Comparative transcriptomics gives insights into the evolution of parasitism in Strongyloides nematodes at the genus, subclade and species level

Vicky L Hunt,Akina Hino,Akemi Yoshida,Taisei Kikuchi

doi:10.1038/s41598-018-23514-z

Vicky L Hunt, Akina Hino + Show 2 more

Open Access

https://doi.org/10.1038/s41598-018-23514-z

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Journal: Scientific Reports	Publication Date: Mar 26, 2018
Citations: 26	License type: open-access

Affiliation: University of Miyazaki

Abstract

Strongyloides spp., gastrointestinal nematode parasites of humans and other animals, have genetically identical parasitic and free-living adult life cycle stages. This is an almost unique feature amongst nematodes and comparison of these two stages can provide insights into the genetic basis and evolution of Strongyloides nematode parasitism. Here, we present RNAseq data for S. venezuelensis, a parasite of rodents, and identify genes that are differentially expressed in parasitic and free-living life cycle stages. Comparison of these data with analogous RNAseq data for three other Strongyloides spp., has identified key protein-coding gene families with a putative role in parasitism including WAGO-like Argonautes (at the genus level) and speckle-type POZ-like coding genes (S. venezuelensis-S. papillosus phylogenetic subclade level). Diverse gene families are uniquely upregulated in the parasitic stage of all four Strongyloides species, including a distinct upregulation of genes encoding cytochrome P450 in S. venezuelensis, suggesting some diversification of the molecular tools used in the parasitic life cycle stage among individual species. Together, our results identify key gene families with a putative role in Strongyloides parasitism or features of the parasitic life cycle stage, and deepen our understanding of parasitism evolution among Strongyloides species.

Highlights

Strongyloides nematodes are soil-transmitted gastrointestinal parasites of humans and other animals
Venezuelensis life cycle, respectively (Fig. 1, Supplementary Table S1). We compared these data to the genes that are differentially expressed across the analogous life cycle stages in three other Strongyloides species: S. papillosus (Supplementary Table S2), and analysed RNAseq data we have previously published for S. ratti and S. stercoralis transcriptomes[3]
The proportion of genes differentially expressed between the parasitic female (PF) and free-living female (FLF) stages for all four species ranged between 10–18%, the absolute number of differentially expressed genes were similar for three species – S. venezuelensis, S. stercoralis and S. ratti (2297–2379) and lower for S. papillosus (1761 genes) (Fig. 1A, Supplementary Fig. S1)

Summary

Introduction

Strongyloides nematodes are soil-transmitted gastrointestinal parasites of humans and other animals. The Strongyloides life cycle has genetically identical adult parasitic female (PF) and free-living female (FLF) stages[1], an almost unique feature amongst nematodes. Comparison of S. ratti and S. stercoralis RNAseq data for PF and FLF stages of the life cycle has uncovered key gene families with a putative role in Strongyloides parasitism[3,4]. The four sequenced Strongyloides species can be phylogenetically grouped into two distinct subclades: S. venezuelensis-S. papillosus and S. ratti-S. stercoralis. We have performed RNAseq analysis of S. venezuelensis PF and FLF life cycle stages and compared these data with PF and FLF transcriptomes of three other Strongyloides species, to identify common and unique gene families putatively important in Strongyloides parasitism

Methods

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Conclusion