Abstract:The 21st century is regarded as the century of biotechnological drugs, among which monoclonal antibodies and their derived targeting drugs have established themselves as the leading modality of biopharmaceutical pharmaceutics for a wide range of indications covering malignant tumors and autoimmune disorders. Since the manufacturing of the first antibody drug from hybridoma cells, the technologies have been intensely studied and there emerged numerous breakthroughs in recombinant cell line establishment, antibody expression and purification, quality control and other related areas. This article summarizes the critical progresses of antibody drugs expression technologies, especially of mammalian cell expression system, Escherichia coli expression system, the transgenic animal reactor and the cell free protein synthesis system, to give a detailed illustration of the recent advances in antibody drugs development.

Abstract:Monoclonal antibodies have become the main type of antibody drug because of their high specificity and strong affinity to antigen. However, with the intensive study of the natural monoclonal antibody, many defects have faced, such as the limit times of binding to antigen, the unanticipated antibody clearance and antigen accumulation. Therefore, studies are no longer limited to the natural antibody screening, but rather to improve the efficiency of antibody drugs by engineering. In recent years, the bottlenecks in the development of conventional antibody have been solved effectively since the discovery of a novel recycling antibody. Recycling antibody binds to an antigen in plasma and dissociates from the antigen in endosome, thus maximizing the use of antibody and reducing antigen-mediated antibody clearance and antibody-mediated antigen accumulation. In addition, recycling antibodies can enhance the affinity with Fc receptors through further Fc modification. This paper reviews the research progress of circulating antibodies, including its characteristics, transformation methods and prospects.

Abstract:Environmental protection and energy supply are our two major concerns. Greenhouse gases released from energy consumption have serious impact on the environment. CO2 fixation can be used to convert CO2 into fuels or chemicals. However, natural carbon-fixing organisms usually have some disadvantages such as slow growth and low carbon fixation efficiency. Enhancing or remodeling CO2 fixation pathways in model microorganisms can realize CO2 recycling, which can further increase fuel or chemical production and reduce greenhouse gas emission. This review describes in detail metabolic engineering of CO2 fixation pathways to improve chemical production and sugar synthesis, elaborates the role of relevant metabolic pathways and key enzymes in CO2 fixation, introduces the application of electro-biochemical synthesis system, shows the great potential of CO2 fixation, and prospects the future research direction of CO2 fixation.

Abstract:Urease decomposes urea to ammonia, and has application potential in agriculture and medical treatment. Urease proteins include structural proteins (UreA, UreB and UreC) and accessory proteins (UreD/UreH, UreE, UreF and UreG), each of them has its own unique role in urease maturation. The structural proteins form the active center of urease, and the accessory proteins are responsible for the delivery of nickel. We review here the structure and function of bacterial urease complexes, and how each protein interacts to complete the activation process. We hope to provide theoretical basis for the regulation of urease activity and the development of urease inhibitors.

Abstract:The mucosae represent the first line of defense against the invasion of most pathogens, and the mucosal immune system plays a crucial role in the control of infection. Mucosal vaccination can trigger both humoral and cell-mediated immune responses mucosally as well as systemically. Hence, protective immune responses can be elicited effectively by mucosal vaccination. Microfold (M) cells being unique to the mucosal immune system can take up luminal antigens and initiating antigen-specific immune responses. The number of antigen uptake by M cells is directly related to the immune efficacy of mucosal vaccines. Utilizing M cell ligands, M cells-targeting antigen delivery can achieve highly effective mucosal immune responses. The strategy of targeted delivery of antigens to M cells and its applications can be used for the improvement of mucosal immune responses and the development of mucosal vaccines. Despite these efforts, successful development of safe and effective mucosal vaccines remains a big challenge and needs a long way to go, and provably still resort to further researches on cellular properties and functions as well as mucosal immune mechanisms.

Abstract:Pitch deposits have negative effects on product quality, machine performance and production line profitability during pulp and paper manufacture. As traditional pitch control technology cannot provide satisfactory solutions in the pitch deposits, the enzymatic treatment has been rapidly developed for its high efficiency and pollution-free property. In this review, the chemical composition and present form of the pitch in pulp is first introduced, followed by a description of the pitch control enzymes. The emphasis is on the current research on enzymatic solutions to pitch problems, including the reaction mechanism, technology, and the present main problems of lipase, sterol esterases, laccase and lipoxygenase. Finally, the technology prospects in this field are proposed.

