Abstract:In order to study the functions of the HSPs (Heat shock proteins) of Eimeria tenella, we cloned a novel gene (which designated EtHSP) coding HSP of Eimeria tenella by RT-PCR and RACE (Rapid-amplification of cDNA ends). The full-length cDNA sequence of EtHSP was 1802 bp, containing a 1455 bp ORF (Open reading frame) (GenBank Accession No. FJ911605) encoding a deduced protein of 484 amino acids. Real-time PCR revealed that the mRNA level of EtHSP was much higher in sporozoites of E. tenella than other developmental stages (unsporulated oocysts, sporulated oocysts and merozoites). We constructed the recombinant plasmids pET28a(+)-EtHSP , then transformed it into E. coli BL21(DE3) for expression. SDS-PAGE indicated that the fusion protein was expressed in included bodies, with peak expression 6 h after induction by IPTG. Western blotting revealed that the protein was specifically recognized by polyclonal antibodies against E. tenella, showing that the fusion protein was native antigen.

Abstract:Newborn ovary homeobox gene (NOBOX) is an oocyte-specific homeobox gene that plays a critical role in early folliculogenesis and represents a candidate gene for nonsyndromic ovarian failure. We used in silico approach in combination with rapid amplification of cDNA ends (RACE) to clone the full-length cDNA of NOBOX (GenBank Accession No. FJ587509) from porcine oocytes. It contains 1768 bp nucleotides, with an open reading frame (ORF) of 1419 bp. The putative porcine NOBOX gene encodes 472 amino acids with the molecular weight of 51.08 kD and pI of 5.73. Bioinformatics prediction indicates that this protein contains a cd00086 homeodomain. Real-time PCR analysis showed that the NOBOX gene is expressed in various tissues, oocytes and embryos cells (4-cell, 8-cell, morula and blastocyst) at different expression levels. The expression levels of this gene in heart, kidney and oocytes are higher than that in other tissues, which suggested that the NOBOX protein might play an important role in those tissues. The expression of NOBOX in developmental stages is higher than that in GV-stage oocytes, which suggested that the expression of pNOBOX was enhanced in developmental stages.

Abstract:In this study, we evaluated the development potential of caprine mammary gland epithelial cells (CMGECs) after transfection and nuclear transfer into enucleated, ovulated oocytes. We first isolated CMGECs from udders of lactating goats which were transfected with expression plasmid for human lacterrin and selected by G418. Then we chose sixteen neomycin resistant lines and induced them with prolactin for the expression of human lactoferrin checked by Western blotting. The donor cells, expressing human lactoferrin of 75 kD, were fused and activated with enucleated ovulated oocytes. Pronuclear-stage reconstructed embryos were transferred into the oviducts of 16 recipient goats. There were fourteen (87.5%), thirteen (81.3%), and ten (62.5%) pregnancies confirmed pregnant by ultrasound on Day 30, 60, and 90, respectively. Three recipients carried the pregnancies to term and delivered one goat each. Nested PCR-RFLP analysis confirmed that all of the kids were clones of the donor cells. These results demonstrated that CMGECs after transfection remain totipotent for nuclear transfer.

Abstract:To study the effect of exogenous oxygen, we added water solution of paraquat to 7 d cultures of Coriolus versicolor for the next 148 h. Enzyme exudation and biochemiscal process were investigated on the addition of paraquat. We found that compared with the control (without paraquat), the addition of 30 mmol/L paraquat stimulated the activity of manganese dependent peroxidase (MnP), lignin peroxidase(LiP), and laccases (Lac) 7, 2.5 and 1.3 times, respectively. Also, addition of paraquat enhanced activity of superoxide dismutase (SOD) and catalase (CAT) in the first 48 h. Impact of paraquat on ligninolytic enzymes was significant than that on antioxidant enzyme. Addition of paraquat enhanced phenolic compounds and formaldehyde of cultures too. And concentration of malondialdehyde was increased in the first 24 h. The results showed that addition of paraquat promoted oxidative stress, but the antioxidant systems of the fungal strain are sufficient to prevent mycelia from oxidative stress. As exogenous oxygen, paraquat might be a useful substrate in degradation of lignocellulose.

