Bullnose射线Myliobatisfreminvillei是一种底栖浮游鹰射线,栖息在墨西哥湾北部和大西洋西部海岸,不连续,来自马萨诸塞州,美国到布宜诺斯艾利斯,阿根廷。Myliobatisfreminvillei目前在2019年IUCN濒危物种红色名录中被列为脆弱物种,因为它经常被手工和商业渔业捕获为副渔获物,沿着阿根廷的海岸,巴西,委内瑞拉。这项研究,第一次,组装并表征了M.fremnvillei的线粒体基因组。M.fremnvillei的富含AT的线粒体基因组长18,356bp,编码22个转移RNA基因(tRNA),2核糖体RNA基因(12S核糖体RNA和16S核糖体RNA),13个蛋白质编码基因(PCGs),并且还包含2,617bp的非编码控制区。在所有13个PCG中都观察到非同义密码子的使用优先于富含AT的密码子。Leu(CTA),Ile(ATC),Phe(TTC),Thr(ACA),Ala(GCC)是最常用的密码子。对所有13个PCG估计的Ka/Ks比率表现出<1的值,表明影响所有这些基因的强纯化选择。与先前声称在Mobulatarapacana的两个线粒体PCG中多样化选择压力的研究结果相反,对相同物种的Ka/Ks值的重新分析表明,在所有13个PCGs中都有纯化选择。在22个tRNA基因中,除tRNA-Ser1具有截短的二氢尿苷臂外,它们都具有苜蓿叶二级结构。在控制区,确定了富含AT的微卫星(n=42)和短串联重复序列(n=6),同一区域的二级结构包含许多发夹环。毛细胞基因组分析支持成虫和成虫科的单系状态。组装的线粒体基因组将有助于弗氏Myliobatisfremnvillei的保护工作。
The Bullnose ray Myliobatis freminvillei is a bentho-pelagic eagle ray that inhabits the north Gulf of Mexico and the Western Atlantic Ocean Coast, discontinuously, from Massachusetts, USA to Buenos Aires, Argentina. Myliobatis freminvillei is currently listed as vulnerable by the 2019 IUCN Red List of Threatened Species given that it is often captured as bycatch by artisanal and commercial fisheries, along the coasts of Argentina, Brazil, and Venezuela. This study, for the first time, assembled and characterized the mitochondrial genome of M. fremnvillei. The A+T rich mitochondrial genome of M. fremnvillei is 18,356 bp long and encodes 22 transfer RNA genes (tRNA), 2 ribosomal RNA genes (12S ribosomal RNA and 16S ribosomal RNA), 13 protein coding genes (PCGs), and also contains a non coding control region of 2,617 bp. Nonsynonomous codon usage with a preference for A+T rich codons was observed in all 13 PCGs. Leu (CTA), Ile (ATC), Phe (TTC), Thr (ACA), and Ala (GCC) were the most frequently used codons. Ka/Ks ratios estimated for all 13 PCGs exhibited values < 1, indicating strong purifying selection affecting all these genes. In contrast to the results of a previous study that claimed diversifying selective pressure in two mitochondrial PCGs of Mobula tarapacana, reanalysis of the Ka/Ks values for the same species indicated purifying selection in all 13 PCGs. Of the 22 tRNA genes, all have a cloverleaf secondary structure except tRNA-Ser1 which has a truncated dihydrouridine arm. In the control region, A+T rich microsatellites (n = 42) and short tandem repeats (n = 6) were identified, and the secondary structure of the same region contained numerous hairpin loops. Phylomitogenomic analyses supported the monophyletic status of the order Myliobatiformes and family Myliobatidae. The assembled mitochondrial genome will assist with conservation efforts in Myliobatis fremnvillei.