Abstract:The study aims to use CRISPR/Cas9 introducing foreign gene targeted knock-in into chicken EAV-HP genome. First, specific primers were designed for amplification of EAV-HP left, right homologous arms and enhanced green fluorescent protein (eGFP) expression cassette. PCR products of homologous arms were ligated to both sides of eGFP by overlap extension PCR, resulting in full-length donor DNA fragment designated as LER. Then LER fragments were cloned into pMD19-T to obtain donor vector pMDT-LER. Subsequently, the donor vector pMDT-LER was transfected into HEK293T cells to verify the expression of eGFP gene. Furthermore, co-transfection of CRISPR/Cas9 expression vector and pMDT-LER into chicken DF-1 cells was performed to achieve eGFP transgenic cells. Meanwhile, eGFP expression was observed in cells, and the event of eGFP integration into EAV-HP genome was detectable by amplification of target DNA. Finally, the transgenic DF-1 cells were passaged seven times, and the stable integration and expression of eGFP was checked by PCR and Western blotting. These results demonstrated that eGFP gene was knocked into the EAV-HP genome successfully, which provides a new integration site for research of transgenic chicken.

Abstract:Natural lignocellulosic materials contain cellulose, hemicellulose, and lignin. Cellulose hydrolysis to glucose requires a series of lignocellulases. Recently, the research on the synergistic effect of lignocellulases has become a new research focus. Here, four lignocellulase genes encoding β-glucosidase, endo-1,4-β-glucanase, xylanase and laccase from termite and their endosymbionts were cloned into pETDuet-1 and pRSFDuet-1 and expressed in Escherichia coli. After SDS-PAGE analysis, the corresponding protein bands consistent with the theoretical values were observed and all the proteins showed enzyme activities. We used phosphoric acid swollen cellulose (PASC) as substrate to measure the synergistic effect of crude extracts of co-expressing enzymes and the mixture of single enzyme. The co-expressed enzymes increased the degradation efficiency of PASC by 44% compared with the single enzyme mixture; while the degradation rate increased by 34% and 20%, respectively when using filter paper and corn cob pretreated with phosphoric acid as substrates. The degradation efficiency of the co-expressed enzymes was higher than the total efficiency of the single enzyme mixture.

Abstract:Escherichia coli was metabolically engineered to produce poly(glycolate-co-lactate-co-3-hydroxybutyrate) using glucose and xylose as carbon sources. The combinatorial biosynthetic route was constructed by the overexpression of a series of enzymes including D-tagatose 3-epimerase, L-fuculokinase, L-fuculose-phosphate aldolase, aldehyde dehydrogenase, propionyl-CoA transferase, β-ketothiolase, acetoacetyl-CoA reductase, and polyhydroxyalkanoate synthase. Overexpression of polyhydroxyalkanoate granule associated protein significantly improved biopolymer synthesis, and the recombinant strain reached 3.73 g/L cell dry weight with 38.72% (W/W) biopolymer content. A co-culture engineering strategy was developed to produce biopolymer from a mixture of glucose and xylose, achieving 4.01 g/L cell dry weight containing 21.54% (W/W) biopolymer. The results of this work offer an approach for simultaneously utilizing glucose and xylose and indicate the potential for future biopolymer production from lignocellulosic biomass.

Abstract:DNA methylation is an important type of epigenetic modification in eukaryotes. In order to research genome-wide methylation levels and patterns in foxtail millet (Setaria italica), the Methylation Sensitive Amplified Polymorphism (MSAP) analysis (employing double digestion with EcoR I and Hpa II/Msp I) was established and applied in two foxtail millet cultivars (Chaogu 58 and Yugu 1). The results showed that 32 pairs of MSAP primers were selected from 100 MSAP primers, and 1 615 and 1 482 clearly distinguishable and reproducible bands were amplified from Chaogu 58 and Yugu 1 respectively, including 3?types of methylation patterns. Cytosine methylation levels of CCGG context in Chaogu 58 and Yugu 1 were characterized as 6.93% and 8.77% respectively. Such different genomic DNA methylation levels between two foxtail millet varieties may provide a preliminary reference for the cultivation of this crop from a novel epigenetic viewpoint.

