Studies On The MicroRNAs Related Sexual Maturation In Schistosoma Japonicum

Schistosomiasis is a serious public health problem in Egypt and many other countries in thetropical and subtropical regions of Africa, Asia and South America. Currently, there are accumulatedstudies regarding schistosome biology not only from genomics angle but also from proteomics aspects,these studies also include non-coding small RNAs in schistosomes.The main studies of this dissertation focus on the different expression of microRNAs (miRNAs)in different stages of Schistosoma japonicum and also investigate their possible target genes. The resultsof these studies are expected to help to understanding the mechanism of schistosome development andsexual maturation.Briefly, the dissertation include three sections:1) The expression profiles of miRNAs in differentdevelopment stages of Schistosoma japonicum,2) Evaluation of the expressions of miRNA target genesand four eggshell proteins in Schistosoma japonicum treated with the corresponding miRNA inhibitors,3) Preliminary evaluation of the effect of miR-1989silence on worm and egg burden in the miceinfected with Schistosoma japonicum.In the first part, we employed semi-quantitative RT-PCR and real time PCR techniques to detectthe expression of miRNAs in different development stages of Schistosoma japonicum, includingmale-female pairing, gametes development, and egg production. The results showed that some of thesemiRNAs have differently expressed profiles in different stages and different sex. It was worthy to notethat bantam, miR-1989, and miR-31show high expression in female schistosomes, implying that thesethree miRNAs may be involved in the regulations of schistosome sexual maturation and/or eggproduction.In the second part, based on the results of our immunoprecipitation assay, we indentifed severaltraget genes of bantam and miR-31. To further confirm these miRNA target genes identifed, we usedelectroporation to transfer the miRNA inhibitor into in vitro cultured schistosomes. At72h of posttreatment, the worms were collected and total RNAs were isolated for real time RT-PCR analysis. Theresults indicated the expressions of these miRNA target genes and eggshell proteins were altered tosome exgent in schistosomes treated with the miRNA inhibitors.In the last part, we preliminary evaluated the effect of miR-1989silencing on worm and eggburden in the mice infected with Schistosoma japonicum. In the study above, we demonstrated thatmiR-1989has high expression in adult female schistosomes. This suggests that it is likely to play animportant role in female sexual maturation and egg production. To investigate this hypothesis, the micewere infected with Schistosoma japonicum cerariae and then were injected with miR-1989inhibitor,NC inhibitor, PBS via tail vein. The preliminary results showed that the inhibition of miR-1989has nosignificant effect on worm burden in the mice, but has significant impact on some of eggshell proteinexpressions.