Abstract:Methanotrophs uses methane as the sole carbon and energy source, which cause slow growth, low cell density and hinders its industrial applications. One promising solution is to heterologously express methane monooxygenase (MMO) in other host cells that can be easily cultivated at high cell density. We systematically exploited the possibility of functional expression of pMMO by choosing different promoters and different host cells. The results showed that the recombinants could oxidize methane to methanol. In particular, ethanol could also be detected in the oxidized products, but the enzyme activity was instable, implying that some changes of pMMO expressed in the host cells might have occurred. In addition, SDS-PAGE analysis showed that many recombinants could express the subunits of pMMO, but the enzyme activity could not be detected. In conclusion, correct fold of pMMO in the host cells is important for its functional expression.

Abstract:To express bovine chymosin in yeast, we amplified the prochymosin gene from the plasmid pMD18T-Prochy by PCR, and then cloned the gene into the expression vector pPICZaA, resulting in pPICZaA-Prochy. Pichia pastoris GS115 was used as host cells. Integration of the prochymosin cDNA into the Pichia pastoris genome was confirmed by PCR and sequencing analysis. Chymosin was expressed in Pichia pastoris successfully, and a strong band at about 37 kD was shown by SDS-PAGE. Activity tests showed that the chymosin activity of the culture supernatant was 12.2 SU/mL. This is the first report of successful expression of chymosin in Pichia pastoris. The recombinant Pichia pastoris strain obtained in this study could be further used to produce recombinant chymosin for cheese making.

Abstract:Mammalian zona pellucida 3(ZP3) plays an important role in the induction of capacitating sperm acrosome reaction. In this study, we obtained the soluble mZP3 fusion protein and identified its immunoreactivity. mZP3 cDNA was cloned into plasmid pMAL-p2x, and the recombinant plasmid was transformed into Escherichia coli BL21. To get the soluble mZP3 fusion protein, we tried to optimize the expression conditions, including additives, IPTG concentrations, temperatures and induction duration. Then, Western blotting and ELISA were used to identify the immunoreactivity of the purified protein. Based on the optimization experiments, we concluded that the best soluble expression conditions for the mZP3 fusion protein involved incubation to an A600 of 0.6, addition of glucose to a final concentration of 0.02 mol/L, addition of IPTG to a final concentration of 0.6 mmol/L and then further incubation for 4 h at 25 °C. Western blotting and ELISA showed that the mZP3 fusion protein retained immunoreactivity. The fusion protein can be used as solubility antigens for developing the immunocontraception vaccines of mZP3 and detecting the immune effects of the vaccine.

Abstract:Quorum sensing is an important gene regulatory mechanism in Pseudomonas aeruginosa and controls the expression of numerous virulence factors. We designed and constructed a screening system for quorum-sensing inhibitors. We developed the system by using the lasI and rhlA promoters fused with promoterless sacB as reporters. Using this system we screened a number of Chinese herb extracts, and identified three herb extracts containing inhibitors to the quorum-sensing system and to its regulated genes. The screening system developed was highly efficient and sensitive. It could serve as a useful tool to identify herb compounds that block infections but unlikely render antibiotic resistance in pathogens.

Abstract:In order to characterize the immunogenicity and immunoprotection of the Staphylococcus aureus (S. aureus) surface protein Clumping factor A (ClfA), we amplified clfa genes from S. aureus Newman strain, Wood46 strain and HLJ23-1. The clfa gene from Newman strain was subsequently inserted into pQE-30 vector and the recombinant plasmid was transformed into Escherichia coli strain M15 (pREP4). The recombinant ClfA protein was expressed and purified. Then, we immunized mice with the purified recombinant protein. The antibody level and the concentration of cytokines were measured by enzyme-linked immunosorbent assay. Finally, immunized mice were challenged with S. aureus Newman, Wood46 and HLJ23-1. These results suggested that clfa gene sequences were highly conserved, and the recombinant ClfA was expressed correctly with good antigenicity. The antibody titer and the concentration of cytokines in the immunized groups increased significantly (P<0.05) compared with control, and the mice in the immunized groups were protected against the challenge strains to some extent. These results showed that the ClfA had high immunogenicity and immunoprotective potential.

