[Expression and analysis of recombinant pIL-18 in Pichia pastoris].

The porcine IL-18 gene was amplified from recombinant plasmid pGEM-IL-18 by PCR, then the pPIC9K-IL-18 of fusion expression vector was constructed by inserting IL-18 fragment,and was transformed to GS115 by electroporation, multi-copy recombinant strains were screened by G418. The expression of recombinant fusion protein was induced by methanol, SDS-PAGE was used to analyze expression product, fusion protein was purified by Sephadex G-100 column, bioactivity of IL-18 was measured by MTT assays. Experiment results show fusion protein of pIL-18 secreted by GS115,expression reaches the secretion peak of 160 mg/L at 72 h. We have expressed and purified successfully the recombinant pIL-18 with obvious biological activity in Pichia pastoris.

[Molecular relationship of Eurytrema coelmaticum inferred from 18S rRNA sequence].

OBJECTIVE: To elucidate the taxonomic position of Eurytrema coelmaticum by using molecular technology. METHODS: 18S rRNA fragment was amplified from E. coelmaticum genomic DNA by specific conservative primers and sequenced. Homology and phylogenic tree of 18S rRNA sequences between E. coelmaticum and other Dicrocoeliidae trematodes were analyzed and constructed by DNAStar and MEGA3 respectively, and their evolutionary relationship was determined. RESULTS: E. coelmaticum 18S rRNA sequence was with high homology to those from Dicrocoelium dendriticum, Lyperosomum collurionis and Brachylecithum lobatum. Among them, the diversity of E. coelmaticum from D. dendriticum was 2.42%, and that from L. collurionis was 1.75%; D. dendriticum and B. lobatum were closer in evolution only with 1.09% diversity. CONCLUSION: For Dicrocoeliidae trematodes, classification based on 18S rRNA target is valid and the sequences are highly conservative. E. coelmaticum is evolutionarily closer to L. collurionis than to D. dendriticum and B. lobatum.