IntroductionThe large-scale mullet, Parachelon grandisquamis (Teleostei: Mugilidae), is a monotypic species endemic to the eastern Atlantic Ocean, playing a crucial role in tropical ecosystems. Despite its ecological significance, the systematic classification of Mugilidae remains unresolved, largely due to their diverse morphology, which necessitates the integration of molecular data.MethodsThis study aimed to achieve a comprehensive molecular characterization of the species and establish its matrilineal taxonomic placement using complete mitogenome data. Next-generation sequencing was employed to generate the de novo mitogenome of P. grandisquamis, which spans 16,859 bp and includes 13 protein-coding genes (PCGs), 22 transfer RNAs, two ribosomal RNAs, and a non-coding AT-rich control region (CR).ResultsMost PCGs use ATG as the start codon, with the exception of COI, which begins with GTG. Analysis of amino acids abundance revealed high frequencies for leucine, serine, proline, threonine, and alanine with distinctive codon usage. The proportion of nonsynonymous and synonymous substitutions suggests strong purifying selection in most PCGs, except for ND4L, ND5, and ND6. Most transfer RNAs exhibited typical cloverleaf secondary structures, with the exception of tRNA-Ser1 (GCT), which lacks base pairing in the DHU arm. Mitogenome-based phylogenetic analysis using the Bayesian approach revealed that the monotypic P. grandisquamis is closely related to the genera Chelon and Planiliza within Mugilidae. Furthermore, analysis of the CRs with polymorphic nucleotides in conserved blocks provides additional insight into the development of distinct molecular markers for species identification and population structure analysis of mullets.DiscussionOverall, this study provides a comprehensive analysis of the mitogenomic structure and variation of P. grandisquamis and other mullets, confirming its maternal evolutionary relationships and offering valuable insights for advancing SNP-based species discrimination within the Mugilidae lineage.

中文翻译：

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前沿 |线粒体基因组学分析揭示了鲻鱼单型 Parachelon grandisquamis 的系统发育位置和控制区域的独特结构特征


简介大型鲻鱼 Parachelon grandisquamis （Teleostei： Mugilidae） 是东大西洋特有的单型物种，在热带生态系统中起着至关重要的作用。尽管具有生态学意义，但 Mugilidae 的系统分类仍未解决，这主要是由于它们的形态多样化，这需要整合分子数据。方法本研究旨在利用完整的线粒体基因组数据实现该物种的全面分子表征并建立其母系分类位置。采用下一代测序生成大鳞片假单胞菌的从头线裂基因组，其跨度为 16,859 bp，包括 13 个蛋白质编码基因 （PCG）、22 个转移 RNA、两个核糖体 RNA 和一个富含非编码 AT 的对照区 （CR）。结果大多数 PCG 使用 ATG 作为起始密码子，但 COI 除外，它以 GTG 开头。氨基酸丰度分析显示亮氨酸、丝氨酸、脯氨酸、苏氨酸和丙氨酸的频率较高，具有独特的密码子使用。非同义和同义替换的比例表明，除 ND4L、ND5 和 ND6 外，大多数 PCG 都存在很强的纯化选择。大多数转移 RNA 表现出典型的三叶草二级结构，但 tRNA-Ser1 （GCT） 除外，它在 DHU 臂中缺乏碱基配对。使用贝叶斯方法进行的基于线粒体基因组的系统发育分析表明，单型大鳞片 P. grandisquamis 与 Mugilidae 中的 Chelon 属和 Planiliza 属密切相关。此外，对保守块中具有多态性核苷酸的 CR 进行分析为开发用于鲻鱼物种鉴定和种群结构分析的不同分子标记提供了额外的见解。讨论总体而言，本研究对 P. grandisquamis 和其他鲻鱼的有丝分裂结构和变异进行了全面分析，证实了其母系进化关系，并为推进 Mugilidae 谱系中基于 SNP 的物种区分提供了有价值的见解。