Abstract:Using recombinant TpNs proteins of Treponema pallidum as antigens, ELISAs are proved to be of higher sensitivity and specificity. However, they can be further increased by using multiple TpNs antigens. According to the epitope analysis, we firstly used linking primers PCRs to obtain an artificial fusion gene segment tpE17-47 containing epitopes of both TpN17 and TpN47. Subsequently, we conducted the prokaryotic expression systems of entire tpN17 and tpN47 genes and tpE17-47 fusion gene. SDS-PAGE analysis and BioRad Gel Image Analysis System showed that the recombinant proteins rTpN17, rTpN47 and rTpE17-47 expressed stably, with 36%, 20% and 28% yields of total bacterial protein, respectively. After purified by Ni-NTA affinity chromatography, all the three recombinant proteins could be recognized by T. pallidum antibody positive sera from syphilis patients. The positive rate of rTpE17-47-ELISA for detecting serum specimens in clinically 630 cases with syphilis was 98.6%. This rate was slightly higher than that by Treponema pallidum particle agglutination (TPPA) (97.9%) (P>0.05), but significantly higher than those by rTpN17-ELISA (83.8%), rTpN47-ELISA (83.3%) and rapid plasma reagin (RPR)(72.1%)(P<0.01). Furthermore, both ELISAs and TPPA for detecting the serum specimens in 25 cases with SLE, 36 cases with RA and 250 healthy cases were all negative. RPR showed positive in 1 case with SLE, 2 cases with RA and 2 healthy cases. This could be a novel serological screening or diagnostic method of syphilis with advantages of quickness, convenience, safety, sensitivity and specificity.

Abstract:To get specific scFv (Single-chain fragment variable) antibody against soluble Ab1-42(Amyloid-beta) oligomers, we constructed a human single-chain Fv (scFv) antibody library by phage display technology. Using RT-PCR, we amplified the variable heavy (VH) and variable light (VL) genes from peripheral blood lymphocytes (PBL). Then we obtained the scFv fragments through SOE-PCR, and the scFv fragments were cloned into the vector pCANTAB5E and electroporated into competent Escherichia coli TG1 cells. Consequently, a scFv phage display library containing 2.5×109 clones was constructed. The recombinant phagemids were rescued by reinfection of helper phage M13K07. Recombinant phages specific for Ab1-42 oligomers were enriched after four rounds of biopanning and the antigen-positive clones were selected from the enriched clones by phage ELISA. Positive clone B19 was used to infect E. coli HB2151 to express soluble scFv antibody. SDS-PAGE and Western blotting analysis showed that the soluble scFv B19 antibody was expressed successfully and could bind specifically to Ab1-42 trimer and protofiber. The specific scFv against Ab1-42 oligomers can be used in the therapeutic research on Alzheimer’s disease.

Abstract:We established xenograft mouse models for studying human lung cancer by using an in vivo imaging system. We first transfected pGL4.17 (luc2/neo) plasmid into human non-small lung cancer A549 cells and screened cell lines stably expressing a luciferase reporter gene with G418. Then we analyzed the correlation of luciferase activity and cells number by in vitro bioluminescence. Furthermore, we compared cell growth characteristics by cell counting. We selected suitable clones and inoculated subcutaneously into nude mice or intravenously into SCID mice to construct lung cancer xenograft models. Using an in vivo imaging system, we monitored the growth and metastasis of the tumors. Finally, we verified the extents of tumorigenesis and metastasis by tissue sections with Hematoxylin and Eosin (HE) staining. In our study, we successfully established the xenograft mouse models for in vivo imaging with luciferase expressed lung cancer cells. These models provided convenient, sensitive, intuitive and stable tools for studying the mechanisms of lung cancer progression and development of anticancer drug.

