Complete mitochondrial genome of Paramisgurnus dabryanus

Paternal Mitochondrial DNA Leakage in Natural Populations of Large-Scale Loach, Paramisgurnus dabryanus

Animal mitochondrial DNA is usually considered to comply with strict maternal inheritance, and only one mitochondrial DNA haplotype exists in an individual. However, mitochondrial heteroplasmy, the occurrence of more than one mitochondrial haplotype, has recently been reported in some animals, such as mice, mussels, and birds. This study conducted extensive field surveys to obtain representative samples to investigate the existence of paternal inheritance of mitochondrial DNA (mtDNA) in natural fish populations. Evidence of paternal mitochondrial DNA leakage of P. dabryanus was discovered using high-throughput sequencing and bioinformatics methods. Two distinct mitochondrial haplotypes (16,569 bp for haplotype I and 16,646 bp for haplotype II) were observed, differing by 18.83% in nucleotide sequence. Phylogenetic analysis suggests divergence between these haplotypes and potential interspecific hybridization with M. anguillicaudatus, leading to paternal leakage. In natural populations of P. dabryanus along the Yangtze River, both haplotypes are present, with Type I being dominant (75% copy number). Expression analysis shows that Type I has higher expression levels of ND3 and ND6 genes compared to Type II, suggesting Type I's primary role. This discovery of a species with two mitochondrial types provides a model for studying paternal leakage heterogeneity and insights into mitochondrial genome evolution and inheritance.

Complete mitochondrial genome of natural diploid loaches Misgurnus anguillicaudatus from the Taihu Lake

Misgurnus anguillicaudatus is a highly valued, aquaculture-relevant food fish in East Asian countries. Because of overfishing and environmental pollution, the number of wild Taihu loach has been sharply decreased in these years. In this study, the complete mitochondrial genome of Taihu loach was obtained by PCR. The genome is 16,646 bp in length, including 2 ribosomal RNA genes. Thirteen proteins-coding genes, 22 transfer RNA genes, and a non-coding control region, the gene composition and order of which was similar to most reported from other vertebrates. Sequence analysis showed that the overall base composition is 29.8% for A, 28.2% for T, 25.7% for C, and 16.3% for G. The phylogenetic tree showed that Misgurnus family got together for one branch, which includes Taihu M. anguillicaudatus, and the other loaches had their own branches. Also the mitochondrial genome sequence of M. anguillicaudatus were aligned by BLAST, compared with Cobitinae the sequence similarity could reach >94%, and the similarity to Misgurnus was >99%.

Molecular characteristics of mitochondrial DNA and phylogenetic analysis of the hybrid loach of Misgurnus anguillicaudatus (female) and Paramisgurnus dabryanus ssp. (male)

The hybrid loach of Misgurnus anguillicaudatus (female) and Paramisgurnus dabryanus ssp. (male) has the desirable trait of growth performance. Recently, farming scale of this hybrid has been gradually increased in Asia, suggesting a promise of a new variety for loach. In this study, the complete mitochondrial genome of the hybrid loach was obtained by PCR. The genome is 16,646 bp in length, including two ribosomal RNA genes. Thirteen proteins-coding genes, 22 transfer RNA genes, and a non-coding control region, the gene composition and order of were similar to most reported from other vertebrates. Sequence analysis showed that the overall base composition is 29.8% for A, 28.3% for T, 25.6% for C, and 16.3% for G. The phylogenetic tree showed that Misgurnus family got together for one branch, which includes this hybrid loach, and the other loaches had their own branches. Also the mitochondrial genome sequences of the hybrid loach were aligned by BLAST, compared with Cobitidae the sequence similarity could reach >95%, and the similarity to Misgurnus was >99%. The hybrid loach follows the matrilineal inheritance.

Complete mitochondrial genome of Taiwanese loach, Paramisgurnus dabryanus ssp. (Cobitinae)

Taiwanese loach was bred in Formosa and then widely cultivated in China. Because of overfishing and environmental pollution, the number of wild Taiwanese loach has been sharply decreased in these years. Also the taxonomic status of Taiwanese loach is still unclear. In this study, the complete mitochondrial genome of Taiwanese loach was obtained by PCR. The genome is 16,569 bp in length, including 2 ribosomal RNA genes, 13 proteins-coding genes, 22 transfer RNA genes, and a non-coding control region, the gene composition and order of which was similar to most reported from other vertebrates. Sequence analysis showed that the overall base composition is 29.5% for A, 27.5% for T, 26.4% for C, and 16.6% for G. The sequence is a slight A + T bias of 57.0%. By analyzing phylogenetic analysis and BLAST, the similarity to Paramisgurnus was >99%, we dare to speculate that the Taiwanese loach cultivated in China was a subspecies of P. dabryanus. Mitogenome information from this study could be a useful basis for conservation and phylogenetics of Taiwanese loach, P. dabryanus ssp.

Complete mitochondrial genome of the hybrid loach of Paramisgurnus dabryanus ssp. (female) and Misgurnus anguillicaudatus (male)

The hybrid loach of P. dabryanus ssp. (female) and M. anguillicaudatus (male) has the desirable trait of growth performance. There is no report of the complete genome of this hybrid. In this study, the complete mitochondrial genome of this hybrid loach was obtained, and the genome is 16,569 bp in length, including two ribosomal RNA genes. Thirteen proteins-coding genes, 22 transfer RNA genes, and a non-coding control region, the gene composition and order of which was similar to most reported from other vertebrates. Sequence analysis showed that the overall base composition is 29.5% for A, 27.5% for T, 26.4% for C, and 16.6% for G. The sequence is a slight A + T bias of 57.0%. The phylogenetic tree showed that the hybrid loach to be one of Paramisgurnus, and the relationships of M. anguillicaudatus were closer. Also the mitochondrial genome sequence of loach were aligned by BLAST, compared with Cobitinae the sequence similarity could reach >90%, and the similarity to Paramisgurnus was >99%. Mitogenome information from this study could be a useful basis for conservation and phylogenetics of this hybrid loach.

Mitochondrial genome sequence of Paramisgurnus dabryanus from the Yellow River estuary: implication for Cobitidae phylogeny

Paramisgurnus dabryanus Sauvage (Cobitidae, Cypriniformes) is a native large-scale loach widely distributed in main inland freshwater systems of China. The complete mitochondrial genome sequence of P. dabryanus from the Yellow River (YR) estuary was characterized in the present study. The circular mitogenome is 16 570 bp in size and contains two ribosomal RNA genes, 22 transfer RNA genes, and 13 protein-coding genes. The overall A + T content is 56.64% in the range of other Cobitidae studied. The mitogenome of P. dabryanus YR has an overall nucleotide sequence identity of 96.9% with that from Zhejiang, and 89.2% with that from Hubei. All the Misgurnus and Paramisgurnus species were clustered into two Misgurnus/Paramisgurnus complex clades with high bootstrap values based on the whole mitogenome sequences. The mitochondrial phylogenomic analysis indicates that the relationships in Cobitidae are inconsistent with the current classification system and taxonomic revision is required on the basis of molecular phylogeny and morphology.