Construction of a High-efficient Expression Vector of Δ^(12) Fatty Acid Desaturase in Peanut and Its Prokaryotical Expression

A full-length sequence coding for △^12 fatty acid desaturase gene from peanut（Arachis hypogaea L.）was cloned into the expression vector, pRSETB, to generate recombinant plasmid pRSET/HO-A, which was subsequently transformed into expression Escherichia. coli BL21（DE3）pLysS. The △^12 fatty acid desaturase was highly expressed in E. coli BL21（DE3）pLysS in the presence of isopropyl-D-thiogalactopyranoside （IPTG）. The fusion protein was purified and used to form a reaction system in vitro by adding oleic acid as substrate and incubating it at 20℃ for 6 h. Total fatty acids was extracted and methlesterified and then analyzed with gas chromatography. A novel peak corresponding to linoleic acid methyl ester standards was detected with the same retention time. GC-MS （gas chromatogram and gas chromatogram-mass spectrometry） analysis showed that the novel peak was linoleic acid methyl ester. These results exhibited △^12 fatty acid desaturase activity, which could convert oleic acid to linoleic acid specifically.

Generation of Antibodies Against DMRT1 and DMRT4 of Oreochromis aurea and Analysis of Their Expression Profile in Oreochromis aurea Tissues

Sex determination is composed of somatic and germ-line sex differentiation hierarchies whose interaction is poorly understood. A single gene known to control somatic sex determination, the DM-domain containing （Doublesex/Mab-3 DNA-binding motif） gene, is highly conserved across species. Vertebrate DMRT1 （DM-related transcription factor 1） expression occurs predominantly in the testis. Here, however, isolated two distinct DM-domain cDNA from Oreochromis aurea ovary and testis have been named DMRT4 （DM-related transcription factor 4） and DMRT1 by BLAST, respectively. Despite high homology in the DM-domain there is little similarity outside the DM-domain.To better understand the structure, function, and possible roles of DMRT4 and DMRT1 as potential candidates for sex differentiation and sex determination, the intact regions encoding DMRT4 and DMRT1 obtained by PCR were sub-cloned into the vector pMAL-c2x and introduced into the Escherichia coli TB1 cell for efficient fusion expression. After purification and cleavage, DMRT4 and DMRT1 proteins were used to immunize adult rabbits following standard protocols. Consequently, it was found by using Western blot analysis that polyclonal antibodies against DMRT4 and DMRT1 had high specificity. The relative expression levels of DMRT4 and DMRT1 mRNA were determined by fluorescent Real-time RT-PCR in female and male Oreochromis aurea with 13-actin as the internal standard. DMRT1 was expressed only in testis, whereas DMRT4 was over expressed in the ovary, but in both female and male, a slight expression in the brain was also detected. Statistical analysis showed that in the brain, mean DMRT4 mRNA levels in female were significantly higher than in male. Meanwhile, the expression of DMRT4 and DMRT1 protein was also analyzed using the purified antibodies through Western blot and immunohistochemistry. It was found that DMRT4 was exclusively expressed in the ovary and DMRT1 in the testis. Study on DMRT4 and DMRT1 expression facilitated the elucidation of their roles and the understanding of sex differentiation of fish.