Abstract:Adiponectin is an adipokine predominantly synthesized and secreted by adipocytes in the white adipose tissue, and it can lower the blood glucose level and increase free fatty acid oxidation. In the current study, we developed the globular domain of adiponectin (gapM1) to treat type II diabetes. In both flask and fermentor, we cultivated Pichia pastoris expressing recombinant gapM1 and established the purification procedure by using gel filtration and anion exchange chromatography. To evaluate the biological activity of recombinant gapM1, we used rat type II diabetes model fed high-fat diet in combination with low-dose STZ (Streptozocin) induction. We purified 200 mg gapM1 with purity of 96% from 10 liters of supernatant. The recombinant gapM1 significantly lowered blood glucose (34.2%), serum triglyceride (79.6%) and total cholesterol (62.1%) in type II diabetes induced rat. Therefore, the recombinant human gapM1 is successfully expressed in Pichia pastoris and effectively treated type II diabetes in rat models.

Abstract:Effects of Rabdocoetsin B (Rabd-B), a diterpenoid extracted from Isodon coetsa, on t(8;21) leukemic cells was tested by CCK-8 assay and Flow cytometry. The A549 cells stably expressing pGC-E1-ZU1-GFP were treated with Rabd-B for 4 h, and the accumulation of GFP was detected by fluorescence microscope. Using Western blotting, we investigated the expression of Casp-3, PARP, S6’, which is a subunit of the 19S regulatory complex of the 26S proteasome, and cellular ubiqutinated proteins. We found that Rabd-B induced growth inhibition and apoptosis of Kasumi-1 cells in a dose-dependent manner. In Kasumi-1 cells treated with 2.5 mmol/L Rabd-B for 24 h, pro-caspase-3 was processed into its active form. The substrate of Casp-3, poly ADP-ribose polymerase (PARP), was cleaved with generation of an 85 kD fragment. The increased GFP fluorescence intensity, cleavage of S6’ and the accumulation of ubiquitinated proteins were found in Kasumi-1 cells treated with Rabd-B. These results suggested that Rabd-B is a potential proteasome inhibitor which induces programmed cell death of t(8;21) cells. Further study might provide evidence for employing Rabd-B in treating human t(8;21) leukemia.

Abstract:In order to improve tensile property of vascular scaffold, we blended silk fibroin with novel human-like collagen with the mass ratio of 9:1, 7:3 and 5:5 (W/W), and then fabricated blood vessel tubular graft by freeze-drying process. We studied microstructure, mechanical properties, elements composites, degradability and biocompatibility of vascular scaffolds. These results showed that tubular scaffold with mass ratio 7:3 exhibited interconnected porous structure with pore size at (60 ± 5) μm and porosity of 85%; achieved the desirable mechanical property (strain of 50% ± 5% and stress of 332 ± 16 kPa); had relatively slow degradation rate; could enhance cell adhesion and proliferation and had superior biocompatibility.

Abstract:The ability to pattern multiple cells through precise surface engineering of cell culture substrates has promoted the development of cellular bioassays, such as differentiation, interaction and molecular signaling pathways. There are several well developed ways to pattern cells. This report describes a method for patterning multiple types of cells based on microfluidics and self-assembled monolayers. We developed two types of micro-dam structures by soft-lithography to locate cells precisely and modified the substrate by a kind of self-assembled monolayer with property of electrochemical desorption to confine cells in specific areas. Finally we could pattern an array of two different types of cells closely and precisely. Cells were confined in specific areas but still shared the same microenvironment, so they could interact through soluble molecules. The substrate was transparent and open, so we could easily apply several instruments for research. With these merits, this cell chip is appropriate for investigating the interaction between different types of cells.

Abstract:To evaluate the absolute quantification of a target gene transcription in engineered lactic acid bacteria, we developed the Real-time RT-PCR based on DNA subtraction. We isolated the total RNA from the bacteria samples by glass bead, and then analyzed the Ct data of real-time RT-PCR by DNA subtraction assay. Using this method, we successfully estimated the expression level of CBHII gene in the strain of genetic engineered Lactococcus lactis. Since this method could avoid the mRNA copy number loss, it could be used to estimate the expression of other genes in lactic acid bacteria.

