Abstract
The complete mtDNA of Mallard Shengjin Lake Anas platyrhynchos is 16,604 bp in length, containing 13 protein-coding genes, two rRNAs, 22 tRNAs, and one D-loop. Mitochondrial genes of the Mallard Shengjin Lake A. platyrhynchos were arranged in the same order and orientation as those of other reported A. platyrhynchos and Chinese domestic ducks. The most frequent start codon of the protein-coding genes is ATG; TAA is the most frequent stop codon. The 12S rRNA and 16S rRNA genes are located between the tRNALeu and tRNAPhe genes and separated by the tRNAVal gene. The control region, located between the tRNAGlu and tRNAPhe genes is 1049 bp and is rich in A and T. Phylogenetic trees show Mallard Shengjin Lake A. platyrhynchos has close relative with Mallard Anas platyrhynchos (EU009397).
Anas platyrhynchos is a dabbling duck that breeds throughout the temperate and subtropical Americas, Eurasia, and North Africa, which winter in the middle and lower reaches of Yangtze River of China. This duck belongs to the family Anatinae of the waterfowl family Anatidae. Some scholars hold that Chinese domestic ducks originated from wild mallards (A. platyrhynchos) (Zhang et al. Citation2016; Qu et al. Citation2009; Li et al. Citation2010). In the present study, we sequenced the complete mtDNA of Mallard Shengjin Lake A. platyrhynchos. The feather samples were collected from A. platyrhynchos rescued in Shengjin Lake National Nature Reserve (E117°0′42.55″, N30°20′30.73″), Anhui Province of China in October 2017. The samples were stored at −20 °C in the Cancer Cell Biology Laboratory, School of Life Sciences, Anhui Medical University (Sample code is AHMU-WB20171022). The complete mitochondrial genome has been submitted to GenBank (accession number MK770342).
The complete mtDNA of Mallard Shengjin Lake A. platyrhynchos is 16,604 bp in length, containing 13 protein-coding genes, two rRNAs, 22 tRNAs, and one D-loop. Mitochondrial genes of the Mallard Shengjin Lake A. platyrhynchos was arranged in the same order and orientation as those of other reported A. platyrhynchos and Chinese domestic ducks (Zhang et al. Citation2016; Qu et al. Citation2009; Li et al. Citation2010; Tu et al. Citation2014; Xie et al. Citation2016). All the mitogenome genes were encoded on the H strand except for one protein-coding gene (ND6) and eight tRNA genes, similar to typical Anseriformes mtDNAs (Li et al. Citation2010; Liu et al. Citation2013; Citation2014; Xie et al. Citation2016). The composition of A, T, G, and C nucleotides in Mallard Shengjin Lake Anas platyrhynchos mtDNA is 29.2%, 22.2%, 15.8%, and 32.8%, respectively, indicating a remarkably high AT content (51.4%) and a low GC content (48.6%). This result is consistent with the AT bias generally observed in other Anatidae mt genomes (Zhang et al. Citation2016; Qu et al. Citation2009; Li et al. Citation2010; Liu et al. Citation2013, Citation2014; Xie et al. Citation2016). The start codon of the protein-coding genes is ATG, except for COX1, COX2, and ND5, which show a GTG start codon. All protein-coding genes, except for ND5, COI and COII, start with an ATG codon; TAA is the most frequent stop codon. The lengths of the 12S rRNA and 16S rRNA genes are 985 bp and 1602 bp, respectively, and are located between the tRNALeu and tRNAPhe genes and separated by the tRNAVal gene. The control region, located between the tRNAGlu and tRNAPhe genes is 1049 bp and is rich in A and T. This region is most likely to show sequence variations (Zhang et al. Citation2016).
Phylogenetic trees were estimated using ML and BI methods, based on the complete mtDNA of seven ducks, and corresponding Gallus gallus (NC_001323) sequence was used as an outgroup, sharing similar topologies and high node support values (). Mallard Shengjin Lake A. platyrhynchos has close relative with Mallard A. platyrhynchos (EU009397).
Figure 1. Phylogenetic trees based on complete mtDNA sequeces of seven ducks utilized the ML and BI methods. Numbers at each node are bootstrap values from three analyses (maximum likelihood/Bayesian inference).
Nucleotide sequence accession number
The complete mtDNA sequence of Mallard Shengjin Lake A. platyrhynchos has been assigned with GenBank accession number MK770342.
Disclosure statement
No potential conflict of interest was reported by the authors.
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References
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