Objective To clone and express cathepsin B gene of Echinococcus granulosus(EgCatB)and analyze EgCatB protein by using bioinformatics tools and online databases. Methods The total RNA of E. granulosus was extracted and reverse?ly transcribed into cDNA as the template sequence for PCR. The EgCatB gene was cloned by using the In?Fusion PCR cloning method and expressed by a wheat germ cell?free system,and then the recombinant protein was identified by Western blotting. The signal peptide,transmembrane helices and subcellular location of the EgCatB sequence were predicted by the online soft?ware SignalP 4.1,TMHMM sever v. 2.0 and TargetP 1.1 respectively. Subsequently,the homologue sequence and conserved sites were aligned by using BLASTP and GeneDoc software. Finally,the structures and the glycosylation modification site of the EgCatB encoding protein were analyzed and predicted in turn by ProtParam,SMART,Predictprotein,Swiss?model,NetOGlyc 4.0 and NetNGlyc 1.0 approaches. Results The EgCatB gene was successfully amplified from cDNA of E. granulosus and ex?pressed in the soluble fractions. The molecular weight of the expressed protein was estimated 35 kDa. The bioinformatics analysis revealed that EgCatB was a classical secreted protein containing a Pept_C1 domain. The homology analysis indicated that the amino acid sequence of EgCatB was highly conserved in the active enzyme sites. The protein structure prediction showed a cata?lytic active center was formed through Gln106,Cys112,His282 and Asn302. It was found that there were nine O?glycosylation sites in the EgCatB sequence,but no N?glycosylation sites. Conclusions The EgCatB gene is cloned and expressed successfully,and the recombinant protein is analyzed by bioinformatics approaches and structure predication. The study provides useful informa? tion for further functional study of the EgCatB protein.

Objective To identify new microsatellite loci from genome sequence database for the study of poly-morphicsm of Schistosoma japonicum. Methods Schistosoma japonicum isolates were obtained from seven endemic sites in China: Tongling and Guichi counties of Anhui Province, Duchang county of Jiangxi Province, Changde and Yueyang Cities of Hunan Province, Shashi City of Hubei Province, Xichang City of Sichuan Province. In order to study the genetic variance, genomic DNAs of 96 individual adult worms were screened against 17 new Schistosoma japonicum microsatellites and the raw data were analyzed by GenMapper 4.0. Furthermore, the varieties of alleles were inverstigated using GenAlEx 6 and genetic distances within a subpopulation (GenClone) and among populations(UPGMA, MEGA 3.1) were analyzed. Results High levels of polymorphism were found between and within population samples, and significant genetic diversity was observed among the seven subpopulations.Within Jiangxi population, most genetic distances (17 loci) among samples range from 25 to 32, indicating a significant genetic diversity. There are three clusters among the seven populations: Jiangxi, Tonglin, Shashi and Changde population, with the genetics distances ranging from 0.017 8 to 0.036 3; Guichi and Yueyang population belong to another cluster, with the genetic distance of 0.024 7; However, Xichang population is an unique group. Its genetic distances to other populations are notable with a range from 0.019 2 to 0.069 3. Conclusion The 17 new polymorphic microsatellites identified may be used as suitable markers for the study on population genetics of Schistosoma japonicum and the genetic variance of the worms seems to be complicated.