Characterization of ST13 Protein Expression in Human Colorectal Cancer Tissues

Objective: To characterize the expression of ST13 protein in human tissuesfor investigation of the function of colorectal cancer related gene ST13. Methods: ST13 ORF wascloned and over-expressed in E.coli. The recombinant ST13 protein was purified by affinitychromatography. ST13 monoclonal antibodies were generated and affinity purified with the recombinantprotein. Immunoblot and immunohistochemical staining were employed to analyze ST13 proteinexpression in human tissues. Results: The expression and purification of the recombinant ST13protein were confirmed by SDS-PAGE. The protein yield reached about 2.5 mg/L of induced bacterialculture with a purity of 91.3%. Three strains of hybridoma were obtained with antibody titers from10~4 to 10~5 in ascites fluids and with high specificity for ST13 protein. Immunoblot showed thatthe apparent Mr of ST13 protein in SW480 cells and human tissues estimated by SDS-PAGE mobility wasapproximately 50 000, which was about 10 000 larger than the 41 324 calculated, but theglycosylation of the protein was excluded. Computer modeling revealed the protein to be ahydrophilic molecule. Immunohistochemical staining showed that ST13 protein was evenly distributedin cytoplasm and expressed in colon, stomach, liver, and other epithelial cells. Differences in thestaining intensity of the protein were observed between normal and cancer tissues as well as amongdifferent normal or carcinoma tissues. Conclusion: ST13 protein is a cytoplasmic molecule with anapparent Mr of 50 000. The protein is expressed in colorectal and other epithelial tissues. Theexpression level of the protein is down-regulated in colorectal cancer and varies among differentnormal and/or carcinoma tissues. Comparison of cDNA sequences and protein characteristics indicatesthat ST13 protein and hsp70-interacting protein (Hip) are same proteins, raising the possibilitythat ST13 protein is involved in the development of colorectal cancer through Hsp70 molecularchaperone machinery.

Study on the Knockout and the Soluble Prokaryotic Expression of VP5 Protein Transmembrane Region of IBDV

[Objective] The research aimed to construct the prokaryotic expression vector of VP5 protein of IBDV.The transmembrane region sequence of VP5 protein was knocked out.Moreover,the expression,separation and purification of objective protein were carried out.[Method] PCR technology was used to respectively amplify the extracellular and intracellular fragments of VP5 gene of IBDV.Then,the two fragments were simultaneously linked to pET-28b（＋）,and it was the vector-intracellular fragment-extracellular fragment-vector.The recombinant expression plasmid pET-VP5-FC and the improved pET-VP5-SC of VP5 whose transmembrane region gene fragment was knocked out were constructed.Then,the expression plasmid was transformed into BL21（DE3）.After IPTG induction,the recombinant protein was purified by Ni affinity chromatography and the gel filtration chromatography.[Result] The soluble expressed VP5 of IBDV was obtained.[Conclusion] The research laid the foundation for further studying the structure and function of VP5 protein.

Cloning and Prokaryotic Expression of NS1 Gene of Porcine Parvovirus (PPV) SD1 Strain

[Objective] The research aimed to provide the theoretical basis for establishing a rapid diagnosis method for porcine parvovirus（PPV）. [ Method] One pair of primers were designed according to PPV genome sequences on GenBank website and the sequences of prokaryotic expression vector pET30a （ ＋ ） with multiple cloning sites. The whole sequence of NS1 gene in PPV SD1 strain was amplified by using PCR technology and the positive recombinant plasmid was analyzed by sequencing and homology comparison. The prokaryotic expression recombinant plasmid PET30a/NS1 was constructed to make its induction expression in Escherichia coll. [ Result] The target fragment with the length of 2 208 bp was obtained from PCR amplification. The nucleotide homologies between the cloned NS1 gene and the reported relevant PPV genes were from 97.3 % to 99.4 %, which indicated that NS1 gene had high conservation. But it had a 12-basepair successive deletion near the hydroxyl end. The cloned PPV NS1 gene was successfully expressed in prokaryotic cell, and its expression products existed mostly in inclusion bodies. [ Conclusion] The results of SDS-PAGE detection showed that the molecular weight of PPV NS1 protein was 86 KD.

Molecular Cloning, Sequence Analysis and Prokaryotic Expression of Ovine Activin Receptor Type IIB(ActRIIB) Gene

Objective] This study aimed to clone ovine activin receptor type llB （Ac-tRIIB） gene, construct the prokaryotic expression vector and express the target gene in vitro, thus providing basis for further function verification. [Method] The template cDNA which was reversely transcribed from total RNA of sheep liver tissue, was subjected to polymerase chain reaction （PCR） using specific primers of ActRIIB. The ful-length cDNA of ovine ActRIIB was obtained by pMD18-T cloning and sequencing for bioinformatics analysis. Ovine ActRIIB encoding sequence was subcloned into prokaryotic expression vector pET41a with restriction sites BamHl/Notl, and then transformed into BL21 （DE3）. The induced products by lPTG were analyzed with SDS-PAGE and Western Blot. [Result] The amplified ful-length cDNA of ovine Ac-tRllB gene was 1 564 bp in length （Genbank accession number： JX422071.1） with an open reading frame of 1 539 bp, encoding 512 amino acides. Ovine ActRllB shared the highest homology （99.6%） with bovine ActRllB. ActRllB had highly ho-mologous C-terminal domains and belonged to the TGFβ family. After prokaryotic expression, an approximately 92 kD His-tagged ActRllB recombinant protein was obtained, which was consistent with the excepted result. [Conclusion] Cloning and successful expression of ovine ActRIIB laid solid foundation for further investigation of its biological function.