Abstract:Creating new germplasms and breeding new cultivars in peanut by radiation mutagenesis and tissue culture were conducted in this study, aiming to develop new breeding method of peanut. Mature seeds from Luhua 11, the most commonly grown peanut cultivar in Northern China, were treated by fast neutron irradiation. Then the embryo leaflets were separated from the irradiated seeds and inoculated on the media, and the regenerated seedlings were obtained through somatic embryogenesis pathway. The regenerated seedlings were grafted, acclimated and then transplanted into field and the selfed pods were harvested from 83 regenerated plants. The progenies were selected by the pedigree method, and 107 mutants were obtained from the progenies of the 83 regenerated plants. Different mutants showed obvious variation in many agronomic traits, including main stem height, branch number, pod shape and size, seed coat color, inner seed coat color, oil content and protein content etc. Yuhua 7, a new peanut variety with low oil content, early maturity and waterlogging tolerance was obtained. The yield of Yuhua 7 was over 14% higher than that of the mutagenic parent Luhua 11, and the oil content of kernels was 47.0%, lower than that of parent Luhua 11 with 52.1% oil content. Yuhua 7 had passed peanut variety regional multi-location trials in Liaoning Province in 2016 and its average yield was 13.8% higher than that of the control variety Baisha 1017. It had also passed national peanut variety registration, and the registration ID is “GPD peanut (2018) 370105”. The results show that irradiation mutagenesis combined with tissue culture is an effective method for creating new germplasm and breeding new varieties of peanut.

Abstract:In previous studies, we found that truncated rotavirus VP4* (aa 26–476) could be expressed in soluble form in Escherichia coli and confer high protection against rotavirus in the mouse mode. In this study, we further improved the immunogenicity of VP4* by polymerization. The purified VP4* was polymerized through incubation at 37 ℃ for 24 h, and then the homogeneity of the particles was analyzed by HPLC, TEM and AUC, while the thermal stability and antigenicity was analyzed by DSC and ELISA, respectively. Finally, the immunogenicity and protective efficacy of the polymers analyzed by a mouse maternal antibody model. The results showed that VP4* aggregated into homogeneous polymers, with high thermostability and neutralizing antibody binding activity. In addition, VP4* polymers (endotoxin <20 EU/dose) stimulated higher neutralizing antibodies and confer higher protection against rotavirus-induced diarrhoea compared with the VP4* trimers when immunized with aluminium adjuvant. In summary, the study in VP4* polymers provides a new strategy for the development of recombinant rotavirus vaccines.

Abstract:To investigate the effect of 27nt-miRNA on the differentiation of mesenchymal stem cells into vascular smooth muscle cells. The highly expression plasmids of 27nt-miRNA and anti-27nt-miRNA, and negative control plasmids were constructed, packaged with lentivirus and transfected into human umbilical cord mesenchymal stem cells (hUCMSCs). Collagen IV was added to induce hUCMSCs differentiation into blood vessel smooth muscle cells (VSMCs). The cell viability was measured by MTT assay. The expression of SMA, SM22α at mRNA and protein levels was determined by RT-PCR, immunocytochemical staining and Western blotting. Compared with the negative control group, the viability of the 27nt-miRNA overexpression group was decreased by 20.48% (P<0.05), and the expression of SMA mRNA and SM22α mRNA and protein was significantly increased (P<0.05); the viability of Anti-27nt-miRNA group was increased 18.07% (P<0.05), and the expression of SMA mRNA and SM22α mRNA and protein was decreased (P<0.05). In summary, 27nt-miRNA promotes mesenchymal stem cells differentiation into vascular smooth muscle cells and inhibits cells viability.

Abstract:The aim of the study was to obtain the secondary metabolites in the stem segment of noni and to establish genetic transformation system. The stem segments (no axillary buds) of noni were used as explants to induce the callus, and then to establish the cell suspension system. The factors affecting callus?induction and cell suspension were studied. The results showed that the optimal culture medium for induction was MS with 1.0 mg/L 6-Benzylaminopurine (6-BA) and 0.1 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D), and the optimum culture medium for suspension was MS with 1.0 mg/L 6-BA and 0.1 mg/L 2,4-D, 3% sucrose and the pH of 5.85, with the initial inoculation amount of 37.5 g/L, and the speed of 110 r/min and 25±2 °C applying darkness culture. The suspension cells grew well and showed the maximum growth rate. The growth curve of the suspension cells from the stem segment of noni was in “S-typed” trend, and it should be transformed to the fresh medium between 12 and 20 d. During the culture, the pH of the culture medium decreased and then slowly increased, and the optimum pH for the suspension cells culture of callus from noni’s stem segments was 4.5–5.0. In this study, the stable cell suspension system of the stem segment of noni was successfully established.

