ABSTRACT
Objective To clone and identify the heat shock factors(HSFs)of Schistosoma japonicum and analyze its molec?ular structure and alternative splicing pattern. Methods The New Zealand rabbits were infected with the cercariae of Schistoso?ma japonicum and were killed and dissected 42 days post?infection,and the adult worms of S. japonicum and the livers of the rabbits were harvested. Then,the total RNA was extracted by using Trizol reagent. The Sj?hsf open reading frame(ORF)and the alternative splicing fragments were amplified by RT?PCR from the female,male and egg samples,then cloned and verified by enzyme digestion and sequencing. DNAMAN 8.0,InterPro,Mega 6 combined with the Internet databases were utilized to clarify the gene structure,functional domains,alternative splicing pattern,and the homology and phylogenetic tree of HSFs. Re?sults Sj?hsf ORF and the alternative splicing fragments were amplified from the female,male and egg samples of S. japonicum by RT?PCR. After cloning,the positive recombinant plasmids pBSjHSFf?F,pBSjHSFf?M,pBSjHSFf?E containing Sj?hsf ORF, pBSjHSFs?F,pBSjHSFs?M,pBSjHSFs?E with Sj?hsf alternative splicing fragments were identified by enzyme digestion and se?quencing. Three alternative splicing Sj?hsf isoforms were observed through sequence analysis:Sj?hsf?isoform1(2 050 bp),Sj?hsf ?isoform2(2 086 bp)and Sj?hsf?isoform3(2 111 bp);the GenBank accession numbers were KU954546,KX119143 and KX119144,respectively. All the three isoforms located in the same Contig SJC_S000780 of S. japonicum genome and all ex?pressed at female,male and egg stages,but Sj?hsf?isoform1 with a high?level expression. Sj?HSF?isoform1(671 aa)and Sj?HSF?isoform2(683 aa)had DBD(DNA binding domain),HR?A/B and HR?C domains,while Sj?HSF?isoform3(282 aa)stopped in advance without HR?C domain. Phylogenetic tree analysis of HSFs illustrated that Sj?HSFs belonged to HSF1 family,with a close phylogenetic relationship to Sm?HSFs. Conclusions There are three alternative splicing isoforms of Sj?HSF existing in the female,male and egg stages of S. japonicum,but Sj?HSF?isoform1 expresses in a high?level. This study lays the foundation for further study on molecular mechanisms of Sj?HSFs in regulating the heat shock response system.
ABSTRACT
<p><b>OBJECTIVE</b>To examine the expression profile and immunofluorescence localization of the major egg antigen p40 of Schistosoma japonicum (Sjp40) during granuloma formation in the liver of infected New Zealand white rabbits.</p><p><b>METHODS</b>New Zealand white rabbits were infected with S. japonicum cercariae, and the livers were harvested at 29 and 45 days post-infection (dpi). The total RNA of the liver tissues was extracted for expression profiling of Sjp40 by quantitative reverse transcription-PCR (qRT-PCR) with GAPDH of S. japonicum as the endogenous reference gene. The expression of Sjp40 in the liver were detected by Western blotting using anti-Sjp40 monoclonal antibody (mAb) 9G7 or anti-Toxoplasma gondii tSAG1 mAb Y3A8 (control) as the primary antibody. Paraffin sections of the liver were prepared for observing egg granuloma formation using HE staining and for indirect immunofluorescence assay of Sjp40 location in the trapped eggs and egg granulomas.</p><p><b>RESULTS</b>The level of Sjp40 mRNA in the eggs trapped in rabbit livers was significantly higher at 45 dpi than that at 29 dpi (P<0.05), and Western blotting confirmed the presence of Sjp40 protein in the rabbit livers at both 29 and 45 dpi. Immunofluorescence assay demonstrated localized expression of Sjp40 in the immature eggs in the rabbit liver at 29 dpi, but at 45 dpi fluorescence was detected in clusters of mature eggs containing miracidium and in the surrounding egg granulomas.</p><p><b>CONCLUSIONS</b>The transcriptional levels of Sjp40 significantly increased with the maturation of eggs trapped in the rabbit livers. Sjp40 protein spread from the eggs to the surrounding egg granuloma at 45 dpi when acute liver granulomatous lesions occur, suggesting that Sjp40 plays a key role in egg granulomas formation in the livers of infected New Zealand white rabbits.</p>