Abstract:Sterol 14a-demethylase (CYP51), the most widely distributed member of the P450 superfamily, is the key enzyme in sterol biosynthesis pathway. CYP51 is not only an important model for fundamental P450 structure/function studies, but also an important target protein of cholesterol-lowering agents, antifungal drugs and herbicides. This article reviewed the research advances in CYP51 at various aspects, including sequence characteristics, physiological roles, catalytic properties in vitro, protein structure, structure-function relationships and inhibition of CYP51. The problems remained in current research and designations of CYP51 inhibitors are also discussed.

Abstract:With the rapid development of genetic engineering and metabolic regulation, antisense technology displays its fascination to the world as a mild regulation genetic tool. Compared with other loss-of-function research methods (e.g. gene knockout), antisense technologies have advantages such as low cost, short period, and easy operation. It has been increasingly used in bacterial metabolic regulation as a powerful genetic tool. This review briefly summarized the latest progress and problems in antisense technologies that are recently used in metabolic engineering of bacteria, and compares the advantages and disadvantages of these technologies.

Abstract:Embryonic stem (ES) cells have the unique capacity to proliferate extensively and maintain the potential to differentiate into advanced derivatives of all three primary germ layers. ES cell lines can also be generated from human blastocyst embryos and are considered promising donor sources for cell transplantation therapies for diseases such as juvenile diabetes, Parkinson’s disease, and heart failure. However, as for organ transplants, tissue rejection remains a significant concern for ES cell transplantation. Another concern is the use of human embryos. One possible means to avoid these issues is by reprogramming the nuclei of differentiated cells to ES cell-like, pluripotent cells. This review discusses the potential of these strategies to generate tailor-made pluripotent stem cells and the role of transcription factors in the reprogramming process.

Abstract:The flanking fragments of the whiEa gene cluster was PCR amplified, cloned and used to construct the gene replacement plasmid pHL643. pHL643 was conjugated into Streptomyces avermitilis NRRL8165 followed by screening for double crossover event, yielding three apramycin resistance and thiostrepton sensitive isolates named ZJ1, ZJ2 and ZJ3, which were deficient in biosynthesis of the grey spore pigment. The whiEa gene replacement of these isolates was confirmed by Southern hybridization. Fermentation of the mutant strains in shaking flasks and HPLC analyses showed that the production of avermectins increased by 47% compared with that of the wild type, indicating that the spore pigment biosynthesis competes with the avermectins biosynthetic pathway.

Abstract:Studies have shown that transgenic plants expressing antiapoptotic genes from baculovirus and animals increase resistance to biotic and abiotic stress. However, the mechanism under these resistances is conjectural, or in some cases even controversy. In the present study, the p35 gene from baculovirus Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) was expressed in tobacco, and for the first time P35 protein was detected in transgenic plants by Western blotting. Inoculation of T1 transgenic tobacco leaves with tobacco mosaic virus (TMV) showed enhanced resistance, and DNA laddering was observed after TMV infection in control but not in transgenic plants. DAB staining showed that TMV infection did not affect peroxide induction of transgenic plants, Western blotting analysis of PR1 protein also showed no difference of control and transgenic plants. Inoculation of fungus (Sclerotinia sclerotiorum) using a detached leaf assay showed enhanced resistance of transgenic leave tissue. RT-PCR analysis demonstrated that p35 gene expression induced earlier expression of PR1 gene after S. sclerotiorum infection. Taken together, our results suggest that the mechanism under enhanced disease resistance by P35 protein is possibly related to the activation of PR-related proteins in addition to the inhibition of programmed cell death, depending on the pathogens challenged.

