A Unique Mitochondrial Gene Block Inversion in Antarctic Trematomin Fishes: A Cautionary Tale

Many Antarctic notothenioid fishes have major rearrangements in their mitochondrial (mt) genomes. Here, we report the complete mt genomes of 3 trematomin notothenioids: the bald notothen (Trematomus (Pagothenia) borchgrevinki), the spotted notothen (T. nicolai), and the emerald notothen (T. bernacchii). The 3 mt genomes were sequenced using next-generation Illumina technology, and the assemblies verified by Sanger sequencing. When compared with the canonical mt gene order of the Antarctic silverfish (Pleuragramma antarctica), we found a large gene inversion in the 3 trematomin mt genomes that included tRNA(Ile), ND1, tRNA(Leu2), 16S, tRNA(Val), 12S, tRNA(Phe), and the control region. The trematomin mt genomes contained 3 intergenic spacers, which are thought to be the remnants of previous gene and control region duplications. All control regions included the characteristic conserved regulatory sequence motifs. Although short-read next-generation DNA sequencing technology has allowed the rapid and cost-effective sequencing of a large number of complete mt genomes, it is essential in all cases to verify the assembly in order to prevent the publication and use of erroneous data.

Automated summary

This study reports the complete mt genomes of three trematomin notothenioids, revealing major rearrangements and gene inversions compared to the canonical mt gene order of the Antarctic silverfish. The verification of the assemblies is crucial in preventing the publication and use of erroneous data.