Mapping of ribosomal DNA and (TTAGGG)n telomeric sequence by FISH in the bivalve Patinopecten yessoensis (Jay, 1857)

Abstract

The chromosome set of Patinopecten yessoensis (Jay, 1857) was characterized using Giemsa staining, DAPI staining and fluorescence in situ hybridization (FISH) with three repetitive DNA probes [18S– 28S rDNA, 5S rDNA and telomeric (TTAGGG)n]. DAPI staining showed that AT-rich regions were located on the centromere of almost all chromosomes and interstitial banding was not observed. FISH showed that 18S– 28S rDNA spread over the short arms of two subtelocentric chromosome pairs and 5S rDNA was located on the long arm of one subtelocentric chromosome pair. Sequential FISH demonstrated that 18S– 28S and 5S rDNA were located on different chromosomes. FISH also showed that the vertebrate telomeric sequence (TTAGGG)n was located on both ends of each chromosome and no interstitial signals were detected. Sequential 18S– 28S rDNA and (TTAGGG)n FISH indicated that repeated units of the two multicopy families were closely associated on the same chromosome pair.