Abstract:Six recombinant plasmids co-expressing the wild-type GP5 gene or the codon-optimized GP5 gene (containing pan-DR epitope) of porcine reproductive and respiratory syndrome virus (PRRSV) and the E2 gene of classical swine fever virus (CSFV) or the E2 fused with the UL49 of pseudorabies virus (PrV) were constructed based on the suicidal DNA vaccine pSFV1CS-E2 described previously. Expression of GP5 and E2 was confirmed by indirect immunofluorescence assay. The immunogenicity of six plasmids was evaluated in BALB/c mouse model. For the six plasmids, low-level of E2 and GP5 protein specific antibodies could be detected in the sera of the immunized mice. Specific lymphoproliferative responses to the PRRSV or CSFV stimulation were induced in the splenocytes of the immunized mice as demonstrated by CFSE staining assay and WST-8 assay. Antigen specific IFN-g and IL-4 secretion was detected in the splenocytes of some immunized mice by cytokine ELSIA. Fusion with the PrV UL49 in the suicidal vaccines induced significantly higher lymphoproliferative responses and cytokine secretion. Taken together, the suicidal DNA vaccines co-expressing GP5 and E2 could induce PRRSV and CSFV specific humoral and cellular immune responses.

Abstract:A system for the Agrobacterium rhizogenes-mediated transformation and plant regeneration of A. venetum has been developed. The highest transformation frequency was 100%, achieved by using strain LBA9402 with root explants. The highest density of hairy roots reached 22 when root explants transformed by R1000 cultured in the dark. Adventitious shoots were obtained from profusely branched, fast-growing (type PBF) hairy roots, and the adventitious shoot induction frequency was 20%. Regenerated shoots rooted easily on hormone-free 1/2 MS solid medium in 2 weeks. Approximately 1/3 regenerated plants derived from hairy roots exhibited prolific roots with shortened internodes. Whereas other regenerated plants showed another phenotype: long internodes, strong stems, and fleshy blades. However, all regenerated plants displayed a relatively fast development procedure and stronger than the aseptic seedlings. Polymerase chain reaction (PCR) analyses confirmed the hairy root lines and regenerated plants were induced by A. rhizogenes.

Abstract:In order to carry out the process of the repeated batch L-lactic acid fermentation by self-immobilized Rhizopus oryzae, we investigated the effect of medium compositions on the morphology of Rhizopus oryzae. In submerged culture, fungi can be grown as broths of freely suspended mycelia and pellets or clumps, the pellets can be immobilized by themselves. The optimum medium composition for the first patch of fermentation was: 120 g/L glucose, 3 g/L NH4NO3, 0.14 g/L KH2PO4, 0.16 g/L NaH2PO4 (the concentration ratio of K+ and Na+ was 1:1). After 72 h fermentation, the physical form of Rhizopus oryzae was mostly uniform pellet with the diameter of 1.0–2.0 mm , the concentration of L-lactic acid was 100.8 g/L, and the conversion rate of glucose 84%. During 16 batches of repeated fermentation, the L-lactic acid level was above 60.0 g/L and the glucose conversion rate was 75%. The time of every batch was 24 h.

Abstract:Classical swine fever (CSF), which is caused by classical swine fever virus (CSFV), causes significant losses in pig industry in many countries in Asia and Europe. The E2 glycoprotein of CSFV is the main target for neutralizing antibodies. In this study, a recombinant replication-defective human adenovirus expressing the CSFV E2 gene (rAdV-E2) was generated and evaluated for the immunogenicity in rabbits. The results showed that the rabbits immunized with rAdV-E2 developed high-level CSFV-specific antibodies. The rAdV-E2-immunized rabbits were all free of the regular fever and the viral replication in the spleen upon challenge with C-strain, which were seen in the rabbits immunized with the parent adenovirus of rAdV-E2. This indicates that the recombinant adenovirus can be an attractive candidate vaccine against CSF.

