sites show a species-specific pattern of chromosomal distribution.