Department of Marine Biology, Pukyong National University, Busan 48513, Republic of Korea.
Marine Integrated Biomedical Technology Center, National Key Research Institutes in Universities, Pukyong National University, Busan 48513, Republic of Korea.
Genes (Basel). 2023 Aug 6;14(8):1591. doi: 10.3390/genes14081591.
The mitogenomic evolution of old-world cichlids is still largely incomplete in Western Africa. In this present study, the complete mitogenome of the Cameroon endemic cichlid, was determined by next-generation sequencing. The mitogenome was 16,557 bp long and encoded with 37 genes (13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and a control region). The mitogenome is AT-biased (52.63%), as exhibited in its congener, (52.76% and 53.04%). The majority of PCGs start with an ATG initiation codon, except COI, which starts with a GTG codon and five PCGs and ends with the TAA termination codon and except seven PCGs with an incomplete termination codon. In mitogenome, most tRNAs showed classical cloverleaf secondary structures, except tRNA-serine with a lack of DHU stem. Comparative analyses of the conserved blocks of two Coptodonini species control regions revealed that the CSB-II block was longer than other blocks and contained highly variable sites. Using 13 concatenated PCGs, the mitogenome-based Bayesian phylogeny easily distinguished all the examined old-world cichlids. Except for Oreochromini and Coptodinini tribe members, the majority of the taxa exhibited monophyletic clustering within their respective lineages. clustered closely with (tribe Heterotilapiini) and had paraphyletic clustering with its congener, . The Oreochromini species also displayed paraphyletic grouping, and the genus showed a close relationship with Coptodinini and Heterotilapiini species. In addition, illustrating the known distribution patterns of old-world cichlids, the present study is congruent with the previous hypothesis and proclaims that prehistoric geological evolution plays a key role in the hydroclimate of the African continent during Mesozoic, which simultaneously disperses and/or colonizes cichlids in different ichthyological provinces and Rift Lake systems in Africa. The present study suggests that further mitogenomes of cichlid species are required, especially from western Africa, to understand their unique evolution and adaptation.
西非地区旧大陆慈鲷的线粒体基因组进化仍然很大程度上尚未完成。在本研究中，通过下一代测序确定了喀麦隆特有慈鲷的完整线粒体基因组。该线粒体基因组长 16557bp，编码 37 个基因（13 个蛋白编码基因、2 个核糖体 RNA 基因、22 个转移 RNA 基因和一个控制区）。与同属物种 一样， （52.76%和 53.04%）表现出 AT 偏倚。大多数 PCGs 以 ATG 起始密码子开始，除了 COI，它以 GTG 密码子开始，五个 PCGs 以 TAA 终止密码子结束，除了七个 PCGs 具有不完整的终止密码子。在 线粒体基因组中，大多数 tRNA 显示出典型的三叶形二级结构，除了 tRNA-丝氨酸缺乏 DHU 茎。对两个 Coptodonini 物种控制区保守区的比较分析表明，CSB-II 区比其他区更长，包含高度可变的位点。使用 13 个串联的 PCGs，基于线粒体基因组的贝叶斯系统发育很容易区分所有检查过的旧大陆慈鲷。除了 Oreochromini 和 Coptodinini 部落成员外，大多数分类群在各自的谱系中表现出单系聚类。 与 （ Heterotilapiini 部落）聚类密切，与其同属物种 表现出并系聚类。Oreochromini 物种也表现出并系分组，属 与 Coptodinini 和 Heterotilapiini 物种关系密切。此外，本研究展示了旧大陆慈鲷的已知分布模式，与之前的假说一致，并宣称中生代非洲大陆的古地质演化在水气候中发挥了关键作用，同时在非洲的不同鱼类区系和裂谷湖系统中分散和/或殖民慈鲷。本研究表明，需要进一步研究慈鲷物种的线粒体基因组，特别是来自西非的，以了解它们独特的进化和适应。