Abstract:A b-amylase gene (amyG) was cloned from a Bacillus megaterium WS06 and expressed in the Escherichia coli. Nucleotide sequence anlysis showed the amyG gene is composed of 1638 bp (545 amino acid residues with a Mr of 60.194 kD). The AmyG shows 94.5% sequence homologies with b-amylase from Bacillus megaterium DSM319 and presents a normal b- amylase primary structure, constituted by three parts: the N-terminal signal sequence, the catalytic domain and the C-terminal starch binding domains. The deduced amino acid sequence revealed that several highly conserved regions of the glycosylhydrolase family 14. The amyG gene was overexpressed using the pET21a vector and Escherichia coli BL21(DE3). The recombinant enzyme was purified 7.4 fold to electrophoretic homogeneity and had a Mr of 57 kD (by SDS-PAGE). The enzyme was optimally active at pH 7.0 and 60oC and showed stability at the temperature below 60oC. This enzyme efficiently hydrolyzed starch to yield maltose from non-reducing chain ends by exo-cleavage mode.

Abstract:The cyp51 primers and two pairs of mutant primers which removed different transmembrane region were designed based on Ustilago maydis cyp51 gene structure analysis. The full cyp51 DNA fragment as well as mutant cyp51 genes were amplified and cloned by using the total DNA from Ustilago maydis as template, then subcloned into different expression vectors. The recombinant expression plasmids were transformed into Escherichia coli BL21 (DE3), BL21 (DE3) pLysS and Rosetta (DE3) respectively. A series of experiments leads to the finding that only pET32-YH-35 could be highly expressed at the optimal condition of 30oC induced with 0.5 mmol/L IPTG. The expressed protein (CYP51) showed biological activity by spectra analysis of the protein binding to 4 standard fungicides and to 14 XF-synthetic fungicide compounds, and only one XF-synthetic fungicide compound (XF-113) was similar to standard fungicides in binding constant. This compound is promising to be a new effective antifungal drug. These results will facilitate the further study on the mechanism of pathogenic fungi CYP51 and pesticide molecules, and will provide a new idea for efficient design and development of new anti-fungal drugs.

Abstract:Both interleukin-1 and IgE are important in the pathogenic mechanism of the allergy asthma. cDNA of interleukin- 1receptor antagonist (IL-1ra) and IgE were cloned and a prokaryotic expression vector IL-1ra-Fce/pBV220 was constructed. The vector was transformed into Escherichia coli i BL21(DE3). The fusion protein was expressed successfully in the form of inclusion body. The recombination protein of IL-1ra-Fce was highly purified by chromatography of gel filtration and ion exchange, which was identifited by Western blotting. The cell assay showed that the activity of IL-1ra-Fce was as high as IL-1ra in vitro after refolding. The pharmacokenetic profile of IL-1ra-Fcε and IL-1ra was analyzed, and the half time of IL-1ra-Fce is 4.78 times than that of IL-1ra.

Abstract:According to the codon bias of Pichia pastoris, the mature insect neurotoxin gene LqhIT2 was synthesized based on its amino acid sequence and was cloned to vector of PET-30a (+) and pPIC9K respectively. The fusion protein expressed in E. coli was induced with IPTG and purified with Ni-NTA His Bind Column. The purified fusion protein was used to immunize BALB/c mice, and antiserum obtained was highly specific with the titer of over 1:128 000. Using the antiserum, high-level expression transformants of P. pastoris were screened by dot blotting. The highest expression of recombinant LqhIT2 was about 9 mg/L in baffled flasks. The fusion protein of LqhIT2 expressed in Escherichia coli was not toxic to locust, but the recombinant LqhIT2 expressed in P. pastoris had insecticidal activity against locust through injection.

