Abstract
Gymnothorax minor has been often confused with G. reticularis because of the similar morphological characteristics. The complete mitochondrial genome sequence of G. minor is 16,575 bp in length, including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and two non-coding regions (CR and OL). All the protein-coding genes use ATG as start codon except COI using GTG. Most of them have complete stop codon as stop codon while COII and ND4 use T(aa). Phylogenetic analysis showed G. minor first clustered together with congeneric species and formed a monophyly in species of the genus Gymonthrax.
Gymnothorax minor (Temminck & Schlegel, 1846) has been often confused with Gymnothorax reticularis Bloch, 1795 because of the similar morphological characteristics between the two species. Now, G. minor is a new identification in China (Li et al. Citation2018) and it is necessary to clarify the classification position and reveal the genetic information of this species. Sufficient genetic data can be useful for rational utilization and conservation of G. minor resources. The voucher specimen was collected from the coastal water of Xiamen (24°26′N, 118°05′E) and deposited at the Fujian Institute of Oceanography. In this study, the complete mitochondrial genome (mitogenome) of G. minor was sequenced and phylogenetic relationship was reconstructed.
Long PCR and primer walking methods were employed to amplify the mitogenome sequence of G. minor with 37 pairs of primers (Miya and Nishida Citation1999). It was a typical circular form with 16,575 bp in length (GenBank number MK204283) and comprised two non-coding and 37 coding regions. The overall base composition was 29.4% for A, 26.2% for T, 26.7% for C, and 17.7% for G, exhibiting a slight A + T rich feature (55.6%). The 37 coding regions included 13 protein-coding genes (PCGs), 22 tRNAs genes, two rRNA genes (12S and 16S), and two mainly non-coding regions (control region/CR and light-strand replication origin/OL).
Total length of 13 PCGs was 11,480 bp and they encoded 3815 amino acids. Except for ND6 and eight tRNAs genes, all other genes were encoded on the H-strand. Except for COI (GTG) gene, other 12 PCGs started with typical ATG codon (Slack et al. Citation2003). Three types of complete stop codon (TAA, AGA, or TAG) were found in 11 PCGs including ND1, ND2, COI, ATP8, ATP6, COIII, ND3, ND4L, ND5, ND6, and Cyt b while ND4 and COII had only incomplete stop codon T(aa) that might be terminated by post-transcriptional polyadenylation (Ojala et al. Citation1980). The putative OL was 28 bp long, located in the WANCY region (tRNATrp-tRNAAla-tRNAAsn-tRNACys-tRNATyr). The CR of G. minor was sequenced to be 966 bp in length located between the tRNAPro and the tRNAPhe genes.
Phylogenetic analysis of G. minor was performed based on the mitogenome sequences of this species and five other related fish species using MEGA 6.06 (Tamura et al. Citation2013). The result of NJ tree showed that G. minor first clustered together with three congeneric species and formed a monophyly in species of the genus Gymonthrax with high bootstrap values, and then constituted a sister group with other genus in the family Muraenidae ().
Figure 1. Phylogenetic relationship of G. minor. The cited mitogenome sequenced are downloaded from GenBank and the phylogenic tree is constructed by neighbor-joining method with 100 bootstrap replicates. Bootstrap values of >50% are shown above the node.
Disclosure statement
No potential conflict of interest was reported by the authors.
Additional information
Funding
References
- Li Y, Zhang LY, Zhao LL, Feng J, Loh KH, Zheng XQ, Lin LS. 2018. New identification of the moray eel Gymnothorax minor (Temminck & Schlegel, 1846) in China (Anguilliformes, Muraenidae). ZooKeys. 752:149–161.
- Miya M, Nishida M. 1999. Organization of the mitochondrial genome of a deep-sea fish, Gonostoma gracile (Teleostei: Stomiiformes): first example of transfer RNA gene rearrangements in bony fishes. Mar Biotechnol. 1:416–426.
- Ojala D, Merkel C, Gelfand R, Attardi G. 1980. The tRNA genes punctuate the reading of genetic information in human mitochondrial DNA. Cell. 22:393–403.
- Slack KE, Janke A, Penny D, Arnason U. 2003. Two new avian mitochondrial genomes (penguin and goose) and a summary of bird and reptile mitogenomic features. Gene. 302:43–52.
- Tamura K, Stecher G, Peterson D, Filipski A, Kumar S. 2013. MEGA6: Molecular Evolutionary Genetics Analysis version 6.0. Mol Biol Evol. 30:2725–2729.