Gallardo-Escárate, C., Á lvarez-Borrego, J., Del Río-Portilla, M. A., Cross, I., Merlo, A. and Rebordinos, L. 2005. Fluorescence in situ hybridization of rDNA, telomeric (TTAGGG) n and (GATA) n repeats in the red abalone Haliotis rufescens (Archaeogastropoda: Haliotidae). The physical location of 18S-5.8S-28S rDNA, telomeric sequences with (TTAGGG) n DNA probe and (GATA) n microsatellites were performed by fluorescence in situ hybridization in chromosomes of red abalone Haliotis rufescens. The

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... aryotype of red abalone showed a diploid number of 36 (8M'/9SM'/1ST). FISH performed with rDNA probe, showed the location of major ribosomal clusters in the terminal region of the large arms of two submetacentric pairs (chromosome 4 and 5). Localization of heteromorphisms of FISH-rDNA was found between chromosome homologues and sister chromatids in all metaphases analyzed. This indicates that rDNA clusters are variable within the red abalone genome. The variability in the NOR-bearing reported using silver staining in other gastropods and our result are discussed. In addition, the presence of microsatellite (TTAGGG) n and (GATA) n was demonstrated after FISH treatment by DNA probes. The telomeric sequence occurred at the ends of all mitotic chromosomes, while the (GATA) n repetitive was found on chromosomal interstitial zones as well as at the telomeres in abalone chromosomes.