Molecular characterization of SSS139, a new satellite DNA family in sibling species of the Drosophila buzzatii cluster

Abstract

We characterized sequences of a novel SSS139 RsaI satellite DNA family in Drosophila gouveai and Drosophila seriema, two members of the Drosophila buzzatii cluster (D. repleta group). The sequences were AT-rich (69%) with a monomer unit length of about 139 bp and contained two direct subrepeats of 14 bp and 16 bp, suggesting that it might have originated by the duplication of smaller sequences. Southern and dot-blot hybridization analyses also detected SSS139 in other Drosophila buzzatii cluster species (D. koepferae, D. antonietae, D. borborema and D. serido) but not in D. buzzatii. These results agree with the marginal phylogenetic position of D. buzzatii within the D. buzzatii cluster.Key words: Drosophila buzzatii cluster, molecular evolution, repetitive DNA, satellite DNA, SSS139 satellite DNA. Satellite DNA consists of highly repetitive and tandemly arranged DNA sequences (Charlesworth et al., 1994) which are considered the main components of constitutive heterochromatin and are usually located in the centromeric regions of chromosomes and, less frequently, in telomeres (Charlesworth et al., 1994;Ugarkovic and Plohl, 2002). Satellite DNAs are heterogeneous and no general function has been attributed to this DNA class. However, despite the terminology "junk DNA" frequently associated with these sequences (Orgel and Crick, 1980), several biological roles have been suggested for some satellite DNA families, such as regulation of both heterochromatin condensation and genetic expression (reviewed by Ugarkovic, 2005). Moreover, satellite DNAs are involved in the maintenance of functional centromeres in mammals (Willard, 1990) and might also be related to the late replication of centromeres (Csink and Henikoff, 1998).The satellite DNA sequences evolve in a concerted manner (Dover, 1982) and the main molecular mechanisms involved in its evolution are slippage replication, unequal crossing-over, gene conversion and rolling circle replication, which can, in general, induce a strong intra-specific homogenization of satellite DNA sequences and interspecific divergence (Dover, 1982;Charlesworth et al., 1994).The monomers of a satellite DNA can be speciesspecific (Bachmann et al., 1994;Abadon et al., 1998) or shared among phylogenetically related species (Watabe et al., 1997;Lopez-Flores et al., 2004;Kuhn and Sene, 2005). Though there are examples of extremely conserved satellite DNA sequences among species that diverged for long evolutionary periods (de la Herrán et al., 2001;Mravinac et al. 2002), most satellite DNA shared among species presents high evolutionary rates, acquiring diagnostic mutations for each species.The Drosophila buzzatii cluster (D. repleta group, D. buzzatii complex) is a monophyletic group composed by cactophilic and sibling species that are naturally endemic to South America . Currently, the D. buzzatii cluster is composed of seven nominal Drosophila species (D. antonietae, D. borborema, D. buzzatii, D. gouveai, D. koepferae, D. serido and D. seriema). According to aedeagus and wing mor...

Evolutionary dynamics and sites of illegitimate recombination revealed in the interspersion and sequence junctions of two nonhomologous satellite DNAs in cactophilic Drosophila species

“…This is a monophyletic group comprising seven closely-related cactus-breeding species of South American origin: D. buzzatii, D. koepferae, D. serido, D. antonietae, D. gouveai, D. seriema and D. borborema (Manfrin and Sene, 2006). These species share at least five abundant unrelated satDNAs, three of them formally described (Kuhn and Sene, 2005;Kuhn et al, 2007;Franco et al, 2008). Two of these satDNA families with contrasting evolutionary and structural characteristics have been studied in more detail.…”

Dissecting the Satellite DNA Landscape in Three CactophilicDrosophilaSequenced Genomes

“…This family is abundant in D. seriema but virtually absent in D. buzzatii ( Kuhn et al 2007 ). Finally, the third satDNA family, named SSS13 9, with 139-bp-long repeat units is abundant in D. seriema but absent in D. buzzatii ( Franco et al 2008 ). There is no significant sequence similarity among pBuM , DBC-150, and SSS139 satDNA repeats, suggesting that these families have independent evolutionary origins.…”

Intra- and interspecific divergence in the nuclear sequences of the clock gene period in species of the Drosophila buzzatii cluster

“…Studies based on nuclear markers (Rodriguez‐Trelles et al. 2000; Franco et al. 2008a) and aedeagus and wing morphology (Moraes and Sene 2007; Manfrin and Sene 2006) suggest that D. koepferae is more closely related to the so‐called serido sibling set than to D. buzzatii .…”

“…Based on mitochondrial DNA sequence data, D. koepferae and D. buzzatii appear as sister taxa. Studies based on nuclear markers (Rodriguez-Trelles et al 2000;Franco et al 2008a) and aedeagus and wing morphology (Moraes and Sene 2007;Manfrin and Sene 2006) suggest that D. koepferae is more closely related to the so-called serido sibling set than to D. buzzatii. These contrasting patterns could be explained as a result of shared polymorphisms between the D. koepferae and D. buzzatii genomes, such as the shared polymorphism in the period gene, as observed in this study (Table S2).…”