The non-regular orbit: three satellite DNAs in Drosophila martensis (buzzatii complex, repleta group) followed three different evolutionary pathways.
The genome of species from the buzzatii cluster (buzzatii complex, repleta group) is hosted by a number of satellite DNAs (satDNAs) showing contrasting structural characteristics, genomic organization and evolution, such as pBuM-alpha (~190 bp repeats), pBuM-alpha/beta (~370 bp repeats) and the DBC-150 (~150 bp repeats). In the present study, we aimed to investigate the evolution of these three satDNAs by looking for homologous sequences in the genome of the closest outgroup species: Drosophila martensis (buzzatii complex). After PCR, we isolated and sequenced 9 alpha, 8 alpha/beta and 11 DBC-150 sequences from this species. The results were compared to all pBuM and DBC-150 sequences available in literature. After D. martensis split from the buzzatii cluster some 6 Mya, the three satDNAs evolved differently in the genome of D. martensis by: (1) maintenance of a collection of major types of ancestral repeats in the genome (alpha); (2) fixation for a single major type of ancestral repeats (alpha/beta) or (3) fixation for new divergent species-specific repeat types (DBC-150). Curiously, D. seriema and D. martensis, although belonging to different and allopatric clusters, became independently fixed for the same major type of alpha/beta ancestral repeats, illustrating a rare case of parallelism in satDNA evolution. The contrasting pictures illustrate the diversity of evolutionary pathways a satDNA can follow, defining a "non-regular orbit" with outcomes difficult to predict.
Kuhn
Gustavo C S
GC
Departamento de Genética e Evolução, Universidade Federal de São Carlos, Via Washington Luís, Km 235, São Carlos, SP 13565-905, Brazil. gcskuhn@ufscar.br
Schwarzacher
Trude
T
Heslop-Harrison
John S
JS
D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000235:genetics; D017931:DNA Primers; D004276:DNA, Satellite / Q000235:genetics*; D004330:Drosophila / Q000235:genetics*; D019143:Evolution, Molecular; D016678:Genome; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid
D017931:DNA Primers; D004276:DNA, Satellite; D004247:DNA