Abstract:We explored the improved method to prepare decellularized kidney scaffold and provide experimental basis for kidney tissue engineering and renal pathology and toxicology in vitro research. We perfused rat kidneys with PBS (group control) and prepared the decellularized kidney scaffolds with sodium dodecyl sulfate (SDS) (group S), Triton X-100 combined with SDS (group TS), and Triton X-100 combined with SDS after repeated freezing and thawing (group FTS) in different flow velocity. Meanwhile we measured their fluid distributions and vascular resistance. We examined the degree of decellularization of acellular scaffolds by HE, DAPI staining and DNA quantification. We examined the retention of main composition and structural integrity of decellularized scaffolds by Masson, PAS and immunohistochemical staining. We also detected the ultrastructure, cytotoxicity and the level of growth factor of the scaffolds by scanning electron microscope, MTT and ELISA, respectively. The results showed that the time of decellularization in group FTS was less than that in group S and TS. The vascular resistance of scaffolds decellularized at 10 mL/min flow velocity was lower. The fluid distribution in groups S, TS and FTS was different from that in control group. No residual cell was detected by HE and DAPI staining. DNA content was less than 50 ng/mg. Masson, PAS and immunohistochemical staining results showed that there was extracellular collagen, polysaccharide, type I collagen, type IV collagen, fibronectin and laminin in the decellularized scaffolds, and the scanning electron microscope result showed the scaffolds had the honeycomb structure. The cytotoxicity level of decellularized scaffolds was between grade 0 to 1. The level of VEGF, EGF, IGF-1 and PDGF-BB in group FTS were significantly higher than those in group S and TS. In concluding, combining freeze-thawing with perfusion can produce more ideal and effective whole organ decellularized scaffold of rat kidney, and make a foundation for the study of kidney tissue engineering and in vitro pathology and toxicology of kidney.

Abstract:This study aimed to obtain a recombinant human-source collagen for industrialization. First, based on the Gly-X-Y sequence of human type I collagen, we optimized the hydrophilic Gly-X-Y collagen peptide, designed the human collagen amino acid sequence and the corresponding nucleotide sequence. Next, the expression vector pPIC9K-COL was constructed via endonuclease digestion technology. We obtained an engineering strain of human-source collagen by electrotransforming Pichia pastoris, and then it was fermented, purified and identified. As a result, the expression level reached 4.5 g/L and the purity was over 95%. After amino acid N-terminal sequencing, molecular weight analysis, amino acid analysis and collagenase degradation test, we confirmed that the obtained collagen was consistent with designed primary structure of human-source collagen. After freeze-drying, we analyzed the collagen by scanning electron microscope and cell cytotoxicity, confirming that the collagen has porous fiber reticular structure and superior cytocompatibility. This indicates that human-source collagen has potential to be applied as biomedical material. In conclusion, we successfully obtained the expected human-source collagen and laid a foundation to its further application.

Abstract:Nowadays, available phosphorus (P) deficiency in soil and weed resistance to herbicides have emerged as two severe limiting factors for sustainable agriculture. Therefore, it is of urgent needs to improve plant absorption/utilization ability of the soil P, seek phosphate (Pi)-alternative P fertilizers, and develop new forms of weed control systems. Phosphite (Phi), as a P resource of relatively high amount only less than Pi in Earth, can be converted to utilizable Pi uniquely in some bacterial species by oxidization via its specific dehydrogenase (PTDH), but inhibits plant growth and development. This implies that Phi might rather become a suitable P fertilizer for plants if introducing a PTDH detoxifier from bacteria. Herein, we created the transgenic tobaccos harboring a Pseudomonas PTDH gene (PsPtx) amplified from the soil metagenome previously. RT-PCR showed that the exotic PsPtx gene could express similarly in root, stem and leaf tissues of all transgenic lines. PsPtx transgenic tobaccos could utilize Phi by oxidization as the sole Pi supply, and also outperformed wild-type tobacco with a remarkably dominant growth under Phi stress conditions. Moreover, the PsPtx gene was preliminarily evaluated with a notable quality as a potential candidate of the selection marker in plant genetic transformation. Conclusively, PsPtx and its encoded phosphite dehydrogenase might be applicable for developing a dual system of plant phosphorus utilization and weed control using Phi as P fertilizer and herbicide, and provide an effectual solution to some obstacles in the current crop transgenic studies.