Cloning and Expression of Conserved Sequences of cry Gene in E.coli Strain Rosetta(DE3)

[Objective] The aim was to clone the conserved sequences of cry gene and express them in Rosetta （DE3）. [Method] Specific primers were designed according to NCBI database information and the conserved sequences of cry gene were amplified by PCR from Bt transgenic cotton. Then recombinant plasmids were constructed and expressed in E. coil strain Rosetta （DE3）. Finally, the effects of different concentrations and inducing time of IPTG on the expression level of protein were investigated. [Result] Two conserved sequences （304 and 853 bp respectively） of cry gene were amplified. The result of SDS-PAGE confirmed that the recombinant plasmids pGEX-4t-I-304 and pGEX-4t-1-853 could express fusion proteins by IPTG induction and the molecular weight of protein products was 39 and 62.4 kDa respectively, which was in accordance with predicted result. The optimal protein ex- pression conditions were confirmed as induction with 0.15 mmol/L IPTG for 7 h. [Conclusion] This study prepared the ground for the further detection of Bt transgenic crops.

Cloning and Expression of Wheat Heat-shock Protein 60 (HSP60) Gene in E.coli

[Objective]The aim was to construct the wheat heat-shock protein 60 （HSP60） gene in prokaryotic expression vector and express HSP60 efficiently in E.coli. [Method]According to the wheat HSP60 gene sequence in GenBank,a pair of primers P1/P2 were designed and synthesized. The wheat HSP60 gene fragment was amplified from the wheat RNA by RT-PCR and inserted into bacterial expression vector of pGEX-4T-1. The construct of pGEX-4T-1-HSP60 was subsequently transformed into E.coli BL21. [Result]The construct of pGEX-4T-1-HSP60 was verified by restriction endonuclease digestion and sequenced. Compared with the sequences of wheat HSP60 genes in GenBank,homology accounted to 100%. Expression of the GST-HSP60 fusion protein was induced with IPTG. Its molecular weight was about 90 kD. The result was identified by electrophoresis of SDS-PAGE. Expression of the protein bands was consistent with the expected size. [Conclusion]The recombinant prokaryotic expression vector in pGEX-4T-1-HSP60 was constructed successfully and expressed stably in E.coli BL21. This will lay the foundation for further study on the functions of the protein and its mechanism.

Construction of Prokaryotic Expression Vectors of EBP1 Gene from Nervilia Fordii (Hance) Schltr.

[Objective] To construct prokaryotic expression vectors encoding gene Erb3binding protein （EBP1）, which plays important roles in regulating plant organ size from Nervilia fordii （Hance） Schltr. [Methods] PCR products of NfEBP1 with particular restriction sites and expression vectors, pET-28 and pET-16b were digested. Ligation, transformation and selection were performed to construct the recombinant plasmids pET-28-NfEBP1 and pET-16-NfEBP1. The recombinant plasmids were transformed into E. coli BL21 using heat -shock transformation. [Results] Recombinant plasmids pET-28-NfEBP1-1188 and pET-16-NfEBP1-1188 were constructed and transformed into expressional host cells, E. coli BL21, and validated by colony PCR, sequencing and double digestion. [Conclusion] Prokaryotic expression vectors of EBP1 gene from N. fordii were successfully constructed, which laid the foundation for characterization of the gene function.

