Identification of the complete mitochondrial genome of Garra pingi pingi (Cypriniformes, Cyprinidae)

Novel Gene Rearrangement in the Mitochondrial Genome of Three Garra and Insights Into the Phylogenetic Relationships of Labeoninae

Complete mitochondrial genomes (mitogenomes) can provide valuable information for phylogenetic relationships, gene rearrangement, and molecular evolution. Here, we report the mitochondrial whole genomes of three Garra species and explore the mechanisms of rearrangements that occur in their mitochondrial genomes. The lengths of the mitogenomes’ sequences of Garra dengba, Garra tibetana, and Garra yajiangensis were 16,876, 16,861, and 16,835, respectively. They contained 13 protein-coding genes, two ribosomal RNAs, 22 transfer RNA genes, and two identical control regions (CRs). The mitochondrial genomes of three Garra species were rearranged compared to other fish mitochondrial genomes. The tRNA-Thr, tRNA-Pro and CR (T-P-CR) genes undergo replication followed by random loss of the tRNA-Thr and tRNA-Pro genes to form tRNA-Thr, CR1, tRNA-Pro and CR2 (T-CR-P-CR). Tandem duplication and random loss best explain this mitochondrial gene rearrangement. These results provide a foundation for future characterization of the mitochondrial gene arrangement of Labeoninae and further phylogenetic studies.

The complete mitochondrial genome of Sarcocheilichthys davidi and its phylogeny

Sarcocheilichthys davidi is a small-size ornamental freshwater species. In the present study, the complete mitochondrial genome of S. davidi was first determined using the next-generation sequencing technology. The result showed that the circular mitogenome was 16,675 bp in length, contained 13 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and two non-coding regions: origin of light-strand replication (OL) and displacement loop locus (D-loop). In addition to ND6 and eight tRNA genes, most mitochondrial genes were encoded on the heavy strand. Furthermore, the overall base composition was 29.97% A, 26.12% T, 26.86% C, 17.04% G, respectively, and showed AT-rich feature (56.09%). Moreover, phylogenetic analysis based on the tandem 13 PCGs nucleotide sequences indicated that S. davidi had a close relationship with S. snigripinnis and S. variegatus wakiyae. The complete mitogenome sequence of S. davidi would contribute to the better understanding of molecular systematics, selection, conservation, species identification and evolution of this species.