Abstract:Through PCR amplification, 1.3 kb of 5￠-proximal promoter (TA, 1.3 kb) of the b-actin gene of white cloud mountain minnow Tanichthys albonubes was obtained. Using Genome Walker, a 1.7 kb 5￠-upstream sequence from the proximal promoter of the b-actin gene was isolated, and a further promoter (3.0 kb in size) was amplified according to the isolated 5￠-proximal and upstream sequences (TLA, 3.0 kb). Both the 1.3 kb and 3.0 kb promoter contain elements that were critical to the transcription activity of other species, including the CCAAT Box (-89~-85), CArG Box (-59~-49), TATA Box (-26~-20). Results of putative transcription binding sites analysis of the promoters by software TRANSFAC 6.0 revealed the presence of E-box, several transcript binding sites NF-Y, SP1 (Stimulating Protein 1), AP1 (Activator Protein 1), and some more transcription binding sites existing in the further promoter. The two promoter sequences were inserted into the expression vector to construct the recombinant expression vector, pTA-DsRed and pTLA-DsRed respectively. The vectors were microinjected into the fertilized eggs of Tanichthys albonubes and higher positive rate was obtained and stronger red fluorescence was observed in pTLA-DsRed transgenic fish. RT-PCR analysis showed that RFP (Red fluorescent protein) mRNA level in pTLA-DsRed transgenic fish was 35.7% higher than that of the pTA-DsRed transgenic fish of 15-days-post-hatched. The present study showed that both the proximal and further promoter sequences have effective transcription activities and the 3.0 kb promoter possesses higher potent activity than that of the 1.3 kb promoter.

Abstract:To compare the regulation effects by different promoters on bovine prolactin gene expression in different cell lines, three recombinant bovine prolactin expression vectors were constructed using different promoters, i.e., CMV promoter, bovine prolactin gene promoter and goat β-casein gene promoter, respectively named pCMV, pPRLP and pP1A3, which were transfected into two cell lines, mouse pituitary tumor cell strain (AtT20) and mouse mammary epithelial cell strain (HC11), respectively. RT-PCR and real-time RT-PCR were used to investigate the expression level of the above three vectors in both cell lines. pCMV vector was effectively expressed in both cell lines, pPRLP vector had a similar expression level to that of pCMV in both cell lines, pP1A3 was expressed in HC11 but not in AtT20. pP1A3 was tissue-specific to mammary gland. pPRLP was able to express with a significant level in pituitary and mammary glands, while its tissue-specific characteristics in other tissues need further investigation.

Abstract:Undifferentiated embryonic stem (ES) cells can be maintained in vitro if cultured in the presence of the cytokine leukaemia inhibitory factor (LIF). ES cells can also differentiate in vitro. A particularly efficient method for inducing ES cell differentiation is to culture ES cells as aggregates in the absence of LIF. Under these conditions they form structures known as embryoid bodies (EBs). However the current protocols for EB formation are still diverse. In order to facilitate further study, we carefully controlled the culture conditions for EB formation, and here we report an efficient protocol by which uniformly differentiated EBs were obtained, monitored by measuring the differentiation of beating cardiomyocytes. Furthermore, by using this protocol we observed in long-term cultured plating EBs (>60 days) there still exist cell colony with pluripotency. This observation raised a potential possibility that ES cells may keep pluripotent in a niche provided by differentiated cells.

Abstract:Sodium/proton exchanger 1 (NHE1) plays an important role in the cardiomyocyte development. To study the effect of NHE1 activity in stem cells differentiation into cardiomyocytes, we treated P19 stem cells with dimethyl sulfoxide (DMSO) to initiate cardiomyocyte differentiation. In separate experiments, P19 cells were incubated with NHE1 specific inhibitor EMD87580 during the DMSO induction. The formed embryoid bodies (EBs) were detected with cell morphology detection, immunohistochemisty staining and RT-PCR analysis of expression of cardio-specific gene markers. Results showed that P19 cells were able to differentiate into cardiomyocytes and form the beating cell clusters. However, when cells treated with NHE1 inhibitor EMD87580, they could still form the EBs and proliferate when cell clusters adhered on the culture plate, but cells were unable to differentiate. This observation indicates that inhibition of NHE1 activity affected P19 stem cells differentiating into cardiomyocytes.

Abstract:An enzyme electrode biosensor was used for the amperometric determination of inosine in its tablets by co-immobilizing nucleoside phosporylase and xanthine oxidase on a hydrogen peroxide electrode. As a fundamental electrode the hydrogen peroxide electrode has an advantage of stability in analysis compared with the O2 electrode. The enzyme electrode showed a linear response to inosine in the range of 1~268 mg/L with a response of 60 seconds under a sample injection volume of 25 mL. Based on the enzyme electrode, inosine solutions were determined with an average recover rate of 100.8% and a relative standard deviation (RSD) of less than 0.14% in 20 assays. The lifetime of the enzyme electrode was relative long and could be used continuously at 25oC for 25 days. These results demonstrated that the enzyme electrode biosensor could be used to determine inosine and its derivatives specifically, rapidly, conveniently and economically.

