Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Talbot Campus, Poole, BH12 5BB, UK.
Division of Crop Plant Genetics, University of Göttingen, 37075, Göttingen, Germany.
Parasit Vectors. 2020 Feb 17;13(1):81. doi: 10.1186/s13071-020-3926-5.
Sphaerothecum destruens is an obligate intracellular fish parasite which has been identified as a serious threat to freshwater fishes. Taxonomically, S. destruens belongs to the order Dermocystida within the class Ichthyosporea (formerly referred to as Mesomycetozoea), which sits at the animal-fungal boundary. Mitochondrial DNA (mtDNA) sequences can be valuable genetic markers for species detection and are increasingly used in environmental DNA (eDNA) based species detection. Furthermore, mtDNA sequences can be used in epidemiological studies by informing detection, strain identification and geographical spread.
We amplified the entire mitochondrial (mt) genome of S. destruens in two overlapping long fragments using primers designed based on the cox1, cob and nad5 partial sequences. The mt-genome architecture of S. destruens was then compared to close relatives to gain insights into its evolution.
The complete mt-genome of Sphaerothecum destruens is 23,939 bp in length and consists of 47 genes including 21 protein-coding genes, 2 rRNA, 22 tRNA and two unidentified open reading frames. The mitochondrial genome of S. destruens is intronless and compact with a few intergenic regions and includes genes that are often missing from animal and fungal mt-genomes, such as, the four ribosomal proteins (small subunit rps13 and 14; large subunit rpl2 and 16), tatC (twin-arginine translocase component C), and ccmC and ccmF (cytochrome c maturation protein ccmC and heme lyase).
We present the first mt-genome of S. destruens which also represents the first mt-genome for the order Dermocystida. The availability of the mt-genome can assist the detection of S. destruens and closely related parasites in eukaryotic diversity surveys using eDNA and assist epidemiological studies by improving molecular detection and tracking the parasite's spread. Furthermore, as the only representative of the order Dermocystida, its mt-genome can be used in the study of mitochondrial evolution of the unicellular relatives of animals.
球孢虫（Sphaerothecum destruens）是一种专性细胞内鱼类寄生虫，已被确定为淡水鱼类的严重威胁。在分类学上，球孢虫属于 Dermocystida 目，属于 Ichthyosporea 类（以前称为 Mesomycetozoea），位于动物-真菌边界。线粒体 DNA（mtDNA）序列可以作为物种检测的有价值遗传标记，并越来越多地用于基于环境 DNA（eDNA）的物种检测。此外，mtDNA 序列可用于流行病学研究，通过告知检测、菌株鉴定和地理传播。
我们使用基于 cox1、cob 和 nad5 部分序列设计的引物，通过两种重叠的长片段扩增了球孢虫的整个线粒体（mt）基因组。然后将球孢虫的 mt 基因组结构与近亲进行比较，以深入了解其进化。
Sphaerothecum destruens 的完整 mt 基因组长 23939bp，由 47 个基因组成，包括 21 个蛋白编码基因、2 个 rRNA、22 个 tRNA 和两个未识别的开放阅读框。球孢虫的线粒体基因组无内含子且紧凑，少数基因间区包含动物和真菌 mt 基因组中经常缺失的基因，例如四个核糖体蛋白（小亚基 rps13 和 14；大亚基 rpl2 和 16）、tatC（双精氨酸转运酶成分 C）以及 ccmC 和 ccmF（细胞色素 c 成熟蛋白 ccmC 和血红素裂解酶）。
我们展示了球孢虫的第一个 mt 基因组，这也是 Dermocystida 目第一个 mt 基因组。mt 基因组的可用性可以协助使用 eDNA 对真核生物多样性调查中的球孢虫和密切相关的寄生虫进行检测，并通过提高分子检测和跟踪寄生虫传播来协助流行病学研究。此外，作为 Dermocystida 目唯一的代表，其 mt 基因组可用于研究动物单细胞亲缘体的线粒体进化。
