野生穿山甲体内的瑞利绦虫异质线粒体基因组。

Heteroplasmic mitochondrial genomes of a Raillietina tapeworm in wild Pangolin.

机构信息

Guangdong Laboratory for Lingnan Modern Agriculture, Center for Emerging and Zoonotic Diseases, College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China.

Guangzhou Zoo and Guangzhou Wildlife Research Center, Guangzhou, 510070, China.

出版信息

Parasit Vectors. 2022 Jun 13;15(1):204. doi: 10.1186/s13071-022-05301-y.

DOI:10.1186/s13071-022-05301-y

PMID:35698206

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC9195439/

Abstract

BACKGROUND

Raillietina species belong to the family Davaineidae, which parasitizes in a wide variety of mammals and birds, causing stunted growth, lethargy, emaciation, and digestive tract obstruction. However, only a limited number of Raillietina species have been identified in wild animals.

METHODS

We analyzed and annotated the complete mitochondrial (mt) genome of a worm from the intestine of a wild pangolin using Illumina sequencing of whole genomic DNA.

RESULTS

These findings showed the presence of two mtDNA sequences in Raillietina sp., designated as mt1 and mt2, with the lengths of 14,331 bp and 14,341 bp, respectively. Both the mts genomes of Raillietina sp. comprised 36 genes, containing 12 protein-coding genes (PCGs), 2 ribosomal RNAs, and 22 transfer RNAs. Gene arrangements of both mt genomes of Raillietina sp. were similar to those of most flatworms, except for taeniids, which shift positions between tRNAL1 and tRNAS2 genes. Twenty of 22 tRNA secondary structures of Raillietina sp. had a typical cloverleaf structure similar to Raillietina tetragona. Sequence differences between the mt1 and mt2 genomes were 4.4%, and this difference arises from the mtDNA heteroplasmic mutations. Moreover, heteroplasmic mtDNA mutations were detected in PCGs, tRNAs, rRNAs, NCRs, and intergenes, but the highest proportion of heteroplasmy of 79.0% was detected in PCGs, indicating the occurrence of mtDNA heteroplasmy in Raillietina sp. To our knowledge, this is the first report of mtDNA heteroplasmy in tapeworm parasites. Phylogenetic analyses of 18S rRNA, ITS2, and 12 PCG sequences demonstrated that the worm was clustered with other Raillietina species in the Davaneidae family.

CONCLUSIONS

We found a novel Raillietina species in wild pangolin with the existence of mitochondrial DNA heteroplasmy. Thus, these findings provide insights into the heterogeneity of the mt genome in parasitic cestodes, and mt genome data contributes to the understanding of pangolin-parasitic cestodes in terms of their molecular biology, epidemiology, diagnosis, and taxonomy.

摘要

背景

雷利绦虫属属于戴文科，寄生在多种哺乳动物和鸟类中，导致生长迟缓、昏睡、消瘦和消化道阻塞。然而，在野生动物中只鉴定出有限数量的雷利绦虫属物种。

方法

我们使用 Illumina 对整个基因组 DNA 进行测序，分析和注释了从野生穿山甲肠道中取出的蠕虫的完整线粒体（mt）基因组。

结果

这些发现表明，雷利绦虫属中有两种 mtDNA 序列，分别命名为 mt1 和 mt2，长度分别为 14331bp 和 14341bp。雷利绦虫属的 mt 基因组均包含 36 个基因，包括 12 个蛋白编码基因（PCGs）、2 个核糖体 RNA 和 22 个转移 RNA。雷利绦虫属的 mt 基因组基因排列与大多数扁形动物相似，除了带绦虫科，它在 tRNAL1 和 tRNAS2 基因之间转移位置。雷利绦虫属的 22 个 tRNA 二级结构中有 20 个具有典型的三叶形结构，类似于雷利绦虫 tetragona。mt1 和 mt2 基因组之间的序列差异为 4.4%，这种差异源于 mtDNA 异质突变。此外，在 PCGs、tRNA、rRNA、NCR 和基因间区检测到异质 mtDNA 突变，但异质率最高的为 79.0%，发生在 PCGs 中，表明雷利绦虫属存在 mtDNA 异质。据我们所知，这是首次在绦虫寄生虫中报道 mtDNA 异质。18S rRNA、ITS2 和 12 个 PCG 序列的系统发育分析表明，该蠕虫与戴文科的其他雷利绦虫属物种聚集在一起。