Pseudopleuronectes herzensteini belonging to Pleuronectiformes (family Pleuronectidae ) is important in the fishery industry. However, the molecular biology of this valuable fish has hardly been reported. Thus, here we report the complete mitochondrial genome of P. herzensteini . The mitochondrial DNA (mtDNA) of P. herzensteini is 16,719 bp long and contains 13 mitochondrial protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and a putative control region between tRNA-P and tRNA-F distinguished by a single short noncoding region. Phylogenetic analysis using PCGs confirmed that this mtDNA sequence belongs to the family Pleuronectidae . This is the first study reporting the complete mitochondrial genome sequence of P. herzensteini .

Microstomus achne (Jordan and Starks, 1904) is an economically valuable flatfish belonging to the family Pleuronectidae and the only flatfish that inhabits Korea. Here, we report on the complete mitochondrial genome of M. achne and the phylogenetic relationship between close species. The mitogenome is 16,971 bp long and encodes 13 protein-coding genes (PCGs), 22 transfer RNAs, and two ribosomal RNAs. The phylogenetic analysis showed that M. achne clustered with Glyptocephalus stelleri , which supports the conclusion that M. achne belongs to the family Pleuronectidae. The results of this study provide a better understanding of M. achne .

The present study was conducted on the Nile tilapia (Oreochromis niloticus) and screened for single nucleotide polymorphisms (SNPs) in the muscle hormone genes myogenin (MyoG) and myostatin (MSTN). Samples were collected from the JangHang fish farm and categorized by body weight and sex. The average total weight was 1.02 kg for the 82 males and 0.63 kg for the 70 females. A body weight in the range of the average weight ±10% was considered as normal weight. Target regions of each gene were categorized, such as the promoter region, 5′-untranslated region (5′UTR) and 3′UTR. Genomic deoxyribonucleic acid (gDNA) was extracted, amplified, sequenced, aligned, and screened for the presence of nucleotide variations. Three SNPs, 1,875T>A, 1,892C>T, and 1,946A>G, and one insertion (TGA​CAT​ATT​TCC​CTC​ACA) at 2,138–2,145 were detected in the 3′UTR of the MyoG gene. However, within the MSTN gene, one insertion at 450 (T) and two SNPs at 536 (G>A and A>A) were found in the 5′UTR. In addition, four insertions at 1,278–1,279 (GT, T, TGT, and G) and one short tandem repeat (STR) at 1,129 (TG) in Exon 1, two SNPs at 4,438 (3′UTR; A>C and C>C), and two SNPs at 4,514 (3′UTR; G>A and A>A) were identified. Principal component analysis (PCA) and statistical analyses were performed to evaluate the relationships between the SNPs and body weight, forming 6 and 41 genotype blocks in the MyoG and MSTN genes, respectively. We found significant correlations between the SNPs and body weight traits for the effective genotype blocks GBG-1, GBG-3, and GBG-4 of MyoG and GBN-1, GBN-2, GBN-3, GBN-4, GBN-13, GBN-22, and GBN-24 of MSTN. These outcomes would be significant for fish breeding and may help obtain data for use in genetic marker kits. In some instances, genetic marker kits have a distinct advantage for improvement in genetics, parentage control, identification of species, and enhancing breeding stock and its applications in aquaculture.

Notostomum cyclostomum is a parasite that lays eggs on the snow crab shells and causes various diseases by parasitizing fish. Although there have been some studies on the life history of this parasite and the associated fish diseases, little is known about the molecular biology of this parasite. Thus, here we report the mitochondrial genome of N. cyclostomum , which is 16,972 bp long and contains 13 mitochondrial protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and a putative control region with a 92% AT-rich sequences between tRNA-R and tRNA-H . Phylogenetic analysis using 13 PCGs confirmed that N. cyclostoum belongs to the family Pisciodlidae . This is the first study revealing the complete mitochondrial genome sequence of N. cyclostomum .

Pleuronectidae is a well-studied familyin the order Pleuronectiformes. In contrast, genetic research on the flatfish Acanthopsetta nadeshnyi of the Pleuronectidae family is limited. This study reports the complete mitogenome of A. nadeshnyi . The mitogenome was 17,206 bases long and included 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and a putative control region. Phylogenetic analysis based on the nucleotide sequences of the 13 PCGs confirmed that A. nadeshnyi belongs to the Pleuronectidae family.