Abstract
The freshwater snail Oncomelania hupensis is the unique intermediate host of the blood fluke Schistosoma japonicum, which is the major cause of schistosomiasis. The snail inhabits two contrasting environments: the hilly and marshland regions. The hilly snails are smaller in size and have the typical smooth shell, whereas the marshland snails are larger and possess the ribbed shell. To reveal the differences in gene expression between the hilly and marshland snails, a total of six snails, three per environment, were individually examined by RNA sequencing technology. All paired-end reads were assembled into contigs from which 34,760 unigenes were predicted. Based on single nucleotide polymorphisms, principal component analysis and neighbor-joining clustering revealed two distinct clusters of hilly and marshland snails. Analysis of expression changes between environments showed that upregulated genes relating to immunity and development were enriched in hilly snails, while those associated with reproduction were over-represented in marshland snails. Eight differentially expressed genes between the two types of snails were validated by qRT-PCR. Our study identified candidate genes that could be targets for future functional studies, and provided a link between expression profiling and ecological adaptation of the snail that may have implications for schistosomiasis control.
Highlights
The blood fluke Schistosoma japonicum (Platyhelminth: Trematoda) occurs in China and, to a lesser extent, in the Philippines and parts of Indonesia, and human infection by the blood fluke causes a major public health problem especially in lake and marshland regions[1,2]
The 13 genes were concatenated and aligned, and the resulting alignment was used to conduct phylogenetic analysis by the maximum likelihood and Bayesian approaches. Both phylogenetic approaches revealed that all hilly snails or all marshland snails formed a monophyletic group, and that all snails examined in this study were clustered with the subspecies O. hupensis hupensis rather than other subspecies (Supplementary Fig. S1)
Of the remaining 26,176 unigenes that are unannotated, 4,823 harbored a predicted open reading frame (ORF) with a length longer than 150 nucleotides. Through annotating these ORFs with the InterPro protein signature databases, we found 175 unigenes that were assigned to 82 GO terms
Summary
The blood fluke Schistosoma japonicum (Platyhelminth: Trematoda) occurs in China and, to a lesser extent, in the Philippines and parts of Indonesia, and human infection by the blood fluke causes a major public health problem especially in lake and marshland regions[1,2]. Adults of the snail O. hupensis frequently occur in fertile soils with luxuriant growth of weeds[14] Different ecological factors, such as the latitude, humidity, temperature, water level, soil and vegetation, would have critical impacts on the distribution of O. hupensis. The emergence in bottomland for months from February to May permits O. hupensis to lay eggs, and the waterlogging after May is required for their egg-hatching and the development of young snails[16]. As another major ecological factor affecting the development of O. hupensis, vegetation keeps snails warm in winter and supplies shelter from the blazing sunlight in summer, and provides plenty of nutrients during their life cycles[14]. Transcriptome responses to environmental changes in the snail would help understand how they adapt to local environments, which may have important implications for controls against S. japonicum infection
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