Abstract:The aims of the study were to prepare polyelectrolyte nanocapsules effected by acid phosphatease (ACP) and to study prolonged-releasing performance of the nanocapsules in vitro. Using the layer by layer (LbL) self-assembly technique, polyelectrolyte-b-glycerophosphoric acid nanocapsules were prepared. The morphologies of the nanocapsules were characterized by transmission electron microscopy (TEM) and biocompatibility was well examined by cell-culture method. The drug adriamycin would be loaded in nanocapsules for concentration gradient, the encapsulation efficiency could be calculated. Nanocapsules were reacted with acid phosphatease standard and HepG2 cells that express the ACP, respectively. The prolonged-releasing of adriamycin was verified and tumor cells apoptosis were measured. TEM images showed that the nanocapsule sizes were between 200~300 nm. The material biocompatibility was good until the concentration of nanacapsule was up to 250 mg/mL. The drug encapsulation efficiency reached 68.12%. The release rate of polyelectrolyte (PAH/PSS-b-glycerophosphoric acid)s nanocapsules was higher than in the control nanocapsules at 48h(38% Vs 15%) after its reaction to the ACP standard(P<0.05). Compared with the control, nanocapsules could significantly inhibit the growth of HepG2 cells that expressed the ACP, and the efficiency of cell apoptosis was 7.59% higher at 24h (13.73 Vs 6.14, P<0.05). Polyelectrolytes (PAH/PSS-b-glycerophosphoric acid) nanocapsules in vitro have response to acid phosphatease by which prolonged-releasing can be affected. This property can be used for treatment of some malignant and benign diseases with elevated acid phosphatease level.

Abstract:ACEI and Xyr1 are two regulators that potentially involve in regulation of cellulases and xylanases formation in Trichoderma reesei, they compete for a binding site in the xyn1 (Xylanase1-encoding) gene promoter. To further investigate the mechanism for the transcriptional regulation of cellulases, DNA-binding domains of both ACEI and Xyr1 in T. Koningii were expressed from E. coli. They both showed bindings to the cbh1 promoter fragment (-304 bp to -18 bp) by electrophoresis mobility shift assays, suggesting ACEI and Xyr1 not only compete for binding to xyn1 promoter but also to cbh1 promoter.

Abstract:Genistein is a high specific and noncompetitive inhibitor of epidermal growth factor receptor tyramine kinase domain (EGFR-TK). In the paper, a molecular docking between genistein and EGFR-TK was studied to explore the mechanism of their interaction and antitumor mechanism of genistein by Autodock 3.05 program. The results indicated that genistein located in the active cavity of EGFR-TK by high affinity (△G=?31.2 kJ/mol), and genistein inhibited EGFR-TK by interfering with forming of Lys721/Glu738 ion pair. The inhibition belonged to noncompetitive interaction, in which hydrophobic force and hydrogen bond played key roles.

Abstract:To make a universal gene targeting vector fitting for most gene and delete positive selection gene after targeting successfully, a vector named pA2T was constructed by inserting one neomycin gene (neo) for positive selection and two same herpes simplex virus thymidine kinase gene HSV-tk1 and HSV-tk2 for negative selection into the vector of pGEM-3Z, and two locus of crossing-over (x) in P1 (LoxP) and two different multiple cloning sites (MCS) were inserted into two flanks of neo separately. There were eight rare cloning sites between neo and HSV-tk1 and five rare cloning sites between neo and HSV-tk2, and neo, HSV-tk1 and HSV-tk2 could be translated respectively in the pA2T. Transfection of the pA2T into goat fetus fibroblast cells with LipofectamineTM 2000 conferred resistance to geneticin (G418) and resistance to ganciclovir (GAC) in the cells, which suggested the positive and negative selectable markers could express in the cells and thus the vector pA2T could be used as a universal gene targeting vector. Transformation of the pA2T into the BM25.8 expressing Cre recombinase conferred neo was deleted in the pA2T, which suggested the LoxP was active. Thus, this vector can be inserted by most gene sequences as homologous sequences and positive selection gene can be deleted after targeting successfully, which is very convenience for the production of transgenic animals using gene targeting method.

