Molecular and cytogenetic characterization of repetitive DNA in the Antarctic polyplacophoran Nuttallochiton mirandus Maria Assunta Biscotti 1 , Marco Barucca 1 , Teresa Capriglione 2 , Gaetano Odierna 3 , Ettore Olmo 1 & Adriana Canapa 1 * 1 Istituto di Biologia e Genetica, Facolta`di Scienze, Universita`Politecnica delle Marche, via Brecce Bianche, I-60131 Ancona, Italy; Tel: +39-071-2204619; Fax: +39-071-2204609; E-mail: a.canapa@univpm.it; 2 Dipartimento di Biologia Evolutiva e Comparata, Universita`di Napoli FFederico II_, via Mezzocannone 8, Napoli, Italy; 3 Dipartimento di Biologia Strutturale e Funzionale, Complesso Monte S. Angelo, Universita` di Napoli FFederico II_, via Cinthia, Napoli, Italy * Correspondence Received 19 December 2007. Resubmitted and accepted for publication by Herbert Macgregor 9 June 2008 Key words: chiton, fluorescence in-situ hybridization, Nuttallochiton mirandus, satellite DNA Abstract Two highly repeated DNAs, designated NmE1/NmE2 and NmE5, were identified by EcoRV digestion in the chiton Nuttallochiton mirandus (Mollusca: Polyplacophora). The comparison of the sequences obtained showed high similarity in 5¶ and 3¶ regions and the NmE5 sequence displayed an inserted sequence that might arise from a transposable element. Southern blotting analyses suggested a tandem organization of both satellite DNA families identified. Moreover, dot blot analyses, performed on several molluscan species, revealed a different degree of conservation of the repeated DNAs. Fluorescence in-situ hybridizations (FISH) on metaphase chromosomes showed that both satellite DNAs are located at centromeric regions. Introduction Comparative studies of satellite DNA sequences are numerous in vertebrates but less common in inver- trebrates. In molluscs in particular, the possible presence and characteristics of satellite sequences have been investigated only in the Bivalvia and Gastropoda classes (Ruiz-Lara et al. 1992, Clabby et al. 1996, Plohl & Cornudella 1996, 1997, Muchmore et al. 1998, Martı ´nez-Lage et al. 2002, 2005, Lo ´pez-Flores et al. 2004, Petrovic ´ & Plohl 2005, Biscotti et al. 2007). This work analyses for the first time satellite DNA in the Polyplacophora class and characterizes two families of highly repeated DNA isolated in the Antarctic chiton Nuttallochiton mirandus. The anal- ysis of the sequences obtained and their chromo- somal location allows us to discuss not only their relationship but also their role in the karyological evolution of this species. Materials and methods The specimens of Nuttallochiton mirandus were collected in Terra Nova Bay, Antarctica. Total DNA was isolated from the foot of adults using methods following Canapa et al. (2000). Five micro- grams of genomic DNA was digested with the restriction enzymes EcoRV and DraI (Sigma, St Louis, MO, USA) according to the manufacturer_s instructions. For EcoRV digestion, after electropho- resis on 1.5% agarose gel, two bands were detected, 250 bp and 700 bp long respectively. These two Chromosome Research (2008) 16:907–916 # Springer 2008 DOI: 10.1007/s10577-008-1248-0