Cloning and Expression Analysis of the High Mobility B Group Genes in Arabidopsis thaliana

[Objective] The aim was to better research the function and action mode of High Mobility Group B （HMGB） proteins in higher plants. [Method] At2G33450,At5G23405 and At5G23420 genes of HMGB protein family in Arabidopsis thaliana were cloned by the use of RT-PCR method,and the expression of these three proteins in E.coli and Arabidopsis thaliana were detected by using SDS-PAGE,Northern blot and subcellular localization methods. [Result] The results showed that the molecular weights of the three proteins were 17.5,17.0 and 27.0 kD respectively,and the expression levels of the proteins in Arabidopsis thaliana were At5G23420At5G23405At2G33450. In addition,all the three proteins were located in nucleus. [Conclusion] The study will provide a basis for the further research on the biological function of HMGB proteins in higher plants.

Cloning and Prokaryotic Expression of P23 Major Surface Protein Gene from Theileria sergenti

[Objective] The aim was to study cloning and prokaryotic expression of P23 major surface protein gene of Theileria sergenti. [Method] A pair of specific primers was designed according to the sequence of P23 major surface protein of T. sergenti (D84447).The P23 gene was amplified by PCR from genomic DNA of T. sergenti and cloned into pMD18-T vector to construct recombinant clonal vector pMD18-P23. Positive clones were identified by PCR screening and restriction digestion. A recombinant expression plasmid pGEX-4T-P23 was constructed by subcloning the cloned P23 gene into the linearized pGEX-4T-1 vector and transformed into E. coli BL21. After introduction by IPTG,the expressed fusion protein was identified by SDS-PAGE and Western-blotting. [Result] The cloned gene has a total length of 507 bp. Sequencing result showed that the nucleotide sequence of the cloned P23 gene shared 99.4% identity with that of P23 published in GenBank (D84447). The expressed fusion protein was 46 ku in molecular mass. Induction opportunity of zhours after culture inoculation was the best,the induction time of 6 h was the best,and induction temperature of 34 ℃ was the best as well,IPTG of 1 mmol/L had little effect on the expression. Western-blotting indicated that recombinant protein was recognized by specific antibody. [Conclusion] This study would lay a foundation for further research on the prevention and diagnose of T. sergenti.

Identif ication of a hypersensitive response core peptide of HrpZ and its role in increasing grape downy mildew resistance

Harpins play a key role in inducing disease resistance in crops,and identifying their core functional regions and establishing a system for their efficient expression would be very valuable.In this study,large amounts of soluble fusion proteins of harpin HrpZ and its subpeptides were obtained via the optimized induction conditions(28℃ with 0.5 mmol·L^(-1) IPTG for 6 h)in Escherichia coli BL21(DE3).Hypersensitive response(HR)assays demonstrated that the C-terminal 66 aa of HrpZ(HrpZ_C_2_2)elicited a strong HR in tobacco(Nicotiana benthamiana)and grape(Flame Seedless)leaves.Additionally,treatment with HrpZ,and particularly HrpZ_C_2_2,significantly reduced the disease incidence and severity index of field vine leaves and those inoculated with downy mildew.The determination of the physiological parameters indicated that HrpZ,and especially HrpZ_C_2_2,improved the photosynthesis-and chlorophyll fluorescence-related parameters,enhanced the activity of defense-related enzymes,including SOD,POD,CAT and PAL,and increased the H_(2)O_(2) level.Collectively,we efficiently expressed a core peptide of HrpZ and elucidated its strong ability to elicit a HR and resistance to downy mildew.This research provides insight into understanding the structure and function of HrpZ and will advance the application of HrpZ_C_2_2 to increase the resistance of grapevine to downy mildew.

Cloning, Analysis and Prokaryotic Expression of DsSP Gene from Dunaliella salina

[Objective] The purpose of this study was to clone a starch phosphorylase gene from Dunaliella salina and to preliminarily analyze its basic properties and protein expression. [Method] RT-PCR and RACE （rapid amplification of cDNA ends） method was used for gene cloning; basic properties of the gene were analyzed using bioinformatics method; prokaryotic expression vector PGS21a-DsSP was constructed and transformed into E. coil BL21; the fusion protein was purified and detected by GST-SefinoseTM Kit and Western Blot, respectively. [Result] A starch phos-phorylase gene （GenBank accession No. KF061044） named DsSP was successfully isolated from D. salina. Basic properties, subcellular localization, secondary structure and tertiary structure of the protein were analyzed and predicted. The fusion protein was found in the supernatant and inclusion bodies. The supernatant protein was successfully purified. Western Blot analysis showed that the fusion protein was successfully expressed in E. coil BL21. [Conclusion] This study laid experimental foun- dation for further clarifying the function and mechanism of DsSP.

