Characterization and phylogenetic analysis of the mitochondrial genome of Sarcocheilichthys sinensis (Bleeker) from Baima Hu Lake.

Sarcocheilichthys sinensis (Bleeker), is a small-sized benthopelagic fish with ornamental value. In the present study, the complete mitochondrial genome of S. sinensis was sequenced and determined. The complete mitogenome of S. sinensis was 16,683 bp in length, consisting of 22 tRNA genes, 13 protein-coding genes, 2 rRNA genes, and 2 non-coding regions. The overall base composition of the S. sinensis mitogenome is 30.50% A, 26.28% T, 26.60% C, and 16.61% G, exhibiting obvious AT bias (56.79%). The phylogenetic analysis showed that S. sinensis clustered in genus Sarcocheilichthys. Present study provides useful data to population genetics and conservation biology of Sarcocheilichthys fishes.

The Chinese lake gudgeon, Sarcocheilichthys sinensis (Bleeker), is a small-sized benthopelagic fish distributed widely in various region of China (Song and Ma 1994; Zhang et al. 2008; Li et al. 2011; Zhu et al. 2017). It is an omnivorous and edible fish with ornamental value (Guo et al. 1995; Song and Ma 1996; Huan et al. 2010; Li et al. 2011). Baima Hu Lake is one of the most famous lakes in Shaoxing City, East China. Although S. sinensis is a common fish in East Asia (Hosoya1982; Barabanshchikov 2004; Yuan et al. 2010; Shen et al. 2017), little is known about it in Baima Hu Lake.

The mitochondrial genome (mitogenome) could be useful data in population genetics and conservation biology studies, due to rich signals from its gene arrangement and sequence information (Liu and Cui 2009; Chen et al. 2013; Yang et al. 2015; Cui et al. 2019).

Herein, a new complete mitogenome of S. sinensis (GenBank accession no. MN711646) was characterized. Sarcocheilichthys sinensis was collected from Baima Hu Lake, Zhejiang Province of China (33°13′47.7′′N, 119°08′49.4′′E), and preserved in 99% ethanol in Shaoxing Aquatic Service Platform (accession no. SXAF191122). Total DNA was extracted and used as template, the PCR amplification was carried out and the protocols were: initial denaturation at 94 °C for 5 min, followed by 37 cycles of amplification (93 °C for 50 s, 55–57 °C for 25 s, and 72 °C for 90 s) and 1 final cycle of 8 min at 72 °C.

The complete mitochondrial genome of S. sinensis is 16,683 bp in length, consists of 13 protein-coding genes (PCDs), 22 tRNA genes, 2 rRNA genes, and 2 non-coding regions. Among these genes, 12 PCDs (ND1–5 and ND4L, COXI–III, ATP6, ATP8, and CytB), 14 tRNA genes (tRNA, tRNA, tRNA, tRNA, tRNA, tRNA, tRNA, two tRNA genes, tRNA, tRNA, tRNA, tRNA, and tRNA), and 2 rRNA genes (12S rRNA and 16S rRNA) were encoded on the H-strand, while other genes including one PCD (ND6) were encoded on the L-strand. The gene order within the complete mitogenome of S. sinensis is similar to other vertebrate species (Zhu et al. 2019).

The overall base composition of the S. sinensis mitogenome is 30.50% A, 26.28% T, 26.60% C, and 16.61% G, respectively, exhibiting obvious AT bias (56.79%), which is similar to other vertebrate mitogenomes (Yang et al. 2015; Li et al. 2016). The 12S rRNA gene (960 bp) and 16S rRNA (1685 bp) gene are located between two tRNA genes (tRNA and tRNA), and are separated by the tRNA gene, which is similar to most of vertebrates mitogenomes (Wang et al. 2016).

The phylogenetic tree was constructed using the neighbor-joining method. The results showed that S. sinensis is clustered with other S. sinensis, and clustered in genus Sarcocheilichthys with other Sarcocheilichthys fishes including Sarcocheilichthys davidi, Sarcocheilichthys kiangsiensis, Sarcocheilichthys lacustris, Sarcocheilichthys nigripinnis, Sarcocheilichthys parvus, and Sarcocheilichthys variegatus (Figure 1). While it showed distant kinship with other Cyprinidae fishes. This study provides useful data to population genetics and conservation biology of Sarcocheilichthys fishes.

Figure 1.

The phylogenetic analysis of Sarcocheilichthys sinensis and other Cyprinidae fishes based on the mitogenome sequences.