Complete mitochondrial genome of Acheilognathus signifer (Cypriniformes, Cyprinidae): comparison of light-strand replication origins from six Acheilognathus species

Mitochondrial genome of Acheilognathusbarbatulus (Cypriniformes, Cyprinidae, Acheilognathinae): characterisation and phylogenetic analysis

Acheilognathusbarbatulus is distributed in Yangtze River, Yellow River and Pearl River systems in China. Genome data can help to understand the phylogenetic relationships of A.barbatulus, but its complete mitochondrial genome has not been published. We determined the complete mitochondrial genome structure and characteristics of this species and constructed a comprehensive phylogenetic tree, based on mitochondrial genome data of several species of Acheilognathus, Rhodeus and Pseudorasboraparva. The complete length of the mitochondrial genome of A.barbatulus is 16726 bp. The genome is a covalently closed double-stranded circular molecule containing 13 protein-coding genes, two ribosomal RNAs, 22 transfer RNAs, a D-loop and a light strand replication initiation region. The base composition of the complete mitochondrial genome is A (29.33%) > T (27.6%) > C (26.12%) > G (16.95%), showing a strong AT preference and anti-G bias. All 13 PCGs have different degrees of codon preference, except for cytochrome c oxidase 1, which uses GTG as the start codon. All the PCGs use ATG as the start codon and the stop codon is dominated by TAG. The encoded amino acids Leu and Ser exist in two types, whereas the rest are all present as one type, except for tRNASer (GCT), which lacks the D-arm and has an incomplete secondary structure, all other tRNAs can be folded to form a typical cloverleaf secondary structure. Based on the 13 PCG tandems, the Maximum Likelihood and Bayesian trees were constructed, based on the concatenated sequence of 13 PCGs for the genera Acheilognathus and Rhodeus, with Pseudorasboraparva as the outgroup. Acheilognathusbarbatulus, Acheilognathustonkinensis and Acheilognathuscf.macropterus were clustered together and the most closely related. The results of this study enrich the mitochondrial genomic data of Acheilognathus and provide molecular and genetic base information for species conservation, molecular identification and species evolution of Acheilognathinae.

Identification and analysis of the complete mitochondrial genome of Acheilognathus omeiensis (Cypriniformes, Cyprinidae)

Acheilognathus omeiensis is a small-size freshwater ornamental fish. In this study, the complete mitochondrial genome sequence of A. omeiensis was first determined. This mitogenome was 16,774 bp in length and contained 13 protein-coding genes (PCGs), 22 tRNA genes, 2 rRNA genes, and 2 main noncoding regions. Most mitochondrial genes were encoded on the H-strand, except for ND6 and eight tRNA genes. The base composition was 28.97% A, 27.72% T, 26.02% C, and 17.29% G, with 56.69% AT, respectively. Phylogenetic tree was constructed based on the nucleotide sequence of 13 PCGs of A. omeiensis and closely related 12 species ticks to assess their phylogenic relationship and evolution. These data should be helpful for a better understanding of the mitochondrial genomic diversities and evolution in fish as well as novel genetic markers for studying population genetics and species identification.

Complete mitochondrial genome of the freshwater fish, Acheilognathus somjinensis (Cypriniformes, Cyprinidae)

The complete mitochondrial genome was sequenced from the freshwater cyprinid fish, Acheilognathus somjinensis. The genome sequence is 16,569 bp in size, and the gene order and contents are identical with the congeneric species A. yamatsutae, A. koreensis and A. intermedia. Of 13 protein-coding genes (PGCs), three genes (CO2, CO3, Cytb) had an incomplete stop codon as shown in the genus Acheilognathus. The base composition of A. somjinensis showed anti-G bias (13.58% and 12.21%) on the second and third positions of PCGs but not high (4.8% on the third position of PCGs) as present in the river lamprey, Lampetra japonica.

Complete mitochondrial genome of the Korean bitterling Acheilognathus koreensis (Cypriniformes; Cyprinidae)

The complete mitochondrial genome was sequenced from the Korean bitterling Acheilognathus koreensis. The genome sequence was 16,563 bp in size, and the gene order and contents were identical with the same genera Acheilognathus signifier and other previously reported fish mitochondrial genomes. Of 13 protein-coding genes (PCGs), four genes (CO2, CO3, ND4, and Cytochrome b) had incomplete stop codons. The base composition of A. koreensis showed anti-G bias (13.69%) on the third position of PCGs.