Abstract:In this study, we efficiently expressed the active antimicrobial peptide (CAD), which fused with the site-mutated coat protein (EDDIE) of the classical swine fever virus, in Escherichia coli. First, we obtained the e-cad fusion gene from the CAD gene and the EDDIE gene using overlapping PCR. Then to get the recombinant expression vector (pETED), the e-cad fusion gene was cloned into the pET30a vector by a site-directed homologous recombination technique. The EDDIE-CAD fusion protein expressed in E. coli as inclusion bodies, and its yield was more than 40% of total bacterial proteins. After renaturated in vitro and self-cleavage of the fusion protein, we obtained the antimicrobial peptide Cecropin AD. Antimicrobial experiments showed that the Cecropin AD efficiently inhibited the growth of G+ and G- bacteria, but it weakly inhibited the growth of Saccharomyces. This method provides an excellent way for high expression of antimicrobial peptides when fused with EDDIE.

Abstract:We established a purification system for glutathione-S-transferase (GST) fusion protein using glutathione coupled magnetic particle. Glutathione was coupled covalently to the surface of magnetic particles with isothiocyanate functional groups. Cell lysate, containing the fusion protein, was then incubated with these glutathione coupled magnetic particles at room temperature. Unbound and non-specifically bound proteins were removed by wash steps. Subsequently, the GST-fusion protein was eluted from the magnetic particles by the addition of reduced glutathione. The resulting fusion protein was tested for purity using SDS-PAGE and demonstrated by Western blotting. The concentration of the fusion protein was measured by Bradford method. Both the conditions for incubation and washing were optimized. The results showed that 150 μg glutathione could be bound on 1 mg of particle surface and 10 mg of the glutatione-coupled magnetic particles was suitable for 100 μL lysate, the optimal incubation time for reaction between particles and lysate was 40 min. The magnetic particles could help purify efficiently GST-fusion protein with a yield of around 516 μg fusion protein per 10 mg particles. Magnetic particles can be successfully used in a simple, rapid and reliable method for the purification of GST-fusion proteins.

Abstract:Yeast Elongation protein 3 (yElp3), the catalytic subunit of the multi-subunit histone acetyltransferase elongator complex, is involved in histone acetylation and transcription, exocytosis and tRNA modification. To study the complex function of yElp3 in yeast, we amplified the yElp3 gene fragment encoding 73aa in the N-terminal from plasmid pYES2-yElp3, and then cloned it into pMXB10 to construct the recombinant plasmid pMXB10-yElp3-219. We expressed the fusion protein in E. coli BL21 (DE3), then purified it by chin affinity column, and finally obtained the soluble purified protein (8.0 kD), which was used to immune the rabbits for acquiring antiserum. ELISA and Western blotting indicated that the polyclonal antibody was of high titration and specificity. Chromatin immunoprecipitation (ChIP) assay with this antibody suggested that yhElp3 exerted the transcriptional regulatory function directly through its presence on the SSA3 gene; this might be the reason that it can rescue the delay activation of SSA3 in elp3? cells.

Abstract:Lysins are murein hydrolases produced by bacteriophage that act on the cell wall of host bacteria to release progeny phages. Research indicated that lysins could kill bacteria effectively and specifically in vitro. To prepare recombinant bacteriophage lysin of Streptococcus (PlyC) and analyze its biological activity, we obtained two genes of PlyC named PlyCA and PlyCB by PCR amplification and inserted them into pET-32a(+), then transformed the recombinant expression vectors pET-32a(+)-PlyCA and pET-32a(+)-PlyCB into E. coli BL21(DE3) respectively. After induction with 0.7 mmol/L IPTG at 30 oC for 7 h, PlyCA and PlyCB were successfully expressed, SDS-PAGE analysis determined that they all constituted above 30% of the total cell proteins. After Ni2+-NTA affinity chromatography, the purity was more than 95%. With the denaturation and protein refolding, we gained the recombinant PlyC. To determine its biological activity, we adopted turbidimetry and plate count method. Before and after lysin treatment, the cell morphology was studied by scanning electron microscopy (SEM). The results showed that the recombinant PlyC could specifically cleavage Streptococcus pyogenes (group A β-hemolytic streptococci). Under the incubation time of 60 min with 4 μg/mL PlyC in Streptococcus pyogenes dilution which OD600 was 0.56, the germicidal effect was up to 99.6%, while SEM observations showed that cell wall cracked and presented cell debris. This finding laid the foundation for the further study and achieving an effective treatment for streptococcal infection.