Complete mitochondrial genome sequences of the Arctic Ocean codfishes Arctogadus glacialis and Boreogadus saida reveal oriL and tRNA gene duplications

Abstract

We have determined the complete mitochondrial genome sequences of the codWshes Arctogadus glacialis and Boreogadus saida (Order Gadiformes, Family Gadidae). The 16,644 bp and 16,745 bp mtDNAs, respectively, contain the same set of 37 structural genes found in all vertebrates analyzed so far. The gene organization is conserved compared to other Gadidae species, but with one notable exception. B. saida contains heteroplasmic rearrangement-mediated duplications that include the origin of light-strand replication and nearby tRNA genes. Examination of the mitochondrial control region of A. glacialis, B. saida, and four additional representative Gadidae genera identiWed a highly variable domain containing tandem repeat motifs in A. glacialis. Mitogenomic phylogeny based on the complete mitochondrial genome sequence, the concatenated protein-coding genes, and the derived protein sequences strongly supports a sister taxa aYliation of A. glacialis and B. saida.

A Comprehensive Description and Evolutionary Analysis of 22 Grouper (Perciformes, Epinephelidae) Mitochondrial Genomes with Emphasis on Two Novel Genome Organizations

“…These are then often followed by deletions of the functionally redundant duplicated gene; however, there are examples of tRNAs retained in the mt genome after duplication. Beyond the additional tRNA-Ile and tRNA-Asp described here, the non-canonical tRNAs observed thus far in fish mt genomes include the extra tRNA-Ser downstream of ND5 in seabass Morone saxatilis [33], the extra tRNA-Met in the tRNA-IQM cluster in Pampus species [10] and the pseudo tRNA-Met in the same position in parrotfish Chlorurus sordidus [9], the additional tRNA-Asn and pseudo tRNA-Ala in the tRNA-WANCY cluster in polar cod Boreogadus saida [7], the duplicated tRNA-Thr and tRNA-Pro in the CR of Antarctic notothenioids [12]. While new tRNAs appear to be scattered through different mt regions, most in fact remain located at the rearrangement hotspots ( tRNA clusters and CR) in the fish mt genome.…”

“…However, recent work has shown that the fish mt genomes can differ from this canonical organization in both gene content and order, with several recognized hotspots of reorganization. These include the tRNA-WANCY cluster (W, Trp; A, Ala; N, Asn; C, Cys; Y, Tyr) located between ND2 and COI [7,8], the tRNA-IQM cluster (I, Ile; Q, Gln; M, Met) located between ND1 and ND2 [9,10], and the CR, usually involved in the translocation of ND6 and tRNA-Glu to CR [11,12]. In addition to these hotspots, large-scale reorganizations of the mt genome have also been observed in some fishes [13,14].…”

Genus Gadus (Gadidae): Composition, distribution, and evolution of forms

“…Here, the geo graphical isolation from the main herd of the Pacific cod due to the disjunction of the geographical ranges during the decrease of the water temperature in Sub boreal serves as the mechanism of evolution. The Greenland cod keeps the morphological, biological, and genetic similarity with the Pacific cod (Sick, 1965b;Breines et al, 2008;Stroganov, 2011b), but opposite to the latter, the Greenland cod does not form the swarming in the open ocean but inhabits the fjords and bays. In western Greenland and St. Lawrence Gulf, the geographical range of the Greenland cod overlaps the geographical range of the Atlantic cod, where they may compete for the food source.…”

Trophic ecology of sympatric Arctic gadoids, Arctogadus glacialis (Peters, 1872) and Boreogadus saida (Lepechin, 1774), in NE Greenland

“…Arctogadus and Boreogadus are phylogenetically close (Breines et al 2008;Pálsson et al 2009). Given the wide distribution of Boreogadus in Arctic waters, the occurrence of Arctogadus is always accompanied by Boreogadus but not vice versa.…”