Sequence Analysis of Transcription Factor AtWRKY35 and Construction of Prokaryotic Expression Vector

As members of a super gene family, WRKY transcription factors are widely distributed in higher plants. ln this study, bioinformatic analysis of WRKY35, a member of the WRKY gene family, was carried out. Results indicated that tran-scription factor WRKY35 harbors a WRKYGQK core domain and a Cys2His2 or Cys2His/Cys zinc finger in the 5’ end without transmembrane domain. After PCR amplification and restriction digestion, WRKY35 gene fragment was ligated to prokaryotic expression vector PET28. This study provided basis for expression anal-ysis of WRKY35 protein and subsequent functional identification of WRKY35 gene.

Study on the Factors Influencing Prokaryotic Expression of ScMYB Protein

[Objective] This study aimed to find out the factors influencing the prokary- otic expression of ScMYB protein and optimize the expression conditions. [Method] First, the prokaryotic expression plasmid ScMYB：：pEASY-E1 was constructed; and then the effects of various induction conditions on its expression were studied, in- cluding concentration of inductor IPTG, induction time, induction temperature and OD600 of the bacteria solution. [Result] All the induction time, induction temperature, and OD600 except the concentration of IPTG have significant influence on the expres- sion of target protein. [Conclusion] The expression of target protein reaches the high- est level under the conditions of induction temperature 37 ℃, induction time 4 h and OD600 0.6-1.0.

Expression and Purification of E.coli NrfA Protein and Preparation of Polyclonal Antibody against NrfA

[Objective] This study aimed to clone the E. coil NrfA gene and construct the pET-28a （＋）-NrfA prokaryotic expression vector for preparation of polyclonal anti- body against E. coil NrfA. [Method] E. coil NrfA gene was cloned from the E. coli genome DNA by PCR and inserted into the vector pET-28a（＋） to construct prokary- otic expression vector pET-28a （＋）-NrfA. E. coil NrfA protein was expressed by IPTG induction and purified. Polyclonal antibody against NrfA protein was prepared by im- munizing rabbit with routine method. The specificity and titer of polyclonal antibody was confirmed by ELISA and Western Blotting. [Result] The constructed prokaryotic expression vector pET-28a（＋）-NrfA was induced by IPTG, the recombinant NrfA pro- tein could be expressed effectively. The titer of rabbit anti-NrfA polyclonal antibody obtained by immunization and purification was about 1：204 900. Western Blotting anal- ysis indicated that the obtained polyclonal antibody against E. coil NrfA protein had high titer and high specificity. [Conclusion] E. coil NrfA gene was cloned and the prokaryotic expression vector pET-28a （＋）-NrfA was constructed successfully, poly- clonal antibody with high titer and high specificity was prepared, which laid the foun- dation for the study of NrfA in different strains of bacteria.

Cloning of SAMT Gene cDNA from Chimonanthus praecox and Its Expression in Escherichia coli

