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Determination of this study the the big mouth Jian (Psettodes erumei) mitochondrial genome sequence to 17,315 bp in length and contains a total of 22 kinds of tRNA genes, two rRNA genes, 13 protein-coding genes and two non-coding region. Placement of each gene in the mitochondria, the same gene order of vertebrates, where L chain encodes only eight tRNA and ND6 gene. Analysis big mouth Jian genome and each gene fragment base composition of the whole AT content greater than GC. tRNA and rRNA gene base composition bias smaller, protein-coding genes showed a significant anti-G bias, and mainly in the third codon. In the L chain, and calculating the standard GC-skew = -0.32, the AT-Skew = 0.08, found vertebrate GC bias. Analyzing large mouth Qian each gene sequence characteristics: tRNAs length variation insertions and deletions; protein coding genes in addition to CO Ⅰ and CO Ⅲ respectively GTG and CAC for the start codon, and the remaining 11 genes starting password sub are for standard from The initiation codon ATG. Termination codons except TAA, TAG, and their corresponding incomplete termination codon T, TA outside, ND1 AGG as a stop codon, this phenomenon is less common in fish; 22 tRNA tRNAscan-SE recognizes only the 21 secondary structure of the tRNA, tRNA-Set (GCT) is identified software RNAstructure 4.5 clover structure of its irregular. , The variation of the number of bases in the secondary structure of the tRNA genes exist in DHU ring, instead of pairing bases mainly exist in the receiving arm; analysis of 10 Pleuronectiformes fish start replication region of the light chain (O_L ) base composition and structure, at least the big mouth Qian AT content, only 16.9%, 36.5% followed by Japanese flounder, and other species were higher than 50%. While in the the Pleuronectiformes fish, O_L typical \Designed two pairs of primers to amplify the control region sequences of the large port Qian left eye and right eye of two individuals. Two individuals were present at the 5 'end the 56bp repeating unit of the same, the 3' end of the presence of the same the 8bp repeating unit, only repeating a different number; left eye genotype at the 5 'end there are three single haplotype, repetitions were 5.7: 7.7; 8.7; at the 3 'end of the two haplotypes, the number of repetitions of 8 and 23, respectively. Right eye genotype at the 5 'end of the three single haplotype, the number of repetitions of 3.7; 7.7; 8.7. In the 3 'end of the two haplotypes, the number of repetitions of 6 and 25, respectively. Of other flounder Fishes compared to identify the the big mouth the Jian control area structure: termination associated sequence (TAS), central conserved sequence (CSB-F, CSB-E, CSB-D), conserved sequence region sequences (CSB -1, CSB-2, CSB-3). Compare 8 Pleuronectiformes fish control region sequences and contains only a single copy of the repeating unit control area base composition, the results show that the difference between the former species was significantly greater than the latter, the variation coefficient is approximately twice that of the latter. The difference between the two is due to the different kinds of repeating units of the base composition, length and copy number. The establishment of the two systems, tree, one is based on the partial sequence of the control region, BI and ML analysis, 12 species of fish Pleuronectiformes system analysis, if scad Perciformes A as an outgroup. The results show that: the original Pleuronectiformes internal the big mouth Jian taxonomic status; flounder suborder first and sole suborder poly after together and Jian suborder poly, which is consistent with the morphological characteristics. The second is based on the mtDNA genome (control area), BI and ML analysis, building the Pleuronectiformes systems evolutionary tree species selection contains 10 kinds of the Pleuronectiformes fish and other evolutionary relationship with Pleuronectiformes closer 30 species of fish, and Clupeiformes (Far East intends sardines and Pacific herring) as an outgroup. The DAMBE software to calculate the average base content for the A 27.6%; C 29.4%, G 16.8%; T 26.2%, conversion (Ts) / transversion (Tv) = 1.18. The system tree results show that (1) big mouth Qian is exactly the most original location of the Pleuronectiformes system differentiation, and the results of the research of other scholars. Big mouth Jian taxonomic status of the establishment crucial to the for future research Pleuronectiformes system origin. (2) Perciformes divided into three or four groups in the system of classification do not Pleuronectiformes and Carangidae fish only (Perciformes - Ⅰ) form a sister group, and the the Perciformes purpose other taxa relationship far. (3) Although this select few types of Pleuronectiformes still support the Pleuronectiformes is monophyletic origin of the saying, but at the current level.
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