Sequence of PRAT Satellite DNA “Frozen” in Some Coleopteran Species Brankica Mravinac, Miroslav Plohl, Nevenka Mes ˘trovic ´, Ður  ica Ugarkovic ´ Department of Molecular Genetics, Ruer Bos ˘kovic ´ Institute, Bijenic ˘ka 54, P.O. Box 180, HR-10002 Zagreb, Croatia Received: 26 August 2001 / Accepted: 13 November 2001 Abstract. The intriguing diversity of highly abundant satellite repeats found even among closely related spe- cies can result from processes leading to dramatic changes in copy number of a particular sequence in the genome and not from rapid accumulation of mutations. To test this hypothesis, we investigated the distribution of the PRAT satellite DNA family, a highly abundant major satellite in the coleopteran species Palorus ratze- burgii, in eight species belonging to the related genera ( Tribolium, Tenebrio, Latheticus ), the subfamily (Pimeliinae), and the family (Chrysomelidae). Dot blot analysis and PCR assay followed by Southern hybridiza- tion revealed that the PRAT satellite, in the form of low-copy number repeats, was present in all tested spe- cies. The PRAT satellite detected in the species Pimelia elevata has been sequenced, and compared with previ- ously cloned PRAT monomers from Palorus ratzeburgii and Palorus subdepressus. Although the two Palorus species diverged at least 7 Myr ago, and the subfamily Pimeliinae separated from the genus Palorus 50–60 Myr ago, all PRAT clones exhibit high mutual homology, with average variability relative to the common consen- sus sequence of 1.3%. The presence of ancestral muta- tions found in PRAT clones from all three species as well as the absence of species diagnostic mutations illustrate extremely slow sequence evolution. This unexpectedly high conservation of PRAT satellite DNA sequence might be induced by a small bias of turnover mecha- nisms favoring the ancestral sequence in the process of molecular drive. Key words: Insecta — Coleoptera — Satellite DNA — Repetitive DNA — Evolution — Molecular drive — Concerted evolution Introduction Satellite sequences are highly abundant, tandemly re- peated DNA components of heterochromatin, character- istic of all eukaryotic species (Miklos 1985). Although satellite sequences have been characterized in a number of species, no sequence-specific role has been definitive- ly established for them. They could be functional as a structural element in the nucleus influencing chromo- some organization and centromere function by binding specific proteins (Csink and Henikoff 1998). It has been postulated that satellite DNAs exhibit coding potential based on short sequence motifs like the CENP-B box, or on specific higher order structures (Vogt 1992). The tran- scription of satellite DNAs has been reported in different species (Rouleux-Bonnin et al. 1996; Wang et al. 1999). The cellular function of the transcripts is not clear and it is proposed that they have structural rather than protein coding function (Renault et al. 1999). Satellite DNAs usually show extreme diversity in se- quence, copy number or both, even among closely re- lated species, and are considered a fast evolving part of the eukaryotic genome. However, there are examples of satellite sequences that are well conserved between spe- cies. A common satellite DNA family within the Dro- sophila virilis group exhibits a similar level of intra- and interspecific sequence variability, although these species diverged at least 20 Myr ago (Heikkinen et al. 1995). In the coleopteran genus Pimelia, six species share the same Correspondence to: Dr. Ð. Ugarkovic ´; email: ugarkov@rudjer.irb.hr J Mol Evol (2002) 54:774–783 DOI: 10.1007/s0023901-0079-9 © Springer-Verlag New York Inc. 2002