Abstract
BackgroundThe gene regulation mechanism along the life cycle of the genus Schistosoma is complex. Small non-coding RNAs (sncRNAs) are essential post transcriptional gene regulation elements that affect gene expression and mRNA stability. Preliminary studies indicated that sncRNAs in schistosomal parasites are generated through different pathways, which are developmentally regulated. However, the data of sncRNAs of schistosomal parasites are still fragmental and a complete expression profile of sncRNAs during the parasite development requires a deep investigation.Methodology/Principal FindingsWe employed high-throughput genome-wide transcriptome analytic techniques to explore the dynamic expression of microRNAs (miRNAs) and endogenous siRNAs (endo-siRNAs) of Schistosoma japonicum covering the free-living cercarial stage and all stages in the definitive host. This led us to analyze over 70 million clean reads represented both high and low abundance of the small RNA population. Patterns of differential expression of miRNAs and endo-siRNAs were observed. MiRNAs was twice more than endo-siRNAs in cercariae, but gradually decreased along with the development of the parasite. Both small RNA types were presented in equal aboudance in lung-stage schistosomula, while endo-siRNAs accumulated to 6 times more than miRNAs in adult female worms and hepatic eggs. Further, miRNAs were found mainly derived from genes located in the intergenic regions, while endo-siRNAs were mainly generated from transposable elements (TEs). The expression pattern of TE-siRNAs, as well as the pseudogene-derived siRNAs clustered in mRNAs of cytoskeletal proteins, stress proteins, enzymes related to energy metabolism also revealed distinction throughout different developmental stages. Natural antisense transcripts (NATs)-related siRNAs accounted for minor proportion of the endo-siRNAs which were dominantly expressed in cercariae.Conclusions/SignificanceOur results represented a comprehensive expression profile of sncRNAs in various developmental stages of S. japonicum with high accuracy and coverage. The data would facilitate a deep understanding of the parasite biology and potential discovery of novel targets for the design of anti-parasite drugs.
Highlights
Schistosomiasis is a chronic debilitating disease that afflicts more than 200 million individuals in the tropics and sub-tropics regions [1]
Schistosomes could serve as an interesting model to explore gene regulation due to its evolutional position, complex life cycle and sexual dimorphism
We previously indicated that Small non-coding RNAs (sncRNAs) profile in the parasite S. japonicum was developmentally regulated in hepatic and adult stages
Summary
Schistosomiasis is a chronic debilitating disease that afflicts more than 200 million individuals in the tropics and sub-tropics regions [1] The agents of this disease, parasitic flatworms of the genus Schistosoma, have a complex developmental life cycle characterized by a distinct parasitic phase in mammalian and molluscan hosts and a free-living phase in freshwater. There are at least seven discrete developmental stages of the parasite within the definitive (lung-stage schistosomula, juvenile, adult male and female worms, and eggs) and intermediate (sporocysts) hosts as well as the aquatic, free-swimming miracidia and cercariae, with dramatically morphological changes [2] They are among the few platyhelminth parasites to adopt a dioecious lifestyle and possess heteromorphic sex chromosomes, which are arrayed in 7 pairs of autosomal chromosomes and one pair of sexual chromosomes (Z, W), homozygous (ZZ) for male and heterozygous (ZW) for female [3,4]. The data of sncRNAs of schistosomal parasites are still fragmental and a complete expression profile of sncRNAs during the parasite development requires a deep investigation
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