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

Abstract
Ribosomal genes have been localized on mitotic and lampbrush chromosomes of 20 specimens of Triturus vulgaris meridionalis by in situ hybridization with 3H 18S+28S rRNA. The results may be summarized as follows: 1) each individual shows positive in situ hybridization at the nucleolus organizing region (NOR) on chromosome XI; 2) in addition, many specimens exhibit a positive reaction in chromosomal sites other than the NOR (additional ribosomal sites); 3) the chromosomal distribution of the additional sites appears to be identical in different tissues from the same specimen and to follow a specific individual pattern; 4) the additional ribosomal sites are preferentially found at the telomeric, centromeric or C-band regions of the chromosomes involved.