KARYOTYPE ANALYSIS AND CHROMOSOMAL LOCALIZATION BY FISH OF RIBOSOMAL DNA, TELOMERIC (H. CORRUGATA (ARCHEOGASTROPODA: HALIOTIDAE)

Abstract

The chromosomes of the blue abalone Haliotis fulgens and the yellow abalone Haliotis corrugata were analyzed by means of DAPI staining, and fluorescence in situ hybridization with 18S-5.8S-28S rDNA, telomeric (TTAGGG)n and (GATA)n repeats DNA probes. The diploid chromosome number found was 36 for both California abalone species. However, the karyologic comparison between H. fulgens and H. corrugata indicated that the blue abalone has 8M 8SM 2ST, whereas the yellow abalone has 10M 7SM 1ST. The physical location of 18S-5.8S-28S rDNA clusters was found in the terminal region of the long arms of two pairs of submetacentric chromosomes (4, 11 and 2, 4 respectively). Localization of heteromorphisms of FISH-rDNA between homologue chromosomes and between sister chromatids, and the presence of interstitial hybridization signals was found in metacentric and onto submetacentric chromosomes. The presence of microsatellites (TTAGGG)n and (GATA)n was evidenced after FISH treatment by DNA probes. The telomeric sequence occurred at the ends of all mitotic chromosomes in both abalone species, whereas the (GATA)n repetitive sequence was found on chromosomal interstitials zones and at the ends of some chromosomes, this was manifested after FISH on interphase nucleus. In addition, this study contributes with new karyologic information of haliotids from California and gives support to the Tethys model about biogeographical origin, from the Mediterranean Sea to the East Pacific Ocean.