title: Mitochondrial genome of the Christmas tree worm Spirobranchus giganteus (Annelida: Serpulidae) reveals a high substitution rate among annelids.
abstract: Here we describe, for the first time, the mitochondrial genome of Spirobranchus giganteus (Annelida: Serpulidae) and compare it with all available annelid mitogenomes. The entire mitogenome has 22,058bp in length and bears 12 protein-coding genes (the ATP8 gene is missing), two rRNA, and 24 tRNA genes. The nucleotide composition and GC-skew are surprisingly different from those reported for other annelids. In addition, the pairwise genetic distances between the mitogenomes of S. giganteus and other annelids are higher than the distances for all annelid taxa analyzed. This result is consistent with a faster rate of mitochondrial sequence evolution in S. giganteus, which may explain the difficulty in obtaining PCR products with the available primers. The mitochondrial gene order of S. giganteus was remarkably different not only from that of the Sedentaria lineage, which includes S. giganteus, but also from the mitochondrial gene order of other major annelid lineages. The mitogenome of S. giganteus has no repetitive motifs despite its long control region (4769bp), but genes are shorter and have a lower AT content than other members of Annelida. Finally, we show that mitochondrial gene order rearrangements can directly correlate to variations in gene length.
authors.affiliation: Universidade Federal do Rio de Janeiro, CCS, Instituto de Biologia, Departamento de Genética, Av. Carlos Chagas Filho 373, Sala A2-97, Bloco A, Ilha do Fundão, Rio de Janeiro, RJ 21941-570, Brazil. Electronic address: victorcseixas@gmail.com.
authors.forename: Victor Corrêa
authors.initials: VC
authors.lastname: Seixas
authors.affiliation: Universidade Federal do Rio de Janeiro, CCS, Instituto de Biologia, Departamento de Genética, Av. Carlos Chagas Filho 373, Sala A2-97, Bloco A, Ilha do Fundão, Rio de Janeiro, RJ 21941-570, Brazil.
authors.forename: Claudia Augusta de Moraes
authors.initials: CA
authors.lastname: Russo
authors.affiliation: Universidade Federal do Rio de Janeiro, CCS, Instituto de Biologia, Departamento de Zoologia, Av. Carlos Chagas Filho 373, Sala A0-108, Bloco A, Ilha do Fundão, Rio de Janeiro, RJ 21941-902, Brazil.
authors.forename: Paulo Cesar
authors.initials: PC
authors.lastname: Paiva
mesh_terms: D000818:Animals; D000845:Annelida / Q000145:classification / Q000235:genetics*; D001482:Base Composition; D005075:Biological Evolution; D002874:Chromosome Mapping; D004272:DNA, Mitochondrial / Q000235:genetics*; D023061:Gene Order; D015321:Gene Rearrangement; D050259:Genes, Mitochondrial; D059646:Genome Size; D054629:Genome, Mitochondrial; D008928:Mitochondria / Q000235:genetics; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial
keywords: Gene length evolution; Gene order; High-throughput sequencing; Mitogenome; Sabellida; Sequence evolution