[Objective] The aim was to study the cDNA cloning of SMAT gene from Chimonanthus praecox and its expression. [Method] A novel cDNA was cloned by PT-PCR using the total RNA as template, and amplified to the desirable size. The RT-PCR products were reclaimed and transformed into E. coli DH 5o together with the PMD18-T vector after ligating by T-A cloning. Identified by colony PCR and EcoRI and Notl digestion, the recombinant plasmid with target gene was screened out and conducted the sequence analysis. [Result] Results of the sequence analysis showed that the ORF fragment of the SAMT cDNA was successfully cloned from Chimonanthus praecox gene, with the length of 1 196 bp and encoding 380 amino acids fragment which shared 99.2% homology to that of previously reported SAMT cDNA from Chimonanthus praecox （ABU88887）. The SAMT cDNA fragment was sub-cloned into the prokaryotic expression vector PGEX1-4T-1, and the obtained re- combinant plasmid was named PGSAMT. After inducting by 0.01mol/L IPTG, the re- sult of the SDS-PAGE analysis showed that the molecular weight of the fusion ex- pression SAMT protein was about 66 kDa, which was close to the predicted fusion protein derived from the 26 kDa GST band and 42.3 kDa SAMT gene of Chimo- nanthus praecox encoded protein. [Conclusion] This study successfully cloned and expressed the SAMT gene of Chimonanthus praecox.

Fusion Expression of Raphanus sativus-Antifungal Protein 1 (Rs-AFP1) in Escherichia coli and Its Antifungal Activity on Verticillium dahliae

The Raphanus sativus L. antifungal protein 1 (Rs_AFP1) gene was isolated by polymerase chain reaction (PCR). The complete open reading frame and the fragment encoding the putative mature protein were inserted into the prokaryotic expression vector pET_32b(+), respectively. Subsequent expression showed that the Rs_AFP1 was produced in E. coli as a 27 kD fusion protein only when the N_terminal signal peptide was removed. After treatment with thrombin to remove part of the N_terminal His.tag sequence, the bacterially expressed Rs_AFP1 was used for fungal growth inhibition assay which was conducted on Verticillium dahliae Kleb., a soil_born fungus causing the cotton wilt disease. Results showed that, in the liquid medium, the Rs_AFP1 fusion protein at a concentration of 0.3 g/L clearly inhibited the growth of V. dahliae and the germination of spores. Thus the bacterially expressed fusion protein had the antifungal activity against V. dahliae.

Cloning and Expression of Pun1 Gene Controlling Pungency of Pepper (Capsicum spp.)

[Objective] This study was conducted to investigate cloning and expression of Pun1 gene controlling pungency of pepper. [Method] With Capsicum annuum L as a material, the cDNA sequence of Capunl gene was obtained, with a total length of 1 457 bp, coding 440 amino acids. [Result] Phylogenetic analysis showed that Capunl was closest to Pun1 of C. chinense, with a genetic distance of 0.019 3. Plant expression vector pCAM-Punl-GFP was constructed and transformed into to- bacco, and it was found that the protein coded by fusion gene Punl：：GFP was lo- cated on cell membrane. Prokaryotic expression vectors were constructed, and by SDS-PAGE and Western Blot detection, an induced protein with a molecular weight of 63 ku was obtained. It was found by real-time fluorescence quantitative expres- sion that Pun1 gene was expressed at the highest level 30 d after flowering, de- creased then, and could not be detected substantially 40 and 45 d after flowering. [Conclusion] This study provides information and reference for molecular regulation mechanism of Pun1 gene.

Cloning, Expression and Analysis of pal, a Positive Gene Involved in Capsaicin Biosynthesis in Capsicum chinense Jacq

The cDNA sequence of Capal gene was cloned from Capsicum chinense Jacq by RT-PCR and sequenced. Bioinformatics analysis showed that Capal en- codes a putative polypeptide of 683 amino acids with a calculated molecular mass of 74.2 kD and a theoretical pl of 6.9. Multiple sequence alignments and phyloge- netic tree analyses showed that Capal protein of C. chinense is similar to that of Capsicum annuum var. conoides, with an overall sequence similarity of 96%. The prokaryotic expression vector pET-32a-pal was constructed and induced to express in E. coil BL21. The SDS-PAGE analysis showed that the relative molecular mass of the induced new protein is about 74 kD, which was basically identical with that predicted by DNAMAN software （74.3 kD）, Real-time PCR analysis showed that ex- ogenous jasmonic acid （JA） promoted pal expression. The accumulation of capsaicin in pepper was analyzed by high performance liquid chromatography （HPLC）, and the results indicated that exogenous jasmonic acid （JA） can promote the synthesis of capsaicin. This study will provide valuable experimental basis for the research of transcription regulation and explaining the gene function of pal.