Transient expression in microplasmodia of Physarum polycephalum / 生物工程学报

The plasmodium of Physarum polycephalum is a suitable eukaryotic cell for cell cycle investigation, but there is no compatible transient expression system for the plasmodium. Using the promoter and terminator of ardC actin of Physarum polycephalum substituted the CMV IE and SV40 polyA of plasmid pDsRedl-N1, using cassette PardC-MCS-DsRed1-TardC substituted the cassette PardC-hph-TardC of plasmid pTB38, we constructed plasmids pXM1 and pXM2 for transient expression of red fluorescent protein (RFP) in Physarum polycephalum respectively. After reconstituting the transcription elongation factor homologous gene (pelf1) of Physarum polycephalum into the pXM2, we generated a plasmid pXM2-pelf1. After the plasmid pXM1, pXM2 and pXM2-pelf1 were electroporated into the plasmodium of Physarum polycephalum, we observed optimum RFP and PELF1-RFP expression under fluoroscope and confocal microscope between 24-48 h after electroporation, and found that ELF1-RFP expression was accumulated in nucleus of microplasmodium, the optimum electroporation parameters were 40 V/cm electric field, 1 ampere current, and 70 micros electric shock time. The results suggest that this expression system is qualified for transient expression of specific protein in plasmodium of Physarum polycephalum.

Dual promoters enhance heterologous enzyme production from bacterial phage based recombinant Bacillus subtilis / 生物工程学报

The effect of dual promoters on recombinant protein production from bacterial phage based Bacillus subtilis expression system was investigated. Alpha amylase (from Bacillus amyloliquefaciens) and penicillin acylase (from Bacillus megaterium) were selected as the indicating enzymes. Both the promoterless genes and the promoter-bearing genes were isolated through PCR amplification with properly designed primers, and were inserted into plasmid pSG703 that contains the lacZ-cat expression cartridge. The lysogenic B. subtilis (phi105 MU331) was transformed with the resultant recombinant plasmids, and the heterologous genes were thereby integrated into the chromosommal DNA of B. subtilis via homologous recombination. The transformants were designated as B. subtilis AMY1, B. subtilis AMY2, B. subtilis PA1, and B. subtilis PA2, respectively. In the recombinant B. subtilis strains, the inserted sequences were located down stream of a strong phage promoter that could be activated by thermal induction. In B. subtilis AMY1 and B. subtilis PA1, transcription of the heterologous genes was only initiated by the phage promoter after heat shock, whereas in B. subtilis AMY2 and B. subtilis PA2, transcription of the heterologous genes was initiated by dual promoters, the phage promoter and the native promoter. The application of dual promoters increased the productivity of both enzymes, with 133% enhancement for alpha-amylase production and 113% enhancement for penicillin acylase production.

A Secretive Pichia pastoris Expression Vector for Direct PCR Product Cloning / 中国生物工程杂志

A secretive expression vector of Pichia pastoris system which can be used for the direct cloning of PCR products was constructed,and was verified through the expression of recombinant cellobiohydrolase II in Pichia pastoris.A randomly selected fragment was amplified with properly designed primers by PCR.The XhoI and Eam1105Ⅰ restriction sites were included in the 5'end of the fragment,and the Eam1105Ⅰ and XbaI restriction sites were included in its 3'end.The PCR amplified product was inserted into the P.pastoris expression plasmid pPICZ?A through XhoI and XbaI restriction sites and the resultant plasmid was digested with Eam1105Ⅰ,and lastly the big fragment was recovered,generating the P.pastoris expressive Tvector pPICZ?T.Then the cellobiohydrolase II of T.reesei was successfully expressed in P.pastoris with this expressive Tvector.Such results indicated that the constructed expression Tvector was convenient for PCR product cloning,and was effective for heterologous protein expression in P.pastoris.On the other hand,the application of the expression Tvector avoided the introduction of additional amino acids at the Nterminus of the expressed protein,which generally occurred when normal expression vectors were used in secretive expression system.

Expression of the Trichoderma reesei Endoglucanse IV in Pichia pastoris / 微生物学通报

In this work,the Pichia pastoris expression system was applied to express the T.reesei EGⅣ.The eg4 gene was isolated from rice hull induced T.reesei culture through RT-PCR,and was ligated with the Pichia expression vector pPICZ?A,resulting in the recombinant plasmid pPICZ?A-eg4.The recombinant plasmid pPICZ?A-eg4 was then linearized and transformed into P.pastoris GS115,and the eg4 gene was in frame integrated into the Pichia genome through homologous recombination,resulting the recombinant strain P.pastoris-EGⅣ1.With methanol induction,the recombinant strain P.pastoris-EGⅣ1 expressed and secreated EGⅣ into the culture supernatant with CMC activity of 2.11U/mL.The SDS-PAGE analysis showed that the apparent molecular weight of expressed protein was about 50kD,slightly less than that produced by T.reesei.

Antigenic Localization of Specific Allergen in the Body of Dermatophagoides pteronyssinus by Immunohistochemistry / 中国寄生虫学与寄生虫病杂志

Objective To study the localization of specific allergen of Dermatophagoides pteronyssinus. \ Methods\ Through optical microscope,the specific allergens of D.pteronyssinus were observed in paraffin sections using D.pteronyssinus\|specific IgE antibodies from the patient sera. \ Results and Conclusion \ The digestive system was found occupying large parts of body cavity of D.pteronyssinus by HE staining, while the specific allergens of D.pteronyssinus were mostly occurred in the midgut tissue, gut contents, cuticle and reproductive system in the immunostained sections. The results also showed that many parts of D. pteronyssinus were recognized by the specific IgE antibodies obtained from allergic individuals to D.pteronyssinus, which provided a theoretic base for further study of isolation and purification of the specific allergen.