Project description:Purpose: To identify the putative high pathogenicity for fungal infection of nematodes of the nematode-trapping fungus Duddingtonia flagrans, RNA-seq was used to examine the transcriptional responses in three stages with the treatment of extraction of Caenorhabditis elegans. Methods:mRNA of three interaction stages (0h, 12h, 48h) were generated by deep sequencing, in triplicate, using Illumina Hiseq platforme,and 125 bp paired-end reads were generated.Then raw reads were firstly processed by in-house perl scripts and clean reads were obtained by removing reads containing adapter,poly-N and low quality reads. Clean reads were aligned to the reference genome using TopHat V2.0.12 (Duddingtonia flagrans genome with the accession number of MDKD00000000).Then HTSeq and DESeq were used to analyse the gene expression level. Results: After sequencing, 81.8% of the genes predicted in genome of Duddingtonia flagrans were expressed (FPKM>1) in the samples free of treatment of extraction of Caenorhabditis elegans (0h). After treatment with nematode extracts for 12 h , 40.7% of predicted genes, including 1,752 up-regulated genes and 2,072 down-regulated genes, were found to be differentially expressed (padj<0.05, DESeq) compared to the genes at 0 h. Similarly, after treatment with nematode extracts for 48 h, 13.8% of predicted genes, including 673 up-regulated genes and 628 down-regulated genes, were found to be differentially expressed compared to the genes at 12 h.
Project description:Mobile small RNAs are an integral component of the arms race between plants and fungal parasites, and several studies suggest microRNAs could similarly operate between parasitic nematodes and their animal hosts. However, whether and how specific sequences are selected for export by parasites is unknown. Here we describe a specific Argonaute protein (exWAGO) that is secreted in extracellular vesicles (EVs) released by the gastrointestinal nematode Heligmosomodies bakeri, at multiple copies per EV. Phylogenetic and gene expression analyses demonstrate exWAGO is highly conserved and abundantly expressed in related parasites, including the human hookworm and proteomic analyses confirm this is the only Argonaute secreted by rodent parasites. In contrast, exWAGO orthologues in species from the free-living genus Caenorhabditis are highly diverged. By sequencing multiple small RNA libraries, we determined that the most abundant small RNAs released from the nematode parasite are not microRNAs but rather secondary small interfering RNAs (siRNAs) that are produced by RNA-dependent RNA Polymerases. We further identify distinct evolutionary properties of the siRNAs resident in free-living or parasitic nematodes versus those exported in EVs by the parasite and show that the latter are specifically associated with exWAGO. Together this work identifies an Argonaute protein as a mediator of RNA export and suggests rhabditomorph nematode parasites may have co-opted a novel nematode-unique pathway to communicate with their hosts.