State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361000, China.
College of Marine Sciences, South China Agricultural University, Guangzhou 510642, China.
Genes (Basel). 2023 Nov 8;14(11):2052. doi: 10.3390/genes14112052.
The green sawfish (Bleeker, 1851), a species of sawfish in the family Pristidae (Rhinopristiformes), mainly inhabits the Indo-West Pacific region. In this study, the complete mitochondrial genome of the critically endangered green sawfish is first described. The length of the genome is 16,804 bp, with a nucleotide composition of 32.0% A, 24.8% C, 13.1% G, and 30.0% T. It contains 37 genes in the typical gene order of fish. Two start (GTG and ATG) and two stop (TAG and TAA/T-) codons are found in the thirteen protein-coding genes. The 22 tRNA genes range from 67 bp (tRNA-) to 75 bp (tRNA-). The ratio of nonsynonymous substitution (Ka) and synonymous substitution (Ks) indicates that the family Pristidae are suffering a purifying selection. The reconstruction of Bayesian inference and the maximum likelihood phylogenetic tree show the same topological structure, and the family Pristidae is a monophyletic group with strong posterior probability. and form a sister group in the terminal clade. And the divergence time of Rhinopristiformes show that and diverged as two separate species in about Paleogene 31.53 Mya. Complete mitochondrial genomes of all five sawfishes have been published and phylogenetic relationships have been analyzed. The results of our study will provide base molecular information for subsequent research (e.g., distribution, conservation, phylogenetics, etc.) on this endangered group.
绿鳍锯鲨（Bleeker, 1851），锯鲨科（Pristidae）（Rhinopristiformes）中的一种锯鲨，主要栖息于印度洋-西太平洋地区。本研究首次描述了极度濒危的绿鳍锯鲨的完整线粒体基因组。基因组全长 16804bp，碱基组成 A 为 32.0%、C 为 24.8%、G 为 13.1%、T 为 30.0%。基因排列顺序符合鱼类的典型特征，共包含 37 个基因。13 个蛋白编码基因中存在 2 个起始密码子（GTG 和 ATG）和 2 个终止密码子（TAG 和 TAA/T-）。22 个 tRNA 基因长度为 67bp（tRNA-）到 75bp（tRNA-）。非同义替换（Ka）与同义替换（Ks）的比值表明，锯鲨科正受到净化选择。贝叶斯推断和最大似然系统发育树的重建显示出相同的拓扑结构，且锯鲨科是一个单系群，具有较强的后验概率。和 在末端分支形成姐妹群。而 Rhinopristiformes 的分化时间表明，和 在古近纪 31.53 Mya 左右已经分化为两个独立的物种。所有五种锯鲨的完整线粒体基因组都已发表，并进行了系统发育关系分析。本研究结果将为该濒危类群的后续研究（如分布、保护、系统发育等）提供基础分子信息。