Abstract:The yield of S-adenosyl-L-methionine (SAM) on high-cell-density fermentation by saccharomyces cerevisiae is mostly affected by the feeding strategy of pre-L-methionine. The mutant strain SAM0801 that could accumulate more SAM was used in this study. Six high-cell-density fermentation experiments in 5 L fermentor were investigated to get the optimal feeding time and amount of L-methionine. The results showed that when 40 g L-methionine was added in the fermentor after 30 h fermentation, a dry cell weight of 100 g/L was achieved. Under this condition, after 58 h fermentation, both the dry cell weight and the yield of SAM reached the maximum, 168 g/L and 14.48 g/L respectively.

Abstract:For rapid screening, we constructed two levels pools (primary and secondary pools) of the bacterial artificial chromosome (BAC) library of Chinese fine wool merino sheep. The primary pools were based on the individual 384-well microtiter plate and were prepared with a three-dimensional pooling scheme. Three dimension (plate, row and column) pools were made for each. The secondary pools were based on the entire BAC library. We developed a PCR based strategy to identify positive BACs from sheep BAC library. First, we analyzed secondary pools DNAs, according to the result, we analyzed correlative primary pools. It was one-step screening (66 PCR reactions) that we could screen a single positive clone from 74 000 BACs by our method, or three-step screening (less than 100 PCR reactions) could screen more clones. By one-step screening (66 PCR reactions), we screened successfully a positive clone 373D13 with polymorphism marker BF94-1.

Abstract:Mitochondrial cytochrome oxidase III(COIII) of duck was successfully amplified by PCR-mtDNA with duck muscle DNA as the template (GenBank Accession No. DQ655706). Cloning sequence analysis shows that the 784 bp nucleotides of COIII gene were contained. Through homology analysis, we confirmed that the cytochrome oxidase III(COIII) was relatively conservative. The method of PCR-mtDNA can be designed to detect the components of duck origin. And then, the method of PCR can be applied to amplify with the muscle DNA of various animal and feedstuff as the template, repeated verification, the primer ( P3, P4 ) with strong specificity and good stability is screened, which can only amplify the sequence of duck. The special sequence contains 226bp, the amplified product of 226 bp was sequenced and analyzed, it showed 100% homology with duck mtDNA COIII gene, which proved the accuracy of the special primer. The test that used different concentration of DNA with P3 and P4 is the sensitive experiment by PCR. The result showed that the primer has much specialty and rather sensitivity. So it is a way to detect the duck origin in the muscle of various animal and feedstuff.

Abstract:We designed a pair of specific primers and a TaqMan fluorescent probe targeting the toxR gene of Vibrio parahaemolyticus (VP). After optimizing the conditions, the specialty, sensitivity and reproducibility of the detection method were evaluated. Results: (1) the developed real-time PCR assay protocol detected only VP and was not affected by other normal food pathogens such as Staphylococcus aureus, Salmonela, Listeria monocytogenes. (2) the limit of detection was 25 copies of toxR gene in the detected samples, and the sensitivity of pure cultures and simulated food samples was 21cfu/ml and 210cfu /g. (3) the developed protocol of real-time PCR assay had a high reproducibility, and the sample’s variation was 0.9% and 1.3% within the same sample and between tests. (4) the standard curve had a good linearity when the gene quantity was between 2.5×101 and 2.5×106 copies. The developed detection assay targeting the toxR gene can quantitatively detect VP in only 3 hours, and thus is an efficacious method for the detection of Vibrio parahaemolyticus.