De novo transcriptomic analysis of the female and male adults of the blood fluke Schistosoma turkestanicum

Abstract

Background: Schistosoma turkestanicum is a parasite of considerable veterinary importance as an agent of animal schistosomiasis in many countries, including China. The S. turkestanicum cercariae can also infect humans, causing cercarial dermatitis in many countries and regions of the world. In spite of its significance as a pathogen of animals and humans, there is little transcriptomic and genomic data in the public databases. Methods: Herein, we performed the transcriptome Illumina RNA sequencing (RNA-seq) of adult males and females of S. turkestanicum and de novo transcriptome assembly. Results: Approximately 81.1 (female) and 80.5 (male) million high-quality clean reads were obtained and then 29,526 (female) and 41,346 (male) unigenes were assembled. A total of 34,624 unigenes were produced from S. turkestanicum females and males, with an average length of 878 nucleotides (nt) and N50 of 1480 nt. Of these unigenes, 25,158 (72.7 %) were annotated by blast searches against the NCBI non-redundant protein database. Among these, 21,995 (63.5 %), 22,189 (64.1 %) and 13,754 (39.7 %) of the unigenes had significant similarity in the NCBI non-redundant protein (NR), non-redundant nucleotide (NT) and Swiss-Prot databases, respectively. In addition, 3150 unigenes were identified to be expressed specifically in females and 1014 unigenes were identified to be expressed specifically in males. Interestingly, several pathways associated with gonadal development and sex maintenance were found, including the Wnt signaling pathway (103; 2 %) and progesterone-mediated oocyte maturation (77; 1.5 %). Conclusions: The present study characterized and compared the transcriptomes of adult female and male blood fluke, S. turkestanicum. These results will not only serve as valuable resources for future functional genomics studies to understand the molecular aspects of S. turkestanicum, but also will provide essential information for ongoing whole genome sequencing efforts on this pathogenic blood fluke.